Swedish yoke

DarDow101

Dar
Joined
Jun 11, 2017
Messages
68
Location
Utah
After reviewing the engine mounts I made from the KB2 plans I am about convinced that .065 wall with cross tubes for bolting on the cheek plates would be sufficient. If I could figure out where to look I would look at the strengths of 2 inch .065 wall 4130 vs 2 inch square 6061 aluminum tube.
This site can help you in your search with all the spec sheets you would need.
 
Last edited:

okikuma

Member
Joined
May 21, 2006
Messages
1,914
Location
Santa Clarita, CA
Perhaps Girabet uses a round tube design for ease in manufacturing. I'm not familiar enough with this model of gyroplane to know if the 2/rev stick shake is present or has been eliminated.

Wayne
 

Kevin_Richey

Yamaha gyro...Oregon, USA
Joined
Nov 16, 2003
Messages
2,182
Location
Oregon, USA
Aircraft
Sport Copter gyroplane
Total Flight Time
300+ gyroplane, 11 airplane, 1.5 PPC, AND... a ZILLION hours of flying in my dreams!
Perhaps Girabet uses a round tube design for ease in manufacturing. I'm not familiar enough with this model of gyroplane to know if the 2/rev stick shake is present or has been eliminated.

Wayne
Based on what Chuck B. has told us many times over the years re: round, limber gyroplane masts, & that Girabet appears to leave their mast free of triangulation & attachments other than that light bracket we see up high on it, their rotorblades must be very smooth in flight.

I noticed their engine support tubing has only little attachment brackets that appear to be welded onto the lower mast section.
 

okikuma

Member
Joined
May 21, 2006
Messages
1,914
Location
Santa Clarita, CA
Hi Kevin,

I agree with the physics that Chuck has taught us.

To my eye and brain, the design and construction method for the Girabet is first for economic reasons. A simple, cut, bend, and weld, tubular airframe is much less labor intensive as compared to the Bensen style of square tube, flat plate, and right angle stock cut, debur, drill, debur, then assemble airframe. The use of round tubing is the only choice of material for the simpler method of construction. The cancelling effect of the 2/rev shake is just a second, added and positive benefit in this example.

BTW, I think the construction method for the Girabet is ingenious.

I mentioned previously about Ken Wallis' design and construction with a tubular mast and the absence of a hub bar where the rotor blades attach. I found a copy of the video Gyroplane Refrain, narrated by Roland Smith. In this one particular clip, Roland is flying with Ken Wallis on his WA-122 Rolls Royce/Continental O-240 powered gyroplane. During the flight, there is a good camera shot of how smooth/lack of vibration the cyclic is experiencing. I seriously think the combination of the tubular mast, and the lack of an extended rotor blade bar, along with finely balanced rotor blades is the secret to control the development of the 2/rev vibration.

Wayne


Wayne
 

Attachments

wolfy

Member
Joined
Dec 19, 2013
Messages
209
Location
western australia
Interesting to note, while Ken's machine's use a round mast they are all also triangulated.
Show's his rotors are very stiff in plane to have a nice smooth machine.

wolfy
 

wolfy

Member
Joined
Dec 19, 2013
Messages
209
Location
western australia
Chuck if your still reading, after looking at a mates machine (a heavy single) with .083" 4130 mast I am now convinced .065" will be more than enough for my medium weight single.
He had some .065" tube also to have a look at, sometimes just a physical look is what's needed.
So what do you think about a solid nylon insert and 6 1/4" bolts going right through, spaced an inch apart? Gang nut's will be hard to get here.

Thanks wolfy
 

C. Beaty

Gold Supporter
Joined
Apr 16, 2004
Messages
9,756
Location
Florida
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

Member
Joined
Dec 19, 2013
Messages
209
Location
western australia
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

Gold Supporter
Joined
Apr 16, 2004
Messages
9,756
Location
Florida
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

Member
Joined
Dec 19, 2013
Messages
209
Location
western australia
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

Gold Supporter
Joined
Apr 16, 2004
Messages
9,756
Location
Florida
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

Member
Joined
Dec 19, 2013
Messages
209
Location
western australia
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

Member
Joined
Dec 19, 2013
Messages
209
Location
western australia
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
 

C. Beaty

Gold Supporter
Joined
Apr 16, 2004
Messages
9,756
Location
Florida
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.
 

C. Beaty

Gold Supporter
Joined
Apr 16, 2004
Messages
9,756
Location
Florida
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

Member
Joined
Dec 19, 2013
Messages
209
Location
western australia
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
 
Top