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This DOES look cool, esp. for the fearful low time pilot. As forgiving as a Cessna 172? Maybe not.
BUT the video seems to recommend a 50 lb pressure in the nose wheel. A bit high no? Won't this cause shimmy grief?
Dkb
I need to see more of the engineering behind this idea. It's obvious that he has taken the damaging forces away from the vulnerable part of the gear, but those forces are transfered somewhere else now. I want to see the result of the new forces on other parts of the gear leg and elsewhere.
I looked at the video. In theory, it appears to be a good idea.
There is an old video of the nose gear being held to the surface until it begins to oscillate fore and aft like a wet noodle. I believe that video was created by deliberately holding the NG down during acceleration way beyond normal lift off speed and may not be a valid test of real world flying.
Whether or not this modification would dampen and prevent such an oscillation and what the consequences would be with the engine mount are unknown. It should work if the clamp will hold the bracket in position and the not allow it to go off one side or the other of the strut. It is a flat piece of material, perhaps a quarter inch thick, meeting a curved surface.
I looked at an old image of the NG strut on my airplane after an off field landing and flip in 2003 in soft river bottom sand. It definitely bent where the designer of this device says the weak spot is located. But it may not have prevented the flip as the airplane was nearly stopped when it happened. The NG had been launched from a previous gradual depression on the surface, a police officer measured the distance and there was something like 20-30 feet of no tire mark, and when it contacted the surface again the front of the NG dug in and over it went. The event felt like it was in slow motion and a stiff strut may have acted as pogo arm anyhow, I don't know.
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I need to see more of the engineering behind this idea. It's obvious that he has taken the damaging forces away from the vulnerable part of the gear, but those forces are transfered somewhere else now. I want to see the result of the new forces on other parts of the gear leg and elsewhere.
I need to see more of the engineering behind this idea. It's obvious that he has taken the damaging forces away from the vulnerable part of the gear, but those forces are transfered somewhere else now. I want to see the result of the new forces on other parts of the gear leg and elsewhere.
Thanks for the post. I was beginning to think I was the only skeptic out there. While the idea looks good and sounds plausible, there is no data to support the claims nor is there any evidence to suggest the added reinforcement won't create some other unexpected problem.
The device might be better compared to a parachute or seat belt - it is only needed after the "unexpected" has happened...
I like it!
I don't think the corrosion issue will be much more than you get now with the fairing attachments and what not wearing on the gear powdercoat.
Anyone get a price yet?
Hans
Agree, I believe the price was around $379.
I wonder if Doug can work out a group buy arrangement.
I like the design approach. The added stiffener only comes into play somewhere near the point of permanent yield of the nose gear. In normal operation it should have zero effect on the nose gear characteristics.
The jig video showing the angle of the force from a small pothole explains a lot of what the -A models see just before a flip occurs.
When the device becomes operational, you are already into the realm of any "other unexpected problem" and something is about to break anyway.
The device might be better compared to a parachute or seat belt - it is only needed after the "unexpected" has happened...
One question (I emailed antisplat, waiting to hear back) - I hope this would fit under my existing gear leg fairing. Would be a pain to have to make and paint a replacement fairing to fit over this.
how much does the jig he made follow a real tire and gear set ups flex? It looks like his "tire" doesn't spin, or is it even rubber?
Intriguing product Allan. Thanks for developing it and bringing it to our attention.
I'm looking forward to seeing your site and to seeing the engineering analysis to back up the assertions made (and from what I can tell proven) in the video demo.
I like the idea of a margin of safety added to the original design. I don't consider myself immune from mishaps despite the fact that I am no longer a "low time" pilot, and I don't want to count on getting every landing 100% right to keep my plane and I intact.
It wouldn't make much difference. He is only showing the angle of forces. A real tire would actually "squish" a bit more, increasing the contact area, and actually move the angle of the force in a more "bad" direction.
It's the best explanation I have seen for the pogo stick effect that many others have reported/experienced.
As I said earlier, we should regard it as more of a seat belt/parachute idea for when stuff has already gone wrong. Operationally, Vans design is unaltered.
Allan you mention adding something to the original gear leg to get the best improvement possible. Was it too difficult to machine a different gear leg to get the improvement or not possible or to expensive?
Hey Allan - nice looking idea! I'm glad that you guys took an engineering approach to the problem and did a bunch of testing, gathering actual data. Of course that costs money - and like you said in the videos, you ruined a few gear legs along the way.
I am not nay-saying, just asking a question because that's what engineers do....A lot of the pictures of flipped "A" models and bent nose gear legs show a pretty distinct bend ABOVE the region that your brace is stiffening. Did you find anything in your testing to show that the upper bend is a result of the lower part of the strut bending first? I could picture how that would be the case, and if so, then if you prevent the mid-strut bend, you prevent the upper bend. Just curious if you ever had the strut bend above the reinforced area once you reinforced the middle, and if you have any thoughts about the bend up near the socket.
Allan,
This looks like a great product and your videos show the best explanation I've seen yet of what can occur with the Van's A-model nosewheel. While I'm no engineer, it just seems reasonable to me.
In your testing, did you calculate or test the effects of braking on the weight applied to the nose wheel?
.
Looks like he's secured his domain name, but doesn't have an actual website yet.His web site doesn't work. I ended up on Go Daddy. ?????
The bending moment is supposed to be transferred to his brace so the NG doesn't bend in the area where the brace is. So in a significant NG incident, the NG is still going to suffer damage, but not so that it curls under the aircraft.I need to see more of the engineering behind this idea. It's obvious that he has taken the damaging forces away from the vulnerable part of the gear, but those forces are transfered somewhere else now. I want to see the result of the new forces on other parts of the gear leg and elsewhere.
Don't think so...I believe it's designed to prevent catastrophic failure (i.e. total NG collapse) leading to nose-over accidents...not designed to prevent NG failures generally.I mean it would likely prevent far more failures than it would cause.
Unlikely. This brace is clearly designed not to prevent the NG oscillating or even to prevent the NG from failure. Rather, it seems designed to prevent the type of failure that leads to nose-over accidents. But even for that one purpose it is worth it, if it acts as intended.Whether or not this modification would dampen and prevent such an oscillation
I do have one question for the developer: would it be wise to have some rubber-like inserts between your brace and the Van's nose gear? Surely during normal runway/taxiway use the brace must contact (bang on) the NG? So the rubber-like inserts would prevent damage to either brace or NG.
I was thinking it would be interesting to put modeling clay in that space and do some landings to see how much compression happens in normal landings.
It would be hard to keep any dampener in place due to the action multiplier on the part... maybe a molded rubberized fixture that can be replaced at the condition inspection.
This would be completely unnecessary as there is no contact until the gear leg is over stressed. At that point you need to look closely at everything, including landing technique. Allan