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Spockie-Tech
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Joined: 31 May 2004
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yeah, now we're talking ! Laughing Donuts, Burnouts and Drag races in the shopping center carpark anyone ?
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Post Tue Aug 03, 2004 8:47 pm 
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Nick
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Yeah Arron, its been one and its called a Volvo! Laughing

(No offense, I just couldn't resist!)
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Post Tue Aug 03, 2004 8:50 pm 
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ffej
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Joined: 22 Jun 2004
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Bugger the Etec's, I want a pair of those huge Perm motors, 72HP goodness. Add a shatload of 72V NiCd packs to it and you've got a very high power to weight raito, fun fun when it comes to acceleration Very Happy
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Post Tue Aug 03, 2004 9:07 pm 
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andrew



Joined: 16 Jun 2004
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Location: Castle Hill, Sydney. N.S.W


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@Brett, I saw on a site. It was the builder of middleweight parasite (walker/shuffler driven by 3 briggs and stratton electric motors. uses 1 or 2 for a overhead spinner drive) he built the same thing using 2 ev warriors and a rubber wheel friction driving a bicycle wheel. Seemed to be effective and worked well.

@DavidM- Could u post a picture of this scooter if possible please. Thanks in advance.
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Post Tue Aug 03, 2004 10:10 pm 
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Nexus
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Lately have been also thinking of an electric bike, prob due to scooter parts becoming available.

Have an old bmx lying around and have been thinking of attaching 2 big scooter motors on it and a battery mount.
It would be a small tuff little nimble bike i figure.
Still thinking how to attach 2 motors to one wheel on a bike.
Orginal thought was 2 chains

Friction drive, maybe, never thought of using it before but minimowers success was based on the same principle so maybe needs more consideration.
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Post Tue Aug 03, 2004 10:26 pm 
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timmeh
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how fast can a wheel chiair go as im thinkin of using one motor and 3 12v 12amp hawkers at 36v for a electric go cart i want it to go pretty fast at least 40k
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Post Wed Aug 04, 2004 8:59 pm 
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Knightrous
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Well i hate to break the electric theme, but I don't think you'll find any go kart much faster then a Gas Turbine powered cart or one with a nice big "ricer" style Pulsejet on it!

Another viable option if someone could makeone that works properly, would be a Scram-jet Twisted Evil

EDIT - If anyone want to see the power of a gas turbine, check out this video! http://www.gas-turbines.com/images/squirt_2/squirt_2_at_pc_oct_2001_(short).wmv
I love the afterburner!
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Post Wed Aug 04, 2004 9:11 pm 
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Spockie-Tech
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I dont think you will get a wheel chair motor to go that fast unless you gear it way up, and then it would have very little torque for acceleration.

Most of them operate on 24v, and still turn pretty slow. Someone told me that they are legally limited to 12km/hr (probably to stop people like me from building them like I mentioned earlier).

Many of the earlier Robot Wars bots were powered by wheelchair motors, and none of them moved particularly fast.. and that was at 80Kg bot limit. by the time you built a go kart with wheelchair motors, decent batteries and then added a person, you would have to be pushing 120-150Kg all up weight I think.

Electric Go Karts sound like a good idea with motors like the Perms and E-Teks until you consider the weight of the batteries required to feed them hundreds of amps for any reasonable length of time. If our matches were longer then 5 minutes, our bots would all be running petrol engines. The energy per kilo of petrol is awesome, its only when short-term power is needed that battery powered electrics becomes an economical option.

If you dont mind riding your kart for 5 minutes then recharging it for 2 hours then its ok.
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Post Wed Aug 04, 2004 10:50 pm 
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andrew



Joined: 16 Jun 2004
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Well they sell electric motor bikes which uses a clever computer thingy built into teh bike and a etek for power. It costs about 6000 american though i think.
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Post Thu Aug 05, 2004 3:04 am 
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ffej
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IIRC, the limit placed on powered vehicles that don’t require a licence is 230W in NSW, don’t know about the other states.

