I thought we might have the same deal here.
Paul Yaw also seems adamant about flowbench testing when modifying
systems
and parts: http://www.yawpower.com/Flow%20Testing.html
I know we run fairly low speeds compared to racers, but everything
counts, I
guess.....
Bill, you say that manifolds usually flow more than the engine can
take, but
what about fuel/air ratio?
Airmass is normally measured only in one spot, before you split the
air into
individual runners. If the flow is not absolutely the same in every
runner
you never get the same ratio for each rotor. Unless you start to
measure
airmass in every runner - too big an installation.
Any ideas for a cheap flowbench? Not necessarly for the finest
differences
for porting or so, just to match intake runners....
Thomas J.
Thomas and Group,
While not discounting Paul's comments about maximum power, (We
should optimize runner lengths on the dyno if possible) the spread
of
WORKABLE lengths will be fairly large. If you inject into the tube
as
opposed to the bellmouth the charge will be adaquately mixed in the
chamber. Paul Yaw is refering to maximum output engines used for
racing. With the use of electronic fuel injection and O2 sensors we
can map a functional fuel/air curve rather quickly. It won't be
perfect
but will be closer than some people ever get carburators!
The fact is that even if both rotors don't put out exactly the same
amount of power the engine will run fine thank you. We really
shouldn't
actually need the MAXIMUM power the engine can put out. In my
case I will be de-rating my engine 40% from what it makes in the
car,
and that will be more than enough. 20B producing 210-250 HP.
Al Gitezen (sorry if I hacked your name Al) has already seen 275 HP
normally aspirated in true dyno tests. The optimum intakes and
exhaust WILL improve our fuel consumption in cruise a lot, which is
what we really need the most. Few of us will be running flat out in
a
Sun 'n Fun 100. We seem to be approaching a workable layout.
Thanks to the efforts of Paul, Jerry, Ed and others we will be able
to fit
things in. The most attention needs to be paid to the airworthyness
of the support systems. There are many rotary powered planes flying
now. The problem is to be sure the cooling, fuel and oil systems are
as bulletproof as we can make them. None of the rotary aircraft that
have had failures had a horsepower "problem". Can we all use more
sure, but it's more important that we keep making what we already
have. End of rant.
Bill Jepson
The goal of my intake has never been max hp. I wanted to have a
simple, light weight, small foot printed intake. The p port was the
answer. I knew that the Leman engine developed 120 per rotor at 6000
rpm. Something less than that would be fine for me.
I no longer want to speculate on how much hp my engine will develop.
We will know eventually. Even if it only developed 180 hp, it would
be the lightest 180 hp engine available for aircraft use. Not bad.
And if it develops 220 hp....if you need it, fine. The Tailwind
certainly can not use more that 200 hp. For those who want to run
higher than 6000 rpm, hugh hp gains will be available from our little
p
ported engine.
I am not yet willing to give up on cool side fuel rail and
injectors.
That is the holy grail of aircraft rotary intake design. Jerry
If all you need is 200 HP and are using a 2.17:1 I don't know why you
are
messing with P-ports.
Paul Lamar
Read again the second sentence of the previous e-mail, I expect my
engine to develop quite a bit more than 200 hp. I don't need it but
it will be fun on climb out. Jerry
The P-port might be a small foot print but it is not cheap. Cheaper than
a turbo no doubt but not as cheap as a side port engine.
It would also not be significantly lighter in weight than a tubing
side port manifold. Some of the configurations we came up with recently will also
fit better with four runners and side ports due to the tighter CL radius
available in the smaller tubes diameters.
Paul Lamar
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