|
Message
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)
|