Radio Control: Sport/Aerobatics
Ron Van Putte
NEW RULES. The biggest news as far as Pattern competition is concerned is the new rules we will be operating under in 1984 and 1985 as a result of the RC Contest Board vote. Surprisingly, the Board voted to add an FAI Master class while retaining an AMA Master class. The new AMA Master class will be based on the 1982–83 FAI Master class. Twelve maneuvers (except takeoff and landing) with a total K Factor of 45 will be selected from the 1982–83 FAI list, plus several new maneuvers. Some K Factors will be changed, but there should be little apparent difference because contests have been using the FAI list lately.
The new FAI Master class maneuvers will include the infamous Turnaround Pattern, which many of us were afraid would be forced on fliers and Contest Directors as the sole Master class. Now, fliers and Contest Directors have an option. Thanks to the NSRCA (National Society of Radio Controlled Aerobatics) proposal which passed, fliers may fly in their respective class: Novice, Sportsman, Advanced, Expert, or Master—plus all may enter the new FAI Turnaround Pattern event at the same contest. This should give the Turnaround Pattern good exposure and provide adequate opportunity for the top Master-class fliers to develop their flying skills and competition aircraft for World-class competition.
I was surprised by the two-class vote because virtually every Master-class pilot I talked to was sure that the single-class proposal would pass. Most pilots didn't like the idea and resigned themselves to what they thought was inevitable. The situation affecting the Master-class proposal might have passed, also permitting Master-class fliers interested in the Turnaround Pattern to back up combined Expert/Master classes, which upset Expert-class pilots. In addition, some fliers thought the Turnaround Pattern would trickle down through classes whether they wanted it to or not. A strongly negative straw vote conducted at the 1983 Nats against a single FAI Master class was enough to convince Board members that adding the new FAI Master class was the better idea.
The rest of the classes will be flying event schedules almost identical to the ones thought to have passed two years ago; changes failed to materialize as a result of mixups in RC Contest Board voting. The Board caught a lot of flak about no change when the 1982–1983 AMA rule book appeared after telling everyone about the new patterns a few months earlier. At this time it looks like the changes will stick. Several rule changes will affect AMA Pattern events.
The most significant one is the elimination of the flight time limit. The pilot must still commence takeoff within three minutes, but will have no time limit after that. (Did I hear a big cheer from Expert-class fliers?)
The option for the pilot to choose the upwind and downwind direction has been eliminated. The pilot must fly the maneuvers in the actual directions listed in the maneuver sequence. So much for those of us who like to perform rolling maneuvers from right to left.
The exclusive right to equal exposure to judges has been eliminated. While Contest Directors are encouraged to provide equal exposure, they are not required to disqualify flights if adverse weather causes unequal exposure. (I presume that Contest Directors will still be required to provide equal exposure if good weather prevails.) While the old rule was applauded by fliers in the past, it does create a hardship for CDs and judges. For the typical two-flight-line contests with 40 contestants, only six rounds are possible. In order to provide equal exposure to judges and to hedge on adverse weather problems, one judging set should be on the line for the first two rounds, another set for the next two rounds, and so on. This means that a set of judges must be on the line for more than six hours at a time and eliminates some judges who can't maintain judging quality for that long. The only viable alternative to this is to have one set of judges for the first and third rounds and another set for the second and fourth rounds. Equal exposure in front of the two sets of judges will be achieved at the end of the fourth round. Then, another set (hardy) judges must be on the line for the last two rounds. However equal exposure is achieved, as a flier, I think it's worth the effort.
One new rule that I have reservations about states that the Contest Director must set the number of flights to be flown before flying begins. The number may be shortened due to adverse weather — but not increased. The rule will limit the CD's options. Unfortunately, it is very seldom that all contestants arrive before the middle of the first round, much less before flying begins. At the beginning of the contest, the CD will be forced to guess how many rounds can be flown. In some cases, the contest will be over on the first day if fewer fliers show up than expected. On the other hand, a surge of late entries could cause a long-running contest.
The new rule that changes the number of flights which count for the final score is a good one because it extends the reward for consistency. Now, as in the past, the best flight is counted if one or two flights are flown, the best two are counted when three flights are flown and the best three are counted when four or five flights are flown. The only change is that the best four flights will count if six or more flights are flown. This will tend to reward fliers who can do several good flights rather than one excellent flight and then poor ones. While this rule slightly favors the consistent flier, I think it's a justifiable change. It will help the people who can put in good early flights and will cut down on having a flier run away with the contest by putting in a couple of "barn-burner" flights.
One interesting rule proposal which passed prohibits the use of rate gyros and autopilots. The rapid development in radio equipment has made it feasible to have preprogrammed Pattern maneuvers. The new rule nips that trend in the bud because rate gyros (or other types of rate- and acceleration-sensing equipment) and autopilots are at the heart of a preprogrammed system. I think this is a good rule because it limits determination of a winner to piloting ability rather than to who has the best sensors, autopilots, and microprocessors.
There are several other changes that are relatively minor. Among these is a rule requiring that the vertical lines of the flight box be aligned with the wind. That should have been standard practice; it formalizes it.
Another rule change moves several maneuvers among the classes and adjusts K-factors on a few maneuvers. The Master-class list has been revised and the Turnaround Pattern included as an optional event. The move toward harmonizing AMA and FAI patterns should help prepare American pilots for international competition.
It would be a good idea for everyone to review the exact wording of all the proposals which passed. Summaries of all proposals are contained in the October and December 1982 issues of Model Aviation. Waiting to receive the new rule book might be a mistake; I always seem to get mine after the first contest.
That's it for now — fly safe and have fun.
