Brainstorming request; repairing a well-rusted cluster.

[mhorowit]

I could use some ideas on how to approach repairing the well-rusted cluster shown at http://members.cox.net/mhorowit/cluster/
Thanks, MikeH

[Guest]

Re: Brainstorming request; repairing a well-rusted cluster.

splice in a new section of longeron and then do an outside sleeve splice on each cluster tube

finger patch is not appropriate

[VictorBravo]

Re: Brainstorming request; repairing a well-rusted cluster.

Yep, that's pretty far past a simple finger patch! It looks like you have to possibly even make up a new cluster on the bench and splice it in to the airplane. Get rid of all that pitting and cratering while you're at it. The external sleeves along with several rosette welds seems to be the direction to go.

[N96337]

Re: Brainstorming request; repairing a well-rusted cluster.

Personally, I'd cut the whole thing out, replace the bottom longeron, and replace tubes to the next cluster, or at the very least use inner-sleeve splices. Outside sleeves look terrible in my opinion.
JH

[Guest]

Re: Brainstorming request; repairing a well-rusted cluster.

Personally, I'd cut the whole thing out, replace the bottom longeron, and replace tubes to the next cluster, or at the very least use inner-sleeve splices. Outside sleeves look terrible in my opinion.
JH

agree about uglies- but I find the diff in labor is 50% and in places where they are out of sight it gives my customers a cost break so I use them.

In Mike's cluster I think all the cluster tubes are behind the fabric line

[Guest]

Re: Brainstorming request; repairing a well-rusted cluster.

I like them for Aeronca case frame repair on rear tubes.

Allows easy adjustment of the final rear tube length to achieve squareness between the hinge line and front tube axis. Weld rear tube to main tube first the use the telescoping property of the splice to make adjustment.

[Ragwing nut]

Re: Brainstorming request; repairing a well-rusted cluster.

Cut the entire thing out and start over. Depending on what tubes are attached, i have a tendency to replace the entire cross tube to eliminate as many spliced tubes as possible.

Mike

[mhorowit]

Re: Brainstorming request; repairing a well-rusted cluster.

splice in a new section of longeron and then do an outside sleeve splice on each cluster tube

Need a bit of clarification. I can visualize cutting the longeron away from the rest of the cluster and replacing it with an equal size tube. Now I'm left with a great glob of old cluster. Were you suggesting cutting each tube back to good metal and redoing the cluster? What's going to spring apart? - MikeH

[VictorBravo]

Re: Brainstorming request; repairing a well-rusted cluster.

Need a bit of clarification. I can visualize cutting the longeron away from the rest of the cluster and replacing it with an equal size tube. Now I'm left with a great glob of old cluster. Were you suggesting cutting each tube back to good metal and redoing the cluster? What's going to spring apart? - MikeH

Before you cut anything apart, make up a jig for it. Take some steel sheet, maybe .090 or so, and some small pieces of steel angle. The sheet should extend several inches or more past the bad cluster in all directions if possible.

Clamp or even tack weld the sheet onto the back side of the cluster, and weld the angles onto the jig sheet, held tightly against all the various tubes on either side of each tube.

Then mark where this jig fits exactly on the GOOD sections of the longerons and uprights, so you can put it back in the same place.

Then remove the jig and cut out the bad cluster.

Then tack weld or clamp the jig back in place and you have a re-assembly jig so all the new tubes go back in at the right place.

IMHO, most of the external sleeve repairs indeed will be behind the fabric (due to the side and bottom wood stringers).

You would see a little lump in the fabric at the outer corner of the longeron where this external tube overlap is. IMHO, that becomes part of the character of the airplane. (I for one have a couple of lumps I didn't have when I was a kid... character is one of the T-craft's strong suits!)

However, you can easily minimize this if it bothers you.

1. CAREFULLY file off the globs of weld parallel to the outer tube. Do NOT remove anything in the "fillet" between the inner (old) and outer (new) tubes, just take off anything that is fully above the outer tube.

2. Blast and then epoxy prime the repair area thoroughly, using a small stiff brush with a JABBING motion to physically FORCE the epoxy into the nooks and crannies of the weld.

