UH60 Crewdog

I have notice recently that many new comers to high performance EDF jets want to hand launch. I dont know there or even my reasoning when I first started into them. But I want to start this forum to allow people with horror stores to express there regrets and reasons for switching to a bungee system for there landing gearless aircraft. Post pictures or video links for the misguided souls who have not found the beauty of latex... No pun intended

Nitroaddict

I have a silly question. How are you able to be sure that the plane can get enough altitude before hitting the stake the bungee is tied to?

I have a Kyosho Illusion EDF that is a bear to hand launch and thought about making a bungee for it, but was always concerned that it wouldn't get enough altitude before reaching the end, and plow into the bungee stake at 40mph!

My solution that I was thinking of inside my head was to launch downhill, but I wasn't sure about this either.

UH60 Crewdog

At the point the bungee no longer has pull and becomes completey contracted the metal ring will slide off the hook that is attached to the plane. A simple "L" hook design with a heavy key chain loop should be enough for your illusion. To get the right tension on the bungee for a launch use a fish scale and pull out until it reachs appoximatly 20lbs and place your planes launch point there. I do not use bungee from the metal ring to the launch pedal because it will pop the airplane when released. A little up trim and you will be airborn in just a few feet. As for hitting the stake, drive it low to the ground so it wont pull out and hit you or most importantly the plane!

Vettster

I use Thera Band instead of silicon. It doesnt break in the cold and comes in many diffrent colors each representing its strength. I use the Extra Strong(Black) for my HET Jets and for the foamies I use Green. Its also less than half the cost!

A good lesson I learned the hard way is.....Never thottle up before you release the bungee! You will disconnect from the 'D' ring!
And.....if someone offers to help by releasing the bungee for you, Make sure you explain to them, when you release, Do NOT! pull back like a sling shot. This will release the 'D' ring from the plane aswell.

Releasing the 'D' ring is not good cause the end of the rope will WHIP or catch your plane and reck it. Trust me, I know! Simply let go and half way down the shot, go to full thottle.

mark660

will hopefully do my first bungee this w.e

Vettster

What kinda plane are you launching. Make sure the hook is well ahead of the CG.

mark660

it all went well the plane is a het f20

UH60 Crewdog

Happy everything went ok mark! Any advise to add to here on your setup will only help others.

tallyho88

My Feedback: (2)

Glad all went well with UR bungee start. You have answered a question I had about bungee starting my E-Flite BAe Hawk. I shall place the L-shaped hook where the nose wheel normally goes!!! Just ahead of CG. I plan to use PVC rails stuck in the sod at an inclined angle...at 15-20 degrees?
How are things in Perth? Gov General BURT was my mothers cousin!!!
Norman McKinstry

rcmiket

This one works well for me. Bought all the stuff at Home Depot. Mike

Larry Dudeck

My Feedback: (1)

http://www.rcgroups.com/forums/showthread.php?t=404254

This is an article I wrote a few years ago. It deals with the physics of bungee launching, takes away any mystery

rcmiket

Hey that's pretty informative. Thanks Mike

tallyho88

My Feedback: (2)

Many txs RCM. This is exactly what I had in mind!!!Some questions: 1. How long was your bungee>? Did U use monofilament with ring?
2. What is diam of PVC? Is that black Insulation on runner rails>>/?
3. Can this be handled by a single person...or is help needed?////>>????
4.Is bungee anchored at ground level.????
On another blog...Canadian member said he uses Thera Band. What is this?? Do U use it???


PS. What is total length of launch rails???
Norman McKinstry

rcmiket

The Bungee is 2- 10 foot lengths of surgical tubing from Home Depot
Then 2 1 inch rings and some nylon cord ( length depending on the hook placement.
Bungee's at ground level
One person can launch it no problem.
The Pictures I posted were the original since I have modified the launcher. Here are the pictures of it now. If you have any question let me know.Mike

rcmiket

One more thing I got rid of the PVC insulation due to the amount of friction it was causing. Mike