Chris Schmelzer wrote:
: In article ,
: Dylan Smith wrote:

: On 2006-06-09, Montblack Y4-NOT wrote:
: Also, is there a rule of thumb to compare the new 135hp Diesel to 160hp or
: 180hp AvGas engines? On the face of it, it looks like 25-45 fewer hp with
: the Thielert.
:
: The difference is I think the propeller that comes with the Thielert -
: it's constant speed, so all things remaining equal you get more takeoff
: thrust per horsepower.

: And you keep that power to a higher altitude (diesel is TURBO after all)
: versus losing HP the moment you leave the ground (or the moment your
: density altitude goes up)

: On a 100dF day at any altitude, the difference would likely be in favor
: of the thielert (especially with CS prop)

The CS prop helps at takeoff so that the engine can make rated power at
zero airspeed. When moving at cruise speed, it makes no difference if the
engine has a CS prop or a FP prop if the RPM is the same (the FP prop
has the advantage here, because it's lighter).

Cruise power from the O-360 180 HP engine is 75% or 135 HP, obtainable
up to 7500 foot DA. I wouldn't expect to see any performance advantage
at or below this altitude.

The real advantage of the diesel seems to be the vastly reduced fuel flow,
which lets the standard Cherokee tankage get over 9 hours of flying time
(this is the application we're talking about here).
--
Aaron C.