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Old Oct 09, 2012, 03:04 PM
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Actual hi-start launches:

RC Glider Hi-Start Bungee (2 min 57 sec)


Bungee High Start Glider: Perfecting the Balance (3 min 19 sec)


http://www.youtube.com/watch?feature...&v=JGvhxIICR48
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Old Oct 10, 2012, 03:14 PM
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Here's another one. 71 oz model launching to about 250' with little to no wind. Old Pinnacle hi start from NSP, not pulled back to it's full extension. It's a pretty heavy duty hi start, so we rarely pull it back as far as it will go.

Airtronics Legend Sailplane Launching from High Start (0 min 33 sec)
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Old Oct 15, 2012, 08:23 PM
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I just successfully tested my home built Hi-start It's about 40' of 1/4" silicone tubing and around 100' of 30# fishing line. It's a bit short, but my field is space limited. I'm flying a swap meet find CG Sophisticated Lady, SEEN HERE. The problem I'm having is that the plane is releasing to late. After launch, the plane starts to circle the anchor point and gets dragged down a bit before it releases. What's the usual cause of this, and what's the best solution? Thanks for the help.
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Old Oct 15, 2012, 09:26 PM
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After you get to the top of your launch you have to put the plane into a little dive and then pull back up so that the ring slides off the tow hook. Sometimes it might take a couple of tries until you get the feel for it.
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Old Oct 15, 2012, 10:05 PM
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Ah, so it's a technique thing. I'll work on it
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Old Oct 15, 2012, 10:18 PM
Jeff
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1) Make sure the tow hook has no angle to it
2) As mentioned, near the top, dive slightly for two seconds and then pull back slightly. As the ring becomes detached you might even get a slight 'slingshot' upwards from the energy stored in the rubber. However be prepared to give DOWN elevator right after that little extra upwards boost. Otherwise you'll ping upwards, stall, and then lose 30 or 40 feet.

It is all practice and timing.
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Old Oct 15, 2012, 11:49 PM
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Originally Posted by Bugman Jeff View Post
Ah, so it's a technique thing. I'll work on it
If you read the article on the first page the release is described. And you see it in most of the videos.
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Old Oct 16, 2012, 07:13 AM
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I'd been through the whole thread, and while the thread is packed full of useful information, the only thing I saw regarding actually getting the plane off the hook was this bit in the first post "You may use a little up elevator at the very very end to help release the ring from the tow hook, but
mostly I just let it fly off." My plane was being uncooperative and this wasn't working for me, so I asked the question
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Old Oct 16, 2012, 09:36 AM
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Quote:
Originally Posted by Bugman Jeff View Post
I'd been through the whole thread, and while the thread is packed full of useful information, the only thing I saw regarding actually getting the plane off the hook was this bit in the first post "You may use a little up elevator at the very very end to help release the ring from the tow hook, but
mostly I just let it fly off." My plane was being uncooperative and this wasn't working for me, so I asked the question
No problem. We want you to ask questions. I was just pointing you to other places that might provide useful information.

Then let me appologize. I have several versions of this thread posted around the various forums. What I pointed you to on the first page, in fact, is not there. So I have written it below and will add it to the first post.


Here is where you may be having a problem.

If there is tension on the line, the hook will tend to not release.

THE RELEASE

Once you have reached around 70 degrees in the arc, you dip the nose a little and pull up a little. The purpose of dipping the nose is two fold.

1) take pressure off the ring that is on the hook
2) allow the parachute to open thus helping to pull the line off the hook

For a relaxed release, what I call letting it float off the line, a little down elevator for a second or two should take the tension off. This is not a dive, it is just a little forward pressure. You should hardly notice when you look at the glider. The tension reduces, the chute opens and the line just floats off.

If it does not come off, then you follow this with a little up elevator. This tips the hook so the opening is facing at a small downward angle which will allow the ring to slide off.

For more aggressive releases you can actually use the last remaining tension in the line and the weight of the hi-start to gain a little extra height. This is called a zoom.

From a hi-start a zoom might be 25 feet. However on a winch the zoom can be good for 100+ feet.

In the zoom technique, which would be executed before you are over the spike holding the hi-start down, you dip the nose into about a 45 degree dive for about a second, then pull up to about a 45 degree climb.

The dive allows the weight of the hi-start and the remaining pull to accelerate your glider. When you pull up you translate that speed into altitude.

Caution: If you have a glider with delicate wings you can snap them on a zoom. Most gliders can handle this zoom technique on a hi-start, but if you are seeing wing bend as you go up the hi-start, don't zoom or you may break something.


I hope this was helpful.

As you become more accomplished, if you have an adjustable tow hook you can move it back till it is about 1/4" in front of the CG. This will cause a steep climb and a higher launch. But always watch those wings. If you are getting a lot of visable flex or bend of the wings you may not want to put the hook back that far.
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Old Oct 16, 2012, 12:08 PM
Launch high. Fly low.
United States, CA, Lake Elsinore
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Stuff that I learned here. Thanks for all the tips, guys.

Soar!
Jun

Xplorer 3.8 fun fly (1 min 26 sec)
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Old Oct 16, 2012, 04:26 PM
Jeff
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Originally Posted by jcats View Post
Stuff that I learned here. Thanks for all the tips, guys.

Soar!
Jun
That must be a decent sized hi-start. Saw a guy at SULA last weekend hand throw the same sailplane... 10 minutes later he landed. Oh he worked for it, but it was amazing. Wish I could afford something like that. Hell wish I could fly like that!

Nice catch.
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Old Oct 16, 2012, 06:04 PM
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Fantastic info, thanks
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Old Oct 16, 2012, 07:06 PM
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I have another question. In order to launch into the wind, my location is ideal. It's slightly uphill to the pin, and the field I thermal above is over the crest of the hill little hill(it's probably only a 30' rise). Too far for me to realistically get the plane with my skill level, not to mention walking to where I can see clearly is I do manage to keep the plane in the air. I can anchor the tubing much more advantagously, but then I will usually be launching with the wind instead of into it. What'll happen if I launch with the wind?
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Old Oct 16, 2012, 07:17 PM
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Old Oct 16, 2012, 10:21 PM
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When a Boeing 777 launches, with all those jet engines - he launches into the wind as much as possible.

When a Piper cub launches, he launches into the wind as much as possible.

When an aircraft carrier prepares to launch its catapult boosted, after burner running figthers, they turn the ship into the wind as much as possible.

When contest pilots with molded gliders set up their super powerful winches, they set them up to launch into the wind as much as possible.

So, when you launch your gliders from your hi-start, you launch into the wind as much as possible. Every other choice is a poor one if you have the opportunity to launch into the wind.

That should cover it.
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