the disruptive potential of subsonic air-launch

© Telespazio VEGA Deutschland 20/11/2014

Telespazio VEGA Deutschland

THE DISRUPTIVE POTENTIAL OF

SUBSONIC AIR-LAUNCH

12th Reinventing Space Conference

Royal Society, London

18-21 November 2014

David J. Salt - Senior Consultant

© Telespazio VEGA Deutschland 20/11/2014 2

QUESTION: DO WE NEED

BIG LAUNCHERS

TO ENABLE

BIG SPACE ACTIVITIES?

The Disruptive Potential of Subsonic Air-Launch


PRESENTATION OVERVIEW

The Limits to Growth

The Current Space Paradigm & Constraints on Commercial Space

What’s the Problem?... The Space Access Dilemma & Potential for ‘Disruption’

The Case for Subsonic Air-Launch

Benefits of Subsonic Air-Launch & Operational Concept

Benefits of Air Collection & Boost to RLV Performance

Operating Beyond the Limits

LEO Operations & Beyond

Commercial GEO Operations

Conclusions




THE CURRENT SPACE PARADIGM

The current ‘space paradigm’ is stagnating!

space activities are still dominated by government programmes supported by

‘commercial’ contractors

all programmes take longer and cost more than planned

future programmes face cut-backs and/or cancellation due to major constraints on

government discretionary spending


A POTENTIAL FOR GROWTH?

Perspective: The 2012 global space revenue

was $304 billion, which is less than the annual

revenue of one large commercial company

(e.g. Wal-Mart)

World airline revenues in 2012 were $700 billion

Lufthansa’s revenue in 2012 was $39 billion

Question: Without another major government

initiative like Apollo, how can we encourage

and/or create new space markets?



WHAT’S THE PROBLEM?

We have much better supporting technologies than we had 50 years ago,

when Apollo began

manufacturing processes and computer hardware/software have made huge

advances and become cheaper!

Nevertheless, commercial space activities are limited to working with

‘photons’ rather than ‘atoms’ because of the space launch dilemma


THE SPACE ACCESS DILEMMA

Space access is expensive… the price to get into low Earth orbit is on the

order of $10,000/kg because current launcher vehicles are extremely

expensive to operate

Expendables (e.g. Ariane 5) throw away expensive hardware

Repairables (i.e. Shuttle) take too much time/effort to turn-around

Fully reusable launchers with airline-like operations could lower the cost of

space access by at least an order of magnitude (less than $1,000/kg) but…

the estimated cost to develop such vehicles is $10-20 billion

current markets are insufficient to reach flight rates that would justify such a cost

because… space access is expensive!



THE POTENTIAL FOR ‘DISRUPTION’


The current paradigm is very unlikely to overcome these limits to growth,

especially if current launch markets remain ‘inelastic’

lower prices stimulate only limited market growth and, worse still, result in a

significant decrease in total yearly revenue!

One way to overcome this is to radical drop launch prices below $1000/kg,

which can only be achieved via a mature RLV

Another is to stimulate new markets with better elasticity and reduced

performance demands (e.g. sub-orbital flights) that can be serviced by

smaller/cheaper vehicles

Bridging the performance gap between current and new markets will be

critical to realizing this ‘disruptive’ path

This work tries to show how a small subsonic air-launched RLV with

operational flexibility and growth potential could resolve this dilemma



CAVEAT & RATIONALES FOR SUBSONIC AIR-LAUNCH

Subsonic air-launch should be regarded as an enabling capability for a

launch system, not a launch solution in and of itself

the majority of the technology/cost challenge still reside within the rocket

that performs the bulk of the work needed to place any payload into orbit

best thought of as a mobile, high altitude launch facility

It provides performance and operational advantages BUT it does increase

the costs/complexity of the overall launch system

Performance advantages translate into a relaxation of design constraints,

which tend to be better exploited by an RLV than an ELV

relaxation of RLV design constraints make their challenges far more tractable,

realistic and affordable

for ELVs (e.g. Pegasus), these advantages tent to be outweighed by the

drawback unless the prime need is for rapid/flexible launch




THE BENEFITS OF SUBSONIC AIR-LAUNCH

Performance benefits

rocket operations above the dense atmosphere

reduce significantly both drag and gravity losses

enables significant increase in engine specific

impulse (Isp) by using a larger expansion ratio

nozzle that would be over-expanded at lower

altitudes so cause destructive instabilities


Operational benefits

enables operation out of existing airports with reduced launch range constraints

increases launch window flexibility and orbital rendezvous opportunities

up-range launch enables 1st stage to land back at base, minimising ferry flights

Cost & Evolutionary benefits

existing aircraft can be procured/modified at relatively low cost

aircraft can be modified incrementally to increase performance (e.g. better

thrust/weight/performance engines and/or introduction of ACES equipment)



