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  #1  
Old 04-25-2021, 05:01 PM
JDA_BTR JDA_BTR is offline
 
Join Date: Dec 2013
Location: Colorado Springs, CO
Posts: 1,359
Default Landing Gear Puzzle - RV-8

RV-8 slow build. Lining up to drill the gear holes. I can't sweep the legs aft enough to make the leading edges inboard and outboard all line up on the same plane while being able to maintain proper edge distance on the outboard load plate and also at the limit of the aft bolt hitting the fairing z-channel even after relieving a fair amount of the corner.

My best compromise is to sweep aft best I can, ensuring the 3/16" edge distance is on the money laterally, and accept that the legs arent truly square across the entire leading edge.

Doing that, ensuring that the gear distance to tail is same both sides, and distance to a straightedge forward is same as well, I feel pretty confident the axles are going to be very close in position fore and aft.

The other reason I would like to sweep the legs more is for the slight toe-in condition that exists where the legs end up. See in the pics I clamped straight edges to the foot of the leg to measure the toein. A foot aft of the axle the straightedge shows about 5/8" wider a foot behind the axle than at the axle (the two legs are toed-in 2.5-3 degrees). Not sure which is more or less because I don't have the true centerline to measure to up there. I presume I can fix this with shims. I think it will change a bit once the bolts are in and down too.

Am I making the right compromise or am I missing something in my setup?
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Ser 140142, RV-14A flying - N1463
Ser 83825, RV-8 building - N8638?
USN Ret, Urologist, AME, Repeat Offender
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  #2  
Old 04-25-2021, 05:10 PM
D Weisgerber's Avatar
D Weisgerber D Weisgerber is offline
 
Join Date: Sep 2019
Location: Ionia Michigan
Posts: 288
Default

I had the same problem as you, I swept them back as far as I could and still kept the edge distance I needed. I just finished my alignment, I had to install a couple of shims to take out the toe in.
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  #3  
Old 05-03-2021, 07:56 PM
vomatic vomatic is offline
 
Join Date: Mar 2008
Location: Iowa
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JDA-
Did you get it figured out? Have you drilled your holes yet? I spent the weekend doing mine and just got it figured out tonight. I was off by almost 2" at the tail bulkhead when I started. Happy to share pictures if it would help. I'm sleeping on it before I drill just to make sure I'm not missing something.
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  #4  
Old 05-03-2021, 08:27 PM
JDA_BTR JDA_BTR is offline
 
Join Date: Dec 2013
Location: Colorado Springs, CO
Posts: 1,359
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I have mine all drilled now. What I had to accept was that the gear legs are not true across the front top and bottom and will have some camber. But the bolts are all in the right place and the gear legs are both same distance to the tail and true in that respect. I think Iíll be using some shims to have the axles true athwartships later.
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  #5  
Old 05-03-2021, 08:27 PM
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N804RV N804RV is offline
 
Join Date: May 2013
Location: Mount Vernon, Wa
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Quote:
Originally Posted by JDA_BTR View Post
RV-8 slow build. Lining up to drill the gear holes. I can't sweep the legs aft enough to make the leading edges inboard and outboard all line up on the same plane while being able to maintain proper edge distance on the outboard load plate and also at the limit of the aft bolt hitting the fairing z-channel even after relieving a fair amount of the corner.

My best compromise is to sweep aft best I can, ensuring the 3/16" edge distance is on the money laterally, and accept that the legs arent truly square across the entire leading edge.

Doing that, ensuring that the gear distance to tail is same both sides, and distance to a straightedge forward is same as well, I feel pretty confident the axles are going to be very close in position fore and aft.

The other reason I would like to sweep the legs more is for the slight toe-in condition that exists where the legs end up. See in the pics I clamped straight edges to the foot of the leg to measure the toein. A foot aft of the axle the straightedge shows about 5/8" wider a foot behind the axle than at the axle (the two legs are toed-in 2.5-3 degrees). Not sure which is more or less because I don't have the true centerline to measure to up there. I presume I can fix this with shims. I think it will change a bit once the bolts are in and down too.

