("JP" wrote)
[none snipped]
Look the VW Lupo 1.2 TDI article closer. On the right side of the picture
of two Lupo cars you will find a graphic presentation of torque &
horsepower. The blue lines represent a standard production engine model
(61 hp) and the red lines an "optimized" (tuned/chipped or whatever) 90 hp
engine. Left side of the diagram you find the kW and horsepower figures,
at the bottom the rpm and the right side shows the torque readings.

The higher blue curve shows the hp, the lower shows the torque. Now look
e.g. 2500 rpm (drehzahl 1000 U/min) at the bottom, follow the line
straight up until you reach (cross) the upper blue line, then go
horizontally to the left side and look the hp figure. In this example
something like 48 hp.

The highest torque rpm will give you the best fuel economy. That is where
you would like the cruise rpm to be. In case of direct drive arrangement
you get about 55 hp max by using e.g. 3000 rpm engine/prop speed. The
tuned engine version does deliver about 73 hp at the same rpm.

Hopefully this helps you.


SUPER. Thanks JP!

http://www.geocities.com/plane_diesel/index2.html
Little green and red VW Lupos (yellow graph on right side)

If you were plopping that diesel into a 750 lb. RV-3B/Sonex/whatever and you
wanted to cruise 125 - 140 mph with great fuel gph rates, where would you
choose to cross the graph? Both red and blue options.

1800 torque (both)
2500 rpm's (red)?
3000 rpm's (blue)?

Is this in the realm of direct drive possibilities (assuming no vibration
issues, etc) or does this engine NEED a PSRU to take advantage of what the
engine has to offer? (Don't worry about the extra weight - if it needs one,
it needs one! The plane will just have to be a single seater)

How important is torque vs. rpms vs. horsepower in determining where you
want to be on the graph - for engine cruise numbers?

With extra low end torque available (diesel), a known size for the engine
(110+ kg?), a top end cruise speed limit (140 mph), what kind of prop would
you guess at? Big slow turning? Smaller for a higher revving engine?

Let's say today's VW or Toyota diesels can handle some higher rpms - 3000?
4000?

Thanks for helping me put the pieces together in my mind/imagination.


Montblack