f5j electric soaring
TRANSCRIPT
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
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
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
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
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
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
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!
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
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
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
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
Typical contest schedule
• A 5-minute preparation times precedes a group’s 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
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
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
Typical contest schedule
• Once the motor is stopped, it can’t 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
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 you’re doing – height penalty can change things quite a bit
F5J scoring
Name TimeStart
HeightLanding
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
Strategy• It’s 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 it’s unclear, look at what other people are doing
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
FAI-approved limiters
• RC-Multi Altimeter by RC-Electronics
• Altis by Aerobtec
• UniLog by SM-Modellbau
• Price $75-$100
What is good for F5J?• Virtually anything that is good for ALES or eTD is
suitable for F5J
• Scratch-built is an option, as are foamies (Radian) or converted DLGs
• 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.
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
Performance
• Not really a concern in F5J
• Just check that you’re running within limits
• If you can climb to about 250 m in 30 seconds, you’re okay
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
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. A printer is useful for round-by-round printouts. The “Gliderscore” program helps A LOT
• Chris Bajorek from SVSS has a portable F5J system, which includes a big LED display for working time, wired audio (wireless coming)
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