Gluing aluminum

Rivets, Ed! AD-470 type driven rivets.

While 6061-T6 can be welded, such would never do a fuselage truss. That sweet curve would turn into a series ov straight chords.

Ug...

Yeah, that's why I wondered. I couldn't picture welds that wouldn't make a mess.

But the frame members appear to meet at points, as in a tubular space frame. How do you get rivets in there? How many rivets pin a typical joint?

-- Ed Huntress

Extruded angle - mated on the flat faces.

The vertical members attach to the outside (vertical) longeron flange, the horizontal members attach to the horizontal flange.

Everything attaches on the inside face of the longeron - well, except the landing gear cross bars / lift strut attach points (a pair of 1-1/4" extruded angle pieces) that are bolted underneath the longs.

Edge margin is a little iffy with 3/4" flanges, but the 1/8" thickness (each) is more than adequate metal to hold a rivet. It's not like riveted thin sheet metal. More like Lugs.

Some use two 1/8" rivets per joint - some use a single 5/32 or 3/16. I've done them both ways.

It produces a very rigid, fairly light weight structure that is very robust.

For example, a Graham Lee Nieuport fuselage the weight increase is about 6 to 8 pounds.

A very slight factor compared to the structural integrety, low cost and ease of construction afforded by extruded angle construction.

Richard

That's interesting, and surprising. So, many of those members are held together with a single rivet.

I'd like to see that one in a finite-element analysis program.

-- Ed Huntress

The control surfaces on a DC-3 were constructed of an aluminum frame covered with fabric. A not uncommon method of construction for their time.

To the best of my knowledge there were no "spare" wings or fuselages for the DC-3. Like any other aircraft if there was damage it was repaired.

In Viet Nam when we mounted the Mini Guns in the DC-3 (C-47) we found that many of the fuselage formers that supported the floors were corroded to the extent that it was thought that they would not support the recoil of the guns. The formers were simply removed and new ones fabricated in the field and riveted into place.

Bruce in Bangkok (brucepaigeATgmailDOTcom)

That's my kind of airplane. d8-)

-- Ed Huntress

In Gann's book "Flying Circus", he mentioned a DC-2 1/2, A DC-3 with a DC-2 wing on one side.

Ever work on a Pembroke (sp)? I was working on one when I hit the little lever on the yoke. It sounded like a tractor trailer was standing next to the aircraft. The lever was for the air brakes. That plane had air brakes to stop the ground roll.

John

Is this serious? Was it intended for flying in circles?

-- Ed Huntress

Agreed - it would be interesting! Let me see it when you are done. ok?

Richard

I suppose that anything is possible but I have seen DC-2's and they were substantially different from DC-3's. The most noticeable was that they were covered with much smaller sections of aluminum and (IIRC) used brazer head rivets instead of flush rivets...... but it was a long time ago.

Bruce in Bangkok (brucepaigeATgmailDOTcom)

I believe this is the story you are refering to...

Yankee Ships in China Seas: Adventures of Pioneer Americans in the Troubled ...

"But by the time he got there, things had happened. Fearful that more Jap bombers would return to finish of! the damaged before if could be repaired. Woods and his crew and his coolie helpers had dragged the DC3 off the field and three miles down the road to hide it in a clump of bamboo trees. Within an hour after they had completed their camouflage job, a flight of seven Jap bombers returned and spent nearly an hour looking for the wounded Douglas before giving up and winging away. On the second and third days flights totaling up to 50 bombers scoured the countryside around Siufu, some of them diving to within 200 feet of the boys and the ship huddled under the bam-boo without finding a trace of the Douglas. 'That third night the two skippers, Woods and Sweet, and their crews fitted the DC2 wing to the DC3 and put the ship in technical order. Meanwhile the coolies filled in the bomb craters to make a runway. Working desperately against time, just as the first gray light of day came threading through the trees, Woods took the 1 >?j or! with its unbalanced monoplane and Sweet fol-lowed him with the DC3. Four hours later both landed safely in Hong Kong.

By Daniel M. Henderson

Aack! With the simple FEA program that I use, it would take me a week just to enter the data, if the program would handle it at all. (What's the modulus and radius of gyration for those sections? Tear-out strength versus shear strength for the location of rivet holes? My God...)

That's where the fancy and expensive CAD programs with integrated FEA modules are worth their salt. I don't have one.

But I'll make some guesses: The structure probably is very rigid; that's a function of geometry and elastic modulus rather than strength. As for strength, the individual elements probably do OK in tension, if the rivets are sized right and their locations provide enough tear-out strength. My question is how they do in compression. Non-tubular sections usually don't do well in resisting buckling. I suspect that is the primary failure mode for most loadings.

However, it's probably scaled well enough that it's plenty strong in practice.

-- Ed Huntress

That's the way it is. Think of the rivet more to serve as a fixture while the glue is curing and giving security for peel-off.

Nick

Yep. On all counts.

It's basically South Texas Farm Technology. Nothing fancy - but it works out very well.

As an aside, the Boeing F4B2 series were built this way too. Not a whole lot of new stuff under this old sun...

As for compression of non-tubular sections, you are absolutely right again.

One fellow proposed turning the longerons inside out.

Makes sense from one point of view.

With the open angle to the outside the fabric has a natural chamfer the length of the longerons. Makes for a nicely faired edge.

The internal structure is then mated up 3/4" inside the skin - lot less chance of touching it when sanding the finish (ooppss!!) and cutting a hole in the fabric. (howcom this darned spot keeps getting bigger?)

But with the angle open side facing outside the compression strength is seriously reduced. The flanges open a lot easier than they close...

Other than a few guys using aluminum tube tail wheel legs, there has never been a structural issue.

Richard

On Mon, 1 Oct 2007 21:16:18 -0400, with neither quill nor qualm, "Ed Huntress" quickly quoth:

Perfect for the Reno races, wot? With the shorter wing, it would miss the pylons easier, too. ;)

There's only a ten foot difference in wingspans but a 47 s/f area, so I'm wondering how much of that is in fuselage width.

-- They also serve who stand and weld.

--David Weber, On Basilisk Station.

Field expedient to get a damaged aircraft to a better location for repairs.

Only wing available was DC2 parts.

I recall reading that a very large wrench was grafted onto the control yoke, to offset some of the requirement to keep the smaller wing level.

A product of a very different time!

The mechanics, and the airplane both!

Cheers Trevor Jones

Richard, what in your opinion is the best engine for a small parasol monoplane like this?

-- Ed Huntress

Light miniature aircraft(LMA) in florida used rivet bonded alum square tube in the homebuilt aircraft. Dick Schreder used bonded alum with foam ribs in several of his kitted sailplanes. Bede used bonded wing modules (glass) that slid over a tubular alum spar. Pat