Friendly thrust competition

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Posted (edited)

For those interested, I bought a large game 550lb scale for 15 dollars at tractor supply and used it to see how much thrust I was making vs my buddy’s chief we just put together. I’m thinking I may have left some rpm on the table, but i pulled 290lbs of thrust competing against a aeronca chief @ 260

Edited by Matthewtanner
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Posted

Am I invited?  ;)

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Posted

And what is your engine /prop/ gears?

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Posted

582/ culver 74” 48/ 2.62 c box

he had lycoming o-145 which is strange, 72” wood prop

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Posted

What RPM were you turning?  on a solid surface? 

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Posted

The Culver 74x48 is quite a bit of prop for a 2.62 gear ratio.  I had a 74x49 on a 582 with a 3,0 C box.  Avid supplied either prop with the 3-1 ratio.  I tried checking for static thrust with a scale like you have, and got about 305 lbs with the culver and did about the same with a 70" 3 blade IVO.  I've heard that even thought they claimed 65 HP on the 0-145, they must have been smaller horses then what the Cont. 65 HP engines used cause they didn't produce near as much power.  Never did compare a 582 with either of them though.  JImChuk

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Posted

Was the pounds required to move the aircraft's dead weight added to the scale number? How much force did it take get each airplane to begin to move?

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Posted

When I did my test pulls, I had the plane sitting on wood planks that were level. I would imagine that anything that would keep the plane from rolling (grass, mud, ect) would lower the indicated reading on the scale. JImChuk

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Posted

When I did my test pulls, I had the plane sitting on wood planks that were level. I would imagine that anything that would keep the plane from rolling (grass, mud, ect) would lower the indicated reading on the scale. JImChuk

I agree,that's why I think you would have to add the static poundage to get it to move to the scale to get a more accurate number of the actual thrust.

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Posted

I think for what it was, it served its purpose as a modality to “hold my beer, pretty sure I make more thrust than you” kind of day 

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Posted

When I did my test pulls, I had the plane sitting on wood planks that were level. I would imagine that anything that would keep the plane from rolling (grass, mud, ect) would lower the indicated reading on the scale. JImChuk

I agree,that's why I think you would have to add the static poundage to get it to move to the scale to get a more accurate number of the actual thrust.

Yep, good read - the static friction of the wheels would have to be added to the total, but you could estimate that by just pulling the aircraft slowly while you read the scale. Then add that number to the static thrust as the scale reads when the prop is wound up.

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Posted

That's why I was gonna do my pull on floats...  because to win competitions I have learned the best way is to get every advantage in my corner.....

 

 Or just cheat.

 

;)

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Posted

I'm old school NASCAR - "if you ain't cheatin, you ain't tryin" :BC:

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Posted

The way he done his test gives a good baseline for static thrust. That is useful in comparing prop length, pitch, ratio, etc. You want an exact test, you'll need more than rolling friction. A controlled climate such as wind, humidity, temps, etc. 90% of all people are going to do it the same way. Good Grief! This isn't NASA.

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Posted

That's why I was gonna do my pull on floats...  because to win competitions I have learned the best way is to get every advantage in my corner.....

 

 Or just cheat.

 

;)

watch your prop.  Water and props don't get along very well for long..

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