SCRAMJET ENGINE - SCIENCE AND TECHNOLOGY 
News: Hot
test of scramjet engine conducted successfully
What's in the news?
●       The
Indian Space Research Organization's (ISRO) quest to fabricate credible next
generation air-breathing scramjet engines, in order to launch satellites in a
predetermined orbit at a low cost, crossed a key milestone on December 9
evening.
Key takeaways:
●       The
engine's 11 second-long hot test was conducted successfully at ISRO's Propulsion Research Complex at
Mahendragiri in Tirunelveli district of Tamil Nadu.
Scramjet Engine:
●       The
scramjet, a more advanced version of the ramjet engine, can operate efficiently
at hypersonic speeds. 
●       It
allows supersonic combustion by breathing
oxygen from the atmosphere during flight.
●       It
then allows the oxygen to mix with hydrogen already stored in the vehicle to
trigger combustion, and produce the desired thrust to lift the satellite to its
designated orbit.
●       Scramjet
powered vehicles are envisioned to operate at speeds up to at least Mach 15.
Significance:
●       The
scramjet engine has a capacity to reduce
nearly 70% of the propellant needed for the launch.
●       As
the hydrogen is used as a propellant and combustion is carried out at
supersonic velocity with the help of oxygen from the atmosphere. 
●       As
a result of that, steam (H2O) is being exhaust gas which is eco-friendly in
nature.
●       Less
weight and simple design. 
Go back to basics:
Ramjet Engine:
●       A
ramjet operates by combustion of fuel in a stream
of air compressed by the forward speed of the aircraft itself, as opposed
to a normal jet engine, in which the compressor section (the fan blades)
compresses the air. 
●       The
airflow through a ramjet engine is subsonic, or less than the speed of sound. 
●       Ramjet-propelled
vehicles operate from about Mach 3 to
Mach 6.