Why New Aircraft Engine Ideas Rarely Succeed

The Dyna-Cam was one of my favorites.

Great specs, >600ft-lb torque in a 200hp engine. I think it suffered from cam wear issues, plus all the other issues that small start-ups face.

 

Would seem difficult to seal the ends of the cylinders, plus lots of rotating mass. Wonder if they were (are) trying to capture the concept of the Dyna-Cam but have to work around the Dyna-Cam patents.

 

Really neat, thx for posting!

 

Let me amend that. Believe the big issue was cylinder wall scuffing due to side loads placed on the connecting rods from the cam.

 

VW/Porsche countered that with off-centered wrist pins on the pistons. No problems. In my younger life, my four sons and I went through over 10 VW's of various models including airborne applications. Great little engines.

 

Off set wrist pins are pretty common and are a band aid to compensate for the fact that the rod ratio is a mess. Too short rods generate high side loading and are sometimes used in lower RPM, lower output engines where the engineers were willing to make that exchange when smaller overall size was considered a more important factor for a given application. Substantial pin offset is typically found in engines not known for long life spans. Rod ratio becomes a very big issue in modifying engines when output, RPM, and sometimes stroke are increased. Lots of interesting piston designs result so as long a rod can be installed as possible.

In the revolver engine there were no rods in the conventional sense, just a variation of the wobble plate.

 

Yeah, that's what I thought about those rods and pin things, too, Brian. Geeze, makes me realize how much I don't about this engine stuff. The wobble plate configuration reminded me of the engine driven variable displacement hydraulic pumps on the P&W 707 engines and probably many others.

 

My favorite is the 1933 Besler,which was powered by a steam engine.

 

Remember the Pond Racer? Powered by two Nissan racing engines. When one of them blew, it resulted in the end of the aircraft.

 

That really didn't have to happen. The engine builder was way overpromising. The motors were never going to deliver. Rutan really wanted out of the engine deal and try something else. His confidence in the engines and in the supplier was completely gone but the guy writing the checks over ruled him and pushed ahead.

No one with any sense ever believed those motors , A. Would live at power levels needed and B. Ever make the power levels needed. They didn't.
The motors didn't stay together long enough to make the start of a single race.


The engine builder was from dream land.

Stupidity cost that pilot his life.

 

I'm in total agreement! Like they always say, " There's no substitute for cubic inches."

 

They were 3 liters or so running on alcohol and turbocharged. They ran them at 8000 RPM and were intended at that speed to make 1000 HP.

They kept burning pistons and at that boost it made so much crank case pressure they would blow all the oil out while trying to sieze and you just blew a couple of gallons of a combustible material all over a hot engine. In that process the rods came out of them. The process was well known because it happened so often. They just kept screwing new engines in it and doing it over and over. Pond just kept writing checks hoping for a different outcome.

3 liters making 1000 HP has a life measured in just a few seconds. Even a racing plane needs a few minutes of engine. Running the Merlins at 2800 or so, whatever they are making now burn pistons regularly too but they have 27 or so liters.

 

Okay, so we're talking about putting automotive engines in aircraft. What about the aircraft engines that have been put in automobiles?

https://www.airspacemag.com/flight-today/jay-lenos-airplane-engine-collection-180977799/

 

They even put a WW-I style rotary engine in the Adams-Farwell, except it had an oil return where the WW-I rotaries used total loss lubrication.

Adams-Farwell at the Pebble Beach Concours d'Elegance - YouTube

 

In my opinion an equally dumb idea. The basic characteristics desirable for an aircraft engine are contrary to the characteristics desirable for a car. The few powered by Merlins were a waste of perfectly good engines.

 

There were a couple of pre 30's cars with either radials or rotary engines. I remember seeing a couple of them at the old Harrahs Collection but I never paid them a great deal of attention.

 

What about radial-engined motorcycles?

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Don't forget that many U.S. tanks at the outset of WW II were powered by aircraft radial engines, and the British used inline aircraft engines almost exclusively, changing from the Liberty engine to the Meteor (basically an unsupercharged Merlin) at mid-war.

(I know, I know, we're getting a bit off-topic here.)

 

That Gilmer belt drive looks pretty scary.

 

Leno has a turbine motorcycle but throttle lag is prodigious, even when closed.

"Well it sounded like a good idea"

 

In a tank not such a bad idea. We have been using turbines for a long time now. Only issue has been keeping dirt out of them. Well I guess gas mileage aint great either.

 

Bob,
There is one substitute for cubic inches - cubic money.