Why New Aircraft Engine Ideas Rarely Succeed

I crewed on a land speed record car. It broke the record on its 1st full pass (1st pass was a short pass to test systems). It went over 340 ultimately. I asked the owner "So, about $1000 per MPH?'. He said "pretty close".

I think with airplanes you need to add another digit.

 

Talking engines. We have a 2003 Honda Odyssey with 2010 K miles on it. This has the best engine that I have every owned. I have been religious about care and maintenance and it is still powerful, responsive, quick, and totally reliable. It uses about 1 quart of oil in 3000 miles and has had no other problems. The belts were replaced at 196k and showed no signs of failure. I would have another when the times come but it'll be a long time from now.

 

Bob- I hope you meant 201K and not 2,010,000 miles.

 

OOPS! Two hundred ten thousand, 210K. You have to expect that from a 950K year old guy. Or is that just 94.9 with no K. I really don't care, I'm having a good time with all of this.

 

As far as new engines?

This sure looks interesting & rather promising for small aircraft...

https://www.liquidpiston.com/

 

These guys have been at it for over 15 years, since before 2006. That's a long time. always hear "looks promising". Not sure what the problems are.

"The architecture is based on a “High-Efficiency Hybrid Cycle” (HEHC) thermodynamic cycle, which borrows elements from Otto, Diesel, Atkinson and Rankine cycles.
The HEHC cycle can be implemented in a variety of ways; LiquidPiston is developing an implementation that uses a separate rotary compressor, two isolated combustion chambers, and a separate rotary expander."

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Sometimes also called green grease.

 

Cubic inches? A most magnificent failure was the 36-cylinder Lycoming R-7755, probably the biggest piston aircraft engine ever built. I believe that only 2 were built, and the Smithsonian still has one!
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I really like piston engines but someone should have sent butterfly nets after that entire design crew.

God I am glad we have jet engines. The 4360 should have been lesson enough. The law of diminishing returns hit the wall very hard at about 3500 inches.

Just keeping on piling on more cylinders and more banks of cylinders works fine for stationary diesels.
But not for high speed gas engines.

 

If you''re wondering, that Lycoming monster was sort of a hybrid between traditional radial and inline engine design. It had 9 banks of 4 inline cylinders arranged radially around the crankshaft, and it was liquid-cooled.

 

With 4 crank pins and 4 master rods no doubt. Keeping all the sins of inline and radial with none of the virtues.

Kill them before they design again.


All that for an anticipated 5000 HP and a svelte 6000 lbs. . Talk about diminishing returns.

 

something 'new'/interesting: REVOLUTIONARY new INLINE 4 - ALFADAN BIG BLOCK i4 ENGINE
https://www.startengine.com/alfadan

this vid is from a Youtuber not associated with Alfadan.

Jump to 15:50 (read vid description & timestamp - first 15 min. talks about problems with large bore i4's)


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Thats pretty exciting. Inline 4 is one of the best, if not the best, most efficient configurations for a water cooled piston engine. Output per displacement is typically great. If they have solved the inherent secondary vibration issue that is indeed a game changer.

Non cam operated valves have been under experimentation since the early or mid 80's. by a lot of companies. Solenoids had too many issues but I had heard there was considerable progress made with pneumatic.

Mahle is huge in the piston and rod business, without doubt the best piston company in the world so it will be very interesting to see what they have dreamed up with a rod that makes this possible. They are the leader in powdered metal rods. We'll see.

Thanks for posting that. .

 

Koenigsegg's FreeValve system
https://www.freevalve.com/freevalve-technology/

Jump to 5:00 for FreeValve discussion


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When I worked for the Sunshine Buick Co. in Sarasota, I learned a bit from the owner who was an engineer. He supervised the shops that built P&W engines during the war and he told me that the worst configuration for a crank shaft was with an inline 8 and the best was a straight 4. Anything longer has distortion issues from power impulses. The straight 6 and 8 crankshafts assume an "S" shape at high power inputs and require many main bearings.. I always think of the 4 cylinder Meyer-Drake / Offenhauser(spl) engines that ruled the Midget race venues for so many years...and the great sound that they produced.

 

I have seen it thanks. As small as they are I just consider Koenigsegg the next level of experimentation.

 

Modern Rotax engines are incredibly; reliable, inexpensive, low operating costs, and less sound/vibration.

I have terrible opinions of Lycomings and Continentals.


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