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d80 repair

Started by wdeighton, April 24, 2012, 21:14:57 pm

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wdeighton

Well the wind has been bad, and I have been in the loft mending, and trying to take some pictures along the way so I thought I would share a bit here.
Last year in one fowl swoop Hurricane Catrina took me to HH, where I killed my D60 and badly wounded my D80.
It has taken nearly a year but the D80 is nearly ready to fly. the wing needs some paint and wiper work but if the wind comes she will be there as she is.

The Damage
Well the Fuz broke in 2 at the back of the wing seat opening (Access for ballast  and radio tray). The fin and stab ripped out along with its inserts that hold it into the fuz.
The wing. O dear, where to begin. The RHS Tip ballast exited through the side if the wing (see picture with stirrers holding the skins open). There was some de-lamination of the wing skins around the servo bays, One aileron was badly damaged, and some leading edge damage. may be more but that is what I can recall.

[smg id=27086]

[smg id=27087]

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wdeighton

Fuz Repair

This to me was always going to be the hardest, and I think it was.
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The first thing I tried was to tape it together and use cyno and glass cloth to hold it so I could to the internal repair. Because of the weight and my heavy hand it didn't work. I couldn't get it lined up well, and it kept breaking free.
Left it for a couple of weeks.
Got home from work one day, went into the shed, pulled out some skirting boards, into the loft (Mrs thought I was going crazy) cut it up, glued and screwed and made a jig.
[smg id=27071]
There was a process then of adding car body putty and pressing a good fuz with wing and stab in place onto the fixture. (Not how Tony does it but I don't do measuring very well.)
[smg id=27072]

The D80 has 2 layers of Kevlar, so round the joint I tried to remove one, and I prepared the edges to make sure I could hold the fuz in the correct position. Then into the Jig
I then started my repair on the inside with a layer of 25mm wide kevlar  along the break, followed by a 50mm wide kevlar. this was allowed to set.
I then opened the Fin part of the Fuz, cleaned it all up, and re glued the inserts and the fin halves together.
To ensure it was going to be strong I then glued a layer of 50mm wide kevlar along top and bottom seams, extending forward to cover the repair where the fuz had broken, followed by 2 layers of unidirectional kevlar 0° and 90°. it is a bit over the top, but on a DS model you don't want to take a chance, and I had the materials.

Then I started on the outside of the initial crack, thinned down the kevlar as much as I dared around the break and put a layer of 25mm wide kevlar along the break line again.

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then came the painful (And not so pretty) job of cosmetic.I added some 50g chop strand matt with epoxy and smoothed it down. I found an orange that is quite close and well we have what we have.

(note to self, get some painted fuz pics)

It has now been partially assembled, Elevator servo back in. Gyro and Jeti 2.6 rx added to the radio tray, just needs the tail faring, and servo cover taped on and balancing.

wdeighton

Then The Wing Repair
The wing repair looked easier, but was possibly more work.
There was allot of little damage. Some only seen when looking at an angle.
The de laminations where repaired by injecting thinn epoxy resin between the wing skins around the damaged area. This worked really well.

There was quite allot of damage from the Left flap servo bay and aileron. (Clearly seen in the top 2 pictures)
I got onto these next.
the spars looked and felt good so I did my best at cleaning around. I took both the Left hand servos out.
I then started by fixing the de lamination of the wing and drag spar by opening it up and brushing in as much resin as possible. followed by some carbon over a piece of foam in U shape so it was tying the skins into the the drag spar This was put in through the flap servo opening. That strengthend up the area allot. then it was the external repair to the top skin where the push rod comes through. I again sanded the area around the damage and lay on a piece of 100g carbon covered with mylar and as much weight as possible. Again I was quite happy with the out come of this. It only then needed some sanding smooth and painting.
The aileron was harder. I hade to try and free the pieces as much as possible, not to break them but so they would go back to their position, then using a mould form a good d80 wing I pressed it into shape after adding epoxy. This needed some extra sanding and building as in some places as the surfaces had gone in. I think the extra carbon was good to bond the pieces together too,

Leading edge damage was all sanded back and reinforced with 100g carbon and then sanded back.

Except for this
[smg id=27080]

This is where the Tip ballast decided to exit.

To fix this I decided to use this foaming epoxy Tony Fu has been raving on about. Mixed some up, and got as much in as I though was required, then a bit more.
[smg id=27081]
The wing was then taped closed, and left over night leading edge down to set.
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And again I was happy. The strength seems very good. you must remember this is a dynamic wing so as standard you cant really squeeze the leading edge (from say 5 to 10 mm back) but this seemed good and I have confidence there it will be strong.
[smg id=27083]
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The wing really now just needs some more paint. Halfords do an own brand purple that matches the d80 quite well. And after paint the wipers. I will add more on them when I get there. Some require more work than others. I need to get my method sorted. Tape seems to soft / flexible and Mylar the opposite. I have been thinking of using laminating film.

