SEN 1999

Table of Contents - SEN 1999

  1. Now that we've polled ..
  2. Link to the poll
  3. 66th Inter City
  4. Allowing hinged surfaces - flaps
  5. The Dino likes flaps too
  6. Optimal Question ... and answer

Now that we've polled...

From:     Gene Ulm
I don't think those supporting draconian rule changes, in particular banning existing models or technology, are thinking through the consequences.

The cost associated with builder of the model rules, or more simply stated, banning nearly every model on the field world wide, is the most extreme.  That the rules would also destroy the resale market for these models only salts the wound.  What would the cost be world wide?  $500k+?

That doesn't sound cheaper to me. 

The costs of these and other rule changes that have the same effect (wing span limitations, etc) are so extreme they could mean the destruction of sanctioning bodies.  Model aircraft contests are not command and control; it is done by choice.   

With so much financial loss at stake there will likely be other sanctioning bodies that are organically born overnight to hold contests for these models to fly in.  When it comes to money, water always finds the drain  and modelers will vote with their feet.

Mini bans like those on flappers do the same thing just on a more moderate scale.  There is just more tolerance for it because fewer people fly them; "it doesn't impact me so why not?"

Besides so few people fly them are they really the source of the problem?  Not hardly.

It strikes me that most of the concerns about excessive model performance has more to do with excessive wind than excessive models.  Structure contests so shorter rounds are flown in the early am later pm.  Wasn't there a world champs flown in the am?

Cap wind speed. Wouldn't these things solve 75 percent of the problems in 75 percent of the circumstances and cut gripes more than in half? (56 percent).  And we haven't banned anything.

Want to cut expenses? Go back to two models, instead of four.   Model expenses cut in half.  No model is made obsolete thru banning.  Because four models are not needed it might be a boon to the resale market.  Economics 101: more of something results in cheaper prices and expenses will be lowered.   It works every time. 

Instead of bans to try to control behavior why not incentivize behavior instead.  Thinking out loud, remove the weight limits from f1a, b and c.     Existing models are still on the field, but there is the potential for more models.  Full auto-everything, but heavy,  may be one way to put time on the clock.  But a lighter weight locked down model might be a better way. 

I'm not saying that concerns out there are not legit.  There are just much better ways of dealing with them than banning.  And banning will be the most destructive thing we can do.  

Link to the Poll

 The link to the poll is:

  The NFFS invite everyone take a look at the results from the recent USA FAI proposal opinion poll. Note that the poll was conducted by a professional pollster and there were nearly 400 respondents.  

  66th Annual Inter-City Free Flight Meet

The Detroit Balsa Bugs are hosting the 66th Annual Inter-City Free Flight Meet june 20-21, 2015 in Muncie, Indiana. This is both an America's Cup and National Cup contest. Please email me if you'd like a contest flyer. This email address is being protected from spambots. You need JavaScript enabled to view it.

Allowing hinged surfaces (flaps) 

From:     Andrew Barron
In both full-scale and model aviation, variable position surfaces have
historically played an essential role and continue to play an essential
role in simplifying the control of aircraft.  This is true going all the
way back to the early implementation by Curtis of movable flaps in contrast
to the twisting of the whole wing by the Wright brothers.  Variable
surfaces are used on the vertical stabilizer, horizontal stabilizer and
wings of virtually all modern full-scale aircraft and on most model
aircraft (especially control line and radio control).  In FAI free-flight,
flaps on the vertical stabilizer (the rudder) are standard and it is very
common to have in-flight adjustments to angles of the horizontal stabilizer
(climb, bunt, glide and DT settings) and to the wing (wing wiggler for
differential incidence for climb and glide settings). Whereas, locked
surface models still exist in some AMA events, the overall lesson from FAI
development is that variable surface models allow the simplification of
separate adjustment of settings for the different phases of flight (e.g.
straight-tow, circle-tow, climb, bunt, glide, and DT).  Settings can be
separately optimized for each phase of flight.  Yes. This provides better
performance, but also potentially greater ease of flight.

