Sound & Model Aeronautics
Howard Crispin, Jr.
Correction: A couple of errors slipped through in the February 1987 issue of Model Aviation. George Abbott, Raleigh, NC, first let me know of the inaccuracies. I apologize for the errors getting into print — I am pleased the articles are being read.
- The statement that the EPA ranked the average model engine at 78 dBA and recommended engines be redesigned to operate at 65 dBA is correct. The text then said that 65 dBA was "over five times less noisy." That is incorrect: a 13 dB reduction (78 → 65 dBA) corresponds to about 20 times less acoustic intensity. Remember: a 3 dB change is approximately a factor of two in intensity (twice as loud or half as loud).
- The second error concerned speed: the claim that doubling the rpm increases the sound level by 9 dB and therefore the noise is tripled is wrong. A 9 dB increase corresponds to roughly an eightfold increase in acoustic intensity (10^(9/10) ≈ 7.94).
Other considerations: George Abbott asked an important question that must be addressed — what is being done to study the relationship of frequency to model aircraft engine sound levels? AMA Headquarters has inspected sophisticated equipment that provides excellent frequency‑spectrum analysis and would be ideal for a top‑notch study. The obstacles are primarily cost and finding qualified personnel with the time and expertise to run the studies. As we study sound further, it is likely someone — a manufacturer, an individual, or the Academy — will need to fund and conduct such research. That should lead to developments that produce required thrust and speed while reducing the high‑frequency sounds common today.
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AMA News
Correction
Howard Crispin Jr. / Geoffrey Styles, Director, Public Relations
A couple of errors slipped through in the February 1987 issue. Key corrections:
- EPA ranking: 78 dBA average; recommended redesign to 65 dBA. The reduction from 78 to 65 dBA (~13 dB) equals about 20 times less acoustic intensity, not "over five times."
- Doubling engine rpm and sound: a 9 dB increase corresponds to about an eightfold increase in acoustic intensity, not a tripling.
(See main Sound & Model Aeronautics column for further discussion.)
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Toys for Tots Fun‑Fly
Giant Scale Squadron & Valley Flyers RC Club, San Fernando Valley, CA
- Background: In 1982 two San Fernando Valley clubs combined efforts with the Toys for Tots program (U.S. Marine Corps) to generate publicity for the clubs and contribute to charity.
- Features: Established nationwide program; possibility of U.S. Marines participating; easily accessible flying site; $10 entry fee for fliers; toys accepted from nonfliers.
- Organizers: Walter Clark (Contest Director, AMA 641) and Dennis Hargrove (Publicity Director, AMA 143537). Marines provided four Marines in dress blues on event day; strong media promotion followed.
- Results: Since inception over 5,000 toys have been collected at fun‑fly events and turned over to the Marines. The San Fernando Valley area collected over 33,000 toys in 1985 (largest single contributor). The 1986 Toys for Tots Fun‑Fly drew about 2,000 attendees despite cold, windy weather.
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New AMA Decal and Kit
- Beginning mid‑January, thousands of 1987 AMA membership kits were mailed. The kit is a one‑piece booklet (AMA Supply & Service catalog plus membership information).
- Included: AMA's 1987 decal sheet. The emblem that appears as a gold embossed circle is actually a multi‑colored decal intended for application on the inside surface of an automobile window — long requested by members.
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Mall Shows (Cont. from pg. 98)
- Benefits: Mall shows can attract new hobbyists, demonstrate muffler systems and quiet engines, and explain "silent flight" with gliders. Good PR helps clubs, the hobby, and the community.
- AMA Support: Brochures, handouts, films, table‑top display booths, sample press releases/radio announcements, and videotapes are available.
- History: The National Mall Show Program began in 1983 and has grown; participating clubs have boosted the national image of model aviation.
- Contact: Have a club representative contact AMA Headquarters for a free starter kit with hints on successful mall shows.
