Bell 427 Main Rotor System

Is anyone out there familar with the design of the Bell 427 main
rotor? Since I first saw it I've been quite a fan of the design with
it's composite yoke for coning and flapping relief and it's rather
novel and very simple damping elements. Yet today I read that Bell
plans to re-rotor the 427 within the next year. Does anyone know why?

Is anyone out there familar with the design of the Bell 427 main
rotor? Since I first saw it I've been quite a fan of the design with
it's composite yoke for coning and flapping relief and it's rather
novel and very simple damping elements. Yet today I read that Bell
plans to re-rotor the 427 within the next year. Does anyone know why?


In the early days of flight the engineers also flew the aircraft which had the
effect of eliminating bad engineerings very quickly. Today it seems as if Bell
has all the test flying done by line pilots. 407, case in point, 427, case in
point.

The 427 rotor was ported over virtually unchanged from the 407. It was
originally designed for the Bell Model 400 back in the '70s, a design that
was never fielded but was very similar to the unlamented Soloy Twin Ranger,
was produced in quantity for the OH-58D, and was maxed out in terms of disc
loading and gross weight capacity before the 427 came along. The 427 will
never have competitive range and payload with the current rotor, something
that was obvious when it was still on paper 7 years ago. Bell's late, great
Ed Covington, Chief Engineer for rotor design, calculated in the spring of
'97 that the 430 hub could be ported to the 427 with little change. It
should have been done then.


"Shaber CJ" wrote in message
...
Is anyone out there familar with the design of the Bell 427 main
rotor? Since I first saw it I've been quite a fan of the design with
it's composite yoke for coning and flapping relief and it's rather
novel and very simple damping elements. Yet today I read that Bell
plans to re-rotor the 427 within the next year. Does anyone know why?


In the early days of flight the engineers also flew the aircraft which had
the
effect of eliminating bad engineerings very quickly. Today it seems as if
Bell
has all the test flying done by line pilots. 407, case in point, 427,
case in
point.

The 427 rotor was ported over virtually unchanged from the 407. It was
originally designed for the Bell Model 400 back in the '70s, a design that
was never fielded but was very similar to the unlamented Soloy Twin Ranger,
was produced in quantity for the OH-58D, and was maxed out in terms of disc
loading and gross weight capacity before the 427 came along. The 427 will
never have competitive range and payload with the current rotor, something
that was obvious when it was still on paper 7 years ago. Bell's late, great
Ed Covington, Chief Engineer for rotor design, calculated in the spring of
'97 that the 430 hub could be ported to the 427 with little change. It
should have been done then.
Jim, thanks for the information. It is rather a same that American Helicopter
manufacturers are not competitive with Europe. Maybe a clean sheet of paper
would help. It seems the B206 has been recertified enough. It is just poor
engineering and poor management to have to re-rotor already certified
helicopters.

"Shaber CJ" wrote in message
...
The 427 rotor was ported over virtually unchanged from the 407. It was
originally designed for the Bell Model 400 back in the '70s, a design
that
was never fielded but was very similar to the unlamented Soloy Twin
Ranger,
was produced in quantity for the OH-58D, and was maxed out in terms of
disc
loading and gross weight capacity before the 427 came along. The 427
will
never have competitive range and payload with the current rotor,
something
that was obvious when it was still on paper 7 years ago. Bell's late,
great
Ed Covington, Chief Engineer for rotor design, calculated in the spring
of
'97 that the 430 hub could be ported to the 427 with little change. It
should have been done then.
Jim, thanks for the information. It is rather a same that American
Helicopter
manufacturers are not competitive with Europe. Maybe a clean sheet of
paper
would help. It seems the B206 has been recertified enough. It is just
poor
engineering and poor management to have to re-rotor already certified
helicopters.

Gotta agree with this statement. I have been a diehard Bell supporter for
many years (205, 206, 212) and I am also S-70 (UH-60) trained. Last year I
switched allegances to Eurocopter (EC-665 Tiger) and I must confess that in
my opinion (only), EC have it all over Bell and Sikorsky for rotorcraft
design and their manufacturing technologies. This Tiger is an absolute work
of art.

(Shaber CJ) wrote in message ...
The 427 rotor was ported over virtually unchanged from the 407. It was
originally designed for the Bell Model 400 back in the '70s, a design that
was never fielded but was very similar to the unlamented Soloy Twin Ranger,
was produced in quantity for the OH-58D, and was maxed out in terms of disc
loading and gross weight capacity before the 427 came along. The 427 will
never have competitive range and payload with the current rotor, something
that was obvious when it was still on paper 7 years ago. Bell's late, great
Ed Covington, Chief Engineer for rotor design, calculated in the spring of
'97 that the 430 hub could be ported to the 427 with little change. It
should have been done then.
Jim, thanks for the information. It is rather a same that American Helicopter
manufacturers are not competitive with Europe. Maybe a clean sheet of paper
would help. It seems the B206 has been recertified enough. It is just poor
engineering and poor management to have to re-rotor already certified
helicopters.

Thanks for the info. You can see that they are virtual clones. Still
very creative and extremely simple. I must have misread the article, I
thought that it said that they intended to design a brand new
articulated rotor. I can't understand why when like you said they have
a BMR from the 430 that they could retrofit.

Bob M wrote:

Thanks for the info. You can see that they are virtual clones. Still
very creative and extremely simple. I must have misread the article, I
thought that it said that they intended to design a brand new
articulated rotor. I can't understand why when like you said they have
a BMR from the 430 that they could retrofit.

They may very well intend to design a new articulated rotor, but I doubt it.
The current rotor is semi-articulated witha composite yoke. They may just
try to scale it up, but the stacked hub bearingless rotor from the 430 is a
mature technology now with the scaled up versions implemented on the UH-1Y
and AH-1Z. On the other hand, no one has actually built a yoke like that
for a mast as skinny as the one on the 427. Still, once it's implemented
and successful in practice, look to see it ported to the 407 -- although
that would necessitate redundant hydraulics for the 407. Great ship, if it
were just a little easier boost off.

I was wrong. I checked with Bell and they will indeed field a new
articulated rotor. The design gives superior CG range compared to the
limited flapping of the 430 type head.

"Jim Burt" wrote in message
...
Bob M wrote:

Thanks for the info. You can see that they are virtual clones. Still
very creative and extremely simple. I must have misread the article, I
thought that it said that they intended to design a brand new
articulated rotor. I can't understand why when like you said they have
a BMR from the 430 that they could retrofit.

They may very well intend to design a new articulated rotor, but I doubt
it.
The current rotor is semi-articulated witha composite yoke. They may just
try to scale it up, but the stacked hub bearingless rotor from the 430 is
a
mature technology now with the scaled up versions implemented on the UH-1Y
and AH-1Z. On the other hand, no one has actually built a yoke like that
for a mast as skinny as the one on the 427. Still, once it's implemented
and successful in practice, look to see it ported to the 407 -- although
that would necessitate redundant hydraulics for the 407. Great ship, if
it
were just a little easier boost off.