Earthstar Forums

Hi Bruce..
Would really like to have your take on how to explain the relationship or difference between Power and Thrust.
Thanks
RMM

Sorry to but in but power is what the engine or motor is producing via torque and rotational speed and thrust is related to the capacity of the propellor to move air, small prop small thrust at same power,large prop large thrust same power. A Cessna 172 has 350 lb static thrust small prop, a Robinson R 22 big prop over 3000 lb of thrust. Same engine.
Happy Flying
Mark

Sent from my iPhone

Power = Thrust (F) times Velocity

P= F x V

Please note that thrust diminishes greatly with speed (Velocity) on piston
engines with propellers, as power remains practically constant

I have tested about 8 different ULs with 503, 582, HKS engines and
different props tied from the tail with a weight scale to measure static
thrust

I have gotten figures ranging from 3.5 to 4.5 lbs of thrust per nominal Hp
(Actual power ranging probably from 85% to 90% of nominal power due to
altitude, temperature, barometric pressure and humidity )

According to the attachments a C-172 should be producing around 211 Kg =
464 lbs of thrust at the altitude, temperature , barometric pressure, that
those tests were conducted

Static thrust tests <file:///Users/jim2107873540/Downloads/M0755.pdf>

Helicopter thrust must be measured under 2 very different conditions:

A.- In ground effect (HIGE)
B.- Out of ground effect (HOGE)

Those big rotors give it a much higher efficiency for take off

Say, 10-12 lbs per Hp in HOGE and 16-20 lbs per Hp of thrust for HIGE




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Great example Mark! How do I get one of those Robinson props on my TGull? .....still laughing.

Seems to me that the early ones were called the “Laughing Gull” - Maybe they had that Robinson prop…



Sorry, just had to do it…

Robertson props are to expensive.
And they would hit the tail boom.
Happy Flying
Mark

Sent from my iPhone

laughing gulls the best ever... doves and lapwings doing a major flyby here today

(saw a guy kick off a motor discussion on a physics forum, with a 100Kg magnet and 100kg of copper wire, and then what... very signifnificant discussion)