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A working model of a electromagnetic mass accelerator of high power

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DerAlbi

Thu Dec 06 2018, 08:36AM

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

It would still be amazing if it worked as promised. I believed the values you claim to be possible.
Make 10m shots. Accurate 10m distance is mandatory.

Sulaiman

Thu Dec 06 2018, 10:10AM

Registered Member #162 Joined: Mon Feb 13 2006, 10:25AM
Location: United Kingdom
Posts: 3140

I have not looked at this particular mass accelerator
but I do remember from small experiments that I did several years ago that
coil-gun efficiency increases with mass.
i.e. coilguns are better suited to artillery than to bullets.
I have a small suburban garden which is my main excuse for not continuing with projectile accelerators,
but if we consider a multi-stage coilgun as a linear motor,
I see no fundamental theoretical reason why good efficiency can not be acheived.

Carrying around enough stored electrical energy for multiple shots will never (with current storage devices) compete with chemical energy of propellants,
so publishing designs for an improved coil-gun only helps the ignorant to hurt themselves or others, with no real gain in knowledge.
But it is fun and a challenge, so go for it if you wish.

DerAlbi

Thu Dec 06 2018, 11:36AM

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

so publishing designs for an improved coil-gun only helps the ignorant to hurt themselves or others, with no real gain in knowledge.
But it is fun and a challenge, so go for it if you wish.

can you explain that? (i dnot know if i understand it correctly)

V2006

Sun Dec 09 2018, 09:56PM

Registered Member #61550 Joined: Thu Apr 06 2017, 03:23PM
Location:
Posts: 86

fur DerAlbi:
VID 20181209 020737

Ich bin ein musikant
Ich bin fur das Fatherland

10 Meter
Deutsche Bruder, bitte gib mir Brot

New! Playlistl 10 Meter:

DerAlbi

Sun Dec 09 2018, 11:51PM

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

288ms for 10m. That is 38.6m/s.
With 380g that is 284J .
With 450g that is 336J.

My simulation said the energy transfer would be 235J. Not bad.

Consistent with the other video that i analyzed. It was indeed 10m! Sry for the doubt.
Still.. factor 8 away from the claimed performance.

[Edit: had typo in my calculator; I was 3m/s off because i fucked up the speed of sound)]

V2006

Mon Dec 10 2018, 09:43AM

Registered Member #61550 Joined: Thu Apr 06 2017, 03:23PM
Location:
Posts: 86

mv = MV

m = 40 gramm = 4 x 10-2 kg

v = 600 m/s

mv = 24 kg x m/s (Recoil impulse of a powerful hunting shotgun)

M = 385 gramm = 0.385 kg (The mass of the projectile electromagnetic accelerator mass)

V = mv/M = 24/0.385 = 62.33 m/s (The minimum speed of the projectile electromagnetic accelerator mass)

Recoil pulse of an electromagnetic accelerator of mass greater than 24 kg x m/s
Its weight is 49.5 kg. And the momentum of his recoil shifts him from his place by 5 or more centimeters.

Simulations give understated numbers.
Send the device to measure the speed.

DerAlbi

Mon Dec 10 2018, 11:07AM

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

You already have the measurement device: your microphone is a good enough to give an estimate.
Formula is:

v = Distance / ( Time - Distance/340)

How can you argue with impulse? You cant measure impulse by "5cm jump". Bolt it down. Then you have no impulse suddenly. What then?
The only way to argue with impulse is to put the device on frictionless rails. Then you can measure velocity. in m*v, there is no "distance".

V2006

Mon Dec 10 2018, 11:50AM

Registered Member #61550 Joined: Thu Apr 06 2017, 03:23PM
Location:
Posts: 86

DerAlbi "My gun at 40m/s and 20J has the same kickback as a 9mm gun when shooting because Impulse = ProjMass*Velocity is nearly equal"
- Does your shell weigh more than 40 grams?

9mm gun - for example, a bullet weight of 6 grams and a speed of at least 330 meters per second
this is already an impulse of 1.980 kg m / s (mv)
so that you would have the same impulse at 40 meters per second you should have a projectile mass of 49.5 grams
and you wrote about the projectile with a diameter of 8 millimeters long 30 millimeters

Can not be screwed. In the case of fixing deteriorate performance.

The sound is composite. First, the sound of launching the projectile. Then a quiet sound from punching the door. Then a louder sound from punching a steel sheet outside the door. And a very loud sound about falling steel sheet outside the door.

Count this coil:
145 mm length
Outer diameter of 23 millimeters
18 mm inside diameter
Copper rectangular wire of 3 millimeters by 4 millimeters
Electric resistance 0.02 ohm
Projectile diameter 17 millimeters
Projectile length 145 mm
450 volt capacitors 54000 microfarad
What speed will you get?
The rate of acceleration of the projectile such coil was measured by me
by measuring the time between the correct launch of the projectile and the fall of the projectile to the ground
The launch was done upright
The value of speed was in this case 40 meters per second
Impulse returns from my new coils many times more. And their impact on various materials is many times greater.

Sulaiman

Mon Dec 10 2018, 01:15PM

Registered Member #162 Joined: Mon Feb 13 2006, 10:25AM
Location: United Kingdom
Posts: 3140

With a little ingenuity,
a stick (or some string),
a can of soil (or a lump of clay)
and a ruler
you can make a reasonable estimate of velocity and energy.

The inaccuracy of speed of sound based measurements due to altitude and local climate can be eliminated if you measure the speed of sound also.
Or estimate your local speed of sound based on your altitude and weather.
It is rarely 343 m/s.
(I use 333 m/s because it is close and convenient for mental arithmrtic)

DerAlbi

Mon Dec 10 2018, 01:29PM

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

Regarding the impulse: you are right, i was calculating with a bigger design (with 100m/s) - since that is where my gun would stop being practical (for potability).

Your gun weighs 50kg. My gun weighs 1.6kg (including battery, capacitor charger and case and a full 6 round magazine). You invest >31x more material, but you only get ~14x more energy out of it.

I am not sure why you keep comparing. Your gun is bigger and therefore stronger - maybe the strongest in the hobbyist space. But i am a factor 2 ahead in material utilization - this is what actually counts. You have no idea how hard it is to improve the technology by a factor of 2. Yet you keep laughing at me how i spent my money. (neglecting my shot frequency, and magazine, and battery management)
Your goal was strength by all means - you succeeded, fine.

I am done working for you; there is no point supporting you further. You do not value math or engineering and call anyone stupid who does not agree with you. You have fundamental flaws in your design and in your approach to engineering, education and society. I cut you some slack due to communication problems.
Now you are lecturing me, how to read audio waveforms while you arent even capable of viewing one. Your shot is very visible in the audio track and you find perfect peaks. I was already measuring in your favor of you. The forum software is broken so i cant show screenshot. Maybe someone else downloads the audio from your video and analyzes it in Audacity and can confirm the 288ms time of flight

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