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**nichzimmerman** · 09-30-2016, 09:20 AM

My fuselage started life as a VR kit that was "professionally welded" using TIG. The original owner told me that every dimension was within 1/32". I bought it for a good price but didn't do any measuring before I gave him the money. As I continued with the fuselage assembly I realized many measurements were up to 1/4" off or more. In some places, it's obvious that the assembly was just jigged incorrectly, but others appeared that the tubing lengths were off. This was one of the earliest VR kits. I thought the great advantage of a tubing kit was that its lengths were exact enough to help you jig...? Anyway, my fuselage is nearly complete now and I've stopped worrying about it.

**whee** · 09-30-2016, 10:24 AM

There are several people that have posted about using the tubing kit from Bearhawk Aircraft and it sounds like it is quite nice, price seems right too. I think supporting BH aircraft would be the way to go unless you have a compelling reason to buy the VR3 kit. TIG welding might be good enough reason but I think you'd be fine either way.

My fuselage was built using a VR3 kit and a hefty metal jig. The builder that did it said everything fit perfectly. One of the things I like about the VR3 kit is they beefed up some of the tubes for float flying and they replaced the U-channel above the middle door with a tube. I'm hoping these minor changes will help the fuselage sag so much when loaded up.

**corefile** · 09-30-2016, 12:49 PM

whee what happened to the hefty metal jig?

**patrickh99** · 09-30-2016, 02:13 PM

I had inquired with VR3 about the origins of their tubing and they responded that it was all German. That was over a year ago.

**whee** · 09-30-2016, 03:04 PM

Originally posted by corefile

whee what happened to the hefty metal jig?

I don't know. The builder I bought the project from borrowed it from some one. He told me there were a few jigs made in the early BH days and they get passed around. This particular one is usually somewhere in the mid west I'm told.

**sbmurphey** · 09-30-2016, 07:16 PM

I will put a shameless plug in for Mark G. and Avipro. My greatest disappointment was damage inflicted to the exterior packaging by the shipping company. It looked like they ran into it with a forklift. Mark was great to work with and encourage a very careful inspection and inventory. Thankful there was no damage or loss to the actual kit. No regrets with the Avipro kit. I would certainly purchase it again. Be sure to give yourself a 3-6 month lead time on the order.

Coping is done manually in steel fixtures at the factory. Every kit is fit into the factory jig prior to shipping to insure proper fit.

**jaredyates** · 09-30-2016, 10:07 PM

To get to the specific original question about whether Mark's tubes fit closer than the VR3 tubes, I can't say, because my tubes came with the weld beads included. I have done a little tube fitting before, and I have also been to visit the factory and have seen a fuselage in the jig, and I was impressed with the tight fits that the workers were able to produce. They aren't using a fancy CNC machine, but they are absolutely using craftsmanship and tooling. It is not a low-skill facility.

When weighing the two suppliers that you have named, here's another consideration that Whee hints at: which of the two companies has gladly provided this venue for us to discuss the question? Which is a frequent visitor helping us figure stuff out? Bearhawk Aircraft is a company that has been instrumental in making the Bearhawk as accessible as it is, and thus as popular as it is. Mark is in the business of selling kits, but after builder requests he has made a tubing package available. He has done the same with lots of other parts parts and assemblies, not because doing so makes his job easier. When I think about all he does for us, I'd rather have his tubes even if they were more expensive than VR3. But being that his are actually cheaper, I can't see any reason to go with VR3. The tolerance on both is going to be well within limits for steel work.

**S Lathrop** · 10-01-2016, 06:11 PM

I have a lot of experience doing tube structures. If you time is worth anything, either the VR3 or Avipro tube kits are worth every penny.

VR3 is now making tube kits for my race car designs. And the cost of the kit is way less than the labor and material scraped to do the job by hand as I used to do. I am looking at 1/3 the labor to build a frame from the kit.

As to accuracy, I have not found that when working with the VR3 kit, there were any accuracy issues. I will bet that either kit will be way more accurate when finished than all but the very best hand build fuselages. The VR3 kits are made from solid models of the fuselage taken from Bob's plans. As such the joint fits will be way more accurate than those done by hand and will be way better when it comes to symmetry. And it will be the relative welding gaps at each joint that will be the final determination of overall accuracy. That and good fixtures.

Getting good material is an issue. What I have from the VR3 kits is as good or better than I can get through all my usual sources. Good aero tubing has really become an issue. What is mostly available is junk and questionable compared to what I could get a decade ago. What I used on my Bearhawk, I had from years ago.

**fairchild** · 10-02-2016, 02:10 AM

I am chomping to jump into building a fuselage. Love Tig welding... DONT love hand coping tubing that is 4$ a foot. seems like there would be 136 ways to mess up and 1 way to get
a perfect tight accurate fit. I don't mind doing a little for the tail or gear...... just seems like a job no one could really love. Jigging - fitting - tacking and welding---- now that IS fun. You get
to see an airplane come to life right under your fingertips.

If avi is fitting the tubes into the factory jig ----- then they would HAVE to be pretty good..... Love to see a factory made video on how they cope it....
I was most impressed at the apparent consistent quality of their oxy welds. That's not so common any more. Maybe there are more craftsmen in third world countries than here now.
We seem to be overly infatuated here with high-tech stuff at the expense of skills and craftsmanship. (though i do love my Tig machine)
One day when our power goes out- well wish for their knowledge and skills.

And----- I 100% like the idea of dancing with the one who brung-ya..... (avi-pro)

I have heard 3-rd hand stories of a lot of Chinese made tubing floating around. Knowing how that game would be played----- don't want NONE of that.....

