Peter wrote:
That is from 1993, when almost nobody knew about engine management.
But doesn’t engine management exists since decades (remember Lindbergh showing his comrades in the Pacific region to fly with low rpm high throttle markedly extending the range)? Low tech, but anyhow. You are right, computerized engine control only exist in Injection-Rotax, Thielert and Diamond Diesel, since 10-20 years.
I don’t quite agree.
If you put a FADEC onto an IO540, it would end up doing more or less what a “smart” pilot does already: climb initially full rich and then leaning for constant EGT, set peak EGT in cruise, possibly with a lower rpm, and above a certain altitude enrich for best power.
That is what the FADEC on my VW diesel (mine is without the VW software cheat, and I will keep it that way, because the “fix” cripples low end torque 
) does. Well, it also varies the ignition timing, which has useful second order benefits. And other small tweaks to adjust for OAT variations, etc, although possibly you don’t need to measure OAT if you are leaning for a certain % of oxygen in the exhaust.
So a FADEC controlled Rotax isn’t going to be immune from the discussion of which is the optimum strategy for descending (or climbing). Burning petrol is burning petrol. If you fly a Rotax, a Diamond, etc, beyond a certain % of the operating ceiling, it will depart from peak EGT and start to go increasingly rich – just like my VW does, or like my IO540 does. In fact when you floor the accelerator in a modern car you are pouring fuel down the exhaust.
The only difference is that you don’t have to think about it. And if you wanted to think about it you might have less control over it.
Potentially a water cooled engine could be climbed at peak EGT, IF (a big IF) you have the cooling capacity, which is unlikely to be the case over the entire envelope (e.g. climbing out of La Paz, or even way short of that e.g. ISA+20C). But the salesmen will hate that because the rate of climb will be crippled, relative to going 150F ROP. So I bet nobody in the business (cars or SEPs) is doing that. Especially if you want to avoid detonation with UL fuel.
Indeed Lindbergh knew about leaning, etc, but he was way ahead of his time.
All the large piston powered airliners/bomber had a dedicated engineer tuning the engine at all phases of flight. The know how is not a new thing. Also, it’s only relevant if you for some reason have to manage fuel, which is secondary to power and engine health.
Even a modern FADEC SEP engine is designed for power and engine health first. You can always save fuel by flying slower.
The FW-190 had a single lever mechanical “FADEC”, almost 80 years ago.
Anyway, I think everyone who has flown a glider knows that a continuous descent with as little power as possible, preferably none, definitely saves fuel
LeSving wrote:
The FW-190 had a single lever mechanical “FADEC”, almost 80 years ago.
The Antonov 2 also has automixture. I really wonder why no GA plane has it. It would save a lot of head scratching and misuse of engines.
I don’t believe you can implement any kind of auto mixture which works well enough, without sensing either the EGT peaking (by measuring the EGT and using the hill climbing method to set the mixture, which is how we pilots do it manually) or measuring the exhaust oxygen (which is how it is done in cars, and it sets the operating point where there is a specific O2 % in the gas).
The latter method introduces a failure mode: the oxygen sensor does fail, and is a fairly regular replacement item in cars. Not a showstopper but you would need a reversion mode. In cars you have a watercooled engine which most of the time is running at a very low % of max power, and is thus hard to blow up, but if your O2 sensor failed the wrong way in the plane at the start of a climb from sea level to FL200, you would quickly be looking at holes in the pistons. It could be done and I am sure has been done in the homebuilt market, but I wonder what the reversion modes are. I wonder if @lesving knows of examples.
Mooney_Driver wrote:
The Antonov 2 also has automixture. I really wonder why no GA plane has it.
I think you still need to decide on lot of leaning modes/engine pseudo-science but for any mode leaning is still a simple command in any GA aircraft, so manufacturers keep it manual (besides that “keeps people/forums/clubhouses busy” and you get a “rich PPL syllabus” )
the best will be just to max GS/FF without any leaning method, but that may hit the engine…
Same question why not have auto-rudder in most touring aircraft? (it can be as simple as coupling aileron/rudder)
I come across these one day, on engine start it seems tricky other than that it will save hit-and-miss on lean and time/fuel
http://flightenhancements.com/auto-lean.html
http://flightenhancements.com/auto-heat.html
My basic strategy in the TB10 is that if the wind is with me then I fly as high as is practical. If it’s against me then as low as practical!
Neither ULPower or Rotax use O2 sensors. Not entirely sure about Rotax, but about 99% They also must run on AVGAS which contains lead. This will destroy O2 sensors pretty fast AFAIK.
The way it works (on ULPower at least, must be similar on Rotax), is pickups measure rpm and throttle position, then use a pre programmed map for injectors and timing. This is the basic mode, and it works without any additional sensors, this it is also the backup mode. The engine runs rich.
Then it uses air inlet temperature and pressure to fine tune the mixture and timing, together with oil temperature and a synch thing to know where each piston is.
The biggest improvement is the mechanical characteristics of a high pressure multipoint fuel injection system. CHT and EGT is not used for anything except monitoring. This is important because it will show if one cylinder gets more or less fuel than the others.
