Automotive V8 Engine Conversions for Aircraft
The pom's ability to cut helical gears, let alone hypoid bevels or double helical gears has always been rather marginal, and in the mid-1930's --- effectively non-existent.
The propeller reduction gearing exemplified the innovative design and engineering that characterized the Sabre. A compounded “back gear” drove the propeller through four pinions. When multiple pinions drive a single reduction gear, the problem of equal tooth loading becomes a major issue, particularly in a heavily loaded, high-speed application with high torsional vibration such as the Sabre reduction gear. The solution Napier devised was nothing short of inspirational. Each crankshaft drove a pair of straight-cut, first-stage pinion gears, which in turn were integral with a second-stage pinion, which drove the propeller reduction gear. The second-stage pinion gears featured a helix angle, which generated an end thrust as power was transmitted. Herein lay the secret to the Sabre’s tooth load balancing system. The upper and lower pairs of pinions were connected with a centrally pivoted balance beam. Preloaded volute springs acted on the ends of the beam against the pinions, thus ensuring that the helically cut pinions would float along their longitudinal axis as they transmitted the considerable power of the Sabre and guaranteeing equal tooth loading. Even though the Sabre was beset with numerous problems as will be related, reduction gear problems were non-existent thanks to this very innovative piece of engineering. Propeller shaft radial loads were handled by massive roller and ball thrust bearings mounted back to back, the latter also taking care of propeller thrust loads. In addition, a plain bearing was mounted at the rear of the propeller shaft that also transmitted oil to the de Havilland constant-speed propeller.
I googled "IO-550 SFC" and this came up on the first line: https://summitaviationmfg.com/wp-con...-TI_Engine.pdf
It quotes a 0.385 lb/hp.h which is 234g/kW.h although it may have got the best economy and best power figures switched on page 3. These numbers are, however, typical of what I've seen quoted around the traps for many years. As far as BMW diesels doing 198g/kW.h that's a very best-point number and there would be some celebration in the engineering office about it. Some of the old VW PD diesels are sub-200 but it's quite difficult to do and even more difficult to spread out across a useable area. The fuel consumption you see in the day-to-day use of a car is waaaay worse than these numbers, especially on a gasoline engine. If you could cruise at a steady 100km/h at 200g/kWh in a modern car you'd be seeing 3.5-3.8L/100km That's not typical of anything I know of.
It quotes a 0.385 lb/hp.h which is 234g/kW.h although it may have got the best economy and best power figures switched on page 3. These numbers are, however, typical of what I've seen quoted around the traps for many years. As far as BMW diesels doing 198g/kW.h that's a very best-point number and there would be some celebration in the engineering office about it. Some of the old VW PD diesels are sub-200 but it's quite difficult to do and even more difficult to spread out across a useable area. The fuel consumption you see in the day-to-day use of a car is waaaay worse than these numbers, especially on a gasoline engine. If you could cruise at a steady 100km/h at 200g/kWh in a modern car you'd be seeing 3.5-3.8L/100km That's not typical of anything I know of.
Nevertheless, it will be interesting to see how the diesel in that Raptor aircraft works - form memory, they're saying something like 8gph in cruise at FL 210 and 230 KTAS. If it works even half as well as claimed it will be a game changer.
Don't hold your breath on Raptor meeting its design goals. They have done some amazing stuff building their prototype but they are out of their depth when it comes to engineering and developing stuff, demonstrated amply by the way they've missed their empty weight by, what, over 600lb? That's not even weighing a completed airframe yet. I reckon it'll be even more than that by the time it's test flight ready.
The state-of-the-art in diesel aero engines is already out there and it's too expensive and heavy but under some circumstances it works. The DA42 is where it works well enough to be useful but it's not a game changer.
The state-of-the-art in diesel aero engines is already out there and it's too expensive and heavy but under some circumstances it works. The DA42 is where it works well enough to be useful but it's not a game changer.
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"The DA42 is where it works well enough to be useful but it's not a game changer."
Here is an example where modern electrics can totally fail, and it is noted that the POH was not followed.
Diamond Aircraft Industries and Thielert Aircraft Engines are at loggerheads over the cause of a double engine failure involving a DA42 Twinstar during take-off in Germany last month. The incident, in Speyer, south-west Germany, is being probed by Germany's air accident investigation bureau, but the cause of the engine failure is known to be the effect of a transient drop in the electrical voltage to the two engine control units, Diamond confirms.