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1988 Frequency & Identification Status
Bob Underwood, Technical Director
Spread the word: FCC action in 1983 granted new frequencies in the 72 and 75 MHz bands for model use. The so‑called "old frequencies" (72.080, 72.160, 72.240, 72.320, 72.400, 72.960, and 75.640 MHz) are no longer legal for model operation after December 20, 1987. Those frequencies remain heavily used by industrial users.
A new flag identification system becomes operational June 1, 1987, and will be required for AMA‑sanctioned activities in January 1988. The following summarizes the 1988–1991 channel plan and identification.
#### 1988–1991 72 MHz Aircraft Frequencies
- Channels reserved for aircraft use (channels listed with frequencies):
- 12 — 72.030
- 14 — 72.070
- 16 — 72.110
- 18 — 72.150
- 20 — 72.190
- 22 — 72.230
- 24 — 72.270
- 26 — 72.310
- 28 — 72.350
- 30 — 72.390
- 32 — 72.430
- 34 — 72.470
- 36 — 72.510
- 38 — 72.550
- 40 — 72.590
- 42 — 72.630
- 44 — 72.670
- 46 — 72.710
- 48 — 72.750
- 50 — 72.790
- 52 — 72.830
- 54 — 72.870
- 56 — 72.910
- Notes:
- Channels 12–34 — Narrow‑band transmitters only.
- Channel 36 and 58 not used — see General Info.
#### Identification (72 MHz aircraft)
- Single RED streamer — 7/8 in. to 1 in. wide by 8 in. long affixed to the top of the transmitter antenna, imprinted:
- "72 MHz AIRCRAFT USE ONLY"
- Channel number plaques — black numerals 1/2 in. high on white background, visible on both sides; may be mounted horizontally or vertically at modeler’s option. Non‑reflective materials recommended.
#### Other Bands (Model Aircraft or Surface Models)
- 27 MHz: Single colored streamer or triangular flag — 7/8 in. to 1 in. by 8 in.
- 6 Meter: Amateur Radio License required.
- 50 MHz: Single BLACK streamer 3/8 in. to 1 in. by 8 in. and channel marker plaque.
- Channels:
- 00 — 50.800
- 02 — 50.840
- 04 — 50.880
- 06 — 50.920
- 08 — 50.960
- 53 MHz: Two colored streamers 3/8 in. to 1 in. wide by 8 in. long.
- 53.100 — Black‑Brown
- 53.200 — Black‑Red
- 53.300 — Black‑Orange
- 53.400 — Black‑Yellow
- 53.500 — Black‑Green
- 53.600 — Black‑Blue
- 53.700 — Black‑Purple
- 53.800 — Black‑Gray
#### 1988–1991 Surface Frequencies (75 MHz)
- Channels:
- 62 — 75.430
- 64 — 75.470
- 66 — 75.510
- 68 — 75.550
- 70 — 75.590
- 72 — 75.630
- 74 — 75.670
- 76 — 75.710
- 78 — 75.750
- 80 — 75.790
- 82 — 75.830
- 84 — 75.870
- 86 — 75.910
- 88 — 75.950
- 90 — 75.990
- Identification: Single YELLOW streamer — 7/8 in. to 1 in. wide by 8 in. long affixed to the top of the transmitter imprinted:
- "75 MHz SURFACE USE ONLY"
#### General Info
- Effective January 1988, channels 12–34 reserved for narrow‑band transmitters only. Older broad‑band and newer narrow‑band equipment may operate on channels 38–56.
- Channel 36 is not used to provide 80 kHz spacing between channels 34 and 38.
- Channel 58 is not used to provide image response protection for channel 12.
- The channel usage and identification is authorized for AMA‑sanctioned events and recommended for all sport flying and club activities.
- See pages 127–129 of the 1986–87 Official Model Aircraft Regulations for current frequency info and recommendations.
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Sound (continued)
- New equipment: Progress continues toward quieter equipment for the average flier; some quiet solutions may be costly but necessary to preserve flying sites.
