July 8, 2025: Control Line Scale

By Fred Cronenwett

There are multiple Control Line (CL) events at the Nationals. They all share a bellcrank to control the elevator and fly in a circular pattern. But each CL event is very different in its purpose. The goal in a CL Scale event is to build a smaller version of a full-size aircraft in appearance and flight qualities. Pilots in this event have to know the historical information about the full-size airplane and show that information to the judges during static judging. The documentation package that the judges use to decide how close the model matches the full-size aircraft includes a 3-view, color information and photographs.

You will see a variety of models being flown, but all of them are based upon a full-size aircraft that has flown before. During static judging, the models are graded for the accuracy of the outline of the model, colors, and markings. In the Sport Scale class, the static points represent half of our total point score. So you can’t make changes to the overall outline, color, or markings without losing points.

In Sport Scale, there are a total of 200 points that can be earned with the static and the flying criteria. The first 100 points are with the static judging and the next 100 points are with the flying points. Realism is a big thing when the model is being flown. If you are flying a Piper Cub in Sport Scale, the model needs to flown like a Cub (slow) and not like a warbird (fast).

There is a variety of CL Scale events being flown, including the smaller 1/2A-powered models, which do not have any throttle control. All of the other events are typically flown with throttle control. You can fly without throttle control, but the flight score will suffer if the model is flown that way. If you see a pilot flying with an RC transmitter, that is because 2.4 GHz is allowed to be used in CL Scale for the throttle and other features. However, the elevator must be controlled by the bellcrank.

Because we are allowed to use 2.4 GHz radio control equipment, you will see electric power, retractable landing gear, flaps, and other features that were difficult to operate when using the older mechanical 3-line controls. CL Scale can use model designs and other items that were originally designed to be used with an RC model. The CL Scale model with 2.4 GHz controls is essentially a RC model with a bellcrank installed to fly as a CL model.

The models being judged on Thursday, July 11th are the F4B models being considered for the 2026 F4B Scale team that will travel to the UK for the World Championships in 2026. Our contest director, Peter Bauer, took 1st place at the 2024 F4B world Championships. The flying portion for the F4B event will be flown on Sunday afternoon, July 14th and then again on Monday, July 15th.

The AMA has rules for 1/2A, Fun, Profile, Sport, Team, and Authentic CL Scale, but these rules only apply to CL Scale events held in the USA. The international rules are the F4B rules, which are similar to the AMA Sport Scale rules with some minor differences.

The static judging for AMA events will be done at Site 6 on Friday June 12th and then the first round of flying will be done later that afternoon. So come out to Site 6 on Friday to see the AMA events during static judging, and then flying later that afternoon.

Just for a little bit of fun, does anyone recognize the flying site called Area 34, and where it might be located? I have had the pleasure of flying at this location several times. If you know where this is located let everyone else make their best guess!