Author: Louis Joyner
Edition: Model Aviation - 2012/05
Page Numbers: 112,114,115,116,117
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FF DURATION - 2012/05

FF Junior World Champs

by Louis Joyner [email protected]

The 2012 FAI Junior World Championships for Free Flight model aircraft will be held July 27 through August 3 near Ljubljana, Slovenia. The United States will be represented by Gina Barron, Logan Tetrick, and Michelle Barron in F1A Towline Glider; Sevak Malkhasyan, Brian Pacelli, and Peyton Tetrick in F1B Wakefield Rubber; and Taron Malkhasyan and Brian Pacelli in F1P Power. As of early February, the third slot in F1P had not been filled.

Once again, Brian Pacelli will do double duty, flying Wakefield and F1P Power. This year’s team includes a set of brothers, Sevak and Taron Malkhasyan; brother and sister, Logan and Peyton Tetrick; and sisters, Gina and Michelle Barron. George Batiuk will be team manager.

Gina, who will turn 10 during the Junior World Championships, will be one of the youngest contestants to represent the US in any world championships. Although her F1A towline gliders may span twice her height, she handles them with skill.

At a contest last fall in Seguin, Texas, Gina picked her own air for all seven rounds and was one of two contestants to max out; both fliers maxed the first fly-off round. In the second fly-off, Gina placed second behind a flier with 30-plus years of experience—her father, Andrew.

The Junior Team Committee, consisting of Jim Parker, Charlie Jones, Tom Vaccaro, and George Batiuk, is raising funds to help defray some of the team’s expenses. AMA covers travel, lodging, and entry fees, but extra support is needed.

In February, the Junior Committee raffled one of the late Bob White’s Wakefields, model number 23, which was the backup model when Bob won the World Championship in 1987. Bob’s winning model, number 22, is on display in the National Model Aviation Museum in Muncie, Indiana.

Also raffled was a quilt depicting all of the previous Junior World Championships sites made by Charlie Jones’ mother. Donations can be made by check to AMA and should be earmarked for the Junior Free Flight Team. You can also send a check directly to team manager George Batiuk, 576 Dana St., San Luis Obispo, CA 93401.

America’s Cup

The annual multi-contest competition for all of the FAI free flight events concluded this December. Here are the results:

  • F1A Towline Glider: Brian Van Nest (Gina Barron, high Junior)
  • F1B Wakefield Rubber: Blake Jensen (Sevak Malkhasyan, high Junior)
  • F1C: Faust Parker
  • F1G Coupe Rubber: Blake Jensen (Troy Davis, high Junior)
  • F1H Towline Glider: Mike McKeever (Gina Barron, high Junior)
  • F1J Power: Faust Parker (Taron Malkhasyan, high Junior and 4th place overall)
  • F1P Power: Glen Schneider (Taron Malkhasyan, high Junior and tied for 3rd place overall)
  • F1Q Electric: John Oldenkamp
  • F1E Slope Soaring: Peter Brocks

The America’s Cup, which was created by the Southern California Aero Team and is administered by Jim Parker, offers a multi-contest format that encourages modelers from the United States, Canada, and Mexico to compete in FAI free flight events. Points are awarded at each contest: first place receives 25, second 20, third 15, fourth 10, and fifth 5 points.

Additional points are awarded depending on the number of contestants flying in the event. Best results from four contests are counted. To encourage travel, only two contests at any one site can be counted; the other two results must be from two other sites. In the case of a tie, results from more contests are counted.

Detailed rules for the America’s Cup can be found on the National Free Flight Society (NFFS) website.

National Cup

The National Cup was created in 2003 to encourage participants to travel and compete at free flight contests across the country. Like the America’s Cup, the National Cup is a multi-contest competition; however, the National Cup focuses on AMA free flight events.

Contestants in each of seven categories accumulate points in the individual events within that category at contests across the country. To score points, contestants must place in the top five in an event. The highest six scores in each event are counted.

To make it truly nationwide, no more than two scores are counted from any single location. A seventh score can be added by placing at one of four exempt contests in each of the four NFFS regions. The exempt contests are the Southwest Regionals in Eloy, Arizona; the AMA Nats in Muncie, Indiana; the Rocky Mountain Championships in Denver, Colorado; and the King Orange Internationals in Palm Bay, Florida. A third score from one of the exempt contests is to be counted.

