Control Line Scale-2011/08

Author: Bill Boss

Edition: Model Aviation - 2011/08
Page Numbers: 138,139

Rules Change Proposal CLS 11-9

During the past few months I have received a number of emails concerning two major control-line (CL) rules proposals. Proposal CLS 11-9 tries to define what happens to the wingspan and tail-assembly span when building a profile model. The other proposal concerns using the 2.4 GHz radio system in CL models.

Profile Model Scale Issues

The CLS 11-9 proposal adds a new Paragraph 2 to the Control Line Profile event 521 under Model Requirements. This new paragraph is headed "Design and Static Judging Guidelines," and attempts to provide guidelines in Profile Scale concerning what to do with the section of wing or stabilizer that would normally be within the body of a full-fuselage airplane when building a profile model.

During the course of a number of email messages from various modelers, the proposal brought to light several problems. The proposal attempts to keep all aspects of the profile model scale, and if the wingspan or stabilizer span is not kept to scale size, the model would be subject to loss of points when being judged in competition.

A Corsair sketch (described by correspondents) illustrates some of the problems you might encounter when trying to comply with this new rule. Lines A and B represent the wing size and shape with a full-bodied fuselage. Lines B and C represent the wing extension necessary when building a profile model and keeping the wingspan scale. Note the thickness of the wing extension to the profile fuselage. The added wing thickness on the profile fuselage could be considered out of scale and would be a reason to deduct points in judging. On the other hand, if the wing thickness of lines A and B is kept, there is a decrease in the wingspan and it brings the landing gear closer together. Again, this is a possible loss of points.

Clark Macomber of Chicago, Illinois, summed it up well when he wrote, "Without any compensating pluses, 'Paragraph 2' effectively eliminates a large proportion of potential subjects from consideration for Profile Scale. Corsairs, Stukas, B-25s, and other subjects with polyhedral cannot meet the new rule requirements unless unsightly and almost certainly score-diminishing changes in the wing-root location or dihedral are made."

One of the things we must remember is that a profile model can never be truly scale simply because of the profile fuselage. It would be almost impossible to emulate the structure of the full-bodied fuselage in a profile airplane’s fuselage, which can vary from 1/2 inch to 1 inch thick. Being overly technical concerning scale sizes and shapes in the profile events defeats the purpose of why these events were established. The original intent was to encourage those who might have the slightest interest in scale to try their hand at something new.

A judge at 15 feet from the subject cannot determine if the wingspan or other features of a profile model are as scale as the three-views presented. Judges no longer use the ruler. Macomber also noted that "a decent judge can, however, evaluate how well the character of the subject has been retained, and that's what the rules should be asking him to do." Based on the various emails received and the uncertainty of how "Paragraph 2" could be applied, I believe it is best if the rules proposal is defeated.

2.4 GHz Radio Systems in CL Models

The 2.4 GHz question has generated emails from CL modelers who have been using the system without any problems and are in favor of passing the proposal. Submitted by Don Burke from California, a change to CL General Rule, Paragraph 2 replaces the last sentence with: "The use of 2.4 GHz radio systems to accomplish functions other than providing aerodynamic control of the model's elevation on control line models is allowed."

Mark Vicente of Houston, Texas, has been using the 2.4 GHz system in electric-powered models and notes that it lends itself to the simplicity of "plug-and-play" for speed control and servo functions, making it easier to provide mechanical operations in CL models.

Joe Eiben of Towson, Maryland, wrote the following:

"As a lifelong CL scale flyer (50 years and 1976 Nats winner), I have sadly watched the decline in participants and quality of models in all categories of this AMA control line event. Although there are several reasons, one has always been an ongoing issue: the difficulty of operating mechanical functions.

"Granted, there now exists more than one electronic system that will allow features such as raising and lowering flaps and/or landing gear and the like by sending a signal through insulated lines. I have personal experience with these systems, and their installation and operation is somewhat involved and not entirely reliable.

"As a result they are not widely employed and one simply needs to travel to a CL Scale meet to observe the number of models flying that compete without operating features the full-scale aircraft employs, but the model does not. Unfortunately, this has come to be accepted in the CL community and, in my opinion, detracts from the flight of a fine scale model.

"AMA has primarily cited interference issues for not allowing mechanical features to be operated via radio on a CL model. With the advent of 2.4 GHz technology, I believe it is time to delete the AMA directive to not allow the use of RC in CL models.

"The net result for CL Scale, in my opinion, will be scale model airplanes performing on par with their full-scale subjects and an influx of new scale fliers who can look forward to flying models with an easy method of operating a multitude of functions — a major leap from just throttle control. I strongly urge you to support this rule change."

Avro Lancaster (Photos by Gerald Boyd)

This month's photos of the Avro Lancaster are from Canada's Gerald Boyd. He designed and scratch-built the semiscale model from his plan drawings. The wingspan is 50-3/4 inches, fuselage length is 34 inches, weight is 45 ounces, and four Cox .049 engines provide the power.

Its color scheme is taken from the Avro Lancaster B II bomber DS626 KO-J, 115 Squadron, from East Wretham, March 1943. Scale details are taken from Sam Publications' Modelers Data File: The Avro Lancaster, by Richard Franks.

The dark green and medium brown used in the camouflage scheme are brushed on Humbrol enamel, and finished with a clear H.D. Design spray. Panel lines were made using black industrial Sharpies.

The Avro Lancaster was the Royal Air Force's most strategic bomber. The successor to the Short Stirling and Handley Page Halifax, it became British Bomber Command's most valuable airplane.

In addition to many missions, the Lancaster took part in sinking the Tirpitz in a Norwegian fjord in November 1944, and in the destruction of the Möhne, Eder, and Sorpe dams in the Ruhr Valley.

Full-size Lancaster specifications:

Wingspan: 102 feet
Height: 20 feet
Length: 69 feet 6 inches
Weight: 70,000 pounds
Engines: Four Rolls-Royce Merlin 12-cylinder V liquid-cooled engines
Armament: 10 machine guns
Bomb load: 22,000 pounds
Speed: 287 mph at 11,500 feet
Service ceiling: 24,500 feet

Contest Notice: Cholla Choppers Fifth Annual 1/2A Multi-Engine Profile Scale

The Cholla Choppers of Tucson, Arizona, will be hosting their Fifth Annual 1/2A Multi-Engine Profile Scale contest on Saturday and Sunday, October 8–9, 2011, at Christopher Columbus Park.

Two categories will be flown: Limited and Unlimited.
Limited: models with pitch control only. No throttles or other functions controlled by timers, electronics, or other means will be allowed.
Unlimited: throttle-equipped models having any number of functional ground or flight features. Any glow or diesel engine not exceeding .061 is allowed. Exception: the OK Cub .074 may be used.
Scale judging: Saturday starting at 9 a.m.
Official flights: Sunday starting at 9 a.m.

This contest has become popular and participation has increased in the past couple of years. It is a low-key event where contestants help each other and enjoy a great day of model flying. For any questions and full details about the contest see the "Sources" listing.