High Speed Civil Transport: An Analysis of the Economic Viability of a Supersonic Business Jet

Analysis Team:

Tianchen CaiJames Christensen

Michael LopezHaniel Roman

The report presents an economic feasibility analysis of several current supersonic business jet (SSB) design proposals. Of the potential supersonic designs, a supersonic business jet was chosen as the most likely option to produce an economically viable form of transportation. Potential markets and customer requirements are explored based on current business jet market behavior and surveys. Systems engineering tools such as an Affinity Diagram, Tree Diagram, Prioritization Matrix, Quality Function Development (QFD), Morphological Matrices, and TOPSIS tools are used to determine the economic viability of a SSBJ against currently available subsonic designs and a conclusion on the business case for a SSBJ is made. Each of these tools provided insight into the possibilities for a supersonic design as well as the options for improving the performance of supersonic flight and reducing the cost to produce an optimized, final design. After the final TOPSIS analysis, it was determined that using current technology, a supersonic business jet design was not more profitable than the baseline for this aircraft, the Cessna Citation X subsonic business jet. Therefore, from a purely economical standpoint, it would not be profitable at this current point in time to produce a supersonic business jet in today’s market.

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I. Introduction

Proposals for a civilian supersonic transport (SST) aircraft have existed in several forms since at least the 1950s.

However, government subsized SST programs in the United States, Britian, France, and the USSR/Russia combined

have only produced two operational SST aircraft. The Russian Tu-144, which saw limited service from 1975 until

1978, was largely viewed as a politically driven design and was never a commercial success. The Concorde aircraft

which was jointly developed by the British and French aerospace industries became operational in 1976 and saw 27

years of service flying transatlantic routes between the United States and Europe. While the Concorde was profitable

for the airlines that employed it, the advent of larger and cheaper to operate wide body subsonic airliners ultimately

led to its retirement. The revenue generated from the Concorde also never came close to covering its development

costs over its lifetime.1

Government and civilian funded programs for a SST have gone through many iterations since the success of the

Concorde program in the 1970s. However, most proposals have stagnated or been dropped due to lack of a business

case for their continued development.2 This report seeks to quantitatively analyze several SST proposals and identify

which could proposals could be economically viable in today’s market.

II. Motivation and Objectives

Despite numerous SST proposals there has been no operated commercial supersonic aircraft in service since the

Concorde’s retirement in 2003. The numerous technological advances in engine design and aerodynamics since the

Concorde’s original designing in the 1960s suggests that the economics of a SST be reevaluated for the current

market. Table I shows a specification summary of supersonic business jet (SSBJ) design proposals that have been

presented in the last 25 years as complied by Leibhardt and Lutgens. Though larger scale (Concorde sized) SST

have been proposed, in order to limit the scope of this investigation only small “business jet” class SST proposals

were evaluated for economical feasibility.

Table I: Proposed Supersonic Transport Designs

Aerio

n SB

J

Gul

fstr

eam

Q

ST

HIS

AC-A

HIS

AC-B

(N

LF)

HIS

AC-C

Year Proposed 2010 2009 2009 2009 2009Estimated Unit Cost 80M 80M - - -

Design Range 4000 4000 4000 5000 4000Design Cruise Mach 1.5 1.6 1.6 1.6 1.8

Typical Passenger Capacity 8 8 8 8 6Thrust (kN) 174 294 220 313 292.6

1 Leibhardt, Lutgens2 Leibhardt, Lutgens

2

Max Takeoff Weight (t) 40.8 69.4 51.5 60.5 53.3

Most SSBJ designs can be lumped into either of two catagories based on the technology they intend to employ.

The first are the natural laminar flow designs such as the Aerion SBJ which seek in drastically reduce supersonic

drag using slender wing designs. The goal behind these designs is to significantly improve fuel efficiency of the

aircraft while at supersonic cruise to reduce operating costs. The second group seek to utilize some sort of “quiet

boom” technology to dramatically decrease the amplitude of the sonic boom created by the aircraft. The hope with

quiet boom technologies is to eliminate the effect of the sonic boom on the ground and allow overland supersonic

travel.

