Flight
2013World Free
The world’s best freeflight modelers come together to crown the World Champion!
By David Beales & Martin Dilly PHOTOGRAPHY: MARTIN DILLY T
he 2013 World Free Flight Champi- onships were held August 3–10 at Moncontour in France. This was the biggest model flying Champi- onships ever, with teams from 40 nations competing in the F1A glider class, F1B for rubber-powered Wakefields and F1C for en- gine-assisted gliders. More Asian nations took part, including both North and South Korea, Mongolia (venue for the 2015 World Championships) and Indonesia, as well as Japan and China. The Championships were also one of the most successful for the Unit- ed States, but more of that later. For US F1B team member Walt Ghio his problems started before the contest when he arrived in Paris to find that his model box wasn’t on the aircraft and seemed to be lost without trace. He then flew back to Califor- nia to collect a second box of models, only to find on getting back to France that the orig- inal box had arrived.
There were problems for the Champi- onships organizers too; after a very late and wet Spring in Europe the crops were about three weeks late and instead of acres of flat maize and sunflower stubble the flying site was surrounded by fields of yellow sunflow- ers. Bad news for model retrievers; howev- er, the local farmers worked through the
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night and enough was harvested for the contest to start.
The dynamo behind the 2013 Champi- onships was Myriam Morandini, who flies F1B Wakefields herself, and the small vil- lage of Moncontour, with a 12th century castle looming over it, collaborated, with models and posters in shop windows, sup- port from the regional government and ex- tensive sponsorship from local and national businesses.
Today’s freeflight technology First, let’s look at some of the technology used by today’s freeflight aircraft. Gliders are limited to a 50-meter towline and to in- crease the height at the start of the timed flight flyers have used a so-called bunt launch. This involved accelerating the glider to the top of the towline and then, at release, the model pitches nose up. Half a second lat- er a clockwork timer (based on a Soviet grenade fuse mechanism!) then re-sets the stabilizer to put the model into a quarter bunt, and about a second after that again changes the stab incidence to the normal glide setting. Thus after launch a glider per- forms a vertical “S” and gains several me- ters of valuable height.
With the advent of electronic timers and
miniature servos, more subtle changes are possible. Now, after the initial nose-up pitch, the glider is re-trimmed close to a zero-zero incidence, which results in a ballistic near- vertical climb until the excess airspeed bleeds off and the quarter bunt re-trims the model for the glide. Some flyers get around one hundred meters this way and the models pull upwards of 25G at launch, so carbon composite structures are essential. The F1B class (Wakefields) are rubber- powered but restricted to just 30 grams of rubber. To use this as efficiently as possible (i.e. to get the model high) flyers test each batch of rubber to find which has the best energy storage capacity. They use a torque meter while winding so they know that each motor will deliver the same output. Because a wound rubber motor delivers its maximum torque at launch and then drops steeply to a “plateau” level, it is vital to use this first burst efficiently and most people use an automatic variable pitch prop that senses the change in torque. A clock- work or electronic timer alters the stabilizer incidence, the rudder setting and differen- tial wing incidence to keep the nose pointing up till the rubber motor runs out of torque and the prop blades fold to reduce drag for the glide.
DECEMBER 2013
Championships
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