F5J electric soaring
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This document discusses F5J electric soaring, a new FAI class for electric RC sailplane competition. F5J aims to provide a level playing field by limiting motor run time to 30 seconds and assigning penalties based on starting altitude. Competitors are free to choose their climb profile and must then rely on thermal soaring. Contests involve man-on-man rounds with shared flight times. Winning requires maximizing airtime while minimizing penalties from altitude. The format is affordable and easy to run, making F5J a fun and accessible electric soaring competition.
F5J electric soaring
- 1. F5J electric soaring Francesco Meschia
- 2. F3J sans winch WINCHES? WE DONT NEED NO STINKING WINCHES!
- 3. LMR limited motor rockets Some early attempts tried to replace winch launch with electric motor launch (a.k.a. winch in the nose) by limiting motor run time The more watts you can pour in, the higher you climb in those 30 seconds Extreme importance put on overall efficiency and powerplant optimization Quickly led to arms race ~6 kW motors, unobtainium ESCs and propellers
- 4. ALES altitude limited electric soaring The availability of suitable electronic devices made limiting the starting altitude possible Everyone climbs for max 30 seconds to max 200 meters, then the soaring task starts Level playing field Affordable: 300-400 W are enough to send a TD ship to 200 meters in 30 seconds Man-on-man contest format is possible
- 5. ALES altitude limited electric soaring Discussions typically arise around zooming More of a red herring than a real problem, but it spurred heated arguments in Europe
- 6. ALES altitude limited electric soaring Score compression is a concern Potentially worse than F3J The playing field is too level, altitude limit is usually too high Contests tend to become landing contests if the weather is decent At a world championship level score compression would be untenable
- 7. Enter F5J In 2010 a proposal surfaced for a new FAI electric soaring class Made it into a provisional class, F5J First contests were held in Europe in 2011
- 8. FAI F5J A man-on-man soaring competition Shared 10-minute working time, spot landing Launch by electric motor, limited to one climb, maximum 30 seconds run time Starting altitude is recorded and used to assign a penalty to the competitor
- 9. F5J height penalty It is the new trick in the F5J rules The competitor is free to chose how much to climb during the initial burst Each meter climbed costs half a point (or 3 points past 200 meters) Compare this with F3J: each second spent on tow is one point not earned, and gives 25 meters, so the penalty is only 0.04 points per meter!
- 10. F5J altitude measurement: how does it work? Each glider must carry a combination motor runtime limiter and recording barometric altimeter device Starting height is recorded as the maximum height attained between the moment the motor starts, and 10 seconds after the motor stops This is guaranteed to capture any zoom
- 11. F5J altimeter/limiter The device is to be installed in series between the receiver and the ESC. It stops the motor after 30 seconds and prevents restarts Various FAI-approved devices exist
- 12. Competing in an F5J contest
- 13. F5J contest format A contest includes a variable number (>3) of preliminary rounds, plus 2 to 4 final (fly-off) rounds In each round, competitors are divided up in separate flight groups Each group is a man-on-man slot: after the sound of start of 10-minute working time competitors may launch The models must land before the end of working time in order to get landing bonus
- 14. F5J contest format Landing bonus is less important than in F3J/TD (max 50 points for landing within 1 meter from spot) Scores result from flight time + landing bonus starting height penalty Scores are normalized to 1000 within each slot, so that each slot can be compared to the others
- 15. Typical contest schedule A 5-minute preparation times precedes a groups working time During preparation time the competitors proceed to their assigned launching/landing spots Competitors power up their models on the ground, this also initializes the altimeters Competitors wait for working time to start, while reading the air and deciding a strategy After the working time starts, competitors may start their motors and launch
- 16. Typical contest schedule Although not mandatory, in most groups all competitors launch at the very beginning of the working time Launch direction is the same for everybody, decided by the contest director Timekeepers start their timers when the model is launched Once models are airborne, each competitor may choose which direction to go