III. Market Research

A. Business Jet Uses and Customer Identification

The National Business Aircraft Association (NBAA) identifies several advantages of business jet class aircraft

versus airline travel in its annual Fact Book including:

Saves employee time.

Increased traveler productivity, safety and security.

Ability to reach multiple destiantions quickly and efficiently

Ability to access communities with little or no airline service.

Scheduling predictability and flexibility.

Figure 1: Business Jet Advantages

Over 85% of users of business jet aircraft are small to medium size companies many of whom are based in

communities that have reduced or restrictive airline service.3 Other uses of business jets include governments,

charter or fractional ownership organizations, and private users.

3 NBAA Factbook

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The SSBJ at first glance seems like it would be well suited to the business jet user, in particular in providing

readily available and time efficient travey. A survey conduction by Leibhardt and Lutgens polled potentional SSBJ

users about their current business jet use and the minimum characteristics of a SSBJ they would want in order to

consider purchasing one. A summary of there customer requirement is shown below in Table II below.

Table II: Customer Requirements

Current Uses: Desired SSBJ Characteristics:

Flown between 300 - 600 hours per year 10 to 13 seats

40% of flights are greater than 3000 NM 5000 nm range

For 80% of long flights 7 to 9 seats is sufficientWilling to spend a ~50% cost premium for

a reduction in travel time of 50%

Average overwater departures less than 50% Overland travel at supersonic speeds

The most restrictive of these desired characteristic is the desire for highspeed overland travel. Though it is

possible for current bans on overland supersonic travel to be lifted as quiet boom technologies mature, the current

reality is that a SSBJ would only be useful in less than 50% of the flights undertaken by current users.

The limitations on overland travel and high initial costs make the market for purchase of SSBJs by corporate

entitities very low.4 However, a possibile market might exist with so called fractional ownership organizations since

the initial costs are shared by the cooperative group’s members.

For our analysis we have assumed the route flown by the aircraft is almost entirely over water (similar to the

Concorde’s transatlantic route) to allow for fair comparison with subsonic business jets. This assumption is a valid

one as it follows that the primary advantages of a SSBJ is its speed and this speed advantage is going to maximized

more over the long haul routes used for transocean travel.

B. Economic Justification for Supersonic Flight

The high initial costs and increased operational costs of proposed SSBJ designs place it at a disadvantage to its

subsonic competitors. (The Aerion SSBJ’s target purchase price of 100 million dollars5 is nearly five times the

purchase of the Cessna Citation X.) Even at the maximum expected yearly flight rates a SSBJ would not be able to

compete with a subsonic aircraft in terms of operational costs versus flight time. In order for target customer to

realize the potential of a SSBJ the speed advantage and the associated benefit to the travel need to be quantified.

Analysis done by Chudoba et al. shows that one want to quantify this benefit is to factor in the salary of the

passengers on board the aircraft. In effect, every hour that the employee is not on the aircraft is another hour where

their salary is directly providing benefit to the company and constitutes a cost savings.

Chudoba’s analysis assumed a 6000 NM round trip flight which would take a subsonic aircraft about 32 hours to

complete. A supersonic aircraft would be able to perform the same trip in approximately 14 hours. The results are

shown in Figure 2 below.

4 Leibhardt, Lutgens5 Aerion Corporation’s website

4

Figure 2: Cost per Flight vs. Executive Annual Compensation

A clear benefit is seen for a SSBJ when transporting individuals with high levels of compensation which a

breakeven point at about $300,000 per year.

