Author: Louis Joyner
Edition: Model Aviation - 2011/08
Page Numbers: 129,130,133
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Free Flight Duration

Louis Joyner [[email protected]]

The 2011 Symposium is available

2011 FREE FLIGHT World Championships: In F1A Glider, Russia scored a team first and team member Yury Titov took the individual title. The highest-placing American was Brian Van Nest at 12th.

In F1B Wakefield Rubber, Russia’s Alexander Milyutkin placed first and Alexander Andriukov of the US was second. Team first went to Israel and the US placed third.

Ukraine’s Eugene Verbitsky placed first in F1C Power. Faust Parker was the highest-placed American at eighth. The team prize went to Ukraine and the US placed second.

The National Free Flight Society’s (NFFS) 2011 Symposium is out. This year’s symposium editor, David Lacey, is focusing on the needs of the average free-flight modeler. “I have a number of authors writing tips and personal experiences to help the intermediate advance to a higher stage,” says David.

Some of the topics covered include trimming gas models, discus launch and catapult gliders, electric power for Flying Aces Scale, electric power and helicopters for Science Olympiad, selecting covering material and applied weights, engine balancing, and information for FF newcomers.

Subjects with a more technical focus include an explanation of the relationship between CG and tail volume coefficient, 3-D analysis of F1A towline gliders, and hand-launch gliding.

An exploration of the effects of aspect ratio and flight times points out that increased wing aspect ratio and the use of folding propellers are responsible for the dramatic increases in glide time for F1C power models.

Surprisingly, the altitude gained in the climb has remained relatively constant throughout the last 60 years as the increasing power of engines has been canceled out by shortening of engine runs by the rule makers. Cuts over the years have reduced motor runs from 20 seconds to the current five seconds.

Models of the Year chairman Mike Fedor, along with committee members Rob Romash, Dick Mathis, and Don DeLoach, selected 11 models for 2011. Two will be familiar to many modelers: Wally Simmers’ Gollywock rubber model, dating back to the 1930s and still competitive in Old-Timer events, and Tom Hallman’s Peanut Scale Mitsubishi 1MF1 biplane (featured on the February 2011 cover of Model Aviation). Other models selected include:

  • Tony Mathews’ F1B Wakefield with the Brian Eggleston (BE) low-drag airfoil (LDA) wing
  • Artem Babenko’s F1C Folder
  • Evgeny Gorban’s F1G Model 2010 Coupe
  • Jim Buxton’s record-breaking Amalgam 6 indoor hand-launch glider (featured in the January 2011 issue of Model Aviation)
  • Bill Gowen’s A-6 (indoor)
  • Tom Iacobellis’ Limited Pennyplane (indoor)
  • Jean Pailet’s Genie Redux 1/2A F1J design
  • The F1Q electric model by Matti Lihtamo and Serei Vorihvost

Modelers selected for the Free Flight Hall of Fame include Larry Coslick, Larry Davidson, David Linstrum, John O'Donnell, and Bill Vanderbeek. The late father-and-son team Bob and Bill Hunter, creators of the Satellite Gas design and Hot Stuff adhesive, were also honored. Rex Hinson chaired the Hall of Fame selection committee, which included Fred Terzian, Jim Juhl Sr., Abram VanDover, and Don DeLoach.

The 2011 Symposium is available from NFFS Publications; ordering information can be found on the NFFS website.

The British counterpart of the NFFS Symposium is the Free Flight Forum, now in its 27th year. The latest offering, edited by Mike Evatt, includes a rich mix of articles focused on construction and the practical aspects of free flight; there is very little theory in this year's publication.

Highlights from the Free Flight Forum:

  • Ian Kaynes, longtime editor of Free Flight News and chairman of the CIAM FF subcommittee, provides a thorough account of F1E slope-soaring gliders. He includes graphs showing the calculated effects of model weight and size on performance in different wind conditions and a detailed description of foam-wing construction for a windy-weather model.
  • Chris Edge describes a method for constructing an undercambered wing without a lower-surface jig, using an idea developed by Peter Allnutt with laser-cut ribs each fitted in a "border frame" that acts as a jig. This allows one-off wings and changing airfoils from root to tip. More information is on the FlyQuiet forum (see Sources).
  • Mick Lester offers a technique for rolling tubular carbon-fiber spars and an idea for cutting carbon cap strips with a small circular saw.
  • Neil Cliff explores innovative construction techniques including tubular spar construction from carbon-fiber stock, an unusual method for molding balsa D-boxes, and clever ways to make traditional stick-and-tissue fuselages for rubber models.
  • Bryan Spooner’s "Laminated Propeller Blades" explains using a spreadsheet to lay out a mold for rubber model propellers. Ray Elliott discusses single-blade propellers for F1B.
  • Peter Hallman explains the design evolution of the Irvine ISR-HS and HS15 engines.
  • Roy Vaughan and Peter Brown explain their approaches to electronic air-picking devices.
  • The edition includes a gallery of successful British models from the previous year, including Ray Hall's modified 1959 semi-scale gas model that won the Bowden Trophy.

