large coil gun
IamSmooth, Fri Feb 20 2015, 09:20PMIs anyone aware of the largest home-built coil gun on this or another forum? I've seen small ones that shoot small pieces of metal across a room. I'm curious if anyone has built one that can cause serious damage.
(I'm not talking about the Navy's)
Re: large coil gun
DerAlbi, Sat Feb 21 2015, 02:06AM
i am on the way to 100J Projectile energy. but it will take some time.
DerAlbi, Sat Feb 21 2015, 02:06AM
i am on the way to 100J Projectile energy. but it will take some time.
Re: large coil gun
Signification, Sat Feb 21 2015, 02:26AM
Do you have, in mind, a particular projectile mass and efficiency at 100J ?
Signification, Sat Feb 21 2015, 02:26AM
Do you have, in mind, a particular projectile mass and efficiency at 100J ?
Re: large coil gun
DerAlbi, Sat Feb 21 2015, 03:44AM
exit velocity will be 100m/s. but its not the time for details right now.
DerAlbi, Sat Feb 21 2015, 03:44AM
exit velocity will be 100m/s. but its not the time for details right now.
Re: large coil gun
Sulaiman, Sat Feb 21 2015, 09:16AM
The first shot from my first coil gun nearly killed my son,
he almost died laughing at how pathetically weak it was !
Sulaiman, Sat Feb 21 2015, 09:16AM
IamSmooth wrote ...
Is anyone aware of the largest home-built coil gun on this or another forum? I've seen small ones that shoot small pieces of metal across a room. I'm curious if anyone has built one that can cause serious damage.
(I'm not talking about the Navy's)
Is anyone aware of the largest home-built coil gun on this or another forum? I've seen small ones that shoot small pieces of metal across a room. I'm curious if anyone has built one that can cause serious damage.
(I'm not talking about the Navy's)
The first shot from my first coil gun nearly killed my son,
he almost died laughing at how pathetically weak it was !
Re: large coil gun
DerAlbi, Sat Feb 21 2015, 01:31PM
Yeah, true... the easy CG-Designs just suck. Also on Youtube.. if you watch Jason Murray (most successfull coilgunner on youtube i guess), the views are only driven by the appearance.. not technical data or capability.
Shooting at stuff that breaks easily anyway makes a good video.. but anyone with a brain knows how pathetic it actually is.
However he got 25J which is not too bad at all.
DerAlbi, Sat Feb 21 2015, 01:31PM
Yeah, true... the easy CG-Designs just suck. Also on Youtube.. if you watch Jason Murray (most successfull coilgunner on youtube i guess), the views are only driven by the appearance.. not technical data or capability.
Shooting at stuff that breaks easily anyway makes a good video.. but anyone with a brain knows how pathetic it actually is.
However he got 25J which is not too bad at all.
Re: large coil gun
hen918, Sat Feb 21 2015, 02:58PM
I have eight 3300uf, 400v capacitors and intend to make a 1200v 2200uf bank out of 6 of them, but the large size of the bank makes a coilgun somewhat impractical.
hen918, Sat Feb 21 2015, 02:58PM
I have eight 3300uf, 400v capacitors and intend to make a 1200v 2200uf bank out of 6 of them, but the large size of the bank makes a coilgun somewhat impractical.
Re: large coil gun
Signification, Sat Feb 21 2015, 03:48PM
hen918, I would go for it--I don't think 1200v will be problematic--but I assume that is not your worry. I have a batch of electrolytics: 10,000uF 450v (525V surge with heavy duty terminals) and was thinking of doing that three-in-seies type configurations with 1200v to 1450v. Mainly I am curious about coilguns with higher voltage electrolytic banks energizing magnet wire coils. I also have some 6800uF and 6200uF @ 450vdc.
Have you ever known of energy storage caps (or any other than 'lytics) used in coilguns?
Signification, Sat Feb 21 2015, 03:48PM
hen918, I would go for it--I don't think 1200v will be problematic--but I assume that is not your worry. I have a batch of electrolytics: 10,000uF 450v (525V surge with heavy duty terminals) and was thinking of doing that three-in-seies type configurations with 1200v to 1450v. Mainly I am curious about coilguns with higher voltage electrolytic banks energizing magnet wire coils. I also have some 6800uF and 6200uF @ 450vdc.
Have you ever known of energy storage caps (or any other than 'lytics) used in coilguns?
Re: large coil gun
DerAlbi, Sat Feb 21 2015, 03:55PM
May i ask why somwething else would be desireable? You can use big foil caps of course. but why would you...
Caps (electrolytics) are not the limiting factor.
There was one guy here who used nonpolar caps and got highest efficiency figues (20% ?) ever seen in this forum at room temperature. But this was due to a novel design and creativity. He called every SCR-based design as "monkey-design" which raged everyone red hot
. but well... he was just right.
DerAlbi, Sat Feb 21 2015, 03:55PM
May i ask why somwething else would be desireable? You can use big foil caps of course. but why would you...
Caps (electrolytics) are not the limiting factor.
There was one guy here who used nonpolar caps and got highest efficiency figues (20% ?) ever seen in this forum at room temperature. But this was due to a novel design and creativity. He called every SCR-based design as "monkey-design" which raged everyone red hot
. but well... he was just right.Re: large coil gun
dexter, Sat Feb 21 2015, 06:35PM
what did he used?
dexter, Sat Feb 21 2015, 06:35PM
DerAlbi wrote ...
May i ask why somwething else would be desireable? You can use big foil caps of course. but why would you...
Caps (electrolytics) are not the limiting factor.
There was one guy here who used nonpolar caps and got highest efficiency figues (20% ?) ever seen in this forum at room temperature. But this was due to a novel design and creativity. He called every SCR-based design as "monkey-design" which raged everyone red hot . but well... he was just right.
May i ask why somwething else would be desireable? You can use big foil caps of course. but why would you...
Caps (electrolytics) are not the limiting factor.
There was one guy here who used nonpolar caps and got highest efficiency figues (20% ?) ever seen in this forum at room temperature. But this was due to a novel design and creativity. He called every SCR-based design as "monkey-design" which raged everyone red hot
. but well... he was just right.what did he used?
Re: large coil gun
DerAlbi, Sat Feb 21 2015, 09:43PM
..well SCRs still, however without a freewheeling diode,so the caps could repolarize. thus getting energy back from the coil. this left energy is then used to feed the next coil.
He is actually using the full positive sine-wave current, instead of only the quater waveform. this has inherently much much higher efficiency (not wasting half the energy, and having less suckback)
as said: real advancements are only possible by creativity. building the same circuit again and again wont improve things. the limit has been reached.
e.g. Signification has his big Puck-SCR... and big plans in mind - not realizing, that bigger means only deeper into saturation thus less efficiency and at the end: is another crappy design with <5%.
Getting a decent energy out of it will require even more input capacitance.. it will only grow impractical.
Yes this is crying and raging... but my complaints are on topic:
I am complaining right now that most fo the CG-Community is a bunch of kids that found CGs on youtube and want to impress their friends. the minority are advanced hobbyist and even less are educated engineers. the problem is that the advanced hobbyist are really good at explaining things to otheres but most of the explainations are wriong in the fine details.
Thats in no way a basis for "large coil gun"s. Which actually need to be engineered by maths - where every minor error would offset the results.
CGs are a good school project, but most people here who claim to make more out of it wasting only time and money on a concept that simply cant be scaled up.
Or more comprehensive: if you increase your output power you are likely to decrease your technical worthyness. ...and noone gets it
DerAlbi, Sat Feb 21 2015, 09:43PM
..well SCRs still, however without a freewheeling diode,so the caps could repolarize. thus getting energy back from the coil. this left energy is then used to feed the next coil.
He is actually using the full positive sine-wave current, instead of only the quater waveform. this has inherently much much higher efficiency (not wasting half the energy, and having less suckback)
as said: real advancements are only possible by creativity. building the same circuit again and again wont improve things. the limit has been reached.
e.g. Signification has his big Puck-SCR... and big plans in mind - not realizing, that bigger means only deeper into saturation thus less efficiency and at the end: is another crappy design with <5%.
Getting a decent energy out of it will require even more input capacitance.. it will only grow impractical.
Yes this is crying and raging... but my complaints are on topic:
I am complaining right now that most fo the CG-Community is a bunch of kids that found CGs on youtube and want to impress their friends. the minority are advanced hobbyist and even less are educated engineers. the problem is that the advanced hobbyist are really good at explaining things to otheres but most of the explainations are wriong in the fine details.
Thats in no way a basis for "large coil gun"s. Which actually need to be engineered by maths - where every minor error would offset the results.
CGs are a good school project, but most people here who claim to make more out of it wasting only time and money on a concept that simply cant be scaled up.
Or more comprehensive: if you increase your output power you are likely to decrease your technical worthyness. ...and noone gets it
Re: large coil gun
Signification, Sun Feb 22 2015, 08:10AM
DerAlbi, I do NOT have 'big plans in mind' for some super coilgun with some monster puck SCR. I would have to be insane to throw together a coil and power it with 10's of kJ with a 56kA SCR. This is the impression you give the readers!
FYI: I asked about the use of other (than electrolytic) types of capacitor in coilguns such as energy / pulse caps, with the latter stages of a multi-stage coilgun in mind. As the projectile is then moving very fast and perhaps needed the energizing best applied by a fast discharge capacitor. The point was leading up to whether there becomes a stage where increased efficiency requires a faster type capacitor that could dump a greater percentage of it's energy (thus increased efficiency) into accelerating the projectile. My thought was that at this point an electrolytic cap would barely discharge (crippling efficiency). your harsh words discourage my continuing...
You seem experienced and your words seem wise, why don't you use them in a more positive manner instead of using this jump-the-gun to a (self-described) "raging and crying" style. Nobody gains from that.
Signification, Sun Feb 22 2015, 08:10AM
DerAlbi, I do NOT have 'big plans in mind' for some super coilgun with some monster puck SCR. I would have to be insane to throw together a coil and power it with 10's of kJ with a 56kA SCR. This is the impression you give the readers!
