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As first preparation for a Technic MOC of the famous Fokker Dr. I, I tried to make the most compact 8-cylinder radial engine (I know, it should be 9-cylinders...)

See attached the solution I came up with, but with this size the model would still be 100 studs long/wide and this a bit too big to my liking after the huge Cadillac.

If anybody has a solution for a working 8-cylinder that is smaller then this, please let me know.

This one does howvever work quite nice also at high speeds (~1500 RPM)

Instructions can be found on rebrickable: http://www.rebrickab...aircraft-engine

800x600.jpg

800x600.jpg

Edited by martijnnab

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First of all it's great to see another planebuilder on the scene :thumbup:

As for the radial engine, that is a tough one. I can think of two ways to make it smaller:

1) Make two cirkels of 4 cilinderheads. Put them after each other with a rotation offset such that the holes of the front row align to holes in the backrow.

2) Try to make cilinders of axles instead of the standard cilinder pieces. Some small V8 engines were shown in this forum a few weeks ago. The problem is of course that these motors are all pushrods and you need something that can pull as well...

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I hate to put a rod in your spokes but the Folker DR1 had a rotary engine. The crank shaft was fixed to the air frame and the cylinders , along with the prop which was attached to them, rotated. A good indicator of a rotary engines is the cutaway of the lower cowl for cooling. Your model looks great and if you modify it to a rotary will be very impressive. I'm look forward to seeing the rest of the model.

Edited by Karle

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Nice to see another plane builder here! Great radial, and I don't think you can get much smaller than that, unless you ditch the cylinder blocks.

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It looks great and the high revs don't seem to affect it, which is a big bonus. I thought of joining the cylinder blocks with a flex axle through the transverse holes, but after doing a quick test here I don't think the result would be any smaller, and it would certainly be much weaker.

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I hate to put a rod in your spokes but the Folker DR1 had a rotary engine.

Thanks, hadn't noticed that yet. Would be even more impressive to get working, so I started adapting it to rotary. I think it can be done with this setup, so I will post it if it works out OK.

Edited by martijnnab

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Here is the upgrade to a rotary variation. Wasn't that hard actually, but requires a reverse of parts that are fixed versus rotating. By adding a turntable and driving that, it can be done.

800x600.jpg

800x600.jpg

I made a small movie of it (not yet on youtube) where you can see how it works out then. Actually looks less impressive as you cant see the actual cylinder movement anymore (although it is there...)

http://www.bricksafe.com/files/mfjnab/8-cylinder-radial-aircraft-engine/8-cylinder%20rotary%20aircraft%20engine.mp4

Edited by martijnnab

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Cool engine. From the video it looks like the prop centerline is orbiting a bit. I suppose you technically need a balance weight for dynamic balance.

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Good idea. First I will finetune the rotary version as I think it can be made much compacter (less deep, from 5 to 3 or Max 4 studs, . After that balancing would be the next step..

Edited by martijnnab

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