The European Aviation Safety Agency has ordered the companies to find a swift solution, and Diamond's chief executive Christian Dries says his company is seeking EASA certification to install a small back-up battery for each engine's control unit.
When the crew of the accident DA42 arrived at the aircraft (D-GOAL) they found it had a flat battery and started up the engines using an external power unit. This deviated from the published operating procedure, which only allows one engine to be started with an external power unit - the second has to be started using aircraft-generated power.
Just after rotation, as the landing gear was retracted, the aircraft experienced simultaneous engine failures on both TAE Centurion 1.7 diesel engines, forcing the crew to make a belly landing in a field adjacent to the runway.
Diamond says that retracting the gear placed a load on the electrical supply from the engine-driven alternators that caused a temporary voltage drop that could not be covered by the flat battery, and the accident has shown the engine control unit to be intolerant of transient electrical fluctuations.
TAE says the problem is an airframe issue, adding that being forced to issue an airworthiness directive for the 1.7, which is set to power other aircraft types, would have a huge impact on its business. Diamond dismisses these claims and argues the control unit supplied by TAE should have been able to accept a 50 millisecond transient, but it started to reset after 1.7 milliseconds, and during the engine control unit reset the propeller system sensed the power loss and auto-feathered.
Meanwhile, Diamond has issued a service information bulletin that clarifies standard operating procedures. Dries says the question remains: who is to pay for the fix?
Blogs from Aero 2007 - Friedrichshafen
Here is an example where modern electrics can totally fail, and it is noted that the POH was not followed.
- 23 APRIL, 2007
- SOURCE: FLIGHT INTERNATIONAL
- BY: KATE SARSFIELD
Diamond Aircraft Industries and Thielert Aircraft Engines are at loggerheads over the cause of a double engine failure involving a DA42 Twinstar during take-off in Germany last month. The incident, in Speyer, south-west Germany, is being probed by Germany's air accident investigation bureau, but the cause of the engine failure is known to be the effect of a transient drop in the electrical voltage to the two engine control units, Diamond confirms.
The European Aviation Safety Agency has ordered the companies to find a swift solution, and Diamond's chief executive Christian Dries says his company is seeking EASA certification to install a small back-up battery for each engine's control unit.
When the crew of the accident DA42 arrived at the aircraft (D-GOAL) they found it had a flat battery and started up the engines using an external power unit. This deviated from the published operating procedure, which only allows one engine to be started with an external power unit - the second has to be started using aircraft-generated power.
Just after rotation, as the landing gear was retracted, the aircraft experienced simultaneous engine failures on both TAE Centurion 1.7 diesel engines, forcing the crew to make a belly landing in a field adjacent to the runway.
Diamond says that retracting the gear placed a load on the electrical supply from the engine-driven alternators that caused a temporary voltage drop that could not be covered by the flat battery, and the accident has shown the engine control unit to be intolerant of transient electrical fluctuations.
TAE says the problem is an airframe issue, adding that being forced to issue an airworthiness directive for the 1.7, which is set to power other aircraft types, would have a huge impact on its business. Diamond dismisses these claims and argues the control unit supplied by TAE should have been able to accept a 50 millisecond transient, but it started to reset after 1.7 milliseconds, and during the engine control unit reset the propeller system sensed the power loss and auto-feathered.
Meanwhile, Diamond has issued a service information bulletin that clarifies standard operating procedures. Dries says the question remains: who is to pay for the fix?
Blogs from Aero 2007 - Friedrichshafen
As I said in post #22, anything that has electronics requires a continuous stream of relatively clean electricity and switches that are reliable. Rotax 912 iS in theory gets around the Diamond problem by having a dedicated engine alternator A and an airframe power alternator B which also charges the battery. A and B are tied together at engine start, then separate with A powering ECU’s ignition, injections and fuel pumps. If A fails, B takes over instantaneously and dumps the airframe load and battery charging. There is also a dedicated battery only mode, but I’m not sure if that automatically fails over if both alternators fail.
Moral: you want a battery good for at least 30 min if everything goes wrong.
Moral: you want a battery good for at least 30 min if everything goes wrong.