SUBSONIC AIR-LAUNCH OPERATIONS & WINDOWS


Cruise to launch point has major benefits

increases daily launch window opportunities

reduces ‘dog-leg’ for LEO rendezvous

enables atmospheric LOx ‘harvesting’



BENEFITS OF AIR COLLECTION & ENRICHMENT

Use of existing aircraft limits RLV mass and therefore

payload performance to LEO

The gross mass of any launch vehicle using liquid

oxygen (LOx) will be dominated by the LOx mass


Candidate Aircraft External

Mass (Mg)

An-225 200

A380-800F 120

747-100 SCA -911 109

747-400F 140

Dual-fuselage C-5 350

Stratolaunch Carrier 120

oxidiser/fuel rations of 5.2 for liquid hydrogen (LH2) and 2.3 for kerosene (RP-1)

mean that LOx is more than half the RLV gross mass at take-off!

Any method that enables the LOx to be loaded after take-off should offer a

number of significant advantages

increased RLV mass and so payload performance to LEO for any given aircraft

improved safety during ground operations and take-off due to elimination of LOx

Two approaches appear possible

transfer the LOx in-flight from a ‘tanker’ aircraft

utilise the cruise phase to harvest the LOx from the atmosphere

Harvesting LOx via an Air Collection and Enrichment System (ACES) offers

the safer and operational less complex option



ACES CONCEPTUAL DESIGN & OPERATION

ACES generates LOx by ingested air and separating out nitrogen and other

component via heat exchangers and a rotational fractional distillation unit

The heat exchangers use LH2 to super-cool incoming air tapped off the

aircraft’s main engines or drawn in by a dedicated compressor

The resulting LOx is then pumped from the ACES system on the carrier

aircraft into the empty LOx tanks of the launch vehicle during flight




ACES BOOST TO RLV PERFORMANCE

Parametric models of two RLV concepts were developed to investigate the

impact of ACES on LEO payload performance

a two-stage design using LOx/RP on the 1st stage and LOx/LH2 on the 2nd stage

a two-stage liquid design using LOx/LH2 on both stages

RLV mass/performance data was taken from NASA/DARPA & ESA studies

Conservative ACES characteristics were taken from US & European studies




LEO OPERATIONS & BEYOND… “HALFWAY TO ANYWHERE”

Most space station crew

and logistics transport

requirements could be

supported by a subsonic

air-launched RLV

Mass of many GEO and

lunar transport elements

could also be supported

by this same RLV

The vast majority (~80%)

of mass launched to LEO

will be propellant, which

is infinitely divisible!


ISS Servicing Vehicles LEO Mass (Mg)

Soyuz (Government – Russian) 7200

Progress (Government – Russian) 7200

ATV (Government – European) 20200

HTV (Government – Japanese) 19000

Dragon (Commercial – SpaceX) 6000

Cygnus (Commercial – OSC) 4500



COMMERCIAL GEO OPERATIONS

A suborbital air-launched RLV with

4000kg LEO payload performance

can also launch GEO comsats

40% of GEO comsat launch mass is

propellant to go from GTO to GEO

Operational scenario would involve

launch/assembly of a kick stage to

perform LEO to GEO transfer

number of launches depends on

satellite’s Beginning of Life (BoL)

mass

final launch delivers/mates satellite

with kick-stage

Preliminary business case analysis

suggests an RLV with development

costs below $1billion could be a

commercially viable proposition!



Conclusions

CONCLUSIONS

Space activities have so far failed to achieve the great expectations set out

at the dawn of the space age, over half a century ago

Access to LEO (i.e. launch vehicles) is one of the main constraining factors

for in-space developments and operations

A subsonic air-launched RLV could improve access to LEO significantly, in

terms of safety, availability and cost

Such an RLV could support new space infrastructures that would increase

future in-space operations for both exploration and resource exploitation

These developments could be driven by commercial investments, though

there is much scope for governments to foster them in a synergistic manner

Although more detailed analyses are needed in order to confirm these

results, they do tend to suggest that…

We don’t need big launchers to enable big space activities!



