主翼如何連接??[求助]

Alex Chan

Dear Julian,

You have tried inverted fight with my 1:3.75 voll GFK ASW28.

As you'd said, the lift is very weak in Summer. So assume no lifting force act on the wings. The friction between the steel bar is good enough to hold up the wing.

Don't be afraid just do it. But I strongly suggest not to try inverted fight in scale, since it's too danger.

The thermal ability of PG' 28 is ok, I've tried once in Long Tam. I don't know much on HF'28.

In my opinion, the most important is not the thermal ability of your plane. For a sailplane which can take off suffessfully the flying field is very important.

You can't expect a 1:3.75 ASW28 can lift up to sky from yur hand. It need "runway", the distance for the sailplane to accelerate to a minium speed which can lift you plane up. It's the most dangerous time for a large sailplane, ortherwise you can take up via aerotow.

I'll not fly bigger than 1:4 scale ship in Summer, because it's too danger.

Call Chan Chi Ping, he will give you some advice of your HF.

Good luck , good flying & happy landing.

Alex Chan.

Julian

Thanks for the advice, Alex. I couldn't agree more about the big scale sailplane. Taking off is the biggest concern. I need a good head wind and good helper to launch, which I don't have either.

Back to the subject. In normal flight attitude, part of the lift vector is acting inward toward the fuselage, due to the dihedral of the sailplane. That's what pushs the wings tighter. But in inverted flight, the dihedral becomes anhedral, the very same lift vector now is pulling the wings away from the fuselage. Of course I don't think it will pull the wing joiner rod away, but it could make the incidence pegs (the small rod) slip out of its place, if you make it too short. Same concern for some violent maneuvers or turbulence. I normally install a tension spring, as most manufacturers recommended, just to feel comfortable.

Alex Chan

After you'd ruined the wing, you'll find the joiner of the wing component remain horizontal. So there is no problem of lifting component. Assume the joiner is perellel to the wing. Due to a few degree of diahedral, the resolved component of lifting force toward the fuselage is small compare to the friction of the wing rod + the lifting force component. The similar reason for inverted fight, the lifting force will decrease as speed decrease, so the component of the lifting force awary from the fuselage even smaller. So don't be  afraid just do it.

As many people use a spring to hold the wing,  as I'd said the wing will not slip out due to friction. But the adverse effect of a spring is one will seriousely damage the fuselage due to hard landing, (the wing cannot slip out to release the internal energy) or the wing rod will be banded. Thus really bad.

jinn.tsai

The vibration force had split the wings of my FVK Skylark at joiner after aileron linkage breaking. Then, fell down in two pieces.