Most of the time, my interest in model airplanes is focused on the latest and greatest products and trends for radio control aircraft. It seems that there is always some type of new battery, composite building material, or electronic widget to check out. The cutting-edge stuff is all very interesting, but it can also be overwhelming. So, it is often refreshing to examine a simpler, less-technical side of the hobby. I recently checked that box in a big way at an event where I was surrounded by delicate flying models that were covered in tissue paper and powered by rubber bands.
The Flying Aces Club (FAC) is a national organization that promotes events featuring nostalgic free-flight model airplanes. I attended their annual gathering held at the National Warplane Museum in Geneseo, New York. Although I've always been somewhat aware of FAC and free-flight models in general, this was my first exposure to an organized event. It turns out that this event was a great choice for a first-timer. I had an opportunity to see several of the best free-flight modelers in the world doing their thing. There was also the bonus of having several rare full-scale airplanes on display to enjoy.
A Small Slice of the Pie
Free-flight models have no external means of controlling them during flight. Once it has been launched, the trajectory of a free-flight airplane is dependent on how it has been configured by the pilot and the fickle whims of Mother Nature. These machines represent just one small spectrum of the model airplane universe. Yet, there are still countless sub-categories within free-flight.
Thayer Syme is a hobbyist who enjoys many types of model airplanes. His collection includes everything ranging from camera-equipped multi-rotors to giant-scale RC models powered by gasoline engines. Free-flight models are in his collection too. I asked Thayer what he finds most appealing about free-flight.
"I find that you spend so much mental energy flying an RC model that you rarely have time to actually appreciate watching it fly. With free-flight, you put all of your flying energy in before you launch the model. If not properly built and trimmed, it won't fly well. The joy of free-flight is the challenge of setting that model up so that it does fly properly…and then fully enjoying just watching it fly."
FAC focuses on maintaining the designs and techniques that were popular in the early days of aeromodelling. The airplanes are built almost exclusively from balsa wood. In fact, one of the key skills is carefully selecting balsa of an appropriate density for each part of the structure. It's all about achieving the desired blend of weight and strength…a balancing act common to aircraft designers of all types.
There are no factory-built models here. FAC rules dictate that the pilot must also be the builder. Some models are constructed from a kit. Many others begin as nothing more than printed plans and a few sheets of raw wood. Whatever the origin, all of the models that I saw were built with a high degree of craftsmanship.
There are numerous different model categories and competitions that take place at Geneseo. In fact, it takes a week to fit everything in. During the few hours that I attended, I witnessed jet-like models being catapulted vertically into the sky, long-winged gliders that were gently pulled skyward in graceful arcs, and rubber band-powered airplanes that resembled air racers of the 1930's.
Something Old, Something New
While FAC preserves many nostalgic elements of aeromodelling, there are several modern concessions that make things more practical. Most free-flight builders have abandoned slow-drying celluloid-based glues such as Ambroid for modern aliphatic wood glues and cyanoacrylates (CA, aka "super glue"). CA cures almost instantly. This speeds up the building process and is also useful for field repairs.
For the rubber band–powered models, the propulsion systems have changed very little over the decades. Syme mentioned that modern rubber compounds have a bit more energy retention than older formulas, but the overall concepts are the same. What I found interesting was the size of these rubber motors. The simple dime store rubber-powered models that I had as a kid were equipped with a single rubber band about the length of the fuselage. The airplanes that I witnessed at Geneseo often featured several strands of rubber that were many times the length of the model. The pilots used geared hand cranks to wind the motors hundreds of turns. Electronic counters attached to the winding mechanisms kept track of the exact number of revolutions.
Thin tissue paper remains the chosen covering for FAC models. But it is now rare for builders to apply a layer of dope, a lacquer-based coating that bonds, shrinks and seals the tissue. Most modern builders attach tissue to the airframe with glue sticks and apply water or alcohol to shrink it.
Another modern technique adopted by some FAC modelers is to pre-print color schemes and markings on tissue paper before applying it to the model. The tissue is printed on an ink-jet printer. This process permits very detailed graphics to be applied without the extra weight and complexity of decals or painting. The flip side is that it requires familiarity with graphic design software and very precise positioning of the printed tissue on the model.
Whatever finishing method was used, nearly every model I saw was translucent to some degree. Their delicate, hand-crafted structures were still quite visible. It would be pretty tough to hide any sloppy workmanship on any of these ships. I quickly found out that attention to detail also pays dividends after a model is launched.
Up in the Air
Free-flight models are often configured to climb and descend in a circular flight path. The intent is to keep the airplane from drifting too far away during flight. Even so, many participants at Geneseo had scooters, golf carts, or maybe just comfortable shoes in order to chase their flying machines downwind.
Conversations overheard at Geneseo indicate that trimming a model is all about subtleties. The majority of the models I saw spanned less than two feet and were weighed in grams. Miniscule changes could have a significant impact on how a model performed. Pilots talked of shimming a propeller mount by 1/64", or adding a tiny ballast of modeling clay in just the right spot. You might even catch a pilot tweaking their model with a gentle twist on the airframe and a few hot breaths on the structure to lock it in place.
The "jet catapult" gliders seemed especially finicky to trim adjustments. These models look like jets, but have no on-board propulsion system. They are launched by the pilot with an outstretched rubber band. The airplane flies with tremendous acceleration and speed during the launch. It must then transition into a long, steady glide at apogee. That's a large performance margin to account for. A tweak that flattens the glide could also make the jet go spiraling off course during the launch. I also saw instances where even a very slight change to a pilot's launch technique made all the difference between a great flight and a "lawn dart".
Trim and technique are important factors, but weather conditions introduce wild cards that can't be ignored. Tall poles with thin streamers were placed around the field and acted as super-sensitive weather stations. Pilots would monitor these streamers just before launching a model. They watched for specific movements that might indicate a passing thermal. Launching into one of these rising currents of air could have a significant impact on the flight time of their airplane. A strong thermal can carry a model to ever higher altitudes even after the rubber band motor has spent its energy. The thermal might even claim a model for itself, snatching it permanently from sight. Modelers share stories of these "fly aways" with a mixture of sadness and pride.
The Big Picture
Is a free-flight model in my future? Perhaps. I certainly left Geneseo with a new appreciation for the skills that it takes to make a free-flight model perform well. Making a model that flies nicely and looks great is a whole other set of complementary skills. One thing is for sure. I'll be back at Geneseo next year to see more of the fabulous balsa and tissue flying artwork!
Check out Tom Hallman's Youtube channel (maxfliart) for great videos of numerous free-flight models under construction and in flight.
Terry is a freelance writer living in Buffalo, NY. Visit his website at TerryDunn.org and follow him on Twitter and Facebook. You can also hear Terry talk about RC hobbies as one of the hosts of the RC Roundtable podcast.