THANKS FOR YOUR ATTENTION…

… ANY QUESTIONS?



SUPPLEMENTARY SLIDES





ACES CYCLE DESIGN & EXPERIMENTAL TEST HARDWARE


Supplementary Slides

ACES SCHEMATIC




NASA/DARPA DESIGN CONCEPTS (PD-2 & PD-3)




EVOLUTIONARY STEPS FOR A ‘BIMESE’ RLV




RLV SCALING RELATIONSHIPS

x




SELECTION OF EXTERNAL CARRIAGE AIR-LAUNCH CONCEPTS

(EXCLUDES TOWED OR INTERNAL CARRIAGE)


Config. Concept Name Designer/Year Air-launch Vehicle Propellant Reusable Payload

Cap

tiv

e o

n T

op

Boeing AirLaunch USA/1999 747 Solid No 3.4t

Interim HOTOL UK/1991 An-225 LH2/LOx Fully 7.0t

MAKS-M USSR/1989 An-225 RP-1/LH2/LOx Partly 5.5t

MAKS-OS USSR/1989 An-225 RP-1/LH2/LOx Partly 8.3t

Pegasus II USA/2011 Stratolaunch Solid+Cryo No 6.1t

Saenger II Germany/1991 Mach 4.4 turbo-ramjet LH2/LOx Fully 9.0t

Spiral 50-50 USSR/1965 Mach 6 turbo-ramjet RP-1/LOx Partly 10.0t

Teledyne-Brown USA/1986 747 LH2/LOx Fully 6.7t

Cap

tiv

e

on

Bo

tto

m Global Strike Eagle USA/2006 F-15 Solid No 0.3t

Pegasus USA/1990 L-1011 Solid No 0.5t

Yakovlev HAAL USSR/1994 Tu-160 Solid No 1.1t



AIR-LAUNCH MODEL INFO.


Wing & TPS Mass: Scales directly with materials factor (S) and the change,

with respect to the baseline, in the sum of Fuselage, Tank, Systems, and

Engine masses (Ms3 + Ms4 + Ms5 + Ms6).

Fuselage Mass: Scales directly with materials factor (S) and the change, with

respect to the baseline, in the propellant tank mass (Ms4).

Tank Mass: Scales directly with materials factor (S) and the change, with

respect to the baseline, in the propellant mass (Mf) raised to the power of 2/3.

Systems & Engine Mass: Scales directly with the change in the propellant

mass (Mf), with respect to the baseline.

RLV Design & Mission

1 Baseline mission delta-v to 400km LEO = 7820 m/s

2 Delta-v loss: 1750 m/s from sea-level; 850 m/s from 10km

3 Existing rocket engines (e.g. Merlin 1C & RL10A-4-2)

4 Oxydised/Fuel ratio: 2.28 for LOx/RP; 5.24 for LOx/LH2

5 Isp: 450s @10km for LOx/LH2; 300s @10km for LOx/RP

6 Current available structural materials (i.e. TRL 6+)

7 TPS mass: 5% Booster dry mass; 20% Orbiter dry mass

8 Wings + Empennage + body flap: 7% dry mass

ACES Characteristics [RD.10]

1 LOx collection plant (LCP) mass / volume = 4Mg / 6m3

2 Collection Ratio (CR) = 2.0 (i.e. 1kg LH2 => 2.0kg LOx)

3 LOx collection purity = 90% (i.e. 10% N2)

4 LOx collection rate = 9 kg/sec

5 Isp = 292s @10km for LOx/RP with 90% purity LOx

6 Isp = 435s @10km for LOx/LH2 with 90% purity LOx

Separation Mach number (Mn) = 12 Air-Launched +ACES Air-Launched +ACESMaterials density scaling factor (S) [%] 1.00 1.00 1.00 1.00

TSTO Booster Details TSTO Orbiter Details

Specific Impulse (Isp) [sec.] 450 435 Specific Impulse (Isp) [sec.] 450 435

Rocket equation factor (R=Exp(dV/Isp/g) 2.5968 2.6836 Rocket equation factor (R=Exp(dV/Isp/g) 2.7448 2.8421

