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08-26-2015, 09:20 PM
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Join Date: Jun 2007
Location: Atlanta
Posts: 745
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45 psi tire press & all due respect to Walt Aronow
Walt, With all due respect, maybe a month ago, you had advised guys to put 45 psi in their tires. That sounded good to me, so I did it. Then I went down to land on a grass strip. After maybe 4 or 5 landings, all on the same approach,  , I realized I had to go around. When I got back home to my cement runway, I found I was "dancing" all over the runway before I could finally confirm my wheels were solidly planted on the cement. The next time I went flying, and then tried landing at home port, I seemed to be moving sideways even though I knew my wheels where on the cement. I don't normally have problems landing. I think I need to let 5, maybe 10 psi out of my tires. Anyone else notice this? Walt? I'm all ears. 
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08-26-2015, 09:31 PM
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Join Date: Sep 2011
Location: WV22
Posts: 849
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I'm not Walt but, I fly off of a grass strip that at this dry time of year is very rough. Earlier in the season when the ground was still moist, I used +-25lbs and it was a happy medium. Even when landing on asphalt. I've since changed to 35 lbs and while it feels better on pavement, my drought stricken grass runway begs for 25 lbs again.
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RV-4 0320\D3G 160, Whirlwind 200GA 70".
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08-26-2015, 09:43 PM
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Join Date: Oct 2009
Location: Victoria, BC, Canada
Posts: 3,932
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I may bounce 3 or 4 times on an occasional landing, but I haven't yet correlated that to tire pressure or runway surface. I've landed on both pavement and grass with 40lb in the tires with no issues... in fact I find it easier to wheel it on with the higher pressure. YMMV?
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Rob Prior
1996 RV-6 "Tweety" C-FRBP (formerly N196RV)
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08-26-2015, 09:57 PM
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Join Date: Apr 2012
Location: Tampa (BKV)
Posts: 926
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I had the same experience. 45psi is way too much. It's like rolling on a Flintstone wheel which makes complete sense if you speak to a tire manufacturer about what should drive your selected pressure.
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RV-8 Flying
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08-26-2015, 10:58 PM
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Join Date: Jan 2010
Location: Ottawa, Ks
Posts: 2,188
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I run 48 psi in my mains and haven't noticed any issues, I've found I bounce it just as well at lower pressures  .
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RV 7 400 hours and counting
19 donation done
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08-27-2015, 03:47 AM
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Join Date: Jan 2005
Location: Kansas
Posts: 384
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When I was having similar issues after moving my tire pressure up 45psi I found I was flying way too fast on short final, the flare, and even touch down. Once I slowed my approaches down and never letting the airplane touch down until it won't fly anymore my landings are now much better. I do have an AOA system installed with the audio piped into the headset which makes it very easy to safely slow down and feel comfortable. I now find myself watching other RVs on landing and noticing the landing speed vs quality of landing, which I firmly believe supports my initial statement above.
Just my 2¢
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08-27-2015, 05:53 AM
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Join Date: Oct 2005
Location: 08A
Posts: 9,500
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I set 50. Of course, all my landings are above average, like 90% of pilots.
Gents, this has nothing to do with landing ease or ride quality. Running higher pressures means less carcass heating, less tube chafing, less cord strain, less chance of wheel and wheel pant damage, shorter takeoff roll, less tread wear, and probably a few other points I have forgotten right now. I can understand if those with round gear legs must run some particular pressure to kill shimmy; it's an unfortunate crutch, the sort of compromise that sometimes must be made. On an RV-8 with flat gear? Pleeeease....
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Dan Horton
RV-8 SS
Barrett IO-390
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08-27-2015, 06:37 AM
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Join Date: Feb 2011
Location: USA
Posts: 3,179
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I switched from 32-35psi to 45/48psi when I replaced my tires (tyres) and went to 380's.
When I bounce or find the plane side stepping a bit it's all my fault, not the tires. And when I do bounce, I'm much less worried about the wheel pants.
I do think the higher pressure helps a bit with my take off distance.
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08-27-2015, 06:49 AM
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Join Date: Jul 2009
Location: Mojave
Posts: 4,652
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I run 45 in all my airplanes. When it gets hard to push out of the hangar I know it's time to add air. There is a big difference in rolling resistance between 30 and 45.
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WARNING! Incorrect design and/or fabrication of aircraft and/or components may result in injury or death. Information presented in this post is based on my own experience - Reader has sole responsibility for determining accuracy or suitability for use.
Michael Robinson
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Harmon Rocket II -SDS EFI
RV-8 - SDS CPI
1940 Taylorcraft BL-65
1984 L39C
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08-27-2015, 06:59 AM
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been here awhile
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Join Date: Dec 2004
Location: North Alabama
Posts: 4,301
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Quote:
Originally Posted by DanH
<snip>
I can understand if those with round gear legs must run some particular pressure to kill shimmy; it's an unfortunate crutch, the sort of compromise that sometimes must be made. On an RV-8 with flat gear? Pleeeease....
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Distinction does indeed need to be made between RV-6 and RV-4 gear and the other RV models, especially the RV-8. This is not a case of one size fits all.
There is something in either the design or construction of tail draggers with round gear that can excite shimmy at certain speeds. "Solutions" have been discussed for many years (remember the wood stiffeners that were in vogue twenty years ago?) but for many of us running tire pressure less than 35 psi is the only way we have found to dampen shimmy, especially after tires have worn to some degree. This may not be optimum pressure for the tire but is a case where compromise must be made in order to have a plane that doesn't feel like it is trying to shed its gear at certain speeds.
And yes, trying to land a tail dragger too fast often doesn't end well. 
Last edited by Sam Buchanan : 08-27-2015 at 07:05 AM.
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