X-Mozilla-Keys:                                                                                 
Jeff Spitzer wrote:

At 01:22 PM 8/2/99 -0700, you wrote:

I had a lot of time to think about this on the drive back from
Oshkosh and I too have decided to do away with the waste gate.
I will just limit the throttle opening on takeoff to limit
the boost and consequently the sea level HP. I know the
rotary won't self destruct like a piston engine does if
temporarily over boosted.


I am going to
try for significant boost at 30K altitude. Be real nice
to get above a lot of the weather.

Jeff you mentioned you have decided to use a TO-4. Any recommendations
on wheel diameters or trims?

Yes, but not yet.  I have the info I need to make an educated guess.
That's much better than most.  I have a turbine map for the P trim wheel
which should be about right.  I need to do some figuring to get the right
A/R.  Matching the compressor and turbine is still difficult because there
is no direct speed correlation in the turbine map.

Is it practical to get to 30,000 feet

with a four place 30 foot span 2600 pound gross (KIS TR-4 Cruiser)
and a 13B/TO-4?

I would need a drag polar to give an educated answer.  If the L/D max is
about 15 then the minimum drag would be 173 lb at 2600 lb gross.  If L/D
max is at about 85 MPH indicated then that's 125 ft/s.  True airspeed at
30,000 ft would be 204 ft/s or 139 mph.  Power required would be about 92
hp assuming 70% prop efficiency.  The turbo should be capable of at least
25 in hg MAP at 30K and you probably need less than this for 92 hp.  Sooo,

yes, you could probably get the TR-4 to fly at 30K at something just over
140 mph true.  BTW, the product of wing area and CL would have to be 140 to
do this.  If the wing is over 100 ft^2 then this may be about right.  If
the wing is smaller then you might not make it.  You'll have to fly faster
to avoid stall.  Since this is all based on guesses, my guess is that it
might be close.  So, how do you feel about hanging on the stall at 30K and
139 mph true??

Wing area is 135 square feet. Constant cord. Span is 29 feet. Gross
weight
2300 pounds. Top speed sea level with 210 HP 195 MPH.
Stall speed simple flaps 55 MPH. Cabin width 44 inches cabin height
46 inches. PL

I know the turbo speeds up as altitude increases.
What is the TO-4 turbo RPM max limit? I plan on monitoring it.

The speed limit is based on the compressor wheel.  The TO4B wheels all go
to about 126,000 RPM.

Can you get an Inconel turbine wheel for the TO-4?
or are Inconel tips available  for  TO-4 turbine wheels.

I thought you had some info on this from turbonetics.  I have not been in
touch with them yet so I don't know.

Have you run any numbers on boost verses altitude for such
a beast?

No, not yet.  I'll probably set up a engine model at some pont but its
waaay down on the priority list right now.  I know it will work good enough
for a POC type vehicle and that's my primary goal.

Jeff Spitzer

 
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