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Jerry,
The outback gear has two things going against it. It has pronounced camber to bump out over the larger wheels while, at the same time, being structurally much less stiff than the original( http://www.n91cz.com/VideoClips/WiggleTest.wmv). The local flow over the door exerts a large down force that the structure could not resist. The doors were simply twisting under the load. The net effect was that the trailing edge of the door deflected downward as a function of IAS. I have seen this in photos of many outback installations, but the video gets you in much closer to the action.
The solution was to go back to a three piece door design. In this way the door sections are not cantilevered nearly as much and part of the load is now carried by the gear leg. In addition, the inner gear door now has a much improved (smaller) moment arm. Its upward force assisting the middle door is now about twice what it used to be. I also switched from glass to carbon as much of the middle door hangs well behind the four attach points on the gear leg.
The impetuous for the change is that the doors were a source of tremendous drag. Switching out the first door yielded a 2 kt improvement in cruise speed. I have yet to install the second side. The parts are done, but a hangar move has delayed the installation.
Chris Zavatson
N91CZ
360std
From: Jeremy Fisher <jffisher@gmail.com>
To: lml@lancaironline.net
Sent: Tue, January 19, 2010 4:49:34 PM
Subject: [LML] Re: AIrcraft video
Chris,
That is quite a change. Can you please describe how you fixed the problem, for those of us who are going to face the same issue? Thanks.
Jerry Fisher
On Tue, Jan 19, 2010 at 2:57 PM, Chris Zavatson <chris_zavatson@yahoo.com> wrote:
Isaac,
Isn't technology great! I used a Sony Webbie to investigate and resolve the problem of 'outback' landing gear doors on the 360 being pulled open in flight.
It is amazing what is happening out there that we can't see.
http://www.n91cz.com/Outback-Gear/OriginalDoor1.wmv
and the fix
http://www.n91cz.com/Outback-Gear/NewDoor1.wmv
Chris Zavatson
From: Isaac Heizer <ijheizer@comcast.net>
To: lml@lancaironline.net
Sent: Tue, January 19, 2010 3:19:02 AM
Subject: [LML] AIrcraft video
For anybody interested in videoing what's going on under and around their aircraft in flight, I suggest helmet mounted cameras fit the bill perfectly. In particular, i temporarily mounted a 4oz, fully self-contained & weather-resistant, video camera to my rear tie-down ring socket to see what my landing gear is doing. The camera can be had for less than $300, and is the ContourHD from www.vholdr.comSample video (mine) is at http://www.youtube.com/watch?v=sShijby0JQU Should be great to see what gear doors are doing, for instance.
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