13-Apr-24 - 07:41 PM

Thermal Circle Text - Thermal Circle 20

Written by Hayden Daley - 21 April, 2009.
Changes In F3B

Text by Hayden Daley

March 2009

F3B is an FAI regulated competition event. The rules and the changes to the distance, speed and thermal rules the F3B rules are strictly controlled by the governing body of aeromodeling the FAI, and changes to the rules have to be approved by this organization. Multi task soaring has had one major change that completely changed the event, the models and the type of soaring. The eight minute thermal task was changed to a ten minute thermal flight. The reason for this change was that it was possible to launch with ballast and achieve the original task time 8 minutes, without thermal assistance. The regulatory body the FAI changed the rules and know a ten minute task must by flown to win thermal rounds, essentially it became impossible to fly a ten minute flight by launching with powerful winches and ballast. The FAI also bought in rules to govern winch power and the sizes of the batteries used to power winches. These new rules changed the event and the result was a different F3B where competitions could be won or lost by one bad thermal flight. In Europe all these rules are enforced, the winches and batteries are checked and any illegal equipment will not allow the competitor to compete in that event. These changes in the F3B rules made F3B more difficult and another component was safety and also the emergence of many different people winning these events.

The best wing sections for the old rules, and they worked well with the new rules where the MH32, a classic wing section that provided superb F3B models for the old rules. The RG 15 was used for years by American and European competitors and won a world championship with the F3b model called F3B Eagle,designed by Joe Wurts and Daryl Perkins, the original design used the SD7003 and was changed to the RG15 section and was one of the best models in the mid 1990’s. The RG14A used on the Fletcher F3B model the came from the Netherlands and in the right hands was basically unbeatable. These models would do comfortable 18 second speed run, consistently, fly the thermal task well and provide good efficiency for the distance task. The RG12A was supposed to be better than the RG15 however I have not heard of a model using this wing section. The importance cannot be stated enough, when purchasing F3B models, what is the wing section, how does it perform and does it suit your flying style.

Years ago these where the right wing sections for the old rules, the eight minute rules. With the old rules and when the winch rules where enforced, smaller models launched higher on less power. The Fletcher and Eagle had about a 2.9 meter wingspan. When the Ten minute task was bought in models got bigger and the average size to improve the thermal performance was 3.1 meters. Most F3B models are now this size or slightly smaller or larger. The rules changed practice, most people flew less speed and distance practice and began to practice thermal soaring to achieve the ten minute task.

2.4 GHz technology has bought about a change in fuselage construction. You can know purchase 2.4 GHz fuselages, constructed to give better range on this spectrum. Previously with MHz transmission carbon fibre caused terrible problems with resonance on these transmissions. Certain channels caused the molded models with carbon fiber wing construction to have major problems with range and interference. The only way to fix these problems was to run the aerial outside the fuselage and certain channels worked better, provided better range and less glitching than others. Equipment for F3B 2.4Ghz soaring is know being developed with slightly longer aerials (2.4Ghz aerials are short) and the aerials project out of the nose cone, and the aerials are longer. Essentially running the aerial out side the fuselage provides better range. With cost of competing, and the price of new models 2.4 Ghz also prevents accidents in events where people turn on the TX to check the range, shooting down someone competing either deliberately or by accident. Costly models can be flown without the fear of this style of accident ruining your event/comp sailplane.

Approximately three years ago in Germany a new style of flying F3B occurred. Good pilots where flying the ten minute task, or out soaring the other competitors and winning rounds and a new style of model emerged. These models had less camber and where optimized mainly for the speed task and a bi factor was that distance scores where still okay. These models flew consistent easy 15-16 second speed runs, where the old models where flying consistent 18-19 second speed runs. The faster models where beating everything because of the less camber faster speed times and good distance score, the disadvantage to the new models where reduced thermal soaring performance. In a twelve round event, a pilot with good thermal skills and good distance scores and with the huge advantage in speed run scores these models began to win every event especially in higher wind speeds. The ability to factor the twelve rounds and the three second advantage in speed, most of the older, popular designs are being easily beaten by these new models. The only disadvantage was the need for good thermal soaring skill to win the event. The new sailplanes fly quicker and have less hang time, however the advantage in speed scores causes victories. Know the old “Classic” sections have basically disappeared and only F3B models with low camber sections are available. Models like the Shooter, Tool, Evolution, Ceres,Radical and others are winning.

New F3B models seem to be coming out every week, the best wing section for low camber F3B has not been found, I think we will also have classic low camber wing sections like the RG 15 was in the mid nineties for F3B,with new style F3B sailplanes.. Essentially the best low camber wing section will be found. I believe the camber will be reduced even less and that we are looking at a new world of development that will see F3B designs constantly changing for the best efficiency, the best design for the new style and way of winning F3B events. An interesting fact that must be repeated is that distance scores have basically not changed with the new models. The only major problem is the thermal task. The older models will thermal better in the right conditions and this disadvantage can only be solved with practice with new designs and the ability to search for lift and the need to search has been going since the change to ten minute flights was made.

The changes in F3B will continue as long as the FAI controls the rules, personally I would like to see a 250 meter launch distance, a 500 meter line, a 15 minute thermal task and six lap speed task. Essentially with a higher launch and bigger tasks the event would be more impressive to watch, harder and new models would emerge, more new technology. The German F3B pilots pioneered this style of F3B and they should be congratulated for the emergence of new designs, designed and built to win.

Hayden Daley

March 2009

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