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quorneng
10-04-2009, 07:37 PM
A number of WW1 types used a rotary engine. In most cases it was very visible. To my mind it is very much part of a scale airframe.
Now an out runner is in effect a rotary engine and a low kV type can turn a relatively large slow prop in comparison to its diameter.
So if you buried the out runner within the crankcase of a scale rotary the whole engine installation ahead of the fire wall could be to scale as well.

I did achieve something like this quite some time ago with my small 16" electric control line Fokker Triplane although this was a conventional geared motor installation.http://www.youtube.com/watch?v=4PIV0f6TZOEThe scale Oberursel is built up from thin card.

As a start I have scaled a 9 cylinder Gnome Monosoupape so that its crankcase exactly matched the bell diameter of an Emax CF2812 out runner.
Nine very lightweight cylinders are then simple glued directly to it and the cam case, push rods and rockers added. It all made of depron and weighs just 2 gms, yes that right, 2 gms!
The 7x6 prop is just about scale diameter.
There will of course be a bit of windage losses but it should be ok for 8000 rpm although with such light components it should not be too dangerous!
We shall see!

dbcisco
10-04-2009, 07:40 PM
Very cool!

groundrushesup
10-04-2009, 08:29 PM
A number of WW1 types used a rotary engine. In most cases it was very visible. To my mind it is very much part of a scale airframe.
Now an out runner is in effect a rotary engine and a low kV type can turn a relatively large slow prop in comparison to its diameter.
So if you buried the out runner within the crankcase of a scale rotary the whole engine installation ahead of the fire wall could be to scale as well.

I did achieve something like this quite some time ago with my small 16" electric control line Fokker Triplane although this was a conventional geared motor installation.http://www.youtube.com/watch?v=4PIV0f6TZOEThe scale Oberursel is built up from thin card.

As a start I have scaled a 9 cylinder Gnome Monosoupape so that its crankcase exactly matched the bell diameter of an Emax CF2812 out runner.
Nine very lightweight cylinders are then simple glued directly to it and the cam case, push rods and rockers added. It all made of depron and weighs just 2 gms, yes that right, 2 gms!
The 7x6 prop is just about scale diameter.
There will of course be a bit of windage losses but it should be ok for 8000 rpm although with such light components it should not be too dangerous!
We shall see!


Cool idea. How's it balance?

GRU

degreen60
10-04-2009, 09:33 PM
Here is the engine I made for my morane saulnier L a couple of years ago. It is printed paper wrapped around foam cylinders. I have found that I can only see the engine rotate when flying if the bottom of the cowl is open. If the cowl is closed, even when flying toward myself I can not see the engine.

quorneng
10-16-2009, 11:37 PM
Here's a short video of the Gnome Monosoupape running up to full power on a 2s LiPo.
I will measure properly but I guess it is doing about 7000 revs and nothing comes off!
http://www.youtube.com/watch?v=SG16TlVgnPQThis is exactly the same motor, prop and battery I use on the Endurance Wing Dragon so I will measure both to see how much is actually lost by the dummy engine.
Next will be a bigger, higher scale version sized for a 10" prop.

degreen60
10-17-2009, 12:05 AM
The foam rotatory I made for my Morane Saulnier L has an 8 inch prop. It turns 5200 rpm on 2s Lipo. Just like the real engine it throws a clyinder every now and then. I think maybe a clyinder may hit the ground on some of my terrible landings.

quorneng
10-19-2009, 03:53 PM
Now if I scale a Sopwith Pup around this Monosoupape (yes a few did use it) then it comes out to just 24" span.
I would like to use a scale RAF15 wing section but this would mean the front spar is just 6mm deep and the rear only 4 so it looks like load bearing rigging wires.
The wing would be much too thin to hide the aileron servos so its scale "closed loop" control runs back to the servos (& battery) mounted just behind the firewall.
Only ideas at the moment.