"Green" Aviation Show

[Michel Kieffer]

Thank you for these interesting figures.

Michel

[Michel Kieffer]

Engine quality (updated following remarks from Storm Bird)

The economic quality of an engine can be defined using 2 indicators:
- the specific consumption (kg of fuel / hp.h)
- the mass quality (kg of engine / hp)

Here are some specific consumption figures (subject of the update):
- ROTAX 912: 0,20 kg / hp.h (ROTAX and various sources).
- LYCOMING: 0,209 to 0,216 kg / cv.h (design in the 30s; sources: flight manuals DR400 120 cv, DR400 160 cv, TB 9, CESSNA 172 ...).
- THILERT (diesel): 0,185 kg / hp.h (2000 diesel design, sources: PILOT INFORMATION).
- SMA (diesel): 0,170 kg / hp.h (diesel design 1990 and still under development; source: CESSNA 182 SMA flight manual).
- (Note that the 2 T sweep without injection are at 0,360 kg / hp.h)

And some ancestors (the good, not the bad, and of higher powers):
- JUMO 4: 0,180 kg / cv.h in 1928
- JUMO 204: 0,155 kg / cv.h in 1931
- etc… including 2 T valves identical to the recent Wilksch. Such a configuration allows compression rates much higher than 2 T scanning, which explains correct specific consumption with excellent mass qualities ... resulting in a beautiful and very beneficial converging spiral (see pages 9 and 10 http://www.hkw-aero.fr/pdf/comment_atte ... ectifs.pdf ).

As for the mass quality, it is between 0,6 and 1 kg / hp for the best engines of the 30s.
Current petrol engines are above 1 kg / hp.
As for the aero diesels, their deplorable mass qualities (of the order of 1,5 kg / cv or more) greatly degrade the balance sheet compared to petrol engines.

The problem being that poor mass quality is accompanied by a spiral coefficient (cf. cars http://www.hkw-aero.fr/pdf/coefficient_spirale.pdf ) going in the wrong direction (see page 4 http://www.hkw-aero.fr/pdf/comment_atte ... ectifs.pdf ). Hence the observation: low specific consumption can lead to higher overall consumption due to excessive mass (cf. aerosol diesel).

In conclusion, for the engine part, the green aviation show should honor the engines of the 30s (good engines)!
It is nevertheless interesting to note that there has been no significant progress since the 30s (taking as reference the good engines of that time).
80 years with very little progress and some serious regressions, highlights that there is hardly a revolution to expect from the engine side.

Michel

PS: this debate gives me an idea: make a graph of specific consumption and mass qualities depending on the time.

[oiseautempete]

For the consumption of Lycosaurs and other contis, in reality the specific consumption is much higher because:
-Wealth is manual (automatic on Rotax)
-the pilot manually adjusts his richness according to his cylinder head and exhaust gas t ° (EGT and CHT), in the middle of the tolerance while the manufacturers' measures are taken "at the limit" ...
To the old airplane diesel, you can add the excellent (but rare because WWII) Clerget 2 cylinders which reached the same mass / power ratio as a petrol engine of the time ...

The SMA was designed by the Renault F1 team when they were put on a date, in other words by people without any experience in diesel and even less in aircraft engines, hence questionable choices ... j also talked to a former technician on the team and he told me that it was big DIY to the point that the first proto engines exploded
Designing a certified engine is EXTREMELY expensive because of the compulsory validation tests and involves high sales prices, even Porsche broke its teeth despite the excellence of their engine (based on that of the 911 turbo), and the promising diesel Zoche does not end with certification while it has been running for almost 10 years ...
The classic aviation is sclerosed by excessive regulations which prevent or at least considerably slow down the technical progress, it is necessary to see the ridiculous serial of the planes tractors of gliders, which having adopted less noisy propellers but not certified with the type have had all the trouble in the world to be able to fly, and under a foreign registration because the chilly DGAC had refused the exemption ...
As for the aviated road engines ... they are above all road engines, therefore not at all suitable for departure (ex: on a VW you have to saw a lot of material on a block and the crankshaft is not at all designed for support the traction of a propeller ...) and most often you need a reduction gear because the road engines are fast, (optimal propeller rotation speed between 2000 and 2400tr)

[Michel Kieffer]

Here is some interesting information ... let us add that the road motor vehicles with another fault: the lack of durability. When the long development approaches its end, it is no longer manufactured.

