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  #1  
Old 08-04-2022, 08:55 PM
DeltaRomeo's Avatar
DeltaRomeo DeltaRomeo is offline
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Join Date: Jan 2005
Location: Highland Village, TX
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Default Non-engineer rudder idea for OSH gust events

Entrepreneurship / Marketing major chiming in…..be gentle.

Please don’t call me an idiot too fast, but if you could connect two pieces of angled aluminum with a full length hinge, pad the inside surfaces, place that along the entire trailing edge length of the rudder, then hold that in place with bungee type cords running to the outboard ends of the HS.

Three or four small C-clamps gingerly holding the hinged contraption in place.

In a wind event, wouldn’t this apply the same tension along the entire length of the rudder?

Silly drawing below, note the bungee that runs in FRONT of the VS for stability.

A sort of ‘last resort’ OSH thing, not a use-all-the-time type thing.

Apologies in advance if this type thing has been discussed before ….. I haven’t seen anything that applies pressure along the entire trailing edge length of the rudder. That’s what I’m trying to address here

Shields up…crawling under the porch.

V/r,dr

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Last edited by DeltaRomeo : 08-05-2022 at 09:09 AM.
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  #2  
Old 08-04-2022, 10:07 PM
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Untainted123 Untainted123 is offline
 
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Location: Azle, TX
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I think thatís probably what it would take to prevent the kind of damage we saw (basically even with gust lock, the rudders were ďtwistedĒ if the lock held, and just bashed to pieces if it failed).

But, I am wondering if instead of all that effort, how hard would it be to, at events like this where you know you arenít gonna fly again for a few days, AND we knew a storm was coming several hours in advance, to just remove the rudder altogether and stow it in the cabin, put it back on in the morning. If you made your tail light with a plug, itís only like 3 bolts right?

Just another ideaÖ
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  #3  
Old 08-05-2022, 12:51 AM
larosta larosta is offline
 
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Location: Redlands, CA
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Default

We use a simple rig called a whiffletree or Whippeltree to even distribute loads across a structure in the structural test lab. I believe that such a rig could be made from aluminum tubing or angle and some small diameter cable or low stretch line and i stalled on either side of the rudder trailing edge and anchored to the horizontal stabilizer tips or hinge points as others have done.

https://en.m.wikipedia.org/wiki/Whippletree_(mechanism)

An alternative would be a rig made from line similar to the line groups used in rigging square parachutes and paraglider canopies. Lightweight, compact, and inexpensive.

https://en.m.wikipedia.org/wiki/Paragliding#Wing

- larosta
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  #4  
Old 08-05-2022, 07:02 AM
swjohnsey swjohnsey is offline
 
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Location: Kingsville, TX
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Secure the rudder hard over to the rudder stop instead.
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  #5  
Old 08-05-2022, 07:52 AM
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rv8ch rv8ch is offline
 
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I think the trick is to have something that would simulate what you would do with your hands if you were holding the control surface during the storm.

You would probably let it move a little, and as it got closer to the stops, you would push harder.

If you were working the rudder pedals to hold it in place, you would do the same - allow it to move a bit, but push harder as you get close to the stops to avoid a slam.

Something like the anti-splat ultimate gust lock, but with hydraulic dampeners and springs to allow some movement, but not allow the control surface to hit the stops hard.
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  #6  
Old 08-05-2022, 08:04 AM
Tooch Tooch is offline
 
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Location: Amelia, Va
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Default Maybe stupid

This may sound stupid but how hard would it be to just take off the rudder for the week? P.S. I'm not a builder
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  #7  
Old 08-05-2022, 08:29 AM
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BillL BillL is offline
 
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Default Digging a little deeper.

Quote:
Originally Posted by rv8ch View Post
I think the trick is to have something that would simulate what you would do with your hands if you were holding the control surface during the storm.

You would probably let it move a little, and as it got closer to the stops, you would push harder.

If you were working the rudder pedals to hold it in place, you would do the same - allow it to move a bit, but push harder as you get close to the stops to avoid a slam.

Something like the anti-splat ultimate gust lock, but with hydraulic dampeners and springs to allow some movement, but not allow the control surface to hit the stops hard.
What would be the tension on a rudder cable with a 90 ft-lb torque? 360#? The Gustbuster guy calculated 90lb for the tall 7/9 rudder is that in the ball park?

