Engine thrust

[asra]

If anyone out there knows the static thrust of any engine nominally rated at 100 HP or more, I would Like to know. The only figure I have seen so far is the RAF claim 570 - 600 lb. Has anyone verified that number?Daryl Patterson

[asra]

Daryl: Any engine feeding a common propeller will develop around 2,5 Kg of static thrust for HP, as rule of tumb.You will obtain aprox 250 Kg or 550 pounds of thrust with your engine.Bad propellers (Like Ivo Prop) will give 10% less and the very good ones (Prince P-Tip) 10% more power.If you include a spinner (A big one) you will obtain 50 RPM more for free.Keep'em spinning.Edgardo MaffiaBuenos Aires - Argentina

[asra]

Thanks Edgardo. Do you or anyone else out there have any knoweledge about the effects of prop Diameter, pitch or speed on the thrust produced. Generally, a bigger diameter and slower turning propeller should be better, but I'm looking for more specific information than that.Daryl Patterson

[birdy]

"Bad propellers (Like Ivo Prop) "Could you elaborate on that please.Ignorance is bliss............but only till you realise you were.Ingratitude stinks.......be generous carefully.

[asra]

I may have what you want Daryl, it's a graph relating prop static thrust to HP per square foot of prop disc area. Unfortunately I'm not smart enough to be able to post it for you, but I will give you some details.Both the X & Y axes are logarithmic, so what is shown as a straight line would be a curve if drawn linear, if you get some log/log graph paper the points I give should be a straight line.1 HP/square' = 8.2 lbs thrust/HP2 " = 6.53 " = 5.64 " = 5.15 " = 4.86 " = 4.57 " = 4.28 " = 4.059 " = 3.910 " = 3.8The thrust from a prop goes up hyperbolically until the tip goes transonic, then all you get is a lot of noise, I think I recently posted somewhere else the magic number 201,655. If you divide that by either the prop rpm or the prop diameter in inches you will get the limit on what the other can be.I hope that helps.John EvansThink logically and do things well, think laterally and do things better.

[asra]

Thanks John, that should be a big help.Daryl Patterson

[asra]

I finally found some log log graph paper.Daryl Patterson

[asra]

If, unlike me, you are clever enough to post your graph here others may find it usefull.John EvansThink logically and do things well, think laterally and do things better.