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-   -   Fuselage repair advice (http://www.Wattflyer.com/forums/showthread.php?t=68933)

Beemerider 12-06-2012 09:49 PM

Fuselage repair advice
 
4 Attachment(s)
I'm working on a repair and recovering of my Explorer 2M sailplane. This was an ARF of 12+ years ago that I bought but never flew until this past spring. This is the plane that I learned on (and it shows). Installed a brushless motor and have had many nice flights. This has been on the shelf for the last few months waiting on weather appropriate for repair.

I'm in process of stripping all the old covering and repairing damage when it fell from the top of a tree. (I have no idea how it got up there) I've some experience on repairing damage (gained quite a bit of experience in that this year) and I have my own ideas on this but would like to hear from some folks with far more experience than I. The tail feathers were pretty heavily damaged and I've pretty much finished that part. The entire tail section broke free from the fuse with the control rods still holding on. I'm ready to join the wayward tail but I need some direction as how to join it and keep it strong. As you can see from the pics it's a jagged break and actually it will pretty much join up with almost all the gaps filled. But I feel like it will be prone to break again unless I manage some sort of internal reinforcement. Do I cut more balsa away so I can splice in some very thin plywood?

Also you can see the stock control rods--wood dowels with clevis attached. I intend to reuse them unless there is a better alternative. I know low weight is the goal in a sailplane but that's not my primary.

CHELLIE 12-06-2012 10:06 PM

if the tail section will join up, use 30 min epoxy to reattach it with, it will be stronger than what you had before, fill in any gaps with a little epoxy mixed with micro Balloon, use 6mm CF tube in place of the wood dowels, its much much lighter, there your all set to go :D

Beemerider 12-06-2012 11:02 PM

Quote:

Originally Posted by CHELLIE (Post 891217)
if the tail section will join up, use 30 min epoxy to reattach it with, it will be stronger than what you had before, fill in any gaps with a little epoxy mixed with micro Balloon, use 6mm CF tube in place of the wood dowels, its much much lighter, there your all set to go :D


Thanks Chellie!

So I can epoxy it back better than new! So next time it falls out of the tree the tail won't break off. Cool!!:Q

Can I fix wings like that too?:silly:

CHELLIE 12-07-2012 12:52 AM

Quote:

Originally Posted by Beemerider (Post 891229)
Thanks Chellie!

So I can epoxy it back better than new! So next time it falls out of the tree the tail won't break off. Cool!!:Q

Can I fix wings like that too?:silly:

Sure You can fix the wing that way too :D I will Let You :ws: Stay away from those Darn Trees ;) they like to Reach out and Grap rc Planes out of the air :rolleyes: As me how i know :red: :Q LOL

kyleservicetech 12-07-2012 02:23 AM

Quote:

Originally Posted by Beemerider (Post 891203)
I'm working on a repair and recovering of my Explorer 2M sailplane. This was an ARF of 12+ years ago that I bought but never flew until this past spring. This is the plane that I learned on (and it shows). Installed a brushless motor and have had many nice flights. This has been on the shelf for the last few months waiting on weather appropriate for repair.

I'm in process of stripping all the old covering and repairing damage when it fell from the top of a tree. (I have no idea how it got up there) I've some experience on repairing damage (gained quite a bit of experience in that this year) and I have my own ideas on this but would like to hear from some folks with far more experience than I. The tail feathers were pretty heavily damaged and I've pretty much finished that part. The entire tail section broke free from the fuse with the control rods still holding on. I'm ready to join the wayward tail but I need some direction as how to join it and keep it strong. As you can see from the pics it's a jagged break and actually it will pretty much join up with almost all the gaps filled. But I feel like it will be prone to break again unless I manage some sort of internal reinforcement. Do I cut more balsa away so I can splice in some very thin plywood?

Also you can see the stock control rods--wood dowels with clevis attached. I intend to reuse them unless there is a better alternative. I know low weight is the goal in a sailplane but that's not my primary.

Yeah, I've repaired the tail ends of a fuse busted like that over the past 40 years. One way for me that was very effective, was to buy a sheet of 1/32 regular plywood, NOT lite ply!

Cut pieces of that ply to fit inside the fuse such that the tail section will fit over those pieces of ply. Do this for the left and right sides. The pieces should extend perhaps 1 1/2 inches on each side of the break. A sharp pair of sissors works very well for this purpose. (If that sissors is going to be used on fabric later on, don't get caught!)