(This brush-prime jabbing should be done at ALL of the clusters, regardless of whether you spray prime or brush prime the entire fuselage. When using epoxy, seriously consider brushing the entire fuselage for your own safety as well as getting better protection on the tubes... the 1940 Piper factory tour film I saw shows the primer being delicately and daintily applied to Cub fuselages... with a GARDEN HOSE!)

3. After the primer is cured, apply some body filler (Bondo etc.) over the joint and sand it smooth so you cannot see the transition between the new and old tubes.

4. Re-apply epoxy primer anywhere the sandpaper scratched the previous layer of primer.

[high time cub]

Re: Brainstorming request; repairing a well-rusted cluster.

Enjoy!

"4130 Tubing Repair"

http://www.supercubproject.com/theater/default_noie.aspx

Jim

[tawadc95]

Re: Brainstorming request; repairing a well-rusted cluster.

if this plane is for display purposes only use some bondo
If you plan on actually flying it why not buy another one
Is this what the gear parts are from
I doubt I could ever trust this one out of ground effect
Sorry to be harsh but aviation is more about safety than sparing cost in my opinion.

[tawadc95]

Re: Brainstorming request; repairing a well-rusted cluster.

cool video cub man!
makes me want to try it out

[VictorBravo]

Re: Brainstorming request; repairing a well-rusted cluster.

if this plane is for display purposes only use some bondo
If you plan on actually flying it why not buy another one
Is this what the gear parts are from
I doubt I could ever trust this one out of ground effect
Sorry to be harsh but aviation is more about safety than sparing cost in my opinion.

I'm really sorry to be rude, but... Nonsense. Aviation has always been about cost as much as anything else. There is only one small quadrant of aviation where money is not the primary object. The B-2, the F-22, the SR-71, and whatever replaced it. The OTHER 90% of aviation is ALL about cost. Even the Space Shuttle was at least halfway about cost.

Ask any old retired airline pilot why they went to a two man crew instead of three. Ask Boeing why they went from four engines to two. Ask the founders and trailblazers and fathers of the experimental aircraft movement what drove most of the big innovations and designs in light aviation in the last 50 years. Ask ANY pilot in Europe or any other part of the world what is the one thing that everything in their daily world of aviation hinges upon. Ask Cessna or Piper or even gold *(#*% plated Beechcraft what the biggest single factor is in how they build airplanes if they want to actually sell one.

I have advertisements for Taylorcrafts in the 1930's and 1940's. Every one of them says "The leader in the low-price field".

Safety is of course a big concern, as it should be. But if the cost of flying is not kept under control then there will be no aviation... and all the FAA people will be out of a job, and one of the things that makes America the greatest country in the world will be lost. The FAA engineer / inspector at his meeting with Mark and Terry even acknowledged that it is a very important factor.

My comment about using Bondo was to make a non-structural smooth fairing over an FAA approved 100% safe and time proven tubing splice.

Sorry for sounding like an attack dog, but Mike is doing something really really important, both in the grand scheme of things and for his personal achievement as well. He is not giving up on a damaged airplane any more than a good doctor gives up on a patient. Go get 'em Mike!

[mhorowit]

Re: Brainstorming request; repairing a well-rusted cluster.

Enjoy!

"4130 Tubing Repair"

http://www.supercubproject.com/theater/default_noie.aspx

Jim

Neat! - MikeH

[mhorowit]

Re: Brainstorming request; repairing a well-rusted cluster.

if this plane is for display purposes only use some bondo
If you plan on actually flying it why not buy another one
Is this what the gear parts are from
I doubt I could ever trust this one out of ground effect
Sorry to be harsh but aviation is more about safety than sparing cost in my opinion.

I think VB's use of the word 'bondo' may have thrown you, but a careful read would have shown the bondo was applied only as a smoothing agent.
Perhaps your approach is purely economical, in which case you could be correct, but economics have little to do with this project.(actually they do - I'm wrestling with the need to open up the epoxy chemicals to do a little work and am concerned the catalyst and primer will go bad before I can use it up) It's an opportunity to learn; unfortunately, at the moment it's like drinking out of a firehose. Also, I would not expect anyone to fly this aircraft without being fully aware of its structural integrity; I have a pro who will poke and prod before giving me permission to cover.- MikeH