Swedish yoke

[C. Beaty]

Tell you what I’ll do, Wolfy; send me your postal address and I'll send you enough nut plate for both ends of your mast. It’s ¼” nuts with 1 3/8” spacing so you’ll need 5” long cheek plates to accommodate 4 bolts. I won’t be able to get it in the mail tomorrow but will before the end of the week.

Years ago, hardware such as this was being disposed of as surplus and flea market dealers at major flyins were selling it for give away prices.

The next time I’m in your side of Oz, you can buy me a beer to cover my postage expense.

Speaking of nylon plugs as spacers, Bensen used wood dowels as spacers on his B-7 model that used round aluminum tube.

 

[wolfy]

Tell you what I’ll do, Wolfy; send me your postal address and I'll send you enough nut plate for both ends of your mast. It’s ¼” nuts with 1 3/8” spacing so you’ll need 5” long cheek plates to accommodate 4 bolts. I won’t be able to get it in the mail tomorrow but will before the end of the week.

Years ago, hardware such as this was being disposed of as surplus and flea market dealers at major flyins were selling it for give away prices.

The next time I’m in your side of Oz, you can buy me a beer to cover my postage expense.

Speaking of nylon plugs as spacers, Bensen used wood dowels as spacers on his B-7 model that used round aluminum tube.

Thanks Very much Chuck I have sent you a private message I think.
I have cheek plates that are about 8" long up the mast on both ends, so would still have room for about 6 bolts at that spacing.
I had read about benson's wood dowels, that's what gave me the idea for plastic to get away from the swelling and contraction with temperature/moisture. But gang nut plates are still even easier thanks.
Mate beers are on the house for you and everyone else who come's to hear you talk gyro's.

Thanks again wolfy

 

[C. Beaty]

OK Mr. Wolfe, I handed your nuts to the lady at the post office about ½ hour ago.
I cut the gang nut plate into 4 8” long pieces so that they would fit into a padded 1st class mail envelope. 1st class mail goes via air in the US and to the Australian port of entry. After that, they could be in for a long train ride if port of entry is on the East Coast.

 

[wolfy]

Thanks very much Chuck you are a champion. That beer will always be here but seriously if you need me to fix you up for any costs please let me know.

wolfy

 

[C. Beaty]

You owe me 2 beers Wolfe, postage was a bit higher than I had expected but that’ll wait.

I once had a guest from your neck of the woods, from Perth as I recall. He was a long haul truck driver, driving one of those road trains. I’ve forgotten his name, it’s been ~20+ years ago.

He was visiting Ernie, checking out Dominators and staying in Ernie’s motor home and Ernie had to make a trip somewhere and used the motor home. I put him up for several days in a metal storage building, one end of which was paneled off and fixed up as guest quarters with bathroom and air conditioning. As I think about it, the name Rodney comes to mind...

 

[wolfy]

Thanks Chuck, beers are hear whenever your ready.
Wish I could say who that truck driver could have been but 20 years ago I was still trike flying hadn't converted to rotary wing then.
I used to fly gyro's around cattle stations looking for whylie bovine so also used to steer road trains carting cattle, I only ever used to tow three trailers but now days in Oz the cattle trucks (and others) are three 40' trailers plus an 20' A trailer (the lead trailer in a B double) 4 trailers and what equates to 7 decks of cattle or about 168+ steers or 266+ weaners or 108+ bullocks and weigh around 110 tonnes.

wolfy.

 

[wolfy]

On another note Chuck or anyone else, because I went .065 wall 4130. I am thinking about using a doubler in the area of the engine support (122hp rotax). Can you see any problem with taking the doubler from the bottom of the mast up to about 4" or higher than the upper engine mount clamp? Just to gradually reduce the mast flexibility down to the solid engine clamp, if that makes sense. Was thinking of a 4130 x .065 internal doubler but don't know if that size exists yet.

Cheers wolfy

 

[wolfy]

Ok looks like 1 7/8" will slip inside perfectly.

wolfy

 

[C. Beaty]

Wolfy, without welding or bolt holes at the top engine mount clamp, there should be no need for a doubler at that station so long as the clamp doesn’t present a narrow edge to the mast; something like a ½” wide split aluminum clamp should be OK.

Be careful about aluminum on steel joints, galvanic corrosion can be a problem. There are paints and coatings that are supposed to prevent interface corrosion.

 

[wolfy]

Thanks Chuck.

wolfy

 

[wolfy]

Nut plates arrived today, Thanks very much Chuck should be a good thing.

Wolfy

 

[C. Beaty]

Good grief! 30 days for a 1st class envelope to travel from Florida to your end of Australia. Could it have been dropped off in Sydney and traveled to WA via camel train?

Probably the fires disrupted everything. Mail isn’t important when the whole country is on fire.

 

[wolfy]

Yeah I was beginning to wonder weather I balls up the address, I couldn't imagine a reason why they would have gone anywhere but Perth but stranger things have happened. I used to fly Aeros hang gliders from Ukraine. I could usually get parts in 8 - 10 days, Half the time as the parts I would get from local (Sydney) glider manufactures.

wolfy

 

[wolfy]

Mast is all sorted Chuck unfortunately will be a while before any testing can happen, but will report back the results.

wolfy

 

[C. Beaty]

OK Wolfy, but bear in mind that a flexible mast only solves the 2/rev problem.

A flexible mast does nothing for 1/rev vibration; -out of balance, out of track or out of pattern.

 

[wolfy]

Absolutely Chuck, I/rev is easy to deal with 2/rev is the real demon.
I also have a two blade helicopter and balancing equipment, I am extremely fussy about stick shake so have played lots and understand the difference. Short of having perfect track there's not a lot a balancer will help with two per rev.

wolfy

 

[DangerBird]

Very informative thread, Thanks.
I have one more question for Mr. Beaty, What would you use for a mast on a heavier 2 place to cut back or stop the shake?

 

[C. Beaty]

With a Bensen style layout where the mast points about in the same direction as the rotor thrust vector, I’d guess 2.5” with an 0.083” wall. But that’s only an off the top of my head guess; the calculation isn’t difficult but it takes a bit of time. For Eurotub style gyros where the mast leans forward, it’s probably best to avoid flexible masts and go to some kind of flexible rotorhead mount.

 

[wolfy]

Interesting Chuck, what about a vertical mast? Can we still get away with a flexible mast?

wolfy

 

[C. Beaty]

Wolfie, say the gyro weighs 1.000 lbs and the vertical mast is 4 feet long from the last brace, normally the top engine mount. The rotor thrust line is tilted toward the rear at about a 10 degree angle. The bending moment arm is then: (tan 10 degrees) x 48 inches = 8.5 inches. The bending moment is then: 1000 lb x 8.5 inches = 8,500 inch/lb = 708 ft/lb. Takes a pretty stiff piece of pipe not to bend.

That’s the reason it’s best not to stray too far from Bensen.