## Re: Coil Gun Recoil??? -- ANSWER!

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• If the magnetic coil is applying any force to the projectile, then the projectile is applying the same force to the coil. Another explanation for recoil can
Message 1 of 17 , Oct 2, 2008
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If the magnetic coil is applying any force to the projectile, then the
projectile is applying the same force to the coil. Another
explanation for recoil can be found with the law of conservation of
momentum.

Hang a both a magnet and a steel ball of equal mass at the end of two
separate strings. Without the influence of the other, each object
should hang straight down from it's string. Slowly bring the strings
closer together. As the magnet and ball come closer, they will begin
to be attracted to each other. If the magnet applied a force to the
ball but the ball did not apply an equal and opposite force on the
magnet, the magnet would continue to hang straight up and down while
the steel ball would be visibly pulled towards the magnet. This is
not the case that I would expect to see, however. I would normally
expect both the ball and the magnet to visibly move towards each
other, suggesting that each is applying the same force on the other in
opposite directions.

Most home-made coil guns shoot steel BBs. Steel is not, by itself,
magnetic. An electromagnet can only attract steel, it cannot repel
it. Coil guns designed for such projectiles are most efficient if the
projectile is pulled towards the coil until it reaches the coil. If
the coil is still energized after the projectile passes, the coil will
pull the projectile backwards and slow it down. Multiple coils can be
staged together so that another coil starts pulling the projectile
when it passes the first coil. If the projectile is magnetic, it is
possible for the coil to pull as well as push the projectile after it
passes the coil.

Momentum is mass times velocity (mass is a magnitude, velocity is a
vector: both a magnitude and a direction). The total momentum of a
system will not change. If you have a little BB sitting still inside
a larger coil gun, you have a total momentum of zero. If you send the
tiny BB in high speed in one direction, you must send the larger coil
gun in the opposite direction at a lesser speed so that the two cancel
each other out.

Rockets and jets can be explained by conservation of momentum. In
order to make the rocket move forward, you need to send burning gasses
at high speed in the other direction. A G.I. aiming a bazooka at a
Panzer tank does not need to worry about recoil because the bazooka is
just a hollow tube with a rocket inside. The hot gasses are allowed
to freely expand out the back of the tube, so the only thing I would
expect the G.I. to feel, asides from relief when he takes out his
target, is the tube getting pulled away from him from the friction of
the rocket leaving the tube.

Eric

--- In Sci-Fi_Armor@yahoogroups.com, Grauwolf <grauwulf@...> wrote:
>
>
>
>
> Greetings Carl, Gunner and All,
>
>
>
> Yeah, --- would ya believe that I'm
> still not 100% convinced??? --LOL
>
>
>
>
> A lot has to do with the switch
> activation timing of the coils themselves. If the coils are On at the
> point where the projectile is leaving the field and thus PUSHING the
> projectile --- then, sure, you will most definitely produce recoil
> equal to any other type of gun. You would have to.
>
>
>
> However, if the field is On before the
> projectile reaches it and off at center contact point --- then you
> are using the magnet to DRAW the projectile to you and not push it.
> --- In that case I am still not fully convinced that the recoil would
> be nearly the same as for the other.
>
>
>
> I'm just going to have to keep Hunting
> on that one.
>
>
>
> As to Waste Heat --- This is the only
> article that I have found that considers it a problem in Coil Guns.
> In Rail Guns (which again are different critters) Heat and Stress are
> major concerns
> do to the extreme levels of power in
> use.
>
>
>
>
> There was one other point that I found
> interesting to note. --- No Rifling of the barrel is possible or
> practical. Thus impaired accuracy.
>
>
>
>
> I was wondering if the use of veins,
> fins, or even carved grooves on the projectile itself would be enough
> to counter this shortcoming in Coil Guns. For Rail Guns the
> velocities are so high that other than for extreme long ranges
and/or guided munitions I do not
> think the lack of rifling would be very much of an issue.
>
>
>
> What do You All think???
>
>
>
>
>
>
>
>
>
> Keep It FUN!
>
>
>
> Dan G
>
>
> SCI-FI
> ARMOR
> --- Because the Multiverse is NOT
> a friendly place.
> http://groups.
> yahoo.com/ group/Sci- Fi_Armor/
>
• Greetings Eric and All, THANKS! For that great and fairly thorough explanation. --- Well, ~ DUH! ~ “coils pushing the projectile” I don t know where my
Message 2 of 17 , Oct 4, 2008
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 _filtered #ygrps-yiv-1704695455 {margin:0.79in;} #ygrps-yiv-1704695455 P {margin-bottom:0.08in;}Greetings Eric and All,THANKS! For that great and fairly thorough explanation. --- Well, ~ DUH! ~ “coils pushing the projectile” I don't know where my brain was. Can I blame it on the pain meds??? Yeah, I didn't think so. --LOLJust one other point since I have your attention if you would be so kind???From what I understand to a certain point a Coil Gun can use darn near an unlimited number of coils in series. Thus allowing each to provide only a small amount of actual energy to move the projectile further down the barrel at ever increasing speeds. Since the force applied by each coil is so relatively small and working only to increase the the momentum of the moving object wouldn't the force of the recoil itself still be only as great as that applied by the individual coil???? --- Or is that force somehow accumulative???I REALLY DO appreciate Everybody's efforts in helping me to sort this all out!!!!THANKS ALL!!!Keep It FUN!Dan GSCI-FI ARMOR--- Because the Multiverse is NOT a friendly place.http://groups. yahoo.com/ group/Sci- Fi_Armor/

