SEN 2066

Table of Contents - SEN 2066

  1. Pieter on C
  2. Lost Hills Update
  3. Sierra Cup Flash
  4. Gil and Bill
  5. Rocky Mountain Caps
  6. krka cup 2015_cancelation_odpoved
  7. SEN Sign Up

Pieter de Boer on C

Dear friends,
Following the F1C- rule change discussions in all kind off media, on the
field and with privet persons, I think it is time to formulate a collective
point of view.
Collected arguments, measuring data and some small calculations are brought
together in this paper.
1.     This collective point of view should result in overruling the 4s rule
2.     The final result should be a democratic accepted set off rules for
the whole F1C community.
Best regards,
Pieter de Boer.

Pieter's paper follows....

A big hello to all,


The last few months, people from all over the world had lots of interesting discussions about new rules for F1C models. You can follow them in magazines like SEN and others, hear them on the flying field or in meetings at National Aero clubs.

Also a petition against F1C rule changes gets lots of support.


General feelings around F1C rule changes, predicts an upcoming disaster.


  • 50% or more from the actual participants will leave active F1C flying.
  • Most of fixed wing-F1C flyers loose there possibility to survive the first round.
  • The discrepancy in performance between non fixed- and fixed- wing models gets even bigger.
  • F1C flying is getting more dangerous for participants and visitors.
  • Last but not least; for most of us F1C flying gives no fun anymore.


To get more insight and background in the matter, I observed, studied altimeter figures and made some calculations on speed, (initial-, mean- and maximum-) acceleration and breaking.

All aspects are related to the current 2015 rules, i.e. the 5 seconds engine run.

All indicated times apply to F1C models with electronic timers.


1.     The straight- versus gearbox- engine.

1.1.  Straight engines accelerate and break faster (less inertia).

1.1.1.     Therefore electronic engine run timing for straight engines allows 4.2s, while for gearbox only 4.0s

1.2.  The conversion from electronic timer to mechanical action adds 0.2s (e.g. servo movement etc.)

1.3.  Engine sound travels for 0.3s from moment of engine cut to time keeper

1.4.  Reaction of time timekeeper can be up to about 0.3s (Age depending)

1.5.  More drag during gliding for gearbox decreases performance

1.6.  30g extra weight for gear and props is not acting positively.

1.7.  Where there is an efficiency loss in the gears, you gain efficiency in the propeller speed regime.

My conclusion regarding straight- versus gearbox- engines is that considering all pro’s and con’s, the one or the other give no significant advantage in flight time performance.

Such small differences should not be a reason to differentiate in ruling between straight and geared drive engines.


2.     Fixed wing models verses folders and flappers (non-fixed wings).

2.1.  Fixed wing air foils are a compromise for fast climb and glide performance

2.2.  Fixed wing models accelerate up to 4.1s; maximum speed is reached at engine stop.

2.3.  Fixed wing models suffer from high drag of wing during climb and transition to glide.

2.4.  Altitude measurements on fixed wing models show a climb up to 135 m.

2.5.  Non-fixed wing air foils are optimised for both climb and glide performance.

2.6.  Non-fixed wing models accelerate faster and reach constant (maximum) speed at 1.7s

2.7.  Non-fixed wing models have lower drag during climb but also during transition to glide.

2.8.  Altitude measurements on non-fixed wing models show a climb altitude up to 175 m.

2.9.  The effective electronic engine run-time will be about the same as under sub 1. (Deduct time for electronic conversion to mechanical action, speed of sound, reaction time of timekeeper.)

The result of this comparison should justify the idea to differentiate engine-run times.

Suggestion: Non-fixed wing models have 4s engine run. (3s. electronic + 1s. “action time”)

Fixed wing models have 5s. engine run. (4s. electronic + 1s. “action time”)

So roughly a reduction of 20% of altitude of non-fixed wing models. That means 175 – 35= 140 m.



