Hi
Anyone ever try to launch using a magnetic coil gun in place of an engine?
The design covers use of a electromagnet, driven by a charged bank of large
capictors, charged using batteries. the rocket would be fitted with aluminum
rings which are shoved by the magnetic field.
formatting link
If this could work the recovery deployment could be by way of altimiter.
That is if it were heavy or tumble if not.
any thought as to the rules that may govern such a model
Misha
VE9MTB
TRA L-1
The projectile would be the problem. The article states that the projectile
must be ferromagnetic (iron or alloy construction). There will be some
idiot in Washington that would call this a firearm or a destructive device
due to the metallic content of the vehicle. Or the fact that the technology
can be enhanced to power the vehicle to hypersonic speeds. This project is
called a number of things including "Mass Driver, Gauss Rifle, Rail Gun".
The magnetic trains in Japan work on a similar principle. They had to limit
the train speed to 200 mph, it can go much faster.
Hmmm.... there aren't any goveernment regulations
that cover such a thing as far as I know... similar
things (as far as recovery) have been done with
boosted-darts: there was a writeup on ROL that I saw
a while back... the unpowered "upper stage" was a PML
"Cirrus Dart" with an extra nosecone (modified to engage
alignment features on the booster) on the rear; recovery
used electric ejection by way of a conventional HPR
altimeter. (I forget whether dual deployment was used.)
The coilgun idea sounds interesting... acceleration
forces might be abit extreme to achieve practical
rocket performance, though...
-dave w
Hobby electromagnetic ballistics?
Does 'rocket' not entail the propulsion device being contained within the
vehicle? I can't see having the coil and supply on the rocket being a good
idea (too heavy).
This is an argument against gravity wells, not mass drivers.
Also read the book "The Moon is a Harsh Mistress". They use gravity
well weapons there too.
"How are we going to fight?"
"We're going to throw rocks."
"No, seriously."
"Yes, seriously."
It's on topic too. They launch ore-filled rockets at earth, and
purposely lawn dart them from orbit. Terminal velocity impact at that
speed resembles a nuke blast, but without the nasty radiation.
Not aluminum rings. Iron or similar alloy. Must be susceptible to magnetic
pull/push, which aluminum is not. Heavier metals... ferrous metals, I
believe.
With current technology, the weight involved and the energy requirements
would make it extremely impractical; you'd need an 18 wheeler to haul the
launch equipment large enough to launch anything larger than 6 inches tall.
The videos on the site show a device that is 4 or more times heavier, but
not much more powerful than, a B-B gun. I am sure others have come up with
more compact and powerful variations, though, so I would not rule it out in
the not-too-distant future.
~ Duane Phillips.
Forget it. If you scale it up enough to be useful, someone will decide
it's dangerous or could be used as a weapon. (Weapon: something that if
pressed against someone's face and activated, might cause them to be
hurt).
Then they'll re-interpret an existing category to cover it ("Uh, it
shoots something, so it must be a gun." or "Uh, you could put a needle
on the end and inject someone with AIDS with that, so it must be a
hypodermic!")
Either way, you won't be allowed to have it, no legislation required.
Aluminum rings *will* be repelled by an alternating magnetic field.
Lenz's Law states:
An induced electromagnetic force generates a current that induces a
counter magnetic field that opposes the magnetic field generating the
current.
So, think of the aluminum ring as a one-turn secondary coil on a
transformer. The coil is shorted, so maximum induced current will
flow, resulting in maximum magnetic field generated. The induced
magnetic field will directly oppose the magnetic field that induced
it, and the ring will be repelled.
I did a demonstration of this for a science fair project in grade
school, and won 1st prize. I used a short piece (1.5" long, .75"
diameter) of aluminum pipe, rather than a ring, to allow me to more
easily constrain its motion to one axis. It was a loose sliding fit
over the plastic tube that covered the square steel core. The
electromagnet was hand-wound from several thousand turns of "bell
wire" (bare copper with a varnish coating for insulation), and
connected to a 110 VAC line cord, with a momentary contact push
button. When the button was pushed, it would throw the aluminum tube
about 2 feet straight up in the air off of the 4" long plastic-encased
steel core sticking out the top of the electromagnet.
Bottom line: all that was required was that the "ring" conduct
electricity. Copper wire loops taped to cardboard tubes worked just
fine, as well, but the aluminum tube made for the best "display".
For some reason, I had a knack for winning science fairs in grade
school with projects that threw things in the air, blew up, etc. I
wonder if I could get away with any of them in today's litigious "zero
tolerance" world....
- Rick "Dust Explosion" Dickinson
Eddie currents will be generated in *any* conductive material in the
presence of a changing magnetic field. There are plenty of practical
examples of this at science 'museums' such as Questacon here in Canberra,
Australia.
BTW a rail 'gun' is able to 'fire' a projectile which definitely *would*
class it as a firearm in Australia. In the end it is the result that
counts, not how you achieve it.
Cheers
Bob Stephenson
bstephenatnetspeeddotcomdotau
I was not aware the FF rules on firearms and destructive devices in the gun
control act covered metallic content of rockets.
they are a destructive device only if equipped with a warhead thhat I can
find in my green book
They don't.
The only regulatory "intersect" I can think of might involve the applicability
of the FAA "model rocket" or "large model rocket" categories, which may among
other things (IIRC) call for lightweight nonmetallic construction... but then,
it's not clear that the device would constitute a "rocket" in the first place,
since it is not propelled by expelling gas produced within it.
What _are_ the FAA rules, if any, for unpowered ballistic
projectiles? (Do the "pumpkin throwers" apply for waivers
or anything?) Legally, an unpowered coilgun-launched dart
should be treated comparably!
-dave w
GREAT , we can have those. thank the lord and the second amendment.
so if it's a gun, bring em on !
those are handed out free on many streets by good will groups to prevent the
spread of aids of all things.
I now really confused.
PolyTech Forum website is not affiliated with any of the manufacturers or service providers discussed here.
All logos and trade names are the property of their respective owners.