"sebastian" wrote in message
om...
Hi Jan I really appreciate the feedback,

Paragliders are inherently very very slow. A typical paramotor will
have between 15-30hp a very moderate climb rate of 150-300ft/min,
climb speed of 15-20mph, and cruise at about 25-30mph, max speed
~35mph on good day. Part of the reason im setting out to design my
own is that i plan to make use of an electric motor rather that
internal combustion engine. Im using a dc motor that produces maxium
power (15hp) at 48v with 72 rpm/volt =3456rpm. But i may try to run
it at 36v first =2592rpm. One of the nice things about this motor is
its increadibly high and flat torque across the rpm range.

and how do i factor number of blades in the the equation...simpler
would be better but wont more blades allow more thrust per rpm and
smaller diameter and lower tip speed/noise...part of the reason im
going electric is to make it as quiet as possible...

thanks!!!!


You might want to consider that a horsepower is 746 watts.
15 times that is about 11000 watts. At 50 volts, you're going to be drawing
about 220 Amperes.
You're going to need a lot of copper to transmit that current. You're going
to need a lot of battery to provide 220 amps for any significant period of
time. Designing a motor controller at those currents is _NOT_ a trivial
exercise.

A propeller is the least of your worries.

Tim Ward