Batteries really aren’t a great way of storing energy, fuel cells on the other hand have a much higher Watt Hour to Weight ratio, and a fuel cell/electric motor combo is lighter than the equivalent IC engine + fuel. They can also be refilled in about the same time as an ICE can be.

Dont know if they could be used in robotics though, even if the price came down, theres still that little detail about hydrogen being explosive . . .
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Post Thu Aug 05, 2004 5:12 pm 
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Nick
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I suspect that fuel cell cars use a catalytic converter or some other method to recombine the hydrogen into water. For robots, the traction power byproducts might go to fuel a weapon along the lines of a cordless nail gun powered by hydrogen rather than butane - it would power a wicked spike or flipper.

Come to think of it, is there any rule that says you CAN'T use the principle of a butane nail gun to drive a weapon? Butane and petrol are both liquid hydrocarbons, an ICE and a nail gun both have cyclinders, pistons and sparkplugs - in fact they are really quite similar. I don't think I want to try it myself, but the idea is interesting.
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Post Thu Aug 05, 2004 10:16 pm 
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Spockie-Tech
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Someone was talking about that on the BattleBots forum a while back. the mechanism of a butane powered nailgun is quite interesting, but the consensus seemed to be (IIRC) that a nail gun doesnt have much success at driving nails through any reasonably hard metal.

Quite a few people have tried powerful pneumatic spear bots and a fast rammer with a spike probably carries more energy with the whole mass of the robot behind it, but they rarely make more than a dint or small hole.

Untethered projectiles and fuel powered devices and explosives arent legal at most competitions anyway. pity, I'd like to think of an arena where it would be safe to open up a section of the rules to encourage some new designs. not that people arent coming up with new ones on occasion, but it would be good to inspire a whole new breed of robots. I like flame throwers myself, but good luck finding somewhere that will let us run them,.
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Post Thu Aug 05, 2004 10:26 pm 
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Nick
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Oh, I wasn't thinking so much about actually using a nail gun to shoot nails, I was thinking of using the principle to replace compressed air or CO2 to activate a pneumatic ram. in place of the nail driver blade would be a more substantial piston and rod that can be coupled to a flipper arm. I am sure there a million engineering problem to solve, its just day-dreaming...

Its a bit short-sighted of the American competitions to ban something like this as its really very similar to a single cycle of a petrol engine and the amount of fuel in a nail gun cell is quite small. I can't see it being more dangerous than Ice Wave exploding at the recent NPC event Smile
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Post Fri Aug 06, 2004 12:55 am 
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Spockie-Tech
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yes, the problem with making rules for such an inventive bunch of people though is thats its hard to predict just how far they will go with it.

Simple rules saying explosives are banned is easy to interpret. but if you then allow "internal combustion engines", someone will no doubt argue that a bullet is a form of internal combustions since the explosion is contained in the shell.. just like the cylinder of an engine.

create a weight bonus for whatever reason and while the original proponent of the bonus might be fair and use it for the mechanism they had in mind, but someone else more competitive will immediately start figuring out how to turn it to their advantage by improving their defense or offence with the additional weight.

I think the innovation levels have slowed a little bit presently, with people efforts mainly going into making "A better rammer" or "a more powerful spinner" or whatever, and while thats not a bad thing to refine the existing engineering for a while, I love to see new and unusual designs as well which only pop up occasionally.. mainly because they are hard to make work as well as the proven designs. and as I have said before, I'm planning on introducing a little bit of terrain variability over time to encourage another burst of innovation from people hopefully..

If anyone can think of any rules that could be relaxed without compromising safety significantly, I'd like to hear from you.
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Post Fri Aug 06, 2004 9:33 am 
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Nick
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Hmm, I always thought the entanglement rule was purely for TV purposes. Glue and other liquids might be going too far, But a net to comabt spinners might work out...

I would also like to see some arena traps (not active hazzards) like pits. This would even up the wedges and pushy bots VS the lifters and spinners.

While we are speculating on out-there ideas, I would like to see a disused swimming pool, roofed over with lexan and used as an arena, Standing above the bots would be a new experience and might also be safer.
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Post Fri Aug 06, 2004 11:25 am 
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