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Hi-Start vs Winch - Area Needed ? ?

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Old 12-12-2012, 12:12 PM
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Default RE: Hi-Start vs Winch - Area Needed ? ?

This may be useful:

> Learning to use a hi-start


For a typical thermal glider launch, hook goes between 1/2 and 1/8" in front of the CG. The closer to the CG the steeper the climb and typically the greater the height. Steep climb at a moderate rate of speed. The steeper the climb the more the stress on the wing, but with a properly sized hi-start gliders typically handle this quite well.

For a zip, usually the hook goes near the nose. Plane goes really fast with little climb, as in the video. When you come off the line you pull up and turn the speed into height. A very sharp pull up canput a lot of stress on the wings.

Natuarlly you can go somewhere between depeding on your goals. the key is the closer to the nose the more speed, less climb on the line. Closer to the CG the steeper teh climb and the less the speed of the clim.

Put it 1/2 way and you will be somewhere between those two extremes.

On my winch launched contest gliders the hook is almost on the CG and can stand on the pedal. But my woodies can't take that.

My less strong sport gliders might have it 1/4 to 3/8" in front of the CG and I don't push the winch as hard, or I use a hi-start.

I only use zip starts on my Zagi flying wing. There the hook is about 2" back from the nose.


For typicaly HSlaunches from near the CG, for a 2M glider I would likely use 5/16" latex tubing that has 1/8" walls or something like that. As covered in the article at the links above, you want 3-6X the weight of the glider in terms of pull for a typical hi-start launch.
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Old 12-12-2012, 02:48 PM
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Default RE: Hi-Start vs Winch - Area Needed ? ?

Ed,
I'll note this info and visit the references provided.
Winter has arrived here in CNY and the hi start rubber does not agree with the near or sub-freezing temps. It's time to breakout and preflightmy E-sailplanes for winter R/C flying.
Many thanks again Ed for your quick response with this info.

Art ARRO
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Old 12-12-2012, 04:59 PM
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Default RE: Hi-Start vs Winch - Area Needed ? ?

Art,
What you doing in a sailplane thread, thought you was a jet guy
You still at 4990? If so I'll giva you a call.

Harv
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Old 12-12-2012, 05:14 PM
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Default RE: Hi-Start vs Winch - Area Needed ? ?


Quote:
ORIGINAL: Art ARRO

Ed,
I'll note this info and visit the references provided.
Winter has arrived here in CNY and the hi start rubber does not agree with the near or sub-freezing temps. It's time to breakout and preflightmy E-sailplanes for winter R/C flying.
Many thanks again Ed for your quick response with this info.

Art ARRO
You might want to consider the OneWinch - temps don't bother this. You can adjust to any length you like.

OneWinch - www.onewinch.com
If you don't need the super power of a ford long shaft winch or you want to avoid all the walking of pulling your hi-start out to 800 feet, take a look at the Onewinch. I have one. Works like a winch in the space of a winch but about the power of a hi-start. No battery, very light and easy to use. And a LOT less walking than a hi-start.

Posted several posts/reports starting on bottom of the page.
Videos on this page - around post 158.
ESL Newsletter - Go to the 4th post for the report
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Old 12-13-2012, 05:48 AM
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Default RE: Hi-Start vs Winch - Area Needed ? ?

Hi Harv,
I fly sailplanes in the winter during the off-season of jets. I'm currently designing a turbine-powered sailplane to merge these two interests.
Yes, I'm still at -4990 but will be traveling later this week and the weekend.
Happy Holidays.

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