IV. Affinity Diagram

In order to narrow the potential design options down towards one finalized design, the first step is to create an

affinity diagram. This diagram displays the goals, potential design options, project assumptions, and predicted

obstacles for the project. The goals for this design align with the goals set forth for the original design of the

Concorde: high speed, long range transportation for individuals willing to pay a slighter higher price than that of

regular, commercial transportation. For this design, the Concorde was assumed to be a baseline, a study period of 30

years was used, the design was evaluated for a range of 4,500 miles, and the aircraft was assumed to use Jet A1 or

similar fuel to minimize cost and maximize availability. The issues that were predicted to be encountered during this

design were sufficient passenger capacity, the fuel expensive of using supersonic capable engines, the high

maintenance cost of the proposed design, current conflicts with domestic and international regulations on supersonic

travel, and the high cost of ensuring that the vehicle would be safe at all times. The result of this preliminary

analysis is shown in the affinity diagram in Figure 3 below.

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Figure 3: Affinity Diagram

The result of creating this affinity diagram was the selection of a supersonic business jet as the goal of the

economic analysis for this project. The supersonic business jet was chosen based on the combination of the current

market for high speed subsonic business jets and the previously explored market of supersonic commercial travel

through vehicles like the Concorde. A supersonic business jet is the most likely option to meet all of the desired

requirements and goals while minimizing the previously predicted issues with the design.

V. Tree Diagram

The tree diagram was essential in putting the ideas of the proposal in motion. We first decided our high level

goal which was the Supersonic Aircraft designed to compete with subsonic airtravel. It was then broken down into

the details/subgoals being “Good Performance” and “Good Price”, looking to optimize both sides of the

development the Supersonic Aircraft. Good performance was related to optimizing engineering performance criteria

while good price was taking customer requirements into account. Subgoals were identified for the engineering

criteria and customer requirements. The engineering requirement rounded out to good maneuverability, good range

and good speed, while for the customer requirements rounded out to affordable manufacturing, meaning following

the customer requirements while being as cost effective as we can. The final heading of tasks/options finally listed

the details of the details/subgoals, being that they had to fulfill level 1 flight qualities, complete transatlantic travel

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and attain supersonic flight while affordable manufacturing went into such categories ass maintenance and fuel

costs.

Figure 4: Tree Diagram

VI. Prioritization Matrix

The prioritization matrix is a tool to estimate the customer’s requirements’ relative weights between each other.

Each raw requirement will compare with every column requirement except itself. The score weighs the relative

importance of one requirement over another and is scored on a from 0.1 to 10. A score greater than one means that

the requirement in the row has a higher relative importance than the requirement in the column, a score less than one

means that the requirement in the row has a higher relative importance than the requirement in the column, and a

score equal to one means that the two requirements are equally important. The prioritization matrix created for this

project is shown below in Table III.

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Table III: Prioritization Matrix

crui

se r

ange

crui

se s

peed

oper

atin

g co

st

com

fort

flex

ibil

ity

sale

pri

ce

capa

city

prod

ucti

vity

Sum

Wei

ghte

d P

erce

ntag

e

cruise range 2 2 2 1 0.5 2 0.5 10 13.3%

cruise speed 0.5 0.5 1 0.2 0.5 1 0.2 3.9 5.2%

operating cost 0.5 2 2 0.5 2 2 1 10 13.3%

comfort 0.5 1 0.5 0.5 2 2 1 7.5 10.0%

flexibility 1 5 2 2 2 5 1 18 24.0%

sale price 2 2 0.5 0.5 0.5 2 0.5 8 10.7%

capacity 0.5 1 0.5 0.5 0.2 0.5 0.5 3.7 4.9%

productivity 2 5 1 1 1 2 2 14 18.6%

After the prioritization matrix was completed, the requirements were reorganized based on their weighted

percentages. Table IV below shows the requirements organized from the most important to the least important. For

this project, the flexibility of the aircraft was determined to be the most relatively important while the capacity of the

aircraft was determine to be the least relatively important.