FYI: I asked about the use of other (than electrolytic) types of capacitor in coilguns such as energy / pulse caps, with the latter stages of a multi-stage coilgun in mind. As the projectile is then moving very fast and perhaps needed the energizing best applied by a fast discharge capacitor. The point was leading up to whether there becomes a stage where increased efficiency requires a faster type capacitor that could dump a greater percentage of it's energy (thus increased efficiency) into accelerating the projectile. My thought was that at this point an electrolytic cap would barely discharge (crippling efficiency). your harsh words discourage my continuing...
You seem experienced and your words seem wise, why don't you use them in a more positive manner instead of using this jump-the-gun to a (self-described) "raging and crying" style. Nobody gains from that.
Re: large coil gun
DerAlbi, Sun Feb 22 2015, 01:53PM
I cant use my knowledge here in a much positive way because i did research and experiments that can describe optimization of a CG.. but i cant tell anyone "this must be so, and this should be like this etc". Who here actually could do some advanced FEM or even knows what the cross correlation of Coilcurrent and potential coil force means physically. Its just hard to teach, when the most basic caluclations are avoided because they are too hard. Even more, if you can only write about it
But dont be discuraged - at least not much. Its ok, if you take a step back and notice "there is a guy raging about SCR users - could he be right; what can i do?"
Answer: Math.
You worry about stuff thats way ahead of you. May i ask for reasons? I mean: who needs low ESL (what impact would it have - this can be calculated), The same is with the ESR.
You just talk about the "later stages" Even at 100m/s and "only" 2cm Projectile length the time scale is still 200us. You know how fucking long that actually is for the order of magnitude where parasitic effects are?
The ESR of the Cap: do you know how low 10..50mOhm actually are in comparision to your coil or the differential resistance of a SCR?
Your worries are good - you NEED to know what CAN go wrong. But the consequences are not be best: you immediately look out for material... but what is actually good enough? That what others say? No. From your design goal comes directly a specification what will be good enough. This IS the hard part of the project.
Dont take it as an offense
I started out exactly the same. Now i am heading for 35-40% eff and my highes current is only 700A... kind of crazy, issnt it? Parasitics? Yes, extremely important! But only where they are actually at work and causing issues.
I concluded from your way of acting in the forum, that you are enthousiastic like hell. Having a thought everywhere - reviving dead threads because thoughts just jump around making it impossible to actually watch for Threads-Dates... and it shows that you are willing to study - because you use the forum search to dig out these threads and you actually read them! Thats GOOOD! If i have taken a little peak of your motivation then i am glad to help, you are now much more productive state - you are able to focus on the important stuff and determine if you really have a goal or just the mood to build a CG
Really: i am offering my help by questioning your fears. First show me a basic calculation that shows the relevance and thats it.
For basic ball park figures its often enough to know
Resistance R = U/I;
Inductance I = U*dt/L
Capacitance: U = I*dt/C
If you determine that your ESR has only 10-20% impact? who cares.
If you determine that your ESL reduces voltage by 100V? Who cares? Back EMF reduces your voltage by U = F*v/I (What is F_orce? -> FEM, v is your planed velocity, and I is your peak current) are thes 100V still important? Until you dont know the answers... you know what i mean?
DerAlbi, Sun Feb 22 2015, 01:53PM
I cant use my knowledge here in a much positive way because i did research and experiments that can describe optimization of a CG.. but i cant tell anyone "this must be so, and this should be like this etc". Who here actually could do some advanced FEM or even knows what the cross correlation of Coilcurrent and potential coil force means physically. Its just hard to teach, when the most basic caluclations are avoided because they are too hard. Even more, if you can only write about it
But dont be discuraged - at least not much. Its ok, if you take a step back and notice "there is a guy raging about SCR users - could he be right; what can i do?"
Answer: Math.
You worry about stuff thats way ahead of you. May i ask for reasons? I mean: who needs low ESL (what impact would it have - this can be calculated), The same is with the ESR.
You just talk about the "later stages" Even at 100m/s and "only" 2cm Projectile length the time scale is still 200us. You know how fucking long that actually is for the order of magnitude where parasitic effects are?
The ESR of the Cap: do you know how low 10..50mOhm actually are in comparision to your coil or the differential resistance of a SCR?
Your worries are good - you NEED to know what CAN go wrong. But the consequences are not be best: you immediately look out for material... but what is actually good enough? That what others say? No. From your design goal comes directly a specification what will be good enough. This IS the hard part of the project.
Dont take it as an offense
I started out exactly the same. Now i am heading for 35-40% eff and my highes current is only 700A... kind of crazy, issnt it? Parasitics? Yes, extremely important! But only where they are actually at work and causing issues.I concluded from your way of acting in the forum, that you are enthousiastic like hell. Having a thought everywhere - reviving dead threads because thoughts just jump around making it impossible to actually watch for Threads-Dates... and it shows that you are willing to study - because you use the forum search to dig out these threads and you actually read them! Thats GOOOD! If i have taken a little peak of your motivation then i am glad to help, you are now much more productive state - you are able to focus on the important stuff and determine if you really have a goal or just the mood to build a CG
Really: i am offering my help by questioning your fears. First show me a basic calculation that shows the relevance and thats it.
For basic ball park figures its often enough to know
Resistance R = U/I;
Inductance I = U*dt/L
Capacitance: U = I*dt/C
If you determine that your ESR has only 10-20% impact? who cares.
If you determine that your ESL reduces voltage by 100V? Who cares? Back EMF reduces your voltage by U = F*v/I (What is F_orce? -> FEM, v is your planed velocity, and I is your peak current) are thes 100V still important? Until you dont know the answers... you know what i mean?
Re: large coil gun
hen918, Sun Feb 22 2015, 08:40PM
You are right. But, you could be less condescending! Maybe he just wants to make a coil-gun. Maybe his goal was not to make the highest efficiency one ever. Maybe, like I, he would love to spend some time going through the math(s) and design and make a really highly efficient coil-gun but has other stuff to be getting on with.
hen918, Sun Feb 22 2015, 08:40PM
DerAlbi wrote ...
I cant use my knowledge here in a much positive way because i did research and experiments that can describe optimization of a CG.. but i cant tell anyone "this must be so, and this should be like this etc". Who here actually could do some advanced FEM or even knows what the cross correlation of Coilcurrent and potential coil force means physically. Its just hard to teach, when the most basic caluclations are avoided because they are too hard. Even more, if you can only write about it
But dont be discuraged - at least not much. Its ok, if you take a step back and notice "there is a guy raging about SCR users - could he be right; what can i do?"
Answer: Math.
You worry about stuff thats way ahead of you. May i ask for reasons? I mean: who needs low ESL (what impact would it have - this can be calculated), The same is with the ESR.
You just talk about the "later stages" Even at 100m/s and "only" 2cm Projectile length the time scale is still 200us. You know how fucking long that actually is for the order of magnitude where parasitic effects are?
The ESR of the Cap: do you know how low 10..50mOhm actually are in comparision to your coil or the differential resistance of a SCR?
Your worries are good - you NEED to know what CAN go wrong. But the consequences are not be best: you immediately look out for material... but what is actually good enough? That what others say? No. From your design goal comes directly a specification what will be good enough. This IS the hard part of the project.
Dont take it as an offense I started out exactly the same. Now i am heading for 35-40% eff and my highes current is only 700A... kind of crazy, issnt it? Parasitics? Yes, extremely important! But only where they are actually at work and causing issues.
I concluded from your way of acting in the forum, that you are enthousiastic like hell. Having a thought everywhere - reviving dead threads because thoughts just jump around making it impossible to actually watch for Threads-Dates... and it shows that you are willing to study - because you use the forum search to dig out these threads and you actually read them! Thats GOOOD! If i have taken a little peak of your motivation then i am glad to help, you are now much more productive state - you are able to focus on the important stuff and determine if you really have a goal or just the mood to build a CG
Really: i am offering my help by questioning your fears. First show me a basic calculation that shows the relevance and thats it.
For basic ball park figures its often enough to know
Resistance R = U/I;
Inductance I = U*dt/L
Capacitance: U = I*dt/C
If you determine that your ESR has only 10-20% impact? who cares.
If you determine that your ESL reduces voltage by 100V? Who cares? Back EMF reduces your voltage by U = F*v/I (What is F_orce? -> FEM, v is your planed velocity, and I is your peak current) are thes 100V still important? Until you dont know the answers... you know what i mean?
I cant use my knowledge here in a much positive way because i did research and experiments that can describe optimization of a CG.. but i cant tell anyone "this must be so, and this should be like this etc". Who here actually could do some advanced FEM or even knows what the cross correlation of Coilcurrent and potential coil force means physically. Its just hard to teach, when the most basic caluclations are avoided because they are too hard. Even more, if you can only write about it
But dont be discuraged - at least not much. Its ok, if you take a step back and notice "there is a guy raging about SCR users - could he be right; what can i do?"
Answer: Math.
You worry about stuff thats way ahead of you. May i ask for reasons? I mean: who needs low ESL (what impact would it have - this can be calculated), The same is with the ESR.
You just talk about the "later stages" Even at 100m/s and "only" 2cm Projectile length the time scale is still 200us. You know how fucking long that actually is for the order of magnitude where parasitic effects are?
The ESR of the Cap: do you know how low 10..50mOhm actually are in comparision to your coil or the differential resistance of a SCR?
Your worries are good - you NEED to know what CAN go wrong. But the consequences are not be best: you immediately look out for material... but what is actually good enough? That what others say? No. From your design goal comes directly a specification what will be good enough. This IS the hard part of the project.
Dont take it as an offense
I started out exactly the same. Now i am heading for 35-40% eff and my highes current is only 700A... kind of crazy, issnt it? Parasitics? Yes, extremely important! But only where they are actually at work and causing issues.I concluded from your way of acting in the forum, that you are enthousiastic like hell. Having a thought everywhere - reviving dead threads because thoughts just jump around making it impossible to actually watch for Threads-Dates... and it shows that you are willing to study - because you use the forum search to dig out these threads and you actually read them! Thats GOOOD! If i have taken a little peak of your motivation then i am glad to help, you are now much more productive state - you are able to focus on the important stuff and determine if you really have a goal or just the mood to build a CG
Really: i am offering my help by questioning your fears. First show me a basic calculation that shows the relevance and thats it.
