While there is no
question that P porting will provide more power and its reputation for poor
idle (whether deserved or not) at low rpm does not affect its
suitability for our use, I think there are other considerations. IF you
can buy a properly make P port or have the knowledge and machinery to do it
yourself correctly , it might be well worth doing. However, I have found
that approaches designed from max power out put at high rpm may not
always be compatible with longevity or reliability, factors of most importance
in aircraft so you need to check into that. I tried a Rotary Racing
manifold early on and while it was probably great for a rotary turning 9000+
rpm, it really performed poorly at 5000-6000 rpm. Once I replaced it
with an intake design from my engines actual operating range power improved
considerably.
I, for one, found
that building my own aircraft and converting a pretty much stock 13B for
aircraft use was about all I could handle back almost 15 years ago. With
the knowledge on this list that is now pretty much a straight forward thing -
but still a lot of work. I fly a 13B rotated 90 deg so that the Plugs
are UP so I am certainly not against experimenting with the rotary engine.
But, I have know of
several folks who tried P porting own their own and ran into a much
bigger challenge than they had anticipated. For one thing, it turns out
the best P port parameters for aircraft use are different than that used by
the all-out racers. A second thing is some folks have run into
challenges in sealing the coolant galley after cutting the hole in the rotor
housing, the interface to the steel sheath inside the rotor housing also needs
to be done correctly as well. All challenges that can be overcome but
require time and $$.
So can it be done?
certainly it can be done. Is it the best approach for what you have in mind
only you can decide that. But, the more different you are from the
stock engine the more benefit and the more disadvantage you will
encounter. While some early experimenters Everret Hatch comes to mind
(whose project was sold to PowerSport) who put one in an Rv-4 that Allen Tole?
Flew to a screaming take off and climb out at Sun & Fun before blowing a
bearing in the PSRU (NOT a RWS PSRU)- showed some initial promises for the P
port in aircraft But, I have not seen any follow up or growth in that area
for aircraft.
The real question is
the benefit worth the extra effort I think many have decided the stock
engine perhaps with turbo is the way to go. I think the P port is an
elegant approach to getting more power but, more of a challenge than Im
interested in and it would not do a thing for me given the way I fly.
Naturally the flight environment and needs of others will vary from my
requirements.
Bill Jepson already
mentioned the simplification of the intake (at least space wise) of the
intake. It is also the lightest modification you can make to produce
that kind of power as it should end up weighing a bit less than a stock
13B and certainly less than a 13B with a Turbo.
So if you are up to
the challenge go for it, but be aware it is a
challenge.
Best
Regards
Ed
From:
Rotary motors in aircraft
[mailto:flyrotary@lancaironline.net] On
Behalf Of WRJJRS@aol.com
Sent: Sunday, September 06, 2009 3:07
PM
To: Rotary motors in aircraft
Subject: [FlyRotary] Re: Three or
two?
Sorry to be
contrary, but in my opinion the ONLY way to go for a flying rotary is P-port.
All of the original Power Sport engines (the Everette Hatch P.S.) ran P-ports.
The manifolding for a P-port engine is vastly easier. In fact Hatch and Steve
Beckham built several engines with P-ports that even ran reverse rotation so
they could get proper propeller rotation with some gearboxes. You can even
P-port an Renesis and it still works. The reason that Mazda isn't P-porting
their race cars has nothing to do with if P-porting is better, it is racing
organizations requirements. The reason for the side port Renesis is for
emissions and low RPM fuel economy. Those are areas that are only important in
a CAR. The typical aircraft runs 50% to 90% ALL THE TIME and P-ports are much
better at mid to high RPMS. The Mazda Le Mans winning engine used P-ports and
they were running with a fuel economy formula. (the fuel was limited) For high
output P-ports just work better.
Gonzalo,
A lot of people
talk about peripheral porting rotaries but nobody is doing it with a rotary
that they plan to fly behind. If it was such a good thing, Mazda would
be P-Porting their cars. Instead they are going away even from the
peripheral port for the exhaust with the Renesis.
If 200 HP will do
it for you the Renesis is the way to go. This process of putting an
alternative engine in a plane is hard enough without violating the
KISS
principle.
Put in a Renesis,
no turbo, no P-Port.
Bill
B
From:
Rotary motors in
aircraft [mailto:flyrotary@lancaironline.net]
On Behalf Of George
Lendich
Sent: Sunday,
August 23, 2009 5:57 PM
To:
Rotary motors in
aircraft
Subject: [FlyRotary] Re: Three or
two?
I don't know if
the Renesis has a turbo version, I didn't think it did. All turbo 13B's
require low compression rotors.
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