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Bobby,
You are probably aware of this but for some who may
no be so aware- it's all about volumetric
efficiency (VE), and engine can only breathe as much as the volume of the
compression chamber allows it to. In our case 40cu". However you can pack more
in with pressure -Turbo, supercharger and tuned inlet.
The PP does give max breathing capacity but relies
in inlet speed to gain any advantage in raising the pressure from atmospheric,
the tuned inlet will maximize this pressure at a given rpm.
Inlet speed is maximized by the inlet tube diameter
and 44mm is the max speed for max VE to 7,500 rpm. Over 7,500 requires a bigger
inlet but reduces the inlet speed.
I do however accept Bills argument about HP
and performance - for a standard engine.
George ( down under)
fyi
It doesn’t seem to matter what you have
done to the engine…ported, PP, turbo, supercharger.
Boosted engines can make a lot of HP at much lower rpms. A PP should
also.
Bobby
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
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