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Author Topic: rubber hybrid  (Read 505 times)
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Viperkite
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« on: April 06, 2019, 06:09:14 AM »

I have built a KK Invader that is scared of heights. As my rubber powered models always fly well, I thought about sticking a length of rubber in it with a small prop to give it a power glide. Has anyone tried this and how successful was it. If so has anyone designed a gadget to hold the prop until it releases of the tow.
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lincoln
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« Reply #1 on: April 06, 2019, 08:28:03 PM »

Seems like a longer towline would work better. If you're going to put a prop on, might as well make it a big folding one and set it up like an endurance model.

It sounds like you don't care much if it stays original. I suspect a thinner wing would improve the glide some. Even better, a thinner wing with an airfoil similar to those used on successful, recent FIH gliders. That is, in part, thin and with a fair amount of camber. Of course, you could improve things even more by making a skinny fuselage to use with the new wing...  ;-)

Have you tried a turbulator? This could be as simple as a piece of thread doped onto the top of the wing, probably not too far back from the leading edge. It's the kind of thing that requires experimentation. I've seen significant differences when used on a small RC glider I had. I used two layers of automotive striping tape in that case. The model was probably faster than yours, so your results might be different. Unfortunately, I'm not aware of a good article on turbulators, though I'm sure there are some. The ones I've seen are mostly a bunch of hand waving. If you wanted to get really technical, you could calculate the likely boundary layer thickness where you want to add the turbulator, and make it a substantial fraction of that thickness. But it's probably quicker to experiment. 

Anyway, the guys who read the towline glider section could probably advise you better. I have very little experience with towline free flight gliders, though I've flown a bunch of other stuff. I've seen a Lulu glide impressively well.
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Viperkite
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« Reply #2 on: April 07, 2019, 01:43:56 AM »

Thanks, I realised afterwards that I probably posted in the wrong section. It's just that I catapult all my gliders.
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lincoln
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« Reply #3 on: April 07, 2019, 02:56:21 AM »

The Invader is never going to be a good catapult glider.
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Viperkite
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« Reply #4 on: April 07, 2019, 04:21:58 AM »

Unfortunately I'm 'Billy no-mates', so have no-one at the other end of the string Cry
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billdennis747
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« Reply #5 on: April 07, 2019, 05:07:49 AM »

Bungee, but I have an Invader and I think it's a stinker. Looks nice.
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Viperkite
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« Reply #6 on: April 07, 2019, 06:54:40 AM »

As an Albert Hatfull design I expected better. I have his Senator as well and it his fantastic. The Invader has been disappointing.
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lincoln
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« Reply #7 on: April 07, 2019, 05:11:36 PM »

Unfortunately I'm 'Billy no-mates', so have no-one at the other end of the string Cry

I've seen articles with gadgets to hold the glider for you. I've also seen towline gliders launched with a mini hi start. A few feet of model airplane rubber and some string or thread. Recommend the latter if your field has woodchuck holes in it.
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Viperkite
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« Reply #8 on: April 08, 2019, 02:25:40 AM »

Thanks, that is the system I have been using, but apparently it has many names (Bungee, catapult, Hi-start etc.) very confusing.
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lincoln
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« Reply #9 on: April 08, 2019, 08:26:28 PM »

Thanks, that is the system I have been using, but apparently it has many names (Bungee, catapult, Hi-start etc.) very confusing.
A catapult would be very short and works primarily by kinetic energy, meaning that the glider will reach a high speed and coast upward. A good catapult launch would tear an Invader apart. A hi start launch wouldn't be all that much faster than normal flying speed.
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Viperkite
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« Reply #10 on: April 09, 2019, 09:40:04 AM »

I managed to snap the wings off with a hi-start. I got frustrated with it and pulled back way too much. Ironically it still travelled its usual distance.
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lincoln
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« Reply #11 on: April 10, 2019, 12:34:59 AM »

I hope it's repairable.

From what I hear, small gliders like this need very little rubber. Like maybe a strip of 1/8" FAI tan?
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Viperkite
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« Reply #12 on: April 10, 2019, 04:01:26 AM »

The beauty of stick and tissue is it is always repairable.
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