effect of a stalled prop?

[topforce]

Was just using motocalc to find an ideal power system to drive a 4 blade 8x8 prop. That prop will absorb alot of power! Anyway, so what if I use it in a lower power set up, and it is stalled most of the time. Will this negatively affect flight performance, or battery duration? I want to use it in an application drawing less than 10 amps and around 10 volts, so probably about 100 watts max input. Too bad I cant find an 8x4 4 blade prop. Any suggestions?

[raptor22]

If it's stalled youre producing little to no thrust from the prop. Really, it isnt the power system but the speed you are flying that decides wheter its stalled or not.

Thare are quite a few people in high performance that just repitch the prop if they really could use an unavailable prop. If you try it be careful to make the modification uniform, though.

--Alex

[steve lewin]

With only 100W input that prop is going to be doing fairly low rpms. As it is stalled at almost all practical speeds it will be producing even less thrust than you might expect at those low rpms.

You don't say what the application is but if it's a scale model why not keep that prop for static judging and use a more practical one for flying ?

BTW the Motocalc help file is very useful. About stalled props it says :
"Indicates that the propeller blades are most likely aerodynamically stalled, and are thus producing far less thrust than predicted (they are basically just beating the air and absorbing a lot of power from the motor). This is typical with high pitch:diameter ratio propellers at low flight speeds. On an in-flight analysis, one can see the speed at which the propeller begins to be effective. This is indicated by red text."

Steve

[topforce]

Application is a flying styro teady bear, wich is pretty much a funked up bearcat. Power would have been a geared razor on 3s2p kokam 340. I have already ditched that power system in favor of a nippy 0808, 3s2p 340, and apc 947 sf prop. Still considering using the 4 blade prop on another plane, perhaps gws p51 with rz2500 power. I picked up the prop same time I got the teady bear, thinking they were perfect for each other. Actually, size of the prop is right for the looks of this little bearcat. Unfortunately, the prop has a gws style mounting hub, and will not fit on the mpjet prop shaft adaptor on the nippy. So, this prop will be saved for gws gearbox applications.