The P-51 Mustang

My best guess is that after the finishing resin had been applied, it was wet sanded and  moisture from the wet sanding had been absorbed by the non water proof alphatic glue used to join the sheeting pieces.  After the epoxy paint, the moisture was trapped inside and dissipated slightly each side of the joints to the sheeting glue, also a water based glue.  I'm betting now that if more time had existed between the wet sanding and the epoxy paint... the moisture would have left and ther'd never been a problem.  The curling didn't show until some time after the painting.

At any rate, it appears that the wing can be salvaged.  In a couple hours, using the heat gun I had the sheeting off a quarter of the wing, a flap and aileron.  The wing and control surfaces will need re-sheeted.  The fuselage is in reasonably good shape except the addition of some fiberglass cloth on fore section evidently needed because of fracture.  It appears to have been added after the painting however... leaving a question to what happened and why the tape was applied outside instead of inside... oh well, it had to be me that did it.


 If one clicks on the pic for the larger image and looks carefully, the joint problem can be seen... the underneath of the wing was worse and the starboard wing half that has the sheeting removed was really bad... hence why starting there, eh.

The plan is to resheet the wing and cover with Ultracoat rather than try to paint again, though the fuselage will get a new coat of paint, likely aluminum or silver.  One reason for film covering on the wing is this plane has concealed control horns and linkages which include four bell cranks in the wing.  Older modelers know that they can be notorious for trouble and I'd like to have an easy path inside.  The bell cranks could be trashed for four servos, some thought will be given to that.  Power will be an HB-61 PDP. 

Have worked some on the Mustang and have the fuselage near ready for paint.  The plane required a lot of wet sanding to get the epoxy paint layer mostly off.  There is a gel coat underneath and it is easy to see when the sanding enters it. 

Servo tray, linkages, fuel tank and motor mounting are finished.  Remaining on the fuselage,
The wing is where the work is, and new balsa sheeting is ordered.  The good news is that once the sheeting is done, covering with Ultracoat is a lot easier than painting.

note: good fortune provided discovery of all the parts of this plane as they were scattered in several different old boxes of junk parts.  The opportunity for something to go missing was strong.

Last thing done this evening was to check the preliminary balance and it appears that a lot of nose weight may be needed, however neither the muffler or battery pack were mounted and the plane will aslo need a one inch longer composite prop rather than the wood so that will help.  Also there is quite a bit of paint to come off the wing yet with three quarters of the wing sheeting left to remove.  Will go back at the fuselage once again with sand paper to lightened tail.


Have decided about the bell cranks... will leave them.  Even though they get sheeted over, with plastic film covering it won't be impossible to get to them.   The advantage is that it allows all the control rods to be hidden, course the hidden control rods could still be maintained if going with servos on all controls, but that would necessitate inspection plates to the servo boxes.  The current box is built and in the center of the wing and waiting two servos and hookups.

Curiosity got the best of me... had to go check the balance with the muffler and battery pack and it came forward quite close to the balance point.   The servo tray is only slightly aft of the balance point and was set leaving enough space to access the battery forward under or above the tank but the tray could be moved forward some and removed when installing the battery.

Progress Stalled  (mid march)

I've re-sheeted the flaps & ailerons and one wing quarter.  Waiting now on an order of contact cement from Sig.

A couple of days later, core bond adhesive arrived and progress resumes with another quarter panel finished... leaving the bottom of the wing to go and one half of it is stripped of old sheeting and ready for new.  Of some concern is that leading edge and wing tips, which have the epoxy paint yet.  I am in hopes of not having to sand it all off but am concerned about the film covering sticking to it well.  Will likely use the Sig product heat activated pre covering treatment. 

I do not know what adhesive the leading edge sheeting was installed with.  It does not release by heating with the heat gun.  With the resin and epoxy finish it offers a lot of strength.