wrote in
:

A non-turbo Comanche-260 will pretty much hold 500 fpm up to
higher than you can fly without oxygen. Unless you go full-tilt into
high altitude with O2, etc, a Comanche-260 seems to outperform a turbo
Arrow in just about every respect. It also doesn't have the drawback
of the extremely abused TIO-360 Continental in the mid 70's Turbo
Arrow. My mechanic just bought one of those, and all I can say is
that he's comfortable with the twitchiness of that engine. Something
to be said for simplicity... either normally-aspirated, big-bore, or
at most a turbo-normalized engine.

A friend of mine used to have a partnership in a Comanche 260. And
yes... I fly a turbo-Arrow III. One a number of trips we would wind up
chasing each other (both coming back from the same meeting, but couldn't
plane-pool up there; or I would take him up to pick up his plane when
another partner had left it somewhere due to weather or repairs). It
was always a fascinating exercise in flight planning to see which plane
would chase which.

The Comanche clearly was faster at low altitude. Down around 8K or less
the turbo Arrow flies pretty much like a straight Arrow - figure 145
knots or so. And initially the Comanche has more "get up and go" climb
performance from sea level.

OTOH, at high altitudes (low flight levels) my Arrow will true out
around 175 knots (it has the Merlyn wastegate) and burn a LOT less fuel
(GAMIjectors). Also, at those high altitudes, my ability to get more
direct routing is a lot better. [BTW, both the GAMI and the Merlyn
greatly reduce both the "abuse" and the "twichiness" of the turbo
Arrow.]

Objectively, it was about half and half who one. Long trips,
particularly with a tailwind, and I would virtually always win. Short
hops of 150 nm or so and the Comanche would always win. Fun...

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James M. Knox
TriSoft ph 512-385-0316
1109-A Shady Lane fax 512-366-4331
Austin, Tx 78721
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