SkyRanger Weight & Balance
B.4.1 Weighing procedures to obtain empty CG and gross weight CG.
The CG limits for the Sky Ranger are:
-Forward limit = 9 inches aft leading edge of wing
-Aft limit = 19 inches aft of leading edge of wing
It is important to know the location of the CG of your airplane as this property affects the airplanes flying qualities (handling characteristics). Your choice and location of items such as engine, gearbox, prop, starter & battery, gas, crew and luggage affect the CG location. In flight, the effect of being at an aft limit CG will be a sluggish aircraft that will not respond well to control inputs and the aircraft will not recover well from stalls. Both pitch and yaw responses will suffer. The pilot should NEVER find himself flying with this condition. Corrective actions to prevent an aft CG condition may include removing baggage and/or relocating equipment such as the aircraft battery to a more forward location.
Empty weight and CG are the starting point for calculating all fight loading conditions one might encounter while flying his Sky Ranger. One must add, pilot, passenger and baggage as appropriate. The location of each item within the aircraft (station number) must be either measured or estimated. Balance calculations are easily accomplished using computer spread sheets or can be done manually using the tables below and hand calculators:
CASE 1. Empty CG
Empty weight CG = weight of each wheel x their arm = total moment / by total weight = CG in inches aft of datum point.
De-fuel the airplane. Empty weight will include engine fluids.
Use scales to measure the weight on each main wheel and the nose wheel. When using one scale, be sure to maintain aircraft level condition by adjusting the height of remaining two wheels using wooden blocks.
Example;
Station Weight (lbs.) x Arm = Moment (inch lbs.)
Front wheel 178 -28” - 4,984
Main wheels 441 +28” 12,348
Total _619_ Divided into 7,364 = 11.90 inches aft LE
Case 2. W&B for flight loading conditions
After obtaining empty weight CG location, continue the equation by adding additional weight in passenger, fuel and luggage stations.
Use the following calculations and reference points for CG determination.
Datum reference point ………..Leading edge of wing (LE)
Front wheel arm …………….…-28 inches
Main wheel arm ………………+28 inches
Pilot arm …...…………….…...+20 inches
Passenger arm ………………...+20 inches
Fuel arm ………………………+42 inches
Luggage arm ………………….+45 inches (max 35 lbs)
Gross weight ………………….1,212 lbs.
CG limits ……….……………..9 inches to 19 inches from datum point
StationWeight (lbs.) xArm = Moment
Empty weight case 1 _ _case 1_
Pilot ______+20”______
Passenger______+20”______
Fuel______+42”______
Luggage ______+45”______
Total ______Divided into ______=inches aft (LE)
Each of the following aircraft loading weights and CGs should be calculated:
- pilot with minimal fuel and no baggage
-pilot and passenger with full fuel and no baggage
-pilot and passenger with full fuel and maximum baggage
A weight and balance should be carried in the aircraft at all times.
If gross weight should exceed the limits of 1,212 lbs, then corrective action must be taken to reduce the aircraft load.
If a CG calculation should indicate that the CG would be either forward of 9 inches or aft of 19 inches, corrective action must be taken by off loading baggage, etc. to move the CG inside these limits before flight.
For your safety and the safety of your passengers check the weight and balance of your aircraft before each flight. Keep the aircraft gross weight and center of gravity within prescribed limits.
If there is the slightest doubt about the loading, it will be advisable to calculate it by using actual weights and moment arms to determine that the aircraft is loaded within safe limits.
Definitions
arm (moment arm)—the horizontal distance in inches from the reference datum to the item. The algebraic sign is plus ( + ) If measured aft of the datum and minus ( - ) if measured forward of the datum;
center of gravity (c.g.)—the point about which an aircraft would balance if it were possible to suspend it at that point. It is the mass center of the aircraft or the theoretical point at which the entire weight of the aircraft is assumed to be concentrated;
center of gravity range—the distance between the forward and aft c.g. Limits;
datum line—an imaginary vertical plane or line from which all measurements of arm are taken. The datum is established by the manufacturer. After the datum is selected all moment arms and the c.g. range must be computed with reference to that point;
fuel load—the expendable part of the aircraft load. Fuel load includes only usable fuel and not the fuel required to fill the lines or that which remains trapped in the tank sumps;
moment—the product of the weight of an item multiplied by its arm. Moments are expressed in inch pound (in.-lb.);
mean aerodynamic chord (MAC)—the average distance from the leading edge to the trailing edge of the wing. The MAC is specified for the aircraft by determining the average chord of an imaginary wing which has tile same aerodynamic characteristics of the actual wing.
station—a location in the aircraft which is identified by a number designating its distance in inches from the datum. The datum is therefore identified, as zero and the station and arm are usually identical;
useful load—the weight of the pilot, copilot, passengers, baggage, usable fuel, and drainable oil;
empty weight—the airframe, engines, and all items of operating equipment that have fixed locations and are permanently installed in the aircraft. It includes optional and special equipment.
Poundskilograms
Left Main= 220 99.79
Rite Main= 235 106.59
Nose Gear= 14967.58
Empty Weight = 604273.96including the oil and the antifreeze
20 Galons Fuel= 12054.43
TOTAL= 724328.40