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Old Apr 30, 2011, 05:58 AM
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United States, AR, Bentonville
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Build Log
Building an RC Airplane Launcher

So my next few episodes will be about building a functioning RC Airplane Launcher. My first attempt didn't go quite as planned, leaving my Easy Star in the repair shop. I'll be making improvements until I get it right, then post a how-to-build for all to follow.

What do you think? Any improvements/functionality you would like to see made/added?

Episode 10 - RC Airplane Launcher FAIL! (9 min 1 sec)
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Old Apr 30, 2011, 06:09 AM
Grumpy old git.. Who me?
JetPlaneFlyer's Avatar
Aberdeen
Joined Mar 2006
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What's wrong with the human arm as a launcher for a model like the Easystar?... It would take some improving on in regard to functionality. In terms of 'transportability' the human arm rules, in fact almost everyone carries a pair of them around with them at all times!.. hard to beat IMHO

Steve
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Old Apr 30, 2011, 06:31 AM
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Quote:
Originally Posted by JetPlaneFlyer View Post
What's wrong with the human arm as a launcher for a model like the Easystar?... It would take some improving on in regard to functionality. In terms of 'transportability' the human arm rules, in fact almost everyone carries a pair of them around with them at all times!.. hard to beat IMHO

Steve
You're right, nothing too wrong Now that you say it, maybe I could strap this to my back so its always there for whenever I need to launch an airplane. It'd get some looks at least

In the long term, I wanted to be able to launch something hands free, without the "risk" of ground take offs and without having landing gear. Also wanted to remove the human element from the process.

It was also something that not TONS of people have spent much time on (maybe for good reason ) so I thought it would be valuable for the hobby to explore it a little.

Thank you for the feedback. I still think replacing an arm with this would be interesting. I don't use my left arm as much... maybe it would be a good start.
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Old Apr 30, 2011, 07:33 AM
Da' Cajun
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Lake Charles, Louisiana
Joined Jun 2009
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Quote:
What do you think?
I think it's great that a young feller is out there "thinking" and building stuff instead of playing video games. (I like to play vid games BTW)
And bungee launching is the safest way to get a gearless plane airborne.

However, it seems you are just trying to reinvent the wheel. ...and if you are planning on launching planes heavier than 2(-ish) lbs your wasting your time with a stand alone unit. And lighter planes like the Easystar could probably slide up the rails on it's own power for a beautiful takeoff.

Also, your going to have more problems with the dual, slingshot style bungees than with a mono bungee.
Ditch the pulleys and make some wide (2"-3") rollers with a sleeve/bolt set-up.

Here's a launcher my buddy made for launching EDFs. His bungee was a little weak but the jet took off anyway. But it exposes why a stand alone system is inherently limiting. Bungee length it crucial when launching heavier planes.

jet catapult (1 min 2 sec)
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Old Apr 30, 2011, 08:43 AM
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Originally Posted by Boogie_ View Post
I think it's great that a young feller is out there "thinking" and building stuff instead of playing video games. (I like to play vid games BTW)
And bungee launching is the safest way to get a gearless plane airborne.

However, it seems you are just trying to reinvent the wheel. ...and if you are planning on launching planes heavier than 2(-ish) lbs your wasting your time with a stand alone unit. And lighter planes like the Easystar could probably slide up the rails on it's own power for a beautiful takeoff.

Also, your going to have more problems with the dual, slingshot style bungees than with a mono bungee.
Ditch the pulleys and make some wide (2"-3") rollers with a sleeve/bolt set-up.

Here's a launcher my buddy made for launching EDFs. His bungee was a little weak but the jet took off anyway. But it exposes why a stand alone system is inherently limiting. Bungee length it crucial when launching heavier planes.

http://www.youtube.com/watch?v=g3prsnmhEnM
That is a good launcher, interesting mono rail set up.

I still think I can pull off a heavier airplane launch (>2 lbs) with this set up as it has almost a 10 foot reach, and adding additional tubing wouldn't be too hard (more tubing, more force, but I know, less distance, so a more abrupt launch), but that remains to be seen, it will be a month or two before I build an airplane that weighs that much.

Thanks for the tips, I'm trying to consider how I make the launcher better for next week. Thanks for watching!
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Old Apr 30, 2011, 01:02 PM
Just call me crash for short
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United States, OH, The Plains
Joined Jan 2011
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Shiny. Good try. A bit of redesigning looks to be in order. Give this a thought as a mod for the rail system. Outboard short tubes to hold plane level. once it starts to move forward, they are not really needed. longer tubes close together to keep pieces-parts of the plane away from the surgical tubing. Maybe you have already though of this?

Mark
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Old Apr 30, 2011, 02:08 PM
Ochroma Lagopus Tekton
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Blackstock, South Carolina
Joined Sep 2007
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Question: Has anyone ever tried making a launching carraige? An easy rolling cart that you would set your belly lander on, it would roll along (by the plane's power) carrying your bird until the plane builds up enough speed to take off leaving the carraige on the ground.
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Old Apr 30, 2011, 03:36 PM
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Originally Posted by Quick61 View Post
Shiny. Good try. A bit of redesigning looks to be in order. Give this a thought as a mod for the rail system. Outboard short tubes to hold plane level. once it starts to move forward, they are not really needed. longer tubes close together to keep pieces-parts of the plane away from the surgical tubing. Maybe you have already though of this?

Mark
Shiny? I like that!