For basic ball park figures its often enough to know
Resistance R = U/I;
Inductance I = U*dt/L
Capacitance: U = I*dt/C
If you determine that your ESR has only 10-20% impact? who cares.
If you determine that your ESL reduces voltage by 100V? Who cares? Back EMF reduces your voltage by U = F*v/I (What is F_orce? -> FEM, v is your planed velocity, and I is your peak current) are thes 100V still important? Until you dont know the answers... you know what i mean?
You are right. But, you could be less condescending! Maybe he just wants to make a coil-gun. Maybe his goal was not to make the highest efficiency one ever. Maybe, like I, he would love to spend some time going through the math(s) and design and make a really highly efficient coil-gun but has other stuff to be getting on with.
Re: large coil gun
Signification, Sun Feb 22 2015, 08:48PM
First: you grossly misjudge me...
and it seems what you are saying is, 'this is not the place to learn', and since you view yourself as *advanced*, you don't have to help anyone. Your logic makes no sense. Instead of all the criticism, why don't you just offer that help or say nothing?
Signification, Sun Feb 22 2015, 08:48PM
First: you grossly misjudge me...
and it seems what you are saying is, 'this is not the place to learn', and since you view yourself as *advanced*, you don't have to help anyone. Your logic makes no sense. Instead of all the criticism, why don't you just offer that help or say nothing?
Re: large coil gun
DerAlbi, Sun Feb 22 2015, 08:52PM
Right. maybe its just my cry and my frustration that i have basically noone to work with above a certain level.
I understand, its a nice fun project but it can become art.
And i often get the feeling that most people see it as art whatever they do. i seem to be easily offended by this
@ Sig: of course i may misjudge.. its the internet. i can only watch for signs and interpret them in my way.
"this is not the place to learn". no no, its not the place to teach. its just not possible with people who avoid basic equations. (that does not implie you, its more general) As a fun project most people do not want the uncool stuff. Cant you understand this hopeless situation everyone is in who is actually educated in electronics? If you cant even relie on basic knowledge of Ohms Law.. where to start? And people tend to want to fly to the moon with their designs... basically you need to give others a perfect solution . if not, you are a bad person hard to do that.
For my part i would really be interested in your calculations and double check them - no problem. Then lets discuss the parasitics and what you can expect and idendify the problems that actually exist. It first starts with a specification: what do you want to achieve.
DerAlbi, Sun Feb 22 2015, 08:52PM
Right. maybe its just my cry and my frustration that i have basically noone to work with above a certain level.
I understand, its a nice fun project but it can become art.
And i often get the feeling that most people see it as art whatever they do. i seem to be easily offended by this
@ Sig: of course i may misjudge.. its the internet. i can only watch for signs and interpret them in my way.
"this is not the place to learn". no no, its not the place to teach. its just not possible with people who avoid basic equations. (that does not implie you, its more general) As a fun project most people do not want the uncool stuff. Cant you understand this hopeless situation everyone is in who is actually educated in electronics? If you cant even relie on basic knowledge of Ohms Law.. where to start? And people tend to want to fly to the moon with their designs... basically you need to give others a perfect solution . if not, you are a bad person
hard to do that.For my part i would really be interested in your calculations and double check them - no problem. Then lets discuss the parasitics and what you can expect and idendify the problems that actually exist. It first starts with a specification: what do you want to achieve.
Re: large coil gun
hen918, Sun Feb 22 2015, 09:15PM
You may misjudge, but if you think there is a possibility of misjudgement you should refrain from comments like that.
hen918, Sun Feb 22 2015, 09:15PM
DerAlbi wrote ...
...
"this is not the place to learn". no no, its not the place to teach. its just not possible with people who avoid basic equations.
...
Bollocks. I, for one, enjoy equations. You seem to be assuming nobody wants to learn on this forum....
"this is not the place to learn". no no, its not the place to teach. its just not possible with people who avoid basic equations.
...
You may misjudge, but if you think there is a possibility of misjudgement you should refrain from comments like that.
Re: large coil gun
Signification, Sun Feb 22 2015, 09:44PM
hen918, exactly! I love equations --and more so, learning their meaning deeply enough to apply them practically (I think this is obvious through my posts). My degree is in physics, BUT if I even made a 'B' on any math test, I considered it somewhat a failure since there was something I was not getting. Above all: I want to understand why something works -or fails-
I am new here, but will adjust to any rules--I NEVER saw a problem until DerAlbi apparently got me thinking maybe I am on the wrong forum (with every single reply to me!). I came here to learn as much as teach--and enjoy. I will *very carefully* re-read the rules and in the meantime post a bit less frequently.
Signification, Sun Feb 22 2015, 09:44PM
hen918, exactly! I love equations --and more so, learning their meaning deeply enough to apply them practically (I think this is obvious through my posts). My degree is in physics, BUT if I even made a 'B' on any math test, I considered it somewhat a failure since there was something I was not getting. Above all: I want to understand why something works -or fails-
I am new here, but will adjust to any rules--I NEVER saw a problem until DerAlbi apparently got me thinking maybe I am on the wrong forum (with every single reply to me!). I came here to learn as much as teach--and enjoy. I will *very carefully* re-read the rules and in the meantime post a bit less frequently.
Re: large coil gun
DerAlbi, Sun Feb 22 2015, 09:54PM
hen918: You are obviously here to contibute, not to ask Thats not what most Threadstarters in the EM-Accel.-Forum do... 
Just listing the topics:
72MJ escape velocity, storage for 5 hours on mains: wishfull thinking.
2.4Kj to play with....: first ordered parts then searched a project for the Caps. Beginner.
Brooks coil: its an ok thought.
Coils - contract or expand?: holy...
"GAUSS CONTROL": if current measurement is expensive, its done wrong.
Parallel coil-layers?: "bored guy", but not willing to search how inductance behaves in coupled inductors?
Induction launcher experiments: belong in the project section.
Coilgun - 1 long 1 layer coil as long as the barrel? Good, Bad?: Has not done basic reading about the topic.
flat copper coil...?: asks basically, if he should do an experiment to learn something. ??
Circular railgun?: good one. Its BigBad. Hes great.
action integtal: good start but no information why its considered...
Pulse D optimizations: asks for complex optimization. Just a quote: "What im trying to workout is, with more volts more amps are produced from a cap, but the joules increase by power." What?
Capacitor charger for multi stage coilgun: again a ZVS deriviation. And it will just blow up.
Low Voltage Capacitor ETG: Hasnt read the basics of what he want to do. He googled not longer for 10min.
Infrared trigger circuit: has problems with rebuilding a given design.
Shall i continue? Its nice that YOU are good.. But YOU are then not the person my posts relate to. Pick a topic that gives you hard reasons to be discussed. You notice that you will need to be picky.
Sig: then show the stuff you think about in math language! I am interested - really!
DerAlbi, Sun Feb 22 2015, 09:54PM
hen918: You are obviously here to contibute, not to ask
Thats not what most Threadstarters in the EM-Accel.-Forum do... Just listing the topics:
72MJ escape velocity, storage for 5 hours on mains: wishfull thinking.
2.4Kj to play with....: first ordered parts then searched a project for the Caps. Beginner.
Brooks coil: its an ok thought.
Coils - contract or expand?: holy...
"GAUSS CONTROL": if current measurement is expensive, its done wrong.
Parallel coil-layers?: "bored guy", but not willing to search how inductance behaves in coupled inductors?
Induction launcher experiments: belong in the project section.
Coilgun - 1 long 1 layer coil as long as the barrel? Good, Bad?: Has not done basic reading about the topic.
flat copper coil...?: asks basically, if he should do an experiment to learn something. ??
Circular railgun?: good one. Its BigBad. Hes great.
action integtal: good start but no information why its considered...
Pulse D optimizations: asks for complex optimization. Just a quote: "What im trying to workout is, with more volts more amps are produced from a cap, but the joules increase by power." What?
Capacitor charger for multi stage coilgun: again a ZVS deriviation. And it will just blow up.
Low Voltage Capacitor ETG: Hasnt read the basics of what he want to do. He googled not longer for 10min.
Infrared trigger circuit: has problems with rebuilding a given design.
Shall i continue? Its nice that YOU are good..
But YOU are then not the person my posts relate to. Pick a topic that gives you hard reasons to be discussed. You notice that you will need to be picky.Sig: then show the stuff you think about in math language! I am interested - really!
Re: large coil gun
Signification, Sun Feb 22 2015, 10:07PM
DerAlbi, Simply look through my 'forum posts'...as may anyone else, and you will find it. now...
ENOUGH!!
TIME TO END THIS!!
I have constructive things to do.
Signification, Sun Feb 22 2015, 10:07PM
DerAlbi, Simply look through my 'forum posts'...as may anyone else, and you will find it. now...
ENOUGH!!
TIME TO END THIS!!
I have constructive things to do.
Re: large coil gun
Uspring, Mon Feb 23 2015, 09:59AM
DerAlbi wrote:
Uspring, Mon Feb 23 2015, 09:59AM
DerAlbi wrote:
Who here actually could do some advanced FEM or even knows what the cross correlation of Coilcurrent and potential coil force means physically.A number of us. The statement about cross correlation is somewhat opaque. Cross correlations are usually used in statistics. Integrals over products of functions in the context here should be named differently.
Re: large coil gun
Signification, Tue Feb 24 2015, 08:39PM
DerAlbi, This is my first attempt at applying the concept of cross correlation with coilgun parameters (the two you specify), but I will try to mathematically connect the two:
We are concerned with these two given cross correlation coilgun functions:
Function 1: "Coil current"
Let's call it I(t) this could be a couple of things. Of the two in mind, I will assume it means STEADY current, i. Not a pulse flowing through the "coil".
