Bearing number for spindle rotor head

[Atic]

Does anyone have the bearing N° for the vintage Bensen spindle head ?
I believe it was a double row roller type spherical bearing.
A SKF replacement N° would be even more appreciated !!

Thanks

 

[gyrojake]

Skf and mrc have merged, the number is 5206

 

[Passin' Thru]

Is this head in question?

 

[C. Beaty]

Shafer A-8

 

[Atic]

gyrojake,
I think the 5206 is for the later gimbal head.

Passin' Thru,
that's the spindle head I'm referring to !

C. Beaty,
on the drawing the bearing is called : BA-A8A
Is this the same as the:Shafer A-8 ?

Many thanks guys !!

 

[C. Beaty]

Here’s a scanner shot of a live one.
There's an inner sleeve that has to be pressed out.

 

[Atic]

Thanks mr. Beaty.

I "googled" Shafer A-8-A but that doesn't turn up much.

I'm almost certain that there muist be some sort of SKF or NGK equivalent for the Shafer bearing but I cannot find it.

Thanks to everyone for the reply?

 

[C. Beaty]

Here’s the nearest match I can find from the current Shafer catalog, DAS8-32.

http://www.rexnord.com/sites/Process/Aerospace/Bearings/Documents/Shafer Bearing Catalog.pdf

The bore of Bensen A8A is 0.687 vs. 0.625 for the DAS8-32..

The later offset gimbal head provides much better stability than the original spindle head.

 

[Passin' Thru]

Chuck said:

The later offset gimbal head provides much better stability than the original spindle head.

I whole-heartedly agree!
I first learned to fly gyros using this spindle type head on a towed glider. On the glider the tow line and weight of the tow vehicle tames it down a bit, but in free flight it is absolutely treacherous! The control pressure feed-back and reactions to disturbances are exactly the opposite of self stablizing. It is trying to kill you every second!
Igor Bensen knew and admitted this in is book "A Dream of Flight".
In fact I would go so far as to state that without the introduction and adaptation of the off set gimbal rotor head, the sport gyro movement would have died in its infancy.
In short, don't fool with that thing. Get yourself a good offset gimbal head. Your entire flying experience will be much enjoyable and SAFER!

 

[C. Beaty]

Pete, I’ve never flown with a spindle head but I remember Dave Prater saying much the same thing as you.

Dave said he had a spindle head while sidekick Bill Parsons had a gimbal head; he was all over the sky while Bill looked like he was on rails. Dave claimed it was definitely not due to Bill’s superior flying skills.

I’ve built and flown rotorheads using the Shafer spherical bearing where the teeter bolt centerline passed through the center of the sphere. This amounted to the same sort of cyclic as a Bell-47 rotor where there is no component of rotor thrust fed back into the control system.

With a feedbackless head, it was a fulltime job just to stay rightside up.

But the offset gimbal head is a double edged sword. There are some very unstable gyros that give the illusion of stability. Remember the phrase; “It’s so stable it flies hands off?”

 

[Atic]

I have no intention to use the bearing as the "U-joint" but to use it in the rotorhub itself.Not for a gyrocopter though.

In the ideal world I would need a spherical roller bearing with a bore to fit over a 25 mm diameter shaft.

Someone has any idea where to find such a thing?

Many thanks for the info and reply !

 

[C. Beaty]

Download the full Shafer catalog. They have several bearings with bores of 1” and larger.

The Doblhof tip jet helicopter used a spherical bearing. Hmmmm………

 

[Atic]

Download the full Shafer catalog. They have several bearings with bores of 1” and larger.

The Doblhof tip jet helicopter used a spherical bearing. Hmmmm………

Close mr. Beaty, very close..............!!!

"A smart guy needs only half a word............."

 

[Atic]

I searched for spherical roller bearings from the "major" magnufacturers (SKF etc...) and they all start from a bore diameter of 25 mm (roughly 1").
Which obviously is what I was looking for but I was surprised that Shafer seems to be the only supplier of small diameter (1/2") bore spherical roller bearings, weird.

The bearing is for the hub of a single blade rotor.

 

[C. Beaty]

The bearing is for the hub of a single blade rotor.

Good luck.

 

[Atic]

Good luck.

Thanks mr. Beaty but I probably need more than that !!

 

[Atic]

Any chance someone has the Shafer bearing lying around doing nothing and willing to sell ?

It would greatly help to visualize what I have in mind with that rotor hub.

Thanks

 

[Rehan K.Janjua]

Hello Atic
May we know what you have in mind? Hope its other then manned flight.

Mr C.Beaty's has a remarkable memory and I quote him............
"(In fact I would go so far as to state that without the introduction and adaptation of the off set gimbal rotor head, the sport gyro movement would have died in its infancy)"

There were many certified gyros when Mr Bensen offered a KIT for home builders.

Regards
Rehan

 

[Atic]

Mr. Janjua,

I placed my question in the Bensen style gyrocopter forum because I wanted information about the bearing that was used with the spindle rotor head.

I'm just playing around with some idea's mr. Janjua for a single blade rotor which is not ment for gyrocopters.

I'm aware of the advantages and disadvantages of the off set gimbal rotor head.

Thank you for your concern though.