5 Cylinder Rotary Air Engine

Very nice! I am very interested in compressed air engines and would love to see a plan or sketch. The porting is I n the rear of the crankcase? Can you explain the mechanism a bit more? Just 1 opening in the stationary part?

And what kind of plane will it fly? Any idea for a airtank? Or am I getting carried away?

Edited By Wout Moerman on 15/09/2018 21:36:45

Hi Nigel, I'm very impressed with this build. I still can't get my head around the way the air intake works. Maybe you could post some more photos or a sketch to demonstrate.

I'm making a flat twin at the moment that uses a ball valve for the intake, similar to Gasparin Co2 engines.

Cheers

Steve

Nice and very informative post...

+1 for plans please

A compressed air version of the Gnome, Le Rhone,or Clerget. Excellent!

Howard

Just curious, but why did you go for a rotary engine rather than a radial. Also, have you any idea of power output and air consumption?

I recall fizzy drinks bottles being used for on board CO2 tanks. Can't remember how much pressure they would take but it was a lot. Should be easy enough to pressure test a few bottles with a boiler test set.

daveb, the ones with soft drink bottles used air pressure, the CO2 motors used the little CO2 gas cylinders.

Ian S C

Quite a few people, many of them not very bright, have pressure tested plastic bottles. The most common reason is they want them to go bang! Mostly they report attempts to measure burst pressure, and their methods aren't likely to be accurate.

The highest burst figure I've seen was about 300psi, the lowest 80psi. Mythbusters reported bursting 2L bottles at about 150psi - they're more credible source than most,but don't get everything right!

Safe working pressure is another matter. One source claims the bottles are designed for 120psi and - in normal use - the internal pressure doesn't exceed 80psi. The other issue is the number of cycles the container can safely do before weakening. As plastic bottles are disposable it's unlikely the makers rated them generously. It's also unclear over what temperature range the bottles are safe. Cold would tend to make the plastic brittle and heat would tend to soften it.

If you know what you're doing, I don't think it unreasonable for a model maker to deliberately take the risk that his plastic bottles might explode. The amount of energy stored in the bottle is low. It's not in the same league as a boiler. Although the bang is loud enough to damage hearing and flying plastic might damage eyes, I think gloves, ear-defenders and protective glasses would be sufficient protection. Provided you're not actually holding the bottle when it goes off, that is!

Liquid carbon dioxide - as stored in a Sparklets bulb - is about 900psi.

Dave

Only a rough sketch, that's often more than I have when I build on of my hot air motors.

Ian S C

Very nice, an interesting project, get it written up for ME