Definitions for the Beginner
Altitude
Air density reduces with altitude. This is reflected in the constant number used in the thrust formula.
- Sea level: 0.000011127
- 1,000 ft: 0.000010806
- 2,000 ft: 0.000010490
- 3,000 ft: 0.000010182
- 4,000 ft: 0.000009881
- 5,000 ft: 0.000009581
- 6,000 ft: 0.000009301
Common abbreviations and terms
- ARF: Almost ready to fly.
- BHP: Brake horsepower.
- CID: Cubic inch displacement.
- mph: Miles per hour.
- PLF: Propeller Load Factor (diameter squared × pitch).
- PL: Power loading (ounces of model weight per cubic inch of displacement).
- rpm: Revolutions per minute.
- Stability: A model’s ability to return to level flight after a gust or when controls are centered.
- Torque: Turning force, measured in inch-ounces.
- Trim: Adjusting controls to achieve level flight.
- TWR: Thrust-to-weight ratio (expressed as a percentage).
Wing area
- Constant chord: chord × span (in inches).
- Tapered: (root chord + tip chord) × span ÷ 2.
Divide square inches by 144 to convert to square feet.
Wing loading
Ounces of model weight divided by the wing area in square feet. The result is ounces per square foot of area.
M.A. — A. G. Lennon
Transcribed from original scans by AI. Minor OCR errors may remain.
