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Let me preface this with the statement that I have the utmost respect and admiration for Vans and their products and methods.
That said, it would have been fun to be a fly on the wall when they discussed tires, tubes and wheels. On the one side, they looked at what we wound up with in our kits, the cost being about $651 for the RV 12, vs a huge list of tires, tubes and wheels that were probably as strong, as light, and as good a choice, for probably somewhere in the $30 to $60 range for the whole plane! I have not checked to see what other kit makers have used to reduce costs. |
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Aviation is plagued by two different issues.....
- The cost of liability and - The cost of low volume production Put these two together and it makes prices of aviation parts seem ridiculous when compared to Walmart. Van's has not become the premier kit aircraft seller in the world by ignoring opportunities to reduce cost. Just the opposite. If the notion that a tire is a tire (regardless of who made it and where it was purchased) was true, then I guess it would be true for engines also, and we would all be flying RV's with an engine that came out of a wrecked car..... P.S. I would be curious to take a look at the complete set of wheels, brakes, and tires that could be bought for only $60 to put on an RV-12. A complete set of just tires for my riding lawnmower (from Walmart) would cost a minimum of $120. |
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The other kits with which I am familiar use wheels and tires from many of the same vendors Vans uses. These are safety-critical items that no kit manufacturer (or pilot!) wants to see fail. Less expensive wheels are pretty much limited to ultralights (and wheelbarrows....) and most will not accommodate brakes. I don't think many builders would want those wheels and tires on their RV-12..... ;) |
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This is what keeps the big guys in check. What do you think a G3 would cost (if it was even available) if the likes of Dynon, MGL, GRT, et. al. couldn't enter the marketplace? |
Part of the problem is old age. At 80 it still seems like a new car should be around $1500 yet, whatever happened there?
I got my new tube from Vans today and was surprised to actually see something written on it, never seen that before. Now this looks like maybe one that will not leak - at least not so badly. [IMG] [/IMG] |
About half of 10 or so Leakguard tubes I've installed in the past 12 years lose about 10 psi over the course of a month after being inflated to 50 psi. The better ones only lost 3 or 4 psi.
On the Michelin Airstops I just installed new this past July, I just added 10 psi today to each to bring them back up to 50 psi. It would be great to go a year without having to add air, but doesn't seem likely. |
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I've always found the Michelin's to leak far less than the Leakguards - and the Michelin's only cost a couple of bucks more (last time I checked). |
Wow that is bad. Now I am unsure if I want to change out the tubes to the new one, might even be worse than what is in there!. It would not be so bad if I could get down on the floor, roll the aircraft around to align the valve stem, then fish thru the hole to check pressure and add air.
Getting old sure sucks. air.QUOTE=alcladrv;1214491]About half of 10 or so Leakguard tubes I've installed in the past 12 years lose about 10 psi over the course of a month after being inflated to 50 psi. The better ones only lost 3 or 4 psi. On the Michelin Airstops I just installed new this past July, I just added 10 psi today to each to bring them back up to 50 psi. It would be great to go a year without having to add air, but doesn't seem likely.[/quote] |
I have had many of the newer Leakguard Butyl tubes simply fail outright over the last 3 years (One hasn't gotten truly religious until one lands a Pitts S-1 with a flat main in tight wheelpants). Butyl rubber is not natural rubber. It is a synthetic rubber with the advertised advantage of being impermeable to air. Unfortunately since it is a synthetic it is basically molded similar to plastic. You can see the mold lines on the surface of the Leakguards. These mold lines are where we have found many failures of the Leakguards. So while they don't leak sitting in the hangar, they do completely fail when one of those mold lines chafe on the inside of the tire. Natural rubber does not do that. I try to avoid Leakguards. I don't have a problem with natural rubber as long as I check pressures regularly. I think the big push toward Butyl tubes has more to do with their being cheaper to produce as much as anything. And you gotta hand it to the marketing guy who thought up charging more for cheaper stuff. Brilliant.
I am glad to hear that Michelin Airstop tubes are having better success that Leakguard. I will try some Michelins next. Here are some pointers with respect to the synthetic Butyl tubes: 1. If installing Butyl inner tubes use even more talc powder than traditional amounts. This will help with the chafing failure rate we have seen rearing it's head recently. 2. Make sure your baby powder or tire powder is in fact "talc" and not cornstarch. Most of the cheap generic brands are cornstarch. Cornstarch is made of larger particles than talc and cornstarch is hygroscopic meaning it absorbs moisture from the air. This gives it a propensity to get clumpy and sticky over time instead of dry and smooth which might be a contributing factor in the mold line chafing. Talc is made of smaller particles of clay and minerals and while it too can absorb a certain amount of moisture from the air that doesn't cause it to get sticky like cornstarch. 3. Check the air pressures in Butyl tubes often and keep pressures on the high side to minimize chafing. Low pressures exacerbate the chafing. Of course now you will be checking pressures as often as with natural rubber tubes. I think. Jim |
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