CONTROL LINE SCALE
Bill Boss, 77-06 269th St., New Hyde Park NY 11040
Featured model: Aeronca Champ 85 (Frank Slavin)
The Aeronca Champ 85 shown this month is the work of Frank Slavin of Philadelphia, Pennsylvania. He is making an attempt at CL flying after an absence of more than 50 years. He noted that he last competed in CL Speed in 1948. It appears that it's never too late to enjoy the sport of model flying. Welcome back, Frank!
His model is a profile derived from a Guillow's kit and is powered with a GWS 400A electric motor turning an EP5043 propeller. The motor-and-propeller combination is powered by seven 350 mAh Ni-Cd cells, resulting in approximately 10 ounces of thrust.
Construction is of balsa with a built-up wing that is covered with 1/32" sheet top and bottom. The front fuselage section is made from 1/4" sheet balsa stiffened with 1/64" plywood to accommodate the motor mounting. The rear fuselage was constructed from 1/4" square members, with the top member laminated to obtain the curvature.
Frank covered the entire model with colored Japanese tissue and finished it with two coats of clear Krylon 1301. He adhered the tissue with a glue stick applied to the wing edges.
The completed model weighs 10.5 ounces and has a wing loading of 17.8 ounces per square foot. The batteries, which weigh 3.5 ounces (heavier than the motor), are rubber-banded to the outside of the fuselage. Frank thought that by doing this he would be balancing the airplane about the longitudinal axis. He added roughly 2 grams of outboard wingtip weight.
Specifications:
- Wingspan: 25 inches
- Wing area: 88 sq. in.
- Dihedral: 0°
- Stabilizer area: 14 sq. in.
- Rudder area: 8.9 sq. in.
- Maximum chord: 3.56 inches
- Aspect ratio: 6.5:1
- CG: 35% chord
- Motor thrust angle: ~2° right thrust, 0° downthrust
- Wing incidence: ~2.5°
Flight characteristics
Frank wrote that the Aeronca had been flown on 40-foot steel and 28-foot Dacron lines, and that it flew well except that the lines tended to slacken when he attempted a loop. He was going to look at increasing the motor right thrust as a possible solution.
Batteries and charging
He charges the batteries at home with a RadioShack AC/DC converter or at the field from the car cigarette lighter through an ammeter. A full charge of the batteries provides roughly three minutes of flight time.
I thank Frank for sharing his experience with an electric-powered profile scale model, and I encourage anyone else who is doing the same thing to let us know about your projects. This kind of model flying is well suited to large school gyms and playgrounds, and it would certainly go a long way toward a solution for the noise problem. It might also be great for some of you who live in country-style settings and have big enough back yards. The quietness of this type of model wouldn't bother your next-door neighbors.
Rules and competition updates
Scale rules changes are a subject for consideration again. During the just-completed rules-change cycle, there were several amendments that will have an impact on CL Scale in one way or another.
CLG-05-1CP1 — Control-line control methods (passed)
Proposal CLG-05-1CP1 has passed and will be published in the new Competition Regulations. It is meant to clarify and limit the allowable methods by which we control CL models. Under the "Control Line General" rules in the 2002–2004 Competition Regulations, section 2 states that the model's elevation control must be accomplished through manipulation only. Recently the question of using radio transmission for controlling CL models' operational features had surfaced and was being experimented with.
Proposal CLG-05-1CP1 changes the last line of "Control Line General" section 2 to read:
"Such manipulation of control surfaces, and any other of the model's operational features, may be accomplished by mechanical means, electrical impulses transmitted through the line(s), or by any other system that does not interfere with the control of any other model or present a safety hazard to competitors or spectators. The use of radio control to accomplish any control function on a control line model is specifically prohibited."
This change not only clarifies the old rule, but it leaves the door open for the possible development and use of new systems that would not have an impact on the safety of other events or forms of modeling. The restriction on the use of radio control in CL models also adds a measure of safety and does away with the possibility of CL interfering with RC activities.
SCA-05-2 — CL Fun Scale event (passed)
The passage of SCA-05-2 creates the CL Fun Scale event, which is an effort to promote/increase CL Scale participation. Bill Reynolds of Caldwell, New Jersey, proposed the event. He noted that many modelers express the desire to compete in some sort of Scale class but do not think their building skills can compete with the more experienced Scale modelers. Bill thinks the introduction of scale ARFs and RTFs in the past several years might provide a solution for the modeler he described. The thrust of this new event is to put the emphasis on flying—not on the building aspects of the model.
Fun Scale is open to modeler-built or factory-built scale models. The rules are the same as for Sport Scale (event 509) except for the static judging. Static scale outline scoring is zero to five points for proving that the model is of a full-scale aircraft that does or did exist. An additional zero to five points may be awarded for proof of the color and markings.
Scoring:
- Static judging: maximum 10 points (0–5 for outline, 0–5 for color/markings)
- Flight score: maximum 100 points
- Official event total: static + flight = maximum 110 points
I have included a copy of the CL Fun Scale scoresheet Part 1 (for static judging) in this month's column. The flight scoresheet—Part 2—is on page 161 of the 2002–2004 Competition Regulations.
SCA-05-12 — Common worksheet proposal (failed)
Proposal SCA-05-12, which was to provide a common worksheet for static-judging the CL and RC Sport Scale events, failed in the final voting.
SCA-05-1 — Pull-test table change (passed)
The pull-test table for CL Scale models, which is on page 157 of the 2002–2004 Competition Regulations, changes with the passage of proposal SCA-05-1. The last line in the table—for models in the 15- to 20-pound category—has been changed from 5G 80-pound maximum to 5G 80-pound minimum.
SCA-05-5 — Profile scale landing gear exemption (passed)
The passage of proposal SCA-05-5 exempts CL profile scale models from having to include retractable landing gear when the prototype had retractable landing gear. This requirement is stated on page 163 of the 2002–2004 Competition Regulations, in paragraph 4.2, item e, of the "Control Line Scale Flight Judging Guide."
Rules-cycle and regulations availability
Be aware that the rules-change cycle has been brought back to two years. Although it is compressed, the cross-proposal phase has been retained. If you want to submit rules-change proposals, get them in early.
Technical Director Steve Kaluf has said that although a printed version of the Competition Regulations will still be available, a decision has been made to make an Internet version available on the AMA's Web site (www.modelaircraft.org). It will be the most up-to-date version because it will include emergency/safety or interpretation changes that might go into effect during the rules-change cycle. Look to the Web version for the final/full wording of all passed proposals.
Please send ideas, notice of upcoming CL Scale events, contest reports, and especially photos of CL Scale activity to me at the address at the top of this column.
MA
Transcribed from original scans by AI. Minor OCR errors may remain.
