National Free Flight Society

SEN 2682

  1. Why not Closed Loop
  2. Restricted and Controlled Free Flight Classes

Why not Closed Loop

From:Peter Martin

I noticed that there was no response to Martin Gregorie’s fascinating links discussing the ALOFT project.   I don’t know if you can include pics in a SEN newsletter, but I attached the main figure from that research, which shows the archetypal aims of a contest Free Flighter – Get State (check your thermistor) and ID Thermal (is it good enough to launch?!)

I didn’t realise my original aside on Facebook would unearth so much interest in closed loop control!   But now it’s out there, quite a few people have thought about it.   So here’s a controversial suggestion….   How about instigating a separate free flight class in which closed loop control IS allowed??  For those who want to explore the idea (I would be happy to help with defining the rules around closed loop).   I suppose the fear is that the tech will covertly find its way across to the traditional “open loop” classes, but we rely on honesty of our fellow competitors all the time and I believe we’re a very honest bunch!   There’s no prize money at stake, just pride.  And no pride to be taken in an illegal system, so I personally don’t think we’d have to worry.   Also, it may not be as easy to get an advantage as some think…!    Cue argument?

All the best,Peter Martin

PS  I suppose the other point is whether it would still be truly Free Flight.   Well, it definitely wouldn’t be Radio Control!  Rather than programming the model to follow a predetermined timed sequence after leaving the hand/towline of the competitor, it would be programmed to follow the predetermined on-board algorithm of the competitor.   The spirit is much closer to Free Flight than Radio Control, I believe – It’s still exploiting Aerodynamics/Engineering knowledge to fly for longer once the flyer “lets go”, not moving your thumbs on a transmitter with skilful hand/eye coordination?  (Apologies to any RC flyers on the list who don’t like my description!)

Editor’s Comments
Peter very interesting
Firstly we need to be a little careful not to increase the absolute beyond what we have already where we are out flying current fields and possibly running into civil aviation restrictions

While some of these ideas may upset the traditionalists they may be a way of bringing in new blood.

So how about this …

Restricted and Controlled Free Flight Classes

This document describes 4 possible Free Flight classes paralleling the F1A, B, C and Q but with means to accommodate the restricted flying sites that are becoming more common these days. These could be called F1AA, F1BB, F1CC and F1QQ.  As with the current Free Flight classes this is a duration event flown in rounds, from a flight line  with increasing flyoff times and no outside control during the flight. In the same way  the means of attaining the initial altitude is limited, length of towline, eight of rubber and length of engine run.

The differences are as follows;

The model flight must be completed inside an organizer specified “box , for example  1Km X 1Km X 250 m (altitude).  The size of the box can be changed by the organizer to fit the current weather and geography.

The maximum size of the model is a wingspan of 1.7 metres

The maximum weight of the model is 248 grams

Contrary to the current rules the model may, but does not have to employ a closed loop control system.

The model may employ a remote D/T system to terminate the flight.

The model must carry on board a standard, closely specified, certified monitoring unit. This is called the Timekeeper. More detailed information is below. This unit times the official flight and send the results back to the organizer.  The flight is considered to be finished when it touches the ground or flys out of the official box.  The Timekeeper may provide a  data stream in a standard format that shows the current position of the model and the size of the current official flight “box”.

Each Timekeeper unit is uniquely identified by the sportsman and the model. So it contains the FAI ID and model number for each of that sportsman’s models.

Associated with the Timekeeper are two additional units, the Director and the Pilot.

The Director is used to run the contest.  As part of the event sign up process the contestant information is entered in the Director. This includes the FAI ID and model number(s).  The contest director announces the max flight time and box coordinates before the start of each round. They are also entered into the Director. The Director broadcasts these to all Timekeeper units.  When a Timekeeper unit is turned on it requests that information from the Director. There is an indicator on the Timekeeper that says if the current round information has been received.

When the Contestant goes to make a flight he pushes a “About to make a flight” button on the Timekeeper. This responds with a positive or negative acknowledgement that he can make is flight, e.g is the round open, has he already made the flight for this round ? and that is positioned correctly. This means is on the flight line? Or on the pole if the event such as a World or Continental champs requires poles. He then has a time window to make the flight.  This window includes pre flight activities such as towing the glider, winding the rubber motor, starting the engine or loading the electric motor battery. It is anticipated that this window would be a fraction of the total round time e.g. 15 or 20 minutes for a one hour round and shorter for a fly off.  The organizer specifies this time.  The Timekeeper has another button that is triggered when the flight starts, by the tow hook on a glider and the start button on other classes.

When the flight finishes the Timekeeper radios the result back to the Director. During the flight intermediate flight information is also sent to the Director as an additional save guard.

At the start line there are additional observer officials that observe and report any infractions or adjustments that need action.  In a major event flown from poles there would be one observer per pole. Infractions and incidents would include mid-air collisions, parts falling off model, site forbidden actions such as moto flapping…

The contestant can have a Pilot unit and with this he can cause the flight to be terminated by a RDT-like action.  If there is a rules infraction such as an over run the contestant is notified by a message on the Pilot unit. The Pilot units displays the time of flight, GPS coordinates and altitude throughout the flight.  The GPS information on the Pilot unit can be used for retrieving the model after the flight.

Other Pilot units and the Director can see information about the flight but they cannot control it (i.e. terminate the flight) but an observer can.

It is important to note that the Timekeeper does NOT perform the functions performed by a timer in a typical free flight model. The model must have a timer, that for example controls the length of the motor run on a power model.  It is expected that the current timers will evolve into more of an auto pilot that both looks for lift and stops the model from flying outside of the box. It is also expected that some timer will get information from the Timekeeper such as the current max and  the size of the “box” and current position of the model relative to same.

Model specs.  The suggested model specs have the model size at about the size of a current F1H, F1B,F1P.  This makes the model size a reasonable compromise between transportability, performance and ability to carry the Timekeeper.  The Towline would be 50M, the rubber 25  grams, the engine 1cc with a 7 sec engine run and for electric max motor run of 12 seconds with max altitude at motor stop of 120m.  The max weight of just under 250 grams is suggested to align with threshold weight limits imposed by some civil aviation authorities.  The restricted flight area is a way of protecting us in the world of decreasing field size and encroaching regulations.  It also enables us to have flying site closer to centers of population facilitation the participation of the younger flyers.

The Director is able to directly feed the flight times to an electronic score boards on the flying site and on the Internet.

It is suggested that the Timekeeper, Director and Pilot be open source software.