• I ve been a bit busy with school recently, but I ve given this some thought on how to explain it. With a single coil, it is held securely to the gun so you
Message 3 of 17 , Oct 8, 2008
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I've been a bit busy with school recently, but I've given this some
thought on how to explain it. With a single coil, it is held securely
to the gun so you can aim the gun, right? When the coil energizes and
pulls the projectile forward, any force applied or change in momentum
is transferred from the coil to the gun and then to your hand (which
is why you feel the recoil). If you have multiple coils, they all get
added together so that, if the projectile is accelerated the same
amount as earlier, the same total amount of force or momentum is
applied. That total is transferred from the multiple coils to the
single gun frame holding them all together, and then to your hand, so
you would feel the same amount of recoil. Multiple coils are more
energy efficient, but they will produce the same amount of recoil as a
gun with a single coil.

Eric

--- In Sci-Fi_Armor@yahoogroups.com, Grauwolf <grauwulf@...> wrote:
>
>
>
>
> Greetings Eric and All,
>
>
>
> THANKS! For that great and fairly
> thorough explanation. --- Well, ~ DUH! ~ "coils pushing the
> projectile" I don't know where my brain was. Can I blame it on the
> pain meds??? Yeah, I didn't think so. --LOL
>
>
> Just one other point since I have your
> attention if you would be so kind???
>
>
>
> From what I understand to a certain point a Coil Gun can
> use darn near an unlimited number of coils in series. Thus allowing
> each to provide only a small amount of actual energy to move the
> projectile further down the barrel at ever increasing speeds. Since
> the force applied by each coil is so relatively small and working
> only to increase the the momentum of the moving object wouldn't the
> force of the recoil itself still be only as great as that applied by
> the individual coil???? --- Or is that force somehow accumulative???
>
>
>
> I REALLY DO appreciate Everybody's
> efforts in helping me to sort this all out!!!!
>
>
>
> THANKS ALL!!!
>
>
>
>
>
>
>
>
>
> Keep It FUN!
>
>
>
> Dan G
>
>
> SCI-FI
> ARMOR
> --- Because the Multiverse is NOT
> a friendly place.
> http://groups.
> yahoo.com/ group/Sci- Fi_Armor/
>
• Greetings Eric and All, Great explanation! Thanks! Hows this for yet another thought? --- I was thinking about Maglev Trains the other day. Some use magnetics
Message 4 of 17 , Oct 11, 2008
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 _filtered #ygrps-yiv-1597073398 {margin:0.79in;} #ygrps-yiv-1597073398 P {margin-bottom:0.08in;}Greetings Eric and All,Great explanation! Thanks!Hows this for yet another thought? ---I was thinking about Maglev Trains the other day. Some use magnetics as the propulsion system as well as for ride suspension. Basically they do this by using the two poles of the magnets. First as opposites attract to draw the “projectile” magnet to the coil magnet. Then switching off briefly allowing it to pass. Then hitting the other pole with a similar pole charge thus pushing the projectile magnet down range to the next attracting coil.Do you think that such a system employed in a Coil Gun would add to its performance??? --- I was wondering if the Double Kick wouldn't reduce the number of required coils to achieve a given muzzle velocity but still allow you to use a lower voltage??? Sort of a Two-For-One shot.Thoughts???Wiki – Maglev Transporthttp://en.wikipedia.org/wiki/Maglev_trainDan GSCI-FI ARMOR--- Because the Multiverse is NOT a friendly place.http://groups. yahoo.com/ group/Sci- Fi_Armor/

• If you use a magnetic projectile that is specifically lined up, then yes it would work. If you use a ferro-magnetic material like iron or steel, the metal
Message 5 of 17 , Oct 12, 2008
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If you use a magnetic projectile that is specifically lined up, then
yes it would work. If you use a ferro-magnetic material like iron or
steel, the metal aligns itself parallel to whatever magnetic field is
nearest, and so is attracted to whatever magnetic fields are nearby.
This means that you can only pull an iron or steel projectile. You
could use rare earth magnets, but I bet it'll be a bit pricey.