- 17. Typical contest schedule Competitors count down from 30 seconds, while reading the air and observing what the other competitors are doing Each competitor may stop the motor at any time, or wait for the limiter to kick in Strategies during the powered climb may vary: one can decide to climb fast and shut down, or speed horizontally with a shallow rate of climb, or any combination of these
- 18. Typical contest schedule Once the motor is stopped, it cant be restarted After the motor is stopped, a plain thermal duration task must be flown Since each competitor may choose a different starting height, not all competitors may be able to complete their working time When a competitor must land, he must do so within 75 meters of the assigned landing spot, or the score is zero The model must land before the end of working time to get a landing bonus After landing, but before shutting down the plane, the competitor or timekeeper must write down the starting height
- 19. Compared to F3J and TD Real man-on-man contest, with everybody in a group flying the same working time just as fun as F3J! Much easier to run than F3J: no teams required, just a timekeeper and/or caller No team protection necessary Not always easy to understand how youre doing height penalty can change things quite a bit
- 20. F5J scoring Name Time Start Height Landing Height Pnlty Raw Score Score A 9:58.3 180 40 90 548.3 996.1 B 7:22.5 150 40 75 407.5 740.4 C 8:40.4 40 50 20 550.4 1000 D 9:57.8 190 45 95 547.8 995.3
- 23. Strategy Its all about air reading, even more so than F3J Starting height determines not only how long the model can fall, but also how wide the cone of explorable airmass is How many thermals per acre can the day produce? what is the probability of finding one in your explorable airmass? Is it better to climb or cover ground? if you spot signs of thermal, go for it and stop low; if its unclear, look at what other people are doing
- 24. Example of mass launch
- 30. FAI height measurement The altimeter must be initialized with the model laying on the ground The altimeter will record the maximum height between the moment the motor is started and 10 seconds after the motor is stopped The device must be read by the timekeeper for scoring purposes, via either an internal display or an external one
- 32. FAI-approved limiters RC-Multi Altimeter by RC- Electronics Altis by Aerobtec UniLog by SM-Modellbau Price $75-$100
- 33. Setting up an F5J sailplane
- 34. What is good for F5J? Virtually anything that is good for ALES or eTD is suitable for F5J Just add the recording altimeter It is a good idea to be light, and be able to carry ballast Battery can be recharged at will. Two or even just one climb out on a single charge is sufficient.
- 35. My F5J sailplane Maxa 4 Pro Electro Same wing I already use for TD/F3J Electric-ready fuselage AUW 65 oz 3650 KV brushless motor, 5:1 planetary gearbox Castle Creation Talon 35 ESC, with 5/7A BEC Aeronaut 14x8 folding propeller 3S 850 mAh LiPo battery, 65 C discharge
- 39. Performance Not really a concern in F5J Just check that youre running within limits If you can climb to about 250 m in 30 seconds, youre okay
- 42. How to run an F5J contest
- 43. Organizational tasks Field size determines how many launch/landing spots are possible (15m/50ft apart from each other) Number of competitors and of landing spots determines number of slots per round One-day or two-day contest, depending on number of competitors (min 4 prelims + 2 fly-offs) Launch/landing spots must be marked Flight matrix must be prepared: can be drawn randomly and/or adjusted to ensure fairness, no team protection necessary
- 44. Technical needs Audio/visual signals for start of preparation time, start of working time, 2 minutes to the end of working time and end of working time Computer or CD player is necessary. Gliderscore program helps Chris Bajorek from SVSS has a portable F5J system, which includes a big LED display for working time, wired audio (wireless coming)
- 45. Do you want to try? F5J is fun! Chris Bajorek is promoting a NorCal League, http://www.rcgroups.com/forums/showthread.php?t=2383385 Don and I already took part in some contests Chris is looking to expand the circuit beyond Davis, so that it becomes a real league Could we run a contest or two in Hollister? that could attract some pilots from down south A few batteries or a small generator is all that would be necessary
Editor's Notes
- #3: People have long looked for a way to do F3J-style contests without the complication of winches and towlines for a while
- #6: zooming, i.e. using the limiters shortcomings to gain unfair advantage, e.g. by accruing kinetic energy before the limiter can kick in, and convert it into height when the limiter cant do anything
- #7: The playing field is too level everyone starts at the same altitude, no optimization is necessary, no tactical short tows
- #36: Technically, there is a wingspan limit of 4 m, so were already grazing the limit