In 2011, there were 81 contests with 615 contestants posting scores in 1,762 individual events. The categories and the 2011 winners are:

  • AMA Power: Bob Hanford
  • Classic Power: Bob Hanford
  • Nostalgia Power (small): Bob Hanford
  • Nostalgia Power (large): Bob Hanford
  • AMA Rubber: Earl Griffith
  • Nostalgia Rubber: Don DeLoach
  • Glider: Tim Batiuk

Bob Hanford won all four of the power categories.

The National Cup includes a Junior category, which combines scores from selected rubber, power, and glider events. Sevak Malkhasyan topped this category, with Tyler Moore in second, only 14 points behind. Samuel Smetzer was third, Taron Malkhasyan came in fourth, and Elliot Plantner placed fifth.

Rules, detailed scores, and the 2012 National Cup contest schedule can be found on the NFFS website.

Two-Piece Wings

Fifty years ago, one-piece wings were the rule, even for large free flight models. In those days, before minivans and SUVs, large wings were often strapped upside down to the headliner of the family sedan for transport to the flying field. Today, many models use two-piece wings that allow more compact storage—often in a purpose-made model box that safely stores several complete models for a car trip or an international flight.

Two-piece wings allow easy adjustment of the relative incidence between the two wing halves as a trimming aid. This can be accomplished by shimming underneath the trailing edge on a two-piece wing, rubber-banded to a traditional pylon or rail system on the fuselage. The two wing halves can also be connected by a single wire running through the pylon or fuselage; often one half is located by a fixed rear pin and the other half with an adjustable pin.

The adjustable pin can be linked to a timer, either through a line or a servo, to change the incidence of the wing half at a predetermined time during the flight. Known as a wing wiggler, its use is nearly universal in the larger FAI classes of F1A Towline Glider, F1B Wakefield Rubber, and F1C Power, usually coupled with auto rudder and auto stabilizer.

For smaller models, such as an F1G Coupe d'Hiver, a wing wiggler can even be used as the only automatic surface. On my Coupes, I use a simple wing wiggler made from wire and tubing to control the left wing. At launch, the left panel is set several degrees negative relative to the right wing half. This provides a left rolling tendency during the initial burst.

After 5 to 7 seconds, a timer releases a line, allowing the left trailing edge to move down to the glide position. The result is a straight, near-vertical initial climb, transitioning into a right cruise and right glide. No other automatic surfaces are used. (Photographs and a detailed description of this wing wiggler can be found in MA's November 2010 "FF Duration" column.)

A two-piece wing requires slightly more effort during construction, but the convenience of adjusting the wing halves independently, as well as the compactness, make it worth the effort.

Two-piece wings are often heavier than a one-piece wing. The wing wire, sockets in the two wing halves, and the socket and additional reinforcing in the pylon or fuselage all add weight; this is partially offset by eliminating the center section reinforcements needed with a one-piece wing.

The wing wire is often the main offender concerning weight. In the past, steel wire has been the most popular choice. Typical diameters range from 3.0 mm (slightly less than 1/8 inch) for F1B, to 5.5–6.0 mm (less than 1/4 inch) for F1A and F1C. Steel wire can also bend during a hard towline launch or on DT.

Carbon fiber has been tried as a lighter-weight alternative. The weight saving can be significant. On his F1B models, Paul Crowley has tried substituting 1/8-inch-diameter carbon-fiber rod for 1/8-inch steel wire. "The weight saving was nice; 1 gram for carbon versus 4 grams for steel," he said.

But there were problems. "I found that the carbon-fiber rods would break after repeated use, usually on launch," said Paul. "But the break was actually promoted by hard DT landings. I believe that the shear load at the pylon was the cause; rounding the corners of the holes didn't help. The carbon-fiber rod is a bundle of strands and you start breaking them one at a time until the strands that are left can't take the stress of a hard launch or DT."

A solution is to protect the carbon fiber with steel. One method is to use thin-wall stainless steel tubing of the desired diameter and fill it with carbon-fiber tow wetted out with epoxy. This can be done by inserting a loop of Kevlar thread through a length of steel tubing, then using the Kevlar thread to pull a bundle of doubled lengths of epoxy-soaked carbon-fiber tow back through the tube.