Function 2: "potential coil force"
This one's a bit more complex. First let's assume this energized coil creates a steady magnetic FORCE field (B-field), and add the constraint that the only significant B-field is that which occupies the inner core (barrel) and protrudes beyond each end for about 1/2 the length of the barrel. This is what we will consider the VOLUME of your "potential coil force" field. Since we must primarily consider FORCE, how is force mathematically related to the B-field? Consider the -magnetic field energy density- of this B-field volume--call it 'E'. From physics, E is proportional to the square of the field strength B; specifically:
*** E = [1/(2*uo)] * (B^2) {joules per cubic meter} ***
We'll just say "E is proportional to the square of the B-field intensity" To get at the desired force, F, requires a directional derivative. Because we are only considering the direction along the barrel axis (say, the x-axis), this becomes a single variable derivative. Mathematically, the force may now be written as the rate of change of the square of B, or,
F[b] = (k) * d/dx(B^2) Newtons; where k is a constant.
=============================
Finally, The cross correlation functions are: I(t)= i (Amps) and F[b] = (k) * d/dx(B^2) Newtons.
If a specific case defining the variables of these functions are given, we could plot the force exerted on a "particle" (of negligible effect on B) by your "potential coil force" as it Lags along the coil axis in the 'force field' created by your "coil current".
Signification, Tue Feb 24 2015, 08:39PM
DerAlbi, This is my first attempt at applying the concept of cross correlation with coilgun parameters (the two you specify), but I will try to mathematically connect the two:
We are concerned with these two given cross correlation coilgun functions:
Function 1: "Coil current"
Let's call it I(t) this could be a couple of things. Of the two in mind, I will assume it means STEADY current, i. Not a pulse flowing through the "coil".
Function 2: "potential coil force"
This one's a bit more complex. First let's assume this energized coil creates a steady magnetic FORCE field (B-field), and add the constraint that the only significant B-field is that which occupies the inner core (barrel) and protrudes beyond each end for about 1/2 the length of the barrel. This is what we will consider the VOLUME of your "potential coil force" field. Since we must primarily consider FORCE, how is force mathematically related to the B-field? Consider the -magnetic field energy density- of this B-field volume--call it 'E'. From physics, E is proportional to the square of the field strength B; specifically:
*** E = [1/(2*uo)] * (B^2) {joules per cubic meter} ***
We'll just say "E is proportional to the square of the B-field intensity" To get at the desired force, F, requires a directional derivative. Because we are only considering the direction along the barrel axis (say, the x-axis), this becomes a single variable derivative. Mathematically, the force may now be written as the rate of change of the square of B, or,
F[b] = (k) * d/dx(B^2) Newtons; where k is a constant.
=============================
Finally, The cross correlation functions are: I(t)= i (Amps) and F[b] = (k) * d/dx(B^2) Newtons.
If a specific case defining the variables of these functions are given, we could plot the force exerted on a "particle" (of negligible effect on B) by your "potential coil force" as it Lags along the coil axis in the 'force field' created by your "coil current".
Re: large coil gun
DerAlbi, Wed Feb 25 2015, 02:06AM
There is no analytical solution to this problem. Inventing Force-Field is more something for StarTreck
Coil force behaves like this
F(x):= -a*x^(1+n1) * exp[ b * |x|^(3+n2) ] with
a: depends on the current you have while you make a projectile position (=x) sweep.
b: depends on your coil gemometry
n1,n2: correction factors, depending also on coilgeometry. should be close to 0.
If you normalize this function to a maximum of 1 you get the percentage of force that a coil can do. You basically get a graph where the coil is most efficient because the same current gives you the most pullforce. a,b,n can be determined by LeastSquares. of a FEM simulation.
The goal is now to find a realizable (Current-)function that (when quared and normalized also to 1) maximizes the cross correlation at zero. Then you got the highest energy transfer you can have. Of yourse you get a y-mirrored Stepfunction (going from 1 to 0 at x=0) for the current, that cant be realized. So one can throw in a resistive loss term (proportional to I³) and maximize efficiency too.
Of course then the current will be 0. So what you do is actually maximizing Efficieny^n * Force.Current²Integral. with n > 1..3 whatever priority you give to efficiency.
But seriously: with SCR designs... you have virtually no way for current pulse shaping. So its not even worth thinking about it. if you get 2% eff or 4%... who cares. Youtube cares only for design, technical stuff doesnt matter as long one destrys stuff that is fragile anyway
DerAlbi, Wed Feb 25 2015, 02:06AM
There is no analytical solution to this problem. Inventing Force-Field is more something for StarTreck
Coil force behaves like this
F(x):= -a*x^(1+n1) * exp[ b * |x|^(3+n2) ] with
a: depends on the current you have while you make a projectile position (=x) sweep.
b: depends on your coil gemometry
n1,n2: correction factors, depending also on coilgeometry. should be close to 0.
If you normalize this function to a maximum of 1 you get the percentage of force that a coil can do. You basically get a graph where the coil is most efficient because the same current gives you the most pullforce. a,b,n can be determined by LeastSquares. of a FEM simulation.
The goal is now to find a realizable (Current-)function that (when quared and normalized also to 1) maximizes the cross correlation at zero. Then you got the highest energy transfer you can have. Of yourse you get a y-mirrored Stepfunction (going from 1 to 0 at x=0) for the current, that cant be realized. So one can throw in a resistive loss term (proportional to I³) and maximize efficiency too.
Of course then the current will be 0. So what you do is actually maximizing Efficieny^n * Force.Current²Integral. with n > 1..3 whatever priority you give to efficiency.
But seriously: with SCR designs... you have virtually no way for current pulse shaping. So its not even worth thinking about it. if you get 2% eff or 4%... who cares. Youtube cares only for design, technical stuff doesnt matter as long one destrys stuff that is fragile anyway
Re: large coil gun
BigBad, Wed Feb 25 2015, 12:31PM
You would have a point except... multistage. Even some suckback isn't directly lossy, only to the extent it indirectly creates coil and other resistance losses, but resistive losses, as a percentage, go down as speed increases.
basically with coilguns multistage > all other tricks
BigBad, Wed Feb 25 2015, 12:31PM
You would have a point except... multistage. Even some suckback isn't directly lossy, only to the extent it indirectly creates coil and other resistance losses, but resistive losses, as a percentage, go down as speed increases.
basically with coilguns multistage > all other tricks
Re: large coil gun
DerAlbi, Wed Feb 25 2015, 05:55PM
You are totally right Actually multistage is kind of the only thing where this is advantageous usable.. multistage halfbridges, awwww <3
DerAlbi, Wed Feb 25 2015, 05:55PM
You are totally right
Actually multistage is kind of the only thing where this is advantageous usable.. multistage halfbridges, awwww <3Re: large coil gun
Uspring, Thu Feb 26 2015, 09:40AM
Probably a faq: Couldn't a high efficiency coil gun be made with a transmission line creating a traveling magnetic pulse? Would require a lot of caps, but electronics would be simple.
Uspring, Thu Feb 26 2015, 09:40AM
Probably a faq: Couldn't a high efficiency coil gun be made with a transmission line creating a traveling magnetic pulse? Would require a lot of caps, but electronics would be simple.
Re: large coil gun
DerAlbi, Thu Feb 26 2015, 04:32PM
Here we go. Have you done any Thinking before proposing this? (if so, why dont you at least try to answer it yourself and present your thoughts?)
First of all a transmission line propagates electromagnetic waves. Thats a magnetic field entangeled with an electric field.
-> So what exactly do you think would be the propellant force ? At least pushed or pulled? Magnetic or electric?
-> how do you think to jump on a wave that travels near light speed? (You really think thats like suring on water??)
- have you thought about which frequencies yould you use ? At multiple THz... such as light - you can kick electrons and apply a small force on reflecting surfaces. Since you know that there infact are standong towers of steel and iron which are used to transmit medium wave radio without beeing crushed.......
......
- even more interesting: what makes you think this would be specially high efficient??? If you have this intuition, why you hold back the scientific basis for this in your post? let us know what you think and why you think.
Thats exactly what i was raging above -.-
If thats a faq, then we should include "how to open dors".
DerAlbi, Thu Feb 26 2015, 04:32PM
Here we go. Have you done any Thinking before proposing this? (if so, why dont you at least try to answer it yourself and present your thoughts?)
First of all a transmission line propagates electromagnetic waves. Thats a magnetic field entangeled with an electric field.
-> So what exactly do you think would be the propellant force ? At least pushed or pulled? Magnetic or electric?
-> how do you think to jump on a wave that travels near light speed? (You really think thats like suring on water??)
- have you thought about which frequencies yould you use ? At multiple THz... such as light - you can kick electrons and apply a small force on reflecting surfaces. Since you know that there infact are standong towers of steel and iron which are used to transmit medium wave radio without beeing crushed.......
......
- even more interesting: what makes you think this would be specially high efficient??? If you have this intuition, why you hold back the scientific basis for this in your post? let us know what you think and why you think.
Thats exactly what i was raging above -.-
If thats a faq, then we should include "how to open dors".
Re: large coil gun
Shrad, Thu Feb 26 2015, 06:33PM
that's my suggestion of magnetic pulse compression with a hybrid coilgun/railgun where the solenoid would be the rail and the projectile would short the solenoid to compress the magnetic pulse
you could also use a coaxial deionized water pulse capacitor using the breakdown voltage of the capacitor itself as a spark gap for the thing
the difficulty would be to machine the solenoid rail with turns spaced closely enough to achieve a dense flux
EDIT:
for reference
having talked with the guy (who would actually love this forum) I think the idea is not that bad and if someone would be able to do it he would be in the lot
Shrad, Thu Feb 26 2015, 06:33PM
Uspring wrote ...
Probably a faq: Couldn't a high efficiency coil gun be made with a transmission line creating a traveling magnetic pulse? Would require a lot of caps, but electronics would be simple.
Probably a faq: Couldn't a high efficiency coil gun be made with a transmission line creating a traveling magnetic pulse? Would require a lot of caps, but electronics would be simple.
that's my suggestion of magnetic pulse compression with a hybrid coilgun/railgun where the solenoid would be the rail and the projectile would short the solenoid to compress the magnetic pulse
you could also use a coaxial deionized water pulse capacitor using the breakdown voltage of the capacitor itself as a spark gap for the thing
the difficulty would be to machine the solenoid rail with turns spaced closely enough to achieve a dense flux
EDIT:
for reference
having talked with the guy (who would actually love this forum) I think the idea is not that bad and if someone would be able to do it he would be in the lot
Re: large coil gun
DerAlbi, Thu Feb 26 2015, 06:40PM
Shrad, what you describe is could be interesting - can you draw a pricture just to make sure there is no missunderstanding?
