f5j electric soaring

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F5J electric soaring Francesco Meschia

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F5J electric soaringFrancesco Meschia

F3J sans winch

WINCHES?

WE DON’T NEED NO STINKING WINCHES!

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

Competing in an F5J contest

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

Score distribution F3J

Score distribution F5J

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

Example of mass launch

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

Setting up an F5J sailplane

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

How to run an F5J contest

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

Thank YouSee you on the

field!