Michel

[oiseautempete]

let us add that the aviated road engines have another defect: the lack of durability. When the long development approaches its end, it is no longer manufactured.

Michel

Indeed, road engines evolve rapidly and it is rare today that the same version is more than 5 years old: this is due to the "severity" of the antipollution standards ... Thus for the diesel, it was necessary to make large changes to pass the euro 5, while many blocks could make the euro 3 and 4.

From this point of view some motorcycle engines are more interesting because they are stable for longer, moreover the very durable suzuki bandit 1200 engines have been recovered by "Vija" for the aircraft ...
At the same time, some aircraft engines such as the Walter 4 and 6 Czech cylinders have been produced almost identically for 80 years ... too bad that the small Salmson 9-cylinder star engines, very famous for their reliability, have not survived, because the small Salmson engines (from 40hp) have long been manufactured by the English subsidiary (Salmson, French manufacturer among others of aircraft engines, airplanes and automobiles still exists but no longer manufactures that hot water circulation pumps for heating).
For the record, the observation and liaison planes "Criquet", "Fiseler Storch" manufactured in France until the 50s, were powered by a 9-cylinder Salmson star-shaped 300hp instead of the inverted V8 engine. German "Argus" original ...

[Other]

Hello

- LYCOMING: 0,209 to 0,216 kg / cv.h (design in the 30s; sources: flight manuals DR400 120 cv, DR400 160 cv, TB 9, CESSNA 172 ...).

Maybe designed in the 30s, but those who work on these engines know that the engines are fitted with modern materials.
Ceraminil cylinder, forged durlumin piston, laser segment, roller cam, sodium exhaust valve, electronic P-Mag ignition, tuned exhaust pipe, and several versions an increased compression rate, or certain Lycoming has a specific consumption fairly close to good engines
or 0,45lbs / Hp.
Do not forget that for safety reasons rarely we walk with a ratio as poor as in cars, the fragile point is the temperature of the valves, as all these controls are manual and that few pilots monitor EGT at every change of diet every change of plate he leaves it on the rich side. reliability, safety comes before consumption.
Ask a pilot, how many RPM does your engine run at full throttle when going up, full throttle in level 4 out of 5 I will tell you I don't know

Like almost all reliable rustic engines, the best specific consumption is often in a fairly narrow speed range and even narrower on those with a compression ratio of 8,5 and 9,7 at 2350rpm for the O-290 D-2
in the design of these engines the priority is reliability and endurance. Um engine which has 2000 hours compression weakened, the differrence on the power is very thin with a new engine

A Lycoming that the manufacturer recommends an advance of 18 degrees will operate without much concern at 30degrees (a little limit in full power climb) but economical at 60% of its power in level.
As for fuel, a good number of drivers in remote regions operate it on automotive fuel. (my neighbor spent his life with auto fuel in his engine seaplane o-320 150hp)

What limits the compression ratio on air-cooled engines is the high temperature of the cylinder heads 380F to 400F
an airplane engine must have its full power at 2600rpm
We can compare the reduced Rotax, Subaru, and GM we forget to talk about power and consumption at the propeller,
If Rotax with air cooled cylinder heads there would also be a lot of problem.
To be able to recondition several Lycoming, even after 2000 hours the wear of the crankshaft is so minimal that you reassemble it with standard bearings, what suffers the most is at the level of the valves because of the heat and thermal shocks that the pilots are driving the engines.
Another rule in aviation is the simplicity the vest which is not installed does not break.
Russian and North American manufacturers have understood that, if you look at an Antonov or a Beaver, the tool chest is limited to a small box and a mechanic or often the pilot is able to make a repair in the bottom of the tundra.
Andre

Very rare are the pilots who operate their engine, on the economic side (to exceed the peck of the EGT) most of them tint on the rich side even a large number do not touch the mixture, just to stop it, and many Continental engine airplanes 65Hp at 90 hp the mixture is attached full rich with a pin no zipper inside, the mixture is good when it is -20, just to say that consumption on an airplane engine is not yet the priority. For us northerners, we take this into account, because of the autonomy, and often we have to take cans of fuel for the return to distant regions, some have fuel caches in the forest.


