Shop Layout and Hanging Wings

[Archer39J]

Laying out my shop I overlaid the 4-place envelope scaled from drawing 1B. It seems I can just make it work hanging a single wing at a time. I wanted to ask what issues this might cause I'm not thinking about. Ideally I'd like to complete all of the assembly, drilling and rigging before having to move to a hangar but I don't know if that can be accomplished without being able to hang both wings. Provided I ensure the fuse is perfectly level with the weight of one wing cantilevered off a side, I don't see how that would prevent me from doing anything I would otherwise do with both wings hung. Any advice is appreciated.

[whee]

It certainly could be done but I wouldn't do it. Hanging the wings was one of the most time consuming and stressful parts of my build. I can't think of anything that would have as large of impact on the performance of the plane if not done well.

[Chris In Milwaukee]

It's certainly a lot easier to make sure that your fuselage and wings are square and even if you can get them both on at the same time. But using just math and a tape measure, you can probably get it right. But if you can find the space, definitely having the ability to have both wings on is ideal, in my estimation.

[jaredyates]

More than one builder has waited for a string of good weather and hung the wings on the driveway in front of the garage, or at least drilled the wing attach points and struts there. Then you can move back into the garage and do the rest one wing at a time.

[Archer39J]

Maybe I'm missing something, but if you keep the fuse level and fixed how would that be different than hanging the other wing?

Jared may be on to something there, good suggestion! Though it would be a task to find a level spot in the front of my house...

[jaredyates]

Speaking of myself and not of anyone else, I'd have trouble being that sure that I was able to keep everything level with enough precision during the process of moving the fuselage from one side of the shop to the other. It's like if someone says there's a 1% chance that something will happen, we have to know what the something is. If it is a 1% chance that my milk will expire before the date on the carton, that's one thing. If there is a 1% chance that my wings would be forever crooked, that's another.

[Archer39J]

Laser level and ratchet straps is what I'm envisioning. That would set up a datum you could align the fuse to.

Perhaps a more appropriate question: Does the other wing provide anything other than a counterbalance during the hanging process?

[whee]

If there is a 1% chance that my wings would be forever crooked, that's another.

That's my thinking.

IMO, the balance of the other wing is the least of my worries. I recognize that the process was more involved for me because I was welding the wing mounts at the same time but I think it would be too easy to make a minor mistake that would have major consequences. Your setting incidence, dihydral and sweep and there is very little margin before flight characteristics will be affected. I'm just not confident in my or anyone else's ability to ensure the wings match unless they are done at the same time. But I'm just voicing my opinion and what I'd be comfortable with on my airplane.

My original plan was to hang the wings in my driveway but ultimately decided to trailer the fuselage 30mi to my in-laws shop where the wings were stored which turned out to be the wiser choice. It took us the better part of 2 days to set the wings and tack weld the the mount fittings. I think I'd be comfortable doing it outside on a nice day if I had a factory kit.

[S Lathrop]

If you are going to do one wing at a time, can the laser level. It is not accurate enough. Get a transit level and mount a machinist scale on a stand. The transit level has good enough magnification for you to line up level line with the edge of the scribe marks on the scale. Now you have micrometer accuracy. This is how I leveled my building table and how I level the alignment pads / scales for race cars.

Look at a laser line up against a machinist scale and see how close you can read that line on the scale. Do over the span of the wings.

[Archer39J]

Your setting incidence, dihydral and sweep

Right, in reference to the fuselage. The only comparative measurement between the two wings I can find in Eric's build manual is the wingtip to tail post which, apparently, should be within 1" of each other. Otherwise the leveling measurements are all made on the same wing with reference to the fuselage.

Anyway, it's possible I could get both wings on if I raise the whole plane 2 or 3 feet so the wing will overhang my loft. I may chose this route when the time comes, but it seems to me you can get an equivalent level of precision without needing to do that. BUT, if I don't hang both wings then I can't check rigging and all that at my home shop. Plenty to think about...

[Archer39J]

If you are going to do one wing at a time, can the laser level. It is not accurate enough.

I love me some accurate datum planes, but the build manual is talking about tubes filled with water, is micrometer accuracy necessary?

[whee]

I feel like we are approaching the old ladies in a salon bickering stage so I'll make this last post then just follow along.

I'm not confident in anyones ability to set the fuselage at exactly the same levelness when hanging the second wing. You can only be as accurate as you level and patience allows. I was using a transit level, a digital level, a water level and a 3D self leveling level when I did mine. Getting within 0.1* was very difficult and I wasn't moving the fuselage between wings. Applying Murphy's law, which is very active in my build, you could easily end up with 0.4* difference between the wings in both dihedral and incidence; that's significant to me. Also, in the newsletters Bob says 1" difference in sweep is ok but that was enough I could see it just looking down the wings. I limited it to 1/2" or less.

Good luck whichever route you choose.

[Archer39J]

I feel like we are approaching the old ladies in a salon bickering stage so I'll make this last post then just follow along.

Um, ok. Thanks for your input.

[Bcone1381]

I have written down in my notes that the tolerance for angle of incidence is .2 degrees, or .100" cumulative difference. (a sixteenth is .062) I don't know where I got that figure from, but I suspect its the Bearhawk Assembly Manual. If a method exists to use a micrometer to set the incidence, I would use it. Cessna used a concentric bushing.

[S Lathrop]

I love me some accurate datum planes, but the build manual is talking about tubes filled with water, is micrometer accuracy necessary?

Water in a tube can give a very fine line to measure to. Laser lines are not as fine, at least the 2 I have are not. A little imprecision here, a little there and eventually you have a significant error.