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  #31  
Old 10-10-2018, 02:50 PM
Dan Langhout's Avatar
Dan Langhout Dan Langhout is offline
 
Join Date: Mar 2008
Location: Huntsville, AL USA
Posts: 456
Default Tire Modeling

Quote:
Originally Posted by DanH View Post
. . . . . . . . I'm not trying to tell you lower pressures won't work. I am telling you tire pressure is an engineered value, not a random pick. . . . . . .
I absolutely agree with this statement. Of course the engineered value is a function of the design criteria.

Do you happen to know how the tire deflection vs load at a given tire pressure is being calculated? I'd be interested in how that is being modeled in the spreadsheet. Or you could just send me the spreadsheet . . . . .
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  #32  
Old 10-15-2018, 05:02 AM
Capt Capt is offline
 
Join Date: Feb 2017
Location: Australia
Posts: 219
Default

I've never seen so much written about just tyre pressures! In near 40 yrs of driving planes (little ones) I've always run around 35 psi, it's not rocket science, tires are a flexible medium, very resilient and designed to take punishment, the only main variable effected by under or over inflation is the amount of wear. I consider tires a consumable item, I keep my RV8 at 35 psi but am not too concerned if it's 10 psi either side.
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  #33  
Old 10-15-2018, 10:11 AM
jpowell13 jpowell13 is offline
 
Join Date: Nov 2008
Location: Baton Rouge, LA
Posts: 574
Default Flats

I've had two flats on roll out on my 6A in about 500 hours of flying. Both times it was on the left main, and I found a pin hole in the outer sidewall area of the tube.

The landings were no big deal, but getting the plane off the runway is a problem if you don't have some good help. Both times it had been a few months since pressure was checked and the tire was probably in the 30 lb area.

When I land at my home airport (Baton Rouge), I always request 4R/22L if available because the idea of shutting down one of the main runways due to a flat worries me. John
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  #34  
Old 10-15-2018, 11:37 AM
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JonJay JonJay is offline
 
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Location: Battleground
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Default

Quote:
Originally Posted by jpowell13 View Post
I've had two flats on roll out on my 6A in about 500 hours of flying. Both times it was on the left main, and I found a pin hole in the outer sidewall area of the tube.

The landings were no big deal, but getting the plane off the runway is a problem if you don't have some good help. Both times it had been a few months since pressure was checked and the tire was probably in the 30 lb area.

When I land at my home airport (Baton Rouge), I always request 4R/22L if available because the idea of shutting down one of the main runways due to a flat worries me. John
Make sure you use ample talc powder when servicing your tubes and tires. I cover the entire tube and inner walls of the tire. Talc sticks to any exposed rubber easily. Once I have a light dusting, any unreasonable excess is removed.
There have been many reports of tube sidewall pin holes. Not sure what the cause but it doesn't seem to be tire pressure related based on the reports I have read here.
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  #35  
Old 10-15-2018, 11:49 AM
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Raymo Raymo is offline
 
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Location: Richmond Hill, GA (KLHW)
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My data point.

I was running 35 all around and tires were wearing well. Landed one day and the taxi back felt very odd. The front tire was flat; hole in the sidewalls of the tube and the tire (Michelin) was eaten up inside from sidewall flexing.

I now run 40-45.
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  #36  
Old 10-15-2018, 02:25 PM
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schristo@mac.com schristo@mac.com is offline
 
Join Date: Sep 2007
Location: WA
Posts: 958
Default -7 Whittman gear moves all over...

I have been running 50 psi in Good Year Flight Special II tires for a bit. These have been great tires so far. Wheel landing with them at these pressures works best when carrying enough speed in the flare to keep the tail up. If the tail is dropping in the flare there can be more rebound than desired if you don't catch the transition on the money. Three point landings need to be very close to stall to limit bounce back.
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  #37  
Old 10-15-2018, 04:06 PM
Simon Hitchen Simon Hitchen is offline
 
Join Date: Apr 2006
Posts: 240
Default Talc

Jon jay, Iíve got a friend of mine who worked for Michelin tires for decades. He came round as i was changing a tire last week and saw me using a bit of talc. His expert opinion was that only the faintest bit of talc was needed because any more than that and with any moisture it clumps up into tiny balls that will rub pin holes in the inner tube. This may answer your question.

Seems plausible.
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  #38  
Old 10-15-2018, 05:57 PM
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JonJay JonJay is offline
 
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Location: Battleground
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Quote:
Originally Posted by Simon Hitchen View Post
Jon jay, I’ve got a friend of mine who worked for Michelin tires for decades. He came round as i was changing a tire last week and saw me using a bit of talc. His expert opinion was that only the faintest bit of talc was needed because any more than that and with any moisture it clumps up into tiny balls that will rub pin holes in the inner tube. This may answer your question.

Seems plausible.
Interesting. I have never found any moisture or clumps, nor any pinholes.
I don’t leave excess talc, just enough dusting to where the rubber dulls. The talc sticks to the raw rubber in a fine coat.
At this point, I think I will keep doing what I have been doing and as I was taught by my dear departed AP/AI. I have had good luck in both tire and tube wear, but I am certainly no expert, just one dumb guy who only knows what he was taught, wrong or right.
Thanks for the input though.
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  #39  
Old 10-15-2018, 06:17 PM
Boyd Birchler Boyd Birchler is offline
 
Join Date: Sep 2014
Location: IN
Posts: 160
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46 years of using talc on many hundreds aircraft tires. I have never seen any adverse effects even though I did not use it sparingly!
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