----- Original Message -----
Sent: Saturday, July 08, 2006 4:19
PM
Subject: [FlyRotary] Re: Nothing to do
with Rotary Engines, but....
Wendell,
Large electric motors have a couple of parameters that protect them. The
first is instant overloads. These prevent these motors from exceeding a
predetermined amperage( thus HP). If a motor is said to be able to operate at
100 amps then typically the motor instant overload is set for 200 amps. This
allows a motor to RELIABLY start. If IO is exceeded it will shut down the
motor, preventing the good things inside the motor from coming apart. The
second is thermal overloads. This is usually set around 1.3 times the rated
amps. The TO allows you to exceed the amp rating for a period of time until
the thermal capacity of the motor is in danger.
Bill Dube is probably not using either of these to protect the motor on
his bike so he can generate more power but is sacrificing his RELIABILITY. He
is only running the motor for a few seconds so it is much less important than
the use in a plane for example. If you can determine the continuos HP needed
for you to fly at altitude. Then get there before your engine overloads it's
thermal capacity, you can reliably operate at that HP rating. Hope this
helps! Cause HP is HP.
Bob
On Jul 8, 2006, at 11:58 AM, Ed Anderson wrote:
I would hazard a guess that Wendell is probably
alluding to the better energy conversion efficiency of an electric motor
over an internal combustion engine. Assuming the same energy input
(whether in the from of electricity or gasoline) a typical electric motor is
around 50% efficient where as the piston engine is around 25% efficient in
converting input energy to mechanical energy. So for the same energy
input an electric motor should give better conversion efficiency. So
you might get 100 HP out of a motor for a 200HP (electrical energy) input -
whereas to get 100 HP out of a piston engine you would need 400 HP of energy
input (in the form of gasoline) - the rest being "wasted" in form of exhaust
and cooling energy (and some friction).
However, I agree with Jarret 1 HP = 1
HP regardless.
Ed
What I was alluding to is the Fact that gas
engines produce torque during a smaller portion of the 360 degree rotation. An
electric motor on the other hand puts out torque for 360 degrees. Hence when
using an electric motor to drive for instance, a pump; instead of a 4hp
gas engine one can use approximately a 2 hp and get the same pumping
efficiency - like amount of water moved. I think I came across the
formula in an old Grainger catalog but it isn't in the one I have
now. FWIW
Wendell ( I'll disregard the donkey crap statement
for the donkey)