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At 11:26 AM 6/2/2006, Fred Lamkey wrote:
I would like to have better climb and takeoff performance. Would
you recommend having the prop changed,
Yes, that's really your only option, other than converting to a C85
(which require a prop change also).
is 73 too much for the C75,
No. At the slower RPMs of the 75, a longer prop is beneficial.
what pitch (and length would be recommended),
Stay with the 73" length. First, figure out exactly where you
stand. Measure the actual diameter of the prop. Get a tach checker
and figure out your actual static RPM. Do this on a day that is as
close to standard as possible, and as close to sea level as
possible. Allowable static RPM range for that prop and engine is
1950 to 2100. For better climb at the expense of cruise speed,
repitch the prop to obtain a static RPM close to the 2100 RPM
limit. Absent any facts, I'd suggest a 2 " pitch change down. (The
actual diameter and pitch of your prop may differ from the number
stamped on it, but a 2" relative change will get you pointed in the
right direction.)
how much would it cost to have it changed, long would it take and
finally, who does this?
Probably around $200. It doesn't take long in hours, but getting to
the head of the queue and shipping times can add variability. Any
well equipped prop shop can do it. You may want to have the prop
overhauled at the same time. Note, there is a limit to the number of
times a prop can be repitched, and some props that have been worked
on in the past and may be at limits that prevent further changes or overhauls.
John Cooper, A&P
Skyport Services
PO Box 249
4996 Delaware Tnpk
Rensselaerville, NY 12147
518 797-3064
Fax 518 797-3865
www.skyportservices.net
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