Indoor FF 2023 Event Season

Indoor Free Flight

By Don Slusarczyk | [email protected]

As seen in the September issue of Model Aviation.

THE INDOOR Free Flight (FF) season in the Midwest has been fun for me throughout the last few months. It started off with the Jim Richmond Open (JRO) in West Baden, Indiana, at the beginning of April.

This was the first year that the competition was three days long instead of only two. The attendance was good, with 27 entrants. Because of my work schedule, I had to drive down Saturday morning instead of the night before, so I missed part of Saturday’s flying; however, Sunday and Monday ended up having better flying conditions, so I lucked out!

The flightline at the Kent State Indoor FF contest. Two new AMA records were set.

There were two new Category III national records set at the JRO. The first was Ray Harlan with his electric FF model. Ray put in a flight time of 33:19 with his biplane design. For those who are unfamiliar with the Indoor Electric FF rules, models are powered by a single 10 mAh LiPo battery. Ray’s model also features a geared reduction drive, carbon-fiber propeller blades, and a manually adjustable blade pitch.

The other Category III national record was set by Hamish Christie in A-6. He put in a flight of 10:12 with his tandem A-6 design. Tandem A-6 designs are becoming popular. In fact, all of the A-6 models flown at the JRO this year were tandems. Hamish’s design is unique because it has a "stinger" tail extension. This tailboom extension allows ballast to be added to get the center of gravity as far back as possible. Also worth noting is that his record was set using the current Tan Super Sport rubber.

After returning home from West Baden, it was only three weeks later that the two-day Kent State Indoor FF contest was held in Kent, Ohio, at the Kent State University Field House. This year was the first time that the competition had occurred at the site for several years because of COVID restrictions. There were 25 registered contestants this year, and the air was excellent for both days, despite the cool outdoor temperatures and the hard rain that fell.

Hamish Christie is smiling because he just did 6:09 with his Phantom Flash. He later set a new AMA record in A-6.

Ray Harlan’s Indoor Electric FF model after a new AMA national record of 33:19 was set.

The German Café has become a longtime tradition for those who fly at the JRO in West Baden IN. This year was no exception.

There were two new Category II national records set during the weekend. Ray put in a flight of 24:14 in Indoor Electric FF with the same model he set a record with a few weeks earlier at West Baden. Josh Finn set the Unlimited Catapult Glider record with his Cat’s Meow design. He put up 73.4-second and 72.4-second flights for a two-flight total of 145.8 seconds.

Josh sells a Cat’s Meow kit and also has a build video on the J&H Aerospace website, so if you are interested, check it out. The link is in "Sources."

Josh Finn’s Cat’s Meow Unlimited Catapult Glider set a new AMA national record.

Check the tip on all A-6 propellers to make sure the blade does not exceed the 6-inch diameter restriction.

Measuring Propeller Diameter

One rules issue did come up this year at the JRO regarding how propeller diameter is measured. A-6 and Limited Pennyplane have propeller diameter restrictions. Depending on the shape of your propeller blade, it is possible for a propeller to be oversized if it has a wide, straight cutoff at the tip.

An A-6 propeller, for example, has a 6-inch maximum diameter. This means that the propeller would have to fit into a 6-inch diameter cylinder. Quite often, we only measure along the spar to check the diameter, but a heavily flaring propeller blade with a straight cutoff tip can have the corner of the propeller extending beyond the 6-inch diameter maximum.

This is exactly what happened at West Baden. An A-6 set the record with a wide, flaring propeller blade. The corners of the blade, however, extended past the 6-inch diameter limit, so the flight was disqualified.

When I started flying A-6, I began checking this condition on my propellers after they were completed and I sanded away any blade sections that extended too far. The way I check this is by using my propeller pitch gauge. I remove the protractor section from the gauge then use a piece of 90° aluminum and clamp it to my pitch gauge just below the radius specified by the rules.

For A-6, I use a digital caliper and set the aluminum stop to 2.99 inches. I then rotate the propeller blade back and forth at the propeller shaft to make sure the propeller clears. If any part of the propeller tip touches the aluminum stop, I sand it away. The same method can be done for Limited Pennyplane. Just set the stop slightly below the allowable 6-inch radius.

Ray has put together a nice article on this topic, including a template that can be printed for A-6, as well as how to make a special measuring fixture for A-6 and Limited Pennyplane. His article, "Designing Props Having Diameter Constraints," is available on the Indoor News and Views website.

Until next time, keep the weights down and the times up!