In reference to the prop repitching discussion, Pete asked:
> Just curious...what does that do to cruise speed at what RPM's?
Pete,
My observation on typical Ercoupe models is that they have about 4% slippage
from the theoretical speed they'd get from the pitch of the prop.
i.e. airspeed would, in theory = Pitch (in inches) * rpm * 60
Convert that to statute mph by dividing by (12*5280)
Then, multiply that times .96 to get expected true airspeed at low altitude.
Examples:
Expected Airspeed
Theoretical airspeed
Prop pitch in inches
rpm
100.4
104.5
46
2400
104.5
108.9
46
2500
107.7
112.2
46
2575
104.7
109.1
48
2400
109.1
113.6
48
2500
112.4
117.0
48
2575
109.1
113.6
50
2400
113.6
118.4
50
2500
117.0
121.9
50
2575
(note: the numbers I've seen tested bear fairly close resemblance to these
table values)
Ed
Ed Burkhead
http://edburkhead.com East Peoria, Illinois
ed -at- edburkhead???.com (change -at- to @ and remove "???")