- K&B engines: Earlier tests showed the K&B Sportster .20 to be relatively quiet. A new K&B design (.45 cu in) with the same muffler design was due on the market in January; if it matches the .20's quietness it could be an excellent sport engine for Pattern competition without high cost.
- Magic Mufflers: Air Show teams and clubs report success using Magic Mufflers to reduce sound. The "S" version (introduced in 1983) adds an extra baffle and a perforated tailpipe chamber to absorb more sound. Cliff Rausin of Condor Models reports success with the Magic 40/60 "S" mounted about 5–5½ inches back on .61 engines (O.S., Rossi, SuperTiger, YS) using props such as 11½×9 Wide and 12×6–10, and running 15% nitro.
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Team Manager
Bob Wallace, Avon, CT
- U.S. team selection: Trials in Smyrna, TN produced a strong 1987 FAI pylon team; several entries broke the existing FAI Pylon Meet time world record.
- Team fundraising: A five‑color embroidered patch is available for $5.00 (postage paid). Limited edition patches have heat‑sensitive adhesive backing for easy application. Order to:
- United States FAI Pylon Racing Team Fund, 91 Sylvan St., Avon, CT 06001.
- Nationals: 1987 Nats to be held in Lincoln, NE, July 11–19. Pattern schedule changes and assigned frequencies by class will be used; Q‑500 offered for the first time this year.
- Pattern contests: Bridgewater Pattern contest — June 20–21, 1987. Ponderosa RC Hawks of Berwick, ME — planning first Pattern contest in August (dates TBA).
- Short subjects:
- Fifth District I newsletter sent in December; check with club contact if not received.
- New sanction form printed on blue stock — use current forms and destroy old ones.
- Obituary: Dwight Holley of Connecticut has passed away.
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Goldberg Vital People Award
- Debra Scott Justice (Bensenville, IL) received the Beth Carl Goldberg Vital People Award.
- Deb and her husband have been key to the success of Miniature Aircraft Competitors (MAC), AMA Club #1279. Deb founded MAC in 1982 and has served in numerous roles: president, flight instructor, PR director, contest director, secretary‑treasurer, and newsletter editor. Nominated by Lee Onopa.
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District Roundup
- Examples of district activity noted:
- Minnesota RC Soaring Society planning an electric event (seven cells max) in 1987.
- Tractor theft insurance warning from River City RC News — check insurance coverage for stored equipment.
- Glassfield planning a flea and swap meet in May.
- POMAC advises carrying a Halon fire extinguisher — echoed by Blackhawk Area RC Club.
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Safety Note & Yuletide Mail Bag
- Safety gadget: Tom Waller (Blue Angels club) sent a photo and description of a homemade "finger fender" constructed from discarded stack chairs — an inventive local safety device.
- Yuletide letters:
- Dan Domino (indoor flyer, East Windsor, NJ) notes scarcity of flying sites and suggests tax incentives for landowners who permit fields to be used for model flying; also advocates awarding trophies to 3rd place in all Nats events.
- David M. Schnitzer (West Windsor Flying Club, AMA 449) reports club activity at Mercer County Central Park (membership ~40), winter flying when weather permits, posting of the AMA Safety Code, and plans for the new year‑round AMA patch. He also supplied a photo from the club's November 1986 "Turkey Fly-In."
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The Latest from ModelNet (AMA's Computer Network)
- ModelNet is available via CompuServe. More than 2,000 modelers use it to communicate, read articles, swap newsletter items, find clubs and hobby stores, and receive pictures.
- Features:
- 14 message boards dedicated to facets of the hobby.
- AMA Executive Council members participate and answer questions online.
- Data Libraries (D14 and others) include lists of AMA‑chartered clubs, contest calendar, and a directory of over 900 hobby stores.
- High‑resolution graphics files are available for those whose hardware/software supports them.
- Contacts:
- For more information contact Doug Pratt at AMA HQ.
- If you are a CompuServe subscriber, type: GO MODELNET.
