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Rv-3 gear legs and fairing questions

hookdriver

hookdriver

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Well, finally did it. Ended up with an RV-3b project. Almost bought a -4 then an -8 now I have a -3. The wings and empennage are done. The fuselage is in the very early stage. Undoubtedly there are missing parts.

One thing I know for sure I need to fix is the mount/gear legs. Someone along the way took the gear legs and mount from my kit and threw their messed up legs in. My question is do the new mount/ gear legs for the -3 come match drilled?

Next question is: do any of the -4 intersection and empennage fairings work on the -3?

There are a million more questions inbound. Just happy to be part of the crowd and I look forward to talking RV with you folks.
 
For the first question, no, they don't come pre-driied or pre-aligned. You get to do that yourself.

On mine, there was very little free space for that bolt and nut to go, so be sure of your measurements.

Dave
 
David Paule said:
For the first question, no, they don't come pre-driied or pre-aligned. You get to do that yourself.

On mine, there was very little free space for that bolt and nut to go, so be sure of your measurements.

Dave
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hookdriver said:
Well, finally did it. Ended up with an RV-3b project. Almost bought a -4 then an -8 now I have a -3. The wings and empennage are done. The fuselage is in the very early stage. Undoubtedly there are missing parts.

One thing I know for sure I need to fix is the mount/gear legs. Someone along the way took the gear legs and mount from my kit and threw their messed up legs in. My question is do the new mount/ gear legs for the -3 come match drilled?

Next question is: do any of the -4 intersection and empennage fairings work on the -3?

There are a million more questions inbound. Just happy to be part of the crowd and I look forward to talking RV with you folks.
Click to expand...
You might want to contact The Mother Ship and ask. The gear on SuzieQ came predrilled but I can't remember if I had to had that done with a special order or not. Call them.
 
So the first thing you realize about the -3 is that not only don’t things like the gear legs come pre-drilled, you’re going to have to forge your own drill bit first! Kidding….kidding….but only a little!

Second thing - you are unlikely to get many answers out of the Mother Ship. If it’s a true structural question, yes - absolutely, you need engineering support. If it’s a “how do I build this?” Question…well even a dozen years ago when we built ours there was no one there (except Van) who had built one. So those of us on the forum who have started with an RV-3 kit and have flying airplanes are more likely to at least give you ideas.

The truth is, once you’ve built one short-wing RV from the “good old days” (-3, -4, -6) you pretty much know how to build it - or have something to reference.

Upper gear leg fairings are going to be unique to the -3. Lowers will probably work from another model if you are using the modern pressure recovery wheel pants.

A good luck!
 
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Yeah. I knew I was getting in the deep end of the pool on this project.

Looks like the previous owner mis drilled the mount/had a gear leg that shimmied. The bolt hole is too close to the weldment and the hole is elongated. My plan is to weld it shut and match drill a set of new gear legs to it. Langair has a process to match drill the mount to some old gear legs….i think. Not sure. I thought about putting an ad on the classifieds for a new mount and gear. As of now I am gonna try and rehab my old ones.

Might be a mistake trying to save this fuselage. Time will tell. Thank you all for the help and support.
 
I really hope you are able to successfully finish your 3, It is an absolute pleasure to fly
 
When you get a little further along, you'll be able to repeat this phrase in exactly the right tone of voice:

"Well, it's an RV-3." It'll become a sort of universal answer to so many questions of comments from other RV builders. Basically, everything Paul said is correct.
 
hookdriver said:
Yeah. I knew I was getting in the deep end of the pool on this project.

Looks like the previous owner mis drilled the mount/had a gear leg that shimmied. The bolt hole is too close to the weldment and the hole is elongated. My plan is to weld it shut and match drill a set of new gear legs to it. Langair has a process to match drill the mount to some old gear legs….i think. Not sure. I thought about putting an ad on the classifieds for a new mount and gear. As of now I am gonna try and rehab my old ones.

Might be a mistake trying to save this fuselage. Time will tell. Thank you all for the help and support.
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Just chatted with a friend who drilled the gear legs on both his -6 and -3. The -3 was so spot-on he has just put on only his third set of tires in 680 hours!
 
hookdriver said:
Yeah. I knew I was getting in the deep end of the pool on this project.

