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Scott & David,
I don't know if you all have ever calculated the weight on the mains when at full gross but I don't believe that you have. It is certainly over 500 lbs. My calculations show that I have 790 lbs on the mains when at full gross versus 413 lbs when empty.
At this weight, I take off at about 90 mph. I try to keep 50 psi in the tires. The Desser's haven't blown up yet.
Here is the screen dump of the spreadsheet showing my numbers.
N31161 Gross Gear Weights.jpg
Here is the spreadsheet itself so that you can calculate your own weight. I didn't calculate the last numbers. I would have had to think for more than 5 minutes. I just iterated the 324 lbs until I equaled 65.60 as the bottom arm.
Lorn
On Mar 17, 2010, at 6:01 AM, Lancair Mailing List wrote:
From: Sky2high@aol.com
Date: March 16, 2010 11:58:44 PM EDT
David,
There are only two tires that I know of that are used on the 300 series aircraft - The Cheng (Chin,Lamb) and the Desser (11-400 for 5" wheels). The Cheng tires are 8 ply rated, max 90 psi and clearly marked "Not for Highway Use" and that implies some speed limitation. The Dessers are also 8 ply rated and marked for a max speed of 68 mph. Interesting about the Desser testing results, what were the Chin (Cheng, Lamb) test results, if any?
My personal experience so far is that the Desser is a better wearing tire than the Chin. That's covering about 80 mph touchdowns with 450 lbs on each main at 1 G. (I wish I always made 1 G landings).
What are options other than these two tires?
What does the Legacy use for a nose tire?
Scott Krueger
11/400-5 8 PLY AERO CLASSIC (NEW VERSION) Unit Price In Shopping Cart 39.95 New 2008 Design! 2 Groove, Wide Rib. Designed For Aircraft Loads and Speeds. Posted for David Sterling <dmsterling@cox.net>:
A couple of months ago I talked to Justin at Lancair about the Desser tires. As far as I am concerned their load and speed rating are not acceptable for the nose gear of a legacy. They were designed for the LSA aircraft. The load and speed rating is actually below what a legacy nose tire is subject to.
Justin contacted Desser tires and got the test results for that tire. They tested the tire to 502 pounds at only 70 mph. The tire failed at 110 mph but only at 325 pounds. Justin said that lancair has contacted Desser tires requesting they manufacture a tire with a higher ply rating.
If you are using this tire for the main tire of a 360 the problem is even worse as far as stress on the tire goes.
Hopefully Desser tires will manufacture a tire that comes closer to what we need.
David Sterling
Lancair Legacy
Race 8
--
Lorn H. 'Feathers' Olsen, MAA, ASMEL, ASES, Comm, Inst
DynaComm, Corp., 248-345-0500, mailto:lorn@dynacomm.us
LNC2, FB90/92, O-320-D1F, 1,700 hrs, N31161, Y47, SE Michigan
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