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totally enclosed linkages..looking for troubles

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Old 08-16-2012, 09:34 AM
  #1
DelGatoGrande
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Default totally enclosed linkages..looking for troubles

..ok here it goes ..i try to hide my rudder servo..
what option we have for a totally enclosed linkage setup?

Im not interesting in a torque tube solution (torque tube= extended rod on the hinge line in the fuse)
or for "flap" setup with one side to be the hinge.

Im looking for center hinge set up for simetrical move with the servo in the fin.


How about the swingees ? Have try them on a small glow but for jet use is there any heavy duty edition out there im not aware of? ...or im looking flatter troubles here cause might grow a slop?

How the full scale set up theres?


Thanx for your time and the info in advance gents.
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Old 08-16-2012, 10:22 AM
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Default RE: totally enclosed linkages..looking for troubles

A full scale king air uses a torque rod setup that goes into the tailcone. Which then bolts to a control arm that has 2 cables on it and a spring on either side.
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Old 08-16-2012, 10:29 AM
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Default RE: totally enclosed linkages..looking for troubles

The BVM Rafale used a 1/4" metal rod up through the hinge pivot center line up into the rudder, and is bent back around 1". The rudder has a 1/4" groove carved in a hardwood block as a receptacle for the rod. On the inside, the rod has a bellcrank with pull pull arms to the servo horn. The inner ailevators are engaged in a similar way. No external linkage. I'm not sure if my description makes sense .. maybe someone could post pics of the setup ?


~V~
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Old 08-16-2012, 10:57 AM
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Default RE: totally enclosed linkages..looking for troubles

Thank you wojtek and Thomas.. im aware of BVMs Rafale setup, but in my case i have no space left to go in the fuse for a torque tube ,thats why its out of the equation[&o]
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Old 08-16-2012, 11:05 AM
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Default RE: totally enclosed linkages..looking for troubles

I agree that swingees wouldn't be strong enough. Have you looked at the Rotary drive systems (RDS)?

http://www.irfmachineworks.com/rds/
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Old 08-16-2012, 11:44 AM
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Default RE: totally enclosed linkages..looking for troubles

hi there Sean,

im aware of RDS but dont know how slop free they can be.
They require a wide gap to work and dont know how tight the clearance will be after a number of flights or get bigger and cause flatter when centre..

plus i feel that RDS kills servos torque .. and im in a need to use a 25kg of torque servo and hoping to set it 100% travel each way


thank you
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Old 08-16-2012, 01:59 PM
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Default RE: totally enclosed linkages..looking for troubles

George

On my Boulton Paul I have a servo below the rudder with the servo centre in line with the hinge of the rudder. The servo arm has a pin at the end of it that engages with a small slot in the rudder.

John
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Old 08-16-2012, 05:44 PM
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Default RE: totally enclosed linkages..looking for troubles

I used the RDS system on both my Skymaster F-18 and F-5 for years with no problem. I just don't like seeing external linkages on rudders.

Nick

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Old 08-16-2012, 11:34 PM
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Default RE: totally enclosed linkages..looking for troubles

Hi there John

i have no space left below the rudder [&o]
If i had i would go the way you described or with torque tube.
By the way servo center dont have to be inline with rudders hinge ,the further aft servo is placed the more throw is used and less stress.

Cheers mate

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Old 08-17-2012, 12:42 AM
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Default RE: totally enclosed linkages..looking for troubles

Hi George!

Just get some decent RDS linkages. Graupner has them for standard servos and I am using them in a Jetco XL on the rudders. The linkage is as slopfree as you get ist with regular linkages and once aou understand how it works and how to mount it right, you will not loose any torque.

Best regards,

David
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Old 08-17-2012, 12:44 AM
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Default RE: totally enclosed linkages..looking for troubles

I have only used Swingee's once on the rudder of a 40 size model.
It was slop free for a while until I bumped the rudder getting it into
the car. It then had miles of slop & being buried in the fin I made a
real mess removing it.

My BVM Sabre uses a torque rod with a metal arm on the end. Cables
then to a servo mounted forward. Doesn't take up much room & being
all metal would be heat resistant. It's not real solid though & feels a bit
springy. Room for that set up? John.
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Old 08-17-2012, 05:31 AM
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Default RE: totally enclosed linkages..looking for troubles

Hi there David,
this heavy duty RDS looks better...my rudders is tall so i might use two RDS servos in it and mach them from my powerbox !

..is there a place to find this in stock? Graupner says in a year time http://www.graupner.de/en/products/3928/product.aspx

lindinger and schweighofer have them out of stock too[&o]

danke



...John no room at all mate [&o]
thanx
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Old 01-25-2013, 09:30 AM
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Default RE: totally enclosed linkages..looking for troubles

Hi guys,

Sorry to dig up a (relatively) old thread but this is what my search turned up.

