# Advanced General Aviation Propeller Study (1971)



## Zipper730 (May 19, 2022)

https://ntrs.nasa.gov/api/citations/19720010354/downloads/19720010354.pdf



This seems to provided some use in terms of calculating propeller thrust.


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## drgondog (May 20, 2022)

Zipper730 said:


> https://ntrs.nasa.gov/api/citations/19720010354/downloads/19720010354.pdf
> 
> 
> 
> This seems to provided some use in terms of calculating propeller thrust.


Good luck with this. Each 

WWII prop varied blade chord 'b' and local blade CL as a function of radius from center to tip. The equations do not contemplate variable Chord and CL as a f(r). Each of the integrations are for the range 0.15R through 1.0R (tip) - so if you have a constant chord/constant CL blade - go for it.


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## Snautzer01 (May 20, 2022)

drgondog said:


> Good luck with this. Each
> 
> WWII prop varied blade chord 'b' and local blade CL as a function of radius from center to tip. The equations do not contemplate variable Chord and CL as a f(r). Each of the integrations are for the range 0.15R through 1.0R (tip) - so if you have a constant chord/constant CL blade - go for it.


Ok now you just talk dirty.... i think. Perhaps...maybe. God i wish there was a colour picture that made it all clear for me.

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## drgondog (May 20, 2022)

Snautzer01 said:


> Ok now you just talk dirty.... i think. Perhaps...maybe. God i wish there was a colour picture that made it all clear for me.


I velly solly.


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## pbehn (May 20, 2022)

Snautzer01 said:


> Ok now you just talk dirty.... i think. Perhaps...maybe. God i wish there was a colour picture that made it all clear for me.


I am starting to understand what is posted, have I been here too long? Should I be worried?

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## Zipper730 (May 20, 2022)

drgondog said:


> WWII prop varied blade chord 'b' and local blade CL as a function of radius from center to tip. The equations do not contemplate variable Chord and CL as a f(r). Each of the integrations are for the range 0.15R through 1.0R (tip) - so if you have a constant chord/constant CL blade - go for it.


That might be a little beyond my paygrade: Regardless, how do you calculate around that?


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## Snautzer01 (May 20, 2022)

pbehn said:


> I am starting to understand what is posted, have I been here too long? Should I be worried?


Yes.

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## Snautzer01 (May 20, 2022)

All sillyness from my side apart, it does give an inside of how good those guys with rulers were.
All those who think that they would make a better aircraft just have to go through this thread. And think again. And then again. I am amazed that so much brainpower was around on all fronts.


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## Zipper730 (May 20, 2022)

Snautzer01 said:


> All sillyness from my side apart, it does give an inside of how good those guys with rulers were.


It actually is. Much of the math I do with excel.

The reason people were better with math in those days is they weren't dependent on calculators since they didn't exist except for slide-rules. They had to actually do it all themselves.

The brain isn't a muscle but some principles apply: The more you do something, the better you get at doing it. We barely do anything, so we're damned near atrophied.

Sadly, I've learned more about math from watching YouTube videos than I have in JHS/HS: That is really sad.


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## drgondog (May 20, 2022)

Zipper730 said:


> That might be a little beyond my paygrade: Regardless, how do you calculate around that?


You find the manufacturers data specific to the propeller.

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## pbehn (May 20, 2022)

drgondog said:


> Good luck with this. Each
> 
> WWII prop varied blade chord 'b' and local blade CL as a function of radius from center to tip. The equations do not contemplate variable Chord and CL as a f(r). Each of the integrations are for the range 0.15R through 1.0R (tip) - so if you have a constant chord/constant CL blade - go for it.


Could it be that the British held off with their CS props until the last minute in 1940 because of the difficulty in doing all these calculations. Were they doing trial and error experiments to find out what actually worked best? Not just for top speed but the whole envelope, climb, dive, acceleration, take off etc? It is a big task without computers.


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## pbehn (May 20, 2022)

Snautzer01 said:


> All sillyness from my side apart, it does give an inside of how good those guys with rulers were.
> All those who think that they would make a better aircraft just have to go through this thread. And think again. And then again. I am amazed that so much brainpower was around on all fronts.


I started off thinking aircraft must be a bit complicated, then I found out the wings and aerofils were complicated. Then the engines and cooling systems were complicated. It turns out even the bloody propeller is so complicated I cant really get my head around it, I must be getting more and more stupid. Or maybe the various ins and outs of a propeller, having to transmit 2,000BHP from zero to 500 MPH at all altitudes and up to 9 G is quite complicated, requiring more than 2 minutes thought to figure out?

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## drgondog (May 21, 2022)

pbehn said:


> I started off thinking aircraft must be a bit complicated, then I found out the wings and aerofils were complicated. Then the engines and cooling systems were complicated. It turns out even the bloody propeller is so complicated I cant really get my head around it, I must be getting more and more stupid. Or maybe the various ins and outs of a propeller, having to transmit 2,000BHP from zero to 500 MPH at all altitudes and up to 9 G is quite complicated, requiring more than 2 minutes thought to figure out?


What is complicated for Piston engine vs jet engine analysis is the multiple unit expressions and conversions required for Drag and Thrust which must be converted to Thrust HP.

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## Zipper730 (May 22, 2022)

drgondog said:


> You find the manufacturers data specific to the propeller.


So, for the F4U's propeller I'd search for the Hamilton Standard 6443A-21, and for the F6F I'd put in Hamilton Standard 6501A-0?


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