Control Line: Speed
By
Glenn Lee 819 Mandrake Drive, Batavia, IL 60510
Mike Couts of Prospect, Ohio set the AMA Jet Speed record of 193 mph last year, and I had a photo of him and his jet model in the last column. His daughter Jennifer was also in the photo with her monoline trainer. Well, this year she is flying serious monoline!
Mike, Jennifer, Bill Nusz, and his wife Gail came all the way from Ohio to Aurora, Illinois to fly Speed at our Treetown Modelaires AAA Memorial Day contest May 29. Jennifer flew her new Class B model to a new junior record of 147-plus mph. It’s a typical Speed model, using a K&B .29 engine with minipipe power, and it has a one-wheel fixed landing gear, a sub-rudder for added stability, and a crankcase-pressurized metal tank.
A week later at the Indianapolis contest she upped the record to more than 150 mph, this time launching from a dolly after removing the fixed landing gear and rudder. She does an excellent job of flying monoline and will probably be flying her dad’s jets soon!
We need more juniors flying Speed, and this is an excellent way to get them started — fly a slow trainer first, then advance to a good, stable, faster model. Why don’t some of you older guys get your grandkids out and teach them to fly? You might even have some fun!
Dollies and Takeoff
Check out the photo of Mark Wood’s dolly. He built a special dolly for his radical FAI-type sidewinder jet. The long, weighted extension counteracts the weight of the lines and the long inboard wing to prevent the model from turning towards the pilot on takeoff. The engine thrust being outboard of the model amplifies the problem.
Vintage Control Line Contest (VCLC)
The Vintage Control Line Contest (VCLC) at Melbourne, Florida this October is really taking off! The organizers are worried that they may not be able to handle all the contestants if everyone who has called or written shows up.
I first mentioned this meet a couple of columns ago, so check back or write Jon Ramsden, 730 Badger Dr. N.E., Palm Bay, FL 32905-5810 for particulars. I’m sure going to try to get there.
How to Start Flying Jets — Mike Couts
I’ve talked a lot about Mike Couts and his jet models. Mike hasn’t been flying them for many years, but he has worked hard, test-flown many models, and is now one of the top competitors in the country. I asked him to write about his methods, ideas, problems, opinions, etc., and he came up with an excellent writeup on how to start flying jets:
One of the most important decisions to be made when planning your new Jet Speed model is picking the type of fuel system to use. Both can be made to start easily, run well, and go fast.
Let’s start with your airplane choice. Pressure fuel systems seem to favor the Hoyt Sidewinder-style plane, and suction systems work excellently on Super Burp upright-type planes. Why? It’s the position of the fuel tank in relation to the engine that makes the difference. During startup, a sidewinder doesn’t have to lift the fuel against gravity to the engine. This helps to richen the mixture during startup.
Remember, a pressure-fueled engine must be metered very lean (.037 to .039 metering jet) and it depends on the pressure to build in the fuel tank before the prime burns out to keep going. Ever see some poor guy run out his entire attempt priming, blowing fireballs? Most of the time this is the problem. Pressure-tap size, fuel-line size and length make a huge difference. Plan on spending a good deal of time experimenting to get it working right. Once the correct setup is found, a start will be had by the third stroke of a good tire pump. Once lit, most planes running pressure will stay running with enough authority to permit takeoff from a rough flying site. Also you’ll have less mixture change from ground to air and the ability to try inlet sizes and shapes not possible on suction feed.
Because pressurized air in the fuel tank will continue to force fuel back into the hot tailpipe and ignite it, put the fire out by just tipping the nose up and letting the burning fuel run out a little. There is no chance of an explosion — you only have a few seconds of fire. (Merle Hoyt showed this trick.)
Now let’s look at the upright model, pure suction feed. Major differences include a true venturi-shaped inlet, flow/jector holes drilled larger and located at the minimum I.D. of the venturi, a much larger metering jet (.055 to .075), and a uniflow-type fuel tank with larger passages that make it much easier to draw fuel. A tire-pump air tank — no priming required. With the correct setup, first-try starts can be the rule. Any pilot standing ready to take a skid launch can really appreciate this. Fire is rare; the engine will stop running if fuel does not flow.
Engine placement with regard to centrifugal feed is critical. Suction is easy to get right on the ground but more difficult in the air. Metering jet selection range is wider and much less critical. I consider the suction system user-friendly and a bit less trouble to tune for good speed.
My advice to the aspiring new jet flier is to try a suction system first, learn and practice the basics of operation and tuning, then try a sidewinder-style plane with one of the new high-performance engines. Both systems are capable of record performance, but both can be made to operate reliably, and both will be fun!
General Comments on Jet Speed
Let me add a few general comments about Jet Speed. Some non-Speed fliers don't know much about jets. When you meet one of these fliers, take a few minutes to explain your jet, then fly it.
Jets are noisy and may intimidate some people, but I find they may be one of the safest powered models. No torque, no vibration to shake things loose, and no props to fly apart or cut fingers.
Speed is flown where it doesn't matter how loud you get. Performance and noise go well together: Been to the racetrack or airshow lately? I can't watch these kind of events on TV with the sound turned off, can you? If your answer is “no,” you'll like Jet Speed!
I enjoy Jet Speed and will continue to do so. It's fun to experiment and see results without any other changes. With jets, more power equals more mph — period. You won't have to find the right prop pitch to complement that new pipe, etc.
In my few years of Speed flying I have observed many times that the best equipment doesn't always win. That slot was often filled by the well-tested person who could always use his machine to its full potential. Remember this old adage: "Beware the man who has only one gun — he probably shoots it well!"
Transcribed from original scans by AI. Minor OCR errors may remain.
