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Registered Member #1906
Joined: Sat Jan 03 2009, 05:06PM
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Posts: 39
Been thinking of this for a while but I can't seem to find any clear answer: Coilguns have, as I've understood it, typical efficiencies of around 0.5-5%. What efficiencies can be expected from a railgun?
I would also be interested in some information on different railgun designs, preferably both working and not working ones :P
Registered Member #1062
Joined: Tue Oct 16 2007, 02:01AM
Location:
Posts: 1529
Rail gun efficiencies typically get larger as the guns themselves become larger. The highest efficiency on a low power rail gun (6kJ) so far has been around 19%, by university of Virginia. There are lots of different configurations, off the top of my head: Brush projectiles Series augmented parallel augmented permanent magnet augmented plasma armature solid armature hybrid armature Google all the above, and you will find some things. Your questions are way too generalised to give a thorough answer.
I have some links on that page, some links are broken now I really should clean that page up. I am in the middle of moving though so it is not going to happen right away.
Registered Member #1906
Joined: Sat Jan 03 2009, 05:06PM
Location:
Posts: 39
Thanks for the links Jasonr. I've already been on your site, didn't notice the links though. Your site offers one of the few graphical illustrations on augmented railguns available :P
I do however have a question on your illustration of a series argumented railgun: Wouldn't powering the whole outer rails counteract the acceleration of the projectile in the beginning of the rail? I don't know the Lorrentz force so please excuse me if I was wrong.
Registered Member #2317
Joined: Thu Aug 27 2009, 01:45AM
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Posts: 27
An efficiency of 32% was achieved with a relatively small-scale helical variant of a railgun. This is basically a coilgun with a coil that slides along with the projectile. Thus combining the high-efficiency capability of a railgun with the durability of a coilgun.
Here is the paper in which this experiment is explained. The paper also has some very useful equations for calculating system efficiency.
Registered Member #1906
Joined: Sat Jan 03 2009, 05:06PM
Location:
Posts: 39
Thanks for the link Jordan. I really apreciate the diagram of a helical railgun, first one i've come across. However it does seem quite similar to this:
Registered Member #2317
Joined: Thu Aug 27 2009, 01:45AM
Location:
Posts: 27
woxxey wrote ...
Thanks for the link Jordan. I really apreciate the diagram of a helical railgun, first one i've come across. However it does seem quite similar to this:
Is it, or am I misstaken?
I believe you are right. It appears to be the same concept. I guess it could be called either a helical railgun or a sliding coilgun being that it encompasses both concepts in its approach.
I'm very tempted to attempt this approach in my upcoming project rather than my current plans for a railgun. The rail erosion in railguns is a serioius problem that will require the rails to be replaced very often.
edit: I just noticed that in the paper to which you linked me, the author recognizes Engel et al. (the author of the paper to which I linked you.)
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Railgun efficiency & request for links or info.
