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Ugly Mustang strip and rebuild, can it be rescued?


Jon - Laser Engines
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10 hours ago, Jon - Laser Engines said:

But, i think there is hope for this one even if i end up replacing most of it. 

 

It'll practically be a new one anyway, by time you're done!

 

Cannot do a cluttered workbench. I'm far from OCD about it, it's just the practical aspect, a bench full of junk ceases to be a useful bench and instead becomes a dustbin. And if a thing doesn't have a proper home, it rapidly becomes junk...

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2 hours ago, Jon - Laser Engines said:

True enough Nigel, but in mid battle the place is a mess. After that it gets a clear up

 

A massively useful tactic from the world of full size is the use of stackable FOD trays (foreign object / debris), anything loose goes in one and they can quickly and easily be stacked out the way; they are used religiously, but then again we also have random bench audits and a bit of a telling off if loose bits are found lying about

 

in our less professional world, I find empty 2L ice cream tubs invaluable (and as a bonus they come full of ice cream), one or two of those keeps all the widgets for 'the current battle' out of harms way, and makes the bench easy to clear.

 

I also like the 'build bin' and 'burn bin' system (shamelessly borrowed from the professional carpenters world), they stay handy for big and small (respectively) offcuts to go in.

 

It's so much nicer not having to clear away before each job!

 

Sorry. Back to the ugly stang...

Edited by Nigel R
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3 hours ago, Jon - Laser Engines said:

True enough Nigel, but in mid battle the place is a mess. After that it gets a clear up

 

Completely understandable!  But if one's builds are more like wars of attrition than set-piece battles, then tidy ups do need to happen every now and then!

 

Edited by Jonathan M
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That is in fairness a 5L tub. A lot of ice cream. I like salt and caramel.

 

Cut out the gourmand bits, and the 100 liter bin, as a receptacle , does the bench, as in a palm sweeps in the sweepings.

 

Thats where my 4 mm hex went, or it teleported to his bench. I suspect my 1/16 AF hex followed in sympathy.

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Right then. 

 

Another day and a half of work has things progressing quite well. 

 

First, i dug around in my retract box and dug up the old retracts from my galaxy mustang. Although servo operated these will work fine here and it saves me spending any money. Oleos are another story as finding some 170-175mm long to suit 4 inch wheels seems to be a problem. HK offer some at 168mm, but they only take 90mm wheels apparently so that might not work. I will attempt to call unitracts on monday but i dont hold out much hope. 

 

Here are the units in question. 20211211_171050.thumb.jpg.17906ed8a98d781ef7ea2299d599778c.jpg

 

With that out of the way i wondered how to fix the wing. Fitting new spars seemed like a right pain so i just used cyano to glue everything back together so it was strong enough to handle and not falling to bits each time i picked it up. I then sanded the front faces of the spars/shear web remains (it should be noted the kit has the shear web grain running spanwise so its virtually useless) and made some new shearweb/spar combo's from some cheap old ply i had in the corner. This ply is the nasty bnq stuff and it was left over from paneling the inside of my shed. I would have used 1/16 brich if i had any, but i dont and i wanted it done so 4mm bnq ply will do the job fine. 

 

20211210_154715.thumb.jpg.4eb88dd0ff60992e316c9901299d00ce.jpg

 

These were then epoxied onto the front of the existing spars

 

20211210_162057.thumb.jpg.eb53deb1cc368afc667c6275f4d8cd08.jpg

 

With this done and dusted i made up some new nose ribs from balsa and fitted these 

 

20211211_150857.thumb.jpg.e30397922e0d3bc3b971b5da144e4394.jpg20211211_150903.thumb.jpg.6f212e1fbd9fc01cc549bf8dd6f27cd3.jpg20211211_150909.thumb.jpg.97e28b7233e955a11d49e7e9e58fa8f8.jpg

 

A dummy retract plate was also knocked up for gear fitting purposes

 

20211211_160817.thumb.jpg.f91a13863098778628cdcf20917e4449.jpg

 

20211211_160822.thumb.jpg.d3b5cb732001a33ded24f42bf57299dc.jpg

 

Once the fit was good these were copied over and reproduced in 1/8 real ply

 

20211211_155834.thumb.jpg.3942311ada376316c5c1a13b36b1289a.jpg

 

More adjustment of the plate position was done and light 1/8mm balsa guide rails were tacked on with cyano. The ribs were then epoxied into the wing

 

20211211_172242.thumb.jpg.e06fa00407d5e13e705f042dbcf87bc8.jpg

 

and the gear should fit something like this

 

20211211_174851.thumb.jpg.2b94c903307864689e61184e7642e6db.jpg

 

 

Plenty more to do but i cant really go much further without the oleo legs so that might put the wing on hold. Not a bit problem, the fuselage still needs more paint stripping 😞 

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  • 1 month later...

