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Gust Lock

Bwing96

Active Member
This past week end we evidently had some strong winds hit during the night around the airport where I keep my RV-6 tied under a shed. Several items were blown around the yard. My plane is tied facing due North and the wind was from the South. I'm glad I had the lap belt extension wrapped twice around the control stick. All control surfaces appeared to be fine except for my flaps which were fully extended. The wind was strong enough to over-extend them and the flap motor wouldn't attempt to retract them. I carefully worked the taped edge back under the skin on the wing and they popped back into place, I cannot find anything that is bent or damaged.

It still flies straight and the flaps work as they did before. I contacted Anti- Splat about a control lock and will have to take some pictures and do a little measuring so they can produce a gust lock that will fit the stick which has 2 bends in it. Also I won't be leaving my flaps fully extended again.
 
I will forever be grateful to the VAFer who sent me a GustBuster, especially with some of the recent threads. I recognize now the danger of having control surfaces rigidly locked in place .
 
what is the "danger of having control surfaces rigidly locked" ?

would it not be the same as the danger of the flight surfaces being rigid ?
 
This past week end we evidently had some strong winds hit during the night around the airport where I keep my RV-6 tied under a shed. Several items were blown around the yard. My plane is tied facing due North and the wind was from the South. I'm glad I had the lap belt extension wrapped twice around the control stick. All control surfaces appeared to be fine except for my flaps which were fully extended. The wind was strong enough to over-extend them and the flap motor wouldn't attempt to retract them. I carefully worked the taped edge back under the skin on the wing and they popped back into place, I cannot find anything that is bent or damaged.

It still flies straight and the flaps work as they did before. I contacted Anti- Splat about a control lock and will have to take some pictures and do a little measuring so they can produce a gust lock that will fit the stick which has 2 bends in it. Also I won't be leaving my flaps fully extended again.

... We are very glad to have the opportunity to help you with your gust lock special needs. When installed you will be assured of having the worlds finest, affording you the ultimate in protection for your aircraft. The custom fitting for your modified stick will be no added charge and only take a day or so. We know you will be delighted with the product and are proud to say, "with sales of over 2300 units and climbing, we don't have an unhappy customer." Thanks, Allan... :D
 
what is the "danger of having control surfaces rigidly locked" ?

would it not be the same as the danger of the flight surfaces being rigid ?

Engineering source:

http://www.wildblueinnovations.com/Engineering--Wind-Load-Info-.html

"A wind gust of 50 kts. produces 71 lbs. of force on the RV7, 9 and 10 rudders. With the rudder deflected 35 degrees the wind load is reduced to 58 lbs of force."

Where do we find that 71 lbs of force is bad/damaging and 58 pounds of force is acceptable? If someone had a shaped rigid board system that sandwiched the vertical stabilizer and rudder such that the rudder could not move, would that be bad or OK under the 50 knot side gust scenario?

This is an important issue considering some reported info about a recent event.
 
Rudder Damage

The goal of the Gust Buster design is to managewind energy in a way that mitigates the potential for damage during threatening higher energy wind events.

RV rudder damage reports indicate that the rudder will experience structural damage during winds at or near 50 knots and at or near 90 degrees to the rudder if the rudder is rigidly locked. (You can do a search on VAF and read some of these reports). 50 knots of wind is about 71lbs of force on a surface area the size of an RV-7,9 or 10 rudder. Allowing the rudder to move against spring pressure to 35 degrees of deflection will reduce the load on the structure to about 58lbs. That's better than 71lbs where damage reportedly takes place. This is only part of what the Gust Buster system does. Read On.

The Advantage of the Springs

1) In most cases the compressed spring becomes the rudder stop sparing the airplanes mechanical stop from any abuse, (this is the case when the rudder control is used on the rudder pedals that the cables are connected to).
2) The springs also act as shock and energy absorbers during gusts when the rudder is most vulnerable to damage. 3) Depending on the type of airplane the spring will absorb approximately 40 lbs. to 49 lbs. of additional force on the rudder while it is compressing during rudder travel.

The springs give the energy an alternate path. If the rudder is rigidly locked the energy has nowhere to go but into the structure.