Then with slow drying epoxy, epoxy those pieces inside the fuse and clamp til set. With more epoxy, slide the tail over the pieces of ply, and line up the balsa portions, front and back. This is critical, make certain that tail is on straight!!!!

Last but not least, when all is cured, make several more pieces of that 1/32 ply to fit on the outside of the fuse, making a sandwich of plywood inside and outside with the original balsa in between. Sand a slight taper on the pieces of 1/32 ply so the joint won't be as obvious.

If you are careful with the amount of epoxy used, this will be very light, and very likely stronger than it was originally.

Beemerider 12-07-2012 03:48 AM

Your approach is pretty much what I had in mind although I wouldn't have thought to use the 1/32 ply. This is not the first time I've had to repair the tail. Learning to fly is hard on your first plane.:concern:

Many thanks to you both!

kyleservicetech 12-07-2012 04:55 AM

Quote:

Originally Posted by Beemerider (Post 891260)
Your approach is pretty much what I had in mind although I wouldn't have thought to use the 1/32 ply. This is not the first time I've had to repair the tail. Learning to fly is hard on your first plane.:concern:

Many thanks to you both!

Your welcome!

Let us know how it works out.

solentlife 12-07-2012 03:22 PM

If the balsa marries well .... and you sort out any spilts along grain etc. - then I would use common 5 min Epoxy to join it back together ....

Any splits you find - there are ALWAYS splits in balsa when it breaks ! Carefully run CA along them - BUT only small amount - don't start soaking gobs of CA into the wood as that creates a hard point that shatters at joint to non-CA wood.

You can use inserts of balsa strip to bridge the joint ... one each side. That way you are not adding weight at tail which is usually a taboo item !!

Sorry to the suggestion of ply inserts - but that even just a few grams is adding weight. If you must add extra - use FOAM ... yes FOAM ...

For the pushrods ... CF arrow shafts ... garden flower stakes ... bamboo ..... there are loads of alternatives. I picked up a bunch of 10 flower stakes in pine 6mm rod ... $0.10 the bunch ... 30cm long. Make beautiful push rods .....

Nigel

kyleservicetech 12-07-2012 06:04 PM

Quote:

Originally Posted by solentlife (Post 891282)
You can use inserts of balsa strip to bridge the joint ... one each side. That way you are not adding weight at tail which is usually a taboo item !!

Sorry to the suggestion of ply inserts - but that even just a few grams is adding weight. If you must add extra - use FOAM ... yes FOAM ...

Nigel

1/8 inch thick balsa strip, or 1/32 inch thick ply inside and outside might weigh the same ????

Foam? This looks to be a fairly good sized model, and that tail structure has to be very strong to prevent coming apart in the air. (I've built a number of sailplanes over the years with very small fuse cross sections at the tail location)

cyclops2 12-08-2012 03:50 PM

I like strips of cloth covered with epoxy. Tough as heck. Then a paint job.

kyleservicetech 12-08-2012 04:52 PM

Quote:

Originally Posted by cyclops2 (Post 891397)
I like strips of cloth covered with epoxy. Tough as heck. Then a paint job.

Would that be fiberglass cloth?

cyclops2 12-08-2012 08:10 PM

Any fine, tight weaved cloth, Dacron, or anything else at a Fabric Shop. Big choice of materials to pull on, before buying. I cover all boats & planes with their cloths. Colors & patterns. :):)

kyleservicetech 12-08-2012 08:21 PM

Quote:

Originally Posted by cyclops2 (Post 891413)
Any fine, tight weaved cloth, Dacron, or anything else at a Fabric Shop. Big choice of materials to pull on, before buying. I cover all boats & planes with their cloths. Colors & patterns. :):)

I have to say this :D :D Hope you are not using a pretty pink flower print for your covering!!!

solentlife 12-08-2012 08:43 PM

Quote:

Originally Posted by kyleservicetech (Post 891308)
1/8 inch thick balsa strip, or 1/32 inch thick ply inside and outside might weigh the same ????

The balsa would be inset INTO the fuselage sides ... not added extra inside or out. Cut-outs would be made across the joint to let these in giving strength across the join for no additional weight.

Quote:

Foam? This looks to be a fairly good sized model, and that tail structure has to be very strong to prevent coming apart in the air. (I've built a number of sailplanes over the years with very small fuse cross sections at the tail location)
Foam can be used to fill INSIDE the fuselage across the joint and is surprisingly strong - as long as it does not compromise any control rods etc.... I flew slope and thermal gliders in UK for years ... so I understand about the very narrow tail ends ! This is why such solutions as foam and inset strips were used ...

Nigel


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