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Old Jan 31, 2001, 11:30 AM
Giddy up!
Sal C's Avatar
Woodridge, Illinois
Joined May 2000
4,478 Posts
Bungee assisted hand launch resources - videos?

Does anyone know if there are any resources available that demonstrate how to bungee launch, hand launch (with bungee), and plain old hand launch? (although I haven't had problems so far with normal hand launches)

Does the Electric Airshow video have any of these launches in it?

I don't fly at a field where others fly e-power and really don't get to see any of this. I saw a picture of Jim Ryan and an assistant bungee launching (via hand) his Skyray in MAN, I would like to see that type of launch "in action".
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Old Feb 01, 2001, 12:07 AM
Registered User
Tullahoma, TN
Joined Jul 2000
986 Posts
The Electric Airshow video has good examples of all types of launches. (I'm assuming you're talking about the 2000 San Diego Winter Fly-in video--excellent video.) I'm a hand launcher of my Kyosho F-16 and all my other belly-landers--I like the convenience and have never needed to go to a bungee. I'll tell you what, the video shows some pretty scary-looking, high-speed bungee launches of EDF models--it really allows them to climb out quickly, though.
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Old Feb 03, 2001, 05:07 AM
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Jim Ryan's Avatar
Cincinnati, OH USA
Joined Oct 2000
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Sal, there are lots of different styles of bungee launches, depending on the type of plane and the pilot's preferences. The F4D bungee launch you saw Don Belfort and me executing in MAN is pretty standard. We're using 16 feet of 1/4" latex tubing, with soldered keychain loops at either end. The anchor is a simple tent stake, and the bungee hook on the plane is just ahead of the LE of the wing (note that for these planes, you want acceleration, not altitude, so the hook is father forward than it is on a sailplane).

To launch, Don holds the model at a slight nose-high attitude, I run up the power, and when I'm satisfied with the sound, I shout "Go!" and Don lets the plane slip from his hands. With the Skyray, I hold full up elevator, because it wants to settle. If everything goes right, it skims over the stake about 3 feet off the ground going hell bent for election, and the fun begins.

For smaller S400 models, the bungee can be as simple as a "zip-cord" made up of #64 rubber bands linked together. At the other end of the scale, Kevin Cox uses a pretty fearsome triple(?) bungee cord to catapult his F-15 into the air. He and Chris True prefer launching the plane off the ground - sometimes with a dolly to hold the nose up.

The ground launching cradle popularized by Pat Tritle and others is a pretty neat device that lets one guy fly planes that would normally require an assistant. I know the "siege engine" type catapults have their supporters, but for me, this looks too much like work, and laziness is the reason I fly small models in the first place.

Like bungees, hand launches depend on the plane. With my little warbirds, I add 3 or 4 clicks of up elevator trim, run up the motor and give the plane a light level toss; staight is more important than hard. The plane will settle slightly and then start to climb and accelerate. I remove the up trim and start flying.

For planes with higher wing loadings, I might heave it with full strength from a dead run. It all depends on the plane.

Two rules:
1. It's very hard to throw the plane too hard on the maiden flight. You can always throw softer on later flights.
2. Straight and level matters more than hard; even if you or your assistant soft-arm the throw, you can always just let it land and try again. Don't try to FORCE it to fly.

Jim
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Old Feb 03, 2001, 08:48 AM
Giddy up!
Sal C's Avatar
Woodridge, Illinois
Joined May 2000
4,478 Posts
Thanks Jim.

I received the "Electric Airshow in the mail yesterday and watched it last night. Not too much bungee stuff but I did get to see the hand bungee launch. It looks kind of risky. The Stoli Mig was launched twice using this approach but it looked as if it was starting to roll over and would smack into the ground. Maybe it was the plane but it sure didn't look convincing. The pedal bungee launch seemed to be much safer although the model seemed to want to bounce, it looked to me as if the bungee was too long and the weight of the cord actually pulled the plane back down to the ground and bounced it. Maybe length and thickness depends on the model.

I wanted to get a look at how this was done before I attempted anything on my own. I also think I will hang around various flying fields this spring/summer to see what shows up.

Thanks again.
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Old Feb 03, 2001, 09:41 AM
jrb
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Edina, MN, USA
Joined Oct 1999
11,328 Posts
Where' Luc? Remeber his bungee system and its GIF movie posted on his site ( http://www.geocities.com/lucchev/bungee.htm ).
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Old May 03, 2001, 02:13 PM
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Irvine, Calif USA
Joined Feb 1999
12,009 Posts
Some hand-launches:
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Old May 03, 2001, 03:53 PM
Super Senior Member
Albuquerque, NM
Joined Feb 2000
3,396 Posts
I have a bungee hook in my DH-88 Comet, which weighs in at a hefty 3.5 pounds ready to fly. I dont think it would get up there if I hand launched it At any rate, I am still fearful of the pedal launcher only because if things go wrong, they go terribly wrong. I have seen more planes chewed up and spit out by pedal launchers that I generally lean towards hand launchable planes.

BTW, my DH-88 pulls off the pedal launcher, drags on the grass for about 20 feet, then gets up off the ground
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Old May 03, 2001, 04:45 PM
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Irvine, Calif USA
Joined Feb 1999
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When I discussed the pedal launch option with one well know German edf flier and builder, he said that almost all catapult launched edf planes he had seen had been eventually destroyed in a launch gone wrong.

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Old May 04, 2001, 03:39 PM
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Bernard's Avatar
24100 Sainte Foy des Vignes / France
Joined May 2001
122 Posts
hi

You can see some bungee launches with plunge
http://multimania.com/bungymania/

videos (EDF jet, Twin-jet, T33 ...)
and building instruction
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