- Electronic mail to AMA: 76703,3041. Public/private messages can be left for listed AMA contacts (Don Lowe, John Worth, Howard Crispin, Pete Waters, Dick Crowley, Dave Pelz, Ed McCollaugh) at the indicated CompuServe addresses.
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VI District Report
Jim Sears, District VI Vice‑President P.O. Box 308, Burgin, KY 40310
- Associate Vice‑Presidents:
- Charlie Bauer, Norridge, IL
- Cal Eitel, Florissant, MO
- William Kern, Redwood, IN
- Raymond Morris, (address partly illegible)
Notes from the first week of 1987:
- Winter flying: Many modelers fly in subfreezing weather; check fingering, dress warmly.
- New frequencies: Concerns about compatibility with older equipment. Old radios can often be modified to work on new frequencies (at a modest cost). For narrow‑band operation, many owners can adapt by changing pins; club coordination of frequencies may help.
- Preseason checks: Now is the time to inspect planes, repair covering, check hinges, clevises, props, wiring, switches, and cycle batteries.
- Photos and events: Bill Johnson sent a photo of a Sopwith Pup (Gary Bussell) that won Best‑of‑Show at Louisville Fly‑in and Byron's Fly‑in. Bill is CD for IMAA Festival 1987 in Converse, IN (June).
- Mall show equipment: Jim has a booth ready; clubs are encouraged to use it. Contact him for loan.
- Call for submissions: Send news, event reports, ideas, and photos for the column. The column space is limited; contributions help keep it fresh.
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Executive Council & Events
Notes from recent meetings and events (Pasadena, IMS show, and other items):
- Executive Council meeting in Pasadena: Productive session with presentations from the F3B Soaring team and other agenda items.
- IMS (International Model Show): Large manufacturer presence, indoor demonstrations, and swap meet. An important industry meeting addressed radio frequency issues.
- Radio equipment caution: Some out‑of‑the‑box units may not be on the stated frequency. Thorough preflight checks, including range checks, are essential. You generally get what you pay for — invest in quality equipment and proper checks.
- FCC/AMA frequency phasing: The AMA is working with a narrow window of FCC access to move the program forward. Supplier resistance could delay the process.
- 1987 AMA Nats (District IX): Lincoln, NE, July 11–19, 1987. Lincoln chosen for accessibility, excellent facilities, and better sites for Free Flight, Pattern, Control Line, and Helicopters. Volunteers needed; benefits include paid rooms or next year's AMA dues in some cases.
- AMA Marketing & FAA committees: New AMA Marketing Committee chaired by an appointed member; Don Lowe formed a three‑person FAA Committee (Don Lowe, John Worth, Dave Brown).
- Museum donations: Artifacts and donations being stored and prepared for shipment to Reston, VA.
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Trade Shows & Contests
- District IV: MARC Show in Timonium, MD is growing; attendees can get transmitters checked for proper operation. Show dates include 30–31 May, 1987.
- Soaring & Electric: Texas Soaring Conference and local electric clubs (e.g., Dallas Electric Aircraft Flyers) are active. MRC and Benton produce inexpensive molded‑foam electric and rubber‑powered models ideal for schools and parks.
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Publications & Sound Measurement
- RC Report (Huntsville, AL) publishes engine test reports with dBA levels measured at specific rpm/prop combinations; editor Gordon Banks uses FAI‑type measurements at three meters — a useful reference for sound comparison.
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Miscellany
- Founders and heritage: A nod to early model aviation pioneers such as Frank Zaic and others; historical books and interviews are valuable to the hobby's heritage.
- Voyager: Burt Rutan (an AMA member) designed the Voyager aircraft — his model and early competition roots in model aeronautics are noted with pride.
- Free Flight & shared sites: Reports from Nashville Free Flight Society and mixed‑discipline flying sites highlight the need for cooperation and courtesy among different flying styles.
- Staffing changes: Don Peck resigned as District 5 RC Contest Coordinator due to increased work commitments; volunteers requested to fill the role.
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Happy flying and soft landings!
Transcribed from original scans by AI. Minor OCR errors may remain.
