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Strasnuts
Joined: 10 Feb 2009 Posts: 502 Location: Salt Lake City, UT
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Posted: Sat Oct 31, 2009 4:12 pm Post subject: Align your the gear legs! |
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I finally got to a point where I could mount my landing gear legs. I spoke with Scott Schmidt about the alignment issues he has had with his gear. He has a main gear shimmy while decelerating through 30 knots. He has tried changing tire brands and balancing the wheel. He has also told me that his gear leg might be toed out.
When I mounted mine yesterday, it was obvious the left gear was toed out and the right gear was toed in (visually). I called Van's and spoke with Ken. He said they had no issues in the past but that doesn't mean they're not wrong. We also wanted more proof than a visual check. which I can't blame him. I called Scott and he came over to see it and brought his giant man brain with him. We pulled some lines off of the gear and axles to check alignment and confirmed they were way off. What I ended up doing was making each side toed in. The right one lined up with the factory hole and came out at 1.33 degrees toed in and 7 degrees camber with no weight on the axle. I also measured to a point on the tail from the axle. On the left I could visually see the factory hole was off. Keep in mind that barely off by less than a 32nd is a huge change on the axle both camber and toe in. It was amazing how far off the factory hole was. I tack welded the top of the gear mount and gear leg together so they wouldn't move while I drilled a new hole. I used a tapered reamer which only made the first gear mount hole oval. I then reamed the new gear mount hole, gear leg and made the new opening on the other end of the mount. It didn't oval the backside gear mount hole since it is undersized to begin with. I used the factory bolt, AN5-24A, which felt great. I can't imagine it will move with the four weld tacks on the top and the other parts being snug. I now have two gear axles that are the same toe in and camber. It also made the measurements within a 1/16th which I made from the axle to a point on the tail. I don't know if the gear legs are drilled wrong at the factory or the gear mount holes are off.
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_________________ 40936
RV-10 SB N801VR Flying
780 Hours
SuperSTOL 60 hours |
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Ron B.
Joined: 17 Feb 2009 Posts: 103 Location: Nova Scotia
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Posted: Sat Oct 31, 2009 4:43 pm Post subject: Re: Align your the gear legs! |
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I'm by no means an expert. I don't think the tack weld is a good idea. With all the flexing the gear is going to experience , the mount needs to be able to move. I'm thinking of a car frame. It's riveted and bolted together so it can move a little. A friend was rebuilding a frame and welded it together and later had cracks. I know it's bolted together also, but it sounds like the hole is oval and you are relying on the tack welds. Please check this out with someone that knows.
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Strasnuts
Joined: 10 Feb 2009 Posts: 502 Location: Salt Lake City, UT
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Posted: Sat Oct 31, 2009 4:50 pm Post subject: Re: Align your the gear legs! |
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The tack welds are just there to hold it while I ream the hole. It is still really close to the original holes plus it is just one side of the gear mount hole that was affected. If I get more negative feedback, I will barely oversize the entire hole and get a new bolt and grind the tack welds off.
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_________________ 40936
RV-10 SB N801VR Flying
780 Hours
SuperSTOL 60 hours |
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pitts_pilot(at)bellsouth. Guest
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Posted: Sun Nov 01, 2009 5:52 am Post subject: Align your the gear legs! |
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Good point Jim! I like the 'in theory' part <GR>! I'm using an old CD
and a plastic pen I bent to simulate the gear and it's movement .....
and forgot about braking. I really spent a lot of time trying to figure
out how to mount spring gear on my -10 and finally gave up. We've
talked ab out the 'deficiencies' of the tapered rod design .... mostly
aesthetics ..... but the pluses if being simple and easy to install
outweigh them. And the main gear mounts don't have to be re-designed
..... a problem with hand-me-downs to the 'youngest kid'. Although, I
don't know for sure that the mounts weren't re-designed.
Linn
Jim wrote:
Quote: | One will also need to factor in the angle of the fuselage at touchdown
(Nose High - In theory!)
I would real interesting to video the motion of the wheel during a
landing (Without the wheel fairing attached.
