SEN 2259

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  1. Kiwi Cup First Round Start
  2. Stop watches from NFFS at Fab Feb
  3.  Use of altimeters in fly-offs
  4. Time keeping and fairness


Kiwi Cup First Round Start
The Starting time for the first round of the Kiwi Cup is moved from 8 AM to 10AM to allow for extra time people who missed sign ups and to allow for adjustment of the flight line.

Notification of the flight position will be given on the field. Wait in front of the camping area.

Advance notice of any schedule changes will be sent by SEN and posted in the Free Flight group on FaceBook.

Stop watches from NFFS at Fab Feb
This Just in! 15 new Accusplit stopwatches have been donated to the NFFS. They will be for sale at Fab Feb on the field. $20 chose a color Red, blue, yellow,green or black. See Glenn Schneider

 Use of altimeters in fly-offs
From: Tapio Linkosalo

Bernard Schwendemann pointed out a few potential shortcomings in the use of altimeters for timing flights in Free Flight. I also see some problems not addressed in the proposal to CIAM.

First, the proposed restrictions to model flying may be quite severe, limiting the altitude and weight of models to fly. In the preparation of the EASA legistlations there is a backdoor that “model airplanes” could have less restrictive rules than “drones”, based on their good safety record and practices. The prime difference between “model airplanes” and “drones” is that the former is all the time under the control of the pilot, and flown with direct visual contact. The “altitude logging” would promote flying the models beyond visual contact (as Bernard pointed out), and therefore put the models under “drone” category. I do not think this is a good idea. Rather I see it likely that in the next years the RDT will become mandatory even to our FF models, and the rules would obligate the DT to be triggered immediately when the fliers looses visual contact of the model.

Second, the proposed rules suggest that the model and logger needs to be retrieved and results presented to jury within 30 minutes from the end of the fly-off round. This puts fliers in quite different position depending on the size of their team. For a big team such retrieval is possible, when retrieves can go downwind and pick the model from the landing site (almost) immediately. But for a person flying alone, it would take 30 minutes to reach to the model, possibly 2 kilometers downwind.

And finally, I have my doubts about the timing accuracy of the altitude loggers. The devices are intended for measuring altitude, not time, and therefore they only use the internal resonator of the microcontroller to determine the time. Typically the possible accuracy of these resonators is no better than a percent or so. I recall some reports of digital servos, where the resonator is used to measure the servo pulse, showing considerable temperature dependent drift (due to the resonator == pulse length measurement) varying on temperature changes. So how can we make sure that the loggers measure the time with similar accuracy as our stopwatches do?


Time keeping and fairness
From: Allard van Wallene

We could ask ourselves the question, what is fair or unfair in free flight time keeping? Models with and without flashing lights (as is currently the case) have appeared in most fly offs over the last years. This has a strong influence on the recorded time. Yet, I did not hear of any competition protest about ‘fairness’ of flashers to date. Not to mention regular vs. LDA, geared vs. non geared, flapped vs. unflapped, bought and trimmed vs. home built and I can go on.

What is fair if a model is timed short due to poor eyesight of time keepers, bad (or no) binoculars or tripods, a model which disappears from view because of a car creating a dust cloud downwind. And I can go on. Use of an altimeter takes away all of this ‘unfairness’.

The tampering of electronics using a ‘faster’ time base to artificially boost the time can be easily checked by a jury. Put the altimeter on top of a car for 1 minute and then down on the ground. Any tampering will become immediately visible in the graph with disqualification as a result. A simple spot check does the job and faster than checking a towline, or surface area. Tweaking of a time base will also result in a non-functional communication with data reading equipment. And if a separate stand-alone altimeter (2 grams!) of 25 $ can be used, the argument that this is a technological burden in a 1k$ or more model is beyond me.

The organisational burden in a fly off can be reduced if a dispute is linked to an official protest where twice the price of an altimeter can be lost. If someone wants to dispute just for the fun of it, money lost and possibly an official flight time less than the recorded time by a time keeper.

The requirement of model visibility stands in the current rules and does not become obsolete just like it didn’t become obsolete with the introduction of LED flashers (or did it…?)


SEN Status
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Reminder :Fab Feb online entry form is available at:
It lets you sign up for all the FAI events at the Kiwi Cup, Ike Winter Classic, North American Cup, California Cup and The MaxMen International.  Held at Lost Hills from 11 to 20 February 2017.
All the latest information can be found at
Roger Morrell