i doubt it would last longer- for low explosives, which essentially this is, confinement causes faster burning. it would be aim-able, however.

@ spudblaster: that is why you use a sugar thermometer, or other high-temperature (up to about 400C) thermometer when melting. i assumed this part was in ...

i'd strongly advise heating the sugar to temperature, taking it off the heat, then stirring in the KNO3; it's much safer. there have been several accidents where people have been heating the KNO3 with the sugar and it burning them/their house/garage/driveway.

bear in mind that anything much over 5 ...

yes, if multiple loops exist- you're talking about wiring the resistor the wrong way. if you place an 18ohm resistor in series with a 9v battery, you'll get a current of 0.5 amps. if you wire another 18 ohm resistor in parallel with that- acting as a load in your scenario- the total resistance would ...

1. the first part at least simply isn't true. go back over the applications of kirchoff's voltage law again. if the resistor is wired in series with the load, the current will drop- never the voltage- according to ohm's law. if the resistor is wired in parallel to the load, you create a potential ...

V(coil 1) _ A(coil 2) _ No. turns (coil 1)
V(coil 2) -- A(coil 1) -- No. turns (coil 2)

if the maximum flow from the PP3 is 1A, and you're trying to step the voltage up to say 5000v. theoretically you could just use 9 turns on the primary and 5000 turns on the secondary, but this is unlikely to ...

800psi through a pressure washer? sounds dangerous to me. or is it regulated to something the valve can take?

either way, what you're essentially trying to do is use a blowgun valve as a primary valve. i think it's it's releasing the CO2 far too slowly- you probably need a regulator, say 80-120 psi ...

Notice the part where it says- and i quote:

Although "recreational" potato guns are not currently subject to the GCA or the NFA, they may still be regulated under state law or local ordnances. We suggest that you contact your local law enforcement agencies for additional information.

(page 2 ...

perpendicular, or normal, means at right angles to the surface- that is, sticking straight out of the surface, and all angles between the normal line and the surface are 90 degrees. for further reading on this, look quickly at refraction through blocks in optics- there is always a normal line drawn ...

Just that lot required visiting five different shops where I was given anything from 0 to 28 camera shells. I'll probably try the unhelpful ones again when different staff are in :)

which photo shops did you go to? i went to a click 1hr place, and they yold me that they have to send the cases ...

personally i'd make it a dual-chamber over/under with a 2" porting piston valve. the dual chamber partly for aesthetics, partly for manageability.

basically something like the mega-launcher, but single valved. that's probably going to be the simplest solution in the long run; all you have to do is ...

i'd sell him your old one anyway, and use what you learnt in the construction of that to build a better one second time around. it'll teach him to get other people to do his work for him rather than putting a bit of effort into learning how to do it himself.

either pipe diameter will work equally ...

http://www.kiowa.co.uk/Products/Pipe_Fittings
The main supplier of pipe to UK spudgunners, it seems (those who know about it, anyway).

http://www.koicarp.net/pvc_plumbing/pvc.html
another supplier, i just can't spot where it tells you which class they are- it just says pressure pipe.

http://www ...

It's HHO and not HHOO because the ratio between them is 2:1. This means that when it's converted back into water, there's nothing left over.

Separating them out is a good idea, they are pretty good at the facial explosion thing. Pressurised 100% hydrogen sounds dangerous, but it's almost ...

if you're worried about the schrader, take out the core and use a check valve instead. i intend to on my next project (first pneumatic, similar to copperhead prime), it's best to be on the safe side. remember with a piston, if the fill valve goes, it could fire the cannon- depending on how well your ...

V=dx/dt only gives the average velocity, not incredibly helpful if you want muzzle velocity. that said, if you're using a chrono near the barrel rather than entire flight time, it shouldn't be a problem.

pizlo, do you mean the equations of motion; V^2=U^2+2as, etc? i can't see it being difficult to ...