Which Engine???

[fly_tornado]

You should write a book Matthew

 

 

[Jethro Belle]

I like the design principle of the D-Motor in that the valve design isn't interference. Its a side valve.I was drooling over this 115Hp lycosaurus experimental which apparently still doesn't benefit from electronic fuel metering

 

233 Series

Yes it is interesting how USA is very attached to their carburetors so it is worth understanding. It places them way behind in the power game because the venturi restricts airflow and looses several percentage horsepower. Poor mixture distribution leads to more power derating, such that changing from carburetor to MPFI gives 10 to 20% power increase (on car engines)!

 

They aren't stupid however. By restricting the air intake the engine remains more lightly loaded. Those old enough to know the anemic power than the VW air-cooled boxer (the beetle and Kombi engine) could reputably be pushed along at full throttle for hours because it was impossible to get enough air in and exhaust gasses out to overload it (This wasn't my experience of Flubdubs, which I why I am wary of high power VW aeroderivatives). Hopefully some VW aeroengine cognoscenti will post clarification on this. Anyhow I suspect upping the power output on an Lycomtinental without other "improvements" may be at the expense of TBO and reliability (it applies to all engines).

 

Also, unlike road vehicles, aero-engines operate at fixed speeds/loads most of the time, so the flexibility of fuel injection at part loads is of little advantage.

 

Another factor is that sticking with regulated, approved carburetors avoids litigation risks (something that USA has lead the world in).

 

Finally, fuel injection development has been a European (notably Bosch) with early attempts having dismal reliability. USA with cheap fuel found it easier (and initially more reliable) to add cubic inches to get the power.

 

The problem in aviation is that adding unnecessary CCs increases weight above the competition and carburetors can't match current fuel injection, so you have heavish, highish fuel burn, reliable Lycomtinentals.

 

I understand that fuel injected aero-engines don't experience icing like occurs at the reduced temperature at the carburetor venturi throat (Can anyone confirm an icing problems with their fuel injected engines please?). With quality sensors and ECU set up for aviation, correction for altitude, temperature etc can be precisely controlled.

 

I don't like electronics myself because I am old enough to remember failure after failure including early fuel injection, but that seems to be resolved, so I agree that fuel injection is the best way to go, except maybe on very small single cylinder engines. Many USA pilots are my age however, so I suspect the market also dictates what Lycomtinental sells and their big market is USA. Lycomtinental decisions will be made by accountants, lawyers, marketing and the stock market, not start-up engineers.

 

If you like carburetors that is great. They work and are well proven. I doubt it is worth retrofitting fuel injection, unless you are experimenting for the sake of it. The above is all opinion and input from anyone with objective direct experience will override anything stated

 

 

[facthunter]

Motors that rev to astronomical revs but only do it for short periods won't sit on high power for ages. All the high revving motors Porsche Bugatti etc have been outstanding failures as aircraft engine makers. Ultra long stroke marine diesel 76 RPM are super efficient high boost engines running on TAR .Reversals are vibration generators and fatigue inducing actions. Piston speed limits have a lot to do with lubrication difficulties. It can happen with large dia Journals with bearings too. No one is STOPPING anyone making a good aero engine . There's few examples of the big breakthrough though. Piston engines are basically self destructing gadgets. Jabiru was never much worse than "good" big radials if one cared to investigate. using the right parameters.. Not instinct or rumour and running out of fuel. Nev

 

 

[pmccarthy]

Herschell Smith's book on the history of piston aircraft engines is a great read. The small details that make a big difference. And it explains why we ended up with small flat opposed engines after all that evolution.

 

 

[Jethro Belle]

All the high revving motors Porsche Bugatti etc have been outstanding failures as aircraft engine makers.

The Rotax 4 strokes are high revving (hence my continued statements similar to yours).

 

My understanding was the Porsche Flugmotoren was complex and expensive (a reduction drive was not viewed well in GA back then), not that the high rpm wore out their cylinders. Early pilots reports were similar to those received from Rotax owners (smooth refined engine). There were so few built I doubt crash statistics or TBOs achieved prove much. I haven't checked them. Anybody have the data? Mr Wikipedia confirms my understanding that it was not commercially viable for Porsche to provide such a small number of engines (which ended up not being a modified 911 motor) in the Litigious USA market (From memory Porsche was in serious financial trouble because of it).

 

Bugatti

 

In crash statistics I saw for experimental engines the internals of auto-derivatives were less accident causing than Lycomtinentals. That was the only statistic they were better. I suspect electronics and peripheral malfunctions, more than the core engine, were problems for Porsche also.

 

I agree in general with what you are saying, but high revving does not automatically equal unreliable. It has to be better engineered to deal with higher stresses, wear and heat.

 

Engines run at high revs run into thermal induced failures if they are not designed to cope with the significant heat load as a steady state operating condition. Overheating the cylinders and rings will cause major wear due to lubricant film breakdown. The exhaust valve guide is usually high wear in heavily loaded engines not designed for it.

 

I think we agree:scratching head: Perhaps your post was a general warning to readers. My issue is you appear to be damning all high revving aero-engines outright, no-exceptions.

 

 

[jetboy]

I have considered the 3rd,.or.4th generation 2200's, and may still choose.it. What would be your recommendations?

only new (gen4) for the Jabiru, but postpone this decision until there is an established track record.

you could safely choose a timex 912 and just overhaul the gearbox, they have a good record and flight schools often renew them rather than overhaul.

 

the D-motor is my personal 1st choice, it comes down to price and that depends on the country. In my case, the existing engine mounts are for Jabiru / D-motor / ULpower and that represents a big difference. The ring mount for the 912 is pricey but essential and adds to the cost.