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There is a lot of bad info out there on auto conversions. My Cessna 172 has an aluminum V8 on it and works way better than the dinosaur 0320 it replaced. Not only does it out perform it, but it cost less than $20 USD per hour to operate compared to $68/hr with original engine. However, not all engines make good aircraft engines, and even then, require engineering skills typically outside a pilots skill set. My C172 is quieter, consumes any automotive gas or AVGAS you want to put in it- although I avoid AVGAS due to higher price and i need to change oil and clean plugs a lot more often due to the lead- and parts are cheaper....not to mention it doesn’t pollute the air as much. It even has OBD which displays fault codes if something goes bad, making maintenance easier....when was the last time you saw a modern car broken down on the side of the road? It’s also easier to fly with no mixture control or carb heat. Even the certified diesel aircraft engines use an automobile engine block.
the right converted engine is way better than the 1940 stuff the industry still forces down our throat, and in my opinion, more reliable. I currently fly the B787 and everything is electric, and very reliable. The only thing holding technology back is Lycoming and Continental that have not needed to improve their product because they have a monopoly so why spend the money. Certification agencies share much of the blame as well by using 60 year old cert regulations and demanded expensive cert process..
the right converted engine is way better than the 1940 stuff the industry still forces down our throat, and in my opinion, more reliable. I currently fly the B787 and everything is electric, and very reliable. The only thing holding technology back is Lycoming and Continental that have not needed to improve their product because they have a monopoly so why spend the money. Certification agencies share much of the blame as well by using 60 year old cert regulations and demanded expensive cert process..
Mercury Marine introduces a 7.6 litre V12 marine engine rated at 600 hp rated at a light duty cycle (ie pleasure/recreational boating). They will launch a 500hp version designed for meduim duty commercial rating 9around 3000 hrs per year, 80% time at full load), 3000+ hrs between overhauls.
Here is a new V12:
It is a newly developed aviation engine, certified, done by some former formula one car engine developers.
https://www.flyer.co.uk/red-aircraft...2/?cmpredirect
It is a newly developed aviation engine, certified, done by some former formula one car engine developers.
https://www.flyer.co.uk/red-aircraft...2/?cmpredirect
Hey Dawgie,
Lots of engineering required. Auto engines HATE running for long times at constant RPM. The lube system relies on RPM changes to lube the cylinders for a start.
That's why Subaru boxers aren't converted to fly much. An outstanding engine but need RPM change to survive. I've been running highly tuned Subis for many years and this is well known. An hour on the freeway with no traffic can be risky when you're pulling 200Kw at the wheels. Constant RPM is a no-no. Maybe keeping the speed limit would help??
Lots of engineering required. Auto engines HATE running for long times at constant RPM. The lube system relies on RPM changes to lube the cylinders for a start.
That's why Subaru boxers aren't converted to fly much. An outstanding engine but need RPM change to survive. I've been running highly tuned Subis for many years and this is well known. An hour on the freeway with no traffic can be risky when you're pulling 200Kw at the wheels. Constant RPM is a no-no. Maybe keeping the speed limit would help??
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Dawgie?
not sure what your engineering background is but most issues with auto conversions are engines running at or near manufactured HP and torque ratings, and no transmission to act as a buffer, not to mention pulse fatigue and shaft alignment issues. As far as constant power stresses go at prolonged cruise settings, again mist auto conversions operate near 100 percent of max rated power. Marine engines have far more stress than aircraft engines and do fine.
Check out www.corsairpower.com. They have a V8 engine for Cessna's with a lot of info on the topic.
not sure what your engineering background is but most issues with auto conversions are engines running at or near manufactured HP and torque ratings, and no transmission to act as a buffer, not to mention pulse fatigue and shaft alignment issues. As far as constant power stresses go at prolonged cruise settings, again mist auto conversions operate near 100 percent of max rated power. Marine engines have far more stress than aircraft engines and do fine.
Check out www.corsairpower.com. They have a V8 engine for Cessna's with a lot of info on the topic.
Looking more at that RED - https://red-aircraft.com/product/ seems like a wow, Jet A1, 500hp!
As for the Subi, surely with modern FADEC could easily set up RPM changes every xx mins, would even help keep you awake
.
What were those V8’s years ago Orenda?
As for the Subi, surely with modern FADEC could easily set up RPM changes every xx mins, would even help keep you awake
.What were those V8’s years ago Orenda?
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Most interesting, nomorecatering! 
I wonder how one of those Air Tractors would go as a Glider Tug?
I wonder how one of those Air Tractors would go as a Glider Tug?
Some auto engines I have worked on have oil holes in the con-rods to direct a jet of oil up into the cylinders from underneath.
Other engines I have seen have oil jets mounted at the bottom of each cylinder, spraying upwards.
For compeletness I should Deltahawks now certified engine. Some interesting possibilities in a 6,8 and 12 cylinder configuration as it appears modular in nature.