hydrogen fuelled pre-cooled jet engines bond...hydrogen fuelled pre-cooled jet engines origins early...
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A Presentation to the Royal A Presentation to the Royal Aeronautical SocietyAeronautical Society
3 June 20083 June 2008Alan Bond, Managing Director
Reaction Engines Ltd
Hydrogen Fuelled Hydrogen Fuelled PrePre--Cooled Jet Cooled Jet
EnginesEngines
Can We Consider Single Stage Vehicles?Earth is marginally too big to admit an effective SSTO rocket with near term materials technology, discounting the use of ozone or fluorine.
Use must be made of the lower atmosphere for both its chemical potential and reaction mass.
(Nuclear propulsion is the subject of a different lecture!)
Characteristics for Commercial Operations (1)•• Reusability:Reusability:
reduced cost per flight by amortising production cost over 200 flights.
•• SingleSingle--stage:stage:
reduced development and operating costs relative to multi-stage vehicles.
•• UnUn--piloted:piloted:
reduced mission control, relaxed safety during development, increased payload. dedicated accessory passenger module for payload bay.
Characteristics for Commercial Operations (2)Abort capability:Abort capability:
abort to launch site with up to half engines failed.
flight critical systems redundant to single point failure.
User friendly operations:User friendly operations:
simple ground handling and automatic checkout.
low maintenance through robust TPS and long life engines.
containerised payload system.
ReRe--entry crossentry cross--range:range:
high hypersonic L/D to improve return opportunities to launch site.
Environmental impact:Environmental impact:
benign propellants, ‘low’ engine noise, no orbital debris.
SKYLON is a matureproject study supportedby extensive universityand industry input.
Hypersonic wind tunnel tests at QinetiQ, Farnborough
Mn = 9.5Courtesy of QinetiQ
Abort CharacteristicsFull return to base envelope for single point abortable failures.
Full take-off abort envelope.
Aerodynamically controllable with one nacelle inoperable in airbreathing ascent.
Mach 3 ramjet return cruise mode for early rocket abort.
‘Once Around’ mode for late rocket abort.
Fully redundant RCS and OMS systems.
Cooler
Compressor Turbine
Thermodynamic Cycle
Heat Sink
Air intake
Liquid hydrogen
Combustor
2nd Cycle
Precooled Engine Cycle
Some SABRE Parameters
Area ratio 100
Airbreathing combustion pressure 102bar (nominal)
Rocket combustion pressure 145bar (max)
Cycle pressure ratio 4.5:1
Compressor pressure ratio 140
Equivalence ratio 2.8
Veff at Mach 5 16,000 m/s (cf. 46,000 ideal)
Oxidiser cooled combustion chamber
Heat Exchanger Manufacturing Development
Supported by a DTI SMART Award
Brazed Joints
0.88mm x 30µm wall tube
Pre-Cooled Gas Turbine Test
Demonstrate real heat exchanger construction and tube size on a test with 9% flow and area.
Objective
Brussels-Sydney: Bering Straits route
Leg 1: Brussels-Nome (Alaska) 7176 km
Leg 2: Nome - Sydney 11,552 km
Total journey 18,732 km
4.7 hours @Mach 5 cruise (assuming supersonic overflight of Bering straits)
Scimitar Rev.1 Main Cycle Parameters at Mach5
1320K 635K
853K
999K
291K
843K
989K
610K
861K2627K
200bar
132bar
50.8bar
2.4bar3bar
18bar
200bar
HX3
He turbine
Two spool compressor
Fan & hub turbine
Preburner
Core engine combustor
Bypass combustor
Scimitar Schematic
Precooler
Silicon Carbide manufacturing research
Successful extrusion of rectangular strips 600mm long (or more).
Relatively good control of channel dimensions and wall thickness.
‘Green’ extruded strips require drying mould to control profile.
Removal process required for internal silicon beads that form during reaction bonding process.
Some Scimitar Parameters
Subsonic mode operation below Mach 2.5
Precooled above Mach 3 at inlet 635K
Mach 5 ER = 0.8, Veff = 44,000m/s
Mach 0.9 ER = 0.075, Veff = 96,000m/s
Compressor pressure ratio 4
Fan pressure ratio 1.8
In Summary:-From the Von Braun Studies of the early 1950s, over half a Century has elapsed and a reusable space transportation system seems as remote as ever.
40 years have passed since Phil Bono of Douglas showed that a single stage to orbit low cross-range vehicle is credible, given high performance rocket engines and structures, which we now have.
It is now 20+ years since British Aerospace and Rolls-Royce carried out the HOTOL study, indicating the possibility of realising a high cross-range single stage vehicle.
In Summary:-Today the spacefaring nations of the World are planning a new generation of launchers based on ‘more of the same’. In addition the World is back to subsonic civil transport.
The aerospace industry and the aerospace establishments are obsessed with Scramjets which will keep them in research funds for another generation.
The precooled engine is virtually here. It is adequate to Mach 5 at which we can do a very great deal to advance the utility of space and the quality of life through improved transportation. Lets get on with it!