Polaris – DLR

 

 

Polaris

Future Aircraft Design Concept

Team
Tobias Dietl
Jonas Karger
Katrin Kaupe
Andreas Pfemeter
Philipp Weber
Alexander Zakrzewski

Academic Support and Advisors
Institute of Aircraft Design, University of Stuttgart
Prof. Dr. Andreas Strohmayer
Ingmar Geiß

Contact: polarisaircraftdesign@gmail.com

Submitted on July 1st 2018

Abstract

Looking at aviation in 2045 a competitive operation of aircraft will not only be dependent on highly efficient
aircraft, but also on passenger comfort, manufacturing effort and an excellent life cycle.

The present report provides a breakdown of an aircraft design study with consideration of future aviation

goals and proposals that might further improve the design with regard to pollutant and noise emissions.

An adjusted design process is used to find the synergies of all components and to combine their advantages
instead of evaluating each component itself. Correlating with the design process, the final aircraft design is
discussed with its results, options and challenges. To validate the quality of the results, the reference aircraft
CSR-01 (A320) is emulated in relation to energy consumption, mass estimation and aerodynamics with a devi-
ation of less than 1 %.

With special remark to the used key technologies the report provides information about current technical
states, future improvements and an estimation of their qualitative efficiency in 2045. Except for high tem-
perature superconducting (HTS) material all other used technologies are at least tested on a demonstrator or
available for series production by now. HTS materials currently attain technology readiness level 4 and therefore
illustrate that the used key technologies of this aircraft design are about to be available before 2025.

Finally, the improvements of this design are based on the synergistic integration of each component, resulting
in a single-aisle transport aircraft that reduces the energy consumption for an equal mission by 61.39 % in ref-
erence to an A320 in 2005. A multi-functional fuselage concept combined with a calculated liquid hydrogen fuel
system and a turboelectric power transmission complete the aircraft design reducing the energy consumption,
manufacturing effort and increasing the reliability and passenger safety.

I

Contents

Nomenclature

List of Figures

List of Tables

1 Introduction

2 Design Decisions

3 Key Technologies

2.1 Design Considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

3.1 Propulsion Chain . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3.2 Multi-functional fuselage concept . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3.3 Aerodynamics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

4 Design Overview

11
4.1 Fuselage and Wing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
4.2 Gear . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
4.3 Empennage and Propulsion System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
4.4 Fuel System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
4.5 Mass Estimation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
4.6 Technology Readiness Levels

5 Aircraft Performance

18
5.1 Compared key data of Polaris and CSR-01 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

6 Impact on Operation

22
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
6.1 Pollutant Emissions
6.2 Alternative Missions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
6.3 Flight related aspects
6.4 Airport Modifications
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
6.5 Groundhandling and Turnaround . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24

