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Neilk,
I used to think engines sucked, but now they say
they don't suck.
Just the negative pressure in the compression
chamber after the exhaust is expelled, is filled by the outside pressure
rushing in to equal the pressures.
If you can get it to rush in faster with a
smaller diameter inlet(without restricting the flow) you will get greater
volumetric efficiency - as the speed of the flow tends to pack it in
better.
That's how I see it anyway.
George ( down under)
“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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