National Free Flight Society

SEN 2085

Table of Contents – SEN 2085

  1. On Symmetrical Spliced Rubber Motors
  2. Eloy SWR
  3. Time Accumulation

On Symmetrical Spliced Rubber Motors

The main argument to use 1/16” rubber instead of wider rubber (1/8” and 3/16”) is to narrow the motor’s winding range, typically within about 20 turns. Some claim a smoother winding and more orderly buildup of coils starting above 300 turns.

1/16” rubber also has another interesting feature. Starting for a 1/8” segment (which is bounded by factory mark or being a bit lumpier) one can strip it into two 1/16” strips fed into two containers, that can be called left and right. The first motor made from the top of the left container is IDENTICAL to the first motor made from the top of the right container. (A pair of 1/16” motors are parallel for about 60 feet. And since each 1/16” motor is made from twice the length of a 1/8” motor, there will be a certain amount of mean reversion – the extraordinary sub parts of the original strip will be averaged out.)

Both a left and a right motor should to be broken-in using one’s favorite rubber torturing method. However, since the energy of the two motors is identical, only one has to measured. (A time saver to those who measure energy.) And if one of the pair turns out to be a ‘super motor’ or a ‘dog’, the same applies to its twin. Similarly, the number of turns of the first motor can be inferred its pair (over or under winding).

A good accounting system is required for symmetrical motors. I keep each (raw) motor in a 6 X 3” plastic snack bag, marked by its vintage, segment, the motor’s number and whether it’s a left or right motor.

I just stripped a segment weighing 475 grams of 1/8” rubber. The left and right containers weighed 235 and 240 grams; not bad. But after making 7 left and right pairs, the residual pair of motors differed by 5 grams – implying sloppiness of cutting the preceding raw motors. Evidently, sequential errors can accumulate. Another approach would be to slice a 1/8” segment into 60 gram portions and then splice each into a left and right 1/16” motors.

The effort to make symmetrical motors should only be applied to above average vintages. And if symmetry turns out to be a useful concept, our supplier might sell pairs of left and right 1/8”, 3/16” and 1/16” rubber.


Eloy Southwest Regionals
From: Peter Brocks

It is time to plan for the fun in Arizona in about 4 weeks! The 2016 Southwest Regionals in Eloy will be on January 16-18. For detailed information go to

Please pr-enter before January 1st – it will save you money. Attached is the FAI Entry Form. Please mail it together with a copy of your 2016 AMA Card and your check – it will make it much easier for me. The max. fee to enter any event (FAI, AMA, NFFS, SAM) is $50.00. Your check will only be cashed after the contest. You can also add the AMA Entry Form and one single check – I’ll then inform Al Lidberg.

The FAI SWR will be flown to the 2016 rules. Specifically we will fly only 5 rounds in F1ABCQ before going into the fly-offs. The max. engine in F1C run is 4 seconds. On Sunday we will also fly F1S (small electric power/E36). Please note that in case of inclement weather the Monday (Jan. 18) is a reserve day for FAI events. – I will be on the field Friday morning.

Thermals, Peter

Time Accumulation

The latest team selection time accumulation sheets, as of December 9th, have been posted on

In F1A 12 have entered the program of which 3 have qualified (Jim Parker, Shlomi Rosenzweig and Brian Van Nest) . In F1B 13 have entered and 7 have qualified (Carrol Allen, Paul Crowley, Walt Ghio, Charlie Jones, Richard MacCleery (Welcome!), me and Tom Vaccaro). In F1C 9 have entered and Matt Gewain has qualified.

At this stage, my guess is that we could expect another 3-4 in A, 5-6 in B and 2-3 in C, bringing the totals to 15-16 in F1A, 18-19 in F1B and 11-13 in F1C.

I realize that we are facing a considerable aging and burn out effect. However, AMA’s team funding factors in the number of participants in each event. Joining the program ($90) and even accumulating some time without intending to participate in the finals can really help. A call for more hands on board.

The official time keeper.

Roger Morrell