Been a little while since i gave the mustang a hammering but i am now back on the case. 

 

The outer retract plate ribs and the plates themselves are installed and awaiting the oleo legs. Once i get the legs i can fit the units, retract servo, and then make an inner rib to suit. 

 

20220129_115452.thumb.jpg.791fd796acb8cd0863d3fe166148a1cf.jpg

 

Next on the agenda was the trailing edge. While structurally sound it was in the wrong place for scale and left me with tiny little flaps that didnt really move much. A few rough measurements had things measured out and after some chopping the new trailing edge was installed. 

 

20220129_115459.thumb.jpg.e2cd33a1c7f0c62d4d69f27b3bd9be54.jpg

 

You can see how much it moved by the position of the old torque rod hole. 

 

20220129_115509.thumb.jpg.3eb84f58c8d8aea2ca605221d5f508df.jpg

 

Next i stripped the flaps and ailerons before gluing them together to make them one long piece

 

20220129_124848.thumb.jpg.cfa6ed522146a6206a1d4d463051f2ed.jpg

 

This was then offered up and marked so i know where to cut it and turn it back into a flap and aileron again 

 

20220129_125625.thumb.jpg.55237649d68274bd95664b984999eb75.jpg

 

 

The outer end of the aileron needs extending but i cant do that until i fit the new tips. The flap obviously needs its leading edge sorted out to match the new trailing edge profile. Its very apparent how small the flap was and how large the aileron was vs scale. Not sure why they did this but it is what it is. 

 

Next thing will be the wing tips and flaps, then i might be able to start putting the back half of the wing back together. 

 

One thing i am toying with is glassing the wing as some of the sheeting is in a real state and i will not get a good finish with film. The structural integrity of the sheeting is also marginal. The problem is the open structure and i am considering filling these open pockets with expanding foam and then glassing over the top. This will also mean i do not have to try and rebuild all of the missing wing ribs as i can carve/sand the foam to shape using the existing structure. Once it has glass cloth over the top it will be plenty strong enough. I just hope i never crash it as then the club folk will get to see the horror inside!  

 

 

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  • 2 weeks later...

A rubbish weekend for flying means more mustang. 

 

The wing tip extensions have been glued on and the original wing tips stuck back on the end. This makes the wing the right span for the fuselage, i hope. I then trimmed the old tips to a more scale outline and moved on to the control surfaces. 

 

My original idea to lengthen the outboard end of the aileron was scrapped and i decided to lengthen the inboard end of the flap instead. Overall area of each would be the same however i did it, but it was better to make the flap longer for placement of the aileron horn and a few other things. The flap then got a new leading edge to make it wider and suit my new trailing edge. With all that done they were all given a single placeholder hinge to see if it would all work and things seem ok. It looks more like a wing now so that is good i guess. 756537479_20220206_1327411.thumb.jpg.d1d4d2e65cf0b92b323bbf8bae1f8988.jpg

 

The other jobs were stripping the covering off of the rudder, elevator and tail as well as hacking the guts out of the severed forward fuselage. The latter was a rather agricultural affair with hammer and chisel but we got the job done. This can be cleaned up and then it will become the cowling. 

 

Onwards!

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Just now, Nigel R said:

I admire your tenacity Jon.

 

Is it the 160 or 200 that's going in this?

 

160 is the master plan. It will have plenty of power, but the 200 might have visitation rights for testing that as well. 

 

As for the rescue, the only thing that saved it was the composite fuselage being in good condition. If that was as bad as the wings then it would have probably been on the bonfire. I was toying with the idea of getting some foam wings made for it but i didnt have any ribs in one piece for the profile at the cranked leading edge so i had to work with what was in front of me. I am also trying to finish it with minimum expenditure as it is never going to be a prestige model. 

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I am wondering if its owner was partial to some fish and chips as the paint finish and application method does look a little like its been dipped in batter. Its certainly thick enough. 

 

One question i did have was how nitromors or similar would treat the resin in the f'glass fuselage. Some of the paint is very hard to remove mechanically due to the shape of the thing and i am getting through abrasives at quite a rate. I just dont want the fuselage melting into a puddle on the floor. 

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You could always try Nitromors on a small, easily repaired section of the fuselage.  It's pretty serious stuff and to be used with some care but I doubt if it will attack totally cured fibreglass - especially epoxy based (although your fuselage is probably the cheaper polyester-based).

 

You'll probably save considerable weight - that paint looks thick!

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Minor headway this weekend as i was feeling lazy and didnt do much. 

