Airplane Preliminary Design

Course Outline

Day One

• Review of drag polar breakdown for subsonic and supersonic airplanes, rapid method for drag polar prediction, check of drag polar realism; review of fundamentals of flight mechanics: take-off and landing characteristics, range, endurance and maneuvering, the payload-range diagram; preliminary sizing of airplane take-off weight, empty weight and fuel weight for a given mission specification: applications; sensitivity of take-off weight to changes in payload, empty weight, range, endurance, lift-to-drag ratio, and specific fuel consumption; role of sensitivity analyses in directing program-oriented research and development: applications; performance constraint analyses: relation between wing loading and thrust-to-weight ratio (or wing loading and weight-to-power ratio) for the following cases: stall speed, take-off field length and landing field length, statistical method for estimating preliminary drag polars, review and effect of airworthiness regulations

Day Two

• Continuation of performance constraint analyses: relation between wing loading and thrust-to-weight ratio (or wing loading and weight-to-power ratio) for the following cases: climb and climb rate (AEO and OEI), cruise speed, and maneuvering; the matching of all performance constraints and preliminary selection of wing area and thrust required: applications; preliminary configuration selection; what drives unique (advanced) configurations? Discussion of conventional, canard and three-surface configurations; fundamentals of configuration design, step-by-step analysis of the feasibility of configurations: applications; fundamentals of fuselage and wing layout design; aerodynamic, structural and manufacturing considerations; effect of airworthiness regulations; high-lift and lateral control design considerations; handling quality requirements; icing effects; layout design of horizontal tail, vertical tail and/or canard; static stability and control considerations; the X-plot and the trim diagram; stable and unstable pitch breaks; effect of control power nonlinearities; icing effects

Day Three

• Fundamentals of powerplant integration: inlet sizing, nozzle configuration, clearance envelopes, installation considerations, accessibility considerations, maintenance considerations; effect of engine location on weight, stability and control; minimum control speed considerations; fundamentals of landing gear layout design; tip-over criteria; FOD considerations; retraction kinematics and retraction volume; take-off rotation; Class I weight and balance prediction; the c.g. excursion diagram; Class I moment of inertia prediction; importance of establishing control over weight; preliminary structural arrangement for metallic and composite airframes; manufacturing and materials considerations; the V-n diagram; Class II weight, balance and moment of inertia prediction; fundamentals of static longitudinal stability; the trim diagram, trim considerations for conventional, canard and three-surface designs, tail and canard stall

Day Four

• Continuation of fundamentals of static longitudinal stability; deep stall and how to design for recoverability, effects of the flight control system; control force versus speed and load factor gradients; flying quality considerations; additional stability and control considerations; effect of flaps; minimum control speed with asymmetric thrust; take-off rotation and the effect of landing gear location; review of dynamic stability concepts and prediction methods; short period, phugoid, spiral roll and Dutch roll modes; flying quality criteria: before and after failures in flight crucial systems; the role and limitations of stability augmentation; review of control surface sizing criteria: trim, maneuvering and stability augmentation; initial system gain determination; sensitivity analyses and their use in early design decision making; flight control system layout and design considerations; mechanical and hydraulically powered flight controls; layout design considerations for redundant "flight-crucial" systems: architectures associated with various types; safety and survivability considerations; the airworthiness code; fundamental considerations in fuel system layout design; sizing criteria; some do’s and don’ts; layout and design considerations for "other" systems: de-icing, water and waste water

Day Five

• Landing gear design revisited, shock absorber design, structural integration of the landing gear, some do’s and don’ts; factors to be considered in estimation of: research and development cost and manufacturing and operating cost; the concept of airplane life cycle cost: does it matter in commercial programs? Discussion of 81 rules for "design for low cost"; the break-even point, estimation of airplane "net worth" and its effect on program decision making; other factors in airplane program decision making, finding a market niche, risk reduction through technology validation, design to cost; lessons learned in past programs: do we really learn them?