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Old May 28, 2001, 09:20 PM
Registered User
St. Mary, Maryland, United States
Joined Dec 1996
8,556 Posts
Pedal Launcher Info?

I am building a pedal launcher after having a little excitement over the weekend flying my Mig-17 at a different field. I suppose the problem was the grass was a little longer/thicker than my normal field. Basically what happened was it got into the air at too slow a speed and immediately rolled 90 degrees and pitched up to vertical. Only quick reactions, full down elevator / left aileron, 450 initial watts of power and a LARGE helping of luck allowed me to recover at fly away.

In any case, does anyone have any pictures of their pedal launcher they would like to offer up? I have the box with about a 10 degree angle on the rails built, I'm looking for details on the pin - see-saw - etc. I can figure it out for myself but if there are any "Imporovements" that have become obvious with use please point them out!

Thanks
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Old May 28, 2001, 09:52 PM
EDF Head
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Stavanger, Norway
Joined Feb 2000
7,999 Posts
I use a home made version of this : http://www.gloeckner-s.com/GMT/engli...o/infokata.htm

Works great.
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Old May 28, 2001, 10:36 PM
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Lima,Peru
Joined Jun 2000
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Does anyone know who sells it in the US.
Thank you.
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Old May 28, 2001, 10:52 PM
gwh
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Fort Worth, Texas
Joined Dec 1996
1,610 Posts
Chris,

Take a look at my response in this thread: http://www.ezonemag.com/disc/Forum6/HTML/001029.html

There is a link to an article by someone else and a link to some pictures of mine.

I just made a c channel with 3 boards for the body. Then I drilled a hole through the side boards.

I drilled a hole about 1" deep in the sides of my see saw board ans inserted a 1/4" blind nut. A bolt then goes through the side of the channel and in to the blind nut on each side.

I used a long bolt going up from the bottom of the c channel as the trigger pin. The see saw board has a hole to clear the the bolt.

On the bungee I use a doubled piece with a large ring that floats on the tubing so that it stays centered. The large ring goes on the trigger pin. A small ring with a few inches of line then attaches to the plane.

The channel also has a hole so that it can be nailed to the ground.
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Old May 28, 2001, 11:08 PM
My dremel tool has no fear
Mark's Avatar
Reston, VA
Joined Dec 1999
353 Posts
I have got some pics and specs on the launcher I built for my K&A L-39 on my web page. Go here and look for pedal launcher.
http://hometown.aol.com/mantaultra/m...age/index.html
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Old May 28, 2001, 11:18 PM
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St. Mary, Maryland, United States
Joined Dec 1996
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Thanks Mark, glad I asked. I like the way your box is not too long and the rails and release extend in front. Makes for a lighter easier to carry arrangement.
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Old May 28, 2001, 11:26 PM
jrb
Member
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Edina, MN, USA
Joined Oct 1999
11,445 Posts
Chris,

Mark's picture is great.

The most important thing is to have the bugee ring secured a haed of the plane; rather than behind the plane.

If the ring is a head of the plane and the plane's ring should slip off, no damage if bungee is released. On the other hand, if the bugee is secured behind the plane there is a good chance for it to damage the plane's tail feathers (etc.).
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Old May 28, 2001, 11:38 PM
Scott Black, Montreal
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montreal quebec Canada
Joined Sep 1999
1,254 Posts
Quote:
Originally posted by Mark:
I have got some pics and specs on the launcher I built for my K&A L-39 on my web page. Go here and look for pedal launcher.
Geez - that looks like about $70 worth of hardwood! Mine looks like I robbed an old barn in comparison <g>.

But they work really well. I've been trying to talk Chris into it for a while. We've debated the ramp vs drag-on-the-ground issue many times.

I notice he's been strangely quiet this week <g>.

I slapped mine together in about 40 minutes and it looks like it. What I didn't foresee is that the airplane has to be far back to be behind the release and to have some ramp to accelerate on. The result is no room for your foot and you have to have a buddy stick his hand in there to press the pedal. Also, make sure you use a stiff board for the trigger. I used just a pine 1x2 and it flexes. The release pin is a bit rusty and sometimes the ring snags on the rust, the trigger just flexes and nothing happens. Very embarrassing.

For a pin, I took a bolt and turned off the threads on the end with my trusty lathe (another use for it!) so that it would release smoothly. It is inserted from the bottom and held in place with a nut.

Sketch it out and plan it (unlike me) and it will be easier to use.

sb
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Old May 29, 2001, 10:42 AM
Electriaddict
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Melville Saskatchewan Canada
Joined Mar 2001
1,579 Posts
How much bungee is required to pitch a 6 lb Jet? where can a guy buy that stuff?
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Old May 29, 2001, 12:18 PM
Scott Black, Montreal
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montreal quebec Canada
Joined Sep 1999
1,254 Posts
Quote:
Originally posted by dorysch1:
How much bungee is required to pitch a 6 lb Jet? where can a guy buy that stuff?
You want to have a force equal to 4 or 5 times the weight of the airplane. That ends up being a pretty heft bungee! Use the biggest surgical tubing. I would call around to find a medical supply house. You can buy real bungee chord from Crappy Tire but the problem with that is that it does not extend nearly as much. You get the pull for a much shorter distance.

If you have a bungee that strong - it might have to be 3 or 4 strands of 1/2" dia tubing - be DAMN sure that everything attached to it is up to the task - especially the stake in the ground. You don't want to get hit by anything should it let go. Ralph got his bungee in the back of the leg a couple of weeks back. Luckily his is not singing soprano. I would also keep onlookers away from the path of the bungee.

Let us know how it goes with the Tutor.

sb
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Old May 29, 2001, 12:53 PM
Electriaddict
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Melville Saskatchewan Canada
Joined Mar 2001
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I am not sure how to get that much surgical Tubing here in sask I don't know of any med supply places here I will do a search should be able to find something I'll build some good anchors 3 ft long and permanently drive them into the ground with some sort of an attachment on the end so the bungee can be attached when I get to the field tutor is coming along well just waiting for a speed controller
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Old May 29, 2001, 02:21 PM
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Houston,TX
Joined Mar 2000
1,217 Posts
I would suggest mail order from: http://www.hollyday.com/
Under rubber tubing they have both standard bungee and heavy-duty (45 lbs! pull).

I am using the standard bungee, the heaviest I have launched so far is 55oz - it leaves the bungee at 60+mph and I could still stretch the bungee more. I would suggest also buying grips from them and having them install them so you don't have to figure out how to attach the ends the hard way.
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Old May 29, 2001, 08:45 PM
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St. Mary, Maryland, United States
Joined Dec 1996
8,556 Posts
Quote:
Originally posted by Haldor:
I use a home made version of this : http://www.gloeckner-s.com/GMT/engli...o/infokata.htm

Works great.
Thanks Haldor, that is the one I have been using. It has worked fine except for this incident this weekend and one other where the trailing string snagged the elevator control horns Z bend. That is why I am finally going to this cumbersome box I have to haul around , to avoid the snags of the trailing string...
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Old May 29, 2001, 09:19 PM
EDF Head
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Stavanger, Norway
Joined Feb 2000
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I use a ramp in conjunction also - angled approx 10deg and 5' long. Flying speed is instant
The front end release ring is a good thing though.

Happy flying!
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Old May 29, 2001, 10:57 PM
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Houston,TX
Joined Mar 2000
1,217 Posts
I haven't done enough testing to really know that it works, but my current fix for the release wire whipping around and catching the tail is to put it in a nylon tube.
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