 

But, i have managed to sort out the oleo legs through the week and this has cleared a major hurdle as i can now set about the undercarriage and getting the wing back together. 

 

in the end i was forced to make my legs as hobby king didnt have any that would fit my wheels and a £100 price tag for new was more than i was happy to pay for a beater of a model like this. 

 

So, a rummage behind the mill revealed a small offcut of ali left over from making laser backplates. A sketch up in cad gave me the shape, which was printed and cut out. This was drawn around on the material and out came the tools. Hacksaw, files and belt sander for the outer profile with the middle chain drilled before finishing with a hacksaw and file. 

 

20220214_120858.thumb.jpg.d7093c815019edd8edc3528b4c9a4aba.jpg

 

Top holes for the leg and cross holes for the axle were drilled and a set of oleo's i had in stock were modified to accept my new cranked ends. These were then pressed together and jobs a good'un

 

20220214_120650.thumb.jpg.559d96c610395ad5ddc3f16035e175fc.jpg

 

I can tart them up a bit later with come cosmetic work but they are functional and ready to go just as they are.  🙂 

Edited by Jon - Laser Engines
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While they could have been a smidge longer i think these will do fine. Now i just have to put everything back together. 20220214_185239.thumb.jpg.05843172faa3527a200de0b0680a09bb.jpg20220214_185248.thumb.jpg.b1bb4581ad3748dc20e82f3fc052b01b.jpg20220214_185358.thumb.jpg.a3c768af7942e4f4e4cb7d2856996c19.jpg

 

 

While i had the wing on i decided to see if the wings are still straight after all the surgery so i whipped out my incidence meter. With the tail at 0 the left wing was 0 root and -1 tip, which seems reasonable. The right wing was +1 root and +1 tip. So i need to decide which is correct and try to make it all work. I would like some washout, but if its easier i may end up with no washout but even incidence. 

 

 

The root cause of the issue i think is down to the wings being fractionally misaligned when glued together so i might be stuck with it but the wing locating dowels are also pretty sloppy in the fuselage so i need to look at that as well. 

 

generally though i am pretty happy as the wings are mostly straight so i can keep going. 

 

 

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  • 2 weeks later...

Another non flying weekend means more Mustang and it has been very productive with two major milestones reached. 

 

First, the retracts are fully fitted and working with the last of the support ribs installed along with the retract servo and pushrod. Its been a while since i last set up mechanical retracts and my sense of nostalgia was met with an almost equal sense of 'oh yea, this is why we dont use these any more'.  

 

As a starter for 10 i had to do open heart surgery on a futaba retract servo as it had a chopped lead for some reason. A 148 with broken gears was on the organ donor list so a new lead was quickly soldered to the board. A mount was knocked up and pushrods manipulated until everything worked as it should. The uplocks are not 100%, but the downlocks are so that is all that matters to me. 

 

IMG-20220226-WA0001.thumb.jpg.980c305d20bb0ee34cd164bdd87f8cf7.jpg

 

 

Once this was all sorted i cut out the ply ribs for the other end of the plate and they are currently drying. 

 

IMG-20220227-WA0001.thumb.jpg.9d23a4985d7f3067ee260f5db0ce7e53.jpgIMG-20220227-WA0003.thumb.jpg.c1be430bba8ecd83c7a03ea901229b2c.jpg

 

The 2nd milestone is i have finally got the paint off of the fuselage. I started on this while the servo plate for the retracts was gluing and it has been an ongoing chore all weekend long. I found that an 80 grit flapper landing disk in my dremel was the least soul destroying way of getting the job done and so it was duly done. After about 2 hours i gave it a once over with my palm sander, and with the joint effort of the two seemingly destroying not only the paint but every nerve in my hand we had the job 'done'. I still need to go over it with some wet n dry on a block to level things off but that will wait until the weather warms up as its too cold to be outside with wet hands. 

 

IMG-20220227-WA0006.thumb.jpg.dadce2cabc47c14fe78ed35a3b2d5542.jpg

 

There are naturally a few small areas that need paint removal but in general we are back to the original paint. Panel lines also need to be cleared out but that is not too bad a job for a round permagrit file. 

 

I also cut a notch in the fin so i can recreate the fin horn balance as on the full size, i modified the profile of the rudder so its closer to scale, and have applied filler to the tail ready for sanding back. Once sanded i will glass the tail, then sand it with the rest of the fuselage, then primer...and so on. 

 

The wings too are ready to go back together and i just need to place an order with a model shop for some supplies. The wings will be glassed as the top sheeting is a mess and the glass will help hold it all together. 

 

So hopefully i can now stop cutting things apart and instead start getting them back together. The cowl still needs paint stripping and loads of the glass work, but if i can get the core of the airframe together then i will be more motivated to tackle that. 

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