Peter has helped me upload this video:
which is one of my tests of the RED A-03 diesel engine in the Sealand DHC-2 Beaver. During this test, I wanted to see what the windmilling and propeller stopping airspeeds were, and what the restart was like. Also of interest was the descent rate windmilling at the specified glide speed, and prop stopped at the specified glide speed. There was about a 500 FPM reduction in descent rate when I stopped the prop. As can be seen, when I increased airpspeed, I got a decent windmill start (I did not use the starter). The propeller is geared, and the diesel engine certainly has higher compression, so a windmill start is a bit more of an effort, as people have mentioned as “engine friction” But, it works. It will be an “abnormal procedure” for this engine installation in the Beaver, but passed the test!
You can notice that there is no propeller control, the prop RPM is controlled by a governor which is controlled by the engine FADEC. We’ll be testing this more, I expect to see some kind of limited propeller control, but that aspect is still part of development.
Did the prop automatically feather in both exercises?
Interesting !
In order to stop injection you had to cut it off (i.e. shut down engine master / FADEC?). It’s notable that it’s happy to restart injecting fuel without using a starter, after being switched back on.
I guess it makes sense that the FADEC doesn’t care if a starter is used or not, it just sees an engine starting to spin and injects fuel.
As for friction, the gear has a multiplicative effect on engine resistance torque, and diesel engines have more resistance than gasoline (they are much better engine brakes), both of which help the prop stop.
JetA/Diesel pistons do not need ignition or sparks, they uses glow plugs not magnetos…in DA40NG, on hot day, you can start engine with all electrics off with one hand turn of the propeller, it won’t run efficiently without FADEC but it will run nonetheless 
In the air, you don’t even need to windmill at higher speed ~ 1200rpm, all you need is pre-heat JetA/Diesel in fuel tank and 1/4 turn of propeller
JetA + air + pressure = start
Avgas + air + spark = start
Ibra wrote:
Diesel or JetA pistons do not need ignition, they uses glow plugs not magnetos…
And even glow plugs are only needed when the engine is very cold.
maxbc wrote:
they are much better engine brakes
Actually, it’s the opposite (in general for traditional engines). A diesel has much more compression. To (start) turning it requires considerably more torque. But, when it is turning at some speed, the engine braking is less than in a gasoline engine. What makes most of the engine braking torque is the air pumping effect through the throttle valve. A gasoline engine will operate at a lower overall pressure. In a diesel there is no throttle valve, thus most of the power used to compress the air is received again as positive power when the piston has passed top dead center. The pumping losses are less in a diesel engine, which also is a part of the reason for higher efficiency, particularly at part load. At WOT there’s no difference in this respect.
Pilot_DAR wrote:
It will be an “abnormal procedure” for this engine installation in the Beaver, but passed the test!
Very interesting. Is there a limit in altitude for which this engine will not be able to start at all?
Ibra wrote:
JetA + air + pressure = start
Not so much the RED engine by the looks of it. It’s a common rail type according to the specs, and will require a computer to run. Meaning it certainly needs electricity
Its more like:
JetA + air + pressure + a running computer = start
Not that it’s a bad thing. A common rail diesel is considered more reliable altogether than older tech.
Ibra wrote:
JetA/Diesel pistons do not need ignition or sparks, they uses glow plugs not magnetos…
Glow plugs are only to warm up the engine when it’s cold. It’s injection that puts fuel in cylinders and compression that ignites (compression-ignition engine).
No electricity → no injection.
Also, if the engine is not running, there is no pressure in the common rail (via the high pressure pump) and injection doesn’t work, or works far worse than it should – you normally have around 2000 bar in the common rail… I believe this (maybe along with the higher required temperature for ignition to happen) makes it harder to start a diesel engine (you need very high pressure from an engine-driven pump).
It seems absolutely impossible that a FADEC injection engine can run without electricity. At least in the DA40-TDI, there are multiple backups for the FADEC for that very reason. There are 2 ECUs, and 4 different powering mechanisms (main alternator excited by regular battery, main alternator with its backup excitation battery, main battery if alternator fails, ECU backup battery if all else fails).
Ibra wrote:
JetA/Diesel pistons do not need ignition or sparks, they uses glow plugs not magnetos
Not the case for the RED A-03, it requires an operating FADEC to run at all. Indeed, control of the electricity is the only way to allow it to run, or shut it down (aside from the firewall fuel valve, which is not good for the fuel pump!).
The FADEC decides on the glow for start, and does its own thing while you hold the starter switch. I have not explored an in flight restart envelope yet, that’s next fall/winter’s testing!
