New stunt engine build

Brian Turner, an engine builder of considerable reputation in the F2C world, has turned his attention to building an engine for F2B (for his own use only - no intention to build any more after the first 2). I have persuaded him to keep a picture log of how he is approaching the making and even lent him my digital camera to help capture the process. I am hoping that the pictures will be good enough for me to write up the whole process for publication on the web. Here is the first installment - a couple of views of the layout drawings. Brian has prepared a set of detail drawings and will be working from them. Most of the views are too big for my old scanner but if I can get a good enough picture of them I will post all of them as well. The engine will be all machined from solid - no castings. Currently the cylinders are finished and have been sent to Russia for chroming.
If there are any questions that I can't answer Brian only lives down the road from me.

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This is the basic spec for the engine. It is based on the Stalker 61 LT LS that Brian has developed over the past couple of years. He has made significant modifications to it and it is now performing very well.

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Front view. Notice the offset venturi. This is to enable the port in the crankshaft to be in the optimum position for best balance. It does make the machining trickier.

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Interesting a rear exhaust baffled engine set up for a tuned pipe. What is the baffle height in relation to a Tigre 60. No signs of a ring appears to be lapped, what is the planned metallurgy; AAC, ABC, ceramic, plasma?

Hi Carl

No tuned pipe but a rear silencer as typical on the Russian engines.

AAC setup - no ring lapped fit piston

Here are the actual drawings. Camera pictures only as yet but I hope to get them scanned in properly soon.


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I wish I got drawings as nice as those at work.

We have a small room full of 3D CAD designers plus one guy doing the detailing who haven't a clue how to produce a good mechanical drawing.
I have to redo them all once they hit the shop.
The detailing guy didn't take the hint when I gave him my old drafting textbook.

On second thought, I wish they would send me even crappy drawings of a motor to make.
That would be more fun than the stuff I usually get to do.

Pat MacKenzie

Hi Pat

Brian is an old school designer and will have nothing to do with CAD.

I earn my living as a designer using CAD

The crank pin looks weak to me. the crank flange in thin then counterbalanced and to make matters worse your going to drill through it too. I betting its going to break there. often

Also what is the screw head in the combustion chamber for ?

Is the crank bore pluged ?

Hi Greg

The crank pin is the same dimensions as the Stalker 61 LT LS that Brian has been flying and developing for the last couple of years. He has a long history of designing and building winning F2C engines and the stresses on those high speed Diesels are much higher than anything seen by our low reving, decompressed glow engines.
The "screw head in the combustion chamber is actually a plug baffle - I will be posting some pictures of the version that Brian developed for the Stalker.
Yes the crankshaft is plugged with a hollow, aluminium plug. It is also worth noting that the inlet port in the crankshaft also lines up with the crankpin for better balance.

This is fascinating. I sincerely hope you will keep us posted with construction pictures etc.

Are you still going to scan these drawings in. The camara ones can not be read. Thanks!
David G. Miller
Pasco, WA

I do plan to have the drawings scanned but it may be some weeks away yet as I can't find any time off yet.

Why doesn't he put the venturi on the bottom of the engine like I seen at the worlds champ in Muncie in 2004. When engine is in the plane the venturi is then on top for easier access. Or does that make tank adjustments to critical?
DOC Holliday

The disadvantages outweigh the advantages. The tank is very high in the model making shaping the nose harder. Access to the tank is harder. The inlet hole in the crankshaft is in the worst place for balance. It is harder to make a stiff nose on the model with all the openings you would need to have to get to the needle valve etc.

On the plus side the inlet is away from the runway dust, easier to prime and the tank is further from the rear exhaust.

Brian is intending this engine to be a replacement for the Stalker engines he has in the 2 identical models he uses and is really does make engine development easier if engines are similar in layout.

Mike,
I have and used for several years three different Belko long shaft engines that have the venturi in this "reversed" condition, and can testify that everything you said is absolutely true.
The complications of construction of the model and tank location make it very difficult to get the nose of the model solid and stiff.
I've serious problems with vibration and resonance even using the stiffest of materials.
I agree this is not worth the trouble in spite of the fact that the Belko engines give a super "stunt run".

Randy C

Offset venturi - The new R&B 75 crankshaft venting utilises the same "offset" technology, although with us the venturi body is central on the casting. The offset is achieved in the internal machining of the casting.