Aero Engineering 315

Lesson 2

History of Aeronautical Designand

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 RequirementsOperational 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

DecisionMaking

Test concepts against requirementsModel the systemCollect InformationIdentify problems

Consider AlternativesExplain/JustifyCosts and BenefitsScheduleMay involve politics

Create ideasBrainstormThink of PossibilitiesIntegrate existing & surfacing technology

*Leland M. Nicolai, “Designing a Better Engineer,” Aerospace America, April 1992

PRO

VID

ES A

FR

AM

EWO

RK

TO

SOLV

E IL

L D

EFIN

ED P

RO

BLE

MS

The Design Spiral

Radius of Spiral Suggests Range of Feasible Choices

IncreasingInformation

AnalysisAnalysis SynthesisSynthesis

DecisionsDecisions

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

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

X1

2

3 45

6

7

8

9

10

11

12

13

TOTAL RANGE = 5790 NM

1. TAKEOFF/CLIMB TO BCM/BCA 8. ESCAPE (M 0.85, 500 NM)2. CRUISE CLIMB 9. CLIMB TO BCM/BCA3. REFUEL 10. CRUISE CLIMB4. CRUISE CLIMB 11. DESCENT TO ORBIT5. DESCENT TO 200 FT AGL 12. 30 MIN LOITER6. PENETRATION (M=0.85, 1130 NM) 13. LAND7. WEAPONS DELIVERY (24,000 LBS INTERNAL AND 37,500 LBSEXTERNAL 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

Advanced Tactical Fighter (ATF)1981: USSR introduced MiG-31 (improved MiG-25)1981 (Nov): Air Force developed a requirement for an Advanced Tactical

Fighter1984: USSR introduced MiG-29 (F-16 equivalent)1985 (Sep): Air Force issued formal ATF “request for proposal” to major

defense contractors1986: USSR introduced SU-271986 (31 Oct): Air Force narrows field of ATF competitors to two:

Lockheed and Northrop/McDonnell Douglas1990 (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-222005 (Dec): Expected F-22 Initial Operational Capability (IOC) (current

number of production F-22s is now 339)

Joint Strike Fighter1984: USSR introduced MiG-29 (F-16 equivalent)

1986: USSR introduced SU-27

1993: 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

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 2.1.1 thru 2.2.2 and 2.4 thru 2.6 In Class

Flow properties Perfect gas law Hydrostatic equation Standard atmosphere Altimetry

Air Refueling

Active Ranger

BattleManagement

TILL/BILL

High Energy Laser

IRST

B747-400F

Pressure Bulkhead

IRSTs

Nose-Mounted

Turret

IRST

Airborne Laser (YAL-1A)