C/L Fan Jets?

Has this happened ... yet?

You mean ducted fans and turbines? Sure.. a guy called Charlie Bauer shows up at the Nats every year with such contraptions as a F-86 Sabre or a 8 foot wingspan U-2 (lines are only 60 feet, mind you...).

Probably the most dangerous act that I have witnessed in C/L

See Ya

Peabody

Really?

I never did get to see the U2 fly, but why was it dangerous? The ducted fan F-86 could barely get off the ground flown off grass. Probably better on asphalt.

>Probably the most dangerous act that I have witnessed in C/L
>
>See Ya
>
>Peabody
>
>www.gscb.us / www.richpeabody.com

So you never saw a dyna jet scale job fly with an aluminum and asbestos liner. You want to talk about getting to that model fast and opening the hatch and blowing cool air through it.
Yes it was a turbine your talking about and while I've never seen the model you talk about it probably was a small one and certainly had a govenor on it to hold it back. If propane powered well if he crashed it could have been noisy and spectacular but so is any model on fire and I've seen a few of those.
Dennis

I have seen Charley's U-2 Fly several times, but it did not seem dangerous to me. The model takes of flies the require ten laps of level flight and then he throttles down and lands it. It also flies on seventy foot lines.

Leroy

>Has this happened ... yet?

Yes.

There have been any number of ducted fan applications over the years for Free Flight and Control Line that date back to the mid 1950's. Performance was marginal at best. Some serious work was done by a P.E. Norman in England during the 50's and published in Aeromodeller. Most of his work was for free flight.

But one of the first serious and successful Control Line application for a ducted fan that I am aware of was done by Mike Kulczyk in the mid 1960's. As far as I know, this precedes most of the work that led to the fairly successful ducted fans that have been used in RC since the 70's. Mike published his work in February 1971 issue of American Aircraft Modeler. This was a summary of his work and showed models that I had seen in 1967. Mike entered that model in a North American Scale Flight Masters contest at that time. Its performance was impressive. He had a scale F-100 that performed well with the fan that he developed. He perfected the "cannister" concept that enclosed the engine and fuel tank and provided a shroud for the fan with flow straighteners. A derivative of that fan design was made by a friend of his that was mounted in a suburb Control Line scale Desault Mirage that I had the priveledge to fly in 1969.

Mike had several CL scale jets in that period, including a U-2, an Me-252, his own Mirage among others.

Mike has not received much, if any, attention or credit for his work. I may be taken to task on this, but his work preceded the work that Dave Platt did in getting a succussful fan operating in an F4D Skyray which was one of the first fan jets to be flown in RC scale at the Nats. Dave took some of the ideas from Mike and improved the performance of the fan by different blade shapes and inlet design. Then came the developments by Larry Wolf of Jet Hanger and Bob Violet of BVM Models which put fans firmly on the RC scene. Bob Kress also had some significant developments and had several packages on the market from time to time. But these all apeared after Kulczyk's work in the 60's and published in 1971.

Now, small turbines are available. One of the smallest commercially available turbines is not much larger than a soft drink can, weighs about 15 ounces and has about 7 1/2 pounds of thrust and is completely conatrollable.

LAST EDITED ON Oct-02-06 AT 08:02 AM (CST)
 
Here's one. I do not know who had it. Once, in the late 1980's, me and my boy went up to Brodak's to fly. Several fine gentlemen, Mr. Brodak and others, were there and I must say, we were impressed with the planes. This is the only CL fan model I think I've ever seen. It was an older fellow who had it, but his name I'm afraid I long ago forgot. Time and work constraints prevented us from returning, seemed like we could never find the time to fly then, so we never got to see those guys and planes again.

If your question is really about stunt planes, I doubt it.

My understanding (or misunderstanding) is that fans work best as the velocity of the airflow over the aircraft approaches the velocity of the airflow exiting the duct.

This affect can be observed by the steady (slower) accelleration of a fan jet or turbine. Probably not too good in the corners.

IMHO, scale=yes, stunt=no. But that's just an opinion.

I know someone that flies a Dyna Jet Pulse jet engine airplane on 90 ft Control Lines in his back yard.

LAST EDITED ON Oct-02-06 AT 09:59 AM (CST)
 
Control Line jets, just like real ones, have no prop wash over the flippers and must, therefore, develope a lot of airspeed to just to rotate the nose off the ground.

I used to "crew" for a man who frequently flew a DynaJet-powered F-92 out at Rouge. As mentioned above, it needed lots of airspeed, like about two laps worth. The post flight drill included chasing down the plane, opening the hatch and pumping air to cool the jet.

It took a 4-man crew to fly: pilot, holder, pumper, and battery man. I understand that the battery man has been automated out of a job. Now they put a stinger up ther tail.

I saw a jet speed job graze the concrete at the '65 State Meet and make a 20-foot fireball. No problem, everybody was a lot more than 20 feet back. Unlike electics and muffled glow engines, nobody walks into a DynaJet circle.
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I can't imagine that there would be a problem with a piston-powered ducted fan.
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I took a long inside look at some true jet RC models at the Chatham Nats. They look pretty-well developed, and a lot quieter that I imagined.
Downside: with all the required equipment, it would make for a very big, heavy, and powerful CL model. Basically, an anti-tank missle on wires.