ORIGINAL: adam_one
ORIGINAL: dick Hanson
OK-- try this:
I did a lot of testing with electric motor and a thrust stand andfound this situation to be very repeatable :
when a given amount of energy (watts ) were absorbed by the motor --the thrust was always -always - almost identical
In actual practice with larger models the results were very hard to qualify. (and I used up to, including, my 160 cc , 40 lb EXTRA
Why?
each different prop put the prop at a different rpm which was at a different point in the power curve of the engine .
the actual torque reaction at stationary hover tho -was the same -IRRESPECTIVE of prop
not surprising as the work (load)was the same .
also no matter how hard the engine appears to be "working"-- the stationary hover will require the same amount of "WORK" if the weight to be hovered is the same.
This is basic physics
Ponder this:
A small prop requires more power (watts) to produce the same thrust as a larger one.
For instance, a 12x7 Aeronaut prop at 6000 RPM takes about 85W to produce 27 oz of thrust.
To produce the same thrust a 6x5 prop needs 18000 RPM and takes about 195W.
Another detail is that power is not energy.
Electric Power = V*I (watts)
Electric Energy = Power*time (Wh) or (Joule - Ws)
OOOOK---
Now--do you ever fly the so called 3D stuf - have you ever tested the various props used for THAT type flying .
and - what is the nit picking about Joules for?
Are you simply bored?