Author: Louis Joyner
Edition: Model Aviation - 2001/01
Page Numbers: 146,147,148
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FREE FLIGHT DURATION

Louis Joyner, 4221 Old Leeds Rd., Birmingham AL 35213

Since a scale is almost a necessity for free-flight (FF) building, Hermann Andresen’s practical, in-depth piece about digital scales is a must-read for all modelers. For more-traditional weighing, Art Loneergan’s "Ratio‑Beam Balances" shows how to make a simple, yet accurate beam balance.

Several thought-provoking pieces address the future of FF, including Mike Woodhouse’s "The End of History?" and Rex Hinson’s "What Are the Real Flying Site Issues?". Both articles merit careful reading and additional discussion.

One of my favorite articles traces the development of a high-performance F1K model. Rudolf Hobinger and Aram Schlosberg’s piece on Rudolf’s Carbonator F1K CO2 design follows the project from rules evaluation to design and construction, including propeller design and construction details.

F1K (Carbonator) highlights

  • F1K model limits:
  • Minimum weight: 75 grams
  • Maximum projected surface area: 12 dm² (approximately 186 in²)
  • Maximum tank volume: 3 cm³
  • Contest format:
  • Five rounds with 120‑second maxes
  • Flyoff rounds use the same max; the motor must run on the ground for specified durations before launch (1 minute before the first flyoff, 2 minutes before the second, etc.)
  • Design and construction notes:
  • The model is essentially a powered glider with a very long-running motor.
  • Significant computer time was spent designing the propeller; the model uses a one-blade molded prop with a folding counterweight. Calculations show a theoretical advantage of up to 8% over a conventional two‑blade prop for F1K.
  • Construction follows modern trends with some twists, including an extremely thin stabilizer (1.5%).
  • The article is useful because it covers the "why" and the "how" of developing a high-performance design.

Symposium 2000 (34th edition)

Each year the National Free Flight Society (NFFS) publishes a Symposium collection to encourage investigation, discussion, and documentation of FF technical and theoretical aspects. The 2000 Symposium delivers a wide range of essays, from fanciful to highly practical.

Notable articles

  • "Atomic Powered Free Flight" by Orville Olm
  • Describes how small amounts of radiation can improve the energy release from rubber strip by more than 5%. Accompanied by a Ross Jahnke woodcut.
  • Evgeny Verbitsky and Doug Galbreath — geared F1C engine
  • Latest geared F1C version; gearing 4:1 allows a much larger propeller (315 mm diameter, 300 mm pitch) at lower speed for improved efficiency.
  • Approximate rpms:
  • Propeller: ~7,250 rpm static, ~8,000 rpm in the air
  • Engine: ~29,000 rpm static, ~32,000 rpm in the air
  • Radar-gun tests showed the geared model reached ~77 mph about three seconds into the climb; a conventional model reached ~65 mph at three seconds and peaked at ~77 mph by five seconds.
  • Peter King — "The Effect of Airfoil Geometry on Lift and Drag Coefficients"
  • Investigates how reducing camber and thickness affects performance. Includes usable graphs to show effects on climb height and total duration. Results show thinner isn’t always better.
  • George Batiuk — organizing FAI contests
  • Practical tips and the amount of work required beforehand to make a contest run effortlessly. Recommended reading for Contest Directors.
  • Hermann Andresen — digital scales
  • Practical, in-depth discussion (see note above).
  • Art Loneergan — "Ratio‑Beam Balances"
  • How to build a reliable beam balance for weighing model components.

Future and thought pieces

  • Mike Woodhouse — "The End of History?"
  • Rex Hinson — "What Are the Real Flying Site Issues?"

Both merit further discussion among the community.

Symposium ordering and membership

  • Order Symposium 2000 from NFFS Publications, c/o Robert McLinden, 3903 W. Temple Pl., Denver CO 80236.
  • Cost: $25 for NFFS members, $30 for nonmembers; postage $4 worldwide.
  • NFFS membership:
  • Send $20 to the NFFS Membership Office, 3317 Pine Timbers Dr., Johnson City TN 37604-1404, or $39 for a two-year membership. Dues include a subscription to Free Flight Digest.

