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diverdon
06-01-2009, 08:26 AM
Hello everyone ,

I have always wondered about this .. Can you mix the Bell from one motor ... say a 2409-18with the windings (Insides) of another motor like the 2410-09 ?? I wonder .. Well I have tried it got it together .. They both have the same # of segments 13 I think ...

In the original motors the number of magnets to winding segments doesn't match .. just a For your info ..

Oh well I have a test stand and a Whatt Meter I will try this thing tomorrow ... Bedtime now 3:30 here .. Goodnite , Don

CHELLIE
06-01-2009, 08:45 AM
some times it will work and not others, you are changing the timing and kv of the motor, if its not the exact same as what you took off, have fun, Chellie

diverdon
06-02-2009, 12:27 AM
some times it will work and not others, you are changing the timing and kv of the motor, if its not the exact same as what you took off, have fun, Chellie

Your right Chellie .. it didn't work .. One more question ... If you have the watts that the whatt meter has given you as peak watts is there a way to tell how much thrust that there is there ??

Just a thought .. I have a test stand with a didigal scale but it seems to weigh off .. Like it is weighing heavy .. Thanks for any help I can Get ... Don j

flydiver
06-02-2009, 03:38 AM
The # of stator poles (where the wire is wound) and the # of magnets need to be a certain relationship. It's a bit complex and there are charts if you really want to dig deeper.

I don't have a thrust stand but there certainly a relationship between watts and thrust. More watts > more thrust.
But you have the complexity of small props spinning fast vs. large props spinning slow. You can have similar watts, and thrust for that matter, but you get an entirely different flying experience.

Larry3215
06-02-2009, 06:15 AM
You can get huge thrust numbers - at very slow speeds OR you can get small thrust numbers at very fast speeds - for the same exact number of watts.

Thrust and speed go hand in hand. It takes more power to go faster and it takes more power to pull harder.

For a given amount of power input, you can raise one but the other will go down unless you add more power.

So, there isnt a direct relationship between power and thrust. You cant say "I will get X amount of thrust if I have Y amount of power". It will depend on the rpm and the prop diameter and the prop pitch. They all work together.

Generally speaking, if you increase the power by a certain amount the thrust and speed combined will increase by a similar amount - assuming your not pushing the motor into an in-efficient power band.

By the way, thrust goes UP or DOWN as the 4th power of the diameter of the prop. So if you double the diameter of a prop (at the same rpm and pitch) you will get 16 times the thrust. It will cost you 16 times as much power to do that.

Thrust 'only' goes up as the 3rd power of rpm. So if you double the rpm (keeping the diameter the same) you get 8 times the thrust. That will 'only' cost you 8 times as much power. :)

So if thrust is what your after - as in 3D flying or a draggy slow flyer - the diameter of the prop is far more important than rpm its turning as far as thrust production.