National Free Flight Society

SEN 2247

SEN 2247 – Table of Contents

  1. Help in Making a list…
  2. Mathews on Motors
  3. How the Scramble Started
  4. Scrambled Vision

Help in Making a list…
From: Ross Jahnke

I’m finishing a list of NFFS Model of the Year award winners and need the help of my fellow modelers to do so. If you have any of the NFFS Symposium Reports listed below, please forward the following information: Category (large gas, small rubber, etc.) event (F1G, A gas, etc.), name of the model, and builder/designer.

1970, 1982, 1983, 1984, 1985, 1986, 1987, 1991, 1992, 1993, 1994, 1997, 2004, 2005, 2012

Your assistance is much appreciated.


Mathews on Motors

From: tony mathews? ?*On Hybrid Motors*??Aram mentions the use of “Hybrid” motors for F1B. In Canada we have been using hybrid motors for a number of years. Originally, we had converted to?1/16″ (1.6 mm) motors as a means to control the motor length more accurately than was possible with 1/8″ (twice the resolution for length variations). However as Aram mentioned, it is a lot more work to make up 1/16″ motors. And personally I have not found any other advantages somehave claimed (better winding etc.).??Hybrid motors was a solution we looked at to be able to use our 1/8″ (3.2mm) rubber that we had in stock. To calculate max winding turns, you need to know the motor length (ideally before and after break-in) and the stretch ratio. We pull our motors to 36 kg (80 lbs) for break-in and record the max length. This is used (with un stretched motor length) to determine max turns. Within a batch of rubber, we have found that the stretch ratio is basically consistent. Thus if you wish to try to make motors to provide a consistent number of max turns, it is important to try and control the?motor’s initial length. So our method involves finding the correct initial length (by making some motors and pull testing) and setting our stranding tool (basically a stick with two posts with adjustable distance) to that length. Then we strand motors and see how close they come to the optimal length.??We now only use 1/8″ motors (for new rubber). Some motors come very close to the desired length and will have an even number of strands (26 or 28 strands for example). Others will have a single strand come some fraction of a loop too short or too long. In this case we have the option to use a smaller cross section loop to make up the shortfall. We cut the?partial strand away and weigh it. A single strand of 1/8″ rubber (1/2 loop) weighs approx 1.1-1.2 grams. So a single loop of of 1/16″ rubber (1/2 the cross section) will weigh the same. We tie the 1/8″ rubber and add the 1/16″ loop beside it. Thus the resultant Hybrid motor has an effective uneven number of strands (25, 27, 29 strands etc).??In the case of motors that don’t come out near the 1/2 loop error, we strip some 1/8″ or 3/32″ rubber into even smaller cross sections (0.6, 0.8, 1.0 grams etc) using an indoor rubber stripper. Thus it is possible to create motors that would have an effective precision of 0.5 strands. For example, you might require a motor to have 25.5 strands in order to maintain your motor length tolerance. This is possible with hybrid motors.??For very good batches of rubber, our goal is to try and make all of the motors within a given “segment” (from splice to splice) end up as close to the desired optimal length (for max turns) as possible. Of course determining the “optimal” length is a topic for another discussion ;-)??Tony Mathews

How the Scramble Started
From Tahn Stowe

About the Scramble event that is being added to the Ike Winter Classic
What I had in mind was a version of the Australian Power Scramble ( Kiwi Aggregate) that would allow for greater participation than is currently “allowed” under the rules.??For those interested who don’t know, the event is as Roger said, only vaguely  related to F1C, in that it is a Free Flight event in which you have to (hand) start your IC motor (max 1cc) and launch your model from a  marked starting position each flight,  an accurate timekeeper who records each flight is necessary.??The rest is a little different. The max is 2 minutes (keeps the action close), there are no rounds and no flyoffs, RDT is not currently allowed, mid air collisions are common, you are allowed only one model (you can have spare wings and tail) the winner is the participant who logs the most time in the air ( 2 minute max and 15 second minimum) all stop watches are stopped at the end of the hour or half hour (we will do half an hour), and the time recorded regardless of what the altimeter reads.  You are usually allowed one helper / runner / fetchermite??Given that motorized retrieval is allowed  (almost expected) in Lost Hills  and not wishing to cause any carnage, or cardiac arrests,  perhaps we could allow each competitor to have multiple runners/helpers.  This way we can get a lot more sportsmen and sportswomen involved relay style..??I am currently working on 4 Flying Carpets equipped with Mills .75’s  any of which could be “customized” for a particular country / continent, Expressions of Interest welcomed.



Scrambled Vision
We asked Malcolm Campbell for some Scramble pictures from his collection and put together this portfolio for us.


SEN Status
Our new web site is online with archives of SEN going back to 1997 plus many items about FAI Free Flight. It can be found at
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New users can sign up at  this link  or at the SEN website

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