DR-1 (Sands): Builders Group - Page 219

Leatherhead · 5 May 2008, 07:43 AM

Dogtail,

I wish I had taken some pictures when we were attaching the metal fittings to the top/bot of each interplane strut on the Pioneer Flight Museum's Dr.I. I'll try to describe what we did.

It's a two-man operation. I'm not sure what the correct terminology is, but we used what I would call a punch with a concave recess in one end about the same size as the rivet head. One such punch was secured in a vise with the concave end pointing upward. Next place your strut/fitting (with a rivet installed...pointing upward) on top of the punch so that the head of the upwardly pointing rivet rest into the concave recess of the punch. With one guy firmly holding the strut/fitting assembly, the other guy uses the second punch (also with a concave recess about the size of the rivet head you are about to make) and a hammer to slowly smash the protruding rivet end. With pounding, the punch is rotated clockwise (or CCW). With care, a nice rounded, mushroom-shaped head can be produced.

I had never done one before, but with Roger's instruction, I and the guy helping me (I can't remember who it was) pounded out each rivet. I think it took about 2-3 hours to complete all four interplane struts this way. I hope this helps.

Dogtail2 · 5 May 2008, 10:49 AM

Thanks everyone for the replies.

So far I have been experimenting using an aircraft air rivet gun with a concave rivet set correct for 5/32 universal head rivet and flat bucking bar. First I tried putting the manufactured head against the bucking bar and the gun against the protruding rivet shank. This just gave a flattened manufactured head and an ugly lump of a shop head. Then I tried with the shank on the bucking bar and the gun against the manufactured head. This gave a standard flat shop head. I then tried peening this flat shop head with the round end of a ball-pein hammer, and smoothed with abrasive paper to produce a reasonably good looking rounded shop head. But is this method acceptable with regard to strength?

The red lines in the photo point to the 3 peened shop heads, on a scrap strut shoe and trial plywood strut.

Tim Plunkett · 5 May 2008, 04:15 PM

Hay Dogtail2 is that my Dr1 on your computer screen?

Dogtail2 · 5 May 2008, 11:37 PM

Quote:

Originally Posted by Tim Plunkett

Hay Dogtail2 is that my Dr1 on your computer screen?

Hi Tim,

Sure is! Great picture

CORVUS · 9 May 2008, 05:35 AM

Hi,

I've been researching the option of using tube to brace the fuselage rather than the half loops and wires. For me it's a weight issue. I have have talked with builders who have used the tube bracing and they say it adds very little, if any, weight.

Has anyone out there actually weighed a set of piano wire cross bracing, furrells, turnbuckles,and four half round steel fuselage loops and compared the weight to a segement of 5/8" or 3/4" .035 aircraft tube ? Thought I'd ask before buying some and doing it myself.

Thanks,

Lou

Jeff Brooks · 9 May 2008, 06:21 AM

I have weighed them, and the tube is in fact lighter. I will have to go back to look at my building notes to give you the exact numbers, and post it here for you.

To brace one box area, I weighed 6 pieces of tube at the correct length and matched them up with the necessary 12 turnbuckles and the appropriate length of wire. They are close, but the tube wins.

I feel that the wire is still better option though, because when you weld the frame up using tube bracing, you cannot make adjustments to the frame afterwards. If the frame ends up crooked during welding (which can happen when you add heat), you can torque in back into the correct shape using the wire and turnbuckles. You don't have this option with the welded tube bracing.
This adjustment option might also be important after a harder than normal landing too. You can unlace the fabric on the bottom and re-align the frame if necessary.

CORVUS · 9 May 2008, 06:35 AM

Quote:

Originally Posted by Jeff Brooks

I have weighed them, and the tube is in fact lighter. I will have to go back to look at my building notes to give you the exact numbers, and post it here for you.

To brace one box area, I weighed 6 pieces of tube at the correct length and matched them up with the necessary 12 turnbuckles and the appropriate length of wire. They are close, but the tube wins.

I feel that the wire is still better option though, because when you weld the frame up using tube bracing, you cannot make adjustments to the frame afterwards. If the frame ends up crooked during welding (which can happen when you add heat), you can torque in back into the correct shape using the wire and turnbuckles. You don't have this option with the welded tube bracing.
This adjustment option might also be important after a harder than normal landing too. You can unlace the fabric on the bottom and re-align the frame if necessary.

Hi Jeff,

Thanks very much for writing. Very interesting in all respects !! If your weight data is handy it would be nice to see but don't spend too much time looking for it. Your post has given me plenty of food for thought.

Regarding the possible twist in the finished fuselage if using tube bracing. Would it be possible to post heat those welds and straighten out any warps ? Apparently it's being done by other builders so there must be a way to make everything straight. Another point is there are so many newer type models being built that use a steel tube frame and no wire bracing. Wire bracing being a thing of the past.

Again. many thanks for writing

Lou

Lyle · 9 May 2008, 06:52 AM

Quote:

Originally Posted by CORVUS

Another point is there are so many newer type models being built that use a steel tube frame and no wire bracing. Wire bracing being a thing of the past.

Hey Lou,
I know what you mean about the wire bracing, it's not what you find on a lot of the more modern homebuilts but it still is an effective method of bracing. Something like spoked wheels, looks great on a Nieuport or Fokker but not a Lancair.
I think Jeff has it right about being able to true things up again with the wire and turnbuckles after a jostled landing or taxiing on a rough field. Also an eye opener about the weight of either method...one always thought wires and turnbuckles would be lighter!
I suppose in the end it's how totally authentic you want to be. I don't think we can be 100% in that being that it's 2008 and not 1918, but it's possible to nudge it pretty close. Witness the Memorial Flight Dr.I or Richard Enos' Fokker D.VII--these are fantastic planes.

Jeff Brooks · 9 May 2008, 06:57 AM

I think that if you spent a lot of effort in the jigging of the frame when doing the final welding, you could get the frame straight easily enough. But, if that frame gets out of alignment later, correcting it becomes quite a chore.

You need to weigh this option with other options like breaks, steerable tailwheel and any other mods to make this decision. Otherwise you might have less controll on landings in crosswinds, and you develop a need to make regular adjustments to the frame.

Jeff Brooks · 9 May 2008, 06:59 AM

Quote:

Originally Posted by Lyle

Also an eye opener about the weight of either method...one always thought wires and turnbuckles would be lighter!

I agree with the eye opener ... think BRASS turnbuckles, and it makes sense though.