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isoaritfirst

FS4 repair

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isoaritfirst

Some of you who were at the Welsh may have seen that My FS4 flew the 3 days held together with insulation tape, after a slightly skewed but gentle landing that split the fus open and damaged the wing root. It had been weaken in a previous at Bishops when flying very heavy. Damage was caused mainly by the wing crushing the fuselage.

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isoaritfirst

To repair I removed the servo plate, and cleaned out the nose to create a traditional 'boat' this has carbon tows all around its edge inserted during manufacture, Cleaning out I left a 2mm edge all around the opening.

The inside of the fuselage was all pushed back into shape and small wayward pieces warmed and manipulated back to their rightful places. Zapped and sanded back, then internally strengthened with two pieces of carbon cloth overlapping along the sides of the fus (to add strength against the wing crush), and a bladder used to ensure it made a great contact with the inner walls.

The outer area around the lip for the nose cone was ground down a little and new carbon tow wraps pulled around before binding tight with tape to dry. The whole fuselage was bound tight externally with insulation tape to ensure that the bladder didn't stretch anything out of shape.

I also made a hot box to dry it nice and hard. Hot box was a thermostatic controlled oil rad , a cloths horse, a fleece blanket....and positioned behind John while he spent the day playing on his computer. He got up occasionally to check it and revolve it - and was on fire watch.. It stayed a lovely warm temp all day with the rad set very low.

Several layers of 1/32 ply were inserted to form the new servo plate. The first 4 were under the carbon tows the next few between them, to give a flush final finish. I also added a couple of layers of glass cloth within the ply laminate and topped off with a glass finish to tie in the original fuselage side lips I had left intack.

The servo plate now extends back into the fuselage to add anti-crush. as it runs back I did take out its centre and also reduced the number of ply's - hopefully this has created a stronger but 'plyable' former that will give in the event of a V bad landing.

Painted and rubbed down to try to match original 'thin' paint look, and inner nose paint thinned more to allow nose to fit.

Putting it back together I have installed a magnetic switch so that the nose cone can be taped firmly in place on race day and left there all day.

The 2.4 aerials were poked through holes in a piece of epp which was then jammed down the side of the receiver. It holds one vertical and one horizontal and protects then nicely against damage.

Pics taken before final finish - which will be to run insulation tape all around the inner nose over the battery, receiver and wiring. Looks rubbish but Insulation tape is very much my friend, and adds a lot of strength by stopping the inner nose splaying out.

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thermaldoctor

Very nice work Mike, great job.

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isoaritfirst

Other thing that may be of interest;

Having put the two wetted out pieces of carbon inside the fuselage, running from the pre-carbonned area of the inner nose back to the wing joiner hole I was left with the problem of making a suitable bladder to insert.

I cut an old thin walled bike inner tube to around 5" long with the valve close to one end. The intention was to tie and glue with zap as small and as neat as possible and then push it down the fus before inflating. The problem was how to push it down the fus without dislodging the wet carbon. The space available was small and the inner tube big.

I came up with the idea of putting a 5" long small diameter rod ( I actually used a piece of plastic tbe)inside the inner tube before sealing the ends. I was then able to both push the tube and also and more importantly stretch it to reduce its diameter before pushing it into place, allowing it to relax back and then inflate.

Worked like a charm, and I went away feeling very smug for a well earned cup of tea..

Its these little problems and the random solutions I find that makes modelling so enjoyable for me.

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isoaritfirst

Strange init - that although I was a little gutted when I broke the FS4, I really have enjoyed repairing it, and possibly that is because it is for me a puzzle that I like trying to solve, if it was a plan of works that I had to do then it would simply be labour - which would be tedious.

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marillion

Good work mike. I have another broken fuselage i can send you. ;)

I enjoy that kind of work when i have the time to fix it. Coffee and music is important.

A cigarette would be good as well. But my wife won't allow it. ;(

Sorry for my broken english.

Greetings, Kai

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Janek

Sorry for my broken english.

Your written English is better than most natives, including myself :eek: :D

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Anthony Murphy

Mike,

Out of interest how did you stop the bladder sticking to the wetted carbon?

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John T

Mike,

Out of interest how did you stop the bladder sticking to the wetted carbon?

Anthony, regarding preventing stick, i was told to use an ASDA/TESCO (others available) type carrier bag, which i have used a number of times and proves very good and can be just peeled off and reused. Just make sure you use an unprinted section as the print remains on you repair.

John T

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oipigface

I was left with the problem of making a suitable bladder to insert.

Mike, I haven't actually tried this yet, but I have been thinking of using those party balloons that conjurers use to make animals out of as a bladder. Seems to me that these could be just placed in the fuselage and inflated in the usual way. I doubt though if they would exert as much pressure as an inner tube. Any thoughts about this?

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isoaritfirst

I sprayed the tube with pledge. I suspect that it would not have stuck anyway, but with the polish it came away without any sign of sticking.

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Gromit

Mike, I haven't actually tried this yet, but I have been thinking of using those party balloons that conjurers use to make animals out of as a bladder. Seems to me that these could be just placed in the fuselage and inflated in the usual way. I doubt though if they would exert as much pressure as an inner tube. Any thoughts about this?

I've tried the party balloons several times. They're pefect to slide down inside the fuz/boom. Problem is to inflate one of these balloons takes a lot of puff/pressure. Just try blowing one up yourself :mad: . Its also difficult to get the balloon to inflate properly where you need it to. The slightest rough edge of glass or carbon & it goes 'pop' too. Perhaps others have had more success than me though .

Stu.

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Yoyo

I've tried the party balloons several times. They're pefect to slide down inside the fuz/boom. Problem is to inflate one of these balloons takes a lot of puff/pressure. Just try blowing one up yourself :mad: . Its also difficult to get the balloon to inflate properly where you need it to. The slightest rough edge of glass or carbon & it goes 'pop' too. Perhaps others have had more success than me though .

Stu.

They seemed too easy to pop to me too, so I got the smallest cheapest inner tube wrapped in a carrier bag too when I needed it, worked very well and I could have easily put enough pressure on it to split the fuse.

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isoaritfirst

Yep,I also thought that it would be easy to put too much pressure in, which is why I wrapped the fuzz in tape.it also had to cover all the areas where the h tube may have blown out. I used a piece l of ply over the front boat area to keep the tube in.

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Bobbyr

Condoms?

Already epoxy proof ,

:eek:

Excellent advice regarding fuse repair though :clap:

Bob

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Rooster-X

Condoms?

Already epoxy proof ,

:eek:

Is what I always use, and sometimes for fixing Fuselages as well :D

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isoaritfirst

I had a few old and used inner tubes, can't say the same about condoms - but I guess a quick search around the park.....

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Yoyo

No need for that. We're a helpful bunch, I'm sure if you ask on here someone could send you some old ones...

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oipigface

I've tried the party balloons several times. They're pefect to slide down inside the fuz/boom. Problem is to inflate one of these balloons takes a lot of puff/pressure. Just try blowing one up yourself :mad: . Its also difficult to get the balloon to inflate properly where you need it to. The slightest rough edge of glass or carbon & it goes 'pop' too. Perhaps others have had more success than me though .

Spent the last hour trying to blow up party balloons inside and outside my Voltij fuselage. Much hilarity, but I think I shall see what I've got in the way of old inner tubes now.

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Gromit

Spent the last hour trying to blow up party balloons inside and outside my Voltij fuselage. Much hilarity, but I think I shall see what I've got in the way of old inner tubes now.

Jon, Not easy is it :D . gave me one hell of a headache for several hrs after too ..

Stu.

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