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pitts_pilot(at)bellsouth.
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 Posted: Sat Oct 31, 2009 5:02 pm Post subject: [Bulk] Align your the gear legs! |
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This is timely. I was having a discussion with an owner of an aircraft
with the tapered rod gear ..... about which is better, toe in, or toe
out. Visualize what happens when the gear leg gets weight on it and the
tire moves outward. The tire tilts inboard. What happens to your
wheelbarrow when the tire does that? It turns in the direction of the
lean. With the dynamics of a landing, when pressure is put on that
landing gear, and it moves out .... it wants to turn under the nose
...... and the weight of the aircraft shifts more to that side. And
the matter gets worse .... and you're now a passenger on a merry go round.
I've given this activity a lot of thought ..... primarily in relation to
my Pitts special. It has spring aluminum gear instead of the bungee
gear. With the aluminum gear, I have none of the tendency to
ground-loop ... it's stiffer than the bungee gear.
I can only assume (yeah, I know!) that the typical wear on the inside of
the RV tires is due to the amount of scrubbing as the tire moves out to
the side in a landing, so the movement is significant. What I've been
talking about is called 'camber' .... not 'toe'. However, I think that
if there is toe-in, the results are going to be the same as I describe.
Since the axle will also move aft due to the way the gear is mounted,
THEN the change in toe-in will increase. So, now we have two
contributions to causing the wheel with weight on it to want to turn
under the nose.
Please find fault in my reasoning here ...... so I don't create a
problem when I drill my gear.
Now this leads to the question about ..... the wooden stiffeners that
the other RV's have been adding to their gear. Any thoughts here???
Linn
do not archive .... speculation in process.
Strasnuts wrote:
| Quote: |
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.
--------
Cust. #40936
RV-10 SB Fuselage
N801VR reserved
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p 70286#270286
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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 6:13 pm Post subject: [Bulk] Align your the gear legs! |
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Ken at Van's stated they shoot for 0 to two degree toe in. Braking will
also pull the gear toe out after landing.
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_________________
40936
RV-10 SB N801VR Flying
780 Hours
SuperSTOL 60 hours |
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dlm46007(at)cox.net
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| Posted: Sat Oct 31, 2009 7:10 pm Post subject: [Bulk] Align your the gear legs! |
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Generally tri gear airplanes have a little toe in; tail draggers have a
little toe out , all for stability. We tried checking alignment on the 10
but results were mixed. On my Glastar the factory procedure resulted in 3
degrees toe in per side when they stated that they wanted 1/3 of a degree
toe in. Fixing the problem involved hanging the aircraft on jacks and using
a magnetic laser attached to each wheel outboard. A line was shot to the
tail area where a plumb bob line was intersected. We rotated the legs in the
socket until a rectangle was formed by the laser shots and the line at the
tail and between the main gear. We then redrilled and upsized the gear bolt
to lock in the new toe in. it was almost zero; perhaps as much as 1/2 degree
toe in. We had a retired automotive suspension engineer consulting with us.
The result on the Glastar is that the sides of the tires are not being
scrubbed off by landing and taxiing. If the 10 tires exhibit the same
characteristics we will address the 10 the same way.
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jim(at)CombsFive.Com
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| Posted: Sun Nov 01, 2009 5:33 am Post subject: [Bulk] Align your the gear legs! |
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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-------------------------------------------------------------------------------------> RV10-List message posted by: Linn Walters <pitts_pilot(at)bellsouth.net>This is timely. I was having a discussion with an owner of an aircraftwith the tapered rod gear .... about which is better, toe in, or toeout. Visualize what happens when the gear leg gets weight on it and thetire moves outward. The tire tilts inboard. What happens to yourwheelbarrow when the tire does that? It turns in the direction of thelean. With the dynamics of a landing, when pressure is put on thatlanding gear, and it moves out .... it wants to turn under the nose....... and the weight of the aircraft shifts more to that side. Andthe matter gets worse .... and you're now a passenger on a merry go round.I've given this activity a lot of thought ..... primarily in relation tomy Pitts special. It has spring aluminum gear instead of the bungeegear. With the aluminum gear, I have none of the tendency toground-loop ... it's stiffer than the bungee gear.I can only assume (yeah, I know!) that the typical wear on the inside ofthe RV tires is due to the amount of scrubbing as the tire moves out tothe side in a landing, so the movement is significant. What I've beentalking about is called 'camber' .... not 'toe'. However, I think thatif there is toe-in, the results are going to be the same as I describe.Since the axle will also move aft due to the way the gear is mounted,THEN the change in toe-in will increase. So, now we have twocontributions to causing the wheel with weight on it to want to turnunder the nose.Please find fault in my reasoning here ...... so I don't create aproblem when I drill my gear.Now this leads to the question about ..... the wooden stiffeners thatthe other RV's have been adding to their gear. Any thoughts here???Linndo not archive .... speculation in process.Strasnuts wrote:> --> RV10-List message posted by: "Strasnuts" <sean(at)braunandco.com>>> 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 an! d !> 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.>> --------> Cust. #40936> RV-10 SB Fuselage> N801VR reserved>>>>> Read this topic online here:>> http://forums.matronics.com/viewtopic.php?p 70286#270286>>>>>>>>>>>> [quote][b]
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