RFP compliance
Report each requirement by name and distinguish threshold, objective, and predicted capability.
AE481 · Lesson 9
Performance
Describe what an aircraft can do—and show where requirements, energy, and maneuver limits shape the design.
Performance turns design predictions into evidence
A credible performance story connects requirements to mission outcomes and explains the aircraft’s energy and maneuver capability.
Mission performance
Show fuel burns and range–payload–loiter tradeoffs across the mission.
Maneuverability
Use specific excess power (Ps), E–M diagrams, V–n limits, and corner velocity to explain agility.
Make RFP compliance unmistakable
Use color to communicate the result, but retain the numbers so the reader can verify the margin.
| Design requirement | Threshold | Objective | Predicted capability |
|---|---|---|---|
| Per-unit cost | $50M | $35M | $55M |
| Mission radius | 1,750 nm | 2,250 nm | 1,825 nm |
| Runway length | 10,000 ft | 8,000 ft | 7,500 ft |
| Maximum speed | Mach 1.6 | Mach 2.1 | Mach 1.59 |
Mission fuel burns expose the expensive segments
Change the reserve and loiter assumptions to see how fuel allocation—and the remaining design margin—shift.
Range and loiter compete for the same fuel
The feasible combinations lie below a concept’s trade line. A point can satisfy either requirement alone and still miss the combined mission.
Specific excess power (Ps) shows where energy is available
Positive Ps can become climb or acceleration. The zero contour marks the sustained-performance boundary.
Streak Eagle converted excess power into record climbs
The record profile alternated acceleration, pull-up, and climb segments instead of following one constant condition.
Rate and Radius - Level turn performance
For a coordinated level turn, the same speed and load factor determine both how quickly and how tightly the aircraft turns.
Coordinated level turn
Corner velocity is where lift and structural limits meet
The V–n diagram combines aerodynamic stall boundaries with positive and negative structural load limits to define the maneuver envelope.
Energy–maneuverability (E–M) diagram
At constant altitude, turn-rate, turn-radius, load-factor, and specific-excess-power boundaries reveal where the aircraft can sustain or trade energy during a maneuver.
For this notional constant-altitude case: Mach at minimum turn radius < Mach at maximum turn rate < Mach at maximum load factor.
F-16 E–M Dogfight: Energy Trade Through a Two-Circle Fight
Two identical F-16s merge on reciprocal headings and pull 9 g. Before their descending corner turns carry them past one another, they point nose-to-nose, unload to 1 g, accelerate, re-merge, and resume the 9-g descent. At 500 ft MSL, Blue uses a minimum-radius turn to bring its nose onto Red.
PhaseMerge
Airspeed540 kt
Altitude15,000 ft
Load factor9.0 g
Turn rate—
Specific excess power—
Notional teaching model: each aircraft now takes corner speed, turn rate, acceleration, descent rate, and sustained performance from its own altitude-dependent E–M envelope and limits. The max-g entry converts negative Ps into level-flight deceleration until corner speed; transitions from corner to best sustained rate and to Blue’s unsustained minimum-radius boundary remain discrete. Blue then decelerates along the lift-limited boundary until reaching the 1-g level-flight stall. Ps contours run from −1,000 to +500 ft/s in 250-ft/s increments. Dashed gray radius contours are fixed kinematic references—altitude moves the performance envelopes, not the radius lines. The engagement stops when either aircraft records its third valid nose-on PEW.
F-15A/F-16C Turn Performance Comparison
At 10,000 ft, the overlaid turn-rate envelopes show how configuration, weight, and energy limits shape the two fighters' maneuver performance.
F-15F-16Aircraft purpose reshapes the maneuver envelope
Thrust loading and wing loading help explain why a fighter and a bomber occupy very different performance spaces.
| Metric | F-15C | B-52H |
|---|---|---|
| Sea-level thrust | 48,000 lb | 68,000 lb |
| Takeoff weight | 42,650 lb | 225,000 lb |
| Wing area | 608 ft² | 4,000 ft² |
| TSL/WTO | 1.14 | 0.30 |
| WTO/S | 69.1 psf | 56 psf |
The fighter’s high thrust loading supports rapid energy addition; the bomber’s design prioritizes payload, endurance, and efficient cruise.