Edition: Model Aviation - 1994/12
Page Numbers: 167, 168
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AMA News

Sound & Model Aeronautics

Howard Crispin, Jr.

Bisson Mufflers: Jim Bisson has been a well-known source of mufflers for a number of years in Canada. He has not been especially noticed on this side of the border, and that is something being remedied. His line of mufflers is being imported by Gerard Enterprises, Inc., W226 N825 Eastmount Drive, Waukesha, WI 53186. Jim Gerard is also the present importer of the Moki line of engines.

I obtained some mufflers from Jim Bisson and have made runs with two of the units. If other items in what is becoming a very extensive line are as efficient as those tested, modelers in the United States will have another good product available for sound level reduction.

The figures provided were from bench runs with a specific propeller. Your particular results may vary based on several factors. The propeller you choose may not be as quiet on the ground as the one I used, or it may be quieter. Whichever way it goes with your assembly, the measured level could be different.

Another very important factor is vibration. If your aircraft has a plastic or fiberglass fuselage and tightly stretched plastic covering on the wing and stabilizer, you can get noise due to vibration. This can be sufficient to affect the readings. You should use vibration isolators on every engine installation for this and other reasons.

The mufflers tested were one for a .61 cubic inch engine and one made for the SuperTigre 3000. The one used on the .61 will bolt directly to the O.S. .61SF, as shown in photo number one. It will fit the Moki and probably others with an adapter plate that also extends the exhaust stack about one-quarter inch. The one for the ST 3000 bolts directly to the engine and is similar in appearance except for size.

Also available are the so-called Pitts-style mufflers. Workmanship is very neat, and they appear to be well constructed. The O.S. .61SF was run with an APC 12 x 8 propeller, and the sound level was checked at two speeds. Measurements were made at nine feet using a Simpson sound meter, with calibration checked prior to the runs.

  • Sound level at 10,000 rpm: 84 dBA
  • Sound level at 11,000 rpm: just under 97 dBA

Again, your results will depend on what and how you operate. These are very good figures. I did not have the opportunity to check other propeller combinations. The fuel used was 10 percent nitro with lubricant containing some castor oil. The ST 3000 was run with a Zinger 18 x 8 propeller; I do not have bench-run numbers for it, so you may operate at higher speeds than these. I would not expect the results to be very different, since these were not especially rich runs.

The fuel used for the Tigres was Bob Davis Nitrotane for four-stroke engines. It seems to perform very well in the big Tigres. The results on this compare to only one other muffler I have tested on the ST 3000, the kidney-shaped one sold by Eric Dern, Quality RC Products.

  • At 7,000 rpm (ST 3000 with kidney-shaped muffler): 84 dBA
  • O.S. .61SF operation at 7,800 rpm: 86.5 dBA

Again, these will vary with the installation. If you are interested in any special application you would like manufactured in the way of mufflers, contact Jim Bisson at Bisson Custom Mufflers, R.R. #1, Taits Island #32, Parry Sound, Ontario P2A 2W7.

Fuel System

The Cline Proportional Control Fuel System was mentioned in an earlier article. Since then I took some pictures of the components. Photo number two shows all of the parts provided.

  • Item 1: Controller — the largest part, about one inch square and about 3/8-inch thick.
  • Item 2: High-frequency check valve — the heart of the operation.
  • Item 3: Angle connectors for the inlet and outlet of the controller.
  • Item 4: Tubing plugs (vent and fill lines).
  • Item 5: Two tee fittings that provide the connection of the vent and fill lines.

You will need to provide your own 1/32 inch I.D. fuel tubing and your favorite fuel filter (goes between the tank and the controller).

The purpose of the system is to provide a constant pressure, proportional to rpm and fuel flow, at all times. This guarantees steady power at all attitudes and conditions. It should be especially useful for those performing aerobatics and for scale applications where transitions to lean mixtures are a major problem on vertical maneuvers.

Contact Cline and Associates at 807 Alpha Road, Box 44, Alpha, OH 45301 for details on the use of the system.

Audited Financial Statement 1993

This statement was received from the auditors by AMA Headquarters on July 25, 1994.