A tank of fuel in the forest, not too far from the edge of a lake.

[Cuicui]

From this point of view some motorcycle engines are more interesting because they are stable for longer, moreover the very durable suzuki bandit 1200 engines have been recovered by "Vija" for the aircraft ...

When will Jean-Claude Lefeuvre's vane engine arrive?

[oiseautempete]

Maybe designed in the 30s, but those who work on these engines know that the engines are fitted with modern materials.
Ceraminil cylinder, forged durlumin piston, laser segment, roller cam, sodium exhaust valve, electronic P-Mag ignition, tuned exhaust pipe, and several versions an increased compression rate, or certain Lycoming has a specific consumption fairly close to good engines
or 0,45lbs / Hp.
Like almost all reliable rustic engines, the best specific consumption is often in a fairly narrow speed range and even narrower on those with a compression ratio of 8,5 and 9,7 at 2350rpm for the O-290 D-2
in the design of these engines the priority is reliability and endurance. Um engine which has 2000 hours compression weakened, the differrence on the power is very thin with a new engine

What limits the compression ratio on air-cooled engines is the high temperature of the cylinder heads 380F to 400F
an airplane engine must have its full power at 2600rpm
We can compare the reduced Rotax, Subaru, and GM we forget to talk about power and consumption at the propeller,
If Rotax with air cooled cylinder heads there would also be a lot of problem.

Russian and North American manufacturers have understood that, if you look at an Antonov or a Beaver, the tool chest is limited to a small box and a mechanic or often the pilot is able to make a repair in the bottom of the tundra.
Andre

Yes I know that there have been slight improvements, but nicasil cylinders it is only on high power engines because it is expensive, the others have a simple chrome plating or nothing at all ... forged pistons this is not an advantage: they are heavier and a priori useless on a slow engine ... sodium valves, it is a very old technique (30s) and in Europe many do not want it in their engine plane because there are a lot of cases of rupture in the welding ... in high-end cars (BMW / Porsche) there are also but they use a new technique much more reliable than butt welding classic, electronic ignition only concerns new high-end engines, the older ones still have the old unreliable magnetos, the exhaust tuned? considering the delusional price of this option (because it is an option), very few use it ...
Please no non-metric measures as little understandable here as Chinese, even in England it has not been used for 15 years ... another proof of the fanatic conservatism of North America ... the same one that made prefer an old continental 0-200 to the Rotax 912S for the skycatcher ...

The compression ratio of the most modern engines is 13/1 and with simple automotive gasoline ..., they use a reduction gear that multiplies the torque while weighing yet much less heavy ... these differences, it is among others which allows to obtain very low consumption impossible with an old mechanics.
What saws me off is the ridiculous cold compression of conti / lyco engines: with 1 hand you can easily brew a 7 liter engine with 180hp ... while even with a Jabiru 2200 of 85hp yet also cooled by air and without reducer, it's hard even with 2 hands ...
In Europe, it's like in Japan: we like cutting-edge technology, it's just a question of philosophy ... that's why it's been 10 years that European customers have been asking for an injection on the 912 (which would allow to gain 10% in consumption and smoother operation), but the owner of Rotax is Canadian ...
Of course, in the middle of nowhere it's good to have rustic equipment easily repairable, but in Europe it does not have the same interest because the maximum distance between 2 villages is perhaps 20km in the most corners lost in France ... and our fuel is 2x to 3x more expensive than in America ...