Flight controls are, as the name implies, designed for flight not life on the ramp. On the ramp they need all the help they can get as they are far more fragile than the components they are attached to.
 
Loal - I was not suggesting I use a lock located at the stick or rudder pedals. I was more asking what Ron was suggesting - what happens when the control surface is united with the corresponding flight surface.

Good links and information all around. Thanks.
 
The goal of the Gust Buster design is to managewind energy in a way that mitigates the potential for damage during threatening higher energy wind events.

RV rudder damage reports indicate that the rudder will experience structural damage during winds at or near 50 knots and at or near 90 degrees to the rudder if the rudder is rigidly locked. (You can do a search on VAF and read some of these reports). 50 knots of wind is about 71lbs of force on a surface area the size of an RV-7,9 or 10 rudder. Allowing the rudder to move against spring pressure to 35 degrees of deflection will reduce the load on the structure to about 58lbs. That's better than 71lbs where damage reportedly takes place. This is only part of what the Gust Buster system does. Read On.

.

Isn't the assumption here that the wind will always be 90 degrees to the airplane? What if the wind starts as a quartering tailwind, and the springs allow the rudder to move against the stops where it really is perpendicular to the wind, and faces more force?

IMO, the more you can do to minimize, then distribute the wind load the better. Flaps UP, ailerons fixed in the neutral position, same with the elevator. For the rudder, ideally you would have one system that locks the rudder via the pedals, and another external lock. That way, the force is distributed over more structure, and neither rudder lock takes 100% of the load.
 
Gust Control

We do not assume the wind will always be 90 degrees to the airplane. However, nearly all the damage reports we have been able to find and read were of that scenario so we use it as a starting point to explain how our product works. The angle certainly does matter.
In a quartering tail wind situation you would loose the deflection benefit of the system but you would still have the benefit of the spring to absorb wind energy. If the system is properly adjusted the spring when fully compressed will become the stop the rudder will not contact the airplanes stop. Thanks for your thoughts, we continue to search for ways to control this threat.
 
.....If the quoted numbers in this thread were capable of damaging one of the control surfaces I would have been dead several hundred times. The aerobatics I have subjected many many airplanes to, would have most assuredly ripped off control surfaces like tar paper were this the case. Wind will not harm a control surface that is in a neutral position and and held there. With the exception of tornadoes and hurricanes, where your concern will be the tie-downs and anchor points. All factory supplied gust and lock devices are constructed this way and have worked well since there conception. Cessna says "If it is moving it is wearing out". Piper states Restrain all controls when parked outside unattended". Beech aircraft supplies a lock and pin arrangement and all other certified aircraft manufacturers do as well. Almost always, wind damage occurs when the surfaces are not streamlined and or restrained. They get a violent run at and crash into the stops with a damaging hammer type blow and this is when the problem occurs. Nowhere can one find a single report of wind damage with a restraining gust lock installed and in tact. The only exception being when tie-downs fail and the aircraft is blown over. Trying to make the surfaces flap around in the wind is like saying the wings need to flap to keep them from breaking off.....:D
 
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All kidding aside, I will be getting Allen's lock when I get there, I have the seat mod and will do the nose wheel bearing also. There is a lot of work that goes into putting something to market. Sure it cost money, but why would anyone make these things if there was no profit ?
 
I use this:
http://www.aircraftspruce.com/catalog/pspages/vansrvcontrollock.php?clickkey=6001

and this:
https://missions.capnhq.gov/ops/dot/school/gustlock/L-23rudderlock.htm

I made several versions. they are portable, light and uber easy to install.