Hope this was work the read. and inspires some to get out there and fix and fly it again.

Will

Yoyo

Quote from: wdeighton on April 24, 2012, 22:08:54 pm
Hope this was work the read. and inspires some to get out there and fix and fly it again.


Well worth the read, thanks for making the effort to post it.

What did you use to take a mould from an existing wing? I need to patch up the D box halfway along one of my A3 wings and since it looks like a constant section in that area I was hoping to mould the other wing to reset the skin i the right place - it's mostly OK except where it tore at the sides and a bit where it crumpled. (That sounds bad - but probably 80-90% of the affected area is smooth skin still).

I'm using Polymorph to mould from one A3 fuse tail section to another as well at the moment (long story) but I wasn't sure if it would have the rigidity over large flat areas instead of small complex ones. (Interestingly this has shown that the moulded shape differed by 2mm or so in some places between the planes - surely they would only have used one mould in manufacture?)

I'm also thinking that the wing really needs some internal pressure to press the skin against the mould while it sets - how could I do that? Does the foaming epoxy press outwards enough?



Doing what you like is Freedom
Liking what you do is Happiness

deckit

Painful to revisit your Dynamics' damages, Will, but thanks for sharing.

Looks like you'll have the D80 ready for the imminent big DS winds :af
Well, they must be imminent, on the basis theyve been absent so long........ :''

Geoff N

Thanks for posting very interesting. Just started doing some of my own repairs
I'm not to sure about the different properties of carbon and kevlar. Can you tell me why kevlar for the fuselage and carbon for the wings?
That foaming epoxy looks good ,  how much is it and where do you get it from please.

wdeighton

Hi All

sorry for the late response.
For moulding I use many different things. More recently I have been using a really cheap epoxy resin from Alchmie. Its about £10 for a Kg, the hardener at about £15 a Kg, but the mix is 1 to 17 so it goes a long way.
For really cheep things that are small i use polyester as it is cheep. But unstable so not for a long term project. Just build it up slowly, as too think will exotherm too much and give shrinkage issues. peel ply bewtwwen helps key for a good bond.

As for carbon vs kevlar.
First I always use the same material for a repair as the piece is made from.
Kevlar bends, carbon, not so much. I never ever did get the point of carbon kevlar, you broken bits will be held together if you hit the deck.
Kevlar fuzz is more for 2.4 gig compatibility. why dont we use it in wings  $%&. it has a very similar modules to carbon, but carbon is used? I do hope to be able to answer this question one day.

Will

Spoons

Kevlar is really hard to cut and hard to work with, hence why carbon is used !
Although i seem to remember Muller using Kevlar in his models (I could be wrong though !)
Today Matthew I am going to be wing section MH32.

wdeighton

A couple of weeks ago, Whilst cleaning up the inside of my wing skin, I removed the little amounts of crus still holding the hinge together, which ment the aileron was unhinged from horn to flap  >:(

So I did some research, and found most people fixing with silicon, whilst I know its done, I have never been keen on it.

So in the true William way, I though of the most difficult way to do it. with kevlar.

I rotated the aileron opened and pushed a small screw driver firmley between the skin and drag spar, and jiggled ( rotated ± 5° to 10°) moved a couple of mm, did the same, moved a couple of mm, did the same, .....

And as I did this the skin started to de laminate, so i continued all the way to the horn.

Then I sanded the drag spar down what I believe is the thickness of the kevlar would be adding for the hinge.

I prep'ed a piece of 25mm Kevlar about 5mm shorter than the required joint.
Placed on a piece of plastic, poured some thin warm epoky resin onto the kevlar, and foulded the plastic over the top.
Out comes the decoraters seam roler the flatten it out as much as possible, and to wet the glass out as best possible too.
opeened it up and applied it.Taped and clamped the trailing edge, and into the hot box for the night.

Now Waiting............



Always unsure how these things will turn out. Never heard of people doing it, maybe there is a reason they don't.
but I will hope for the best. check in the morning!
:)      >:(      :)      >:(      :)      :D

wdeighton

Just to confuse people, These are the photos when I was proud of my paint job. This is the broken aileron mentioned above.
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Who would have thought.

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This it to show the colour match of the Halfords own purple compared to the D80. and also VW Bright Orange (I think) compared the the D80 Orange. Its not perfect but good enough for now.

[smg id=27095]

Bottom with halfords white primer and purple. Again not perfect, but good enough, and better than it was. I have learnt that you can't leave the primer. stuff sticks to it! so I have tried to spray it with some clear coat which helped.

