Aircraft Design Class 2008 - Virginia Techmason/Mason_f/SD1LSamWilson.pdfsystematic approach to the design of an aircraft. ... Define wing & horizontal stabilizer geometry ... RALS

Aircraft Design ClassAircraft Design Class

Sam B. Wilson III

Chief Visionary Officer

AVID LLC

www.avidaerospace.com

9 September 2008

9 Sept.’08 / pg # 2

OOTTTTTTTactical Technology OfficeTactical Technology Office

9 Sept.’08 / pg # 3

Design MethodsDesign Methods

What Shape?

What Size?

9 Sept.’08 / pg # 4

Design Design ““As DrawnAs Drawn””

Computer evaluation

of Conceptual Designs

“As Drawn” Assumesfixed external mold-lines

Weight as independentvariable - “loopclosure”

JSF X-35BJSF X-35B

9 Sept.’08 / pg # 5

To design a supersonic fighter/attack aircraft thatoffers the operational flexibility of Short Takeoff andVertical Landing (STOVL)

Need to make the same design compromises as aconventional fighter, plus one: use the availablethrust in a manner that allows a controlled verticallanding

This single added constraint requires a moresystematic approach to the design of an aircraft.

Integration Challenge:Integration Challenge:

9 Sept.’08 / pg # 6 Ref NASA CR-177437

Define wing & horizontal stabilizer geometry

Located engine “vertical thrust” center with

respect to aerodynamic center

V/STOL Aircraft Design ProcessV/STOL Aircraft Design ProcessStep 1Step 1

9 Sept.’08 / pg # 7

Add minimum length inlet/diffuser

Add cockpit and forebody

Ref NASA CR-177437


9 Sept.’08 / pg # 8

Add vertical tails

Assign location dependent masses

landing gearlanding gear

flight controlsflight controls

radarradar

Ref NASA CR-177437


9 Sept.’08 / pg # 9

Add Payload bays / weapon hardpoints

Add fuel tanks

Assign location independent masses

Service centersService centers

AAvionicsvionics

APUAPU

Ref NASA CR-177437


9 Sept.’08 / pg # 10

Add lead weight ballast!

CG too far forwardCG too far forward

Vertical thrust center too far aft Vertical thrust center too far aft


9 Sept.’08 / pg # 11

Overview of StudyOverview of Study

Description of four candidate propulsionsystems which can be based on a single gasgeneratorFirst order effects of the four propulsionsystems on the sizing of a STOVL fighter

9 Sept.’08 / pg # 12

Design MissionDesign Mission

9 Sept.’08 / pg # 13

STOVL Lift Systems StudySTOVL Lift Systems Study

RALS RULS MFVT L+L/C0

1000

2000

3000

4000

5000

gas generatorAugmentorrear/ventralC & Aductsfront nozzle

Unscaled Propulsion System WeightsW

eig

ht

(lb

)

9 Sept.’08 / pg # 14

Thrust to Weight DefinitionsThrust to Weight Definitions

(review)(review)

Engine T/W = Uninstalled Max A/B ThrustCTOL Engine Weight

System T/W = Installed Max A/B Thrust Total Propulsion System Weight

Lift System T/W = Balanced Vertical ThrustTotal Propulsion System Weight

9 Sept.’08 / pg # 15

STOVL Lift System PerformanceSTOVL Lift System Performance

R A L S R U L S MFVT L+L/C

0

2

4

6

8

10

Vertical ThrustMax. Aug Thrust

System Thrust to WeightT

hru

st

/ W

eig

ht

9 Sept.’08 / pg # 16

STOVL Lift System BreakoutSTOVL Lift System Breakout


0

5000

10000

15000

20000

25000

30000

35000

AirframePropulsionFixed Equip.

