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Joined: 10/6/2003 From: black mtn, NC, USA Status: offline
Cracks in the fuse that need to be repaired and possibly areas that need more reinforcement when the new fuselages are laid up. I'm going to fill back in the old engine and retract cutouts using foam as it will be easier to shape back to the original contours. There is some pretty good cracking at the seams in the tail and I'm going to cut the old fuse right down the middle after the engine and retract cutouts are done. I'll then secure the two halves to individual pieces of white board.
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Joined: 5/4/2003 From: brisbane, AUSTRALIA Status: offline
I would worry about spliting the fuz to put onto boards. The distortion may be difficult to manage. May be better to use splitter board?
For a project like this I often make a very quick splash (thin) mold to lay up a heavy plug in - this gives a much more stable suface to get a good finish on. When doing this I simply fill cutouts with blocks of foam and cover with 2" wide sticky tape. The heavy plug then allows finer finishing of these details.
Making the extra throwaway mold may sound like more work however the joy and time saved working on a more solid plug soon make up for this. I have often gone the 2 mold method when resurecting a favourite crashed balsa model - glue back together - sticky tape and plasticine over the divots - quick mold - heavy plug- mold number two - and turn it into a fiberglass job.
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Joined: 3/13/2004 From: Vista,
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quote:
ORIGINAL: propbuster
I'm going to cut the old fuse right down the middle after the engine and retract cutouts are done. I'll then secure the two halves to individual pieces of white board.
I think you will have a very hard time getting the mold halves to match. I thought of doing it like that, and have come up with a way that should work. However, it involves making a plug from scratch. Maybe you could adapt the technique. No guarantee that it will work though.
I would start by building a half fuselage on a profile crutch, like the old Guilllows models. First, I would cut two identical profiles from 1/8 lite ply. Then-and here is the crucial step- I would stack the two profiles and the two mounting boards together. Then I would use a drill press to drill holes for alignment pins through the stack. I would also put holes about 1/4 inch outside of the profiles for the mold alignment pins.
Next I would build left and right fuselage halfs on the pre-aligned profiles. I would then put the two halves together with pins in the alignment hloes for the final finish.
Attach each half to it's pre-drilled base, and lay up the molds. When the molds are cured, drill the alignment holes from the back of the backplate through the holes you drilled in the first step.
I have actualy started doing this for a 45" Yak. Other projects, and the need for domestic harmony, have stalled it.
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Joined: 10/6/2003 From: black mtn, NC, USA Status: offline
Well, Thanks for the advice guys about cutting the fuselage (especially navav2002)! But it's all a little too late, as I've already cut it this morning before checking for comments. First off, after the cut, the firewall is still firmly attached to the seperate halves and there is no deviation in the two contours there. The rest of the fuse from the firewall back to right before the vertical stab is very stiff and checking with a profile guage there is no noticable differences up to that point either. The vertical stab itself is a different story. The fiberglass is very flimsy and moves easily to the touch. Here's my plan to assure proper alignment and identical shapes of the two halves. I'm going to trace out the centerline profile of one of the halves correcting for where the wing fairings need to be squared back up caused by the exsisting cracks. Allowing for the thickness of the fiberglass itself, cut two identical pieces of white board that will sit inside each fuselage half. These "inside" boards will then be each attached to their own slightly larger piece of whiteboard which I can then mate up and mark and drill for alignment pins. I will also make formers (two identical at a time) which will be placed on top of the "inside" centerline boards, at the same places, to stiffen up the vertical stab area and assure the same contours along the length of the fuselage. Working from the inside of the individual halves will be a lot easier when it comes to doing the crack repairs, and working inside the vertical stab while the fuse was still one piece was nearly impossible due to the thinness of it. I'm fairly confident that this will work, and well, that's my plan at least!
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Joined: 10/6/2003 From: black mtn, NC, USA Status: offline
Filling in the engine and retract cut outs with foam and rough sanding for now. Also the cutouts for the horizontal stab will be filled in and redone as the previous owner hacked them up and covered up the resulting gaps with fillets. Also, not having the original wing that came with the fuselage, it seems that the NACA 18 airfoil is a good match at the wing saddle and decided to go with that when repairing that area of the plugs.
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Joined: 10/6/2003 From: black mtn, NC, USA Status: offline
Here's the two identical boards that the fuselage halves will be attached to. I think I'll come up with someway to be able to put the two halves together for the plug prep and painting and then seperate the two for making the individual mold halves.
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Joined: 10/6/2003 From: black mtn, NC, USA Status: offline
The boards now attached to the fuselage halves. They straitened out the slight twist in the tail section and made the fuse a lot stiffer to work with. The two halves mate up perfectly and now I can really get to work on them. The vertical stabilizer is going to need a lot of filler to get it perfect and I'm thinking that the fuse as it came new, wasn't all that great to start out with! Very flimsy to say the least.
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Joined: 10/6/2003 From: black mtn, NC, USA Status: offline
Not a lot to report, except a lot of filling and sanding going on! Once I get it a little closer to perfect I'm going to use a laminating epoxy to finish it out. Anyone have suggestions on how best to color epoxy? Also, I have the templates for the wing ready and will be cutting the cores soon.
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Reproduction of Curare Fuse Project Thread - 
