Tom Smythe wrote:

Hi,

I'm the guy that was going to drop a 3 rotor into a Moose a while ago

but, have been having second

thoughts as I just don't think the performance is what it could be (I

also looked at the Aerocomp

birds but, again, think performance is lacking...).

So, I've undertaken designing a nice little six place plane of my own.

Probably a composite bird

as I believe composites allow much more freedom and an aerodynamically

clean airframe overall. To

that end, I still would like a powerplant in the 400HP range (like the

Moose had with the latest

Russian radial but not the fuel hungry turbine on the Aerocomp models).

Given the ability of the rotary to handle quite a bit of boost, I've

come up with the table below

(standard day):

                           2-Rotor     3-Rotor
                           13B         20B
 NA HP @ 6,500 RPM             195        290
 (guestimated)
 Fuel Flow (lbs/min)         1.4625      2.175
 Air Flow (ft^3/min) (59*   285.1875    424.125
 day)
 (air flow volume changes
 with temp, but mass
 stays the same and thus
 the MAP)
 400 HP Fuel Flow            3.0000      3.0000
 (lbs/min)
 400 HP Air Flow               585        585
 (ft^3/min)
 MAP @ Sea Level              2.05        1.38
 MAP @ 10,000'                3.02        2.03
 MAP @ 15,000'                3.64        2.45
 MAP @ 20,000'                4.46        3.00
 400 HP Air Flow               45          45
 (lbs/min)
 Recommended Turbocharger      T61        T61
 100% Power Ceiling          17,000'      26,000

The T61 is operating near the surge limit to achieve the HP required on

the 13B. However, on the

20B, it's actually loafing along fairly nicely. Assuming the above

numbers are correct, I'll be

planning the airframe around the 20B. Otherwise, it's back to the

drawing board.

As an FYI, the airframe is a high wing design with fixed gear and a

gross weight at 4,400 lbs

(give or take...) and usefull load of 1,800 lbs (600 lbs fuel). The

initial design was created in

AirplanePDQ and is being evaluated in X-Plane (5.61).

Thanks,

tom

Barnhart wrote:

Tom,

I'm the guy putting the 20bt in a Murphy Super Rebel. No second thoughts
here at all. Just want to get it flying.

 You are right the Moose could be a little improved in the performance area.
All of those rivets, float and ski brackets, struts, and big tires add up
quick in drag.

Where are you going to find a PRSU for 400 hp? Any idea on hp needed to
cruise on?

Are you thinking about a STOL or fast wing? At least 150 gallon tanks for
fuel. You won't get too far with only 100 gallons of fuel. I wish I had more
than the 80 gallons I have now.  Should have an empty weight of 1700lbs,
with a gross of 3200 lbs.  I'll have a useful of 1500 lbs on proven
components based on turboed 300 hp. The 20bt will be hardly working at
cruise, and not working hard on takeoff.

Barny
Super Rebel 2500, Mean Green Drag Queen.

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