PayloadFuel

Group Weights

Wei

gh

t (l

b)

9 Sept.’08 / pg # 17

STOVL Gross Weight SensitivitySTOVL Gross Weight Sensitivity


0

1

2

3

4

5

Design Point SensitivityP

erce

nt C

hang

e

10% change in manuver performance

9 Sept.’08 / pg # 18

Cruise Engine Thrust for L+L/CCruise Engine Thrust for L+L/C

1.00.90.80.70.60.5

0

5,000

10,000

15,000

20,000

25,000

30,000

L/C eng Vert. Thrust

Lift engine Thrust

Thrust Distribution

Aft Nozzle Location

Th

rust

(lb

)

Lift engine at .42 LC.G. at .58 L

9 Sept.’08 / pg # 19

Hover BalanceHover Balance

Thrust Required for Vertical Landing

-

5,000

10,000

15,000

20,000

25,000

30,000

35,000

40,000

45,000

0.42 0.46 0.50 0.54 0.58 0.62 0.66 0.70 0.74

Station Location

9 Sept.’08 / pg # 20

Off Design PerformanceOff Design Performance

Fallout Performance

RALS RULS MFVT L+L/C

Ps @ M=1.50, 30k'

Nz @ M=1.20, 40k'

Nz @ M=0.60, 20k'

410

4.05

3.14

1123

4.04

3.77

861

4.03

3.59

583

4.05

3.34

9 Sept.’08 / pg # 21

Conclusion for Lift EnginesConclusion for Lift Engines

If high maneuver performance and/or dry super-cruise is required, lift engines have limitedvalue (mission dependent)

Lift System thrust to weight is not a strongfunction of engine T/W for many engineconfigurations

Factors other than mission performance will benecessary to choose a propulsion system

9 Sept.’08 / pg # 22

9 Sept.’08 / pg # 23

CNA Air Panel StudyCNA Air Panel Study

-- Tactical Air Assets for Carrier Task Force

Fighter & Attack Aircraft vs. Multi-Mission Aircraft

STOVL vs. Conventional Carrier Based Aircraft

No Utility Aircraft Assessments

- Used STOVL Strike Fighter TOR Missions

Latest Statement of Future Naval Mission Requirement

Multi-Mission (F/A & SSF) Do All Missions

Subsonic Attack Aircraft Point Designed for Air to Ground

"Blue Water" Fighter Optimized for Fleed Air Defense

- Emphasis on Time Based Technology Trends

Baseline was US/UK ASTOVL "1995 TAD" Assumptions

“1990 TAD” Timeframe Allows for "What is Available"

NASA-Ames Study PlanNASA-Ames Study Plan

9 Sept.’08 / pg # 24

Technology Availability DateTechnology Availability Date

Common: Engine Cycle, Weapons, Avionics, etc.

1990-TAD 1995-TAD

Radar Absorbing Material + 0% + 5%

Internal Weapons Carriage No Yes

1.5M Supersonic Cruise A/B “Dry”

Design Load Factor 7.5 9.0

Technology Factor 90% 85%

Propulsion System T/W ~12 ~15

9 Sept.’08 / pg # 25

DifferentiatorsDifferentiators””1990 TAD1990 TAD”” Aircraft Class Aircraft Class

Fighter Multi-Mission Attack

Structural Tech. Factor -10% -10 % -10%

Design Load Factor 6.5 g 7.5 g 6.5 g

Survivability Impacts No No No

Dry Super-cruise No No No

Plan form Variable Standard Standard

Wing Pivot +30% 0 0

Tail Surfaces Standard Standard Standard

9 Sept.’08 / pg # 26

DifferentiatorsDifferentiators"1995 TAD" Aircraft Class"1995 TAD" Aircraft Class

Fighter Multi-Mission Attack

Structural Factor -15% -15 % -15%

Design Load Factor 9.0 g 9.0 g 6.5 g

Survivability Impacts No Yes Yes

Dry Supercruis Yes Yes No

Planform Variable Diamond Flying Wing

Wing Pivot +30% 0 0

Tail Surfaces Conventional Conventional None

9 Sept.’08 / pg # 27

Ames CNA Study DescriptionAmes CNA Study Description

Three Aircraft Classes

Direct-Lift STOVL

Sea-Based (“Cat / Trap”)