Table IV: Prioritized Requirements

Requirement Weighted Percentage

Flexibility 24.0%

Productivity 18.6%

Cruise Range 13.3%

Operating Cost 13.3%

Sale Price 10.7%

Comfort 10.0%

Cruise Speed 5.2%

Capacity 4.9%

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VII. QFD

The QFD is based on the previous research results from Affinity, Tree Diagram, and prioritization matrix. The

QFD gives relationships between customer’s requirements and engineering requirements. It also shows the

correlation between different engineering requirements. Once all the relations are clear, the QFD will automatically

return relative risk weightings for each engineering requirements which are very important for following analysis.

Figure 5: House of Quality

A. Correlation matrix and relationship matrix

The correlation matrix describes whether there is a positive or negative effects between each engineering

requirements. Plus sign means positive effect between two requirements. Oppositely, Minors sign means negative

effect between two engineering requirements. Not every requirement has correlations with others. Therefore, there

will be a blank if two requirements are independent. There are some significant negative relations in our QFD.

Almost every performance and luxury requirements have negative effects on production cost. This is a very useful

information which tells us if the company wants to save money on production cost, they have to cut some features

from performance or luxury designs.

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Figure 6: Correlation Matrix

The relationship matrix describes whether there is strong or weak relations between a customer’s requirement

and an engineering requirement. For example, TSFC and lift/Drag ratio very relative to the cruise range. So, if

customer asked a long cruise range, the TSFC and Lift/drag ratio will have strong relationships with this certain

customer’s requirement. A solid red spot states there is a strong relationship between them. For other cases, a circle

means moderate relationships, and a down triangle means weak relationships. Like the correlation matrix, there

could be not relationships between two requirements.

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Figure 7: QFD Relationship Matrix

When all the relationships are determined, the QFD will return risk weightings for each engineering requirements.

Those numbers show how possible a design may not satisfy customers. Larger risk weighting requires engineers be

more careful when they are designing for that requirement. Some conclusions like, maintenance cost(23%) takes the

first place which should be treat most carefully on designing. Lift/Drag ratio (16%) and maximum takeoff weight

(13%) are in second and third place. Also, both turnover time and cruise ceiling (1%) have least risk need to be

worried.

B. Baseline

The baseline was created through research based on competitors of a supersonic business jet environment in

today’s age. The main baseline was the Cessna Citation X, the fastest alternative of subsonic travel available in use

currently. The other baselines were other “competing” supersonic aircraft currently solely in the research and

development phase, the Aerion AS2 and the Gulfstream X-54. For the Citation X, we were able to locate the data

from Cessna sources, however with the Aerion AS2 and the Gulfstream X-54, we need to base data on estimates of

similarly developed aircraft in the same time frame. Being all theoretical information however, the variance in the

data will greatly impact the results of the analysis we provided such as QFD weighting criteria and TOPSIS

distances. The final data pulled into a reasonable margin which allowed for sufficient estimation of criteria.

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Figure 8: QFD Baseline

VIII. Morphological Matrices

To develop the Morphological matrix, first we concisely defined the problem so that we could develop

parameters for the solution. Next, we identified all of the parameters that would influence the solution, making sure

that every option was at least examined, parameters included but were not limited to: cruise speed, engine type,

navigation system, and number of seats. We researched many viable alternatives that fell into the case of a

supersonic business jet which would then describe the aspects by which the alternatives would be defined, such as

Mach numbers for cruise speed; turbofan, turbojet, ramjet for engine type and 6-16 number of seats, so we could at

least have tangible alternatives, not minding if they were sub-optimal.

To organize the ideas, we consolidated the parameters into categories, such as flight parameters, engine, body,

wing, passive safety, active safety, luxury, and productivity. We then developed four super categories: performance,

structure, safety and customer appeal, where performance, structure and safety adhered to the engineering criteria

such as flight parameters, while customer appeal would satisfy customer requirements. After having a considerable

number of alternatives, we evaluated each of the alternatives against the given customer metrics and engineering

criteria to be able to optimally address the problem.

