I have a Sterba wood prop on a newly purchase RV7A 0-360 1800 HP, at WOT it only makes 2500 rpm.
This seems like it is hurting my top speed performance.
I checked that the the throttle cable it fully wo and that tach is correct.
Should I get a new prop?
Max
I have a Sterba wood prop on a newly purchase RV7A 0-360 1800 HP, at WOT it only makes 2500 rpm.
This seems like it is hurting my top speed performance.
I checked that the the throttle cable it fully wo and that tach is correct.
Should I get a new prop?
Max
Need more details. What flight conditions such as altitude, speed, fuel flow, loading, engine timing verified, etc.
Carl
Assuming you really mean TAS = true air speed, this is slow, even for ‘just’ 2500 rpm.
I’d suggest:
1. Find the make/model of the prop, and confirm with Sterba that it’s recommended for an O-360.
2. Assuming it is, find out why you aren’t making rated power. How are you leaning in cruise?
1) This is not a static test. This in flight
2) Yes TAS =True Air Speed
3) No other reason for not making rated power.
Checked carb mixture and throttle cable have full travel.
WOT at peak power, lean and rich, all tried.
Running smooth all the time , it just reaches 2500 wide open and goes no further.
I have not called Sterba.
(I am not that interest in a keeping a wood prop in the long run)
I am assuming this is a prop issue having rule out fuel air and spark.
Agree or no?
Have you considered shortening the prop slightly ? It is a wood prop after all...
Another 200 RPM is not going to fix your low airspeed problem. Look for drag issues. I assume you have the gear strut and wheel fairings installed and aligned?
Edit: BTW, how are you determining TAS?
I have a Sterba wood prop on a newly purchase RV7A 0-360 1800 HP, at WOT it only makes 2500 rpm.
This seems like it is hurting my top speed performance.
I checked that the the throttle cable it fully wo and that tach is correct.
Should I get a new prop?
Max
SNIPAlso, I don't believe that the Sterba is the most efficient prop out there SNIP.
Larry
I would argue that the over pitched prop is not hurting much at cruise speed, relative to a finer pitch. Most CS prop users dial back the RPM to less than 2500. The lower RPM and higher MAP, especially at lower altitudes, can give a slight economy improvement without sacrificing speed. However, the RPMs keep dropping as you climb, so cruise speed will drop as you get into the higher altitudes.
The problem with too much pitch is poor take off and climb performance. Also, I don't believe that the Sterba is the most efficient prop out there and that could account for your missing performance relative to more modern designs.
FP props require a compromise on the pitch to balance performance atall flight regimes and cruise altitudes.
Larry