rudderlock1.gif


13-11269CL.jpg
 
.....If the quoted numbers in this thread were capable of damaging one of the control surfaces I would have been dead several hundred times. The aerobatics I have subjected many many airplanes to, would have most assuredly ripped off control surfaces like tar paper were this the case. Wind will not harm a control surface that is in a neutral position and and held there. With the exception of tornadoes and hurricanes, where your concern will be the tie-downs and anchor points. All factory supplied gust and lock devices are constructed this way and have worked well since there conception. Cessna says "If it is moving it is wearing out". Piper states Restrain all controls when parked outside unattended". Beech aircraft supplies a lock and pin arrangement and all other certified aircraft manufacturers do as well. If brackets, springs, rubber bands and bungee cords were the answer, then that would be the norm. Almost always, wind damage occurs when the surfaces are not streamlined and or restrained. They get a violent run at and crash into the stops with a damaging hammer type blow and this is when the problem occurs. Nowhere can one find a single report of wind damage with a restraining gust lock installed and in tact. The only exception being when tie-downs fail and the aircraft is blown over. Trying to make the surfaces flap around in the wind is like saying the wings need to flap to keep them from breaking off.....:D

Alan, just wanted to pass along a little info. If you do a search on this forum
titled "Rudder Damage and Cure" you will find a report of an RV 7A owner who suffered rudder damage while the rudder was locked rigidly during winds 30 gusting to 50. The engineer calculates that the a 50kt wind load on an RV 7,9, or 10 rudder, which have about the same surface area, will produce 71lbs of force on the rudder. Since this force is delivered in the form of the sudden impact of a gust damage seems to be a given.

The Gust Buster does not allow the flight controls to "flap around." It is a Gust Buster not a Breeze Buster. The control surfaces do not move until the wind gusts approach 35 it varies some depending on the airplane. Since the springs resistance increases as it compresses it takes much more wind than that to move them near the stops at that point the compressed spring will become the stop. All springs do is absorb or store energy, but they do that well as do bungee cord.

In flight you get a lot of immediate response from fairly low pressure control inputs. The airplane moves with the slightest flight control input and limits the stress on the control surface. What would happen if a generous rudder input was made during flight and the airplane did not move? This is more akin to the scenario of the airplane being tied down on the ramp during a high energy wind event with the controls rigidly locked. The structure has to absorb all of the energy. Or we can let it move before it bends.

I believe you have some very good products and I wish you well.

By the way we are offering free popcorn with every Gust Buster purchase!
 
I've yet to settle on what I'm going to do for my RV-6 regarding gust protection, and I hadn't seen the gustbuster product yet. With the, um, lively discussion and all this has been quite educational.

All I can say is:

threaddelivers.jpg
 
Alan, just wanted to pass along a little info. If you do a search on this forum
titled "Rudder Damage and Cure" you will find a report of an RV 7A owner who suffered rudder damage while the rudder was locked rigidly during winds 30 gusting to 50. The engineer calculates that the a 50kt wind load on an RV 7,9, or 10 rudder, which have about the same surface area, will produce 71lbs of force on the rudder. Since this force is delivered in the form of the sudden impact of a gust damage seems to be a given.

The Gust Buster does not allow the flight controls to "flap around." It is a Gust Buster not a Breeze Buster. The control surfaces do not move until the wind gusts approach 35 it varies some depending on the airplane. Since the springs resistance increases as it compresses it takes much more wind than that to move them near the stops at that point the compressed spring will become the stop. All springs do is absorb or store energy, but they do that well as do bungee cord.

In flight you get a lot of immediate response from fairly low pressure control inputs. The airplane moves with the slightest flight control input and limits the stress on the control surface. What would happen if a generous rudder input was made during flight and the airplane did not move? This is more akin to the scenario of the airplane being tied down on the ramp during a high energy wind event with the controls rigidly locked. The structure has to absorb all of the energy. Or we can let it move before it bends.

I believe you have some very good products and I wish you well.

By the way we are offering free popcorn with every Gust Buster purchase!

.... I went to the thread referenced above and read the entire thing. The failures were from the rudder impacting the stops and subsequent rivet failure. The vans type u-bent piece of wire is not adequate to hold the surface and if one is inclined to use this method then at least install one on the other side. I will say that it would be advisable to install some extra rivets in the trailing edge of the rudder, at least at the bottom 8 or 10 inches. I will do this immediately. A hard slip, snap roll or a tail slide well definitely induce more load on this surface than a 50 knot wind.

