Reflections of an Aerospace Engineer

Introduction to Aircraft Performance and Mission Analysis Part 5 – Example Calculations by John Golan

© John Golan 2015

Material derived from openly published sources No technical data subject to the EAR or ITAR

Performance & Mission Analysis: Essentials Completing a calculation requires knowledge of: • Aircraft size and configuration – – – –

Wing area Empty weight Fuel weight Payload

• Engine thrust and fuel consumption – Requires both part power and max/military thrust and fuel consumption

• Drag polar, including effects of: – External stores drag – Mach number effects – g-load effects

2

Modeling Engine Performance • Data is often available in the open literature for static sea level engine performance – – – –

Maximum and military (dry) thrust Specific fuel consumption Overall pressure ratio (OPR) Bypass ratio

• Basic performance metrics can be projected analytically for other operating conditions – Don’t need to know how the engine meets its operability objectives, just assume that it does – Will not know about “keep out” zones or limits due to flutter, P3 or other criteria

3

Modeling Engine Performance Two off-the-shelf software packages exist for projecting engine operation: • AEDsys – Published by AIAA as a supplement to their engine design textbook – Intended as a teaching tool – Offers relatively simple modeling capability of limited fidelity

• GasTurb – Produced by a retired engineer from MTU – More comprehensive than AEDsys, but more difficult to use

For the simulations described here, AEDsys was used 4

Example of Literature Data: F100-PW-220 • Published values from the literature: – – – – –

Fan Pressure Ratio Overall Pressure Ratio Bypass Ratio Burner Exit Temperature, T4 Max Afterburning Thrust  Air Flow  Thrust Specific Fuel Consumption  Turbine Exit Gas Temperature

– Military Thrust  Thrust Specific Fuel Consumption

3.12 24.9 0.63 2565 ºF 23,840 lb 228.0 lb/s 2.170 lb/lb/h 1710 ºF

14,670 lb 0.710 lb/lb/h

• Assumptions need to be made for: – Component efficiencies – T7 (afterburner) temperature – Turbine cooling air and leakages Sources: Gething, Modern Fighting Aircraft: F-15, p. 22. Jane’s All the World’s Aircraft 1988-89, p. 733 The History of Aircraft Gas Turbine Engine Development in the United States, p. 432 Mattingly, et al, Aircraft Engine Design, p. 303 5

Approximate Data-Match: F100-PW-220 • Comparisons can be drawn between the simple datamatch described here, and published performance tables for the F100-220 under NASA-TP-1538

• A data-match such as this should be sufficient for many initial performance calculations 6

Example of Literature Data: F110-GE-100 • Published values from the literature: – – – –

Fan Pressure Ratio Overall Pressure Ratio Bypass Ratio Max Afterburning Thrust  Air Flow  Thrust Specific Fuel Consumption

– Military Thrust  Air Flow  Thrust Specific Fuel Consumption

3.31 31.2 0.87 28,000 lb 263.3 lb/s 2.063 lb/lb/h

16,760 lb 263.3 lb/s 0.675 lb/lb/h

• Assumptions made for: – Component efficiencies – T4 (burner) and T7 (afterburner) temperatures – Turbine cooling air and leakages

Sources: Jane’s All the World’s Aircraft 1988-89, p. 723 The History of Aircraft Gas Turbine Engine Development in the United States, p. 448 7

Mission Profile Approximation: F-16C Block 40 • Basic Statistics from the literature: – – – – – –

Empty Weight Internal Fuel Weight External Fuel Weight Wing Span Wing Reference Area F110-GE-100 engine

19,100 6,972 6,760 31.0 300

lb lb lb ft sq ft

• Aerodynamic quantities: – Angle-of-attack limitations for the F-16 (as executed by the fly-by-wire control system) are described in NASA-TP1538 – Drag coefficients and aerodynamic efficiency for the F-16 are described in NASA-TP-3414 (shown) – Data for stores drag obtained from: Raymer, Aircraft Design: A Conceptual Approach 8

Mission Profile Analysis: F-16C Block 40 • Hi-Lo-Hi mission profile was assessed analytically – Mission profile definition obtained from: Fixed Wing Performance, USNTPS-FTM-No. 108 – Results iterated to confirm maximum combat radius – Airplane configured with maximum fuel, two AIM-9M AAMs, and two 2,000-lb bombs Example Mission Profile • Predictions were compared to literature values provided by: Defense Update International (1987) • Predicted Value: 770 naut miles • Published Value: 760 naut miles

9

Predicting Performance • Performance predictions are more difficult to accurately achieve in the absence of actual flight test data • Aerodynamic Efficiency will be a function not only of the Mach number, but of the g-load – As the wing bends and twists at high g-load, its aerodynamic efficiency will degrade – Many empirical sources in the open literature account for fuselage effects, canard effects (if applicable), and even Mach number effects – Relatively little data has been published quantifying g-load effects – One of the few resources that has been published, however is NASA-TP-3414 (shown)