What torque on the rudder horn is acceptable? Is it the same for an 8 (.020 skin), 7/9, 14? That is three are different designs.

To the OP . . . Gotta say, the idea of something covering maybe 18" of the TE might me enough to carry the loads with a single cord. A bungee with rope stop backup on both sides. Structure to transfer the loads to the elevator safely also are a potential factor. We need something easy to install, carry the loads, and be easily stowed. If the 7/9 rudder was restrained just above the HS then we have about 20" from the pivot making about 50 lbs to restrain. 18" of TE contact gives 3 lb/in if that means anything.

My mind keeps slipping into Vans design world for the answers.

I'll bet some Vans engineers are talking about this already. 80% chance (opinion) they will develop a recommendation as a result of all this.
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Last edited by BillL : 08-05-2022 at 09:20 AM.
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  #8  
Old 08-05-2022, 10:49 AM
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Mike S Mike S is offline
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I wonder how a couple wedges of fairly dense foam between the rudder and inboard ends of the elevators would work?? Big enough to fill the entire area between rudder and elevators.

Dense as in pool noodles or such.

Would need some way to keep the wedges in place.

Would absorb gust loads and return to neutral all on its own.
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  #9  
Old 08-05-2022, 11:05 AM
Paul 5r4 Paul 5r4 is offline
 
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After seeing some of the damage to rudders at HBC, Just yesterday I was experimenting with new ideas to secure the rudder. I do believe it MUST be supported at the trailing edge for best results/hopes of no damage. My idea was elastic cords placed in two or three places at the back. Even considered dr's idea of a full trailing edge device.

I did fabricate my idea and tried it out. I feel the elastic theory is a good idea for one main reason. If the rudder is subjected to loads and can actually move some, then it will essentially dump "a part" of the load as the rudder tries to weathervane. The idea is the elastic cords would stop the rudder before it can make contact with the stop on the downwind side. He's the weird thing. As I stood there with this in place it feels as if the rudder is almost loose despite tension in place on both sides from the elastic cords. It's because of the tension being exerted on the pulling side. In other words it took very little pressure from my fingers to move it left or right because the elastic cords were assisting by pulling. The further it was displaced from center, the more tension the opposite side applied trying to center it back up. In theory as the wind blows the rudder to one side the tension on that side lessons so that at the stop it's nearly limp on that side while the opposite side is under great tension attempting to pull it back closer to center. I just could not image as loose as it felt, (although it really wasn't loose), with everything in place, leaving it like this to weather a storm. Still thinking about this stuff and interested in others ideas as well.
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Last edited by Paul 5r4 : 08-05-2022 at 11:18 AM.
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  #10  
Old 08-05-2022, 11:30 AM
rocketman1988 rocketman1988 is offline
 
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Location: Sunman, IN
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Default

Quote:
Originally Posted by Paul 5r4 View Post
After seeing some of the damage to rudders at HBC, Just yesterday I was experimenting with new ideas to secure the rudder. I do believe it MUST be supported at the trailing edge for best results/hopes of no damage. My idea was elastic cords placed in two or three places at the back. Even considered dr's idea of a full trailing edge device.

I did fabricate my idea and tried it out. I feel the elastic theory is a good idea for one main reason. If the rudder is subjected to loads and can actually move some, then it will essentially dump "a part" of the load as the rudder tries to weathervane. The idea is the elastic cords would stop the rudder before it can make contact with the stop on the downwind side. He's the weird thing. As I stood there with this in place it feels as if the rudder is almost loose despite tension in place on both sides from the elastic cords. It's because of the tension being exerted on the pulling side. In other words it took very little pressure from my fingers to move it left or right because the elastic cords were assisting by pulling. The further it was displaced from center, the more tension the opposite side applied trying to center it back up. In theory as the wind blows the rudder to one side the tension on that side lessons so that at the stop it's nearly limp on that side while the opposite side is under great tension attempting to pull it back closer to center. I just could not image as loose as it felt, (although it really wasn't loose), with everything in place, leaving it like this to weather a storm. Still thinking about this stuff and interested in others ideas as well.
Elastic is a bad idea...look into resonance. A perfect example is a homemade harmonica...
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