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Old Sep 30, 2003, 04:31 AM
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Learning to use a hi-start - Help for new pilots

I am making this post because I could not find tips or advice anywhere on the internet on how
a person, working alone, could learn to use a hi-start. I invite more
experienced sailplane pilots to add their tips, comments and advice to mine.

Hi-start launching.

First, let's be clear, I am NOT talking about competition launches here I am
talking about safe sport launches. I am sure someone will post about maximum
altitude and such. I just want to help you get in the air safely.

Second, get a coach/instructor if one is available and ignore all of this.
This is ONLY intended for someone who is unable to get help.

Third, your plane must already be well trimmed and flying straight and even
from a hand launch. Fail to this and the hi-start will turn your plane to
junk!

Fourth and very important, make sure your tow hook is in the forward most hole
that your plane has. It should be a little in front of the CG of your plane.
This will give you a more controlled launch than the more rear, competition
positions.

OK? We understand the goal here? Safe and gradual build up. Control, not
height!

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



Always launch into the wind. Launching is easier with a mild breeze than it
is in dead calm air. For learning purposes I would say you want at least 2-3
MPH and no more than 6-7 MPH of head wind.

I was taught to launch with all controls at neutral. In fact my initial
launches were with a little down elevator to help reduce the chance of a
pop-off. But I started with a full size hi-start and an instructor who made
the first 4-5 launches for me so I could watch and he could see how the plane
would behave. Then he released the plane on the next three while I held the
radio to control the plane. Then I released while he flew the plane. Then I
did both. But we were working with the BIG hi-start in a huge field and he
was there to guide me. If your plane is properly trimmed, all controls should
be at neutral for your launches.

You should only need rudder to control the launch. 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. If you get your angle off a little left or
right the plane will tend to go that way, just like a bad hand throw. Use the
rudder to get it back to center.

Build up to it slowly. Think of a hi-start as an assisted hand throw. Do
exactly what you would do on a hand throw. Basically flat firm throw.

I don't know what hi-start you have or how big it is, but if it is a "full
size" hi-start it probably has 30 meters/100 feet of elastic and 100-120
meters/300-400 feet of line. That is an awful big thing to handle on initial
launches without a coach.

If you are comfortable with large hi-start then skip this build up process.

You can either get an up-start which is 5-15 meters/15-50' feet of elastic
plus 15-50 meters/50-150 feet of line which can be used in a smaller space
and, in my opinion be a little less scary. Or, take your big hi-start,
replace the big length of line with a smalle length. You can cut a 50-100
foot length to use for your initial launches You can reattach it later with
snap swivels or just tie a knot.

Get a metal ring, 1.5-3 inches, that will allow you to loop the elastic onto
the ring in some fashion to secure it so that you are only using part of the
elastic you have to make the shorter launcher. Make sure the stake that you
put into the ground has a washer on it that will not pull through the ring.
Don't cut the elastic.

If you start small, say 10' of elastic and 30' of line it will be a lot easier
to control, and the launch will be lower and the energy smaller. Again, just
an assisted hand throw. We will use this length combination for this
discussion.

Pull back 5-10 feet, or about 1/2 the length of the elastic, for the first
launch.

Check to make sure all of your controls are working.

Stand firm and just give it a straight, firm, flat throw, controls at neutral.
You should only need rudder to control direction.

It should go out just like a hand launch, only with a little more speed and it
should naturally climb a little. It should just fly off the end of the line.
Don't go for height, go for control.

Build up the strength of the pull over several launches. 1/2 the length of
the elastic. Then 3/4, then the full length. Then 1.5 times the length of
the elastic. Build till you are comfortable. Then just slide the metal ring
further down the elastic and add more line. Use roughly 1 foot of elastic to
3-4 feet of line.

As the pull gets stronger, the plane will fly out faster and the lift of the
wings will take it higher naturally. No need to throw it up, it will go up on
its own. You can reserve aggressive angles and the more rear tow hook
positions for competition.

The Release

As you get past about 60 degrees you should be thinking about how you will get off
the hi-start. You can stay on till you are over the hold-down spike but it is usually better
to get off a little before that or the hi-start will be pulling you down.