Land-Based

Two Technology Timeframes

1990-TAD

1995-TAD

Philosophy

ACSYNT - Design Synthesis Code

9 Sept.’08 / pg # 28

Baseline Design MissionBaseline Design Mission

250 nmi cruise0.85M at Sea Level

400 nmi cruiseBest Altitude and Mach

150 nmi dash1.5M at 50000 ft

60 minutes loiterBest Mach at 35000 ft

2 min combat1.5M at 50000 ft

Loiter0.3M at Sea Level

High Value Stores Retained for Landing2 Long-Range, Air-to-Air Missiles2 Short-Range, Air-to-Air MissilesGun and Ammo

9 Sept.’08 / pg # 29

Aircraft Class DetailsAircraft Class Details

STOVL Sea-Based Land-Based

Fuselage Structure 0 + 30 % 0

Landing Gear Structure 0 + 30 % 0

Carrier Approach No Yes No

Propulsion Weight + 47% 0 0

Landing Hover T/W 1.16 N/A N/A

Reaction Control System Yes No No

Duct Volume Penalty ~10% 0 0

Loiter in Pattern 10 min 20 min 20 min

9 Sept.’08 / pg # 30

Propulsion SystemsPropulsion Systems

Conventional

Direct-Lift STOVL

9 Sept.’08 / pg # 31

Aircraft EvolutionAircraft Evolution

1990-TAD

1995-TAD

9 Sept.’08 / pg # 32

Baseline AircraftBaseline Aircraft

0

20000

40000

60000

80000

100000

Take

off

Wei

ght

(lb)

Sea

-Bas

ed

Lan

d-B

ased

STO

VL

Sea

-Bas

ed

Lan

d-B

ased

STO

VL

1990-TAD 1995-TAD

9 Sept.’08 / pg # 33

Augmentation in HoverAugmentation in Hover

0

20,000

40,000

60,000

80,000

100,000

Tak

eoff

Wei

gh

t (l

b)

Sea-Based Land-Based STOVL

Baseline

Derivative

1990-TAD STOVL1990-TAD STOVL

9 Sept.’08 / pg # 34

Dry Super-cruise RequiredDry Super-cruise Required

0

20,000

40,000

60,000

80,000

100,000

Tak

eoff

Gro

ss W

eig

ht

(lb

)

Sea-Based Land-Based STOVL

Derivative

Baseline

1990-TAD Conventional1990-TAD Conventional

9 Sept.’08 / pg # 35

1990-TAD Growth Factor1990-TAD Growth Factor

0

5

10

15

20

25

Gro

wth

Fac

tor

0 100 200 300 400 500 600 700

Mission Radius (nm)

DesignMissionRadius

Sea-Based

STOVL

9 Sept.’08 / pg # 36

1995-TAD Growth Factor1995-TAD Growth Factor

0

5

10

15

20

25

Gro

wth

Fac

tor

0 100 200 300 400 500 600 700

Mission Radius (nm)

Sea-Based

STOVL DesignMissionRadius

9 Sept.’08 / pg # 37

Required Hover Thrust MarginRequired Hover Thrust Margin1995-TAD STOVL1995-TAD STOVL

0

20000

40000

60000

80000

100000

1.15 1.2

Take

off

Gro

ss W

eigh

t (lb

)

1.25 1.3 1.35

1.16 T/W requirement

Land-Based

Baseline STOVL

T/Whover

Sea-Based

9 Sept.’08 / pg # 389 Sepppt.’08 / pg # 38

9 Sept.’08 / pg # 39

9 Sept.’08 / pg # 40

9 Sept.’08 / pg # 41

9 Sept.’08 / pg # 42

9 Sept.’08 / pg # 43

STOVL Baseline Aircraft

Direct Lift Remote Fan L+L/C

T.O. Gross Weight (LB) 36,331 36,866 39,679

Length (ft) 48. 54. 54.