If it is 3 or 4 months lead time---- they must put you in the same cue as the assembled fuselages--- they just don't weld it up. I think VR had 2 or 3 month lead time also.

I will look again to see what avi's tube kits are running currently. Sounds like they would work fine.

we have our house up for sale here in Orlando--- so that may put a hic-cup in my logistics....... ( I have all ready waited too long to start as it is ! )

Thank you all for the opinions- they help a lot ! There is so much to know on something like this ......

One more question----

I am aware there are several books from the WW2 years and some from the 1970's on building steel tubing fuselages......
Did any of you read these--- and did they help---- would you recommend them ? I think one was from the EAA guy who wrote all
the books--- I think he just passed away about 2 years ago....... he had a whole series of books....... cant remember his name.......

Thanks
Tim

**Wayne Massey** · 10-02-2016, 09:38 AM

Any Bearhawk parts Iâ€™ve ever gotten from Mark and the Bearhawk Aircraft Company have been first rate. I would anticipate the same of the tubing kits. Iâ€™m also a firm believer in supporting the Bearhawk community and Mark has been a big part of this community for many years. There would be a hell of a lot fewer flying Bearhawks without his support and service. Considering the VR3 kit is more expensive than Marks tubing kit is a good indication that Mark is truly supporting Bearhawk builders. The cost difference makes it an easy choice. I would also suggest that the motive of VR3 enginering is purely profit whereas Marks primary motive is to provide something that the Bearhawk community was asking for and I believe his position is supportive rather than profit. If I were buying a tubing kit it would be from the Bearhawk Aircraft Company!

**Bdflies** · 10-02-2016, 10:46 AM

Hi Tim,
I think you're referring to the books by Tony Bingelis (sp?). I bought them all, years ago and still refer to them regularly. His books are packed with ideas and techniques, in addition to being entertaining to read. Highly recommended!
if you haven't seen it yet, do a search, in this forum, for 'LSA140 build'. He's documenting the build up, from a tubing kit, from Avipro I believe. The tube fits are impressive, his welding is gorgeous and his innovative solutions to issues are a joy to behold. He posted this video of the coping process: https://www.youtube.com/watch?v=SQZKVPMwPNc

Now my $0.02 about the source of a tubung kit; Avipro is Mark Goldberg. My interaction with Mark leaves me with the impression of a first rate fellow, doing his best to support these aircraft and hopefully make a nickel, or two. Throughout the course of your build, you'll need parts and pieces, that Mark will sell you, at reasonable prices. I agree with Wayne, Jared and all the folks that recommended the Avipro tube kit.

Bill

**jaredyates** · 10-02-2016, 11:16 AM

Everything is relative, but by my standards Mexico isn't third world, and Atlixco certainly isn't. I'd put it a tier above some of the poorer places I've been in Latin America, and those are a tier above Haiti, which I'd agree is third world. I hold the factory workers in high regard not just for their skill but also for their ingenuity, frugality, and the pride that they take in their work. Not to imply that you were meaning to say so, but for others that might be wondering, it would be a mistake to look down on the factory guys as some kind of third-world savages. That's really not what it is like down there.

Originally posted by fairchild View Post

Love to see a factory made video on how they cope it....

Ask, and you shall receive:

Bearhawk Aircraft Kit Factory Steel Construction Techniques

https://www.youtube.com/watch?v=SQZKVPMwPNc

See how the workers make steel parts for the Bearhawk 4-Place, Bearhawk Patrol, and Bearhawk LSA

I have also attached a photo that I took of a tubing joint in the jig prior to tacking, as I was walking by the jig. There is nothing special about this joint, and it wasn't made for the photo. Note that there is a semi-circular gap where the red tube joins the yellow tube, but that is supposed to be there. Zoom in and look at the fit of the unpainted tubes to the yellow tube.

Having a discussion about the quality of the factory work is productive, but regardless of how good it is, I have to wonder if you are putting too much emphasis on the tube joint fit. That alone isn't going to assure you a straight fuselage. There is plenty of tolerance in welding these parts- I recall reading up to 1/16" somewhere. Your filler metal is going to take up any inconsistencies in that range, and the structure is going to be moving around due to all of the expansion and contraction forces anyway. The most reliable and accessible way to get a straight fuselage is to order one that has been welded in the jig. You might get Mark to quote you one of these- the price might be more reasonable than you'd think when you take into account the price of tubing. The tubing kit ships easier, but it is going to take a serious investment in time and tooling to get a tube kit into a fuselage. In case you are afraid of missing out on the opportunity to weld, if you get a bare fuselage with no tabs, you'll still have plenty of welding to do- you'll just not need to be concerned about alignment of critical components.
If national origin is your primary concern for tubing, please ask VR3 how they are able to provide only German origin tubing for the few sizes that nobody else can seem to be able to find being manufactured. Perhaps they are working off of old stock?

**mswain** · 10-02-2016, 11:18 AM

I called Mark to order my tubing kit about a year ago and ended up with a basic welded fuselage! The price on the tubing kit was a no brainier. During the course of conversation he offered to weld it up in the factory jig. It's far from complete but it's the basic structure and all the attach fittings. Now I don't have to fool with building a jig and I know it's straight. The welds look fantastic to me and it's been eyeballed by a dozen builders and everyone is impressed with the weld quality. I scratch-built my wings but am happy to have a head start on the fuselage at what I consider a fair price.

**Steve W** · 10-02-2016, 11:18 AM

No longer supported

http://www.aircraftspruce.ca/catalog/bvpages/constructionoftubular.php?clickkey=3602064

This was the best book I read so far to help on the basics of welding up a fuselage. I'm sure there are better but just haven't read them yet.

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