FREE FLIGHT INDOOR - 2003/08

FREE FLIGHT INDOOR

Bud Tenny, Box 830545, Richardson TX 75083

RECORD: Bob Wilder has again taken the lead in event 627: Indoor Electric Duration (Radio Control). At the UniDome in Cedar Rapids, Iowa, he had a flight of 20:57 — a substantial increase over the previous record time in that event.

West Coast Flying: Steve Brown reports that there is essentially zero opportunity to fly serious indoor events, such as F1D, on the West Coast. He is building new models to fly at the Kibbie Dome at the University of Idaho. How sad! That area can be considered the cradle of indoor as we know it today.

Fédération Aéronautique Internationale (FAI) Record Process

The following are excerpts from an e-mail Jim Richmond sent in response to questions about establishing FAI records:

1. Get an individual world record sanction ($2) and an FAI stamp. Do it right away. Be sure to give AMA precise info about the event and category (FAI #) you want the sanction for. I’ve never heard of any meet having an FAI sanction except a world championship, so always get an individual one.

You can order by mail or call it in to AMA (credit card). Amy Wilson in the Competitions Dept. is your contact person for this. This sanction is good for the entire year for a specific model type and ceiling category.

1. AMA requires that you notify them prior to each world record attempt, so e-mail Steve Kaluf ([email protected]) two weeks before the event (include the FAI info on the sanction so he will know what you are doing).

1. Although FAI doesn’t require the attempt to be made during an official AMA event, I think AMA does, and they want it to be able to qualify as an AMA national record if it exceeds the current one. Also, although FAI doesn’t require your two timers to be AMA members, I think AMA would require that, so don’t fight it.

1. Required participants: an AMA contest director, two timers (AMA members), three witnesses (minimum). Be sure to get the names and AMA numbers of these people if you wish to file a record application. Also, you will need the address of the contest director (for him to sign the documents).

1. Notification of a record performance: AMA requires that you notify them (Steve Kaluf preferably) within 48 hours after the record flight(s). FAI requires notification from either AMA, NAA (National Aeronautic Association), or the contest director within seven days of the event. This is a timing problem requiring your participation. The sequence is: from you to AMA to NAA to FAI.

1. Documentation: You will need the following in order to prepare your record application dossier:

• A time card with your flight times and the timers’ names signed in ink. You can prepare your own card for this.
• The names of the stopwatches used. You will also be required to testify that they had been checked for accuracy prior to the flight.
• A sketch of the cross section of the building showing the ceiling height.
• Recorded details of the flight(s) and other conditions such as temperature, outdoor weather, and any unusual difficulties or happenings so a descriptive story can be written for the dossier.
• A photograph and a three-view drawing of your airplane.

1. The dossier: This is an 11-page document requiring a number of signatures by the contest director. You need to get it completed, signed off, and delivered to AMA (Steve Kaluf) within one month. You can refer to the FAI rule book for guidance, but it’s very helpful to have a prior successful form on hand for reference.

Hope this helps. Let me know if you have questions.

Tan II Is No More

Rubber-model fliers were dismayed by the announcement that Tan II rubber will no longer be available because of a change in golf-ball construction. Balls with rubber thread wound on a central core have been replaced by balls using a different construction technique. This removes the only source for the Tan rubber.

Work had already begun on some lower-energy rubber designated "Tan Sport." A follow-on product called "Tan Super Sport" is also being made now. Fred Tellier has been conducting some tests on the new rubber as it becomes available. He wrote:

I did some revisited tests on Tan 5-99 after the World Champs and got energy readings about 5100+ and turns per inch of 171–173. Tan Sport gave energy readings in the 4600–4700 range with higher torque, 0.67 in./oz., compared to 0.62 in./oz. for 5-99.

I test all motors using strips 0.050 inch wide weighing 0.6 g. The 5-99 is less dense as it gives motors slightly longer—9 to 9.5 inch for 5-99 and 8.75 to 9.25 inch for Sport. The torque drops off faster in the Sport; later in the unwind the samples are close in value.