Eric

PS Carl and I just got back from a boat battle today, the last one of
the year. For the fourth round today we took on the club in our
unarmed cargo vessels for more than 20 minutes before they were able
to finish us off (regular battles are 15 minutes).

--- In Sci-Fi_Armor@yahoogroups.com, Grauwolf <grauwulf@...> wrote:
>
>
>
>
> Greetings Eric and All,
>
>
>
> Great explanation! Thanks!
>
>
>
> Hows this for yet another thought? ---
>
>
>
> I was thinking about Maglev Trains the
> other day. Some use magnetics as the propulsion system as well as for
> ride suspension. Basically they do this by using the two poles of the
> magnets. First as opposites attract to draw the "projectile"
> magnet to the coil magnet. Then switching off briefly allowing it to
> pass. Then hitting the other pole with a similar pole charge thus
> pushing the projectile magnet down range to the next attracting coil.
>
>
>
> Do you think that such a system
> employed in a Coil Gun would add to its performance??? --- I was
> wondering if the Double Kick wouldn't reduce the number of required
> coils to achieve a given muzzle velocity but still allow you to use a
> lower voltage??? Sort of a Two-For-One shot.
>
>
>
> Thoughts???
>
>
>
>
>
>
> Wiki  Maglev Transport
> http://en.wikipedia.org/wiki/Maglev_train
>
>
>
>
>
>
>
> Dan G
>
>
> SCI-FI
> ARMOR
> --- Because the Multiverse is NOT
> a friendly place.
> http://groups.
> yahoo.com/ group/Sci- Fi_Armor/
>
• Greetings Eric and All, Again THANKS! Some Great points! ... There is no such thing as Cost Overruns in Sci-Fi! --LOL Hhhmmm --- Now I m thinking that
Message 6 of 17 , Oct 13, 2008
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Greetings Eric and All,

Again THANKS! Some Great points!

> You could use rare earth magnets, but I bet it'll be a bit pricey. <

There is no such thing as Cost Overruns in Sci-Fi! --LOL

Hhhmmm --- Now I'm thinking that electro-magnets within the
projectiles themselves might have advantages over those rare earth
pieces. Perhaps more as sabot type rounds???

>PS Carl and I just got back from a boat battle today, the last one of
the year. For the fourth round today we took on the club in our
unarmed cargo vessels for more than 20 minutes before they were able
to finish us off (regular battles are 15 minutes). <

GOOD JOB!!! --- There are certainly a number good stories (and movies)
out about merchant ships dueling it out with enemy subs etc. Some with
some very surprising yet TRUE results! It sounds like you are keeping
a proud Naval tradition alive! -- BRAVO ZULU!!!

Me --- We just got over our first major winter snow storm. I got to
spend the WHOLE WEEKEND cutting up and clearing away down trees and
branches around our house and our neighbors. Plus of course shoveling
tons of heavy wet snow. Not to mention all of the really FUN power
outages! --- Yeah, what a weekend of FUN! Yippee!!!! --- Grown!
Someone pass me the aspirins! --LOL

Keep It FUN!

Dan G

SCI-FI ARMOR
--- Because the Multiverse is NOT a friendly place.
http://groups.yahoo.com/ group/Sci-Fi_Armor/
• we haven t seen our first snowfall yet, and i m in no hurry for it, passes the virtual bottle of excedrin max . gunner ... From: Dan
Message 7 of 17 , Oct 13, 2008
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 we haven't seen our first snowfall yet, and i'm in no hurry for it, "passes the virtual bottle of excedrin max"."gunner" --- On Mon, 10/13/08, Dan wrote:From: Dan Subject: [Sci-Fi_Armor] Re: Coil Gun Recoil??? -- ANSWER!To: Sci-Fi_Armor@yahoogroups.comDate: Monday, October 13, 2008, 11:12 AMGreetings Eric and All,Again THANKS! Some Great points!> You could use rare earth magnets, but I bet it'll be a bit pricey. PS Carl and I just got back from a boat battle today, the last one ofthe year. For the fourth round today we took on the club in ourunarmed cargo vessels for more than 20 minutes before they were ableto finish us off (regular battles are 15 minutes).

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