install pics: Leg fairing alignment

[dhall_polo]

Van's directions are ok, but a few pics and words might save anyone about to do this some head scratching.

I marked 3 points on the leading edge of the leg fairing and hung a plumb bob from each to mark the distance from the centerline. I also noted the height of each point above the ground. I then marked those 3 points on a board which was clamped to a shop stool. Each point on the board is the same distance from centerline and height above ground as the points I marked on the fairing. I put a staple at each point and ran string to it's corresponding point on the leg. It was necessary to tape the string on the leading edge to keep the string from slipping down. Now each string is pointing straight back, parallel to centerline.

Using a ruler, I measured the distance between strings and tweaked the trailing edge of the fairing to split the difference. (this shot is from the ground looking up the leg to the cowling.) Now it's safe to clamp in place and inject foam.

 

[TGRV7]

Progress....

Please keep going on the install narrative and pics
Thanks

 

[dhall_polo]

more stuff on my builder site.

I have some more pics for this stage of construction on my builder site, linked below. I'm still working away at it. Posting pics was a nice diversion from all the dust and sticky goo messes.

rv7.donka.net - fairing installation

Another good thing I'll take a pic of on the wheel pants is how I lined that up. Setting the wheel pant into position was a wobbly adventure to be sure. I didn't have the camera ready when I did the first. I ended up making good use of "rope lighting" and a laser to help with the positioning and drilling. Pics on that coming up.

Don

 

[BillSchlatterer]

Great Foam ??

Don, is Great Foam the only thing you are using to hold the fairing in place. Did you use some kind of release agent so that you could remove the fairing later if need be.

Is that just for the initial set and then you are using something else to make the fit more permanent. Will you be using the wood stiffeners? If so, how to they work in this install?

Thanks Bill S
7a about the same spot

 

[vlittle]

This method was originally publised in the RVAtor, but I don't remember if they published all of my photos.

One thing I did was pin the top and bottom of the fairings with 3/32 dowels (even pieces of hinge pins will work). I had the wooden stiffeners so this worked fine. Van's suggested that even a couple of small wooden blocks epoxied to the gear legs would work.

Now, whenever the fairings go on, I pin them in place to get the proper alignment. I usually remove the pins after the clamp is tightened at the top, and the intersection fairing on the wheel pant keeps the bottom aligned.

FMI: http://www.vx-aviation.com/rv-9a/Tips.html

 

[TGRV7]

keep em coming

Merry Xmas

 

[Mike Ice]

great foam

Don,

Thanks for the pictures and ideas.

I know someone else asked if the foam was all you were going to use to keep the fairings in place but i did not see an answer. The foam seems like it would be enough to me but what is your response? Has this been discussed before in the forums?

Have you or anyone else ever considered drilling a hole or two in the middle of the fairing, underneath, and spraying in the foam from there, instead of from the ends?

Mike Ice

 

[striplic]

Seal the Deal? Strengthening in general!

Aren't the leg fairings only to be secured by the hose clamp at the top of the gear leg and the fairings float/slip (up/down a bit) inside the lower intersection fairing as the gear leg flexes on landing. Would sealing at the bottom inhibit this as well as make difficult removal sometime in the future. Evidently foaming is being done by some. I would be interested to hear how the parts are holding up in use. Are rivets working loose from the hinges or rivet holes in the glass wallowing or fiberglass skin failing (crushing, cracking, tearing) in any areas.

I have seen older RVs show a lot of stress damage to the landing gear leg fairings and boots. I have deviated from the plans to strengthen the gear leg fairing by applying some strands of glass in the lengthwise direction in the tiny triangular area between the hinge pivot point inside only the lower side and trailing edge. I also did this before I final trimmed the trailing edge. I filled the area only partially so as not to "squeeze" any excess epoxy into the hinge links. As extra protection against that happening, I glued a tiny (maybe 3/32" wide) strip of poster board cardboard as an epoxy dam against the face of the hinge links. I also "floxed" around three sides of the hinge flaps to provide the flaps with a "shoulder" to help stabilize lateral movement of the hinge flaps. I have heard of rivets working loose in the thin fiberglass skin from stress on the part flexing and hope this will help prevent that. If you copy this idea, take care to keep epoxy "OUT OF" the hinge pivot links/holes and to keep the fairing flaps from becoming permanently glued together and to make sure that as the part cures the trailing edge is held in position perfectly straight without pinch/deforming it with clamps. Saran wrap has no thickness and is a great separator and hinge pins punch right through it. I cured the part with hinge pin in place of course. The result is a trailing edge with a little more stiffness and toughness (not too much, I hope) for the rivet line.

I am considering adding gear leg stiffeners as I am building as per plans. I have seen RVs taxiing down grass runways without them with the wheel pants dancing like crazy. It can't be that good on the wheel pants. Stiffeners should help that some. ??? Has anyone considered adding a downsized stiffener maybe fore & aft to the front gear leg as well? Would it possibly help shimmy? Cliff

 

[Mike S]

Van's directions are ok, but a few pics and words might save anyone about to do this some head scratching.

I marked 3 points on the leading edge of the leg fairing and hung a plumb bob from each to mark the distance from the centerline. I also noted the height of each point above the ground. I then marked those 3 points on a board which was clamped to a shop stool. Each point on the board is the same distance from centerline and height above ground as the points I marked on the fairing.

Waterline level, I would assume???

 

[dhall_polo]

foaming at the leg?

I've been offline a few days for xmas and trying to sneak in some plane work.

My primary data points on using foam for the leg fairings are from Checkoways' site, along with a few other builders who've documented the same. It seems now that this is becoming more accepted as a way to fix the problems with the standard documented installation procedure. Hopefully some flying with foam can comment on whether they'd do it again.

Here's checkoway's comments. It looks like he flew with hollow fairings and then opted for the foam after some issues.
checkoway's comments/installation on foam

As you know the instructions just have you clamp the fairing at the top. The upper/lower intersection fairings help prevent fore/aft/rotational movement of the fairing. They aren't attached. They just hug it, but that's all van's requires for standard install. The wooden rod and reinforcement at the tongue are more recommendations, but I think using great stuff foam would be a substitute for both of those recommendations. It helps reduce stress on the clamp, and I would think it would help with shimmy. It certainly provides much better stabilization for fore/aft/rotational tendencies.

As noted, the downside of the foam is that you can't just take the fairing off in a minute and put it right back on. If maintenance is required, I figure I can do anything from cut it open to dissolving the foam out (messy!) to cutting it off and ordering a new fairing.

One thing I can tell you about great foam is be religious with the gloves. This stuff doesn't come off period. I always start off a messy project being good about gloves, but I never learn. Somehow by the end of it, my hands and clothes become victims.

The only thing that bugs me about the use of great foam is that it is flammable, and it's heat rating is below that of dot4 brake fluid. If I didn't know that many others were flying just fine with the foam, this would weigh more heavily on my mind.

I'll post some pics of my wheel pant installation soon.

 

[Vlad]

I did little maintenance (100 hours) on gear leg fairings recently and discovered that powder coating was worn by fiberglass fairings to bare metal. Check them and put protective tape. Guys who are still building please take it into consideration it vibrates and scratches may induce corrosion.