Jim C (N312F)
Do Not Archive
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jim(at)CombsFive.Com Guest
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Posted: Sun Nov 01, 2009 8:41 am Post subject: Align your the gear legs! |
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We have 130 hours on the -10 (Our first year) and the first condition inspection is about 6 weeks away. Tires are showing wear on the outside after about 200 landings. Both sides have wear, but not entirely even (Pilot side is worse). I do have some shimmy as well on the landing roll out too. Usually releasing any brakes stops it. Shimmy is not always there. I have played with the nose wheel but I am beginning to think it's the mains. I have thought about mounting a camera on the belly just to see what is going on as well as to take some interesting videos.Since I will be removing the wheels for the inspection, I will be checking the axle alignment. Just curious.Jim C (N312F)Do Not Archive-----------------------------------------------------------------------------------------------------------------------> RV10-List message posted by: Linn Walters <pitts_pilot(at)bellsouth.net>Good point Jim! I like the 'in theory' part <GR>! I'm using an old CDand a plastic pen I bent to simulate the gear and it's movement .....and forgot about braking. I really spent a lot of time trying to figureout how to mount spring gear on my -10 and finally gave up. We'vetalked ab out the 'deficiencies' of the tapered rod design .... mostlyaesthetics ..... but the pluses if being simple and easy to installoutweigh them. And the main gear mounts don't have to be re-designed...... a problem with hand-me-downs to the 'youngest kid'. Although, Idon't know for sure that the mounts weren't re-designed.LinnJim wrote:> One will also need to factor in the angle of the fuselage at touchdown> (Nose High - In theory!)>> I would real interesting to video the motion of the wheel during a> landing (Without the wheel fairing attached.>> Jim C (N312F)>> Do Not Archive [quote][b]
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scottmschmidt(at)yahoo.co Guest
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Posted: Sun Nov 01, 2009 10:47 am Post subject: Align your the gear legs! |
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I spent some time at Oshkosh talking to Van about the gear legs. He was very candid with me about the design. The tapered gear leg is not optimal as he mentioned but it is easy to manufacture and inexpensive to produce. He has heard of other RV-10's with shimmy in the gear legs but was not sure how toe-in effected it.
The good news is that there are many RV-10's out there that have no shimmy. I flew Tim's plane and his plane worked perfectly as do many others.
When Sean installed his gear legs I was surprised how little movement it took to drastically change the toe in on the gear which made me very optimistic that I will be able to adjust mine.
Ken Kruger said there is no issue installing a larger bolt into the gear leg if needed.
Let me share my observations. I can feel the shimmy during the taxi phase but not on takeoff. The only time I feel it on landing is when I transition through 30mph.
Holding the nose off as long as possible can eliminate the shimmy (which causes effective toe-in) as well as not braking through the 30mph zone.
I am in the middle of my annual and this week I plan on measuring the toe-in as it sits on the ground and suspended. Depending on what I find there I will determine what adjustments need to be made.
Van mentioned the idea of stiffening the gear with wood but I am not even going to consider this knowing there are many planes that do not have any issues. I wish the gear was shaped like the RV-8 or Cirrus, that would completely eliminate this issue.
I wish I knew about this earlier like and worked on it like Sean did. I told Sean that he could drop the rudder since his plane is going to track so straight.
I'll make sure to post my findings and results.
Scott Schmidtscottmschmidt(at)yahoo.com
From: Jim <jim(at)CombsFive.Com>
To: rv10-list(at)matronics.com
Sent: Sun, November 1, 2009 8:38:57 AM
Subject: Re: Align your the gear legs!
We have 130 hours on the -10 (Our first year) and the first condition inspection is about 6 weeks away. Tires are showing wear on the outside after about 200 landings. Both sides have wear, but not entirely even (Pilot side is worse). I do have some shimmy as well on the landing roll out too. Usually releasing any brakes stops it. Shimmy is not always there. I have played with the nose wheel but I am beginning to think it's the mains.
I have thought about mounting a camera on the belly just to see what is going on as well as to take some interesting videos.
Since I will be removing the wheels for the inspection, I will be checking the axle alignment. Just curious.
Jim C (N312F)
Do Not Archive
---------------------------------------------------------------------------------------------------------------------
--> RV10-List message posted by: Linn Walters <pitts_pilot(at)bellsouth.net>
Good point Jim! I like the 'in theory' part <GR>! I'm using an old CD
and a plastic pen I bent to simulate the gear and it's movement .....
and forgot about braking. I really spent a lot of time trying to figure
out how to mount spring gear on my -10 and finally gave up. We've
talked ab out the 'deficiencies' of the tapered rod design .... mostly
aesthetics ..... but the pluses if being simple and easy to install
outweigh them. And the main gear mounts don't have to be re-designed
...... a problem with hand-me-downs to the 'youngest kid'. Although, I
don't know for sure that the mounts weren't re-designed.
Linn
Jim wrote:
Quote: | One will also need to factor in the angle of the fuselage at touchdown
(Nose High - In theory!)
I would real interesting to video the motion of the wheel during a
landing (Without the wheel fairing attached.
Jim C (N312F)
Do Not Archive
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[quote]
[b]
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