10

Aircraft Performance and Mission Analysis • Aircraft design begins and ends with performance and mission analysis – It is what the customer is paying for and how the airplane will be judged

• Performance and mission analysis both begin with establishing the drag polar • Evaluations of fighter aircraft are today conducted on the basis of broad performance trades – not merely individual design points – Energy Maneuverability Theory changed how fighter airplanes are designed and evaluated beginning in the late 1960s

• For many aircraft and engines flying today, there is a significant amount of published data readily available to the public domain

11

Bibliography Principal Design, Performance and Mission Analysis References Mattingly, Jack D., William H. Heiser, and Daniel H. Daley. Aircraft Engine Design. Washington DC: American Institute of Aeronautics and Astronautics, 1987. Raymer, Daniel P. Aircraft Design: A Conceptual Approach. Washington DC: American Institute of Aeronautics and Astronautics, Inc., 1989. Roskam, Jan. Airplane Design. Part I - VIII. Ottawa KS: Roskam Aviation and Engineering Corporation, 1989.

Other Design References Abbott, Ira H., and Albert E. von Doenhoff. Theory of Wing Sections. New York: Dover Publications Inc., 1949. Asselin, Mario. An Introduction to Aircraft Performance. Reston, VA: American Institute of Aeronautics and Astronautics, Inc., 1997. Goldsmith, E.L. and J. Seddon, ed. Practical Intake Aerodynamic Design. Washington DC: American Institute of Aeronautics and Astronautics, Inc., 1993. Heinemann, Edward H., Rosario Rausa, and K. E. Van Every., Aircraft Design. Baltimore MD: The Nautical and Aviation Publishing Company of America, 1985. Hess, R. W. and H. P. Romanoff. Aircraft Airframe Cost Estimating Relationships: Fighters. N-2283/2AF. Santa Monica CA: Rand Corp.,1987. Stinton, Darrol. The Design of the Airplane. New York: Von Nostrand Reinhold Company, 1983. Roskam, Jan. Airplane Flight Dynamics and Automatic Flight Controls. Part I. Ottawa KS: Roskam Aviation and Engineering Corp., 1979. 12

Bibliography Biographies and Autobiographies Coram, Robert, Boyd: The Fighter Pilot who Changed the Art of War. New York: Little, Brown and Company, 2002. Hampton, Dan. Viper Pilot. New York: HarperCollins, 2012. Heinemann, Edward H. and Rosario Rausa. Ed Heinemann, Combat Aircraft Designer. Annapolis, MD: Naval Institute Press, 1980. Johnson, Robert S. Thunderbolt! Spartanburg SC: The Honoribus Press, 1958.

Other References Brown, Craig. Debrief: A Complete History of U.S. Aerial Engagements 1981 to the Present. Atglen, PA: Schiffer Publishing, 2007. Burton, James. Letting Combat Results Shape the Next Air-to-Air Missile. Washington DC: U.S. Department of Defense, 1986. Cohen, Eliot A., ed. Gulf War Air Power Survey. Volume I - V. Washington DC: U.S. Department of Defense, 1993. Herbst, W. B. “Dynamics of Air Combat,” Journal of Aircraft 20 (July 1983):594-98. Herbst, W. B.“Future Fighter Technologies,” Journal of Aircraft 17 (August 1980): 561-566. Huenecke, Klaus. Modern Combat Aircraft Design. Annapolis, MD: Naval Institute Press, 1987. Jane’s Aero-Engines. Issue 11. Edited by Bill Gunston. Coulsdon, UK: Jane’s Information Group, 2001. Jane’s All the World’s Aircraft. Coulsdon, UK: Jane’s Information Group. (multiple editions) 13

Bibliography Other References (continued) Nguyen, Luat T., M. E. Ogburn, W. P. Gilbert, K. S. Kibler, P. W. Brown, and P. O. Deal. Simulator Study of Stall/Post-Stall Characteristics of a Fighter Airplane with Relaxed Longitudinal Static Stability. NASA TP-1538. Washington DC: National Aeronautics and Space Administration, December 1979. Pavlovic, Predrag, and Nenad Pavlovic. Fighter Performance in Practice: Phantom versus MiG-21. Belgrad, Serbia:Naucna KMD, 2009. Saltzman, Edward J., and John W. Hicks. In-Flight Lift-Drag Characteristics for a Forward-Swept Wing Aircraft. NASA TP-3414. Washington DC: National Aeronautics and Space Administration, December 1994. Shaw, Robert L. Fighter Combat Tactics and Maneuvering. Annapolis MD: Naval Institute Press, 1985. St. Peter, James. The History of Aircraft Turbine Engine Development in the United States. Atlanta GA: American Society of Mechanical Engineers, 1999. Torenbeek, Egbert. Synthesis of Subsonic Airplane Design. Delft, Netherlands: Delft University Press, 1988.

14