Request information about the sale price of a fully automated miniature submarine.

In light of this tempest of response in such a short time, I would like to pick your brains about the possible sale price of some other suggested projects:

I: A Gauss gun (for those of you who are unfamiliar with the term, a Gauss gun is a series of electromagnetic coils surrounding a tube, a magnetic projectile is placed at one end, and each of the coils is activated in sequence, causing rapid acceleration of said projectile. For those of you who do know, I apoligise for being patronising, or pedantic; it comes with the proffession.) capable of launching a projectile at anywhere between a pellet gun and a rifle, with as short a length of time between shots as possible (the capacitators need to charge) and also able to hit a target (no larger than 25 cm by 25 cm) accurately at a distance of 250 meters. II: An automated aircraft (suggested by the same girl who proposed the minisub) capable of attaining speeds of 20mph, flying at over 200 meters of elevation, carrying a small (75 gram) payload, evading detection, and flying for over three hours in favorable weather conditions.

Once again, your suggestions would be most greatfully appreciated.

Sincerely yours, -Jon Baum

Reply to
Jon Baum
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Dear Jon Baum:

... also called a rail gun.

Neither worth anything to me.

David A. Smith

Reply to
N:dlzc D:aol T:com (dlzc)

Oh no! A railgun is something entirely different! It uses a projectile that is actually a magnet, and it uses rails, not coils, hence the name. Also, the force utilised by a railgun is not magnetism, as in the Gauss gun, but rather a property thereof, the Lorentz force. Besides, where in a gauss gun, the projectile moves perdendicular to the electromagnet, in a railgun, the force runs parallel to it. Or them, as the case may be.

Sincerely yours, -Jon Baum

Reply to
Jon Baum

Dear Jon Baum:

They fire, most commonly, aluminum slugs. A changing magnetic field is used to induce eddy currents in the slug. The slug is "gripped" by these currents.

Yes, there are coils in a railgun.

Magnetism is part and parcel of a railgun.

Magnetism itself does not add energy to the motion of a slug. It is only the "Lorentz force" as you call it that can do this, just as it is in an electric motor and its rotor.

I think you are making a distinction without a difference.

David A. Smith

Reply to
N:dlzc D:aol T:com (dlzc)

Devices with greater capability are currently being funded by DARPA. To execute such a device will cost millions.

These devices are already on the market by at least two companies for tactical reconnaissance.

Why the fascination with military hardware?

Reply to
Harry Andreas

"N:dlzc D:aol T:com (dlzc)" wrote

Not so.

A Gauss gun uses a ferrous projectile with a series of electromagnet coils with their axis co-incident with the barrel axis. The coils are powered in sequence to pull the projectile down the barrel. The coils have to be actively controlled to match the power sequence to the projectile position. It's purely a magnetic force which accelerates the projectile. Think of it as a whole bunch of solenoids with the projectile being passed from one to the other.

A rail gun uses a conductive (not necessarily magnetic) projectile which rides on two rails which are parallel but offset to each side of the barrel axis. A magnetic field is set up by coils *perpendicular* to the barrel axis and the rail plane (not parallel as in a Gauss gun) and a very high voltage is introduced between the two rails. Current passes from one rail to the other through the projectile...it's the interaction of this current and magentic field (both perpendicular to the barrel axis) which accelerates the projectile down the barrel. No sequencing necessary, as the current moves with the projectile.

Tom.

Reply to
Tom Sanderson

Dear Tom Sanderson:

You (and the OP) are correct.

Pedantic point: in the frame of the projectile, there is a strong *electrostatic* force. The magnetic field is quite weak at that point. Magnetic fields cannot transfer energy... only change directions. If you find a magnet "changing speed", it is the induced/actual "electrostatic" field doing it.

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aka "coilgun"

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I had them conflated in my head. Thanks for your efforts.

Are you familiar with "linear induction motors"? They are used many places, some of which are amusement park rides. A magnetic field is set up transverse to the intended direction of motion, then the field is quenched and/or reversed. Eddy currents in the conductive aluminum plate provide resistance to the reversal, and a thrust is produced. Not railgun or gauss gun speeds but...

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David A. Smith

Reply to
N:dlzc D:aol T:com (dlzc)

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A project that started out as a glorified model airplane has flown the Atlantic autonomously. A model plane flying at a reasonable height is rather difficult to spot. Particularly if it has a half way decent muffler.

Brian Whatcott Altus OK

Reply to
Brian Whatcott

I'm still wondering about the "avoid detection" part of the spec. I can see "Avoid collision" which would be a pretty good endeavor. Actually, having a small flock of these flying around could be an interesting endeavor. They would each have to work out their relative position in the flock, balance out the needs of the flock with their needs (the lead plane must be rotated). It might teach us a little about the dynamics of mass flight and migrations.

Michael

Reply to
Herman Family

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Hmmmm... to check for 100 meter submersion capability I would be tempted to do what is done with watches. Put them in a strong container full of water, then apply 150 psi of air or preferably hand pumped water. (A converted grease gun would do nicely) That sophisticated little test might cost me - oh $15??

Isn't that how engineers usually test?

Brian Whatcott Altus OK

Reply to
Brian Whatcott

High gain dynamic pitch, roll, yaw and thrust control? In a thimble sized brain. Gotta love it.

Brian Whatcott Altus OK

Reply to
Brian Whatcott

That in a thimble size brain would be remarkable, but in addition to those more regulatory level controls, there is real time pattern recognition, navigation in 3D, and probably a few other high level processes going on. And a thimble would be a rather large brain for a bird.

Just a thought, but if birds are in a wedge, I wonder if their cognitive load is reduced, conserving energy for muscles. I know that their muscular load is reduced because of the wedge pattern, except for the lead bird. It seems that just keeping a relative position is much easier than the level of navigation they do flying around in a forest. I've noticed that they don't keep the exact relative positions, but tend to wander within the pattern a good bit. Geese also practice formations on the ground for a week or two before the big flights start. I've watched them march around the parking lot in wedge formation before they finally decide to start honking up a storm and finally take off in formation.

A flock of independent planes would be a good research project. I wonder if they'd let an old control engineer in on the project....

Michael

Reply to
Herman Family

That or get a diving suit, and take the unit down until the 100 meter watch failed.... :)

Michael

Reply to
Herman Family

A search of the faculty at -

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lists no Jon Baum. Also slightly suspicious is the yahoo.ca email address.

Reply to
paul

This bit about the practice is, to me, almost more amazing that the flight and contol with limited brain size.

jmh

Reply to
jmh

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