Ed,
I will measure next time I am at the airport. But I know I will
be closer to Sam’s numbers. My prop looks exactly like his.
This makes me feel a little better, as I was wondering why my
static was so low compared to other’s numbers.
I still think I will get airborne again, and actually check out
what my dynamic max RPM is before I make any changes.
Chris
From: Rotary motors in
aircraft [mailto:flyrotary@lancaironline.net] On Behalf Of Ed Anderson
Sent: Monday, October 04, 2010 6:58 AM
To: Rotary motors in aircraft
Subject: [FlyRotary] Re: Sam Hodges Prop area Comparison
With Sam's
original prop, he got around 5000 rpm max static. May have been as high
as 5100 but ranged around 4800-5000 rpm. When He put my 74x88 Performance
Prop on he got as high as 6100 rpm one time but each time got at least 6000
rpm.
Measure your
chord at its widest point - mine is 5 1/2", Sam's was around 8" - not
the whole story on a prop, but can be an indication of whether your prop is
close to one end of the spectrum or the other
Sent: Sunday, October 03,
2010 9:37 PM
Subject: [FlyRotary] Re: Sam
Hodges Prop area Comparison
Ed,
I have the same Catto prop and mine is marked 76x88. I
didn’t get more than 5000 RPM max static either. To be honest, I didn’t
look at the max RPM while airborne, I was too busy looking at the temp, and I
pulled the power back as soon as I could. I hope to fly again with the
new radiator in a few weeks, and should be able to get new data. What
were Sam’s numbers Max static with the CATTO and with your prop?
Thanks,
Chris
From: Rotary motors in
aircraft [mailto:flyrotary@lancaironline.net] On Behalf Of Ed Anderson
Sent: Sunday, October 03, 2010 10:46 AM
To: Rotary motors in aircraft
Subject: [FlyRotary] Sam Hodges Prop area Comparison
Just doing a
rough back of the envelope calculation comparing Sam Hodges prop (8"
cord) to my prop (5 1/2" cord) and assuming the two props blade profiles
were similar, Sam's prop would have approx 45% more prop area trying to push
the air back than my prop. Small wonder his engine was groaning trying to
spin it up to 6000 rpm.