Propellors vs Rotors

BTW, a 700 rpm rotor is pretty small and may be really inefficient--even by
helicopter standards!

The Schweizer 300 (formerly Hughes 269C) has a rotor rpm power on of 442 to
471 rpm. Power off range is 390 to 504 rpm. Esceed these limits and you
are quite likely to break something.

The Schweizer has 190 hp and gross weight is 2050 lbs.

Colin

Hi Colin,

I cant remember what the max rotor rpm on the R22 Beta is although
I have a few hours in them. I just make sure that both guages
stay in the green arc and that little light and the annoying horn
don't come on ;-).

Don W.

COLIN LAMB wrote:

BTW, a 700 rpm rotor is pretty small and may be really inefficient--even by
helicopter standards!


The Schweizer 300 (formerly Hughes 269C) has a rotor rpm power on of 442 to
471 rpm. Power off range is 390 to 504 rpm. Esceed these limits and you
are quite likely to break something.

The Schweizer has 190 hp and gross weight is 2050 lbs.

Colin

Hi Don:

Yes, we are taught that if the rpm gets too low, we are dead. If the rpm
gets too high, the gearbox is blown. Keep the rotor in the green or you may
not walk away - and you have 1.75 seconds to drop the collective when the
engine quits in the Schweizer - even less in the Robinson.

But, where else can you pay $200 per hour to move one foot away from where
you started and work up a sweat doing it, all while having a big grin.

Colin

Hi Colin,

I was having a lot of fun in the Robinson until I made the mistake
of looking through the NTSB accident database. Wow! Those things
have a _much_ higher accident rate for the hours flown than
other helicopters. The main rotor loss of control accident rate
was 4x higher than the next worse helicopter (Bell 204).

(oddly enough, the Bell 206 had the lowest loss of control accident
rate for the hours flown at .015 fatal LOC accidents per 100K flight
hours.)

This is based on data taken from 1981 - 1994, and can be found
on page 12 of the following PDF:

http://www.ntsb.gov/publictn/1996/SIR9603.pdf

Scary stuff!!

Don W.


COLIN LAMB wrote:
Hi Don:

Yes, we are taught that if the rpm gets too low, we are dead. If the rpm
gets too high, the gearbox is blown. Keep the rotor in the green or you may
not walk away - and you have 1.75 seconds to drop the collective when the
engine quits in the Schweizer - even less in the Robinson.

But, where else can you pay $200 per hour to move one foot away from where
you started and work up a sweat doing it, all while having a big grin.

Colin

Don W wrote:

Hi Colin,

I was having a lot of fun in the Robinson until I made the mistake
of looking through the NTSB accident database. Wow! Those things
have a _much_ higher accident rate for the hours flown than
other helicopters. The main rotor loss of control accident rate
was 4x higher than the next worse helicopter (Bell 204).

(oddly enough, the Bell 206 had the lowest loss of control accident
rate for the hours flown at .015 fatal LOC accidents per 100K flight
hours.)

This is based on data taken from 1981 - 1994, and can be found
on page 12 of the following PDF:

http://www.ntsb.gov/publictn/1996/SIR9603.pdf

Scary stuff!!

Don W.


COLIN LAMB wrote:

Hi Don:

Yes, we are taught that if the rpm gets too low, we are dead. If the
rpm gets too high, the gearbox is blown. Keep the rotor in the green
or you may not walk away - and you have 1.75 seconds to drop the
collective when the engine quits in the Schweizer - even less in the
Robinson.

But, where else can you pay $200 per hour to move one foot away from
where you started and work up a sweat doing it, all while having a big
grin.

Colin




When you finally find out what's really going on,
helicopters are about the scariest machines ever made.

Some argue - second to "nuclear reactors built by the lowest bidder",
but that doesn't detract much from the claim...

If they were not so - unbelievably useful -
they would never be built.

- - - - - - -- - - - - - - - - - - - - - - - - - - - - - - - -

Rotor rpm decay rate is a function of rotor inertia.

Robinson R-22 grosses 1370 pounds.

At an average 3300 pounds gross, the Bell 206 over twice as heavy.
And Bell makes special comment on the 206 high inertia rotor system.
Turbine time too.

Even a die-hard fixed wing fanatic has to admit,
that's a hell of an airplane.


Have fun having fun!


Richard

The Robinson requires more training time than the Schweizer. I think I
calculated that you have about 1.75 seconds to go into autorotation in a
Schweizer if the engine quits, but less than a second in a Robinson. With
practice, the 1.75 seconds is a piece of cake. I have never flown a 206,
but they sound wonderful.

Going through the FAA rotorcraft book (free on the internet), there are 8 or
9 easy ways to get into trouble with a helicopter. The gyrocopter, on the
other hand, only has a a couple - and those can be remedied. However, the
gyrocopter cannot hover.

Colin