Formulas for calculating static thrust?
 

I'm sure there is a resource out there somewhere that corelates thrust, prop pitch, prop diameter, number of blades, rpm, horsepower, and all up weight. Anybody know where to look or where to begin?

Also how does the speed of the prop tips effect noise? Is there a tip speed threshold that keeps things relatively quiet? How does adding blades impact such a speed/noise ratio? Anyone...anyone...Bueller?

RE: Formulas for calculating static thrust?
 

Pe Reivers has one of the best, do a search..

RE: Formulas for calculating static thrust?
 

Props are quietest when stationary. Everything above that level increases noise exponentially.

RE: Formulas for calculating static thrust?
 

agree to that! The more it spins, the more noise.
In between, Abbot-Boucher provided the formulae, so transatlanticflight could do a search.
All I did was to put it all together to match field experience.

RE: Formulas for calculating static thrust?
 

Per Boucher: Power (watts) = Pitch (ft) * diameter (ft)^4 * (RPM/1000)^3 * constant (k, usually between 0.9 and 1.6 for 2-blade prop)

RE: Formulas for calculating static thrust?
 

There is a chart out here on tip speed verses noise, but my 7 year old computer just died and took 7 years of links with it.:( I think I remember you want to keep prop tip speed below 400 mph, above that the noise really goes up.

RE: Formulas for calculating static thrust?
 

That is right. You want to keep the tip speed below 0.6 Mach.

RE: Formulas for calculating static thrust?
 

Here is the prop chart

RE: Formulas for calculating static thrust?
 

Gentlemen,

Thanks to you all...good information. Even tired old man's comment - I appreciate nice dry wit. Sorry, I'm just tuning back in - I was away from web access for a bit. I will do a search and look at both Pe's charts and the info on Boucher' formula.

Regarding the formula posted, what does the ^ mean - raise to the power of?

Also, how does the constant play into it all? Is there a different constant for 3 and 4 blade props? If so how are they derived?

Lastly, the relationship of all up weight to power in watts? What is the ideal ratio? Or better what is the minimum to sustain flight? Though I'm sure this depends on the lift of the wing as well. Maybe then power to wing loading?

Rick

RE: Formulas for calculating static thrust?
 

Rick,

go here: http://www.mvvs.nl/prop-power-calculator.xls . Everything will be clear. This spreadsheet contains all the constants for popular propellers and corrects for altitude.

For the amount of "power" required, a short calculation from the electric plane world a good place to start. Basically it states that a plane needs 50 watts/pound to ROG and fly like a trainer, 60 W/lb for basic aerobatics, 70 W/lb for aggressive aerobatics, 80 W/lb for pylon racers, 100 W/lb for pattern, etc. One HP is 746 Watts.

RE: Formulas for calculating static thrust?
 

Yes
The constant covers all fixed values derived from prop shape, and prop disc coverage. So yes, three bladed props are covered, so are shortened props,
Also i.e. are propellers in water (raise barometric pressure to get the right fluid density) etc. etc.