Evaluation of Future Ariane Reusable VTOL Booster stages

> Etienne Dumont > IAC-17 – D2.4.3 > 2017_09_27 www.DLR.de • Chart 1

Etienne Dumont1*, Sven Stappert1, Tobias Ecker2, Jascha Wilken1, Sebastian Karl2, Sven Krummen1, Martin Sippel1 1Department of Space Launcher Systems Analysis (SART), Institut of Space Systems, Bremen, Germany 2Department of Spacecraft, Institute of Aerodynamics and Flow Technology, Gottingen, Germany

*Etienne.dumont@dlr.de

IAC 2017

27th September 2017

Adelaide, Australia

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Introduction The launcher market is changing quickly, many new launchers will enter on the market in the coming years: • Ariane 6, H3, Falcon Heavy, Vulcan, New Glenn, GSLV Mk. III, … New solutions have to be implemented to guarantee competitiveness: reusability or new propellant could be some of them DLR is performing a systematic analysis of different first stage return systems: • Fly Back • In Air capturing • Return to Launch Site • Down-range Landing

Propellant combinations considered: LOx/LH2, LOx/LCH4, LOx/LC3H8 and sub-cooling

www.DLR.de • Chart 2 > Etienne Dumont > IAC-17 – D2.4.3 > 2017_09_27

winged

ballistic

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Overview

• Assumptions

• Trajectory overview

• Validation

• Preliminary design (iterations 1 and 2)

• Aerothermal analysis and structure temperature evaluation

• Conclusions

www.DLR.de • Chart 3 > Etienne Dumont > IAC-17 – D2.4.3 > 2017_09_27

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Assumptions

• Launch from CSG

• Sizing mission: 7 tons into GTO (+ 500 kg project margins)

• TSTO architecture (generic launcher)

• Same engine in both stages (longer nozzle for the upper stage)

• Three stagings determined by fixed ∆V (6.6 km/s, 7.0 km/s and 7.6 km/s) of the upper stage

• Return to launch site (RTLS) and down range landing (DRL) considered

• Dry mass:

• 1st iteration pre-assumed structural index • 2nd iteration structural preliminary sizing + margins

www.DLR.de • Chart 4 > Etienne Dumont > IAC-17 – D2.4.3 > 2017_09_27

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RTLS and DRL www.DLR.de • Chart 5 > Etienne Dumont > IAC-17 – D2.4.3 > 2017_09_27

Examples of RTLS (return to launch site) and DRL (down range landing) trajectories

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Validation: Falcon 9 flight simulations • Example of the SES-10 and the NROL-76 flights

www.DLR.de • Chart 6 > Etienne Dumont > IAC-17 – D2.4.3 > 2017_09_27

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NROL-76 (RTLS LEO)

NROL-76 first stage

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Preliminary design • Propellants

• LC3H8 has a large densification potential

www.DLR.de • Chart 7 > Etienne Dumont > IAC-17 – D2.4.3 > 2017_09_27

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Normal boiling point Near triple point

• Engines • 1st stage nozzle extension chosen to avoid

flow separation at landing at low thrust level

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Preliminary design: 1st iteration • Main results

• RTLS: all solutions require very large stages, not very interesting for TSTO flying into GTO

• DRL: optimum engine number strongly dependent on propellant

• DRL: lower stage size is not decreasing with increasing upper stage ∆V

• DRL: LC3H8 launchers have some advantages over LCH4

www.DLR.de • Chart 8 > Etienne Dumont > IAC-17 – D2.4.3 > 2017_09_27

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1st stage 2nd stage Payload

LOx/ LC3H8LOx/ LH2 SCLOx/ LH2 GGLOx/ LCH4 GG

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Preliminary design: 2nd iteration (DRL) • Main results

• Strong mass decrease due to light upper stage • LCH4 configuration slightly larger than the LH2 one in

volume and double in mass

www.DLR.de • Chart 9 > Etienne Dumont > IAC-17 – D2.4.3 > 2017_09_27

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H298H77 C648C142

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2nd stage ascentpropellant

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1st stage ascentpropellant

1st stage dry mass

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Aerothermal analysis www.DLR.de • Chart 10

• Aerothermal database • Several RANS calculations at different

trajectory points and fixed uniform wall temperatures were performed.

• Numerical domain and boundary conditions • Exhaust gas composition was determined

from equilibrium and held frozen. • Zero angle of attack • Uniform wall temperatures (300 and 400 K) • Internal nozzle wall temperature set to

1000 K

> Etienne Dumont > IAC-17 – D2.4.3 > 2017_09_27

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Aerothermal database

• Plume flow development • Plume extension is strongly dependent on altitude. • Full immersion of vehicle at the beginning of retro-

propulsion. Partial immersion at the end of the maneuver.

• After retro-propulsion heat flux peaks on lower skirt and nozzle region.

www.DLR.de • Chart 11 > Etienne Dumont > IAC-17 – D2.4.3 > 2017_09_27

After retro-propulsion

End of retro-propulsion

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Surface temperature evolution www.DLR.de • Chart 12

• Aerothermal database and wall temperature estimation: • Wall temperature at t = 0 s is estimated at 300 K • Lumped mass, 0D heat transfer model (wall thickness non

uniform along the streamwise axis)

> Etienne Dumont > IAC-17 – D2.4.3 > 2017_09_27

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Conclusions www.DLR.de • Chart 13 > Etienne Dumont > IAC-17 – D2.4.3 > 2017_09_27

• RTLS • TSTO vehicles able to launch 7 tons to GTO have a low economic relevance

• DRL

• TSTO performing GTO missions have reasonable sizes and masses • LOx/LH2 versions are twice as light as LOx/hydrocarbon versions • The LOx/LCH4 versions are the bulkiest of all, the LOx/LC3H8 is the less bulky • Densification has a large potential for improvement, especially for propane • Larger upper stage ∆V leads to larger lower stage • Most heat loads on the sidewall are taking place during the retro-propulsion, the temperature

increase can get high in low thickness structures place in the bottom of the vehicle

• Main goal is to compare costs but it is tricky due to a lack of knowledge of the operational costs. • Demonstrators are required