I was just wondering if anyone had ever seen of a launching system for model jets similar to that on an aircraft carrier? I think that would be a cool thing to have.

I have not seen one but am seriously considering it for my planned F14 Tomcat.

My field is limited in space so this would be great, arrestor hook as well.

I dreamt of this for a long time.
Actually I tried using 2 sandbags attached to a rope years ago but my landing at that time, well never came close :stupid:

C Lim
Smooth Landing

What about a highstart like used for launching sailplanes? It would be a two person operation.

Person 1: Hold the jet at end of runway.

Person 2: Streach the highstart and hook it up to the launch hook on the bottom of the jet.

Person 2 (pilot): Throttle-up and give the signal

Person 1: Release

The heavy duty highstarts lannch some fairly heavy sailplanes to up around 500' and all the jet would need is takeoff speed!

It would would be great for anyone to post thier design ideas for one of these. I think I am going to design and try to get a prototype built over the next few weeks.

OK... I couldn't resist... The temtation was just too great...

Tim

You can create all the head wind you want for a good launch this way and still listen to your favorite radio station at the same time.

I got an Ideal in my head for a Cat launch i want to build for my
F-14s also, similar to the full scale catapult but instead of using steam, use a nitrogen tank with 3500 PSI to launch it on a rail shuttle system in 1/10 scale. All i need is to find the time to build it, retirement is coming though.
Taking orders now! LOL.

Do you guys think that the 120 psi that you get from an air compressor would be enough power to move a 20 pound model with a towbar?

One more thing. About how many feet of runway should i expect to use with a system that operates very similarly to the real thing?

Curious

Would this system use the landing gear up to take off or down as in the real thing. I was also wondering if the catapult would also be built for landing. I mean if we're going to go Navy, by all means let's go all the way! Still, it would be nice.

edmcman, if i remember right the launch deck is around 300'.
I don't think an air tank with 120 PSI would be enough pressure and you would need a really big air tank to have enough volume for a launch. I had planned to use the small nitrogen bottle 3500 psi with a regulator to adjust to the right pressure and stage it about 3 times with solenoid valves (so i wouldn't yank the nose gear right out the airframe.) I was going to make a mock-up of the F-14 with the same nose gear shuttle like in the model aircraft with the same weight of it to get a starting point.Then do some test to see what it would take to get the right speed for a quick safe launch. 0 to a hundred in about 3 or 4 seconds!

Tamecat, Landing is not a problem with the F-14 and most heavy ducted fan aircraft, Its getting the beast in the air quickly and safely, The fans have plenty of power/speed when its in the air and gets up to speed, but its needs that kick in the butt to get it there a lot faster and safely without a long slow shallow climb. But the turbines should do that a lot better, but i still think about the Cat launch and want to do it when i get the time.

Skybouncer

What I meant was, would the catapult be large enough for takeoff and landing. When I hear people talk about a catapult system, this is what comes to mind. A large structure to launch and recover the plane in limited space. I think that would be great! I fly off a mountain side. When you land, there can be no room for error otherwise you end up hitting the side of the mountain (Don't ask how I know!), or Running off the side of the mountain (again, don't ask). It would be great if someone designed a system that could get the plane in the air, without ripping off the nose gear, safely. I say go for it and the rest will follow!

Tamecat I'm sure its possible to land on the same deck you cat lanuch from but the odds of it are like that mountain top your speaking of just a lot smaller. You would have to reinforce your airframe a lot more to keep from ripping the rear of your plane off when you grab an arresting wire. Some of the load could be transfered to a shock cord, but i don't think it would be worth risking a 6000.00 aircraft on to attempt it, odds aren't good at hitting a 4'x32' wide deck every-time. This could be done safely with a slower prop plane I'm sure but not a fast moving heavy jet.
The Cat launch i have planned would be made from 4 sheets of ply (32')with the shuttle built to it and hinged so all 4 sheets would fold and would have small wheels and a handle to make it easy to transport, just roll it in or out of the trailer, unfold it and you ready to launch. I would set it up alone side the runway for launching when it would be out of the way and land normally on the runway.

With almost 1000 full scale carrier takeoffs and landings I can tell you a few things that I have observed and how they would apply to models since I am a lifetime modeler as well.
Modern catapults are about 300 feet long and are steam powered. The forces on the full scale(FS) planes are unbelievable! At the next airshow go and look at the difference between the service aircrafts landing gear. The Tomcat gear has a draw bar on the nose gear and the shuttle will pass between the nose wheel tires. The drag link on the back of the nose gear is the major load carrying part of the nose gear assembly. I don't think this system is easily replicated in a model and I would shun away from 3500psi. The volume of high pressure air required would be a large bomb without the proper safety proticalls.
I would suggest the high start method of launching with attach points on the bottom of the airplane. Maybe a dolly on a track to sit in so that the landing gear doesn't catch in the high start. This could be set up to accelerate to take off speed and then the plane would takeoff under its own power or another system were the plane would be pulled into flight more like a glider set up.

For landings a tail hook that is scale would be very difficult to make strong enough. I have alot of experience with prop planes and arrested landings and I would suggest you trying that for a while.
The weighted bags and string works ok. It would be best to plan to land prior to the wire and roll into it for a model jet set up. one problem would again be the wheels catching in the arresting gear.
You could use the Barrier setup like the Air Force does full scale. It is in the overrun and about 2 feet high and if the plane gets that far it will bring it to a safe stop although some damage to the plane may occoure.
In the models it is like having progressivlly taller grass at the end of the runway.
If you have any further questions you can email me on or off line
Sparky

Probably have a pretty hard time finding a model jet with the structural strengt to withstand the energy needed for something like a cat shot or trap.

how can you get the runway to move like a carrier?

Or does the controller stand atop of a contraption where his buddies rock him around so that he "thinks" he's on a carrier deck?

On a serious note though, the folks out a Nellis AFB NV (at least when I saw them last in 1990) had a compressed-air catapult for the Mig27 (or was it a Mig29...can't remember) rear prop RC plane they had that was used for the aerial gunnery course. Not quite sure how it was all arranged, I was to busy shooting at the time :P I do remember that the aircraft had about a 48" wingspan

I have launched jets from the ground using a hi start on short runways several times, and it works well .....

I tried to set up a rocket assisted take off on an old T38 I had (R.I.P.), and it looked cool, but was not too efextive, i think the 4 d sized rocket engines were not enough ...



Wojtek

If you need any ideas. I have some videos of something nasa wa tring with model airplanes to use with rockets

http://www.traderc.com/rockets/ Jato assisted take off about half way down the page