Looks like the previous owner mis drilled the mount/had a gear leg that shimmied. The bolt hole is too close to the weldment and the hole is elongated. My plan is to weld it shut and match drill a set of new gear legs to it. Langair has a process to match drill the mount to some old gear legs….i think. Not sure. I thought about putting an ad on the classifieds for a new mount and gear. As of now I am gonna try and rehab my old ones.

Might be a mistake trying to save this fuselage. Time will tell. Thank you all for the help and support.
Click to expand...
I have just done some work on an RV-4 with a damaged mount. What I would recommend is to fabricate a new set of gear leg tubes. They are standard 4130 sizes and are rose welded into place where the bearing surfaces on the legs rest. You also have to ream the tube after welding. I think the RV-6 plans have a good drawing of them. Then drill the holes to match you gear legs off the aircraft. This makes it much easier to find the hole and drill on a drill press. Next step is to create a jig for the engine mount and mount the old mount to it and cut-away the old gear legs. Being careful not to shorten the interconnecting tubes. That is only cut-away the old gear mount tubes. You can then slide your repaired mount tubes into place and set the angles exactly. Tack weld back into place, and re-weld the new mount tubes in place.
on the repair I did took about 60hrs of work.
 
Sounds like that may end up being what I have to do. Just cut the tubes free and weld new ones in.

Right now I am getting the project moved to my hangar and figuring out what is missing/ damaged. All of my bulkheads from 305 aft are hosed. Ordered them…hopefully they show up soon.

My kit has no cowling, canopy or fairings. When I called vans before I bought the project they said they still support the kit….but werent sure about a delivery tine line on parts.

You guys think I should get a cowl and canopy kit on order now know ing that it might take a while to get?
 
The original F1 rocket was based on an RV-3. They had a really nice fastback tip over canopy. Might be worth talking to them. They have new turtle deck ribs. One day I might convert my side-tipper to it. Order the parts as soon as you can. My kit took over 3 years to be delivered completely.....
 
sportflyer said:
The original F1 rocket was based on an RV-3. They had a really nice fastback tip over canopy. Might be worth talking to them. They have new turtle deck ribs. One day I might convert my side-tipper to it. Order the parts as soon as you can. My kit took over 3 years to be delivered completely.....
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Correction, the Harmon Rocket 1 was based on an RV-3. The Harmon Rocket 2 was based on the RV-4, and the F1 is a clean-sheet design (inspired by the HR 2).
 
Been doing some reading and it looks like some folks are having mount cracking issues on the -3 and -4. Since it looks like I may have to replace the gear leg tubes in my mount would it be a good idea to weld in some gussets down there?

My thoughts are..... well it can't hurt....and.....it may just cause cracking somewhere else.

What do you folks think about it?
 
I believe, without hard evidence, that the occurrence of cracking in -3/-4 mounts is not common. There is a current thread with major cracking 😲 on a -4 mount and gussets welded in. A chat with The Mother Ship might shine some light on what you have in mind. I agree with your thinking that stress might be projected to other parts of the mount. Opinion: the original design seems to have worked well for decades and many thousands of hours of service. IMHO...
 
I added some gussets. The red arrow identifies what I added. The rest were stock, I think. These were at the bottom-most joints. I used .090 4130 only because that was all I had at the time; .063 would have been a better choice. I did this after another RV-3 owner sent me photos of her cracked engine/landing gear mount -- so cracking has occurred on a -3B at least once before.

Gusset 1A.jpg

I found the photo of the cracked mount. The blue arrow points to it. You can see the relative geometry although the photos were taken from different directions.

Crack SA.jpg

Dave
 
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So…. Not super common, but, it has happened. I just figured if I was replacing the down tubes anyway I might as well add a gusset or two. Just started to wonder if it would crack the fuselage mounts or fire wall. Cracks on the inner mount would be harder to inspect for.

All of this is the result of getting up to take a leak at 2 am and letting my mind get the best of me.

Thanks for the patience

Josh
 
Gussets without post weld heat treat to relieve any weld induced stress might be counter productive. 4130 draws with heat almost as bad as stainless. And cracking around welds is very common in the race car/ sand rail world.

If your going to add gussets you really should have some post weld heat treat done. Any industrial fab shop should be able to do this for you, and it's not very expensive.
 
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