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g.hendricks(at)sbcglobal.
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 Posted: Tue Aug 22, 2006 8:00 pm Post subject: YAK-55M Tires |
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Hi All You Yak Experts,
Don’t laugh out there, but I just bought a YAK-55M, having little experience with YAKs & M-14Ps, and am not an A&P. I have read all the manuals, and have tons of questions for which that I’d like to get opinions & answers. So here goes the first installment:
TIRES
1) Tires… The previous owners used retread 400x150 tires from two different US retread suppliers. >From the logs the current set have 64 landings and my judgment says they need changing. The previous set of retreads were changed after only 39 landings. The wear pattern is completely smooth on one half and almost full tread on other half the tire. What’s the usual number of landings you folks are getting out of tires (new or retreads) and what gives with the YAK-55 wear pattern? Is something out of adjustment or is this just the way they wear with spring gear. The book says the tires can be turned around which implies they wear more on one side than the other.
2) New Tires…I decided to start over with tires and bit the bullet for new tires from Desser. I bought Aero Classic 6 ply 400x150 which were the only tires that size I could readily find. When they arrived they seem to be the same as the retreads except they are at least 1.5 inches narrower tread width than the retreads of the same identical size. So what’s the deal with the difference in size ? When I mount them and inflate them…can I expect they will expand to a comparable width…or is there something basic I’m missing about tire sizes ?
3) Tire pressure…The YAK-55M manual says inflate the tires to 3.0 +0.5 KF/CM2, which by my calculation is ~42psi, max 49psi. However, the new Desser 6 ply sidewall data says to inflate to a maximum of 30 psi. There is no inflation data on the sidewall of the retreads. Is this because Russian tires are 4-ply…I tried Desser for an answer and they don’t know.
4) Tail wheel pressure…This airplane has a 200x80 tailwheel with a tube, and the Russian manuals are absolutely silent about inflation pressure. Can’t find any data for a 200x80, but 30 psi seems to be about right…what are the rest of you folks using ?
OPERATING LIMITATIONS
1) The markings for operating limitations on all the instruments are falling off and need replacement, which I thought would be straight forward…not so. The FARs are clear with respect to the airspeed indicator (redline, yellow arc and green arc, etc.), but totally ambiguous wrt to the other instrumentation. After looking at 7~8 cockpit photos of YAK-55s, YAK-52s, and a bunch of Sukhio’s one thing is clear…no two are alike in the way the operating limits are marked.
Anybody want to venture an opinion as to how to properly mark the Oil Temp, Oil Pressure, Fuel Pressure, and Cyl Hd Temp., Etc or is this totally my choice under Experimental – Exhibition ?
Regards,
George Hendricks
N95YK
[quote][b]
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Scooter
Joined: 10 Jan 2006
Posts: 155
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| Posted: Wed Aug 23, 2006 7:20 am Post subject: Re: YAK-55M Tires |
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Sounds like your gear is either toed-in or toed-out. Sometimes this is corrected via a shim between the wheel and the gear. I've bought these for Cessna gear and they sell for ungodly amounts of money - $100 per pair for used shims. From my experience with Cessna spring gear you can push the aircraft forward or backward and see the gear either spreading or coming together.
Where are your tires wearing? Inside or outside? This will tell you if it's toe-out or in. I think they wear on the outside for toe-in and inside for toe-out (someone correct me if i'm wrong).
[quote="g.hendricks(at)sbcglobal."]Hi All You Yak Experts,
Don’t laugh out there, but I just bought a YAK-55M, having little experience with YAKs & M-14Ps, and am not an A&P. I have read all the manuals, and have tons of questions for which that I’d like to get opinions & answers. So here goes the first installment:
TIRES
1) Tires… The previous owners used retread 400x150 tires from two different US retread suppliers. >From the logs the current set have 64 landings and my judgment says they need changing. The previous set of retreads were changed after only 39 landings. The wear pattern is completely smooth on one half and almost full tread on other half the tire. What’s the usual number of landings you folks are getting out of tires (new or retreads) and what gives with the YAK-55 wear pattern? Is something out of adjustment or is this just the way they wear with spring gear. The book says the tires can be turned around which implies they wear more on one side than the other.
2) New Tires…I decided to start over with tires and bit the bullet for new tires from Desser. I bought Aero Classic 6 ply 400x150 which were the only tires that size I could readily find. When they arrived they seem to be the same as the retreads except they are at least 1.5 inches narrower tread width than the retreads of the same identical size. So what’s the deal with the difference in size ? When I mount them and inflate them…can I expect they will expand to a comparable width…or is there something basic I’m missing about tire sizes ?
3) Tire pressure…The YAK-55M manual says inflate the tires to 3.0 +0.5 KF/CM2, which by my calculation is ~42psi, max 49psi. However, the new Desser 6 ply sidewall data says to inflate to a maximum of 30 psi. There is no inflation data on the sidewall of the retreads. Is this because Russian tires are 4-ply…I tried Desser for an answer and they don’t know.
4) Tail wheel pressure…This airplane has a 200x80 tailwheel with a tube, and the Russian manuals are absolutely silent about inflation pressure. Can’t find any data for a 200x80, but 30 psi seems to be about right…what are the rest of you folks using ?
OPERATING LIMITATIONS
1) The markings for operating limitations on all the instruments are falling off and need replacement, which I thought would be straight forward…not so. The FARs are clear with respect to the airspeed indicator (redline, yellow arc and green arc, etc.), but totally ambiguous wrt to the other instrumentation. After looking at 7~8 cockpit photos of YAK-55s, YAK-52s, and a bunch of Sukhio’s one thing is clear…no two are alike in the way the operating limits are marked.
Anybody want to venture an opinion as to how to properly mark the Oil Temp, Oil Pressure, Fuel Pressure, and Cyl Hd Temp., Etc or is this totally my choice under Experimental – Exhibition ?
Regards,
George Hendricks
N95YK
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L39parts(at)hotmail.com
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| Posted: Wed Aug 23, 2006 4:50 pm Post subject: YAK-55M Tires |
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3) Airplane tires have a maximum rated weight and a maximum rated pressure. Get some graph paper and scale it appropriately, then draw a straight line from the point of max weight, max pressure to 0/0. Find your plane's weight on the graph to see what your correct tire pressure.
[quote] ---
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