SEN 2031

Table of Contents - SEN 2031 

  1. Not all D/Ts are =
  2. Neither are the interpretations

Dino says not all D/Ts are equal

From:     michael achterberg
Better make sure everyone has same DT angle. 30 degrees DT is a lot slower than 45.. So if not all same angle not very equitable.. But sometimes it must be done to complete results.. It's free flight..
Thermals, Michael

Neither are the interpretations

Chris Edge‎ said  in FB group Free Flight Aeromodelling

Now that DT flyoffs seem to be gaining acceptability for FAI world Cup events, how would you optimise your DT for maximum duration ?

A supplementary question perhaps should be, what constitutes DT and therefore how can it be judged by a timekeeper if DT has occurred or not ?

And the following replied 

Johannes Seren In Bavaria we fly these fly offs a little bit different. If your model DTs before the end of 2 minutes, the whole flight until it touches the ground is counted. For example 118+35s = 153 s. If the DT is after 2 minutes, you only get the 120 seconds as maximum time. To be timed correctly you have to ensure a huge different between "normal flight" and "dt" and can't vary the dt angle that much.. The point I don't like about these fly offs is the possibility to change your rudder position. By setting it straight a f1a dts the same way like a f1b/c.
Thomas Weimer We've been flying DT flyoffs in GER for many years and last weekend I won one with 90+x mode at 10:00 in windy and thermal conditions.
I made 130 sec. DT with e-timer exactly at 90 then flat DT with rudder in glide position. I have this flat DT trimming in 2 models, only changed rudder not stab angle. Sometimes it workes, but sometimes normal turning DT.
We have the rule that late DT gives penalty. 2 sec late-4 sec penalty. Some don't have e-timers.
Chris Edge So what happens in GER if your DT doesn't work correctly in your DT flyoffs ? So, for example, the line that sets your DT angle gets caught around the DT arm and the tail angle is much less than usual. Maybe the model now loops and takes longer to decend. Would the timekeeper disallow that flyoff time ? CHE
Thomas Weimer I already lost one fo because another model made loops ( technical problem).
We don't have rules for that, just luck and bad luck. In general I don't like these flyoffs because the influence of luck and bad luck is bigger than for regular fo.
Tapio Linkosalo I agree; there is too much variation in the DT sinking speed to make timing a feasible option.

I'd rather see an altitude logger used, so that the measured altitude at 1 min or 2 min flight time would give you the result. Of course then there is the question of calibrating your loggers, but I think that is more easy to do than to make the DT sinking speeds comparable,
Ron Kreetz Its all about the height at DT-time. In NL we experimented last year with altimeter registration succesvolle.
Ron Kreetz succesfully to exclude DT performance of models.
Chris Edge If you move away from timing as the contest arbiter then we should consider something simple, rather than rely on more electronics in the model (ie altimeters) and yet another special model that can launch to 200m for a short flyoff. So, for example, you could position a circular paper target downwind and the contest winner is decided by who's model gets closest - the tip of the nose of the model in the exact centre of the target is a perfect result. Easy to set up, easy to administer, easy to measure, and you can film the whole thing so no arguments over the winner. We should consider all the options. CHE
Bogdan Lemut When using this solution timekeepers usually measure two times: time from launch till DT ('DT' time) and the total flying time from launch till landing ('total' time'). The difference between 'total' and 'DT' time is what counts for FO. So if you have DT time over the prescribed DT time, this overtime is taken into account, your score is lower. This must be especially if you have flyers with mechanical timers.
Of course - there is always problem of determining the DT time. And - all competitors must agree to fly FO this way.
It is just a kind of local rule - a deviation from FAI sporting code, but I have never seen it mentioned in FAI Jury report so far.
Allard van Wallene If the sportsmen decide to set their DT time at, say, 2 minutes and the timekeepers time from launch to landing, it is within FAI rules. After all, it is the total flight time which counts. The organiser can even set a regular 7 minute fly off max. But all flyers must agree. If however the time under DT is timed officially, this is clearly outside of FAI rules, even more so if it is not announced as deviation from the sporting code in the invitation. A DT of an F1A is pretty random. It can be slow, fast, spinning, looping, inverted, what ever. Clearly not within the spirit of the sporting code.
Bogdan Lemut One of basic principles that FAI Sporting code follows or instructs is that competitions have to be run in the best interest of all participants. Such solutions are just exeptions, a choice, an attempt to lower the risk of long, distant flying with many unwanted risks.
Local rules. True -it would be nice to announce such solutions in advance, in the invitation,if they were pre-planed. But they are not. They are just part of flexible improvisation of both organizer's and competitors. Another solution would be launch from hand, which is even bigger roulette.
I remember our Mura Cup in Tapolca in 2012. Similar weather conditions,even stronger wind. As contest director I was auditing competitors about such solution (1 min flight+ DT) during longer break because of the wind. Many of them agreed to it, but a group of North European competitors was against it,they even threatened us with official protest. So we had to go on with 5 min FO in 5-6 m/s or more wind on that field. Models were landing in the town...
Frédéric Aberlenc Sorry but it does not respect FAI rules. If a fly off is not possible, competitors have to share the first place. I hope that the CIAM will reject these fly offs.
Allard van Wallene In some cases it does: Max is regularly set to 7 minutes for 3 flyers. Without the contest director/jury/timekeepers knowing, all flyers agree to DT at 2 minutes. The fly off is started and all models DT at 2 minutes. It is perfectly allowed to DT early, in fact many with RDT already do it regularly if the model is high or doesn't want to risk landing in dangerous areas. All models land in say 124, 126 and 130 seconds. These are official flight times and the official ranking is perfectly within FAI rules. But a contest director can not force such a system upon a flyer if he disagrees.

