Combustion powered weapon

[Daniel Vernall]

Hi there I'm looking into powering my main weapon. I can see in the rules that at certain events IC engines are allowed (a few house robots have them) but I can't see any info on combustion powered weapons.

Working just like a two-stroke engine, a cylinder with a piston and a sparkplug with the resulting linear motion directed into a weapon system with a motor to compress the air fuel mix for the next fire.

Seems no more dangerous then pressurised tanks and pneumatic weapon systems.

It would of course follow the routed fuel lines and fuel tank rules

Anyone got any info?

[maddox10]

Good one. In theory it's straigthforward. A squirt of fuel in a piston, BOOM. More and hotter gas than from a bottle. With a modern fuel injector, a pump and a fan to aid the mixing it's just a bit of creative thinking for the control spark.

I did think about it, in more ways than 1. I even did think about Walther Turbines and Wet Heater Torpedo's.

One straightforward problem.

Most event organisers , and more important, venue's don't allow combustion engines and such.

[Daniel Vernall]

I thought about that, what sort of percentage allow it you think? Mainly just the big ones like the robot wars hosted ones?

[maddox10]

Atm, I guess 0% of the venueholders in the UK. Maybe for open air events that the restrictions will be less heavy.

But HS&E is rather restricting over there.

[Daniel Vernall]

ah of course, hmm.. pneumatics seem to be the way to go then I think

[Eventorizon]

A machine called Pain in RW series 2 did something like that with fuel an oxygen, it was all contained and fired a spike... but the dam thing never moved of the starting block so we never found out how effective it really was.

[Daniel Vernall]

I'd love if I could get authorisation for some events cuz I have the drawings all together and a shopping list ready, but held off until I got some feed back. It seems a silly to disallow combustion weapons when they're very simple to contain. I'll be using a co2 paintball tank as the cylinder, with all the pressure and exhaust gases vented at the end of the power stroke. The bottle would never store more than 150 psi. and would need barely any fuel in a tank. The 500ml limit would be ridiculously oversized for this use.

Pneumatics are far more dangerous me thinks

[Eventorizon]

Pneumatics are not flammable gasses in pressure vessels. Pneumatics don't even come close.

[Daniel Vernall]

True but lots of pneumatics operate at significantly higher pressures. The fuel is not compressed until it enters the cylinder and then only at low quantities. Bots carry around 1000 psi CO2 tanks. The fuel couldn't even get to the cylinder to be pressurised for a misfire unless power is supplied to the fuel pump and then injector. The combustion chamber will be empty of fuel until pumped in.

[Max]

I believe major damage now has a flame thrower, if your tank got slightly punctured and stared leaking fuel it would be very easy for a fire to be caused, the floor is made of wood so it could get very serious. It could even be ignited from sparks from a spinning weapon. You've also got the exhaust gases which could cause issues if there isn't good ventilation but I guess you've already got the co2 from pneumatics so not such a big issue.

[maddox10]

Simplest point. The build rules allow for it.

Event organisers, venue owners and HS&E have another idea

[Daniel Vernall]

Indeed, I'll keep my designs and try and see if any event guys allow it in future thanks guys

[RoboLibre]

A list of food for thought...

fit it with a thick walled plastic fuel tank.
encase the fuel tank in 10-20mm of silicone for impact resistance. also flame resistant.
locate the tank in a well protected part of the robot, preferably with steel armour.
if using a vapour vent on the fuel tank, use a double baffled vent with flash back retarder, in-case vented vapors ignite. you could also use an expansion chamber instead.
use armoured fuel line, or run a heavy duty fuel line through a stainless steel home shower flexihose. firmly secured along entire route.
vent exhaust fumes through a catalytic converter. xD

being a tad more serious, I do see a bit of a potential issue with flammable liquids escaping and catching fire.
but I do agree this would be an interesting avenue to explore, and that "technically" it does fall within the guidelines.
If there are robots using petrol as a fuel, then there should be no reason why it should not be allowed in a static weapon at those same events.

I'd definitely hang onto your designs, and personally, I'd build the damn thing anyway, just out of interest, haha