| Charlie,
I can't argue with that logic. But if you tune so that you have enough hp to go fast, then surely you'll have enough to fly slow too. This analogy doesn't work in reverse. You never know when you'll have to blow the doors off a Lycosarus, just because you can.
Mark On Sat, Nov 20, 2010 at 7:41 PM, Charlie England <ceengland@bellsouth.net> wrote:
My thought is to take a somewhat different approach to tuning. My
desire would be to tune for intended cruise rpm. My reasoning is
that just about all homebuilt designs that will run a rotary will
have excess power anyway, so why not tune for max efficiency at the
rpm where the the engine will spend 95%+ of its time? Even more
applicable if a controllable prop is available.
Can anyone see any problem with that logic?
Charlie
On 11/20/2010 10:18 AM, Mark Steitle wrote:
Ed,
OK, that answers my question. By going with 1-7/8" OD pipe
(.049 wall), it would be tuned for about 7800 rpm. Obviously,
this is too high for our purposes. I'll go with 1-5/8 (.063
wall) to shoot for 6700 rpm peak power. This is typically the
rpm I see on ground roll and early climb before I start
adjusting the prop down to a lower rpm to transition to cruise
climb.
Have you used the header designer tool available from Burns
Stainless? You need to know all the timing numbers, rpm, etc.
I may give it a try and see what I come up with. I have a
test p-port housing that I made up to see if the tube could be
welded to the inner liner. So, I can use that with a spare
rotor to verify the EVO and EVC numbers.
Mark
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