I am looking for these same internal linkages. I saw what Dave Platt had on his hunter (swingees) and I was not impressed with those (although a local super builder used them for years on DF speed planes).

As for RDS, Nick how fast would you say you had that F5 up to? It seems to have the advantage of a relatively short rudder. I am interested in how hard (fast) people have pushed these RDS systems.

I looked at them several years ago, and to me the only relative disadvantage was the potential for slop in that pocket. The fit between the rod and the pocket is critical. What do you say Nick, any more details you can share?
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Old 01-25-2013, 10:46 AM
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Default RE: totally enclosed linkages..looking for troubles



I end up going with torque tube and like it a lot.

Made some test with RDS and didnt like them .One weak spot is that RDS trying to split/open the fin side at the rod exit hole.
Another down side is that connection direct on servo gear kills resolution big time since you reduse alot the end points.


RDS not for jet use..at least for me
my 2c
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Old 01-25-2013, 04:16 PM
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Default RE: totally enclosed linkages..looking for troubles

If you have to reduce the end points to much in a RDS system, you can always go with a different bend angle in the rod, as the rod bemd angle dictates the surflace deflection angle
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Old 01-25-2013, 05:54 PM
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Default RE: totally enclosed linkages..looking for troubles

Thomas you beat me to it. My question is, does the reduced bend angle increase the affect of slop in the linkage pocket?
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Old 01-26-2013, 04:40 AM
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Default RE: totally enclosed linkages..looking for troubles

Matt,
The pockets are normally made from a very stronf but smooth material (g10 or formica). I buy the premade pockets from irf machine works and they are a snug but smooth fit in the wires. As long as the wire is a good tight fit with no slop and the servo and surface is hinged securely there should be minimal to no slop in the system.

The way the bent wire was described to me, was comparing it to a conventional control horn. A 45* bend was like a 1" horn, 22.5* like a 2" horn, etc. the bend angle dictates deflection angle.

Thomas
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Old 01-26-2013, 10:40 AM
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Default RE: totally enclosed linkages..looking for troubles

Could someone post a picture of the BVM torque tube linkage? I'm in the same predicament right now and I'm trying to find a functional, reliable and relatively simple solution. I do have a lot of room below the rudder and to the side of the elevators so the torque tube linkage might be really perfect. I know... I want it all - easy, fast and cheap. Well I know it won't be cheap it never is cheap with jets.
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Old 01-26-2013, 11:52 AM
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Default RE: totally enclosed linkages..looking for troubles

Quote:
ORIGINAL: mr_matt

Hi guys,

Sorry to dig up a (relatively) old thread but this is what my search turned up.

I am looking for these same internal linkages. I saw what Dave Platt had on his hunter (swingees) and I was not impressed with those (although a local super builder used them for years on DF speed planes).

As for RDS, Nick how fast would you say you had that F5 up to? It seems to have the advantage of a relatively short rudder. I am interested in how hard (fast) people have pushed these RDS systems.

I looked at them several years ago, and to me the only relative disadvantage was the potential for slop in that pocket. The fit between the rod and the pocket is critical. What do you say Nick, any more details you can share?

Matt:

I would say that my SM F-18 was flying no faster than about 150 mph, but the top speed for my SM F-5 was about 170mph. As Thomas stated, I always purchased the pre-built pockets (very strong and I embedded them in aeropoxy) plus the "Heavy Duty - 1/8in" version torque rods from IRF Machine and used digital "wing servos". There was absolutely no slop in that original version from IRF Machine.

Nick


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Old 01-27-2013, 03:26 AM
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Default RE: totally enclosed linkages..looking for troubles

Quote:
ORIGINAL: Eddie P

Could someone post a picture of the BVM torque tube linkage? I'm in the same predicament right now and I'm trying to find a functional, reliable and relatively simple solution. I do have a lot of room below the rudder and to the side of the elevators so the torque tube linkage might be really perfect. I know... I want it all - easy, fast and cheap. Well I know it won't be cheap it never is cheap with jets.

thats a SkyMaster torque tube(rod) i use
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Old 01-27-2013, 08:33 AM
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Default RE: totally enclosed linkages..looking for troubles

Thanks DGG. There is also another method of using a pin mounted to a servo arm where the servo is mounted in the fuse below the rudder - and there is a groove int he rudder base that accepts the arc movement of the servo pin. Another direct connection method with no linkage visible. I'm sure you mentioned however that you might not have the room for this? I was looking into one of these setups in a scratch build for elevator and rudder. I have a ton of room in the empennage area by the stabs and flight controls in my build. Any known disadvantage to this type of setup that you know of for elevator as well as rudder?
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