PA 28-181 Weight and Balance Calculator
Professional Flight Planning Tool for Piper Archer II
1. Aircraft Basic Empty Weight
Enter the weight from your aircraft's specific POH/Weight & Balance sheet.
The center of gravity location of the empty aircraft.
2. Loading Configuration
Arm: 80.5 inches
Arm: 118.1 inches
Arm: 142.8 inches (Max 200 lbs)
Arm: 95.0 inches (6 lbs/gal)
Center of Gravity (CG)
—
Calculating…
Total Gross Weight
— lbs
Total Moment
— in-lbs
Useful Load Remaining
— lbs
Loading Table
| Item | Weight (lbs) | Arm (in) | Moment (in-lbs) |
|---|
CG Envelope Graph
Graph shows Normal Category Limits for PA-28-181.
What is a PA 28-181 Weight and Balance Calculator?
A PA 28-181 weight and balance calculator is a critical flight planning tool designed specifically for the Piper Archer II aircraft. In aviation, "weight and balance" refers to the determination of the aircraft's total mass and the location of its center of gravity (CG). For the Piper PA-28-181, adhering to these limits is not just a regulatory requirement but a fundamental safety necessity.
This calculator helps pilots ensure that their aircraft is loaded within the specific "envelope" defined by the manufacturer. The Piper Archer II has a maximum takeoff weight of 2,550 lbs and a specific range where the center of gravity must reside. If the CG is too far forward, the aircraft may be difficult to rotate for takeoff or flare for landing. If it is too far aft, the aircraft becomes unstable and may be impossible to recover from a stall.
Pilots, student pilots, and flight instructors use this tool before every flight to verify that passengers, baggage, and fuel loads do not compromise the aircraft's airworthiness.
PA 28-181 Formula and Mathematical Explanation
The core physics behind the PA 28-181 weight and balance calculator relies on the principle of moments. A "moment" is a rotational force, calculated by multiplying a weight by its distance from a reference point (datum).
The formula used is:
Moment = Weight × Arm
Center of Gravity (CG) = Total Moment ÷ Total Weight
Variable Definitions
| Variable | Meaning | Unit | Typical PA-28-181 Value |
|---|---|---|---|
| Weight | Mass of the item (passenger, fuel, etc.) | lbs | Varies |
| Arm | Distance from the reference datum | inches | 80.5″ (Front Seats) |
| Moment | Rotational force (Weight × Arm) | in-lbs | Calculated |
| Datum | Imaginary vertical plane (Reference 0) | N/A | 78.4″ ahead of wing leading edge |
Practical Examples (Real-World Use Cases)
Example 1: The Cross-Country Trip
A pilot and a passenger are flying a Piper Archer II with full fuel and baggage.
- Basic Empty Weight: 1,600 lbs @ 87.5″
- Front Occupants: 380 lbs (Two adults)
- Rear Occupants: 0 lbs
- Fuel: 48 gallons (288 lbs)
- Baggage: 50 lbs
Result: The total weight is 2,318 lbs, which is under the 2,550 lbs limit. The calculated CG is typically well within the envelope, ensuring a stable and safe cruise.
Example 2: Heavy Load Training Flight
An instructor and student are flying with a heavy observer in the back seat.
- Basic Empty Weight: 1,600 lbs @ 87.5″
- Front Occupants: 400 lbs
- Rear Occupants: 220 lbs
- Fuel: 30 gallons (180 lbs) to save weight
- Baggage: 0 lbs
Result: Total weight is 2,400 lbs. However, the heavy rear passenger shifts the CG aft. The PA 28-181 weight and balance calculator will verify if this aft CG is still within the 93.0-inch limit. If it exceeds 93.0 inches, the flight is dangerous and illegal.
How to Use This PA 28-181 Weight and Balance Calculator
- Enter Aircraft Data: Input the Basic Empty Weight and Arm found in your specific aircraft's POH (Section 6). Every airplane is unique.
- Input Loading: Enter the weights for the pilot, front passenger, rear passengers, and baggage.
- Add Fuel: Enter the fuel in gallons. The calculator automatically converts this to pounds (6 lbs/gal).
- Review Results: Check the "Status" indicator. It must be green (Within Limits).
- Check the Graph: Look at the blue dot on the CG Envelope graph. It must fall inside the polygon boundaries.
Key Factors That Affect PA 28-181 Results
Several factors influence the outcome of your weight and balance calculation:
- Fuel Burn: As you fly, you burn fuel. Since the fuel tank arm (95.0″) is often different from the aircraft's CG, burning fuel shifts the CG. Always check your landing weight and balance as well.
- Baggage Placement: The baggage area in a PA-28-181 has a long arm (142.8″). Even a small amount of weight here has a large leverage effect (moment), moving the CG aft significantly.
- Passenger Weight Accuracy: Guessing weights is dangerous. In winter, heavy clothing adds significant weight. Always estimate conservatively or use a scale.
- Aircraft Modifications: New avionics or equipment changes the Basic Empty Weight. Ensure you are using the most current weight and balance sheet for the aircraft.
- Density Altitude: While not part of the W&B formula directly, a heavy aircraft performs poorly in high density altitude. Being at max gross weight on a hot day may prevent a safe climb.
- Zero Fuel Weight: Ensure that the aircraft remains within CG limits even if all fuel is consumed (though you should never run out of fuel!).
Frequently Asked Questions (FAQ)
What is the maximum gross weight for a PA-28-181?
The standard maximum takeoff weight (MTOW) for a Piper Archer II (PA-28-181) is 2,550 lbs. The ramp weight is typically 2,558 lbs to allow for fuel burn during taxi.
What happens if the CG is too far aft?
An aft CG makes the aircraft unstable. Pitch control becomes overly sensitive, and stall recovery may become impossible because the elevator lacks the authority to push the nose down.
Does this calculator work for the Piper Warrior (PA-28-161)?
No. While similar, the Warrior has different weight limits and moment arms. You must use a calculator specifically calibrated for the PA-28-161.
How much does AvGas weigh?
Standard aviation gasoline (100LL) weighs approximately 6 pounds per gallon. This calculator uses that standard conversion.
Where is the datum line on a PA-28-181?
The reference datum is located 78.4 inches forward of the wing leading edge at the intersection of the straight and tapered sections.
Can I put 200 lbs in the baggage compartment?
Yes, the structural limit for the baggage area is 200 lbs, provided the aircraft remains under Max Gross Weight and within CG limits.
Why does the CG envelope narrow at lower weights?
Actually, in the PA-28-181, the envelope narrows at the forward limit as weight increases. At 2,550 lbs, the forward limit is 88.6″, whereas at 2,050 lbs, it is 82.0″. This ensures adequate elevator authority at heavier weights.
Is this calculator legal for flight?
This tool is for educational and planning purposes. The Pilot in Command (PIC) must always verify calculations against the official Pilot Operating Handbook (POH) for the specific aircraft being flown.
Related Tools and Resources
- Density Altitude Calculator – Determine aircraft performance based on temperature and pressure.
- Crosswind Component Calculator – Calculate safe takeoff and landing wind limits.
- Piper PA-28 Technical Specifications – Detailed specs for Archer, Warrior, and Arrow models.
- Aviation Fuel Planning Tool – Calculate endurance and range for your flight.
- Stall Speed Charts – Understand how weight affects stall speeds.
- Rate of Descent Calculator – Plan your approach and arrival profiles.