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Old Oct 12, 2006, 06:20 PM
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Bungee launching...

So I have the bungee and pedal release, what now? What should I use to hook the bungee to my FA-18? Should I buy rails? What are my options? Thanks in advance.
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Old Oct 12, 2006, 07:08 PM
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Robert Belluomini's Avatar
United States, KY, Crestview Hills
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What bungee and pedal release did you buy?

Is it a JePe dolly style for example?
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Old Oct 12, 2006, 08:48 PM
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Quote:
Originally Posted by agustapower
What bungee and pedal release did you buy?

Is it a JePe dolly style for example?
It is the one on www.warbirds-rc.com site.
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Old Oct 12, 2006, 09:00 PM
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Plover WI
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I feel Danger
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Old Oct 12, 2006, 09:44 PM
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Originally Posted by Operator 88-94
I feel Danger
Thanks for the input, that really helped me with my question.
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Old Oct 12, 2006, 10:35 PM
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go to this thread, it will help...
http://www.rcgroups.com/forums/showt...ungee+launcher
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Old Oct 12, 2006, 11:38 PM
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Sorry if u take it that way ive seen to many people hurt someone or trash there planes without finding out all the input's such as making a ramp and what to set the ramp at as far as degree's and other things before they buy but on the rc forums just type it in and find all kinds of usefull stuff such as ramp or just winginging it off the ground or you will find alot of usefull info on the het f-18 where alot of them can handlaunch it if its setup correctly.

Scott
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Old Oct 12, 2006, 11:53 PM
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Quote:
Originally Posted by Operator 88-94
Sorry if u take it that way ive seen to many people hurt someone or trash there planes without finding out all the input's such as making a ramp and what to set the ramp at as far as degree's and other things before they buy but on the rc forums just type it in and find all kinds of usefull stuff such as ramp or just winginging it off the ground or you will find alot of usefull info on the het f-18 where alot of them can handlaunch it if its setup correctly.

Scott
That is exactly why I am asking on the forums. Finding out how to setup the bungee launch BEFORE I go out to the field.

Thanks for that link that was very helpful.
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Old Oct 13, 2006, 12:28 AM
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The most important thing to remember is no mater what ramp or launcher you use you must be prepaired to "FLY IT OFF"! Don't think that it will come off correctly each time! I have 400+ maybe a lot more launches then i can remember! I've lauched with and without a ramp and even no bungie just straight power up from ground! (no gear!) Just pay attention to the plane to correct any errors that you may encounter weither it's weather related(wind changing direction) or if for some unknown reason the cord snags on something be prepaired to fly it down to safety! After your hook has released from your plane power up to full throttle and keep her straight gaining altitude and speed!
Good luck and here's my panther without bungie! It's the grey & yellow one after the blue one!
http://www.rcgroups.com/forums/showp...&postcount=505
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Old Oct 22, 2006, 11:22 PM
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Here what I've learned that works for me. I built a rail launcher like the one shown on yourzagi.com. It's also the same type sold by Classic Flying Machines. I like this particular set-up as there is no trailing release line and ring to snag on the jet after launch.

First, with the set-up, I drive the bungee stake in the ground first and then stretch it out using a fish scale to set the correct tension. I then position the rail launcher and stake it only at the back. I don't stake the front until I have a straight line down the center of the launcher, along the bungee, to the stake.

When I'm readu to go, I:

1. Set the model on the rails.
1.A. If the model has an easy access hatch, I connect the battery now.
2. Test the radio, all controls and the motor.
3. I stretch the bungee cord to the release bolt and set it in place,
4. I now attach the ring on the leader line to the tow hook.
5. I now inspect the underside of the airplane to ensure the leader line is straight and not wrapped on the tow hook.
6. I now hold the release ring down, to prevent accidental launch, while I take the slack out of the leader line. and ensure the jet is positioned for a straight launch.
7. I now move behind the launcher ( and chase the lookie-loo's behind me, if necessary)
8. I call the launch.
9. I start my timer.
10. I feed in a little up elevator (1/8th to 1/4 stick throw).
11. I simultaneously step on the release pedal and jam the throttle full forward.