Hopefully we don’t lose a large amount of enthusiastic F1C flyers with this adaptation.

The performance gap is gone, where the challenge gets quite the same for everybody.

All models stay competitive. No waste of investments. Developments for all kinds of F1C models stay open. Every competitor can make his own choice to use his best model for the circumstances. In this way F1C flying remains attractive for the whole F1C community.


Up to 2015 I tried to get two rule changes (free choice between castor and synthetic oil, to be supplied by organiser and radio activated engine shut down). With this story I add a third one. It would be nice to replace the contested 2015 rule change by another, which I will (we can) draft later. If the engine run proposal is not feasible, I’d like to propose the oil and radio activated engine cut rule changes for 2016.


Important for this exercise is a democratic agreement for the still enthusiastic F1C community. Therefore I ask you to spread this proposal, be critical, and make remarks and comments. At the end we can convince our national delegates to vote for an overall accepted democratic rule change.

With good intention,

Pieter de Boer.

This email address is being protected from spambots. You need JavaScript enabled to view it.

P.S. Can we start a forum to discuss this matter worldwide?

Lost Hills Update

Great weekend with two contests – full results later.  Brian and Janna Van Nest have taken over Juan and Zella Livotto’s California FAI Invitational and shortened the name to California FAI.  This weekend was classic “Livotto” weather – hot , clear sky , not too much wind and very difficult thermals, just like I remember from 15 years ago.  This year only the Sierra Cup was a World Cup event but Brian is working on something for next year.


Sierra Cup Flash


F1A (7 min FO)


1      Enes Pecenkovic

2      Shlomi Rosenzweig

3      Ken Bauer



1               Greg Simon

2               Troy Davis

3                Bob Piserchio


1               Henning Nyghen

2               Randy Secor

3               Ron Mc Burnett

Gil and Bill agree

I agree with Gil Morris, AMA is going to "self-destruct" by supporting "multicopters".
                                                 Bill Lovins(MMM, Denver)

50th Rocky Mt FF Champs caps
From:Don DeLoach

MMM club still has a limited number of RMFFC "trucker" caps available for $18 post paid. PayPal to the club address (This email address is being protected from spambots. You need JavaScript enabled to view it.) or mail me a check made to MMM. 
100% of cap proceeds go to club operations (our 27,000 flying site) I can also bring your cap to WESTFAC V next week.

Thank you in advance for your donation to the MMM Club.


Don DeLoach
831 E. Willamette Ave.
Colorado Springs, CO

krka cup 2015_cancelation_odpoved

From: Damjan Zulic
Dear Friends,

Aeroklub Krka have unpleasant duty to announce the cancellation of the Krka Cup 2015 due to weather situation. Organizers have today checked the flying field and concluded that after rainy week the soil is quite soaked. On the other side, the weather forecast predicts monthly quantity of the rain in next three days which will result in over soaked flying site and flooded surroundings. In such conditions we can not provide the normal event.

We apologise for possible inconvenience.

To competitors who have already payed the fee, the fee will be refunded.

Thanks for understanding

Aeroklub Krka


SEN Sign up

From: A. Modeller
Subject: Joining SEN

Hello Roger,

A. Sportsman  forwarded me SEN 2054 and suggested me (verbally) to join.

I am preparing to enter F1C completion.

Is it possible to join / subscribe? How exactly does it work?
Kind regards,

You go to the link below and sign your self up.

This will cause you SEN to be emailed to you.  SEN appears on an irregular basis as information appears.

You are welcome. even encouraged to contribute by sending contributions by email to This email address is being protected from spambots. You need JavaScript enabled to view it..

SEN does not publish images. Events results are best supplied in an Excel spreadsheet. SEN depends on the readers contributing.   

There is no charge for SEN.

SEN has about 1000 readers.

You can also view SEN online at
the NFFS Web site - and at the SEN Web Site

The SEN web site is only updated on an irregular basis.

Roger Morrell