I think that if Super Sport is higher in energy it will be quite usable but not in the same class as Tan 10-97, 5-99, or 3-02.

I flew some of the Sport on a Limited Pennyplane and found it usable but not great. Again, I hope the Super Sport will be better. We have to use this rubber, but I think it will be hard to get enough turns so longer motors will be needed.

My ft·lbs./lb. numbers on most rubber have improved; I think my winding skills have gotten better allowing more turns in the test motors. In the formula, turns are equivalent to stretch so this greatly affects the results.

I test motors made up to F1D weight; break-in consists of winding to 0.3 in./oz. and holding for 2 minutes then increasing to 0.4 for 2 minutes. I test the next day and test each motor only once. I try to test five separate motors and average the results. I find for flying I can only get one safe flight from a motor, but if I test a second time I get more turns due to the extra length; this gives a higher ft·lbs./lb. value.

I am curious how others break in motors, as I get good turns but usually break on the second flight. I feel that we are not out of the woods on the rubber situation yet, but I think there is hope.

Flight Trim From the Brainbusters Newsletter (Edited by Abram Vandover)

Put this in your field box! This article is from an old newsletter and is by Jack McGillivray, but the information is still current and will help in deciding what size and length motor to use. I'm serious about putting it in your toolbox or in that book where you keep all your info — you do write it down.

Optimization of Rubber Motor Size

The object is to utilize the maximum number of turns wound into the rubber motor during an efficient flight. It should land on the floor just as all of the turns are used up. Following are methods of achieving this.

• Problem 1: Aircraft runs out of turns above the floor (overpowered).
• Solutions:
• Use another motor with a smaller cross section, maintaining or increasing its overall length.
• Use another motor with the original cross section, but with increased length.
• Increase the propeller pitch and/or propeller diameter.
• If the motor is new, the problem will diminish somewhat as the motor breaks in.

• Problem 2: Aircraft lands with unused turns left in the motor (underpowered).
• Solutions:
• Shorten the existing motor.
• Use another motor with a larger cross section, maintaining or shortening overall motor length.
• Decrease the propeller pitch and/or propeller diameter.

When considering solutions to Problem 1 or 2, keep these parameters in mind. If possible, the rubber motor weight should exceed the airframe weight, but should not exceed twice the airframe weight. On many aircraft, though, motors this heavy can't be utilized because of high wing loading.

When the motor length exceeds the aircraft motor base by more than 2½ times, vibration or risk of rubber bunching can occur, spoiling good flights due to center-of-gravity shifts.

With each successive wind on the rubber motor, the power output will fall, particularly when near-breaking turns are applied and an insufficient rest period between windings is not provided.

Limited Pennyplane is an example in which the 10-inch motor-stick length poses a problem in handling motor weights greater than 95% of the model weight. The most pressing problem is preventing motor bunching and the resulting loss of usable turns. This problem is most pressing in high-ceiling flying, where a longer loop is needed for the required turns.

Prime batches of Tan II could handle as many as five or six hard winds in one day and continue to be used until they incurred physical damage. Some data imply that the output of each successive windup is greater, not less, as applied to a Limited Pennyplane. This good rubber can be identified by keeping detailed records of stretch recovery.

The best 20-inch loop of 0.090-inch width will typically have a permanent stretch of 0.06–0.08 inch after the first wind. On subsequent flights it will typically return to almost that same length within 30 minutes after the flight.

To obtain this kind of performance from any motor made from Tan (I or II), it must be kept scrupulously clean. Tan II's surface is so smooth and slick that the tiniest piece of grit will score the surface.

Consistent use of Armor All, before winding and while stabilizing the knots during the final phase of winding, minimizes scuffing between strands. Several fliers have reported scuffing with most versions of Tan II, but it seldom happened under the hardest use when Armor All and similar lubricants were used.

MA

Transcribed from original scans by AI. Minor OCR errors may remain.