Aircraft scales, also known as aircraft weighing scales, are specialized devices used to accurately determine the weight of airplanes and helicopters.
Aircraft weight scales provide precise measurements of an aircraft’s weight in various configurations, including empty weight, operating weight, and maximum takeoff weight. This information is critical for safe flight operations for several key reasons.
The airplane’s center of gravity is a crucial point that affects its stability and control during flight. Aircraft weight scales help determine the center of gravity by measuring the weight distribution across the landing gear. An improper center of gravity can lead to control difficulties and potential accidents.
Optimizing Payload and Fuel Efficiency
Payload Management
Precise weight data allows aircraft operators to calculate the maximum allowable cargo, passengers, and fuel for each flight. This ensures that the airplane operates within its weight limitations, preventing overloading that can compromise safety and performance.
Fuel Efficiency
Excess weight directly translates to increased fuel consumption. Accurate weight data allows for optimizing fuel loading, minimizing unnecessary fuel burn, and reducing operational costs.
Types of Aircraft Weighing Scales
There are several main types of aircraft weight scales, each suited for different aircraft sizes and operational needs.
Platform Scales
Aircraft platform scales consist of large, flat platforms embedded with load cells – sensors that convert a mechanical force into a measurable electrical signal. The entire airplane taxis onto the platform, and the load cells measure the weight distribution across the landing gear, calculating the total weight of the aircraft.
Modern platform scales use high-precision load cells and sophisticated software to ensure accurate weight measurements within tight tolerances.
Platform scales can be designed with multiple weighing sections to accommodate various aircraft sizes. Some large airports might have platforms designed for different weight capacities, depending on the types of airplanes they service.
Top-of-jack
Top-of-jack scales are used when the airplane is already partially lifted off the ground using its designated jack points, which are locations on the fuselage designed for lifting during maintenance.
High-precision load cells are placed on top of the jacks at each jacking point. As the airplane’s weight rests on the jacks and the load cells, the weight distribution is measured. The system calculates the total weight of the aircraft based on the readings from each load cell.
Jack adapters – specially designed attachments that fit on top of the existing airplane jacks – provide a stable platform for the load cells. Some jacks might have built-in mounting provisions for the load cells, eliminating the need for these adapters.
A digital display unit shows the weight data from each load cell and calculates the total weight of the aircraft. In some systems, the data might be transmitted wirelessly to the indicator for increased safety and convenience.
Under-Axle Weighing Systems
With under-axle weighing systems, hydraulic axle jacks are positioned at each of the aircraft’s designated jacking points. Load cells integrated into the jacks measure the weight on each axle, and the system then calculates the total aircraft weight.
These systems can be used to quickly and accurately weigh aircraft of all sizes, including large commercial airliners like the Boeing 737 or Airbus A320.
Proper distribution of weight plays a large and important role in an aircraft’s overall performance. Load your airplane improperly, and it will affect its fuel consumption, speed, rate of climb, controllability, ceiling, and even structural integrity.
When building your own airplane, determining its weight and balance before its first flight is critical to your safety—and the safety of those who will fly with you. Take care and all the time necessary to determine accurate weight and balance numbers.
Like production aircraft, homebuilts must have accurate weight and balance data when they are certificated, and when the FAA examines your completed project, the inspector will want to see your weight and balance paperwork.
Most kit manufacturers and aircraft designers offer some weight and balance assistance by providing the airplane’s maximum gross weight, aerobatic gross weight (if applicable), maximum baggage weight for each compartment, the forward and aft center of gravity (CG) limits, the aerobatic CG range, and the datum reference point. It is your responsibility to weigh and calculate the numbers for your airplane.
Several designers also provide tables with sample weight and balance numbers showing typical loading situations. These are for your review only. Do not use them for your aircraft because the weight and balance numbers are different for every airplane, even if they are of the same make and model.
Just how deep must you get into weight and balance? Deep enough to tabulate the weight and balance data needed to get your airworthiness certificate—and to properly load your aircraft. As the pilot in command, Federal Aviation Regulation 91.7, Civil Aircraft Airworthiness, makes you responsible for determining whether your aircraft is safe to fly.
Part of your determination of an aircraft’s suitability for safe flight is making sure it is within its weight and balance limits and it does not exceed its maximum gross weight. You can’t determine that without calculating your airplane’s weight and balance numbers. Your aircraft’s weight and balance also plays a huge role in how safely it flies.
Performance & Safety
What effects can weight and balance have on an aircraft? If an airplane is heavier than its maximum gross weight, the airplane’s…
• takeoff run will be longer because the takeoff speed will be higher.
• rate and angle of climb performance will be reduced.
• loading during aerobatic flight will be excessive.
• cruising speed will be reduced.
• cruising range will be shortened.
• service ceiling will be lowered.
• maneuverability will be decreased.
• landing roll will be longer because the landing speed will be higher.
In conclusion, Accurate aircraft weight is paramount for flight operations, it directly impacts performance, stability, and controllability.
Sources: PILOT.COM