Thorp Air Command - T18.net

Gentlemen,
Since my excellent landing at the KY. fish fry fly in I've made some progress on the repair. New skins on the cowl in front of the wind-screen, gear legs straightened, welded, & heated. I am now looking for some info. on prop. & pitch.. I asked Howard Henderson, since he made the prop., what pitch he had built into it. His answer was, gosh , Mike , I can't remember sometimes what I did yesterday let alone what I did 35 years ago.

Anyway that

Well, Mike - If I were in yer shooz, I would stock the beer fridge, relocate it within arms reach of your favorite chair, have a pizza ready, your credit card out ora a cheque ready, a pen and paper handy, make sure your phone has a full charge and is glued/taped to your ear and then call Mike Demuth of Aymar Demuth Propellers - You'll have all the answers and a new prop on order within a few hours. Mike takes the time to understand everything about your plane/motor/mission/location and will prop you out well.

Of course there is always a month of being a hooker or the bank for a loan on a Hartzell or MT constant speed....

I agree with Frase. Mike Demuth will talk your ear off. But he really knows what he is talking about.
He also produces the best prop for the money. Mine is a 68 x 75 from him.
I have a 160hp lyc

With the standard landing gear, a 68x70 prop works pretty well, but you won't get 2700 RPM on takeoff. That is for the 150 P Lyc.

That prop will be a 68x72 demuth. My bird weighed in at 880 dry, it has 0320 e2d, very happy with it.Dan

There is a 68x72 AD prop for sale on VAF for $350

AD prop for $350.00 $$$ is a steal, providing it has 2 blades ! Even with the shipping hoping it is in good shape it is a good deal !

RB

Unless there's a different prop ad that I missed, the one for $350 is an Ed Sterba prop removed from an RV6A.

Just going by Bob Mo's info ?

RB

My first mistake of the year. I must have ment 'ED' prop.

Bob MO

I run an Ed Sterba 68X72 prop on 150 hp O-320-E2D. 2350 RPM static, and hits 2700 RPM at full throttle and 200 MPH. I borrowed an AD 68X72 prop from a friend to compare, and numbers were about the same. The AD prop seemed to have a little longer takeoff run to me. I am very happy so far with the sterba prop. It seems to be much stronger construction.

Jeff,
That's good to know. I thought I made a mistake, but I was wrong.

It might be nice to have a prop list, for reference, where we can see what other Thorps are running.

Prop Brand, Length, Pitch,T/S18, HP, weight, performance, RPMs, Satisfaction, price, etc.

Bob MO

I will start:

N18GR. Catto prop. 68X74. Pretty stock 1978 T-18 (refurbished in 2009-10) w/O-360 and 10:1 pistons, mty weight 915#. @2900 rpm (give or take a bit, my electronic tach seems to stray some) it will do 210-215 MPH, S&L at about 2000 ft ASL. With one soul on board and about 3/4 tank of gas, it will get off the ground in about 700 feet or so, and then when reaching about 110-15 MPH will climb at 2000 + FPM. I usually pull the throttle a fair amount for cruise at 2600 RPM, doing typically 185 MPH true at 8 gal/hr (leaned out).
Dave M

MLM (N886Y) arrived with a Felix 69x73 on an O360 de-rated to 168 HP. Empty weight was 950 or so.

The Fraser-Man can fill us in on the performance.

If memory serves for Dick's airplane, WOT at 8500 MSL, 192 MPH True. Econo cruise at 2350 RPM was 155 MPH and regular cruise at 2450 to 2500 was about 165-170 MPH true. I think with a good/better prop those numbers will go up a tad.