One more topic: in the December column I had a picture of the new T2A Mk II which Tom Atkins produces. It has caused several telephone calls already by people interested in how they can get one. I'm not involved with selling T2A Mk II kits, but I am trying to get one myself. In attempting to get a kit, I discovered that there are a lot of people on the waiting list. That sounds like a good situation for Tom, but he won't be able to fill orders as soon as he would like, because he is unsatisfied with the quality of the epoxy-glass fuselages he got from his supplier. He is in the process of getting Dave Scully at Aero Composites to make up the fuselages for him. Knowing the high quality of Dave's work on the Phoenix 8 and EU-1A will make it worth the wait. Tom should be able to start shipping kits to fill the back orders just about the time you read this. So, if you're interested in the T2A Mk II, write to Tom Atkins, c/o Southeastern Air Crafters, 314 Lamplighter Lane, Marietta, GA 30062. You'll get on the waiting list behind me.
The next item concerns a great idea. I got a letter from Bob Skinner (Johannesburg, South Africa), who wrote: "For the past three years I have been trying to collate material related to the Radio Control World Championships with the intention of writing a book. The recent years don't really present any difficulties, but my problem lies with the distant past. You might know that RC/WC was started in 1960 and dominated by American fliers up to 1967 when Phil Kraft became the World Champion."
Bob has attempted to put together a history of RC/WC which will include the official WC emblem, the winner's signature, and details of the winning airplane (including color scheme). He has already collected an enormous amount of information and sent me a partial list of details of the top five finishers in the 13 RC/WC events as well as the seven King of the Beginners Cup events which preceded RC/WC. He needs some items and information which he will describe.
He writes: "At the 1960 RC/WC held in Zurich, Switzerland, Ed Kazmirski became the first World Champion flying his well-known Orion. In 1961 it was able to buy a back-dated issue of MAN with the Orion plans. From the competition reports, I could figure out the colour scheme. No problem, so far. I do, however, require the address of Ed for his signature and the official WC emblem (and colour), if ever there was one."
"I would like to acquire plans for Tom Brett's Peregrine (joint World Champion in 1962). I need to obtain a three-view or a plan of Ralph Brooke's AMANUSA (joint World Champion in 1963). Also, I need Ralph Brooke's signature, colours of his winning model Crusader and the champions emblem from the 1965 RC/WC in Ljungbyhed, Sweden. I need the colours of the WC emblem from the 1967 RC/WC."
"Then comes the sticky part. I have tried to draw up some statistical figures like the winner's percentage of total possible score, the competition average, team performance by country, etc. That's about it. As you can see, it is really a mammoth task, and any support is welcome. Photos, copies, programs, reports, decals, magazines, anything related to the RC/WC will be a great help."
I have several items from the three RC/WC events in the U.S. which I plan to send to Bob. If you have something you'd like to send to him, either mail it to Bob Skinner, c/o P.O. Box 31166, Braamfontein 2017, Johannesburg, Republic of South Africa, or send it to me and I'll see that he gets it. It sounds like a great project and well worth our support.
Ron Van Putte 111 Sleepy Oaks Rd., Fort Walton Beach, FL 32548
Design/Powers
With a flap. Since a wing with a flap is really the same thing as an airfoil having very high camber, the angle for zero lift (which I didn't show) would be shifted over to the left at a negative angle of attack; the curve rises from there, extending above the one for the unflapped section.
Because of Reynolds' Number a model wing can only reach a maximum CL value of about 1.0. Flaps will increase this to about 1.5. On the other hand, a full-size wing can run on up to much higher lift coefficients. Reynolds' No., R = 10,000 × mph × chord in feet. A model with a chord of one foot flying at 50 mph is operating at a Reynolds' No. of 500,000 — indicated by the solid part of the curves — while a full-size airplane will operate at values of R way up into the millions, depending on size and speed. (See "Let's Talk About Reynolds' Number," February 1979 MA.) Suffice it to say that at low Reynolds' Nos. the flow over the wing breaks down readily; the wing stalls at about 12 degrees or so, depending on aspect ratio, wing loading, and other factors.
We can see that, without flaps, Harry will just get a CL of 1.0, and Larry will get 1.5 using flaps. Now, let's check our answers.
- We can find Harry's wing area by using Equation 4:
S = 391 W / (CL V^2) = 391 × 30 / (1.0 × 25 × 25) = 18.76 (say 18) sq. ft.
- Jim's speed can be found by using Equation No. 3:
V = sqrt(391 W / (CL S)) = sqrt(391 × 5 / (0.04 × 3.125)) = 125.06 (say 125) mph.
- Larry's weight from Equation No. 1:
W = CL V^2 S / 391 = 1.5 × 25 × 25 × 6 / 391 = 14.4 lb.
- From Equation 5:
W/S = CL V^2 / 391 = 0.5 × 15 × 15 / 391 = 0.29 lb per sq. ft. (or about 4.6 oz. per sq. ft.)
- If W/S = 0.29 lb/sq. ft. and S = 20 sq. ft., then W = 0.29 × 20 = 5.8 lb.
- V = sqrt(391 W / (CL S)):
- For CL = 0.3, S = 6, W = 10:
V = sqrt(391 × 10 / (0.3 × 6)) = sqrt(2172.2) = 46.6 mph (say 46).
- For CL = 0.6, S = 6, W = 10:
V = sqrt(391 × 10 / (0.6 × 6)) = sqrt(1086.1) = 32.9 mph (say 33).
- For CL = 0.9, S = 6, W = 10:
V = sqrt(391 × 10 / (0.9 × 6)) = sqrt(724) = 26.9 mph (say 27).
Continued on page 138
Transcribed from original scans by AI. Minor OCR errors may remain.
