OK, since Tracy keeps
whining about my prop, let's talk about this.
First, for those who
don't know, I have a 68", 3 blade Warp Drive prop. It's currently not
tapered, but Warp can taper the blades to get better top end, without
sacrificing climb. They requested that I wait until I could give them
pitch, rpm, and speed numbers before they tapered the tips, since they needed
to make sure they didn't take off too much blade area. I have not done
this yet, since I have only started flying the non-turbo (final)
configuration.
Here are the
facts:
- The plane is an
RV-3. The "standard" prop length is 68", which gives 7 inches of
clearance in two point attitude.
- I have a 2.17 RD-1B
drive, and I can't go to the 2.85 because of the left thrust built into my
mount (at my request).
- The 13B engine was
build by Bruce T, with 9.7 rotors, and street porting. It is capable of
running strong to 7500, and I would like that to be my top rpm at WOT at sea
level. I am not afraid to run 7000 rpm continuous.
- The plane is a toy, and
performance is more important than economy. I would like to be able to
run up to the 210 VNE easily, while maintaining spectacular climb
performance.
- I prefer adjustable
pitch props, even if only ground adjustable.
- I'm not afraid to run
an IVO prop.
The way I look at this,
to get the power I want from this engine, I have to run high rpms. The
only way I can do that is to stay with the 68" prop length. Warp
required me to run a 3 blade for the power I expected, so a 2 blade was not an
option. I didn't ask IVO about this, but they may require a 3 blade
also. I came so very close to getting an IVO, just so I could use the
in-flight adjustable prop. That may be the key to getting the best climb
and cruise performance. Even now, I'm seriously thinking of ordering
one, and trying to do the "cuff" thing that Tracy is doing if top speed is an
issue. Funny thing is that some folks seem to have a problem with this,
and some don't.
OK, there you go.
You'll notice that I really don't want to use a fixed pitch wood prop, unless
that's clearly the best choice. Any recommendations will be very
welcome.
Cheers,
Rusty (this is going to
cost me)