Aero Engineering 315 Lesson 2 History of Aeronautical Design and Introduction to Aircraft Design

First a little more admin…  Seating chart  Pick up any missing materials at the back

 Identify major figures in the development of aeronautics and their contributions  State the reasons for designing a new aircraft  State the steps of the design process Overview/Outcomes

Aviation History Montgolfier brothers Cayley * Lilienthal * ChanuteLangley *Wright Brothers *

Why Design?  Q: Why design a brand new airplane?  A: To satisfy a need Threat, shortcoming, cheaper, change in doctrine, vulnerability  Q: Who identifies the need?  A: The user (or the manufacturer) Via Mission Need Statement (MNS)

Mission Requirements Operational Requirements Document (ORD)  Defined by the user (ACC, AMC, etc.)  Quantify desired aircraft capabilities  What are the measures of merit aircraft is judged on?  Requirements often conflict - must compromise  Critical requirement may drive design (speed, range, etc.) (stealth, affordability, performance, logistics, supercruise, maneuverability, lethality, survivability…) (A-10 gun)

Design Process  Analogous to the scientific method  Six steps: Define the problem (purpose, performance parameters, MOMs) Collect data (available tech, existing designs, analysis methods) Create/synthesize one or more design concepts Select types of analysis to evaluate design(s) Perform analyses Make decisions  If necessary, return to step 1 or 2 and repeat process

Design Cycle Analysis Synthesis Decision Making Test concepts against requirements Model the system Collect Information Identify problems Consider Alternatives Explain/Justify Costs and Benefits Schedule May involve politics Create ideas Brainstorm Think of Possibilities Integrate existing & surfacing technology *Leland M. Nicolai, “Designing a Better Engineer,” Aerospace America, April 1992 PROVIDES A FRAMEWORK TO SOLVE ILL DEFINED PROBLEMS

The Design Spiral Radius of Spiral Suggests Range of Feasible Choices Increasing Information Analysis Synthesis Decisions

Design Phases  Conceptual Design - “ideas”, multiple designs  Preliminary Design - “models”, wind tunnel testing, computer optimization  Detailed Design - “prototype”, flight testing, fly-offs, manufacturing processes defined DESIGN PROCESS MODEL IS USED ITERATIVELY DURING EACH PHASE

Design Cycle  Iterative process  Occurs within each phase of design  Ideally converges to an optimum solution  May result in multiple solutions

Multiple Solutions Same Mission Same Payload Different Design Decisions Wing Shape Engine number and location Same Performance Differences Durability Maintenance

Sample Mission: B-1  What was the need?  What are the requirements?  What are the major design features?  How do they help the design meet the requirements?

B-1 Design Mission 1. TAKEOFF/CLIMB TO BCM/BCA8. ESCAPE (M 0.85, 500 NM) 2. CRUISE CLIMB9. CLIMB TO BCM/BCA 3. REFUEL10. CRUISE CLIMB 4. CRUISE CLIMB11. DESCENT TO ORBIT 5. DESCENT TO 200 FT AGL MIN LOITER 6. PENETRATION (M=0.85, 1130 NM)13. LAND 7. WEAPONS DELIVERY (24,000 LBS INTERNAL AND 37,500 LBS EXTERNAL ORDNANCE INCLUDING 8 SRAM, 12 ALCM, AND 8 B-61)

B-2 Redesign Analysis: Not enough Lateral/Directional control Lt Col Lewelen “Doc” Dougherty suggested sawtooth design

Satisfy a need for stealth!  Flight Control Issues No vertical surfaces Static instability Ride quality  No air data probes

Advanced Tactical Fighter (ATF) 1981:USSR introduced MiG-31 (improved MiG-25) 1981 (Nov):Air Force developed a requirement for an Advanced Tactical Fighter 1984:USSR introduced MiG-29 (F-16 equivalent) 1985 (Sep): Air Force issued formal ATF “request for proposal” to major defense contractors 1986:USSR introduced SU (31 Oct): Air Force narrows field of ATF competitors to two: Lockheed and Northrop/McDonnell Douglas 1990 (27 Aug): First flight of Northrop/MD YF-23 (test pilot Paul Metz) 1990 (29 Sep): First flight of Lockheed YF-22 (test pilot Dave Ferguson) 1991 (23 Apr): Air Force selected Lockheed YF-22 design as winner of ATF competition (originally 750 production F-22s expected but later reduced to 648) 1994 (10 Feb): Air Force reduced number of production F-22s from 648 to 422 as a result of military downsizing 1996 (2 Apr):Russia (former USSR) introduced SU-37 (improved SU-27) 1997 (7 Sep): First flight of F-22A (test pilot Paul Metz) 1999 (12 Jan): Russia unveiled the Multi-Functional Fighter (known as “Project 1.42” in the West) and claimed it can outperform the F (Dec):Expected F-22 Initial Operational Capability (IOC) (current number of production F-22s is now 339)

Joint Strike Fighter 1984:USSR introduced MiG-29 (F-16 equivalent) 1986:USSR introduced SU :DoD initiated Joint Advanced Strike Technology (JAST) program to address long term attack aircraft force structure requirements for different branches of U.S. Mil 1995: Air Force/Navy/Marines/UK Navy/UK Air Force developed initial requirements document for Joint Strike Fighter 1996 (Apr):Russia (former USSR) introduced SU-37 (improved SU-27) 1996 (Nov):Lockheed Martin and Boeing awarded contracts to develop concept demonstration aircraft 2000 (Sep): First flight of Boeing X-32 (test pilot Fred Knox) 2000 (Oct): First flight of Lockheed X-35 (test pilot Tom Morgenfeld) 2001 (Oct): Air Force selected Lockheed X-35 design as winner of JSF competition, largest military aviation contract ever at over $200 billion 2006:Projected beginning of JSF (F-35) production 2010:Projected JSF (USMC version) Initial Operational Capability (IOC) (current number of production aircraft is 3002: 1763 USAF, 480 USN, 609 USMC, 60 UK Navy, 90 UK AF) 2011:Projected JSF (USAF version) IOC 2012:Projected JSF (USN and UK versions) IOC

USSR (~late 40’s) Need for a superior air-to-air fighter German Me-163B rocket fighter (1944) Rolls-Royce Nene Turojet Engine Soviet I-270 rocketplane (1947) MIG - 15 Espionage and design are definitely related…

Points to Remember  We design to meet a need  Must satisfy certain requirements Many conflict - must compromise A critical requirement may drive the design  3 phases of design: conceptual, prelim, detail  Design process: 3-step design cycle: synthesis, analysis, decision making Is iterative and cyclical Involves many disciplines Compromise is essential Requires creative and analytical thinking May provide multiple solutions (F-22 vs F-23) Final judge is the user

Next Lesson (T3)…  Prior to Class Read thru and 2.4 thru 2.6  In Class Flow properties Perfect gas law Hydrostatic equation Standard atmosphere Altimetry

Air Refueling Active Ranger Battle Management TILL/ BILL High Energy Laser IRST B F Pressure Bulkhead IRSTs Nose- Mounted Turret IRST Airborne Laser (YAL-1A)