National Free Flight Society

SEN 3164

  1. Found at LH
  2. Altimeter Challenges
  3. Right Tool for the Job

Found at LH

I found what looks like either a tracker or an RDT. This was at Lost Hills during the 2023 endless October at the middle of field site.
Describe it in a private e-mail and we can make arrangements on how best to return it to you.
Paul  Crowley
E-mail:  usa2298@


  Altimeter Challenges
By Aram Schlosberg

Currently, altimeters can be used to challenge timekeeper’s time only in flyoff flights. In a recent European contest, the second place challenged the winner’s time. Inspection of the altimeter in the winning model proved that the timekeepers overstated the flight’s time by over 10 seconds.
CIAM recognizes commercially available altimeters in flyoffs. For EDIC-approved altimeters, the timekeeper records the serial number marked on the altimeter and confirms that the altimeter’s memory is empty. For other altimeters, a contestant must raise and lower the model a prescribed number of times to form a “signature” before flying the model. (Aliens would wonder what is happening.)

Why don’t altimeter challenges apply to all official flights? All official flights are equally important. Although flyoff flights are longer, regular flights can traverse a long distance in wind. And big thermals can trigger a mass launch, making it difficult to accurately track the right models among so many models in the air. It’s evident that altimeter backup information could be very helpful.

Altimeter challenges in regular flights are only worthwhile for maxing. Altimeters sample at a certain frequency and to guarantee a max the last air-borne reading must exceed the max by the sampling interval. The decision, of course, is left to the jury.

My guesstimate is that about 5% of the fliers in a regular round would be close enough to maxing to challenge their timekeeper’s time. It might be good practice, in large contests, to field more than one team along the flight line, dedicated to judicating altimeter challenges in a timely manner.

Over time, the dwindling and aging timekeeper’s pool will probably delegate most of the timing to altimeters. It’s time to allow altimeter challenges for all official flights in the next rule cycle IMHO.

Right Tool for the Job – Editorial

At a recent club meeting by Zoom club members who were at the recent World Champs gave a report.  Another club member who was not at the Champs    said something like  ”  what’s this Altimeter stuff, they are for measuring height not time”. And the implication was,  are we using the right tool for the job.
We did explain about challenging the timekeeper in the fly off etc. …

Behind all of this talk there are really a couple of underlying factors that we are not really addressing.  The first is we fly high performance models and we try very hard to get the best performance out of the model. We understand that there are some things outside of our control like the weather and thermals. We know that the more we practice the better we get, that is we do pre-flight checks the less likely bad things will happen.  I was at a World Cup a number of years back where the organizer supplied timers and one sportsman complaining to the organizer saying, “I’m a World Champion, I don’t want that old lady timing my model”.  Now as it happens in this case, “old lady” was a very experienced timekeeper with good eyesight and binoculars and focused properly on the job.  But that is not always the case and not always connected to the timekeeper’s age. BTW I can’t report on the rest of the conversation because it contained words I’m not allowed to use in SEN, she did say that she would never time that class again.  Timing a 4 second F1C motor by hand is rather boarder line and encourages some equally boarder line practices of gaming the timing and over run limit.

Our flyers put a lot of effort into their models and the organizers try very hard to get the best timekeepers.  But it just is not always possible. The sporting code imposes requirements that are extremely difficult to meet.  The ability to challenge the fly off times is a half baked slightly more polite way of doing what that World Champ did.  We “know”  that better ways of timing are possible because we see it in other sporting events.

In working on our models we like to use the right tool for the job. I was taught from a young age that when working on a nut and bolt I should hold the nut with a spanner, wrench, or socket, not with a pair of pliers.  The pliers might graunch or mess up the nut and not get tight enough.  Our using the altimeter is like using the pliers, it works, kind of, but deep down inside we know it’s not the right way.

The other issue is that there is a belief that the only person who benefit is the one who uses the altimeter to challenge the timer because that is the person who will  get more time because the model will be ‘seen’ for longer.   Now that is not always the case, we hear occasionally of people challenging the timekeeper and getting less. This is because the timekeeper is a person doing the job under trying circumstances and may give the sportsman the ‘benefit of the doubt’ or may even be timing  the wrong model give a better time.  If the sportsman or the team manager is smart that won’t challenge the timekeeper if the “official’ time is better that the altimeter time.  Some are just not well enough organized ! In talking with a couple of experienced Team Managers they believe that a significant number of people have got more time that they really earned.

Doing some form of automated flight recording is a quite a big change, it would not apply to all classes and all events. It involves both technical issues of determining the start and end of the flight, determining the right official flight was timed, how to handle events such as over runs , attempts, mid-airs, etc. that involve participation of a contest official.  We need to get these right . the object is to make this better for the sportsman and this includes making it easier for the contest organizer run an event for the competitive sportsman with a true sporting result.  Using the altimeters is a good starting point but we are not there yet. We need the right tool.

The organizers of the February contests are looking for a way of running parallel test at our  events where the event would be run in accordance with the sporting code but there would be an option to have the model timed with an onboard flight recorder as well. This would apply to the regular round flights as well as the fly off.  In addition to the official results, comparison information will be published on this parallel test.  The object of this is to provide information of what would be needed to do this  at a real event.  This is not just potential differences in time but on the mechanics of doing it and any issues.  This would address what both the flyer and organizer would need to do it properly.  There are many components such as practicality, cost, ability to fit existing models, civil aviation regulations,  domestic vs international issues, etc.  In Feb we would only do flight time, not F1C motor runs because that would probably require additional onboard equipment. We are looking at working with an existing equipment supplier.

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