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5 Cylinder Rotary Air Engine

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Nigel (egi)15/09/2018 21:14:36
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22 forum posts
7 photos

Not sure where to post this as this is a rotary compressed air/steam engine designed to drive a propeller. 9mm bore and stroke and all designed by me, sadly I only have one rough sketch to go by. There are a few more details on my gallery pages and I do keep wondering if I should create some plans, just not sure how much interest there would be.

Nigel (egi)15/09/2018 21:16:26
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22 forum posts
7 photos

5cyl-005.jpg

The image doesn't give away the size of this engine and so thought this image might help.

Wout Moerman15/09/2018 21:23:01
46 forum posts
2 photos

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?

Wout Moerman15/09/2018 21:24:47
46 forum posts
2 photos

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

Nigel (egi)15/09/2018 21:26:52
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22 forum posts
7 photos

Yes, the air goes in through the crank, which is stationary, this then comes out through the side of the crank and so is timed into each copper pipe that takes the air to the cylinder head. The piston is pushed down and at the bottom of the stroke there are holes in the side of the cylinder to let the air out.

Nigel (egi)15/09/2018 21:35:11
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22 forum posts
7 photos
Posted by Wout Moerman on 15/09/2018 21:24:47:

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

It took quite a long time to build and must admit that I probably won't build a compressed air tank or flash boiler.

Although it would look good in a Sopwith Camel or similar aeroplane.

Maybe some plans so that someone else can go the hole way with the build

Nigel (egi)15/09/2018 21:36:37
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22 forum posts
7 photos

The piston and master corned with a 2mm drill acting as the gudgeon pin

5cyl-018.jpg

Steve Crow02/10/2018 16:26:40
151 forum posts
32 photos

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

Jordanbelfort23/01/2019 08:47:15
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1 forum posts

Nice and very informative post...

Howi23/01/2019 09:20:21
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257 forum posts
15 photos

+1 for plans please

Howard Lewis23/01/2019 12:27:28
2341 forum posts
2 photos

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

Howard

J BENNETT 123/01/2019 15:08:40
36 forum posts

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?

Nigel (egi)23/01/2019 20:49:19
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22 forum posts
7 photos

Not sure really why this configuration, but I sketched a rough idea and started by making the crankcase that is shown in the video **LINK**

The crankshaft is fixed and the air enters the end, comes out halfway down and enters one of the copper tubes - the tube will be the one connected to the piston that is at Tec

Nigel (egi)23/01/2019 20:52:44
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22 forum posts
7 photos

I've not measured the power or air consumption and not pushed it too far - it runs and has become a showpiece sadly

daveb23/01/2019 22:14:16
609 forum posts
10 photos

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.

Nigel (egi)23/01/2019 22:20:38
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22 forum posts
7 photos

It would be nice to build a sopwith as an indoor free-flight model. The air tanks used for paintball might be a way forward

Ian S C24/01/2019 09:52:43
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7447 forum posts
230 photos

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

Ian S C

SillyOldDuffer24/01/2019 10:12:25
4714 forum posts
1010 photos
Posted by daveb on 23/01/2019 22:14:16:

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.

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

Nigel (egi)26/01/2019 20:30:44
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22 forum posts
7 photos
Posted by Howi on 23/01/2019 09:20:21:

+1 for plans please

I only have a rough sketch and no cae ability, sorry

Edited By Nigel (egi) on 26/01/2019 20:33:18

Ian S C27/01/2019 11:07:53
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7447 forum posts
230 photos

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

Ian S C

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