"A"-front gear optimizations, a summery (with pictures)

Front gear optimizations, with pictures!

I do not want to start the “I make perfect landings every time, so I do not need any margin in my landing gear” arguments again. I simply made a summary of the mods/alterations that I made to my nose gear, because I think these may, one day, save my bacon.
As most of you are aware, the A-models are quite vulnerable to nose gear damage or even “flips”. Actually I found 68 accidents of this nature on the internet. I know I am not a perfect pilot, so I just need some more margin in the nose-gear design. This is the things I did to try to improve and give me just that tiny bit more margin, if ever possible.

From the forums I learned that the following problems may (will) occur:

•Run into a hole/indention on the (grass) runway or taxiway and “digging in” of the gear nut.
•Oscillations of the landing gear during taxi/roll out, due to friction of the front wheel.
•Oscillations of the landing gear during taxi/roll out, due to surface conditions.
•Complete stopping of the front wheel due to “grabbing of the tire” to the fairing.
•Complete stopping of the front wheel due to a flat tire.
•Bouncing due to hard landing.

This is what I did:

•In case the front gear hits a hole/indentation on the runway or taxiways, the fairings should act as a skid. Never operate your a-model without front wheel fairing! To make the fairing more of a skid, I beefed it up with a layer of epoxy and glass, even a couple of layers inside the cone. Also used 8 screws instead of 6 for the connection of the cone to the rear half of the fairing and used 1 size larger screws.
•To make sure the “nut” cannot “dig in” I made a “skid shoe” of the cone of the fairing, by means of epoxy and glass fibers, that was molded to the gear leg nut and fork.
•To avoid hitting the hole, with the fairing, in the first place, I installed the fairing about 3/4 “ higher to get much more clearance at the bottom.
•In case of a flat tire (occurring during takeoff or after, because I would obviously not take of f with a badly inflated tire!) the clearance of the wheel pant has to be enough to guaranty that the tire will not “ grab” the fairing.
•To cope with oscillations, I installed a wooden stiffener to the gear leg. It is made from the lightest wood I could find (at the local DIY store), glassed over to make it immune to moisture and glued to the gear leg with RTV. It is not to make the gear leg stiffer, but merely to dampen (or damp) the up- and down movement of the gear leg. In case it does not work the way I think it will, it can be removed a lot easier than if it was “glassed”, as per VANS instructions.
•Before installing the front wheel, I stretched the fork with a car-jack, to make sure there was no pre-tension on the bearings. I cut-off one lip of the bearing seal (as per the manufacture instructions ), to make sure the wheel is running freely. Also I “staked” and “notched” the mushrooms so the bearing races will not turn on the axle or the mushrooms. (BTW, the axle spacer mod came out just a little late for me, but I think my set-up will be similar to the result that one would get with the axle spacer).
•To avoid oscillations I had the wheel and tire dynamically balanced.
•To avoid shimmy the break-out force is set at 22 lbs

The following pictures will explain a bit more:

Opened up the fork, staked and notched the mushrooms and cut one lip off the bearing seals:



Beefed up the fairing.



Installed a wooden gearleg stiffener:



3/4 additional ground clearance:



Enough clearance, even with a flat tire!



Most important: I made a skid from the front cone of the wheel fairing, to embed the gear nut, so it can not dig in.:



Regards, Tonny.

Looks like some worth while mods to me. I really like the extra fiberglass in the front of the wheel pants. IMHO this is where the "problem" lies. If that nut digs in the ground it's all over. The extra "skid" may allow it to recover, hopefully.

I also like the stiffener. They seem to work good on the mains. The RTV would allow it to flex if needed, but still dampen vibrations. Good idea. Let us know how that feels.

A good landing and "holding the stick back" is still worth mentioning as a preventative for nose wheel issues.

Good work Tonny!!

Given that I am one of the 68 unfortunate souls, I hope everyone reads your post and follows the sage advice.

You said: "(BTW, the axle spacer mod came out just a little late for me, but I think my set-up will be similar to the result that one would get with the axle spacer)."

Using an air conditioning steel spacer I machined on my grinder to fit, my front wheel spins freely no matter what the fork or seals try to do or even if you overtighten the bolt. It's been 140 hours since I bent the gear, hundreds of landing, and the wheel spins as freely as the day we installed the spacer.

Front wheel pant? Never leave home without it!!

I had my very first "nasty" landing just a few nights ago when I hit a wind sheer and the plane just came down far faster the anticipated it. I tried to recover but not quick enough and landed on the main and bounced on the nose gear and before a second bound I was on the go around. It gave me a quite a scar mostly about the nose gear but all was OK.

I guess I am sharing the story just to show how mindful of the limitation of the nose gear I am. I installed the Matco axle mod just a couple of weeks ago which replaces the mushrooms and I already like it very much. I thought about the wooden stiffener but somewhat hesitant since I think it would transfer more of the force to the welded portion of the engine mount where the gear leg is welded to the engine mount. Other then that, I like your mods.

Sorry to hear of your mishap!

Bavafa said:

I had my very first "nasty" landing just a few nights ago when I hit a wind sheer and the plane just came down far faster the anticipated it. I tried to recover but not quick enough and landed on the main and bounced on the nose gear and before a second bound I was on the go around. It gave me a quite a scar mostly about the nose gear but all was OK.

I guess I am sharing the story just to show how mindful of the limitation of the nose gear I am. I installed the Matco axle mod just a couple of weeks ago which replaces the mushrooms and I already like it very much. I thought about the wooden stiffener but somewhat hesitant since I think it would transfer more of the force to the welded portion of the engine mount where the gear leg is welded to the engine mount. Other then that, I like your mods.

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Feel free to give me a call or email. If I can help anyone avoid the indignity, expense, and utter frustration of breaking their project, I will.

Virtually every improvement we made to project airplane #1, the 9A, is going into project airplane #2, the 6A. It will not fly until the wheel pants are on and my two partners have agreed not to fly until they get lots of transition training.