I hadn't thought of designing it the way you drew it out, that's pretty interesting. Basically you're separating the functions of "hold the aircraft until its being launched" and "Launch Rail". Not too bad... You wouldn't have the "wobbly" situation as much as there is a straight line for the tubing.
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Old Apr 30, 2011, 03:39 PM
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Originally Posted by Fly Wheel View Post
Question: Has anyone ever tried making a launching carraige? An easy rolling cart that you would set your belly lander on, it would roll along (by the plane's power) carrying your bird until the plane builds up enough speed to take off leaving the carraige on the ground.
Sorry, that would be too easy You're exactly right, basically it would be landing gear (or carriage in this case) that would fall away once you were airborne. Interestingly, Lindbergh considered doing this on the Spirit of St. Louis but decided not to in case he had to land immediately after take off. Not that that means it wouldn't work for us model builders as belly landing doesn't do much if any damage. I think I'll do an episode on this "carriage take off" idea.

Thank you for the idea!
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Old Apr 30, 2011, 03:45 PM
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Quote:
Originally Posted by Fly Wheel View Post
Question: Has anyone ever tried making a launching carraige? An easy rolling cart that you would set your belly lander on, it would roll along (by the plane's power) carrying your bird until the plane builds up enough speed to take off leaving the carraige on the ground.
That idea has been used hundreds of times in both models and full size aircraft (the Me 163 Komet for instance).. It's called a take-off 'Dolly'.

they work fine providing you have a reasonably smooth surface to take off from, much like a regular undercarriage. They would be a good option for EDF jets but the take off run might be quite long without bungee assist.. You could of course use a bungee and a dolly together.
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Last edited by JetPlaneFlyer; Apr 30, 2011 at 04:08 PM.
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Old May 01, 2011, 11:48 AM
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East/Central Florida
Joined Feb 2009
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Just a couple of thoughts
First, You really would never need a launcher for an Easystar - It flys at about 3 mph and will take off from the grass on its own.
The primary use for a launcher is to get a plane like and EDF jet up to speed so you have enough air flowing over the wings to control it. The plane you are trying to launch has too much lift and surface area. Yes I know sailplanes use a launch system, but the planes are entirely different in design, incredabily strong and the system is much more cumbersome.
Try using a jet with your system (read: lawn dart)
Use of a dolly or caunch carriage is only practical with a EDF or top mounted prop plane. However they can work. Four wheel carrage is hard to control. A trike works well with the third wheel in the back as a follower like the front wheel on a grocery cart. It is necessary to have negative camber on the wheels and slight toe in to maintain directional control. Keep trying and keep up the research.
There have been many before you who have tried - Check out the the Wright Brothers pully system using weights. Just another thought for your arsenal of ideas. Good Luck - Keep trying !
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Old May 02, 2011, 09:00 PM
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Originally Posted by MIJohn View Post
Just a couple of thoughts
First, You really would never need a launcher for an Easystar - It flys at about 3 mph and will take off from the grass on its own.
The primary use for a launcher is to get a plane like and EDF jet up to speed so you have enough air flowing over the wings to control it. The plane you are trying to launch has too much lift and surface area. Yes I know sailplanes use a launch system, but the planes are entirely different in design, incredabily strong and the system is much more cumbersome.
Try using a jet with your system (read: lawn dart)
Use of a dolly or caunch carriage is only practical with a EDF or top mounted prop plane. However they can work. Four wheel carrage is hard to control. A trike works well with the third wheel in the back as a follower like the front wheel on a grocery cart. It is necessary to have negative camber on the wheels and slight toe in to maintain directional control. Keep trying and keep up the research.
There have been many before you who have tried - Check out the the Wright Brothers pully system using weights. Just another thought for your arsenal of ideas. Good Luck - Keep trying !
You're right, EZ's don't need it, but thats exactly why I used it

I wanted to prove the concept on something that would easily be successful, so that as I advance to other models I get some good experience on what it can or cannot launch.

I really like the idea of a carriage, that is going to have to happen soon!

Thanks for watching!
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Old May 04, 2011, 10:00 PM
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Canada, ON, Toronto
Joined Nov 2008
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Piston

What about a simple compressed air piston system, kinda like a potato cannon. You could have a set-up like a normal potato cannon (PVC tube, Solenoid) and put a piston in the barrel. The piston would be attached to some sort of launch mechanism and shoot the plane forward when the pressure is released. You probably break the wings on an easy star but it would be perfect for a jet or a flying wing. You could also do some sort magnetic induction gauss cannon but you would need some fairly big magnets.
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Old May 11, 2011, 03:20 PM
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Seattle, Washington, United States, University of Washington
Joined Feb 2003
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Here is a link to a rail launcher with a carriage (launch cart) using springs for the propulsion force. You might be able to scale it down for RC airplane use.

http://www.cmsstudios.com/fly2k/01flights/fhgc.htm
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Old Feb 03, 2014, 04:27 PM
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New Zealand, Wellington, Masterton
Joined Jul 2010
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Carraige Launcher

Quote:
Originally Posted by Fly Wheel View Post
Question: Has anyone ever tried making a launching carraige? An easy rolling cart that you would set your belly lander on, it would roll along (by the plane's power) carrying your bird until the plane builds up enough speed to take off leaving the carraige on the ground.
Yeah, one of the guys at the local RC club has one. Works great.

He made some mods to it and it now has a servo-controlled ( connected to the tx rudder channel ) tailwheel.
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