Am I making the right compromise or am I missing something in my setup?

I was frustrated with lining up the plumb bobs. I went and bought 2 4' carpenter's levels from Harbor Freight and clamped them to the outboard face of the each gear leg with them exaclty on center. With the fuselage leveled and the levels on the gear legs centered and leveled, I measured the distance between the forward and aft ends of the levels. Once I got the distances equal, I dropped a plumb bob off the most outboard point of the leading edge of each gear leg and marked the point on the floor under each gear leg. I also dropped a plumb bob off the tooling hole of the F-812 buckhead and marked its corresponding point on the floor. Then measured from the marked points on the floor from each gear leg to the point marked for F-812. Once I got those three measurements in agreement, I then double checked my dimensions for the outboard wear-plate/bracket set on each leg.

I ended up trimming quite a bit off the Z brackets, so much so that I changed from a double lug nutplate to a single lug nut plate on the aft Z bracket. But, all the numbers worked out to perfection. And, when I went back and dropped the 2nd pair of plumb bobs on the inboard leading edges of the gear legs (per Van's) low and behold, they all lined up, perfectly!
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  #6  
Old 05-03-2021, 08:31 PM
JDA_BTR JDA_BTR is offline
 
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Location: Colorado Springs, CO
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My problem with doing what you described is that the wear plate would end up cockeyed and not have correct edge distances. So I compromised to keep edge distances right knowing I could shim later. But I did make dead sure the legs were swept back as much as I could reasonably do with both legs equidistant from the tail. I also measured them equidistant from the firewall transverse line. Right and left arenít perfect but they are equal. Close enough to let shims fix the small difference.
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Ser 140142, RV-14A flying - N1463
Ser 83825, RV-8 building - N8638?
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  #7  
Old 05-03-2021, 08:51 PM
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Pilot135pd Pilot135pd is online now
 
Join Date: Jan 2019
Location: Vaca Moo Airport - TA37 in East TEXAS
Posts: 1,493
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If you decide to install the stronger gear bolts, let me know. I have a set for both sides plus the wedges so the bolts don't turn and you can check tightness later from the bottom without needing to hold the top of the bolt.
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  #8  
Old 05-03-2021, 10:28 PM
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N804RV N804RV is offline
 
Join Date: May 2013
Location: Mount Vernon, Wa
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Quote:
Originally Posted by JDA_BTR View Post
My problem with doing what you described is that the wear plate would end up cockeyed and not have correct edge distances....

Huh! I didn't have that problem. My wear plates and brackets were proper dimensions. And, the final holes were right where they are supposed to be.

I do have the SkyDesigns Aluminum landing gear. But I can't see how that would've made a difference.

Glad you found a solution! :-)

My problem area seems to be mounting the flap control tube blocks right now. So, I guess that's payback for having an easy time with the gear.
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  #9  
Old 05-04-2021, 07:57 AM
JDA_BTR JDA_BTR is offline
 
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Location: Colorado Springs, CO
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I have the bolts and clips to put in thanks. The aluminum gear legs are quite different so no surprise they are easier to line up. I have the stock steel gear.
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Ser 140142, RV-14A flying - N1463
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USN Ret, Urologist, AME, Repeat Offender
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  #10  
Old 05-19-2021, 03:28 PM
benjam benjam is offline
 
Join Date: Mar 2019
Location: Brisbane, Australia
Posts: 25
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Quote:
Originally Posted by N804RV View Post
I do have the SkyDesigns Aluminum landing gear. But I can't see how that would've made a difference.
Hi Ken.

I too am fitting the sky design gear right now to my QB RV8. Do you have any piccies of the process? I am trying to sort out the instructions for the VANS gear legs verses the skydesign gear, and am not really sure about the plumb bob and alignment setup.

Cheers, Ben
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