If there is tension on the line, the hook will tend to not release. So you are going
to dip the nose a bit. The purspose 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 agressive 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 accelorate
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 have many launches with my gliders. I tell new pilots to launch flat with neutral
controls and the forward tow hook position. Using my smaller launcher (25'
tubing and 100' line) I get 100-150 foot launches depending on the wind.
With the larger one (100' elastic and 400' line) I estimate I go up 400-550
feet and can a little zoom off of the end if I want.

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 much steeper
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.

Like you I was afraid of the hi-start. If you had someone to coach you through the first
few you would be fine. If you don't, try this method.

That plane was made to fly. Fly it!

RC Glider Hi-Start Bungee (2 min 57 sec)
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Old Sep 30, 2003, 09:59 AM
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Joined Sep 2002
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aeajr stressed it, and I will restress that the sailplane needs to be well trimmed out before using a hi-start. The speed attained in launching from a hi-start will amplify the effect of any warps in the flying surfaces. This can make for very exciting launches, especially for a beginner. If at all possible, have your new sailplane checked out by an experienced pilot before attempting a solo hi-start launch.

Secondly, ALWAYS wiggle your sticks just before letting go of a sailplane on a hi-start. I use my nose or teeth to bump the right stick to insure all is operational. There is nothing more sickening then to realize you have just launched a "dead" sailplane. Unlike a winch, with a hi-start there is no pedal to take your foot off of. The hi-start will drag your sailplane down the field throwing off parts as it re-kits your creation.
Don't ask me how I know!

Sierra Gold
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Old Sep 30, 2003, 12:36 PM
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United States, CO, Colorado Springs
Joined Aug 2003
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On the controls:

1> Down elevator is your safety net:

If the plane gets squirrily on launch, a little down stick will bring it back in line. Too much down and you fly off the line-- frustrating, but safe. If it's really squirrily, odds are you're headed for tip-stall or pop-off, both of which can destroy the airplane.

2> Be aggressive with the rudder, and stay ahead of the curve:

If you throw off center, the plane (if left to it's own devices) will trace a beautiful semi-circle curving off in the direction you canted it until it slams nose-first into the ground. You prevent this by putting the rudder HARD-OVER to bring it straight back up the line. Beware, however, that you will almost certainly overcorrect the first few times, so be ready to send it hard over the other way. Again, a little down here will give you more rudder authority and help settle things down.

3> Elevator is *NOT* the key to more height, don't use it that way.

Up elevator on the high-start stresses your stab, creates drag, and increases the likelyhood of tip-stalling or popping off. This is especially true at the beginning of the launch. Don't do that. When you're ready for more aggressive launches, you'll get height by moving the hook and stretching the line.

4> If you pop-off, be aggressive on the elevator:

Popping off the hi-start is exciting- you're about to stall and tail-slide the airplane at low altitude. To recover, give it full elevator immediately when you hear it pop, and be ready to fly it out of the stall. That usually means full down and gritting your teeth while the airplane dives waaaay to low gaining enough airspeed to level out.
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Old Sep 30, 2003, 03:37 PM
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The voice of experience is helpful to new pillots, especially when we all agree. Thank you for adding your comments.

New Pilots who read these posts, please feel free to add your questions. We are here to help you.


Just another example video

First Art-Hobby Lotus Hi-Start Launch (0 min 30 sec)
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Old Oct 01, 2003, 01:59 AM
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The 'Wack, BC, Canada
Joined Oct 2002
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One of the biggest mistakes I see in pilots of all skill levels is not properley THROWING the model during any launch be it with a high start or a winch.

At higher tensions a level release will let the model speed up very fast and rotate to a nose up attitude very aggresively. This in itself can lead to a pop off. For this reason I like to launch my models with the nose up at a 45 degree or so angle.

But to do this safely you MUST assume the stance of an Olympic javelin competitor and THROW the model just like that javelin. You may get away with it for a while using the lighter poly ships but if the wind is a little wrong one day or you buy some new super ship and try to use the limp wrist launch it's going to stall and snap into the deck. When the line is under tension it creates a very high virtual wing loading and that is what let's your model glide "uphill". Take that high virtual wingloading for granted and it'll stall and snap in an eyeblink.

Find some pics of guys like Joe Wurts and others launching their models. Their feet are along the line of the launch and space well out. Seeing a shot of them with their model just out of their hands and you'll see the ending of a powerful throw and proper follow through.

