The document discusses ramjet engines and provides several key details: 1) Ramjets rely on forward speed to compress incoming air rather than using moving parts. They achieve thrust by accelerating exhaust gases to a higher velocity than the inlet air. 2) Ramjet performance depends on the increase in stagnation temperature across the combustor. Specific thrust and efficiencies increase with higher flight Mach numbers. 3) Ramjets have powered missiles like the Bomarc, which used liquid and ramjet engines. Hypersonic experimental vehicles like HyFly are being developed with dual-mode ramjet/scramjet engines.

1. RAMJET ENGINE
By
S.VELMURUGAN
AP/AERO

2. RAMJET BASIC OPERATION
• Ramjet has no moving parts
• Achieves compression of intake air by forward speed of vehicle
• Air entering the intake of a supersonic aircraft is slowed by aerodynamic
diffusion created by the inlet and diffuser to low velocities
• Expansion of hot gases after fuel injection and combustion accelerates
exhaust air to a velocity higher than that at inlet and creates positive thrust
Fuel
injectors

3. KEY RESULTS: RAMJET
• Begin with non-dimensional thrust
equation, or specific thrust
• Ratio of exit to inlet velocity
expressed as ratio of Mach numbers
and static temperatures. Recall that
for a Ramjet Me=M0
• Ramjet specific thrust depends on
temperature ratio across burner, tb
– Compare with H&P EQ. (5.27)
• Energy balance across burner
• Expression for fuel flow rate for
certain temperature rise of incoming
mass flow and fuel energy, h
• Useful propulsion metrics
– Specific impulse, thrust specific
fuel consumption, and overall
efficiency
 
 
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h
m
TU
T
m
TSFC
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T
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M
M
T
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M
M
RT
RT
M
M
U
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U
M
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T
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overall
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sp
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t
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4. WHAT DID WE LEARN?
• Figure 5.9 from Hill and Peterson: Ramjet performance parameters vs. flight Mach number
• Specific thrust has peak value for set Tmax and Ta
• Specific thrust increases as maximum allowable combustor exit temperature increases
• Specific fuel consumption decreases with increasing flight Mach number

5. WHAT DID WE LEARN?
• Figure 5.10 from Hill and Peterson: Ramjet performance parameters vs. flight Mach number
• Specific thrust has peak value for set Tmax and Ta. Peak is around Mach 2.5
• Propulsive, thermal and overall efficiencies increase continually with increasing Flight Mach number

7. RAMJET POWERED MISSILES
Boeing/MARC CIM-10A BOMARC A Surface-to-Air Missile
Aerojet General LR59-AG-13 liquid rocket; Two Marquardt RJ43-MA-3 ramjets

8. SOME DETAILS ON BOMARC MISSILE
• Flight testing started in 1952
– First launch from Cape Canaveral in September of 1952
• Bomarc A became fully operational in 1959
– Numerous deployments from Florida to Maine defended U.S. eastern sea board
• Booster on Bomarc A was source of problems
– Fuel was too corrosive to store in missile, so fueling took place immediately
before launch (increasing time to launch)
– Fueling process was also quite hazardous, involving three steps (white fuming
nitric acid, analine-furfuryl alcohol, and kerosene)
• New model that utilizes a solid fuel booster
– Bomarc B became operational in 1961, and featured a safer solid fuel booster
and more powerful sustainers
• Boeing built 700 Bomarc missiles between 1957 and 1964, and Bomarc in active
service until 1972
• Length 46 ft. 9 in, Wingspan 18 ft. 2 in, Speed Mach 2.8, Range 250 miles,
Ceiling 65,000 ft, Cost: $ 1,154,000 per shot
• Propulsion:
– One Aerojet General LR59-AG-13 liquid rocket
– Two Marquardt RJ43-MA-3 ramjets

9. MISS BOMARC
http://home.att.net/~ferguspcj/mbomarc/bomarc01.htm

10. HyFly RAMJET CONCEPT
• Hypersonic Flight Demonstration Program
• Cruise Flight Mach Number ~ 6
• Range 600 nm (1111 km)
http://www.globalsecurity.org/military/systems/munitions/hyfly.htm

11. HyFly RAMJET CONCEPT
http://www.designation-systems.net/dusrm/app4/hyfly.html
• HyFly program was initiated in 2002 by DARPA (Defense Advanced Research Projects Agency) and
U.S. Navy's ONR (Office of Naval Research) to develop and test a demonstrator for a hypersonic Mach
6+ ramjet-powered cruise missile
• Prime contractor for HyFly missile is Boeing, Aerojet builds sustainer engine
• Air-launched from F-15E and accelerated to ramjet ignition speed by solid-propellant rocket booster
• Engine runs on conventional liquid hydrocarbon fuel (JP-10)
– Much easier to handle than cryogenic fuels (LH2) used on other hypersonic scramjet vehicles
• Sustainer engine of HyFly is a dual-combustion ramjet (DCR) (very complex)
– Two different air inlet systems
• Operate as a "conventional" ramjet with subsonic combustion
• Operate at hypersonic speeds as a scramjet
• First scramjet engine (hybrid or otherwise) to demonstrate operability with LH2 fuel

12. RAMJET POWERED MISSILES
Orbital Sciences GQM-163 Coyote: Ducted rocket/ramjet engine, Flight speed up to Mach 2.8 at seal-level
http://www.orbital.com/
Hercules MK 70 rocket booster

13. RUSSIA'S P-700 GRANIT LONG-RANGE ANTI-SHIP
MISSILE (SS-N-19 ‘SHIPWRECK’)
• Launched by two solid-fuel boosters
before sustained flight with ramjet
• Maximum speed believed ~ Mach 2.25
• Range is estimated at 550 to 625 km
• Weight: 7,000 kg, Length: 10 m,
Diameter: 0.85 m
• Altitude up to 65,000 ft

14. J58 SR-71 ENGINE: RAMJET/TURBOJET HYBRID
http://aerostories.free.fr/technique/J58/J58_01/page8.html

15. MAIN IDEA: TURBO-RAMJET

16. J58 TURBO-RAMJET

17. RAMJET VS. SCRAMJET
• Large temp rise associated with deceleration from high speed to M~0.3 for combustion
• Solution for increased flight speed: decelerate to ‘lower’ supersonic speeds in combustor
• Combustion very difficult (flame support) in a high speed flow
• Vehicle cooling requirements become very challenging

18. X-51

19. SUMMARY
• Ramjet develops no static thrust
• Relies on ‘ram’ compression of air
– Requires high speed flight
• Performance depends on increase in stagnation temperature across burner
(combustor)
• Efficiencies (thermal, propulsive, and overall) increase with increasing flight Mach
number
• Next step: We desire an engine that develops static thrust
– Put in a device to mechanically compress air (compressor)
– Put in a device to power compressor (turbine)
• Solution: Turbojet engine

20. INTERSTELLAR RAMJET: ‘HYDROGEN-BREATHING ENGINE’
• In this concept, interstellar hydrogen is scooped to provide propellant mass
– Hydrogen is ionized and then collected by an electromagnetic field
• Onset of ramjet operation is at a velocity of about 4% speed of light
• Typically, interstellar ramjets are very large systems
• A ramjet sized for a 45-year manned mission to Alpha Centauri would have a ram
intake 650 km in diameter and weigh 3000 metric tons including payload
http://www.daviddarling.info/encyclopedia/I/interstellar_ramjet.html