Symposium 2001 submissions

  • Editor Ross Jahnke set deadlines for Symposium 2001:
  • Article proposals by November 1, 2000
  • First drafts due December 15, 2000
  • Contact Ross Jahnke:
  • E-mail: rossjahnke@prodigy.net
  • Mail: 1673 Belmont Ave., Baton Rouge LA 70808-1005

Ten Models of the Year (winners featured in the Symposium)

  • Bunt Bone — Don Zink and Vasily Beschasny (F1A)
  • PC-31 — Paul Crowley (F1B)
  • Diamonds — Dave Sugden (F1C)
  • Odyssey — Michael Achterberg, Faust Parker, and Bob Johannes (F1J)
  • Marie — John Kamla (P‑30)
  • Obsession — Robert Lipori (Mulvihill)
  • Bandit — Bill Lynch (F1U)
  • Pilote 800 — Joe Mekina and Norman Depoti (large Power)
  • Sweep Up — Stan Buddenbohm (Indoor Catapult Glider)

Special awards

  • Alex Andrjukov — variable‑pitch propeller hub for F1B
  • Rod Mogle — electronic timer for F1C

Free Flight Hall of Fame inductees (2000)

  • Cezar Banks (California) — noted indoor flier; six silver and one bronze medal across eight consecutive F1D World Championships
  • Ian Kaynes — editor of Free Flight News and longtime chairman of the Free Flight Subcommittee of CIAM
  • Thomas Koster (Denmark) — Wakefield Cup winner (1965), Power World Champion (1977), and Glider champion (1979; proxy for Per Grunnet)

Junior Team Congratulations

  • Austin Gunder (Red Lion, PA) — won F1J at the Junior World Championships in August in the Czech Republic. Austin maxed out and then maxed the five‑minute flyoff, winning by almost two minutes.
  • David Ellis (Guilford, CT) — reached the F1B flyoff, scoring 217 seconds (22 seconds from first place).
  • Congratulations to the entire junior team and thanks to team manager George Batiuk for his work developing the Junior program.

Bunt Bone (F1A) — design and construction notes

  • Origins:
  • Roots trace back to Bob Isaacson’s Wish Bone design (a Ten Models of the Year winner over two decades ago). The Bunt Bone adds bunt: the glider gains altitude during the zoom off the towline, then performs a quarter outside loop to glide position.
  • Structure and materials:
  • Reinforced for the high loads from bunt and zoom using modern composites:
  • Carbon-fiber D-box
  • Rohacell and carbon spar with carbon-sock wrapping
  • Carbon‑aluminum tailboom
  • Wing D-box construction:
  • Instead of many closely spaced balsa ribs, Rohacell foam is used between the D-box shell.
  • To reduce weight and epoxy usage, the foam is cut away in scallops and into a series of ribs: full support along the leading edge where damage is likely, reduced foam and epoxy in the rear portion.
  • Availability and pricing (manufactured by Vasily Beschasny):
  • Finished Bunt Bone with mechanical timer: $600
  • 84‑inch wingspan model: $300
  • Higher aspect‑ratio Big Al: $650 ($950 with electronic timer)
  • Mini Bone (F1H/glider): $400
  • Contact for purchase:
  • E‑mail: beschasny_f1a_nordic@yahoo.com
  • Vasily often attends contests in California and sells directly.

Rohacell supplier:

  • Composite Structures Technology
  • Box 622, Tehachapi CA 93581-0622
  • Tel: (800) 338-1278
  • Web: www.cstsales.com

Catapult and Hand‑Launch Kits — Stan Buddenbohm

  • Overview:
  • Stan produces a line of Hand‑Launched and Catapult Glider kits. He focuses on quality over flashy packaging.
  • Kits sold without plans; plans are available separately.
  • Products and typical prices:
  • Plans: $1 each
  • Catapult Glider kit: $7
  • Hand‑Launched Glider kits:
  • 18‑inch: $8
  • 24‑inch: $9
  • Pop‑up fuselages:
  • 24‑inch (hand‑launch): $10
  • 19‑inch (catapult): $10
  • Timers or hooks: shipping $2
  • Fuselage features:
  • Rectangular front portion with hinged carbon‑fiber tube boom
  • Hinge allows a simple pop‑up wing dethermalizer and includes a screw adjustment for incidence
  • Larger boom includes adjustable stab tilt
  • Shipping:
  • Plans: $1
  • Timers or hooks: $2
  • Fuselages or glider kits: $5
  • Order from:
  • Stan Buddenbohm, 5652 Meinhardt Rd., Westminster CA 92683-2423

Ordering Symposium 2000 (repeated details)

  • NFFS Publications, c/o Robert McLinden, 3903 W. Temple Pl., Denver CO 80236.
  • $25 for NFFS members, $30 for nonmembers; postage $4 worldwide.

(End of article)

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