Wing Area (ft2) 345. 400. 440.

Span (ft) 29.6 32.8 35.1

Thrust (Vertical landing) 29,289 42,142 47,102

Thrust (SLS Dry) 29,289 26,021 27,595

Propulsion Weight (LB) 8,381 8,419 10,014

Engine Weight (LB) 7,532 6,723 7,097

Fuel Weight (LB) 11,387 10,698 11,207

9 Sept.’08 / pg # 44

STOVL Aircraft (Ratios)

Direct Lift Remote Fan L+L/C

Growth Factor 3.20 2.37 3.52

Aspect Ratio 2.5 2.6 2.8

Wing Loading (LB/ft2) 105.3 92.2 90.2

Vertical Thrust/WPS 3.49 5.01 4.70

Dry Thrust/TOGW 0.81 0.71 0.70

Max Thrust/TOGW 1.30 1.14 1.12

ESF 1.21 1.08 1.14

Prop. Sys. Fraction 23.1% 22.8% 25.2%

Fuel Fraction 31% 29% 28%

9 Sept.’08 / pg # 45

0

2

4

6

8

10

12

14

16

18

N.

M./100#

Subsonic M=1.4

Cruise Efficency

DL

LPLC

RFSF

Subsonic 1.4 Mach Number

18

16

14

12

10

8

6

4

2

0

N.m./100#

Cruise Efficiency

9 Sept.’08 / pg # 46

0

5,000

10,000

15,000

20,000

25,000

30,000

35,000

40,000

Weight

D.L. L+L/C A.L.

Type of A/C

Weight Breakdown

Fuel

Aux. Lift

Engine

Airframe

Payload

9 Sept.’08 / pg # 47

ConclusionsConclusionsImproved enginetechnology allowsthe elimination oflanding thrust-to-weight as the mainSTOVL designconstraint.

The STOVLpropulsion systemdecision drives theaerodynamic shape.

9 Sept.’08 / pg # 48

Engine Weight Engine Weight vsvs. Empty Weight. Empty Weight

9 Sept.’08 / pg # 49

Engine Weight Engine Weight vsvs. Empty Weight. Empty Weight

0.00

0.10

0.20

0.30

0.40

0.50

0.60

0.70

0.80

WEng/OWE

OWE/WG

9 Sept.’08 / pg # 50

Distributed PropulsionDistributed Propulsion

DARPA PM: Dr. Thomas Beutner (TTO)

Advanced ESTOL transport configuration development incorporating

distributed propulsion technology and airframe / propulsion integration.

Tools UsedAVID RAPT

AVID HighLift

AVID ACS

FUN3D

CFL3D

USM3D

Powered high-lift systems

• Upper surface blowing

• Augmenter wing

• Blown tails

278-ft field length

15,000 lb -- 25,000 lb payload

Demonstrated distributed propulsion performance

Identified new benefits for Distributed Propulsion

9 Sept.’08 / pg # 51

Span Blowing versus Total LiftSpan Blowing versus Total Lift

Spanloadings for increasing blown span.

CT=1.67, 18 deg USB flaps

0

20

40

60

80

100

120

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0

y/(b/2)

Cl

x c 38% span blowing

55% span blowing

72% span blowing

Drag Polars for increasing blown span.