And no, thats not Usprings version What you describe is in no way a transmission line for EM waves.
What i dont see in a Rail-/Coil-gun hybrid, how the projectile would look like. Railguns (commonly) dont use ferromagnetic projectiles while Coilguns depend on it.
DerAlbi, Thu Feb 26 2015, 06:40PM
Shrad, what you describe is could be interesting - can you draw a pricture just to make sure there is no missunderstanding?
And no, thats not Usprings version
What you describe is in no way a transmission line for EM waves.What i dont see in a Rail-/Coil-gun hybrid, how the projectile would look like. Railguns (commonly) dont use ferromagnetic projectiles while Coilguns depend on it.
Re: large coil gun
Shrad, Thu Feb 26 2015, 07:16PM
this https://books.google.be/books?id=zmYrAAAAYAAJ&pg=PA157&lpg=PA157&dq=coaxial+water+capacitor&source=bl&ots=dYeRP9k-Oi&sig=l4Xdv27NyYk_9W7xqrreZCaOST4&hl=fr&sa=X&ei=P2fvVP-oGtDQ7AbwgoHIAg&ved=0CGAQ6AEwDQ#v=onepage&q=coaxial%20water%20capacitor&f=false states 1,7cm of transmission line length per nanosecond of discharge
due to the small value of L and high dI/dt it seems feasible to discharge megawatts in L and generate enough magnetic field during the discharge time
my setup would consist of two spiral coils in parallel, separated by an insulating material, with a coaxial capacitor surrounding it
connection of the outer capacitor plate to the red solenoid is done at the exit side, connection of the green solenoid is central plate body
it could be practical to be able to screw the red solenoid and insulator material in the grooved barrel for easy replacement
a preliminary coilgun of small power could be used to trigger the discharge without using the capacitor breakdown voltage, but water is self healing so it would be convenient
don't use that near your TV
Shrad, Thu Feb 26 2015, 07:16PM
this https://books.google.be/books?id=zmYrAAAAYAAJ&pg=PA157&lpg=PA157&dq=coaxial+water+capacitor&source=bl&ots=dYeRP9k-Oi&sig=l4Xdv27NyYk_9W7xqrreZCaOST4&hl=fr&sa=X&ei=P2fvVP-oGtDQ7AbwgoHIAg&ved=0CGAQ6AEwDQ#v=onepage&q=coaxial%20water%20capacitor&f=false states 1,7cm of transmission line length per nanosecond of discharge
due to the small value of L and high dI/dt it seems feasible to discharge megawatts in L and generate enough magnetic field during the discharge time
my setup would consist of two spiral coils in parallel, separated by an insulating material, with a coaxial capacitor surrounding it
connection of the outer capacitor plate to the red solenoid is done at the exit side, connection of the green solenoid is central plate body
it could be practical to be able to screw the red solenoid and insulator material in the grooved barrel for easy replacement
a preliminary coilgun of small power could be used to trigger the discharge without using the capacitor breakdown voltage, but water is self healing so it would be convenient
don't use that near your TV
Re: large coil gun
Shrad, Thu Feb 26 2015, 07:18PM
of course with a ferromagnetic projectile ;) or of a construction which would induce a reverse field with the small electrical path involved
Shrad, Thu Feb 26 2015, 07:18PM
of course with a ferromagnetic projectile ;) or of a construction which would induce a reverse field with the small electrical path involved
Re: large coil gun
Uspring, Thu Feb 26 2015, 07:56PM
DerAlbi wrote:
The inductances are solenoids arranged just as in a multi stage gun. The behaviour of this line is, that a pulse applied will travel down the line with the speed of 1/sqrt(L*C), where L and C are the inductances and capacitances per unit length. A projectile inside of the solenoid will see a travelling magnetic field and be accelerated if located at the tail end of the field pulse.
Uspring, Thu Feb 26 2015, 07:56PM
DerAlbi wrote:
-> So what exactly do you think would be the propellant force ? At least pushed or pulled? Magnetic or electric?A transmission line does not have to be a straight piece of wire or a pair of such. Think of a number of inductances connected in series. Between each inductance a capacitor is connected to ground. The first inductance is connected to a pulse generator. This constitutes a transmission line in the limit of many caps and inductances.
The inductances are solenoids arranged just as in a multi stage gun. The behaviour of this line is, that a pulse applied will travel down the line with the speed of 1/sqrt(L*C), where L and C are the inductances and capacitances per unit length. A projectile inside of the solenoid will see a travelling magnetic field and be accelerated if located at the tail end of the field pulse.
-> how do you think to jump on a wave that travels near light speed? (You really think thats like suring on water??)I've given the speed above. It can be adapted to any speed you like by choosing L and C appropriately. Speed can be made non uniform to account for the acceleration of the projectile.
- even more interesting: what makes you think this would be specially high efficient???The reason is, that I (perthaps falsely) believe, that only a small percentage of the energy in the magnetic field is conferred to the projectile. Possibly this is due to the fact, that the field has to be quenched in order to avoid suck back. In a transmission line type circuit, quenching wouldn't be needed.
Re: large coil gun
DerAlbi, Thu Feb 26 2015, 07:57PM
I dont see how a water capacitor can be used in a homade design.
The paper/book you linked describes a 80kJ pulse with a Cap made of 1670gal of Water. This makes an energy to weight ratio 80g/J. Electrolytics are 40x better than that. Foils not as much, but too lazy to dig for data.. i suspect a factor of 10..25 over water.
Unfortunately that makes it impractical.
btw: 1.7cm/ns is 1/60th of the speed of light.
Uspring:
First of all, a transmission line consosts of DISTRIBUTED components. There is no L and no C. ther is only a L/m and C/m. You are talking about a discrete delayline - ok so far.
Second: the reach the last delayelement the Pulse must go through every delayelement before. So in terms of source impedance the last coil is supplied with the summed ESR of all delayelements before. This cant be benefical. Specially given the point, that the last coils must actually conduct more current, than the first coils... thats kind of backwards.
DerAlbi, Thu Feb 26 2015, 07:57PM
I dont see how a water capacitor can be used in a homade design.
The paper/book you linked describes a 80kJ pulse with a Cap made of 1670gal of Water. This makes an energy to weight ratio 80g/J. Electrolytics are 40x better than that. Foils not as much, but too lazy to dig for data.. i suspect a factor of 10..25 over water.
Unfortunately that makes it impractical.
btw: 1.7cm/ns is 1/60th of the speed of light.
Uspring:
First of all, a transmission line consosts of DISTRIBUTED components. There is no L and no C. ther is only a L/m and C/m. You are talking about a discrete delayline - ok so far.
Second: the reach the last delayelement the Pulse must go through every delayelement before. So in terms of source impedance the last coil is supplied with the summed ESR of all delayelements before. This cant be benefical. Specially given the point, that the last coils must actually conduct more current, than the first coils... thats kind of backwards.
Re: large coil gun
Uspring, Thu Feb 26 2015, 08:36PM
Uspring, Thu Feb 26 2015, 08:36PM
Second: the reach the last delayelement the Pulse must go through every delayelement before. So in terms of source impedance the last coil is supplied with the summed ESR of all delayelements before.There is definitely a loss of energy per stage, a sort of exponential decay. But it has to be seen in relation to the loss of energy due to energy imparted to the projectile.
This cant be benefical. Specially given the point, that the last coils must actually conduct more current, than the first coils... thats kind of backwards.Why does the last coil have more current?
Re: large coil gun
DerAlbi, Thu Feb 26 2015, 09:52PM
Coilgun Basics: you need to keep the Amp*Turn constant.
Later coils need to energize faster due to higher projectile velocity. Therefore less inductance is allowed which can only be achieved by decrase of turns. If you want to keep your pullforce=Amp*Turns constant, you have to compensate this with higher current.
Anyway, if you go through the design, you end up in a conventional multistage design.
Because your exponential decay ... really.. its not driven by the energytransfer to the projectile.. its driven by ESR. Coilguns struggle with bad Efficiency, remember?
DerAlbi, Thu Feb 26 2015, 09:52PM
Coilgun Basics: you need to keep the Amp*Turn constant.
Later coils need to energize faster due to higher projectile velocity. Therefore less inductance is allowed which can only be achieved by decrase of turns. If you want to keep your pullforce=Amp*Turns constant, you have to compensate this with higher current.
Anyway, if you go through the design, you end up in a conventional multistage design.
Because your exponential decay ... really.. its not driven by the energytransfer to the projectile.. its driven by ESR. Coilguns struggle with bad Efficiency, remember?
Re: large coil gun
Shrad, Fri Feb 27 2015, 07:32AM
a water capacitor of a couple nanofarads can be done with two aluminum cylinders and nylon endcaps, as in the laser video I linked
if you use that capacitor and an inductor with the formed PFN designed so that the capacitor discharge time matches the line propagation, you have a discharge which is sustained during the whole travel of the projectile, if the projectile itself shorts the turns of the inductor you allow it to accelerate and keep flux strength high by discharging a decreasing energy in a decreasing value inductor
that's just an idea of course, which is far enough of classical designs so I can believe people would criticize, but it is primarily meant for discussing pulse compression and high power PFN
Shrad, Fri Feb 27 2015, 07:32AM
a water capacitor of a couple nanofarads can be done with two aluminum cylinders and nylon endcaps, as in the laser video I linked
if you use that capacitor and an inductor with the formed PFN designed so that the capacitor discharge time matches the line propagation, you have a discharge which is sustained during the whole travel of the projectile, if the projectile itself shorts the turns of the inductor you allow it to accelerate and keep flux strength high by discharging a decreasing energy in a decreasing value inductor
that's just an idea of course, which is far enough of classical designs so I can believe people would criticize, but it is primarily meant for discussing pulse compression and high power PFN
Re: large coil gun
Uspring, Fri Feb 27 2015, 10:46AM
Uspring, Fri Feb 27 2015, 10:46AM
Later coils need to energize faster due to higher projectile velocity. Therefore less inductance is allowed which can only be achieved by decrase of turns.As said, the TL should be non uniform in speed to accomodate for the acceleration, i.e. L*C should decrease to the end of the TL. Also the impedance of the line should be constant to avoid energy reflection. Impedance is sqrt(L/C). Together this implies a reduction of L and C by the same factor towards the end of the line. For a given pulse energy, this implies larger currents at the end and also lower energizing times. So a correct design automatically implies less inductance at the end.
