Another consideration, Charlie, might be the ability to produce 75% of 200
horsepower at FL180 or 200, without a blower. You might then be at a very
comfortable burn rate and a wonderful TAS.

Additionally, you should have enough steam to get up there pretty quick.
Might even be able to show Rusty how to get a 3000 FPM rate ;>)

Jack Ford


----- Original Message ----- From: "Charlie England" <ceengland@bellsouth.net>
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
Sent: Wednesday, June 22, 2005 8:10 PM
Subject: [FlyRotary] Re: PP debate was Re: Single PP HP?


 

Lehanover@aol.com wrote:

   

In a message dated 6/22/2005 7:23:37 AM Pacific Daylight Time,
13brv3@bellsouth.net writes:

   While Lynn seems to love PP for racing, I'm not sure I've seen him
   state that he thinks it's the best way to go for aircraft.  How
   about it Lynn, for, or against PP for aircraft use?


Either side port (Bridgeport) or Pport will work just fine for
aircraft use.

This is your lucky day. I have a tube frame with a first Gen body and
a factory Pport engine. It has a Weaver Brothers external pressure
pump, but the front iron is intact, so you could go back to the stock
pump if you like. It has a trans but no rear end. Needs a Speedway or
similar quickchange. A nice trailer is included.

The Pport has shorter intake timing than the "J" Bridgeport engine. It
idles much slower than the Bridgeport engine and has power a bit lower
in the RPM range than the Bridgeport.
It is not difficult to drive around the paddock with a tall first
gear. The Bridgeport is a nasty mess to drive around, and has around 3
HP until it get wound up a bit.The Pport is also still making power
right through 10,000 RPM if that ever comes up. This is a 12-A Pport
with about 300 HP at 10,000.

The home built 13B Pport could be much better. It is just too easy to
build. As I pointed out with the 12A data at 7,500 212 HP and that
engine has the intake tuned to give best power at 9,400 RPM. Those are
real Ohio HP. Not those little California HP used to sell race engines.

A well done 13B Pport with very mild exhaust work should have 230 to
250 continuous at 7,500 RPM. Plan fuel pickups for a 45 degree climb
angle.

If you only need 220 HP then the side port is quick and easy also.

Lynn E. Hanover
     

It's fun to bat around the incredible numbers a rotary is capable of,
but for most of us 160-200 hp at cruise is about the most our airframes
are designed for & can haul fuel for. Even big 4 seaters or very fast
glass can't use more than around 225 continuous hp efficiently (75% of
300 hp). The airframe drag going up means you just waste gas making more
hp than the airframe design speed calls for.

The question I'd like answered is this: What configuration can be made
the most fuel efficient while making hp in this range?

Should it be p-port & 2.1 redrive, p-port & 2.85, side-port & 2.85, etc
etc?

My gut is betting on a small-diameter p-port & 2.85 drive, hoping for
good takeoff performance with a big, fixed pitch prop & keeping fuel
efficiency up turning whatever it takes to cruise at the above power
range. My needs in an RV-7 would be in the 160-180hp (actual cruise
power setting) & someone in an RV-10 would need 190-210 actual cruise hp.

Charlie