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Figure 9: Morphological Matrix

Aspects within the morphological matrix were held constant since they had no noticeable impact on the design

optimization between each of the final alternatives, such as in the navigation system category where global

positioning satellite superceded all other alternatives and would be the optimal solution for each option, while the

luxury category was defined by the customer’s own tastes, so in our final description of the options those categories

were eliminated. In aspects like engine type, engine number, passenger capacity, were highly dependent on

performance design metrics and were selected based on being optimally suitable solutions, which resulted in three

options, the baseline and the two alternatives.

Table V: Morphological Matrix Comparison

Baseline Option 1 Option 2Citation X Aerion AS2 Gulfstream X-54

Cruise Speed Mach 0.9 Mach 1.6 Mach 1.4Cruise Altitude 51,000 ft 51,000 ft 64,000 ft

Range 3200 nm 2500 nm 4500 nmNumber of Engines 2 3 2

Engine Type High Bypass Turbofan Low Bypass Turbofan Low Bypass TurbofanPassenger Capacity 12 12 10

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IX. TOPSIS

The TOPSIS analysis is the last step to make final decision from those alternatives. In this case, there are three

alternatives which are Citation X, Aerion AS2, and Gulfsteam S-21. Citation X is a mature transonic business jet

model. Aerion AS2 and Gulfstream S-21 are both under development SSBJ model. TOPSIS compares alternatives

via different criterions which are obtained from QFD. Every criterion takes a weighting which also comes from

previous QFD results. Apply actual data values of alternatives under different criterions from researches can get

more accurate result from TOPSIS analysis. Since there is not mature supersonic business jet model in current

market, only limited performance data can be obtained from some under development SSBJ projects. For those

criterions without any reliable resource to support, assumptions will be made based on our knowledge and indirect

researches. There is another analysis skill is used for TOPSIS analysis. For some criterions which have negative

effects to our goal, use reciprocal of data values instead of its original values. For example empty weight of citation

X is 9000Kg. 1/9000kg is used in comparison instead of 9000kg.

ThrustTSFC

Lift/D

rag Ratio

Empty W

eight

Passenger/C

argo Weight

Maximum Take

off Weight

Turnaround Time

Cruise Ceilin

g

Noise Reducti

on

Communications A

menities

Production Cost

Refueling Cost(

per unit)

Maintenance Cost

Purchase

Price

0.00%

5.00%

10.00%

15.00%

20.00%

25.00%

1.81%

4.19%

16.27%

1.92%

7.04%

19.07%

1.31% 1.17%

2.82%

11.87%

1.94%

4.85%

23.18%

2.58%

Figure 10: Engineering Characteristics

After several calculations, the TOPSIS analysis returns the closeness to ideal solution for all alternatives. The

higher value there is, the alternative is closer to the ideal solution. From our TOPSIS analysis result, Citation X

becomes final winner. And the gulfstream S-21 is closer to ideal solution than Aerion AS2 as supersonic business

jet.

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Citation X Aerion AS2 Gulfstream-S210

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.601802626178337

0.322180848698408

0.401111761231459

Figure 11: TOPSIS Analysis Result

X. Conclusion

This report presented a systems engineering analysis of SSBJ designs and compared their economic

competitiveness with subsonic competitors. TOPSIS analysis showed that the low boom Gulfstream SSBJ design

was the best of the supersonic aircraft evaluated but its performance for the given customer was still behind that of

currently aviable subsonic designs. Our market research and cost analysis show that the market for a SSBJ is most

likely very weak and is not well defined. As a result our data suggests that a SSBJ is not economically feasible with

current technology, restrictions, and market conditions. It is possible that as quiet boom technology matures and

allows for overland supersonic travel to be possible that market conditions will become favorable.

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