CT =1.67, 18 deg USB flaps

0.0

1.0

2.0

3.0

4.0

5.0

6.0

7.0

0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8

CD

CL

38% span blowing

55% span blowing

72% span blowing

9 Sept.’08 / pg # 52

Canard over door

Small Engines“blowing” ControlSurfaces duringSTOL operationsto reduce size

Small Engines“blowing” FlapsDuring STOLoperations

Variable # of engines used in cruise

(designed to cruise at best SFC)

Notional DemonstratorNotional Demonstrator

9 Sept.’08 / pg # 53

AVID-ACS Type OutputAVID-ACS Type Output

Engine is sized by maneuver or VL (1.2*GW)

Fuel is generated by Fuel burn:

Thrust required = weight/ (L/D)

Fuel = Thrust * SFC

Airframe weight is structure to hold everything:

Fuel tanks = Fuel weight * 3%

Landing Gear = TOGW * 6%

Tails = Control power sizing

Wing = f (AR, Sweep, Area, Taper, T/C)

9 Sept.’08 / pg # 54

ACSYNT Institute: Aircraft Design ToolsACSYNT Institute: Aircraft Design Tools

Parametric design tool

for aircraft synthesis...

Concept

Development

Preliminary

Design

Detailed

Design

•Lots of Designs

•Tradeoff Studies

•“Requirements

Optimization”

•In-depth analysis

•Narrowed to few designs

•Detailed optimization

•Detailed analysis

•Subsystem design &

optimization

ACSYNT

DDDDDDDDDDDDeeeeeettttttaaaaaaiiiiiilllllleeeeeedddddd

9 Sept.’08 / pg # 55

ACSYNT

Drawbacks

• Practical – Human designer notinformed as to why final design waschosen

•Technical – Can’t handle step changes(i.e. number of engines, type of controlsurface). Must use continuousfunctions in coding.

???

9 Sept.’08 / pg # 56

Artificial IntelligenceArtificial Intelligence

for Aircraft Designfor Aircraft Design

PROS

• Hailed as “Future of AircraftDesign”

•Capture the thoughts of the“great designers” and apply tocomputer aided designprograms

CONS

• Designers are constantlyevolving, requiresevolving code

• Conflicting inputs fromconflicting designers

•Impossible torecreatespontaneousthoughts ofhumans

9 Sept.’08 / pg # 57

Goals of Computer Aided Aircraft DesignGoals of Computer Aided Aircraft Design

Optimization ProgramsOptimization Programs

• Reduce dependence on wind tunnel testing

• Computer code offers “Real Time Design”

• Much smoother transition from paper toprototype

• Reduces common “headaches” associatedwith current aircraft design

• No more “Point Design”

9 Sept.’08 / pg # 58

http://aero.stanford.edu

/reports/nonplanarwings/CWingOpt.html

9 Sept.’08 / pg # 59

Vehicle data ex cept MAV from NASAGSFC / Wallops UAV Databasehttp://uav .w ff.nasa.gov /db/uav _index .html

Unmanned Air VehiclesUnmanned Air Vehicles

0.01

0.1

1

10

100

1000

10000

100000

0.1 1 10 100Wing Span, m

Tot

al W

eigh

t, kg

Gasoline

Electric

Turbine

DARPA MAV

Tr uck

Ter n

Spectr e II

SkyeyeShadow 600

Shadow 200

STM 5B

RaptorPr owler

Pr edator

Por terPioneer

Per seus B

Pathfinder

Outr ider

Model 410

Model 350, M1

Model 324, M1

Javelin

Hunter

Huntair

Hawk-i 7B

Gnat 750

Global Hawk

Fr eewing

Fir ebee

Exdr one Eagle Eye

Dar kstar

Chir on

Aer osonde

Pointer

Gasoline

Electric

Turbine

Theseus

LADF 9” 3.8#

Black Widow

9 Sept.’08 / pg # 60

Caltech

AeroVironment

Microbat

Lutronix

Kolibri

Lockheed Sanders

Stanford Research Institute

100 g.

5 km range, 30 min.

Autonomous Nav.

Video imagery

Mentor

320 g.

30 min.

Hover/translate

GPS

Autopilot

10 g.

3 min.

Acoustic sensors

MEMS wings

50 g.

electrostrictive

polymer

artificial

muscle

Flapping flight

50 g.