If you want to keep your pullforce=Amp*Turns constant, you have to compensate this with higher current.I don't think a constant pull force is required.
Anyway, if you go through the design, you end up in a conventional multistage design.If you'd be able to recover the energy left in a stage after the projectile has gone through it, it would be the same.
Because your exponential decay ... really.. its not driven by the energytransfer to the projectile.. its driven by ESR. Coilguns struggle with bad Efficiency, remember?Possibly just because you don't recover the energy left in the coil after the projectile has gone through it. Is the Q of the coil without a projectile that low?
Re: large coil gun
DerAlbi, Fri Feb 27 2015, 01:49PM
Uspring you are missing an important point
Coilstages get more and more efficient with higher Projectile velocity. So basically the first stages suck. Even with a halfbridge the injector coils optimal switching points (Based on Force-I²-Correlation and optimization to Eff²*TransferedPower) gives a switching scheme that is basically that of an SCR-circuit. Efficiency is simulated to be about 8%.
In your discrete Delay-Line the propagating pulse energy can only be the left energy after the pulse. So connecting your coils in series could never achieve a higher eff than that of the initial stage! Ind it doesnt matter if you use a seperate injector system. The priciple is allways the same.
Usually the efficiency increases with projectile energy. Your eff. decreses with every stage. I would call that a design flaw.
Shrad:
the propagation delay is dictated by dielectric constant
How do you plan to slow down the pulse?
Getting down from 1/60 of the speed of light to even Mach 20 is a difference of 3 orders of magnitude.
you would maximize sqrt(L*C). The problem is, that C maximizes when L shrinks. (and vice versa) There is a practical limit to this. nothing you could influence or design with such freedom.
DerAlbi, Fri Feb 27 2015, 01:49PM
Uspring you are missing an important point
Coilstages get more and more efficient with higher Projectile velocity. So basically the first stages suck. Even with a halfbridge the injector coils optimal switching points (Based on Force-I²-Correlation and optimization to Eff²*TransferedPower) gives a switching scheme that is basically that of an SCR-circuit. Efficiency is simulated to be about 8%.
In your discrete Delay-Line the propagating pulse energy can only be the left energy after the pulse. So connecting your coils in series could never achieve a higher eff than that of the initial stage! Ind it doesnt matter if you use a seperate injector system. The priciple is allways the same.
Usually the efficiency increases with projectile energy. Your eff. decreses with every stage. I would call that a design flaw.
Shrad:
the propagation delay is dictated by dielectric constant
How do you plan to slow down the pulse?
Getting down from 1/60 of the speed of light to even Mach 20 is a difference of 3 orders of magnitude.
you would maximize sqrt(L*C). The problem is, that C maximizes when L shrinks. (and vice versa) There is a practical limit to this. nothing you could influence or design with such freedom.
Re: large coil gun
BigBad, Fri Feb 27 2015, 08:19PM
BigBad, Fri Feb 27 2015, 08:19PM
Uspring wrote ...
It depends whether you want a constant acceleration, or constant power acceleration. If the latter, performance is worse.If you want to keep your pullforce=Amp*Turns constant, you have to compensate this with higher current.I don't think a constant pull force is required.
Re: large coil gun
Uspring, Fri Feb 27 2015, 08:57PM
Say the first stage will convert 5% of the electrical energy into kinetic energy and say another 5% are lost due to ESR, eddies etc. The next stage will then get 90% of the initial pulse energy. Assuming similar efficiency and losses, pulse energy will be down to 81% after the second stage and so on. After e.g. ten stages pulse energy will be at 35%, i.e. 65% will be gone and half of that is kinetic energy.
Uspring, Fri Feb 27 2015, 08:57PM
In your discrete Delay-Line the propagating pulse energy can only be the left energy after the pulse. So connecting your coils in series could never achieve a higher eff than that of the initial stage!You lost me here. What is the "left energy after the pulse"?
Say the first stage will convert 5% of the electrical energy into kinetic energy and say another 5% are lost due to ESR, eddies etc. The next stage will then get 90% of the initial pulse energy. Assuming similar efficiency and losses, pulse energy will be down to 81% after the second stage and so on. After e.g. ten stages pulse energy will be at 35%, i.e. 65% will be gone and half of that is kinetic energy.
Re: large coil gun
DerAlbi, Fri Feb 27 2015, 09:33PM
Then think again about the amount of energy that you put in the first coil. There must allready be all the energy present for alle the later coils. so you actually push 100J into the coil instead of 10J. As a consequence you are DEEEEEEEP into saturation.. so lets correct your efficiency to 1%.
Now redo your calculation again. Well: You need to push even more energy! ..lets correct the efficiency figure to 0.5%... continue your loop...
DerAlbi, Fri Feb 27 2015, 09:33PM
Say the first stage will convert 5% of the electrical energy into kinetic energy and say another 5% are lost due to ESR, eddies etc.Wow, you imply 50% eff at the first tage. Same amount transfered as lost.... would be record allready! Redo your example and assume 5%.
Then think again about the amount of energy that you put in the first coil. There must allready be all the energy present for alle the later coils. so you actually push 100J into the coil instead of 10J. As a consequence you are DEEEEEEEP into saturation.. so lets correct your efficiency to 1%.
Now redo your calculation again. Well: You need to push even more energy! ..lets correct the efficiency figure to 0.5%... continue your loop...
Re: large coil gun
Uspring, Sat Feb 28 2015, 10:28AM
But I think, what you are getting at, is that not 90% of the electrical energy is left, right after the projectile has gone through, but much less due to coil resistance losses. A TL ccelerator would not make sense for a stage with e.g. Q<1. Is that the case?
Uspring, Sat Feb 28 2015, 10:28AM
Wow, you imply 50% eff at the first tage. Same amount transfered as lost.... would be record allready! Redo your example and assume 5%.No. Consider a single stage. A 100% electrical energy in. The projectile goes through. 90% electrical energy is left in the coil (5% resistive loss, 5% kinetic energy). The 90% are lost, since the projectile has gone through. Efficiency is 5%.
But I think, what you are getting at, is that not 90% of the electrical energy is left, right after the projectile has gone through, but much less due to coil resistance losses. A TL ccelerator would not make sense for a stage with e.g. Q<1. Is that the case?
Re: large coil gun
DerAlbi, Sat Feb 28 2015, 10:42AM
Efficiency is "Kinetic / (Heat+Kinectic)". therefore you have 50%.
Your 5% is a conversion efficiency (=KinecticOut/MagneticEnergyIn). And 5% would be a pretty poor design. (assume 10-20%)
I dont kow what qualitiy factor implies.. i dont have a reference frequency.
DerAlbi, Sat Feb 28 2015, 10:42AM
Efficiency is "Kinetic / (Heat+Kinectic)". therefore you have 50%.
Your 5% is a conversion efficiency (=KinecticOut/MagneticEnergyIn). And 5% would be a pretty poor design. (assume 10-20%)
I dont kow what qualitiy factor implies.. i dont have a reference frequency.
Re: large coil gun
Shrad, Sat Feb 28 2015, 12:15PM
you could use L and C as a pulse forming network, or even with a secondary L and C at the junction of the primary L and C to lengthen the pulse so its duration is equivalent to the ideal projectile velocity, and pulse gets sharper as primary L gets smaller
If I was able to machine such a double spiral barrel I would really love to try this out, as I think a PFN with a pulse compression would be the most optimized design for a magnetically launched projectile
a bit like an electric trebuchet...
Shrad, Sat Feb 28 2015, 12:15PM
DerAlbi wrote ...
Shrad:
the propagation delay is dictated by dielectric constant
How do you plan to slow down the pulse?
Getting down from 1/60 of the speed of light to even Mach 20 is a difference of 3 orders of magnitude.
you would maximize sqrt(L*C). The problem is, that C maximizes when L shrinks. (and vice versa) There is a practical limit to this. nothing you could influence or design with such freedom.
Shrad:
the propagation delay is dictated by dielectric constant
How do you plan to slow down the pulse?
Getting down from 1/60 of the speed of light to even Mach 20 is a difference of 3 orders of magnitude.
you would maximize sqrt(L*C). The problem is, that C maximizes when L shrinks. (and vice versa) There is a practical limit to this. nothing you could influence or design with such freedom.
you could use L and C as a pulse forming network, or even with a secondary L and C at the junction of the primary L and C to lengthen the pulse so its duration is equivalent to the ideal projectile velocity, and pulse gets sharper as primary L gets smaller
If I was able to machine such a double spiral barrel I would really love to try this out, as I think a PFN with a pulse compression would be the most optimized design for a magnetically launched projectile
a bit like an electric trebuchet...
Re: large coil gun
Uspring, Sat Feb 28 2015, 12:30PM
Q is a measure of damping of a tank, i.e. describes the percentage of energy lost during a cycle. A higher Q implies less damping. If you, e.g. add a resistor R in series with the inductance of a tank, Q would be:
Q=2*pi*fres*L/R
Uspring, Sat Feb 28 2015, 12:30PM
Efficiency is "Kinetic / (Heat+Kinectic)". therefore you have 50%.Ideally you'd have a large B, when the projectile is at the point where dB/dx is largest and zero B, when the projectile is at the center of the coil. During this interval the energy stored by the magnetic field has to go somewhere. Is it dissipated in the coil resistance or does it return to the driving electronics? If the latter, is it recovered there or just burned up? If it is recovered you'd have 2 ways to define efficieny. Either kinetic energy/initial electric energy, or you could put the difference between before and after into the denominator.