For lighter models, such as F1G Coupe and other rubber models, carbon-fiber rods or tubes still offer the best weight-to-strength option for wing wires. The popular Burdov Candy G Coupe uses a purpose-made 4.5 mm-diameter carbon tube; carbon-tube pultrusions, available from A2Z Corp and CST, are offered in 3 mm, 4 mm, and 5 mm, which would be suitable for many smaller, lightly loaded models. (I have had no problems using the 4.0 mm pultrusion for the wing wire on my Coupes.) To avoid problems, frequently inspect and replace carbon wing rods or tubes.

Whatever you use for the wing wire, it must fit properly into sockets in the wings. Standard piano wire and the next larger size aluminum tubing fit too loosely. Aluminum tubing from K&S has a wall thickness of 0.014 inch. If you use 5/32-inch OD aluminum tubing, the ID will be 0.12825 inch; that's 0.00325 inch bigger than 1/8-inch piano wire. Not quite sloppy, but loose enough to potentially cause trim problems.

How do you get a perfect fit? One solution is to make your own wing sockets using a carbon-fiber sock. The sock (available from CST) is slipped over a length of wing-wire material or drill rod of the same size that is coated with release agent. (I've used a double wrap of 1/4-mil Mylar.) The sock is pulled tight and coated with epoxy laminating resin. Excess epoxy is blotted off.

After the epoxy hardens, the wire is removed, leaving a rigid carbon-fiber tube socket that's a perfect fit for the wing wire. For larger models, a second sock can be added over the first for extra strength. You can cut the socket to length for each wing half or, better yet, cut it to double length and build it into both right- and left-wing inner panels at the same time, ensuring accurate alignment.

Don't do as I did and glue the wing socket permanently to the wing wire. I was using it to align two main spar halves while installing the sockets. The carbon-fiber sock tubing I had made was porous enough to let some CA soak through to the wing wire. (I intended to tack the sockets in place with CA so the wing wire could be removed and the socket-to-spar joint filled in with epoxy and microballoons.)

Paul Crowley offers another option to ensure a perfect fit: "I run a pipe cleaner with epoxy on it to coat the inside of the aluminum tube, then I bore it out to size with a new, sharp drill bit when it's set," he said. (I've done it the other way around by brushing slow epoxy glue onto a long section of too-small carbon-fiber tube and hanging the rod up to dry.)

The wing sockets must be tied into the main spar structure. Ideally, the wing socket is sandwiched between upper and lower carbon-fiber caps in a full-depth spar.

For the pylon or fuselage socket, you can use a section of the carbon-fiber socket or make a custom-fit aluminum tube. K&S, supplier of the brass and aluminum tubing available at most hobby shops, produces a line of thick-wall aluminum tubing in a variety of ODs with a wall thickness of either 0.035 inch or 0.049 inch; the aluminum used (6061 T-6) is slightly harder than that used for the thin-wall tubing.

The thick-walled tubing can be bored out using the correct size drill bit, preferably on a lathe. Few hobby shops carry thick-wall tubing; an online source is Hobbylinc. Its website includes thick-wall aluminum tubing in a few metric sizes, as well as brass tubing in metric sizes.

The brass tubing has a 0.45 mm wall thickness, so it doesn't give a close fit on metric-size wire. For example, the clearance between 3.0 mm OD brass tubing and 2.0 mm diameter wire is 0.10 mm (0.004 inch)—too loose to use as a shaft bearing or wing-wire socket.

StarLink FliteTech Models

Michael Pykelny is the new owner of StarLink FliteTech. He took over from previous owner Larry Bagalini, who ran the mail-order operation for a number of years after founder Al Brush passed away. The new contact information is at the end of the column.

StarLink offers a variety of models and kits, ranging from Russian flier Andrey Burdov's F1B Wakefield and F1G Coupe models to innovative P-30 kits. StarLink carries an updated version of Bob White's Beau Coupe design and several Nostalgia and Old-Timer rubber kits.

Items for the shop and flying field, including a machined aluminum winding stooge and clear plastic storage tubes for tracking transmitters, are also available. Components such as motor tubes, front ends, propeller blades, and even wings for F1B and F1G aircraft can be purchased.

Parts are stocked to allow upgrading of older Burdov Coupe front ends. These include adjustable blade fittings and a replacement shaft that allows you to use a bobbin to connect the rubber motor to the front end, permitting winding without the propeller attached.

Sources

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