Now it is true that there are some implementations of full wing flaps that
introduce complications in building, in trim, and in reliability.  Much of
this is due to the difficulty of maintaining flap position during the
bending loads on the wings during acceleration.  But this difficulty is not
necessarily an intrinsic one.  Just as there are myriad ways to hinge a
rudder, there are likewise many ways to arrange potentially simple and
helpful flaps on wings.  A main lesson is to avoid single full-length
flaps. Segmenting flaps allows them to better maintain position during
bending loads and can simplify their implementation.

The current alternative to wing flaps in high-performance F1A is the use of
a low drag airfoil (LDA).  These airfoils are highly suited to the
acceleration and climb, but are much trickier to get to recover well from
climb to glide, and much trickier to keep in good glide performance through
a range of air thickness and turbulence conditions.  Then there is the
challenge of the tow.  Low drag models require much faster towing and a
very different (and frankly less enjoyable) towing style than models with
wings that are cambered during tow.  At these high speeds crashes are more
common, and more expensive to our continued involvement. A number of F1A
fliers (particularly in the U.S. where the traditional towing style is
slower) are staying away from LDAs to preserve their enjoyment and their

Continued development of variable camber wings can move toward simpler and
more reliable implementations that allow for greater user freedom in
setting what he or she wants for the tow, climb, recovery, and glide

I believe it is essential to the spirit of FAI Free Flight in our premiere
events to allow this continued innovation.

Andrew Barron

The Dino Likes Flappers too

From:     michael achterberg
Rule proposals challenge.
Germany has propose banning flappers.
I must ask. Bernard u stated ease of building as an argument. Do you build your models? Do you fly the F1 events? As to cost, if they became popular the cost would come down. For the most part they  have shown not to be as popular as they once were in F1a, and F1c. In F1b the current World Champion new models are fixed wings an not flappers. An so we are banning a model design that few are flying? Interesting... I look at flappers as a interesting experiment that allows the mind to try to develop a technologically advanced model aircraft.

We all fly 20 yr old designs in F1b. For the most part all store bought, so for the few of us left in the world that build are own models and  that want to experiment with flappers, is that really a problem. It is not like you have to have one to win.. Actually quit the opposite is true. Alex flies fixed wings and I look at flappers as a way to possibly catch up a little.. What are the odds of beating the best in the world flying his model.. Slim to none. But maybe developing a better mouse trap you may have a shot.. Tony Mathews and Eggelston work on airfoils to try to close the gap. And they have a little. Tony has spent hundreds of hours data testing an many thousands of dollars in wing design.

So by your logic we should just choose one flat bottom airfoil for each class. Cheaper to build. No jigs required. Cheaper to buy. Massively less performance. Perfect answer.

 In F1 that is not what we are about. Never have been and I've been doing all my life. Well, tend to take off years at a time, but my interest has always been build a better mouse trap. We do this for the challenge. Developing ideas of what could be is a driving force in our events. Always has been , so be careful what you wish for..

Example. F1A was always a boring event to watch and to time.  Now it unbelievable to see these zoom launches that look like they were shot out of a cannon. Is there a contest that someone doesn't say Oh my god  did you see so and so on that flight.  Hell most of us turn around to watch these spectacular launches. It is awesome. Hope u and rule proposers dont take that away.. That would be a shame.

Next, these rule proposals as to 25 gr, heavy thicker tow lines, have not even been tested to see how they work. Just off the cuff, lets do this. 25gr will in fact widen the gap between the average flier and the few we call professionals. And there will be a bunch that will just quit cause they can't make the first 4 minute flight. Fact not fiction.. So there a rule change that will reduce interest, reduce participation and be the end of a very challenging event.  All I'm saying is that there are better ways to fix the perceived problems within our events. And yes I know this will fall on deaf ears.

Michael Achterberg.

Re: SEN 1998 and Optimal Tracking

From:     Dick Nelson
RE:  Optimal tracking.  Can you put this in English?????

...... Dick

Optimal Tracking's web site at
has French, German and English versions - just select the appropriate flag on the top right of the screen.  I'm not sure about Frederic's command of German but his English is very good, to say nothing of his French !

Roger Morrell