Letters to the Editor
All letters will be carefully considered; those of general interest will be used. Send to Model Aviation, 1810 Samuel Morse Dr., Reston, VA 22090.
Mr. Mulligan Plus
After looking at the Mr. Mulligan in a recent issue of MA, I decided to send in my version. I call it the Mulligan Plus.
Three years ago I decided on Mr. Mulligan for a Quarter Scale project. Wanting both a monoplane and a biplane presented a special financial problem, but my Mr. Mulligan could be the solution.
I was told that I had picked the ugliest plane in the world to build, so you can imagine the remarks I heard when I appeared at the monthly club meeting with the nearly completed skeleton of Mr. Mulligan dressed as a biplane. “Wow, but it will never fly, too big and too heavy, twice as ugly,” etc., were things I heard.
I flew it for two years as the Mr. Mulligan monoplane. Then one Sunday afternoon last fall I decided I had flown Mr. Mulligan long enough. Besides, everyone wanted to see a spectacular crash. On went the lower wing.
Being quite nervous as to how the biplane version would handle after all the comments, and beginning to have some doubts myself, it was decided that Ray Perry, the club's flight instructor, would make the first flight. As everyone gathered to witness the event (crash?), it lifted off beautifully and climbed out without so much as a trim change into beautiful hands-off level flight.
By using the original plans and eliminating the first two ribs, the lower wing is 10 in. shorter. Quarter-inch dowels in the wing root slide into plywood boxes built into the landing gear plate. The dowels are secured with screws.
The plane is powered by a Quadra. It's covered with Super Coverite and spray-painted with Krylon enamel. The wheel pants have been removed for flying on the grass.
It is big and heavy (about 24 lb.), but the Quadra is sufficient for loops, aileron rolls, and a mean snap-roll. A 20-6 prop seems to be best suited for this combination.
Arthur P. Nagelin Bangor, ME
Mr. Mulligan ugly? Wash out your mouth with soap! The picture shows that it has character as a bipe, too.
"Single" Twin
Thought that you would like to see the latest from FFF (Fickle Finger of Fate) Aviation—a single-engine twin. It was inspired by the really great article in the July 1983 issue. (Editor: That would be Frank Baker's DH 98 Mosquito for two .10s.)
I bought a House of Balsa Shoestring and sorta cut and refitted until I wound up with the plane shown in the picture.
Actually, I love this kind of building. There is nothing in this plane that is exactly like the kit except for the inner wing ribs and the spar design. It uses a fiberglass arrow shaft spar (actually, two arrow shafts). The engine nacelles are urethane foam (solid) with the noses holding whatever weight was necessary to get the CG where I wanted it. Total weight with a Max .15 and three-channel equipment is 3 lb. on the button.
At the time of writing it hadn't been flown, but by the time you are reading this it will either be a veteran of the sky or a victim of the ground.
The fellow holding the plane in the picture looks remarkably like me, except that I seldom can be caught with a tie. My daughter, who soloed on the Minolta for this one, must have a quick trigger finger to capture such an event. The other, better-looking picture is the same plane but with the above-mentioned daughter holding it. The engine detail shows better here. Why is it that nobody ever feels that they are old enough to have a teenage daughter?
Tom Chipley Designer/Test Pilot, FFF Aviation Rocky Mount, NC
Frequency Control Idea
After reading many articles on frequency control and seeing a few models "shot down" at my local flying club, I have come to the conclusion that there has to be a better method—one that will eliminate human error.
I have an idea which might be worth stating, even though it would be a little costly. Here it is.
Build a small receiver into the transmitter which is activated by the power switch. When the unit is turned on, the receiver scans the frequency zone and does not allow the transmission of a signal until the frequency is clear.
Also, the same unit could be made to sound an alarm if an interfering signal is received before the end of the flight, possibly allowing enough time to prevent the loss of the aircraft.
If radio manufacturers would design and market a system of this nature, I think many would benefit from its use, and I (for one) would not mind the additional cost, as it would pay for itself with the first use.
Ron Fiedler Temecula, CA
We passed on the above letter to our Radio Technique contributing editor (and chairman of the AMA Frequency Committee), George M. Myers. His response to Ron Fiedler's letter follows.
Response from George M. Myers
I, too, think that the idea of having a monitor built into the transmitter is a good one. If you will check "Radio Technique" in Model Aviation, June 1982 (page 92) and August 1982 (page 28), you will see some suggestions similar to yours.
As I see it, the monitor only has to check the channel that its system plans to use (assuming a crystal-controlled transmitter). Scanning the other channels really isn't necessary.
As for implementation, the simplest approach would be to build a crystal-controlled receiver into the transmitter. In that case, add a transfer switch that can attach either the transmitter output stage or the receiver input stage to the antenna. For safety, the transfer switch might also disconnect the power input to the transmitter output stage (module, RF board, or whatever) while supplying power to the receiver. Thus, only one unit would be able to operate at any given time. You could do this right now, with the tools available to any modeler.
Your second request, asking that the monitor also sound an alarm when an interfering signal appears, is a bit more difficult to satisfy. We only want to know what interference is received at the airplane's position. Thus, the proper solution is to have the airplane notify you of its problem. The Servo-Gard is a device available (check the ads) which inserts between your throttle servo and your receiver. It cuts back the engine when interference is received (or when battery pack voltage drops below a preset level). Depending on the situation, you either glide down at idle power, or you crash with the engine turning slowly.
Putting the sensor at the transmitter (as you requested) introduces the problem of finding a very weak signal (interference) hiding under a very strong one (your transmission). Since we are presuming that the two signals have similar properties and identical frequencies, we know that the problem of discrimination is technically difficult (read: expensive). Thus, it is unlikely that such a device will appear.
Your suggestions are appreciated. Please keep sending them.
George M. Myers Hicksville, NY
Do keep in mind that you can learn a lot about the possibility of interference—particularly the presence of someone else on your channel—simply by turning on your receiver before a flight and watching and listening. And if any interference is noted in flight, resulting in some unwanted control input, by all means immediately throttle back, if that's possible, and land as quickly as you can.
Transcribed from original scans by AI. Minor OCR errors may remain.