Q is a measure of damping of a tank, i.e. describes the percentage of energy lost during a cycle. A higher Q implies less damping. If you, e.g. add a resistor R in series with the inductance of a tank, Q would be:
Q=2*pi*fres*L/R
Re: large coil gun
hen918, Sat Feb 28 2015, 06:55PM
what's happened to the capacitive elements?
hen918, Sat Feb 28 2015, 06:55PM
Uspring wrote ...
...
Q is a measure of damping of a tank, i.e. describes the percentage of energy lost during a cycle. A higher Q implies less damping. If you, e.g. add a resistor R in series with the inductance of a tank, Q would be:
Q=2*pi*fres*L/R
...
Q is a measure of damping of a tank, i.e. describes the percentage of energy lost during a cycle. A higher Q implies less damping. If you, e.g. add a resistor R in series with the inductance of a tank, Q would be:
Q=2*pi*fres*L/R
what's happened to the capacitive elements?
Re: large coil gun
Uspring, Sat Feb 28 2015, 07:20PM
You could write Q also as:
Q=sqrt(L/C)/R
using fres = 1/(2*pi*sqrt(L*C))
Uspring, Sat Feb 28 2015, 07:20PM
You could write Q also as:
Q=sqrt(L/C)/R
using fres = 1/(2*pi*sqrt(L*C))
Re: large coil gun
Signification, Mon Mar 02 2015, 10:04PM
Shrad, On the TEA laser you referenced (impressive construction BTW), will the laser work while the water is flowing? I was also wondering what the purpose is of the tube mounted on the back of the laser. ...looks like quite a divergent beam.
Signification, Mon Mar 02 2015, 10:04PM
Shrad, On the TEA laser you referenced (impressive construction BTW), will the laser work while the water is flowing? I was also wondering what the purpose is of the tube mounted on the back of the laser. ...looks like quite a divergent beam.
Re: large coil gun
Shrad, Tue Mar 03 2015, 08:14AM
I think it would pose no problem but this is pulsed as energy is stored in the tubes and repetition rate is quite low so there would not be a need to flow the water
the genius part of that build is that the water is used as a self healing dielectric which acts as a spark gap... and all is coaxial which is the best thing in pulse power
what makes me think that the solution is to combine pulse power and simplicity is that such a TEA is actually one of the highest power to complexity ratio, is scalable, reliable and resilient which makes huge powers possible
Shrad, Tue Mar 03 2015, 08:14AM
Signification wrote ...
Shrad, On the TEA laser you referenced (impressive construction BTW), will the laser work while the water is flowing? I was also wondering what the purpose is of the tube mounted on the back of the laser. ...looks like quite a divergent beam.
Shrad, On the TEA laser you referenced (impressive construction BTW), will the laser work while the water is flowing? I was also wondering what the purpose is of the tube mounted on the back of the laser. ...looks like quite a divergent beam.
I think it would pose no problem but this is pulsed as energy is stored in the tubes and repetition rate is quite low so there would not be a need to flow the water
the genius part of that build is that the water is used as a self healing dielectric which acts as a spark gap... and all is coaxial which is the best thing in pulse power
what makes me think that the solution is to combine pulse power and simplicity is that such a TEA is actually one of the highest power to complexity ratio, is scalable, reliable and resilient which makes huge powers possible
Re: large coil gun
DerAlbi, Tue Mar 03 2015, 08:49AM
And yet the only realistic thing about it is the talk. Boring. Specially when there are guys involved who stuggle to understand the basic optimization parameter/goal "efficiency"..
You guys suffer from denail. You are blended by your own confidence and ideas. Having allready figured out that the mechanics of the barrel is the biggest problem one seems to neglect everything else which is obvious if you just would touch the topics that dont fit into this positive thinking. thats not engineering thats... actually i have no word for this. Maybe a B and a S.
Just put forward at least something realistic. What about a simulation (LTSpice?) of your so called "transmission line" with real ESR in the coils (L/R = 1..3ms).
I know its worth avoiding reality.. having a dream is much easier than living in the real world.
If this "transmission line"-style thing works its for now not important what kind of capacitor or whatever you use. Its basic electronics still. So it can be simulated.
Sure you guys have allready the circuit and models in mind.. or what is your confidence based on? So upload it!
DerAlbi, Tue Mar 03 2015, 08:49AM
And yet the only realistic thing about it is the talk. Boring. Specially when there are guys involved who stuggle to understand the basic optimization parameter/goal "efficiency"..
You guys suffer from denail. You are blended by your own confidence and ideas. Having allready figured out that the mechanics of the barrel is the biggest problem one seems to neglect everything else which is obvious if you just would touch the topics that dont fit into this positive thinking. thats not engineering thats... actually i have no word for this. Maybe a B and a S.
Just put forward at least something realistic. What about a simulation (LTSpice?) of your so called "transmission line" with real ESR in the coils (L/R = 1..3ms).
I know its worth avoiding reality.. having a dream is much easier than living in the real world.
If this "transmission line"-style thing works its for now not important what kind of capacitor or whatever you use. Its basic electronics still. So it can be simulated.
Sure you guys have allready the circuit and models in mind.. or what is your confidence based on? So upload it!
Re: large coil gun
Uspring, Tue Mar 03 2015, 12:05PM
That being said, most of your comment is about the intellectual prowess of fellow 4hvians. This is not appropriate here and hardly understandable, since you had to be educated yourself about speeds in transmission lines, how they could be utilized in coil guns, Q values and the like.
Uspring, Tue Mar 03 2015, 12:05PM
L/R = 1..3msThat is indeed a very low value indicating a major energy loss in the time scale of the projectile traversing a stage. The stage looks more like a R-C circuit than like a L-C circuit. Energy recovery by a TL looks futile, if this value is correct.
That being said, most of your comment is about the intellectual prowess of fellow 4hvians. This is not appropriate here and hardly understandable, since you had to be educated yourself about speeds in transmission lines, how they could be utilized in coil guns, Q values and the like.
Re: large coil gun
Signification, Tue Mar 03 2015, 01:03PM
DerAlbi Wrote:
Unfortunately that makes it impractical.
btw: 1.7cm/ns is 1/60th of the speed of light.
---------------------------------------
I can't make this work, does anyone else get about 1/18th here?
Signification, Tue Mar 03 2015, 01:03PM
DerAlbi Wrote:
Unfortunately that makes it impractical.
btw: 1.7cm/ns is 1/60th of the speed of light.
---------------------------------------
I can't make this work, does anyone else get about 1/18th here?
Re: large coil gun
Shrad, Tue Mar 03 2015, 03:38PM
is the propagation speed tied to the bang energy? I thought that electrons would propagate uniformly based on the discharge path geometry rather than on the energy itself... I don't see why this wouldn't be reachable at home
anyway, we are here for sharing ideas I think, not to tell others that their idea is not good because they don't know the precise theory
a practical design has to be simple, straightforward and elegant, and those three key points are not part of rigid theory but come from confrontation of ideas... I do not value my theory understanding, but I value my ability to manipulate ideas in many configurations and take pleasure out of it, that's the only reason I take part to technical discussions apart for the pleasure of learning
Shrad, Tue Mar 03 2015, 03:38PM
is the propagation speed tied to the bang energy? I thought that electrons would propagate uniformly based on the discharge path geometry rather than on the energy itself... I don't see why this wouldn't be reachable at home
anyway, we are here for sharing ideas I think, not to tell others that their idea is not good because they don't know the precise theory
a practical design has to be simple, straightforward and elegant, and those three key points are not part of rigid theory but come from confrontation of ideas... I do not value my theory understanding, but I value my ability to manipulate ideas in many configurations and take pleasure out of it, that's the only reason I take part to technical discussions apart for the pleasure of learning
Re: large coil gun
DerAlbi, Tue Mar 03 2015, 04:55PM
Signification: You are correct, Typo in the calculator... good eye! But.. thats even worse
I dont see the point in discussing an idea thats obviously faulty just by considering the pricipals its based on. If one brings technical arguments against it and its completely ignored, there is no value in the discussion.
As i stated the Energy/Weight ratio is very unfortunate with water (so there is no point in using water as dielectric) and the whole thing with the propagation delay is questionable just by considering that you need to feed the energy through all the stages (you add up all the ESR along the path!).
If then these problems are not understood or dicussed away based on belief then i am full in my right to question someones... thought and more general the way of thinking.
Dont get me wrong.. BUT if your idea is questionable, then its your duty to resolve these questions. Thats done ONLY by hard evidece. Thats numbers or formulas or at least a numerical model [=simulation]. A good theory crushes all doubt easily. Everything else is more suited for the church.
"one could"... "one would"... "maybe".. is that tech-talk?
sry, in my opinion, thats youtube-comment level.
DerAlbi, Tue Mar 03 2015, 04:55PM
Signification: You are correct, Typo in the calculator... good eye! But..
thats even worse I dont see the point in discussing an idea thats obviously faulty just by considering the pricipals its based on. If one brings technical arguments against it and its completely ignored, there is no value in the discussion.
As i stated the Energy/Weight ratio is very unfortunate with water (so there is no point in using water as dielectric) and the whole thing with the propagation delay is questionable just by considering that you need to feed the energy through all the stages (you add up all the ESR along the path!).
If then these problems are not understood or dicussed away based on belief then i am full in my right to question someones... thought and more general the way of thinking.
Dont get me wrong.. BUT if your idea is questionable, then its your duty to resolve these questions. Thats done ONLY by hard evidece. Thats numbers or formulas or at least a numerical model [=simulation]. A good theory crushes all doubt easily. Everything else is more suited for the church.
"one could"... "one would"... "maybe".. is that tech-talk?
sry, in my opinion, thats youtube-comment level.
Re: large coil gun
hen918, Tue Mar 03 2015, 05:46PM
Would and could are used because it hasn't been done yet, not because the "tech" is dubious.
If something is wrong, please try to correct it. If you just think the whole concept isn't feasible, say so, and leave it at that. Please.
hen918, Tue Mar 03 2015, 05:46PM
DerAlbi wrote ...
...