On maidens, I generally only have to correct a little with ailerons during the launch. I trim as necessary and enjoy the rest of the flight.


Rob
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Old Oct 23, 2006, 07:50 AM
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About the only comments I can make is make sure you are not standing on the antenna After stretching out the cord, give it some room to contract if either of the anchors lets go.

Bungee launches, for the most part, are safe and a sure way of getting your plane airborne. Just make sure the plane is balanced per the plans and you should have no problems. I use a ramp made of wood and the rails are covered with 3/4" pipe insullation. Using a fish scale I set the tension to 5 times the AUW of the plane. I launch with power off and apply power only after the hook drops away.

The launch hook is located between the CoG and the nose. Closer to the CoG results in a high, low velocity launch. Locate the hook farther forward results in a lower, flatter launch trajectory with more velocity. This is my preference.

The elapsed time between pedal release and cord fall-away is about 1.25 seconds. So you have little time to react to a bad launch.

Good luck with the maiden.
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Old Oct 23, 2006, 08:24 AM
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[QUOTE]About the only comments I can make is make sure you are not standing on the antenna[QUOTE]

Larry,
I KNOW that you weren't there when I did that very thing with my F-104 late last winter
Makes them glitch pretty badly with only 2" of antenna.........

-Mike
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Old Oct 23, 2006, 11:18 AM
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Cincinnati, Ohio
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Larry and others have made some very good suggestions and while it was subtly noted, there were one or two not mentioned. I have used several different types of launchers over the years...wood, shortened Zagi PVC with a ramp, pvc with padded rails, pvc with slick low friction rails, ground drag and the dolly system and they all work well, some better than others, but each one serves a purpose.

The Zagi was shortened to 4' for easier transport. The ramp launcher, made from a 1' x 4' white coated shelfboard worked well for flat bottom models like the HET-RC FA-18, where putting it on a rail launcher would have had the rails resting on the tailerons instead of the wings and causing excess stress to these control surfaces and servos.

The rail launchers worked better for models with bottom mounted wings, like the F-4D Skyray, Sniper, F-20 etc... and the wood launcher worked well with narrow or bottom humped fuselages like the F-4D Skyray or F-16. Ramp launchers would not work as well here because they would lean to one side on the flat table. As you can see, each one works best for a specific aircraft, so I would suggest you figure what you want to fly now and in the future and go from there. If you have the time, build and try them all as that is half the fun!

Lately I am using the Dolly system that agustapower Bob referenced and it is pretty much all I use now. There is less equipment to haul around as that got real old after a while, it is easy to set up, it works with any model (it got to be a pain switching the ramp to a rail to a ramp again every time), it buffers the ride with wheels, it has a better release system and it's more like a landing gear takeoff. It is also very low profile and less distracting to other fliers on the field. The only disadvantage is the possibility of the release cord tangling with the rear of the aircraft, but if you adjust the loop so it protrudes just past the rear of the aircraft, it will eliminate this issue. I forgot to mention, it is cheap to build as you probably already have some of the hardware in your hangar.

So for the most part, any of the methods mentioned will work well and you just have to decide which one you want to try first. No matter what you do though, just be sure to keep it fun!

Carl
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Old Oct 23, 2006, 06:37 PM
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Mike,

I think you are the first bungee launcher ever to admit to stepping on the antenna...but I suspect you are not alone in this...
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Old Oct 23, 2006, 07:15 PM
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Quote:
Originally Posted by demetrius
Good luck and here's my panther without bungie! It's the grey & yellow one after the blue one!
http://www.rcgroups.com/forums/showp...&postcount=505
hi demetrius;

in the second part of the video, did your father's panther
take of from grass? very impressive performance.

Do you happen to know
the thrust/ weight ratio of that panther?
something like 250 watt/lb???

thanks.
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