Bogdan Lemut Of course, Frederic - all participants must agree with such solution. I find it the same as agreeing to first FO to be flown at say 7, 9 or even 10 min if this helps to avoid bad visibility or some other problem in later FO' s. On the other hand - If FAI allows that the ranking can be determined by a draw, it seems more fair if final results are achieved by some kind of flying. Good flyer must show his/her skills under many different conditions.

Bogdan Lemut Just on more observation - Not all organizers are ready to accept this solution even if competitors agree and ask them to make it this way. I remember a tie for 3rd place in F1A juniors on a competition in Zrenjanin 2 or 3 years ago. It was windy, models were flying in the direction of the river and high forest in front of it. Both juniors agreed to go for 1 min + DT, but organizer refused to run it this way, because it was not by FAI rules. (on the other hand they were skipping several FAI rules). Luckily, the wind came a little bit down in the last quarter of an hour before FO, models were saved.
Allard van Wallene Very strange. The organiser can set a regular max but they can never forbid flyers to DT early. It is a free choice.
Bogdan Lemut Not so strange Allard, They should be timing both times (one of competitors had electronic timer the other one mechanical). Organizers said they could not do it, they did not know how to do it.
Allard van Wallene OK Bogdan, that would be against the rules. But timing from launch to landing is perfectly legal, no matter what acrobatics happens in between (provided no parts are lost).
Frédéric Aberlenc Hello Bogdan, can you comfirm that all fliers agree for such Fly off?
Bogdan Lemut I know that usually organizers make a meeting of all FO entrants and they present their idea. Many times competitors themselves propose such solution. If my sources gave me correct info - they had such proposal on Saturday in Tapolca as well and Organizer was happy with it, they say - the forecast was not very pleasant for that and next day. (considering the size of the field)
Bogdan Lemut Allard, I know that it is not stricktly by the FAI book, but why not calling this 'a local rule' when accepted by competitors on the field. Local rules can not always be known in advance. To have only 5 rounds instead of 7 from SC is also a kind of a l...See More
Tamás Horváth I was the contest director, so I would like to say something about the Fly off in Tapolca.
It was a very windy and turbulent weather all day long. Just 3 people in F1A category made the 7 maxes. They decided to do this kind of Fly –off. We had three timekeepers each start poles (in FO). They measured the DT time and the landings too. If the DT time would be over 120s the score would be lower as Bogdan said before. Yes, it was a local rule, and as I think a good decision from the guys.
They had the possibilities to make 5 or 7 mins FO but then they maybe find their models in the town.

Editor's comment ... While not stated, there is clearly a desire to complete the (World Cup) Contest while all the participants are still around.  If it was just a club event yoy could postpone the FO to the following weekend or similar.  For a World Cup sometimes people travel quite some distance.  Otherwise for a tie I think they average the points for the tied places.

Roger Morrell