National Free Flight Society

SEN 2465

  1. Wind breaks the weak link
  2. Bror’s Words
  3. In response to Martin
  4. More Martin
  5. Before you throw stone

Wind breaks the weak link.

From: john carter
Reply to Martin
The weak link idea does not work in practice if flying in high winds it’s easy to jerk the model and add a temporary high load when not in launch mode all subject to gusts etc.
Jc U.K.

Bror’s Words
From:Ron Marking

Dear Editor
I do not subscribe but only read SEN online.

The article by Bror Eimar reads as though he is describing current rules. I have discovered that they are in fact his proposals. I think this should be made clear to all your readers as soon as possible.

Ron Marking


Editor’s Comment.  Ron, I would see it as a clarification. Clearly a current contentious item is what “local rules” are permitted, if any  when it comes to resolving a tie when a regular flyoff cannot be flown because of weather conditions, lack of light,  lack of time, etc . The one that has been used is the D/T fly off, some people this it is outside the current local rules, others not.  Some people think it is an OK solution if nothing else, some think it should not be used.    With the increasing importance of the World Cup, the way of coming to a sporting conclusion at one event affects not only those people taking part in the event but the World Cup standings too.

InResponse to Martin
From:Bernard Guest

Hi All,
In response to Martin Dilly:
For F1B a half motor would require a completely retimed model. The burst, and cruise would both be shorter, this would require a separate program for an electronic model (not so hard but still annoying) and for a mechanical model it would require a flyoff timer disc. It could be done I think but it would add complexity.

A short run for F1C would similarly require a revised timing program, and ads the already difficult timer challenge for determining engine shutoff etc. will get event tighter (although the model would not be as high so …..)

A breakable line segment on F1A would require a completely different launch technique …. most top F1A flyers rely on a strong line pull to activate the programming in the timer (correct me if I am wrong on this F1A guys) …. I have a feeling that a weak link would require a revised hook program. Would all hooks work with the weak pull required? Would we have every flyer coming back with a broken weak link? Again not sure of the solution is practical with modern F1As.

Alternate solution:
First a question: What is a flyoff? Answer: it is a test of the modeller’s ability to achieve max height and optimal glide. The test is best conducted in morning or evening calm air to reduce the chance for “help” from the elements. The modeller who is able to get his or her model the highest and who has the best glide should win the flyoff. That said, we all know that there is often an element of luck in the flyoff; one model goes left into better air than the others who all go right, etc.
So, the variables we are interested in are height and glide slope (sink rate), both of which can be measured using modern technology. In a situation where wind speeds and/or field size prevent a normal head to head flyoff perhaps the situation could be resolved using a flyoff that is flown using a pair of contest altimeters with each participant flying in sequence. So CD attaches the first flyoff altimeter (FA1) to contestant #1’s  model … the CD activates the altimeter and contestant 1 starts their launch window (5 min) the model is launched reaches height, and glides for 30 sec. and is then DTed) … if the contestant uses maximum time to launch then the time for each contestant is about 7 min (start of launch window to model on the ground; F1B would be the longest because the model takes 40 sec to get to max altitude). While contestant 1 is retrieving (should not take too long because model DTed after 30 sec (70 sec for F1B). Contestent two has FA2 attached to their model and their launch window begins. By the time they have launched contestent #1is arriving with FA1 which the CD removes to retrieve flight data for the score board and clear the altimeter for contestant #3 etc. etc. The score on the board is: max Alt (m)/sink rate (m/s) = flyoff time (sec).

For a big contest there could be 3 or 5 altimeters so that the contestants can fly with closely overlapping launch windows (so for example, contestant #2 starts 3 minutes after Contestant #1 etc.)… also if wind speeds are high the glide time could be cut down to 20 sec to shorten retrieval times.

Pros and cons:
Pros –
1. This system eliminates the field size and wind problem while maintaining the competitive spirit, and height vs glide skill elements of the traditional flyoff.
2. An ordinary world cup event would only need a few altimeters, no need for a large investment and the same units could be passed around from event to event (they could even be shipped from one CD to the next).
3. This altimeter flyoff could even be more exciting than a conventional flyoff because you would see the earlier contestants scores come in before the later contestants fly so you would know what they have to shoot for; heightened drama etc.
4. No need for modification to airframes, energy budget etc. Just fly your model as hard as you can, as the gods intended.
5. Because the altimeters are standardized and supplied by the CD there is no chance for tampering with times and altitudes etc. If we get fancy we could even use a radio link altimeter that transmits the data back to the CD tent when Dt is actuated.
6. No need for hordes of timers .. no timers at all actually (so no timer related problems)….. maybe this should be the way we do all fly offs???
7. No long retrievals or down wind hazard issues.
8. Could decide contest in a single fly off rather than two or three.
9. Eliminate time disputes and accusations of cheating etc. So less acrimony and drama (unless we want acrimony and drama??)

Cons –
1. Requires some R&D to develop and test a viable flyoff altimeter that works consistently and is tamper proof (some of this work has already been done).
2. Requires that initial investment from the community to develop and purchase a pool of altimeters that can be used by the whole FAI community.
3. Requires a standardized way to attach altimeter to the model (part of R&D).
4. Takes more time to fly in series, but when long retrievals and the need for only one fly off round are factored in, it breaks even.
5. Flying in series could mean first flyer has better chance of launching in lift than last flyer (esp.true for early evening fly offs) – solution … random draw determines flyer’s launch slot (element of luck again).

Ok that is all I have … can’t think of more pros and cons.


More Martin
From:George Voss

Reply to Martin Dillys’ comment:  Funny, that’s what I said.  Shorter launch height is the answer.

Before you throw stones …
What we are looking at here are positive suggestions for how to resolve the fly off problem.  Is it something special like a D/T flyoff, an altimeter, an onboard timing device, …..

Or do we need some other form of rule change?

Our rules changes system is our National Aero Clubs (NAC) or the Free Flight Technical Sub Committee making proposals to the CIAM Meeting, where it is discussed and voted upon by the delegates from our NACs. In some cases the delegates are well informed and knowledgeable, in other s not.

In most cases the regular flyer has only limited knowledge of the proposals and very limited opportunity to discuss and understand the proposals.  SEN , which has about 1000 readers all over the World is one of the few places where the subject can be discussed, regular flyers voices heard and possibly sufficient advance information gleaned to be able to advise the NAC delegates appropriately.