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Ed,
I hear you. Recalling the presentation Everett
Hatch gave on the Powersport engine, the spent a lot of time to come up with a
PP engine that was tuned for lower RPM operation. That included tweaking port
timing, port/intake diameter, and length. They had something that worked pretty
well.
Mike Wills
Sent: Friday, March 26, 2010 4:02 PM
Subject: [FlyRotary] Re: P-Port performance
One of the things is
your P porting needs to match your operating (real operating)
regime.
Many a person has found
that because we do not have shiftable gears nor most of us constant speed props
that the magic power numbers
At 7500 and higher rpm
may not be attainable. The reason is that you can have an overported
engine that never gets past 5800 rpm. This is because at that rpm the
power may not be sufficient to overcome the prop load due to poor intake
performance at the lower rpm.
I found out almost a
decade ago that things that work in one application (like Rx-7 racing) just
great - may well suck in another application.
From:
Rotary motors in aircraft
[mailto:flyrotary@lancaironline.net] On
Behalf Of Tracy Crook
Sent: Friday, March 26, 2010 1:57
PM
To: Rotary motors in aircraft
Subject: [FlyRotary] Re: P-Port
performance
"I'm looking
forward to hearing about how some of these P-Port engines work
out."
This is the only current flying P-Port
that I know of. Same engine that Paul L. talks about that he Dyno tested
at Mazdatrix. Here are a few clips from Mark Supinski's Mustang II w/
P-port 13B first flight tests. Hard to draw solid conclusions from
first flight especially at that altitude but the max rpm with that small
prop do not look all that good. There may be a lot more potential when
things are worked out.
Tracy
K00V - Meadow
Lakes Airport, Peyton CO
OAT: 50F
Winds: 5kt out of north
Field
Elevation: 6875
Density Altitude: 7680
Mazda 13B rotary, NA with
Peripheral Porting
2.85:1 redrive, standard prop
rotation
Takeoff
roll was 1500 feet max;
Water temps
throughout the climb were a chilly 178F max.
Oil temps were not as
kind, 197F on takeoff, 217F when departing the
pattern, and 241F at 10,000
feet. Oil temps quickly dropped back to
215F on level out,
Maximum rpm was
around
7000 (~2450 prop). Given that our prop is only a 68x68, we
would
expect to be able to get to the electronics limit of
8000
On Fri, Mar 26, 2010 at 12:58 PM, Mike Wills <rv-4mike@cox.net>
wrote:
Your right, my apologies to Bill.
It did come across as pretty gruff. If you've followed previous posts of mine
regarding performance I am very interested in knowing how my airplane stacks up
compared with other RVs, both rotary and Lyc powered. It is hard enough (and
very frustrating) when people post performance numbers at a variety of
altitudes, numbers posted based on IAS or GS without accounting for
environmentals, let alone numbers based on theoretical calculation. How do we
respond to critics of rotary installs without accurate performance
numbers?
I'm sort of in the same position
as Don. I believe based on his previous numbers posted that our performance is
roughly equivalent. I know that my performance is currently less than optimum. I
have too much prop for my current HP. I am limited by my gear ratio. I believe I
am giving up some HP due to a less than ideal intake manifold. Unlike Don, I am
content with current performance (for the
moment).
I'm looking forward to hearing
about how some of these P-Port engines work out. I am considering building up a
new P-port, with RD-1C, and new prop and doing a swap sometime down the road. In
the past week Paul posted a synopsis of the original Powersport install in their
RV-4 and Alan Tolle's RV-3. I'd forgotten how cool those setups were - it was
meeting Alan and Everett Hatch that sold me on the rotary in the first place.
Their Superlight engine was a work of art. My RV-4 is the best performing
airplane I've ever owned. Imagine what it could do if it had another 70HP and
lost 150 pounds (the Powersport RV-4 with Superlight weighed about 860). That
should provide Harmon Rocket performance without having to build another
airplane.
Sent: Thursday,
March 25, 2010 10:25 PM
Subject:
[FlyRotary] Re: Turbo Planning
Your a hard man, however I do agree
with both the Mazdatrix and Powersport results and would expect their
operating at optimum configuration and 100%
VE.
The question in my mind will we all
achieve this in our less than perfect installations - probably
not.
I can't remember exactly but
powersport was running two PP sizes, 38mm or 40mm early version and the
later 44mm. I believe Bill Jepson is awaiting the results of a more
recent 44mm dyno run. That 210hp may be the old
44mm HP numbers - can't remember exactly. Then again it may be the smaller inlet
as they were running 6,000 for take-off RPM. A smaller PP will give greater
inlet speeds reflecting in VE.
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
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