Tony Banfield

Thank you gentlemen for your prompt and informative replies.  I have used heatshrink/iron on covering many times in the past and they certainly produce the goods initially.  However, I have found that they lose their tautnes quite quickly and do little to enhance the model's strength.  Nylon, on the other hand, is fantastically strong and never loses its tension once doped and fuel proofed.  It is more hassle to apply but more than makes up for it in strength and durability.  I have to admit one has to be careful not to allow it to warp or distort the structure though.

For an aircraft/model to be longitudinally stable the CG must be forward of the centre of lift (or to be a bit anorakish aerodynamic centre).  This will cause the aircraft to try to pitch down.  This is opposed by the tail plane with a downward force (negative lift you might call it).  A flat plate tailplane does this by being at a negative angle relative to the wing.  This is called longitudinal dihedral in some quarters.  Now, a flat plat aerofoil is less efficient at producing lift (positive or negative) than a cambered one so some aircraft, such as the Jet Provost, actally have the tail aerofoil "upside down" and the F4 Phantom has little slats on the underneath of its tailplane!  With our models, because of their tiny Reynolds numbers, It is fairly irrelevant what section you use on the tailplane but flat plate is so much easier to build that the benefit analysis mods often results in this being the preferred option.

I am just about to begin covering the new creation with nylon.  I have used nylon many times in the past and have used balsa cement as the fixing medium.  However, it is now practically impossible to source balsa cement so I am going to have to use something else.  I was toying with the idea of using diluted PVA brushed ono the structure but I'M not sure that this would work as I don't know if it would have "grabbed" sufficiently before the damp nylon had returned to its dry state.  Does anybody out there have any suggestions/opinions?

Craig, I have found the most accurate way to deal with this problem is to use impact adhesive like Evostick.  Cut the sheeting roughly to size (accurately where it has to butt up to something else),  lay it in place very accurately and then pin it in position on the mainspar with a pin at either end and possibly one in the middle,  Then remove it keeping the pins still attached to the sheet, put a bead of adhesive on the spar and each rib and on the leading edge.  Replace the sheet and make sure that adhesive is transferred onto it so that both structure and sheet has adhesive on it.  Let it dry for 10 to 15 mins and then carefully replace it on the spar using the pins as accurate locators, then using an old broom handle or something similar, roll it forward and it will stick.  Be very careful as you will only have one go!  It goes without saying that the structure must be accurately supported, warp free, before you do this as, otherwise you will build in warps.  Of course, it is a good way to build in washout if you want.  I have used this method for several years and have never had things part company (even when the rest has ended up finely divided).

Furfther to my last post; I have found that, rather than trying to actually melt the film (clearly a high hazard technique), it is sufficient to heat it just enough to weaken the adhesive bond.  If you then pull the film off before it cools down, it comes off fairly easily leaving no pigment behind.  The masterclass methed is to pull the film whilst actually using the heat gun.  Have I burnt myself?  Nearly, but not quite.  I have been pondering if my wife's hairdryer would do the trick.  I havn't had the courage to find out yet!

Thanks everybody for your helpful advice.  I have started to have some success by using a heat gun very circumspectly, it certainly comes off more readily.  I shall try the brown paper and meths once I have got the bulk  off.  Thanks once again.

I have been trying to remove solarfilm from an obechi veneered wing and it isn't going very well!  Does anyone know of a way do do ir painlessly?