I have been following this thread about the prop modification, and
would like to throw my experience (back) in. I have a ground-adjustable
Warp Drive 3-blade prop that I bought from Dave Leonard, and also have
two wood props.
I was also curious about unloading the prop to get more HP, thus
more speed. Turns out, I have a virtual brick wall max airspeed with
the engine. Here is the data I recorded. It is a little old now, as I
have since overhauled the engine with newer higher compression rotors
and weights, and produce more power. Also, I use the Felix prop all the
time now. The only reason is that the spinner for the Warp prop is 1
inch too small for the cowl, and along with the skinny blades, it looks
too much like an ultralight! I guess my vanity lets me put up with a
little vibration and a little longer takeoff roll.
http://www.weslick.com/Prop%20Charts.htmPerhaps someone can tell me why I don't see any more power (speed) at the higher RPM? I suppose Ed will tell me it is due to my intake?
Bill Eslick
13B NA RD-1A EC-2
650 HRS
I accept that by trimming
the prop I can lighten the load
and gain some HP (though some here seem to think that HP will increase
linearly
with RPM to infinity and I don’t buy that either). But as you alluded to
in
your previous, there's some potential for mistake in trimming any prop
until you are quite sure that you are not HP limited by something other
than
load. And I'm not sure yet. Just a feeling based on the fact that I'm
using a
cut down RX-7 TB that’s maxed out about 1/3 short of fully open. And
honestly I
still havent dug any deeper because the airplane is flying well and
has good performance. But sooner or later I'm going to want to get more
than the 5700RPM I'm currently getting - I want all the performance
that’s
there.