I know it's hard to think and do a javelin throw with all that tension pulling at the model but it's important that you develop the right method now before it costs you your first molded ship.
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Old Oct 01, 2003, 07:34 PM
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Heart of Texas
Joined Apr 2002
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Thanks for the information. Never launched a sailplane with anything other than an electric motor. That will be changing as soon as I get my 1-26 hlg covered.

I've been planning on using a high (or maybe lower) start to get that heavy beast in the air so that I won't have to be heaving away every minute or two. Had no idea there was anything other than hooking on and turning loose of it.

Have never flown in the area where I now live. I've watched the buzzards though, and there seems to be pretty good lift much of the day. Looking forward to getting some airtime. Bet I'll be more successful now.
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Old Oct 01, 2003, 08:23 PM
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I am not familir with your plane.

The type and strength of the hi-start you use is determined by the weight of the plane and the wing span of your plane. A two meter ship can be launched with 3/16 to 5/16 tubing. A three meter would most likely require 6/16 to 7/16 to reliably get off the ground. 8/16 or more would probably be recommended beyond that. These are all outer dimager measurements ans assume a 1/16" wall. So a 3/16 ID plus two 1/16" walls equal 5/16" OD.

In some cases they rate the tubing by ID and thickness of wall.

My hi-start is 3/8" AND has a 3/32" wall as opposed to the usual 2/32" wall. It is rated for 3 meter and up but I use it to lanunch a 2 meter plane. I just pull it back less than the big planes do.

Be sure you are using the right hi-star/up start.

This might be helpful to read this:
http://www.aerofoam.com/complete_highstarts.htm

My advice is, when in doubt, go up a size. You can always pull it less. But if your hi-start is not strong enough your launches will be weak. You may only be able to launch with a 5 MPH or higher breeze.

My friend tried to launch his 2 meter Spirit with 1/8" bungee cord. It was totally inadequate to the job in quiet air and just barely put the plane up with a 5 MPH breeze.

I launch the same plane with a 3M hi-start and get great launches. I just don't pull it back very far.

If I had a 5/16 OD based hi-start I would be pulled back further. It would give a "softer" launch because the tubing pulls back over a longer time/distance giving a less sudden acceloration. Many people prefer this kind of launch. It is easier on the plane but requires more room to pull the hi-start.

All points for your consideration. Go up a size when in doubt.
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Old Oct 01, 2003, 08:29 PM
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If this is a very heavy plane, and impractical to throw, I have seen people winch launch 18 pound scale gliders using a little wheeled cart. They hook a harness to attachment points on either side of the cabin.

I don't see any reason why you could not do the same thing with a hi-start, but you would be talking a VERY strong hi-start for an 18 lb plane.

What are the specs for your plane?

Can you hand throw it?
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Old Oct 04, 2003, 08:50 PM
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Heart of Texas
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aeajr, If your questions are directed at me, I'll be flying a DAW Schweizer 1-26 HLG. It's EPP and 59 inch span. Weight should be in the 20 oz range with a wing loading of about 6.75 oz. per sq/ft. It is'nt that heavy, just a lot heavier wingloading than built up stuff (vs. 3.5 oz or less on the Skybench Lil Bird 2).

I know that this plane isn't a likely candidate for extended flights with just a hand toss. I plan on getting one of Skybench's Mini Hi Starts. It'll save the arm and back. I know that a larger set up might be better with the weight of the plane, but this one will be better than me throwing it and will still be usable in the areas that I will be frequenting.
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Old Oct 05, 2003, 12:59 AM
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How high do you get in a high start launch? And how long is the flight after that in thermal-less conditions? I have 25ft of 3/8" surgical tubing from my Control Line combat days ( use them as fuel tanks - they really stretch! ) ...if I combine them with 50-60ft of line...how high can I launch a 40oz 72" glider?

Thanks

Shane
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Old Oct 06, 2003, 06:06 AM
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As a new glider pilot this is very helpful - many thanks for the advice. I recently bought a little 1.2m hand launch plane and fitted a tow hook. A few weeks back I went to the local park with a short field high start and learnt through a couple of terrible near misses how to get the plane up safely.

My first attempt involved releasing the plane at a 60 degree nose up orientation - the poor thing squirmed side to side and I almost lost it wing first into the ground. After repeating this mistake I realised I needed to get the nose down more in launch. This resulted in much safer launches, but I was also using ailerons rather than rudder to steer her up, and holding up elevator to try to gain maximum height. I guess these are instinctive controls to make, so I'm very glad to get this advice from you folks.