Notable models featured:

  • Peter Brown's Coupe: delayed propeller release (DPR), variable-incidence tailplane (VTT), wing wiggler, and a larger-than-usual propeller of 520 mm diameter (roughly 20.4 inches).
  • Phil Ball's Waif Mk3 Rubber model, designed for British Open Rubber rules.
  • Mark Berns’ Spin-Up series of discus-launched gliders, designed to handle wind and turbulence; composite wings of carbon cloth vacuum-bagged over a Rohacell foam core.
  • Clive King's Chuckit: a low-ceiling indoor hand-launched glider with flexible wing flaps that deflect on launch for minimum drag; the 15-inch-span model weighs 2.5 grams.
  • Mike Smith's electric-powered scale model of the de Havilland D.H.10c biplane bomber: a multiyear project with a 66-inch wingspan and more than three pounds in weight. More examples are on the Free Flight Scale website (see Sources).

Copies of the 2011 Free Flight Forum can be ordered from Martin Dilly or from NFFS Publications.

Waif Mk3

One of the models detailed in the 2011 Free Flight Forum is Phil Ball's Waif Mk3, built to the British rules introduced a few years back. Unlike the unrestricted American Mulvihill rules, British rules limit rubber weight to 50 grams (roughly 1.7 ounces). Phil's model makes extensive use of carbon fiber to produce a stiff, light airframe; airframe weight is 77 grams with roughly 250 sq. in. of wing area.

Details:

  • Motor tube: made from two layers of 100-gram-per-square-meter carbon cloth; measures 32.5 inches and weighs 22 grams.
  • Wing: uses a carbon-fiber D-tube from Szabo in Hungary. Each tube weighs approximately 3.5 grams and is roughly 520 mm (20.5 inches) long. Originally intended for F1A stabilizers, the D-tube provides torsional and bending strength for the 22-gram wing. The trailing edge is carbon fiber and the ribs are carbon-capped.
  • Propeller: 25-inch diameter, 30-inch pitch, carved from 1/4-inch sheet balsa.
  • Rubber motor: 27 inches long and takes between 900 and 1,000 turns; propeller run is more than two minutes.

Dihedral sanding jig

After years of makeshift arrangements, I made a dedicated jig for sanding angled dihedral joints. Previous methods included propping up a wing half on a table edge and sanding or using a fine-tooth table-saw blade with a sacrificial backing.

The new jig consists of:

  • a base to guide a square sanding block,
  • a hinged section to hold the wing,
  • an adjustable block to set the angle.

Borrowing an idea from sine blocks used in machine shops, I used a piece of half-round molding on top of the adjustable block. For small angle adjustments the adjustable block can be moved closer or farther from the hinge. To extend the range, add one or more shims beneath the adjustable block.

Most of the jig is made from ready-made shelving material available at big-box home centers (plastic-covered particle board cuts easily with a table saw). The base measures 8 x 14.5 inches; the hinged top plate is 6 x 11.5 inches (cut one short end with a finished edge). There are two other pieces, each 3 x 8 inches. One is attached permanently to the base 2 inches from the end with a finished edge facing the base's narrow edge. Glue doesn't bond well to the shelf material, so use screws. Attach the top plate to the base with a short section of piano hinge.

The second 3 x 8 piece serves as the bottom of the adjustable block. Cut several 8-inch-long pieces of 3/4 x 1.5-inch pine for spacers; top one with a 6-inch piece of 1/2-inch half-round molding. Add or remove spacers for gross adjustments and move the adjustable block for fine adjustments.

To set the angle use a digital angle gauge. First set the gauge on the base to zero, then place it on the hinged piece and move the adjustable block until the desired angle is reached. Clamp or screw the adjustable block down. Remember that the angle should be half the desired dihedral angle since you will be sanding both panels; sanding only one would result in unequal heights at the joint.

For sanding, use a 2 x 2 hardwood block (check that it is square) with medium sandpaper attached to one face. Add a 1 x 2 pine strip to the bottom of the 2 x 2, offset so it is flush with the sandpaper surface. The 2 x 2 will ride against the finished edge of the fixed 3 x 8 block.

Dimensions are not critical—make the jig any size you like. The important point is to ensure both the fixed and adjustable blocks are square to the base.

Sources

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