.... If an impact or violent gust occurs, our system actually will allow limited movement that progressively increases tension with distance. This is accomplished via a torsion action of the chrome molly 4130 tube employed in the "Ultimate Gust Lock". This will happen long before sufficient force is applied to bend or fail the surface or its attach point.

.... Please don't think I am saying your offering does not work as advertised, quite the opposite. It will definitely perform as stated. We feel our solution is better of course as it offers instant snap on and off while still seated in the pilot seat, thus encouraging its more frequent use, weighing less than a pound, its very small, requires almost no storage space, will never rot or require replacement (lifetime warranted) and most importantly, it looks sexier.

.... We don't offer popcorn (gets soggy in shipping) with the purchase of "The Ultimate Gust Lock", but we do offer a free, beautifully embroidered very high quality hat and still make the $10 donation to charity as well....:D
 
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Perhaps we aren't reading the same thread. In the one I was referring to the RV-7A owner stated he used a .125 aluminum lock and attached it with bolts.

He also reported that his rudder was damaged while using this method. The rudder did not hit the stop or the elevator until the lock was removed and the wind caught it while making repairs. See below.

Got work to do........ Time will tell the story.


The rivets actually pulled through the skin and did not shear. I believe they were fully set and the parts were bonded with fuel sealant. The only other damage occured forward of the rivets along the rudder skin itself. There was apparant buckling of the skin which can be seen a bit in the picture. I believe the difference between flight loads and wind gusts loads was due to the gusty nature of the winds. We were in the nearby town during the storm where the wind wasn't actually that bad. By the time we got to the airport the airplane has been subjected to the gusty winds for over 12 hours. The winds were so strong that the local commuter aircraft cancelled flights that day.

Our bad day continued as we backed the airplane into the garage and removed the rudder lock. The rudder lock was not as tight as it usually is and I noticed a slight elongation on the bolts holes were the lock attached. This may have contributed to the loads on the rudder as it was actually able to swing 10-20 degree back and forth. So with the rudder now free swinging I went back inside the building to borrow a drill. The wind caught the rudder (still inside the garage) and slamed it against the elevator. and the wind caught it while making repairs.
 
It would appear that most of the common reports of damage from a rudder horn locks can be attributed to the mechanical advantage the wind has relative to that small location.
 
It would appear that most of the common reports of damage from a rudder horn locks can be attributed to the mechanical advantage the wind has relative to that small location.

That may be true. Is an in-cabin PVC rudder lock that butts up against the spar area better?
 
.... If someone had a shaped rigid board system that sandwiched the vertical stabilizer and rudder such that the rudder could not move, would that be bad or OK under the 50 knot side gust scenario?

This is an important issue considering some reported info about a recent event.

My old flying club was on the windward side of an island. We saw regular wind events with winds gusting occasionally to 50+kts.

We used padded 1x6 boards and toggle bolts to lock the Rudders into the neutral position. The boards had thick enough padding that there was a slight give to the rudder surface.

This, and using a phone list to call members in to help turn birds into the wind, when wind direction was other than prevailing, seemed to work quite well.
 
That may be true. Is an in-cabin PVC rudder lock that butts up against the spar area better?

I have one of those and an external lock (PVC pipe covered with pipe insulation). I believe the combination is better than any single point solution. IMO, the goal is to prevent absorb gust loads at more, rather than fewer, points.

The 1x6 padded boards mentioned by another poster would be a better solution than my PVC external restraint, but they would be awfully heavy to carry around on every overnight X/C.
 
That may be true. Is an in-cabin PVC rudder lock that butts up against the spar area better?

My buddy's RV7A and my RV6 were parked side-by-side during the storms at OSH 2012. He had internal PVC rudder locks. I used PVC external locks. He suffered hole in rudder along with some other damage. No damage to my plane. This year he switched to external locks. FWIW.
 
The 1x6 padded boards mentioned by another poster would be a better solution than my PVC external restraint, but they would be awfully heavy to carry around on every overnight X/C.
Lightening holes? I'd think you could remove 50+% of the wood and still have plenty of strength. Good conversation. I might fabricate myself a rudder lock out of wood and foam... Maybe composite foam/fiberglass with soft foam overlay... hmmm.
 
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