Free Flight: Duration
Bob Meuser
Sympo '80 — Final Call
Hurry — Sympo '80 Final Call. The NFFS is soliciting papers for the 1980 Symposium publication. Papers should address some aspect of the science or art of free-flight model aviation. Send a short abstract of your proposed paper immediately to Bob Dodds, P.O. Box 436, Rancho Santa Fe, CA 92067.
Improved Towhook — Hatschek Hook update
The circle-tow, zoom-launch tow-hook for Nordic gliders (see this column, May 1977) has been used by serious glider fliers in every country where glider flying is taken seriously and has an excellent track record. Bob Hatschek has designed a feature that can be easily added to the tow-hook to provide an automatic timer-start function: the DT timer starts operating when the tow-hook is unlatched.
Price: $20 in the U.S.; $21 to Canada, ppd by first-class mail; additional airmail rates elsewhere. A stamped, self-addressed envelope will get you instructions for adding the timer-start function.
Bob Hatschek 316 Grosvenor St. Douglaston, NY 11363
Modeler's Bookshelf — 1979 NFFS International Symposium Report
Not to be confused with the NFFS Symposium reports, the NFFS World Champs Planbook, or the NFFS World Champs Tech Task Force Report, the 1979 NFFS International Symposium Report covers papers presented at the symposium held at the 1979 World Champs. Each paper is presented in both French and English.
Included papers:
- "Differential Chord" — Merv Buckmaster (Australia)
Discusses the virtues of using a wider chord on the inside wing to compensate for its lower velocity; presents theory and practical results obtained with A-1 and A-2 gliders and with Wakefield models.
- "Propeller Design and Analysis for Modellers" — E. Eugene Larrabee
Larrabee (winner in rubber power at the 1949 Plymouth meet; designer of the Gossamer Albatross prop; Associate Professor, M.I.T.) presents a method for designing "optimized" props, a method of analyzing any particular prop, and applications to aeromodeling.
- "2 Coupes d'Hiver Aérodynamiques Comparées" — Jean Wantzenriether
Wantzenriether (a Catholic priest and experienced competition free flier) compares glide-test results for two Coupes with drastically different airfoils and draws surprising conclusions from the data.
- "A New Look at Propeller Airfoils" — Paul Van Leuven (Australia)
Van Leuven adapted a full-size prop airfoil around a mean line with more camber and produced a Wakefield prop markedly better than his earlier ones. He reached the fly-offs at the 1979 World Champs.
- "Our Experience with High-Aspect Wakefield Models" — Jean Claude Neglais (presented by Reiner Hofsaess, West Germany)
Discusses high-aspect-ratio Wakefields such as "Espadon" and "Espada"; includes three-views of five successful high-AR models.
The full report is 48 pages: $7.50 plus $2 postage and handling anywhere in the world. If you order other Sympo reports or the Planbook at the same time, the $2 postage fee covers the whole order. For the complete publication list or to order:
Fred Terzian 4858 Moorpark Ave. San Jose, CA 95129
SHOCAIR A/B
The model shown in the three-view was designed and built by Mark Woodrey, an 18-year-old from Burleson, Texas. So far it has taken five first places and a number of seconds and thirds at significant contests, including first in both A and B Gas classes at the 1979 Nats and second in B Gas at the 1978 Nats. It holds both Categories II and III B-Gas records for senior-age fliers.
Mark built a Shocer and smashed it at the 1977 Nats. Following that, he designed the Shocair, based on the Shocer but with a significant weight reduction. Mark received the Planesmen President's Award for best original design in 1978.
Albatross airfoil — Lissaman 7769
The Lissaman 7769 airfoil (used on the people-power Gossamer Albatross, winner of the second Kremer prize for crossing the English Channel) is a computer-designed profile. It may or may not be optimized for the Reynolds numbers typical of F/F models, but it bears resemblance to a very successful airfoil used by Peter Allnutt on one of his World Champs A-2 gliders.
Observations for model use:
- The nose radius seems large; the airfoil would likely require turbulators to encourage transition on the upper surface.
- The reflexed trailing edge tends to make the airfoil stable, allowing a smaller-than-usual horizontal tail or more tail loading by moving the CG aft.
- The trailing edge would need some thickening for F/F model applications unless you have very thin cutting tools.
Airfoil coordinates (Lissaman 7769):
Chord (%) Upper Lower 0.0 0.225 0.000 1.25 0.334 -0.164 2.50 0.496 -0.201 5.00 0.615 -0.230 7.50 0.706 -0.230 10.0 0.840 -0.216 15.0 0.926 -0.170 20.0 0.992 -0.138 30.0 0.897 -0.106 40.0 0.696 -0.091 50.0 0.486 -0.075 60.0 0.316 -0.060 70.0 0.181 -0.045 80.0 0.084 -0.030 90.0 0.041 -0.016 95.0 0.000 -0.008 100.0 0.000 0.000
Nose radius: 0.0184 (center nose circle 0.0185). Trailing edge angle to chord line: upper 4.50°, lower 0.90°. Airfoil proprietary to Aerovironment, Inc. Reprinted by permission.
FF Product Directory
One of the hassles in free flight is finding plans, kits, hardware, and supplies. The following is a partial directory of suppliers who sell by direct mail order. The list is not complete; many suppliers also sell through hobby shops. Information is based on material received after December 1, 1979.
- AME: see Aero Modeling Enterprises (Gewain, Matt and Gail), P.O. Box 11, Cerritos, CA 90701.
- Aero-Lite Model Supplies (Pilotte, Ron), 36659 Ledgestone Dr., Mt. Clemens, MI 48043.
Indoor supplies: wood, condenser paper, microfilm, torque meter, etc.
- Astro Flight, Inc. (Boucher, Robert), 13377 Beach Ave., Venice, CA 90291.
Electric propulsion flight and ground support systems, supplies.
- Baldridge, William, 1464 S. Lafayette St., Denver, CO 80210.
Aluminum Wakefield motor tubes, .57 prop, miscellaneous custom parts.
- Bill's Mail Order Hobby, 3803 W. Astor, Lee's Summit, MO 64063.
Telephone: (816) 524-1684. Y and O props, manufacturer.
- Blue Ridge Models (Hartman, Bill), 203 St. John's St., Arden, NC 28704.
Competition and sport rubber-power and HL glider kits, miscellaneous supplies. Coupe d'Hiver, P-30.
- Boucher, Robert: see Astro Flight, Inc.
- Bowers, Hurst: see Flyline Models, Inc.
- Brookstone Company, 127 Vose Farm Rd., Peterborough, NH 03458.
- Buzzer Model Airplane Co. (Toner, Edward J.), P.O. Box 124, Howell, NJ 07731.
Telephone: (201) 363-0456.
- Cal Aero: no longer active. See JIM Models.
- CHE Models, 18000 Eastwood Ave., Inglewood, CA 90304.
Telephone: (213) 674-1756.
- CFM Products, 722 Lenox St., Yreka, CA 96097.
Telephone: (916) 842-4076.
Transcribed from original scans by AI. Minor OCR errors may remain.
