Thomas Borchert wrote:

It was my (mis?)understanding that a diesel is, HP/lb, heavier than a
standard aircraft engine, especially when getting into the higher
(over 250) HP models. Correct?

Not necessarily, but the big Thielert at 350 HP is heavier than an
IO-520/550. 60 pounds or so.

On the other hand, the diesel airplane will typically require less fuel in
order to complete the same mission as the avgas airplane. The saved fuel
weight can offset some or all of the weight penalty of the heavier engine.

Of course this does not apply when topping off the tanks - but in that
case, the diesel airplane gains a lot in range.

So it looks like there is a free lunch after all - at least when not
counting the acquisition costs! :-)


Greetings,
Markus