The Academy of Model Aeronautics, Inc. — Balance Sheet

As of December 31, 1993

ASSETS

UNRESTRICTED FUNDS

Current Assets:

  • Cash and cash equivalents — $1,871,386
  • Receivables — $173,005
  • Inventory (at cost) — $99,980
  • Prepaid insurance — $100,796
  • Prepaid membership costs — $147,941
  • Prepaid expenses — $37,354
  • Total Current Assets — $2,430,462
  • Investments — $2,495,819
  • Property and equipment (at cost, net of accumulated depreciation) — $5,803,505
  • Other assets — $33,730

RESTRICTED FUNDS

  • Cash — $55,822
  • Due from unrestricted funds — $138,280
  • Total Restricted Funds — $194,102

The Academy of Model Aeronautics, Inc. — Statement of Revenue, Expenses and Changes in Unrestricted Fund Balances

Year Ended December 31, 1993

REVENUE

  • Membership — $5,718,776
  • Museum patron program — $21,239
  • Club charter fees — $84,282
  • Event sanctions and insurance — $30,447
  • Supply and souvenir sales — $100,041
  • Model Aviation advertising — $739,606
  • Model Aviation subscriptions — $96,521
  • Total Revenue — $6,830,972

EXPENSES

  • Operating expenses — $4,786,331
  • Model Aviation magazine direct costs — $1,731,335
  • Supply and souvenir costs — $120,107
  • Depreciation and amortization — $124,169
  • Office services including managers — $120,765
  • Committees — $31,005
  • National Championship contest — $28,266
  • Total Expenses — $6,992,270
  • Excess of expenses over revenues from operations — $(161,298)

OTHER REVENUE (EXPENSES)

  • Interest income — $218,230
  • Contributions — $15,492
  • Fund raising revenue — $18,020
  • Miscellaneous income — $6,820
  • Interest expense — $(155,651)
  • Investment income taxes — $(6,771)
  • Loss on sale of assets — $(12,063)
  • Federal and state income tax — $(84,000)
  • Total other revenue (expenses) — $(31,713)
  • Excess of expenses over revenues — $(193,011)
  • Unrestricted fund balances, beginning of year — $5,266,787
  • Fund transfers and appropriations — $356,519
  • Unrestricted fund balances, end of year — $5,427,295

Note: Copies of the complete audited financial statements are available for $5 upon written request. Audit performed by Brady, Ware, and Schoenfeld, Inc.

The Academy of Model Aeronautics, Inc. — Liabilities and Fund Balances

UNRESTRICTED FUNDS

Current Liabilities:

  • Accounts payable — $141,303
  • Current maturities of mortgages, notes payable and capital lease obligations — $80,300
  • Accrued expenses — $169,343
  • Deferred membership revenue — $334,856
  • Interest payable — $11,357
  • Total Current Liabilities — $737,159
  • Deferred membership revenue — $172,800

Long-Term Liabilities:

  • Mortgages and notes payable — net — $1,423,500
  • Obligation under capital lease — net of current maturities — $27,579
  • Line of credit — $10,000
  • Security deposit — $1,461,088
  • Total Liabilities — $5,542,496

UNRESTRICTED FUND BALANCES

  • Operating fund — $1,332,021
  • Designated by Executive Council for contingencies — $3,940,000
  • Total Unrestricted Fund Balances — $5,272,021

RESTRICTED FUNDS

  • Fund balances — $194,102

The Academy of Model Aeronautics, Inc. — Statement of Cash Flows

Year Ended December 31, 1993

OPERATING ACTIVITIES

  • Excess (deficiency) of revenue over expenses — $(93,285)

Adjustments to reconcile net cash provided (used) by operations:

  • Depreciation and amortization — $200,185
  • Gain on disposals of equipment — $(71,004)
  • Loss on disposals of equipment — $78,004

Changes in operating assets and liabilities:

  • Receivables and inventories — $(33,305)
  • Prepaid expenses — $9,680
  • Inventory and payables — $64,700
  • Accounts payable and accrued expenses — $(24,773)
  • Deferred membership revenue — $455,433
  • Deposits — $(14,031)
  • Net Cash Provided (Used) by Operating Activities — $(324,355)

INVESTING ACTIVITIES

  • Purchase of property and equipment — $(327,825)
  • Proceeds from sale of property and equipment — $3,700
  • Purchases of investments — $(339,498)
  • Proceeds from sale of investments — $339,498
  • Net Cash Used (Provided) by Investing Activities — $(327,125)

FINANCING ACTIVITIES

  • Payments on long-term liabilities — $(69,544)

NET INCREASE (DECREASE) IN CASH AND CASH EQUIVALENTS

  • $(713,553)
  • Cash and cash equivalents, beginning of year — $2,584,939
  • Cash and cash equivalents, end of year — $1,871,386

SUPPLEMENTAL CASH FLOW INFORMATION

  • Interest paid — $108,066
  • Noncash capital purchases financed through capital leases — $55,000

The Academy of Model Aeronautics, Inc. — Statement of Revenue, Expenses and Changes in Restricted Fund Balances

Year Ended December 31, 1993

(Note: A table of restricted funds revenue, expenses, excess (deficiency) of revenue over expenses, fund balances beginning, appropriations and transfers, and fund balances end of year follows in the statement.)

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