Statement of Work

Proposals with a statement of work are prepared in cooperation with the prospective client. The proposal will include cost and calendar schedule and will be based on estimated man-hours per task. DARcorporation's success as a leading provider of contractual technical services usually results in long-term partnerships that go far beyond the initial assignment.


A. Aircraft Preliminary Design

  1. Sizing of the airplane to a given mission specification. Definition of the following parameters: Take-off Weight, Empty Weight, Mission Fuel Weight, Take-off Power, Wing area and Maximum Lift Coefficients. Class I Drag.

  2. List of comparative airplanes with similar mission performance

  3. Overall Configuration Selection
    • Fuselage Layout
    • Propulsion System Integration
    • Class I Performance involving Stall Speed, Take-off distance, Climb, Max Cruise Speed, Maneuver/Turn and Landing distance.
    • Wing and Empennage Planform Parameters based on volume coefficients and Class I Performance Sizing.
    • Type and Size of High Lift Devices
    • Landing Gear Type
    • Class I Weight & Balance based on weight fractions
    • Preliminary arrangement drawings
    • Class I Stability & Control
    • Weights and L/D iterations

  4. Dimensioned Three-view Drawings

  5. Major Systems. General system arrangements and location in the airframe.

  6. Landing gear tires and struts sizing. Verification of landing gear disposition.

  7. Initial structural arrangement drawings

  8. V-n diagrams
B. Aircraft Design
  1. Class II (detailed) weight calculations with center of gravity locations and determination of the forward and the most aft center of gravity loading scenarios.

  2. Generation of the Center of Gravity envelope

  3. Engine inclination determination

  4. Calculation of hingemoment derivatives and coefficients for elevator, aileron and rudders. Elevator, rudder and aileron sizing, including horn balance and tabs.

  5. Lift versus angle of attack curves for power-off, power-on, clean, take-off and landing condition.

  6. Verify trimmed maximum lift coefficients for the defined flight conditions and flap size verification.

  7. Calculation of zero angle of attack pitching moment, lift coefficients and stability and control derivatives for the defined flight conditions at forward and aft center of gravity.

  8. Trim diagrams for the defined flight conditions to determine control surface sizes.

  9. Stick force, stick-force gradients and stick-force-per-g gradients for the defined flight conditions at aft and forward center of gravity. Determination on whether down-spring and/or bob-weight installation are required. Where necessary, design adjustments will be suggested. Lateral-Directional trim. Control forces will be calculated for different flight conditions for several different bank angles and sideslip angles. Control forces will be compared with applicable FAR regulations.

  10. Class II (detailed) drag calculations for several flight including power effects.

  11. Performance calculations for:
    • Cruise (maximum speed, range, endurance and payload-range diagram)
    • Climb (Rate of climb)
    • Take-off
    • Landing
    • Stall speed
    • Maneuver

  12. Dynamics:
    • Calculation of the moments of inertia of the airplane at three different weights.
    • Determination of the longitudinal and lateral-directional transfer functions of the airplane.
    • Calculation of the damping ratios, frequencies and time constants of the airplane, compare with FAR 23 requirements. This will determine short period, phugoid, spiral, roll and Dutch roll behavior. Where necessary, design adjustments will be suggested.

  13. Preliminary layout drawing for all essential airplane systems

  14. Preliminary manufacturing breakdown

  15. Maintenance and accessibility requirements

  16. Preliminary cost analysis
C. Aerodynamic Design & Analysis
  1. Computational Fluid Dynamics (CFD) analysis

  2. Flow Characteristics

  3. Lift and Drag

  4. Torque and Moment

  5. Pressure Distribution

  6. Shape Optimization
D. Detailed Loads Analysis
  1. Generate V-n diagrams and derive maneuver, gust and landing loads for critical flight conditions

  2. Generate landing gear loads, engine mount loads, ground loads and flight control system loads

  3. Generate fatigue load spectrum
E. Detailed Structural Design
  1. Perform Finite Element Analysis (FEA) on lifting surfaces and size the lifting surface substructures accordingly

  2. Perform FEA on control surfaces

  3. Perform FEA on the fuselage and size the fuselage substructures accordingly

  4. Perform FEA on the landing gear and size the substructures accordingly

  5. Perform FEA on the engine/firewall integration with the fuselage and size the substructures accordingly

    Perform FEA on the full-scale airplane to inspect component interactions and full-scale structural dynamic characteristics

  6. Perform aeroelasticity analysis against divergence and flutter on all lifting surfaces and control surfaces

  7. Perform fatigue and crack growth analysis
F. Detailed Systems Design
  1. Flight control system

  2. Fuel system

  3. Electric system and hydraulic system
G. Wind Tunnel Testing and Program Management

H. Prototype Manufacturing

I. Load Test and Modal Test Program
  1. Load test will verify the structural integrity with deformation and strains monitored

  2. Modal test or Ground Vibration Test (GVT) will verify the structural resonances
J. Flight Testing