[smg id=27094]

When it looked good.

I will take some pictures again when I get into the loft. Its taken a big step backwards cosmetic, but  :xx the hinge will be good.

deckit

Will, you've got it right, except to spend so much effort colour matching.

The hinge quality is critical, the colour match is irrelevant.

I look forward to seeing it at HH tomorrow........ (only kidding, I'll be there alone....) :''

wdeighton

The hinge is sound.  :)

Had a glitch, The first try I tried to hard to free it with out releaving the hinge line enough, and probably pusing in the wrong direction, so it delaminated allot wing side.  :banghead:
So I opened it up and put some gorilla ca in and put it back into its set position.
After 3 hours, I cleared the bottom of the hinge a bit, and I compressed the hinge (Lifted the surface up, not down), and it moved correctly, so I wiggled it a bit, cleared more out of the bottom surface, until I could open it enough to get the dremle in, then I ran a dremel along the back of the kevlar to loosen it. Cleared the bottom a bit more until I was happy with the travel, and "wha la".

All that's left to do is put the covers on the wing, radio tray back in the nose, balance and fly. (Maybe even tomorrow)
:xx

wdeighton

Flew on Sunday at the orm.
Like a Lead slead, but better.
Sown safe and sound and ready for the dark side
[smg id=27101]

wdeighton

Now I start again

A While ago I bought a D80 crashed from Geo. It was put into the side of RE at about 190 odd trying to get the magic 200mph.
I was going to fix it for him, but when we stated discussing possible costs, he got cold feet, and sold it to me.
Recently I have been feeling a hole in my fleet for a medium weight DS machine. So I decided to get stuck into this wing repair.

Both skins broke clean through.
I had split the skins into top and bottom a while ago.
Starting on the top skin by removed all the wood that was de-laminated / damaged around the break.
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[smg id=27288]

I tapered the side of the break over about 10 to 15mm,
the spar caps over about 100mm.
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I . removed all spars, and removed most of the micro balloon mix used to join this model.

then I started to put it back together.
Taped it into my fixture, Repaired the skins with a layer of 25mm 200g carbon tape, then a layer of 100g carbon behind the spar, and 2 in front. That went into the hotbox.
[smg id=27293]

I then added the balsa to replace the damaged parts.Over this I added the Spar cap repair. 10 tows foll length first, and then some tapered tows to get back to a thickness of 1.2mm.
[smg id=27296]
Then to reinforce the entire wing, I put a layer 200g carbon all over the back of the wing.
All this went into the bag and left on the hot box at 40° for 24 hours.

Now to do the other skin

wdeighton

So I have been back at it. Limited Pc access means I cannot post pictures.
So with the Mrs giving me job I find myself all inspired to fix models. I also had a big clean out leaving space and possibilities.
Not too much else to say.
Started fixing the wing skins. Removing all the broken bits, feather the edges, tape the wing together on the a surface and then start fixing. First fixing the a skin, then the spar, replace all the removed core layer and then repair the b skin. As the other side I added some extra carbon reinforcement in the way of 150g carbon and then some 300g x 100mm wide uni directional carbon to reinforce the spar caps.
I the bag and in the hot box.
I the removed the micro balloon epoxy mixture used to  hold it together and started to join the skins.
For sploog I used epoxy and micro fibers. And too deliver the sploog I used a cleaned out mastic gun cartridge. I mixed up 200g off resin and added microfibers until it was no longer. Runny I then applied a liberal amount to the spars and the profile. And all back in the fixture and in the hot box @50'.
Now to open it up and see how it looks.

It is however now at the back of the Que again and efforts back to the d100. This is now at half mould in the hot box curing but more about that in the correct thread.

wdeighton

September 01, 2013, 22:04:45 pm #15 Last Edit: September 02, 2013, 00:04:58 am by wdeighton
I pulled the wing out the fixture today and am quite happy.
It is strong very strong. Bit there is a weight penalty, but I expect it to be lighter than by other wind with 2 pond of balast in the tips.

There are some miss matches at the  the leading edge over an area of 100mm or so, but it is only 0.5 mm so could be filled and sanded in with out too much issue.

Left to do
   Cleane up
   Cut the surfaces free and re do the wipers
   Fit out.
   Fly

Saying that there is alot of work to do the fuz and stab.

The progress of this will depend on the success of the d100, it the mold comes out good, the project will stall while I finish of the d100.

Update of some pictures and some weights.
[smg id=27493]
Wing came out at 1.8kg

[smg id=27495]

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Should get a built weight of about 2.2kg

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compared to my 3.16kg on my tip ballasted wing

This wing is quite exciting for me because 2/3 the weight means I can fly it more often. I am hoping to get the fuz weight down compared to the one I repaired (went over the top)