Hi Mike,
I am gonna have to let Don tell us his speeds, but he
was at 8000 feet so indicated speed will have to go thru the dreaded
calculation as well in order to find the true airspeed..
:>) since airplanes fly in the air and don’t touch the ground
(except occasionally) every speed you see will be some kind of calculation and
not a “fact”.
Maybe he has a GPS and can fly some kind of
rectangular pattern and find the average (no wind) speed.???
Maybe you can get a copy of Paul’s dyno sheet and take
a look at the horsepower he was producing at the lower rpms I mentioned.
I will bet they are very close to the numbers I mentioned. Mazda used to
claim that the Renesis produced 250 @ 7500, but they have since backed it off
to, I think, 238 @ maybe 8500.
The point I was trying to make about the rotary was
that your HP is based on rpm. All those high HP numbers are all at
really high rpm. Much higher than we run in the plane, unless, like Mark
Steitle, you have a CS prop.
Mark gets (I think I saw him say) 7500 on takeoff and
although I haven’t heard him say, I assume he can get the same in cruise as
well.
Bill B
From: Rotary
motors in aircraft [mailto:flyrotary@lancaironline.net] On Behalf Of Mike Wills
Sent: Thursday, March 25, 2010 9:37
PM
To: Rotary motors in
aircraft
Subject: [FlyRotary]
Re: Turbo Planning
Sorry, not buying it Bill. If
you are going to quote speeds here, quote speeds, not calculated speeds based
on so many variables that the end result is meaningless. That sounds like
something we'd see on the other list, not here. As far as I know, Don's best
reported speed is 174 IAS (and IAS is not all that meaningful either).
Based on performance that Don has actually reported his performance is
roughly equivalent to mine (and I'm both prop and gearing limited). His
performance may have improved since he reported those numbers. In any
case I'd prefer to stick to facts.
Speaking of the other list,
Paul has video of a PP Renesis on a dyno at Mazdatrix cranking out
near 250HP @7500RPM. And he had the dyno sheet to prove it. Powersport claimed
210HP at 2700 prop RPM (their reduction ratio was around 2.2; roughly 6000
engine RPM). I believe they also had dyno data to prove it. I'm anxious
to hear how Mark Stietle's PP 20B performs.
Sent:
Thursday, March 25, 2010 6:25 AM
Subject:
[FlyRotary] Re: Turbo Planning
Mike,
Don didn’t report speed. I took his pitch and
rpm and figured it. That speed at cruise is what he would get with no
slippage or “lift” from the prop. Most of the folks with the Catto are
actually getting higher speeds than would be calculated which indicates that
the prop is producing “lift”, not slippage.
But his engine rpm with that big prop are higher than
any I have seen. With the rotary, rpm = horsepower. If you aint
making the rpm, you aint making the horsepower. It doesn’t seem to
matter what you have done to the engine…ported, PP, turbo, supercharger.
If you look at the dyno charts that are all over the web, you will see that
torque is pretty flat after about 4K, about 150 ft lbs. The horsepower
is around 150 at 6K, maybe 180 at 7K, and 200 at 7.5K. You can get more
horsepower than that, but only if you scream it up to 8K or 8.5K.
All the charts I have seen are within 10 horsepower of each other at all
rpms. The difference in total horsepower is always a higher max
rpm.
We all talk about wanting to cruise at 5800 and make
200 horsepower…it aint happening! Not with the rotary.
Bill B
From: Rotary
motors in aircraft [mailto:flyrotary@lancaironline.net] On Behalf Of Mike Wills
Sent: Thursday, March 25, 2010 1:17
AM
To: Rotary motors in
aircraft
Subject: [FlyRotary]
Re: Turbo Planning
I went back and looked at Don's
previous post. Saw reference to climb performance, RPMs, and temps, but no
speed numbers. Has he previously reported cruise speeds over 200? Last post
from him that I saw with any speed numbers reported 174MPH IAS at
8000. If he's over 200 now, wow those are good
numbers!
Sent:
Wednesday, March 24, 2010 9:15 PM
Subject:
[FlyRotary] Re: Turbo Planning
Those are the best numbers I have seen with anyone
with a Renesis so far. In fact, I have not heard of numbers that good on
any 13B. Don is getting over 200 MPH with a cruise prop and climbing at
over 1400 fpm with it. The only way he is going to do better is either
with an electric CS prop and/or turbo. If he shaves the prop off to say,
74”, he will get a couple hundred more rpm, but will probably lose in total
thrust. Diameter is a big determiner in thrust.
I would like more pictures of Dons intake and
exhaust!
Bill B
From: Rotary
motors in aircraft [mailto:flyrotary@lancaironline.net] On Behalf Of Al Gietzen
Sent: Wednesday, March 24, 2010 3:05
AM
To: Rotary motors in
aircraft
Subject: [FlyRotary]
Re: Turbo Planning
1. When I read your
stats in your first paragraph, the first thought that
comes to mind is
that there is too much prop.
Ditto.
Al
G