"one could"... "one would"... "maybe".. is that tech-talk?
sry, in my opinion, thats youtube-comment level.
...
"one could"... "one would"... "maybe".. is that tech-talk?
sry, in my opinion, thats youtube-comment level.
Would and could are used because it hasn't been done yet, not because the "tech" is dubious.
If something is wrong, please try to correct it. If you just think the whole concept isn't feasible, say so, and leave it at that. Please.
Re: large coil gun
DerAlbi, Tue Mar 03 2015, 08:09PM
DerAlbi, Tue Mar 03 2015, 08:09PM
Re: large coil gun
Shrad, Tue Mar 03 2015, 08:41PM
I was talking about a one stage pulse compression for which propagation delay would equate discharge time so that the energy and L value see inverse evolution, and stated that pulse energy with water capacitors was convenient in that they were easy to make and dielectric was self healing, dot.
I even stated that I had no experience of coilguns but that I knew some simple facts about pulse forming networks, coaxial design and so
I don't think I said that your theory is not right or that my idea doesn't have to obey theoretical rules
I think you have a really deep knowledge of your thing and you embrace some concepts that not everyone here is able to embrace here due to not knowing enough theory, but due to that you may expect too much from a place where mainly hobbyists evolute...
the thing is that you don't know the technical background of people here as most of them choose not even to mention that, as this is not the interest here to confront personal background and play that game
usually a new concept comes out of idea confrontation and free thinking, and once you have something nice in mind then you confront it to theory and challenge the idea... if you discard any thought if it doesn't match a known theory model, how do you want to find a new concept? you have to think out of the box... and if it is frustrating to you I don't think this is an appropriate community to communicate with
maybe I'm totally wrong, but I feel this place is enjoyable for such out of the box discussion, with others explaining instead of rectifying
Shrad, Tue Mar 03 2015, 08:41PM
I was talking about a one stage pulse compression for which propagation delay would equate discharge time so that the energy and L value see inverse evolution, and stated that pulse energy with water capacitors was convenient in that they were easy to make and dielectric was self healing, dot.
I even stated that I had no experience of coilguns but that I knew some simple facts about pulse forming networks, coaxial design and so
I don't think I said that your theory is not right or that my idea doesn't have to obey theoretical rules
I think you have a really deep knowledge of your thing and you embrace some concepts that not everyone here is able to embrace here due to not knowing enough theory, but due to that you may expect too much from a place where mainly hobbyists evolute...
the thing is that you don't know the technical background of people here as most of them choose not even to mention that, as this is not the interest here to confront personal background and play that game
usually a new concept comes out of idea confrontation and free thinking, and once you have something nice in mind then you confront it to theory and challenge the idea... if you discard any thought if it doesn't match a known theory model, how do you want to find a new concept? you have to think out of the box... and if it is frustrating to you I don't think this is an appropriate community to communicate with
maybe I'm totally wrong, but I feel this place is enjoyable for such out of the box discussion, with others explaining instead of rectifying
Re: large coil gun
DerAlbi, Tue Mar 03 2015, 10:41PM
Ok, for a fruitfull discussion out of brainstorming you have to be critical for your own idea - its new, incomplete and needs to go through evolution.
If you want to pulseform a single stage your obvuiously first need to make sure you actually can form the pulse... you should agree to this.
As Signification corrected me, the order of magnitudes the propagation delay with the 1/18th of c0 is soooooo far off the speed of a projectile that should also be obvious to you.
And if you have pulseforming knowledge you should also know that there is a practical limit to the velocity factor.. right?
So from all you actually know yourself, you can derive that the idea is questionable. Yes, its worth mentioning, but not worth protecting against agressors. That defense puts you in a weak position AND it is unfair to people like Uspring who have a similar idea and get falsely good feedback in spite of similar weaknesses.
One should at least try to get a reasonable conclusion and i really didnt see that happening with you two guys ...same idea and lack of self critisism. Thats NOT how ideas undergo evolution.
As i concluded from your statement you do actually have all the knoeledge to sumarize your idea as impractical. Yet, it didnt happen. So i am sorry to be the ass here, but someone has to hold on to reality. Violence used, if needed
I am absolutely sure that despite the tone it would be even worse to let you go on with such ideas.. let you waste time and maybe even money - AND that applies to every person who could be falsely inspired. As my picture above states, i am actually your friend here.. despite the appearance..
DerAlbi, Tue Mar 03 2015, 10:41PM
Ok, for a fruitfull discussion out of brainstorming you have to be critical for your own idea - its new, incomplete and needs to go through evolution.
If you want to pulseform a single stage your obvuiously first need to make sure you actually can form the pulse... you should agree to this.
As Signification corrected me, the order of magnitudes the propagation delay with the 1/18th of c0 is soooooo far off the speed of a projectile that should also be obvious to you.
And if you have pulseforming knowledge you should also know that there is a practical limit to the velocity factor.. right?
So from all you actually know yourself, you can derive that the idea is questionable. Yes, its worth mentioning, but not worth protecting against agressors. That defense puts you in a weak position AND it is unfair to people like Uspring who have a similar idea and get falsely good feedback in spite of similar weaknesses.
One should at least try to get a reasonable conclusion and i really didnt see that happening with you two guys ...same idea and lack of self critisism. Thats NOT how ideas undergo evolution.
As i concluded from your statement you do actually have all the knoeledge to sumarize your idea as impractical. Yet, it didnt happen. So i am sorry to be the ass here, but someone has to hold on to reality. Violence used, if needed
I am absolutely sure that despite the tone it would be even worse to let you go on with such ideas.. let you waste time and maybe even money - AND that applies to every person who could be falsely inspired. As my picture above states, i am actually your friend here.. despite the appearance..
Re: large coil gun
Signification, Tue Mar 03 2015, 10:57PM
If DerAlbi would just share his information --patiently-- I, for one, feel I could learn a lot, and believe he would find that he would benefit similarly from others. There is a lot to be learned from each other! I make this statement, based on the bits and pieces of information he passed on, but in a rather aggressive one-way manner that dead-ends. This is great stuff and, quite frankly I am very interested and would like to have much more detail in a more peaceful manner--a two-way communication format is critical--IMHO.
Signification, Tue Mar 03 2015, 10:57PM
If DerAlbi would just share his information --patiently-- I, for one, feel I could learn a lot, and believe he would find that he would benefit similarly from others. There is a lot to be learned from each other! I make this statement, based on the bits and pieces of information he passed on, but in a rather aggressive one-way manner that dead-ends. This is great stuff and, quite frankly I am very interested and would like to have much more detail in a more peaceful manner--a two-way communication format is critical--IMHO.
Re: large coil gun
DerAlbi, Tue Mar 03 2015, 11:30PM
Hmmh. i do actually know that i am the ass here, dont worry. I am only agressive if i suspect failed self reflection or overenthousiasm.
All this "i want it big and powerfull"-stuff associated with the hype of Coil/Railguns is extremely predestined for such irrational discussion style.
But lets get to the topic
Big coil guns right? Duuude i hate this headline allready but let me report my advances...
i fired 2 stages now. got 20m/s (4.7J) out of it and i am having 13.5% efficiency allready.
Whats important for ME is not those numbers, but that it actually matches the simulation PERFECTLY. I dont even use some kind of triggering.. its just based on timing derived from my simulation using my efficiency optimization algorithm.
It allmost takes the fun out of it. If you know what the outcome is... booring
But i think i will make a living out of it.
I can provide a 80cm long rifle, 6kg weight (yeah heavy), 3 shots per second, 100J kinetic energy (100m/s). This thing could actually sell. Price would be about 1700$ or 1400€. So just to say: i am sorry if i cant disclose all the important bits an pieces, but if i spend 150k for prototyping i dont want any competition in the first year Not if i have spent 1 year for research financed by spare student money. (3k€ allready)
DerAlbi, Tue Mar 03 2015, 11:30PM
Hmmh. i do actually know that i am the ass here, dont worry. I am only agressive if i suspect failed self reflection or overenthousiasm.
All this "i want it big and powerfull"-stuff associated with the hype of Coil/Railguns is extremely predestined for such irrational discussion style.
But lets get to the topic
Big coil guns right? Duuude i hate this headline allready
but let me report my advances...i fired 2 stages now. got 20m/s (4.7J) out of it and i am having 13.5% efficiency allready.
Whats important for ME is not those numbers, but that it actually matches the simulation PERFECTLY. I dont even use some kind of triggering.. its just based on timing derived from my simulation using my efficiency optimization algorithm.
It allmost takes the fun out of it. If you know what the outcome is... booring
But i think i will make a living out of it.
I can provide a 80cm long rifle, 6kg weight (yeah heavy
), 3 shots per second, 100J kinetic energy (100m/s). This thing could actually sell. Price would be about 1700$ or 1400€. So just to say: i am sorry if i cant disclose all the important bits an pieces, but if i spend 150k for prototyping i dont want any competition in the first year Not if i have spent 1 year for research financed by spare student money. (3k€ allready)Re: large coil gun
Signification, Tue Mar 03 2015, 11:55PM
OK, I actually suspected this for a while--perhaps because my situation is similar!
Signification, Tue Mar 03 2015, 11:55PM
OK, I actually suspected this for a while--perhaps because my situation is similar!
Re: large coil gun
Shrad, Wed Mar 04 2015, 07:45AM
I'll leave the conversation for you guys to pursue on coil guns as you have a quite dense background already and my idea is a bit off-topic
DerAlbi, please don't see any offense but I don't think I'm overenthusiastic or overconfident in my ideas ;)
the idea in my one capacitor and one inductor being coaxial was not meant for propagating a pulse along the inductor but to maximize energy transfer and keep things simple
I'll pursue in another thread
Shrad, Wed Mar 04 2015, 07:45AM
I'll leave the conversation for you guys to pursue on coil guns as you have a quite dense background already and my idea is a bit off-topic
DerAlbi, please don't see any offense but I don't think I'm overenthusiastic or overconfident in my ideas ;)
the idea in my one capacitor and one inductor being coaxial was not meant for propagating a pulse along the inductor but to maximize energy transfer and keep things simple
I'll pursue in another thread
Print this page