 

 

[facthunter]

I couldn't stand a high revving piston engine in a plane. I can't stand them in a motorbike either. I don't want to listen to things doing 10,000 revs when it's trying to self destruct. It's the RECIPROCATING thing. and vibration and STRESS Exhaust pipes cracking, manifold rubbers engine mounts. Horizontally opposed 4 cylinder engines are not optimum in some important aspects ALL the pistons become stationary simultaneously, twice per revolution. At that point their flywheel effect is ZERO. It's not a coincidence that flat fours are the best crankshaft breakers and clutch centre wreckers. You can't feel the problems it has, but they are there.

 

Re the sidevalve "D" motor I wonder what's going on there? . It's compact and should be simple to make providing all the calculations for the castings and the quality is there but sidevalve usually has bore distortion to a bigger degree than OHV motors.

 

Good aero engines are not a dime a dozen. Plenty have tried. Nev

 

 

[Marty_d]

Infernal combustion engines will soon* be a thing of the past, in aircraft as well as cars, trucks and whatever else needs an engine.

 

*"soon" being a fluid concept within the range 5-50 years

 

 

[mnewbery]

Subaru owner joke:

 

Knock knock?

 

Who's there?

 

conrod three!

 

 

[mnewbery]

Racing Secrets

 

On the same website is @fly_tornado 's favourite engine with a turbo on it.

 

The website also has a tab waaaaaay off to the right just for @fly_tornado. It could be turned into a book. Or not.

 

While on the subject of the Takeoff-ul (modification of the R1100) TBM11 as noted in post #47, the editor stated he thought the cruise demand was around 38hp at 70KIAS given the 2.6 GPH fuel consumption. I think this amount of cruise demand even at 5500 RPM would contribute a lot to overall longevity.

[mnewbery]

This could be worth a read. It appears directly relevant to the thread.

 

Alternative Engines Volume 4 preview (Opens in ISSUU reader)

 

 

[fly_tornado]

[Jethro Belle]

Infernal combustion engines will soon* be a thing of the past, in aircraft as well as cars, trucks and whatever else needs an engine.*"soon" being a fluid concept within the range 5-50 years

About the same time they can work out how to close down all coal and nuclear fired power stations, do you think? When do you predict Lithium battery energy density and safety will match JetA1? How will Nev cope without the incessant drone of a Lycomtinental All fun. Don't take anything asked seriously.

 

 

[fly_tornado]

Lycons don't run on JetA1 one of the most spectacular failures of that technology

 

 

[Jethro Belle]

Lycons don't run on JetA1 one of the most spectacular failures of that technology

It was a blanket claim, so I provided examples that will take a lot of beating

Yes it is unfortunate Lycons don't, but that is the diesel engine thread. Not so much a failure as the laws of physics as engineers have managed to apply them so far, while constrained by lawyers and accountants.

 

 

[facthunter]

There's been plenty of diesel Aero engines gong back into the mid 30's,, mostly confined to duties where the economy was used to advantage. Several Radials were made and the Junkers Jumo a bit of a complex thing.. Radials supercharge well It's almost necessary to get the fuel to distribute evenly. They also have very balanced internal loads in steady cruise . Nev

 

 

[fly_tornado]

Lycons are legacy technologies, the FAA has abandoned the unleaded fuel trial just recently. its not looking good for a lot of older GA aircraft

 

 

[Jethro Belle]

Lycons are legacy technologies,

That is a bold claim! Lycoming have approved mo-gas for some of their engines but have some justifiable reasons why using pump-gas, as they define petrol direct from the service station, as being non-approvable (recently read it on their web site).

 

I am not a big fan of Lycons, but I would be proud of the safety legacy they have built. New is not automatically better

 

As I understand it the unleaded trial AVgas 82 UL was running as a two grade system that never gained traction, so the original 100LL is continuing. Did I miss something?

 

 

[Jethro Belle]

the Junkers Jumo a bit of a complex thing

Its back

 

Gemini :: Aviation

 

Gemini :: Gemini 125

 

What do you reckon to that Nev.

 

 

[pmccarthy]

Mo-gas versus pump-gas? My O-360 has been running mogas for years under a Petersen STC. I buy it at the BP pump in town.

 

 

[Old Koreelah]

the FAA has abandoned the unleaded fuel trial just recently...

Hope that's not true, FT. I've been looking forward to a lead-free fuel of reliable quality for my Jab.

 

 

[mnewbery]

More verifiably incorrect information from @fly_tornado.

 

Suspended does not equal abandoned. Shame on you.

 

Are We Gonna Get A 100LL Replacement Or Not? - AVweb Insider Article

[Yenn]

My Lycoming runs well on mogas. I don't use it because the mogas caused bubbles at the rivet heads on the tank. It seems that mogas can affect the sealant used when building. Back to using avgas and the leaks were sealed with Loctite 290, but it still looks unsightly.

 

 

[fly_tornado]

More verifiably incorrect information from @fly_tornado.

 

Suspended does not equal abandoned. Shame on you.

 

Are We Gonna Get A 100LL Replacement Or Not? - AVweb Insider Article

 

"Suspended" because the fuel submitted aren't fit for purpose, where are the alternatives?

[skippydiesel]

Its back orGemini :: Aviation

 

Gemini :: Gemini 125

 

What do you reckon to that Nev.

Seems to be a lot of optimistic motherhood statements and not much else - in the schematic side view the alternator is shown being belt driven at the prop flange - I sort of think this is the same layout as the Lycomtenental - presumably the prop must be removed to replace the belt - why not stick the assembly at the back with its own pulley or even better gear drive it ???