large coil gun / Electromagnetic Projectile Accelerators / Forums

Forums

4hv.org :: Forums :: Electromagnetic Projectile Accelerators

« Previous topic | Next topic »

large coil gun

first previous 4 5 6 7 next

Move Thread

LAN_403

Uspring

Tue Mar 03 2015, 12:05PM

Registered Member #3988 Joined: Thu Jul 07 2011, 03:25PM
Location:
Posts: 711

L/R = 1..3ms

That 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.

Signification

Tue Mar 03 2015, 01:03PM

Registered Member #54278 Joined: Sat Jan 17 2015, 04:42AM
Location: Amite, La.
Posts: 367

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?

Shrad

Tue Mar 03 2015, 03:38PM

Registered Member #3215 Joined: Sun Sept 19 2010, 08:42PM
Location:
Posts: 780

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

DerAlbi

Tue Mar 03 2015, 04:55PM

Registered Member #2906 Joined: Sun Jun 06 2010, 02:20AM
Location: Dresden, Germany
Posts: 727

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.

hen918

Tue Mar 03 2015, 05:46PM

Registered Member #11591 Joined: Wed Mar 20 2013, 08:20PM
Location: UK
Posts: 556

DerAlbi wrote ...

...
"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.

DerAlbi

Tue Mar 03 2015, 08:09PM

Registered Member #2906 Joined: Sun Jun 06 2010, 02:20AM
Location: Dresden, Germany
Posts: 727

Shrad

Tue Mar 03 2015, 08:41PM

Registered Member #3215 Joined: Sun Sept 19 2010, 08:42PM
Location:
Posts: 780

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

DerAlbi

Tue Mar 03 2015, 10:41PM

Registered Member #2906 Joined: Sun Jun 06 2010, 02:20AM
Location: Dresden, Germany
Posts: 727

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..

Signification

Tue Mar 03 2015, 10:57PM

Registered Member #54278 Joined: Sat Jan 17 2015, 04:42AM
Location: Amite, La.
Posts: 367

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.

DerAlbi

Tue Mar 03 2015, 11:30PM

Registered Member #2906 Joined: Sun Jun 06 2010, 02:20AM
Location: Dresden, Germany
Posts: 727

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 1400â‚¬. 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. (3kâ‚¬ allready)

first previous 4 5 6 7 next

Moderator(s): Chris Russell, Noelle, Alex, Tesladownunder, Dave Marshall, Dave Billington, Bjørn, Steve Conner, Wolfram, Kizmo, Mads Barnkob