TSTO Gross Mass (MTg=MBp+MBs+MBf) [kg] 138576 200848 Orbiter Gross Mass (M0g=MOp+MOs+MOf) [kg] 34857 48908

Booster Dry Mass (MBs=SUM(MBs1:MBs6)) [kg] 18508 25933 Orbiter Dry Mass (MOs=SUM(MOs1:MOs6)) [kg] 5379 7139

Wings Mass (MBs1) [kg] 1414 1981 Wings Mass (MOs1) [kg] 615 817

TPS Mass (MBs2) [kg] 1014 1421 TPS Mass (MOs2) [kg] 1090 1446

Fuselage Mass (MBs3) [kg] 3390 4399 Fuselage Mass (MOs3) [kg] 1251 1588

Tank Mass (MBs4) [kg] 3509 4555 Tank Mass (MOs4) [kg] 1508 1914

Systems Mass (MBs5) [kg] 2020 2987 Systems Mass (MOs5) [kg] 677 968

Engines Mass (MBs6) [kg] 7162 10590 Engines Mass (MOs6) [kg] 854 1222

FSSC-16 Defined Propellant Mass (MBf) [kg] 85211 126006 FSSC-16 Defined Propellant Mass (MOf) [kg] 22158 31700

Booster Payload (MBp=MOg, Orbiter Gross Mass) [kg] 34857 48908 Resultant TSTO Payload (MOp) [kg] 7320 10070

Booster delta-V loss (LdV) [m/s] 850 850 Orbiter delta-V loss (LdV) [m/s] --- ---

Booster delta-V (BdV) [m/s] 3363 3363 Orbiter delta-V (OdV) [m/s] 4457 4457

ACES Details TSTO System Details

LOx fraction of TSTO gross mass 65% 66% Total Mission Delta-V [m/s] 8670 8670

Total LOx propellant [kg] 90165 132436 TSTO Dry Mass (MTs=MBs+MOs) [kg] 23887 33072

LCP mass [kg] --- 4000 TSTO Gross Mass (MTg=MTs+MBf+MOf+MOp) [kg] 138576 200848

LH2 for ACES [kg] --- 66218 TSTO Gross Mass without LOx [kg] --- 68412

ACES 'kit' Mass [kg] --- 70218 TSTO Gross Mass without LOx + ACES [kg] --- 138630



RLV BUSINESS MODEL PARAMETERS


Satellite Mass

(kg)

Total No.

(2013-2022)

Annual Average

(2013-2022)

% of

Total

Below 2200 29 2.9 13%

2200 to 4200 62 6.2 27%

4200 to 54000 46 4.6 20%

54000 and

above

91 9.1 40%

Total Forecast 228 22.8 100%

Business Parameter Value range

Total R&D investment $500-1000 million

Fleet size 3 operational vehicles

Price per flight $10-20 million

Variable cost (per flight) $2-10 million

Fixed annual operating cost $40 million

Income tax rate 40%-60%

Interest rate 10% (for debt finance)

Annual flights (fleet max.) 100

First commercial launch 4 years after start



STEPS TOWARDS A NEW SPACE PARADIGM


Timeframe Future Steps Impacts

Proof of Concept

(2012-2018)

COTS payload services to ISS (~2012) MODEST: Increased microgravity

experimentation

Frequent reusable suborbital services

for tourist passengers (~2016)

SIGNIFICANT: Rapid flight vehicle

turn-around and passenger training

COTS crew rotation to ISS (~2018) MODEST: Improved human in-situ

servicing and support

Concept Maturation

(2018-2020)

Commercial space station & ELV

support (~2020)

SIGNIFICANT: Increased human in-

situ servicing and support

Air-launched RLVs for ISS cargo and

GEO satellite launch (~2020)

VERY SIGNIFICANT: Increased

satellite missions and space

infrastructure development

Air-launched RLVs for passenger

services to ISS and commercial

stations (~2023)

VERY SIGNIFICANT: Increased

human in-situ activities supporting

complex space developments

In-orbit propellant depots for crewed

exploration missions (~2025)

VERY SIGNIFICANT: Enables deep

space exploration missions and

exploitation of space resources

the disruptive potential of subsonic air-launch

Presentations & Public Speaking