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Jan 19, 2009, 09:21 PM
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Build Log

Catapult Launched RC Glider

This is something I've been thinking about doing, for a very long time. Pictured is a Stray Cat 18, made from a kit produced by a local freeflight legend, Stan Buddenbohm. It is an 18" span, CLG, with a viscous timer actuated popup tail de-thermalizer.

Rather than build from scratch, I decided to convert this plane, because:

1. The park I fly at is too small for free flight, and this plane is just collecting dust.
2. The plane flies well, so I want the concept to have a fair shake, with a good airframe.

The initial stages are shown. I'm planning to use Falcon 1.7 servos, with spring return R-E. I'll be using .006" wire for the torsion spring, because the low torque of these servos. The receiver, a 2.5 gram job, is on order from BP Hobbies:

I hope this works.
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Jan 19, 2009, 10:03 PM
Throw a glider!
glider90's Avatar
Very Cool Mulligan! Those things will do about 90 seconds on a full grunt launch, so you should have plenty of fun with that. It sure will be a test of servo centering!

It is so great that radio technology has come down to where we can fly F/F style models with R/C units installed at the local park. I think allot of FF guys are starting to see R/C in a whole new light.

I know I love the fact that I can fly in the field next to my house rather than have to pack up and jump in the car. Sometimes I just trim the model to circle and watch it fly hands off, knowing if I hook a boomer I can bring it back to my feet.
Jan 19, 2009, 10:18 PM
ein flugel schplinterizer
seanpcola's Avatar
I would like to see some photos of the radio install if possible, Mr. M.
Jan 19, 2009, 11:49 PM
Transplant Chey WY from Reno
Thermaln2's Avatar
Mr. Mulligan,

I am in the midst of putting together a modified Hoosier Daddy and Pelicantoo Combo using the VApor Brick that will tie to my JR 9303. This is to address the Y-tail use I am putting on my bigger DLGs. The Brick has a tested range by me of over 600 ft (by GPS measurement) whihc is nearly our of sight for my eyes.

I hope to post a build thread when it's gluing.

Jan 20, 2009, 12:42 AM
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Thanks for the responses. I'm glad to see there is some interest. My roots are in free flight, because that was all I could afford, when I was kid. So, it is really satisfying to combine my first love with new technology. Here is what I've gotten done so far.
Jan 20, 2009, 08:01 AM
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LittleG's Avatar
This looks like an interesting and fun project to do, will be staying tuned.
Jan 20, 2009, 10:13 AM
Registered User

This Is Going To Be Fun!

I tried mini 6 & 7" span clg's this last summer with my grandson, has a blast!
It will be great to have them return to you when the grandson not there to chase them.
Jan 20, 2009, 10:15 AM
Transplant Chey WY from Reno
Thermaln2's Avatar
Yes the freeflight idea sounds good. A few years back I attempted to make the catapult stick attach to my TX at right angles to the antenna. Because I was not thinking as light as you, I found that I did not have enough rubber power to launch the plane, and it was difficult to hold onto the TX with enough leverage. I am looking forward to your solution. Back then there was an idea to use a ground mounted pole and a very long piece of rubber to launch straight up. I think that was a FF event also. When you look at the history of bungie launches with the foot pedal launch holder, we are seeing the obvious shrinking of planes.

Why not just cut off the CF tube at the elevator hingeline and have the moveable surface solid?
Jan 20, 2009, 11:05 PM
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Thread OP
Originally Posted by Thermaln2
Why not just cut off the CF tube at the elevator hingeline and have the moveable surface solid?
That is what I would like to do, but the short piece of carbon tube is adhered pretty well to the movable surface. I may make the surface from scratch.
Jan 22, 2009, 09:56 AM
Registered User

Another FF conversion to RC

Originally Posted by Mr._Mulligan
1. The park I fly at is too small for free flight, and this plane is just collecting dust. I hope this works.
Hey Mulligan,
First, I'm sure it's going to work!

Problem I found was in what you are saying that the park is too small for FF. That means if there is any wind at all the FF leaves the park which means weight and other considerations, FF's are not designed to fly upwind.

That don't mean it's not worth doing, but I found I have to wait for no wind conditions. I love flying my conversion using a JMP Rx and actuators from Bob Selman. The 1000' range is no problem at all.

A $3 plane with $85 of electronics!

I'm very interested in hearing about your flight reports.
Jan 22, 2009, 12:18 PM
Registered User
Cool, for sure.

The Oakland Cloud Dusters used to have a catapult launched FF event ... I forget what they called it ... that used a tremendous amount of FAI Tan rubber. It was pretty extreme. I watched one of these events in 1995 at Waegell field, the gliders were built quite reuggedly and would shoot off that cat at very high speeds. Probably in excess of 120 mph.

What are you planning to use as the "cat?" Something big or small?
Jan 22, 2009, 09:02 PM
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Thread OP
Originally Posted by Cap_n_Dave

What are you planning to use as the "cat?" Something big or small?
Nothing fancy. I'm going to get the surplus Tan Sport I have in the fridge, and just hold some in my hand, and add more and more rubber until I get a good launch. If I use the Tx neck strap, I figure I can handle it. We'll see. I may end up using the rubber motor winding stooge as a stationary launch pad, if I can't handle the Tx at the same time.
Jan 26, 2009, 10:20 AM
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Thread OP
OK, making some more progress. I decided to mount the servos on basswood "rails" with tiny screws. The Falcon servos do not have any flat surfaces to allow gluing. Also, I'm hoping the rails mortised into the fuselage sides, would help to stiffen the pod.
Jan 26, 2009, 11:56 AM
Gutless wonder
Guz's Avatar
I gotta ask, what/who's servo's are those?!?! Funky looking things.

Oops, never mind. Didn't look at the first post

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