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“that things that work in one application (like Rx-7 racing)
just great - may well suck in another application.”
Or not suck enough….
;)
Neilk
From:
Rotary motors in aircraft
[mailto:flyrotary@lancaironline.net] On
Behalf Of Ed Anderson
Sent: March-26-10 7:02 PM
To: Rotary
motors in aircraft
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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