1 km range

Teleoperated

Video imagery

Micro Air VehiclesMicro Air Vehicles

MicroSTAR

Black Widow

9 Sept.’08 / pg # 61

Kolibri Micro Air VehicleKolibri Micro Air Vehicle

%

%

0

25

50

75

100

125

150

175

0 10 20 30 40

Use

ful

Lo

ad,

Wp

l (g

mf)

LuMAV-3A Endurance, E (min)

%

% 175

150

125

100

75

50

25

0

0 5 10 15

Use

ful

Fue

l L

oad

, W

f (g

mf)

LuMAV-3A Range, R (nmi)

fuel

payload

UTRONIX corporation

Flight Speeds Max. demonstrated flight speed in hover mode: 22 kts

Max. predicted flight speed transitioned flight mode: 88 kts

Min. turn radius (for maneuvering): 0 ft

Max. rate of climb demonstrated at 0 kts forward speed: 4800 fpm

Max. controllable rate of descent demonstrated: 1700 fpm

Endurance Max. predicted endurance with no payload: 34 minutes

Demonstrated endurance with mission package: 16 minutes

Range Max. hover-mode range predicted: 15 nmi (ferry range)

Max. transitioned range predicted: 50 nmi (ferry range)

9 Sept.’08 / pg # 629 Septt.’008 / pg # 662

OAVs on the BattlefieldOAVs on the Battlefield

National and Theater

Intelligence,

Surveillance

and Reconnaissance

Systems

Highly SurvivableUpper Tier – Target Acquisition, Cueing

And Prosecution

Organic Air VehiclesAct As the Lower Tier

- Local RSTA

Called by IUGS for

Cross reference prior

to waken Human

Pathfinder for

Ground Vehicles

Final ID before

Authorization to Fire

Answer Human

request of

Information!

Perimeter

Surveillance - IR

against Infantry

9 Sept.’08 / pg # 63

Ducted Fan UAV Inboard ProfilesDucted Fan UAV Inboard Profiles

Batteries

Payloads

Fuel Tanks

Video CPU

GPS CPU

Antenna

Servos

Flight Computer

Memory

Collision

Avoidance

GPS Antenna

IR Camera

Avionics and

Electronics

Top

Payload

Electrical

Subsystems

Duct

Fuel

Tank Fixed

Stators

4 Quadrant VanesLanding Ring

Lower Payload Bay

Engine

Fan

9 Sept.’08 / pg # 64

MEDIUM SMALL

MICROScalable Solution = family of vehiclesScalable Solution = family of vehicles

67” Fan Diameter

Hover and low speed flight

testing completed

25” Fan Diameter

Fully autonomous flight

Full flight speed regime

31” OAV FCS Vehicle

• Low cost manufacturing

• Common components

• Full autonomy

11.5” Fan Diameter

Fully autonomous flight over

full flight speed regime, field

tested by Military in Hawaii

Flight Proven

Autonomous

25

Fu

Fu

LARGE

7” Fan Diameter

Successful hover, low speed

& high speed transition

FCS Vehiclele

ost manuufacturing

mon compponents

utonomy

er

d

9 Sept.’08 / pg # 65

Class IClass I

ARMY FCS• AVID Supports Honeywell in

Contributing Aircraft Design

and Analysis and Propeller

Design and Analysis

• AVID is part of a larger team

for Honeywell including AAI,

Locust, Techsburg

AVID Tools and Expertise• AVID lead for aerodynamic design

through PDR

• AVID designing fan for

performance and acoustics

• Configuration CFD using TetRUSS

and FUN3D

• Performance in AVID OAV

Status• Concept design is underway

• Wind tunnel testing to happen in first

months of 2008

• First flight in 2009

Documents

Aircraft Design Class 2008 - Virginia Techmason/Mason_f/SD1LSamWilson.pdfsystematic approach to the design of an aircraft. ... Define wing & horizontal stabilizer geometry ... RALS