7 Summary

Bibliography

A Gondola fuselage concept

III

V

V

1

2
2

4
4
6
8

25

26

I

Contents

II

Nomenclature

Nomenclature

Abbreviations

MAAMF

Mylar-aluminum/aluminum-Mylar foil

AC

BSCCO

CeRAS

CFD

CFRP

CG

CROR

DC

FAR

GD

HPC

HTP

HTS

IATA

ICAC

IRA

ISA

MAC

MTOM

MME

MZFM

OPR

OME

REVAP

SLI

SR

TET

TLAR

TSFC

TOFL

UHB

ULD

VARI

VeSCo

VTP

YBCO

Alternating current

bismuth strontium calcium copper oxide

Central Reference Aircraft data System

Computational Fluid Dynamics

carbon fibre reinforced plastics

Center of Gravity

Contra-rotating open rotor

Direct current

Federal Aviation Regulations

High- temperature superconductor

high pressure compressor

horizontal tail plane

High – Temperature superconductor

International Air Transport Association

Initial Cruise Altitude Capability

Intercooled Recuperated Aero engine

International Standard Atmosphere

Mean aerodynamic chord

Maximum Take-Off Mass

Manufacturers Mass Empty

Maximum Zero Fuel Mass

overall pressure ratio

Operating Empty Mass

Revolutionäre Arbeitsprozesse

single-line injection

Short Range

Turbine Entry Temperature

Top Level Aircraft Requirements

thrust specific fuel consumption

Take-Off Field Length

ultra-high bypass

Unit Load Device

Vacuum Assisted Resin Injection

Ventilated Shear Core

vertical tail plane

yttrium barium copper oxide

III

Symbols

Latin

Symbol

L/D

cD

cLmax

cLmax
˙m

v1

vs,T O

vs,LDG

cL−Empennage

cLmax,LDG

VV T P,M T OW

VV T P,OEW

Greek

Symbol

α

αempennage

γapproach

ηth

ηth,baseline

Nomenclature

Description

glide ratio

drag coefficient

maximum lift coefficient

lift coefficient, empennage

maximum lift coefficient

decision speed

mass flow

stall speed, take-off configuration

stall speed, landing configuration

maximum lift coefficient, landing configuration

Volume coefficient for the vertical tail in MTOW configuration

Volume coefficient for the vertical tail in OEW configuration

Description

angle of attack

angle of attack, empennage

approach angle

thermal efficiency

thermal efficiency baseline

Unit

–

–

–

–

–

–

–

–

kg/s
m/s
kts

kts

Unit

rad

rad

deg

–

–

IV

List of Figures

List of Figures

1
1.1 Operation evaluation of the A320 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2
2.1 Polaris . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2.2 Design Process
3
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2.3 Different Hybrid Systems
4
2.4 Different Hybrid Systems
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4
3.1 Turboelectric propulsion chain of the Polaris concept . . . . . . . . . . . . . . . . . . . . . . . . .
5
3.2 Core efficiency of different engine concepts [11]
. . . . . . . . . . . . . . . . . . . . . . . . . . . .
6
3.3 Power densities of superconducting and conventional electric machines [17] . . . . . . . . . . . . .
7
3.4 VeSCo Concept [24]
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
7
3.5 Gondola Concept . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
8
3.6 L/D Polars of Polaris and the reference aircraft CeRAS . . . . . . . . . . . . . . . . . . . . . . .
8
cL − cD polars of Polaris and the reference aircraft CeRAS . . . . . . . . . . . . . . . . . . . . .
3.7
8
3.8
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Influence of wing on the empennage
3.9 Function of Coanda-Flap System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
9
3.10 Transition Surface of the morphing Wing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
3.11 Static margin diagram of Polaris
4.1 Three side and isometric view . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
4.2
Integration of fuel system, cargo and propulsion unit . . . . . . . . . . . . . . . . . . . . . . . . . 12
4.3 Fuselage Section and Cabin Layout . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
4.4 Burstcone CROR . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
4.5 Assembly of empennage, propulsion system and fuselage . . . . . . . . . . . . . . . . . . . . . . . 13
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
4.6
. . . . . . . . . . . . . . . . . . . . . . . 15
4.7 Flammability compared between LH2 and kerosene [44]
4.8 Calibration method of component weights based on [48]
. . . . . . . . . . . . . . . . . . . . . . . 15
4.9 Cross section of fuel delivery lines based on [43] . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
5.1
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
5.2 Payload-range-diagram of the short-range and the long-range version of Polaris . . . . . . . . . . 20
6.1 Comparison of greenhouse effects depending on flight altitude [60].
. . . . . . . . . . . . . . . . . 22
6.2 Example on how to optimize the flight path for a smaller greenhouse effect [61]. . . . . . . . . . . 23
6.3 Ramp Layout of Polaris . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24

1500 NM design mission profile of Polaris

Insulation layers tanks [46]

List of Tables

1
1.1 Top Level Aircraft Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
8
3.1 Non-lift-dependent component drag . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3.2
resulting α . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
4.1 Mass Breakdown of Polaris and CeRAS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
4.2 Tank component weights . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
4.3 Technology readiness level . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
5.1 Mission calculation data for the 1500 NM design mission of the Polaris concept
. . . . . . . . . . 19
5.2 Comparison between CeRAS and Polaris for two different mission ranges and the resulting energy

saving taking the two different fuel types into account

. . . . . . . . . . . . . . . . . . . . . . . . 20
5.3 Calculated take-off and landing data for Polaris at MTOM . . . . . . . . . . . . . . . . . . . . . 21
5.4 Compared key data of Polaris and CeRAS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
6.1 Calculated data of alternative missions. Note that the fuel consumption at M a = 0.75 exceeds
the fuel capacity of the short-range version, so the long-range has to be used in this case.

. . . . 23

V

1 Introduction

1 Introduction

A look back at the last years shows that the number of flight movements rose each year to approximately 42
million in 2017 [1]. This number will rise further due to lower fares and increasing flight routes for the foreseeable
future. As a matter of fact, it is necessary to consider new aircraft configurations and propulsion systems as
well as the synergistic integration in the complete aircraft to reduce the energy consumption of transport air-
crafts drastically. Beyond that innovative operating concepts and air operations need to be considered as well [2].

This report focuses on the design of a new single-aisle transport aircraft, using an A320 as reference. The
Best-in-Class version of the A320 from the year 2005 is specified with a design range of 2750 NM at a design pay-
load of 13 608 kg. An own investigation of the A320s’ actual flight range shows that the largest number of flights
is below 1500 NM [3]. In the future new flight routes might be necessary to match customer expectations, but
it is a matter of fact that a mission sector of 1500 NM covers nearly all destinations in Europe, Asia and North
America. The investigation therefore considers 1100 flights on 19 airports in these continents, as these flights
will still be part of future aviation. Figure 1.1 shows the number of flights for its flight distance and the per-
centage of flights in total. A range of 1500 NM covers 85 % of the investigated flight and as there are only a few
flights above 2200 NM, the chosen design point of the present concept is set to 1500 NM at a payload of 13 608 kg.

For the validation of the present design concept,
the A320 is emulated for this design mission. The
RWTH Aachen provides a Central Reference Air-
craft data System (CeRAS) [4], in this the CSR-01,
a modeled A320, is used.
It fulfills the require-
ments of the task and provides all necessary data
from a single source. The advantage of using the
CSR-01 A320 model lies in having validated infor-
mation about an A320 regarding the propulsion
system, aerodynamics, mass breakdown and per-
formance. The final design concept is compared to
the model with the exception of a changed design
point. Table 1.1 shows the Top Level Aircraft Re-
quirements that are chosen for the design.

Figure 1.1: Operation evaluation of the A320

Table 1.1: Top Level Aircraft Requirements
CSR-01 Polaris
1500

ICAC

2750

Mission Range

[NM]

Alternative

[NM]

200

200

TOFL

[ft]

[m]

Payload

[kg]

13608

13608

Approach Speed

[KCAS]

Passengers

Cruise Mach

[-]

[-]

150

0,78

150 Wing Span Limit

[m]

0,72

Turnaround

[min]

CSR-01 Polaris
33000
33000

2200

138

36

30

2200

138

36

30

1