Hopefully you have saved me a smashed plane (at least at launch - still plenty to go wrong). I'd also be interested to know how long I should expect to get in dead air conditions - seems like the plane comes down very quickly.

Peter
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Old Oct 06, 2003, 07:11 AM
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Quote:
Originally posted by culiv
aeajr, If your questions are directed at me, I'll be flying a DAW Schweizer 1-26 HLG. It's EPP and 59 inch span. Weight should be in the 20 oz range with a wing loading of about 6.75 oz. per sq/ft. It is'nt that heavy, just a lot heavier wingloading than built up stuff (vs. 3.5 oz or less on the Skybench Lil Bird 2).


This is a pure guess, but I would think 1/8-3/16" od tubing should send it up nicely. Is there a tow hook of some kind on it where you can connect the hi-start? If not, you will have to add one and reinforce that location to spread out the pull.

If you want to use a smaller unit, you might uses one of these up-starts as reference examples.

http://www2.towerhobbies.com/cgi-bin...rt&FVPROFIL=++

My friend is launching his Spirit 2 meter with a Dynaflite HD hi-start. The Spirit has built up wings and balsa fuse. It weighs about 30 oz I think. We had it out over the weekend and using 5/16 tubing on his dynaflite hi-start he was getting nice gentle launches to good height. I think he has the HD.

http://www2.towerhobbies.com/cgi-bin...=++&search3=Go
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Old Oct 06, 2003, 07:23 AM
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Quote:
Originally posted by shaneyee
How high do you get in a high start launch? And how long is the flight after that in thermal-less conditions? I have 25ft of 3/8" surgical tubing from my Control Line combat days ( use them as fuel tanks - they really stretch! ) ...if I combine them with 50-60ft of line...how high can I launch a 40oz 72" glider?

Thanks

Shane
Height is a function of line length, wind conditions and properly matching the power of the hi-start to the plane.

If you have 100' of elastic and 400' of line, you can reach 400-550' on your launch. A little breeze actually makes for higher launchs as you get a kite effect on the plane.

I would say your 3/8" tubing should be plenty strong for your 40 oz plane. It should be able to handle 100 feet of line and perhaps more.

My practice up-start has 7/16" tubing which is really a little strong for my 2 meter 30 oz spirit. When wind conditions are light, I only use 100' line. If there is a 5mph breeze or more I add 50' of line. With that combo and a little zoom at the end I estimate I am getting 200+ foot launches.

How long can you stay in the air? That is a pilot talent issue combined with the plane and the current air conditions. 2-4 minutes might be a good range on a no lift flight from a 500 foot launch with a lightly loaded plane and a competent pilot.

Flying a radio controlled sailplane off a "Hi-Start". (2 min 55 sec)
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Old Oct 11, 2003, 09:41 PM
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One of the things I do, especially with my up-start is I have part of the line removable. 25' of tubing + 100 feet of line works fine. If there is a nice breeze, sometimes I can add another 50' of line. I have it set up with fishing snap swivels to make it quick and easy.

If you have a larger hi-start but don't have enough room to pull it far enough, remove some line, as I did above, then add it back when you have the room.
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Old Oct 21, 2003, 03:10 PM
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Thank you all for sharing your tips. I'm sure reading this and a couple other threads have saved me from crashing my glider.

> If you throw off center, the plane (if left to it's own devices) will trace a beautiful semi-circle curving off in the direction you canted it until it slams nose-first into the ground.

Throwing on center is not as easy as it sounds, at least for me. So far out of 8 high-start launches with my Spirit I think 6 have started out with the plane making a sharp turn to the left. On the other two launches it went almost straight up after I released it. Haven't crashed yet as the rudder is quite effective in getting the nose pointed in the right direction, but is is disconcerting and the plane wastes a lot of energy going sideways that could be used for going up instead. I figure I loose 100' of altitude on the curved launches vs the straight ones.

I think I just need to practice more at throwing the plane straight ahead with the wings level. I can do that with no trouble for hand-launch glide tests, but doing it with the highstart pulling on the hook is a whole new ball game. Maybe I need to start lifting weights or something .
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