SEN 1995

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Table of contents – SEN 1995

  1. Now is Now
  2. F1S
  3. Nit Pick – ?
  4. Barron Field Activities
  5. Flapper Manifesto

Now is Now
From: Ross Jahnke

Dear Adrian,

I could build two Gollywocks in the time it takes to assemble and adjust a
modern “store bought” F1B. As far as I can tell the chase is at least as
long and the trees just as magnetic whether I’m flying my P-30 or my F1B
(and I don’t use a motorbike).

Thank goodness for the polio vaccine, airbags, and the computers upon which
we are able to communicate with each other, non of which were available in
the late 1930’s.

We all need to live in the present and be open to change.

Ross

F1S
From: Don Kaiser

I would like to see more FAI events offer F1S. With the popularity of E36 it seems like a no brainer. Don Kaiser

Editor’s reply -1

Don,
the F1S event at the Kiwi Cup/Ike was a test/pilot event added because of the vision of the CDs 🙂

F1S was on last year’s FAI approval agenda but was inexplicably withdrawn. It is back on agenda for the April FAI/CIAM meeting, so hopefully it will approved and added to the FAI rule book.
There is a lot of interest in the event outside of the USA. For example Henning has taken a number of kits back Denmark where it has been endorsed by such worthies as Thomas Koster and Per Grunnet.

There are also some International competition series and events for the FAI mini-events and these guys want to add F1S. It would be good to add it the America’s Cup along with the other FAI mini-events.

Editopr’s Reply – 2

Last weekend I was out at Perris with my 3 servo F1B, proving that even an airplane as clever as it is won’t fly properly if the pitch on one prop blade is wrong. When I got a F1S question from Stan.
There were a 5 guys working on their E-36 models. Stan reminded me that I had not properly commented on the (above) F1S event we ran in Feb.

As the CD what interested me the most was Don Kaiser’s reaction in the fly off. Don is a local, SoCal AMA gas flyer who with his father Ken has quite some success. In the F1S event Don made it to the fly off with Dick Ivers.
Dick is well known electric flyer from the East Coast who does both E-36 and F1Q. I thought it was great having 2 guys, one from each side of the USA in the fly off.
Don had never been in a FAI flyoff before. In AMA events you keep flying Maxes until you drop, you might never even see the other guys who you are flying off against.
But this event had Dan and Dick mano-a-mano with a level of excitement caused by the limited time frame and the two guys next to each other on the flight line. In the first flight both made the max. On the second they were going for 3 minutes and Dick flew first
making less than 2 minutes, Don thought he had it made as they both did well in the first flyoff, but Dick’s flyoff experience paid off as Don did not make 2 minutes either doing worse than Dick. Looked like the air was just getting worse as the fly off window progressed, not the first time that’s happened!

Sounds like Don is waiting for a chance to do better next time !

Nit Pick – or ?
Hi Roger:
You know how picky we Brits can be about the way you Colonials treat the Mother Tongue, so I am forced to ask if it would be possible to correct the typo on the SEN heading, so that it reads “contents” instead of “contnets”?

You will understand that the frustrations of not being able to fly are getting to me, and that I have nothing better to do than to harass the redacteur.

Cheers,

Bernie

It may be possible to correct the heading. However correcting the SEN type setters keyboard skills or the editors dyslexia is probably a bigger challenge.

In these days of spoofing, hacking, catfishing, plishing, Internet witch hunting our unique heading combined with the signature indicate that you have the genuine article.

Roger

Barron Field activity for April, May and June
From: Andrew Barron

Here is an update on free flight activity in Wawayanda, NY. The
Brooklyn Skyscrapers have their big meets May 30-31 for the Hatschek
International Challenge and June 27-28 for the Skyscraper Annual. These
are both America’s Cup and National Cup meets for FAI and AMA/NFFS
free-flight events. Also Ed Pelatowski concurrently hosts an FAC meet May
30-31. Less formal monthly Skyscraper meets are the second Sunday of each
month, beginning April 12.

A workday was previously announced to be this weekend. However, we have
appraised the status of bridges and find that we are in good shape. No
further construction is needed this year. So if you are coming to the
field this weekend, bring planes to enjoy flying. No need for bridge work.

Thermals,
Andrew Barron

A Flapper Manifesto

The Germans are proposing to ban flaps across the board for all FAI free flight models – to be voted on later in April in Lausanne. The stated reasons are to reduce building complexity/cost/potential-performance. In addition, the ease of enforcement, that more sportsman will have competitive (non-flapped) models and that flappers are still new and few. In other words, the concern is that flaps might increase performance and banning them would prevent free flight models from becoming even more expensive.

Flaps increase a wing’s camber in glide, while reducing the drag during the climb. Another effect is the reduction of the wing’s pitching moment during the climb that tends to pitch a model over. Deploying flaps can be justified in models with a large variation their climb’s speed relative to their glide speed. Otherwise, flaps are just ornaments.

A wing’s drag during the climb can also be reduced by using low drag airfoils (LDA). They are designed to prevent lower surface separation by incorporating a lower chin. However, the pitching moment of LDA airfoils is the same as conventional airfoils. Since their appearance in the mid 2005s, LDA sections have been applied primarily to F1As and recently to some F1B models. (In comparison, F1C fixed sections typically have low cambers that compromise their glide.)

Flappers are not new. They were widely used in the 70s before the advent of Carbon wings; Thomas Koster placed 2nd flying a one. However, current Flappers do not demonstrate any significant performance improvements over LDA models. Flapped wings have moving parts and hinges and can be deployed on outer panels, making them more prone to mechanical and aerodynamic malfunctions. So the choice of whether to deploy flaps, LDA sections or conventional sections involves many tradeoffs with no single ‘optimal’ solution.

Then there is the issue of blanket rule changes. Had geared engines been banned about twenty years ago, F1Q models would be precluded from using geared motors, as they are doing now. Another example was the reluctance to use composite materials in the 80s because of the concern about the safely of Boron. Had a general ban on composites been decreed, we might still be flying hard wood and balsa models.

And finally, to the difference between ‘what’ and ‘how’. The rules specify the energy budget of F1Q models. A few years ago a specification how a motor should be shut down (by an energy limiter) was adopted, but it created havoc in the electronic architecture. Fortunately the requirement was dropped. My point is that flaps or LDA sections are different approaches of solving aerodynamic issues and should not be specified by the rules.

Imposing a blanket ban on flaps intervenes in the heart of the wing’s design process. Banning flappers will eliminate a rich field of design innovations.

Aram Schlosberg

P.S. I have never built or flown a flapper and have no plans to do it in the future.

…………………………….
Roger Morrell