PA -18 Weight and Balance
Piper PA-18 Super Cub · Weight And Balance
Overview
This document provides essential information regarding the weight and balance calculations for the Piper PA-18 Super Cub. It outlines key definitions related to weight, useful load, maximum gross weight, center of gravity (CG), and the datum point used for measurements. The document emphasizes the importance of accurate weight and balance calculations for safe aircraft operation, particularly due to the unique reference points used by Piper. It includes an example calculation to illustrate how to determine the adjusted CG based on the aircraft's weight and moment. This guide is intended for pilots and aviation enthusiasts who need to understand the specifics of weight and balance for the PA-18 Super Cub.
- Empty Weight includes engine oil and unusable fuel.
- Maximum Gross Weight for the PA-18 Super Cub is 1760 lbs.
- Datum is located 60 inches ahead of the wing leading edge.
- CG limits for floats at max gross weight are 14.0 to 20.0 inches aft of the wing leading edge.
- To find the adjusted CG, subtract 60 inches from the unadjusted CG.
Document
Source
Originally published by alaskafloatratings.com. Sprinkle hosts a reference copy with an added summary, specifications and searchable full text.
Document details
- Type
- Weight And Balance
- Pages
- 2
- File size
- 136 KB
- Publisher
- alaskafloatratings.com
Specifications & performance
Extracted from this document.
Specifications
- Empty weight (lb)
- 1,405
- Max takeoff weight (lb)
- 1,760
Weight & balance
- Cg range (in)
- 14
- Max takeoff weight (lb)
- 1,760
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In this document
Key Definitions
This section defines essential terms related to weight and balance calculations, including Empty Weight, Useful Load, Maximum Gross Weight, Center of Gravity (CG), and Datum. Understanding these terms is crucial for accurate weight and balance assessments.
Weight & Balance Calculation
This section explains the calculations involved in determining the weight and balance of the PA-18 Super Cub. It details how to calculate the Moment by multiplying Weight and Arm, and how to find the CG by dividing the total Moments by the total Weight.
PA-18 Weight & Balance Specifics
This section provides specific details about the PA-18 Super Cub's weight and balance, including the location of the Datum, which is 60 inches ahead of the wing leading edge. It also explains how to adjust the CG based on this reference point.
Example Calculation
An example calculation is provided to demonstrate how to determine the adjusted CG for a specific aircraft. It shows the formula used and provides a sample scenario to clarify the process.
Quick Rule of Thumb
A practical tip is offered for pilots: if in doubt about weight distribution, it is advisable to move weight forward and lighten the load to ensure safe operation.
Safety notes
- A heavy tail can lead to dangerous flight conditions; always check weight distribution.
Full document text
PA -18 Weight and Balance Note: PA-18 Weight and Balance calculations can be tricky due to Piper’s reference to the aircraft datum. Below, refresh your memory with the following basic terms and learn more about PA-18 calculations. Key Definitions Empty Weight – The weight of the airplane as built, including engine oil and unusable fuel. Useful Load – The difference between the max takeoff weight and empty weight. It includes fuel, passengers, cargo, and baggage. Maximum Gross Weight – The heaviest weight an aircraft is allowed to be for safe operation. Center of Gravity (CG) – The point where the aircraft would balance if it were suspended in the air. Weight & Balance Calculation Weight – The amount, in pounds, that an object weighs. Arm – The distance, in inches, from a fixed reference point (called the Datum). Moment – A measure of how weight is distributed along the aircraft. This is the product of multiplying Weight x Arm = Moment. Datum – Is the point in space that the measurements for the Arms are located. It can be located wherever the manufacturer decides. The Total of all Moments added together, Divided by the total Weight = CG (Center of Gravity). PA-18 Weight & Balance When designing the Super Cub (PA-18), Piper decided to place the Datum 60” (inches) ahead of the “Wing Leading Edge”. Then to add confusion, the CG limits are in relation to the Wing Leading Edge. Example: For aircraft N7862P (below), the CG range on floats at max gross weight of 1760 lbs. is 14.0 inches to 20.0 inches aft of the wing leading edge, but the datum is 60.0 inches ahead of the wing leading edge. To determine the correct CG, this requires the pilot to complete the W&B calculation, then they must subtract the 60.0 inches from that number to determine the accurate adjusted CG. *Moment / Weight = unadjusted CG - 60.0 = adjusted CG Example from the below W&B form: 105837.4 / 1405 = 75.33 – 60.0 = CG of 15.33 Quick Rule of Thumb | "If in doubt, move weight forward and lighten the load. A heavy tail is a deadly fail."