Jeffrey Hall

Thanks Pat.

Just a thought Pat, did you shrink with gun or iron? I wondered if the iron might cause the film to stick to the tissue as per comment from ED.

I was thinking I could tear off the tissue but not worry about the bits left stuck to the balsa. However after Pat's comments I think I will go for his method. I had already stripped the fuselage so that can be film covered in the normal way. I will probably start by covering the tailplane (less work to redo if I run into trouble). Thanks for your replies.

This is probably a really stupid question but here goes. I have a tissue covered glider finished with Ezy Dope which is looking a bit sad so I am planning to cover it in Hobbyking film. To avoid all the hassle of stripping could the film be applied over the tissue?

Simon Having looked at some of your photos methinks you are being too modest. In my mind I think I can engineer a third hook using the other two as attachment points without doing any butchering. Having said that I still haven't given up on correcting the CofG.

Invader photo as promised.

Simon Looks as if that accounts for the difference in our decalage measurements. I have compared my fuselage to the plan and can't see any problems. That still leaves me with the CofG problem. Paul mentioned that he had to pack the trailing edge on his Invader so I wondered if I might try packing the leading of the wing and adding some ballast instead of messing about with stab. The words clutching and straws come to mind. Failing that I will just have to bite the bullet and stick it on a bungee to see what happens. I'll try to get some pics done today but I warn you it is not a work of art. Thanks for all your help Jeff

Thanks for that Paul If you had to pack the trailing edge does that mean it was stalling? That would be the opposite of my problem. Do you know how much ballast you used? I have 15 feet of tubing for an initial trial and need to look in my fishing box to see what line is available. At the moment I am thinking that with the CofG so far back I will get a very poor climb.

Simon Please can your clarify what you mean by the incidence chord line being 3 degrees positive for that section. Does the line pass through the bottom tip of the trailing edge in which case it would pass about 3mm above the centre of the leading edge where I am trying to measure the decalage from? Perhaps I have misunderstood you.

Just noticed I quoted mg instead of gm and everyone was too polite to mention it. Must be an ultralite.

Simon I think the bands I am using are quite strong but I will try adding another pair to test the theory when the weather improves. I must admit I am always nervous when fitting strong bands to a tissue covered model.

Thanks for your prompt replies. Yes Simon, 40". I checked the decalage with a home made sliding Vs and digital protractor. However after your comments and having checked the plan I am beginning to doubt my readings, so I will have another go. I cant find any significant twist in the wing or tailplane and I was careful to pin down during shrinking and doing. The total weight is 215 mg, r/c conversion added about 95 mg so airframe about120 mg. I did a little beefing up in places so that would account for the extreme weight. Is the weight you quoted including ballast? Yes Pat, bungee. I have seen tales of folding wings so I added a little spruce to the centre of the spar. My thoughts so far are that I could be getting lift from the tailplane. I perhaps should mention that I modified the tailplane to have a straight trailing edge instead of leading edge so I could add a one piece elevator. However I can't see that this would make a difference, it is still symmetrical. Quite a mystery. Must go now because SWMBO tells me I am going shopping.

I have recently built a KeilKraft (Ripmax) Invader with 2 channel r/c. I flirted with twin rudders but was never happy with the outcome so I ended up with a single fin (and yes I can hear the boos). With radio fitted it needed 35gm of ballast to get the recommended cg. First test glides showed it to be nose heavy. There was zero decalage so I altered it to about 3 degrees (lowered leading edge of tailplane). Still dived. Next I remove the ballast, just leaving the radio gear. Now it glides nicely but the cg is at 2/3 chord. It seems that something is not right somewhere. I would like to launch from a high start but am wondering if it would loop off the top with this setup. Any suggestions gratefully received Jeff