GS Mains Model Question & Answer: Scramjet engine test is
a milestone for ISRO’s future space transportation system
Q. Scramjet engine test is a milestone for ISRO’s
future space transportation system. Comment. (12.5 Marks)
(General Studies Mains Paper III- Science and Technology : Space)
Model Answer :
The successful technology demonstration of air-breathing scramjet engines in
flight by ISRO is a modest yet important milestone in its endeavor to design and
develop advanced air-breathing engines including engines for ISRO’s future space
A scramjet engine is an improvement over the ramjet engine as it efficiently
operates at hypersonic speeds and allows supersonic combustion. Thus it is known
as Supersonic Combustion Ramjet, or Scramjet. India is the fourth country to
demonstrate the flight testing of a Scramjet Engine. A ramjet is a form of
air-breathing jet engine that uses the vehicle’s forward motion to compress
incoming air for combustion without a rotating compressor.
History of Scramjet :
In the 1950s and 1960s a variety of experimental scramjet engines were built
and ground tested in US and the UK. In 1964, two physicists - Dr. Frederick S.
Billig and Dr. Gordon L. Dugger - submitted a patent application for a
supersonic combustion ramjet. In 1981 tests were made in Australia under the
guidance of Professor Ray Stalker. First successful flight test of Scramjet was
performed by Russia in 1991.
Components of a Scramjet :
The scramjet is composed of three basic components:
- A converging inlet, where incoming air is compressed and decelerated
- A combustor, where gaseous fuel is burned with atmospheric oxygen to
produce heat and
- A diverging nozzle, where the heated air is accelerated to produce
Advantages of Scramjets:
- It does not have to carry its own oxygen, rather Scramjet picks oxygen
from the atmosphere
- Since, there are no rotating parts its a whole lot easier to manufacture
than a jet engine / turbine
- Has a higher specific impulse (change in momentum per unit of propellant
expelled) than a conventional engine.
- Since a scramjet carries no oxidizer tanks, it can be much lighter,
faster, and ultimately cheaper than conventional rocket technology.
- Its only exhaust is water, released from combining hydrogen, the fuel,
with oxygen, the oxidizer, and it needn't discard massive empty tanks as
conventional rockets do.
Disadvantages of Scramjets:
- Testing scramjet designs use extremely expensive hypersonic test
chambers or expensive launch vehicles, both of which lead to high
- A scramjet cannot produce efficient thrust unless boosted to high speed,
around Mach 5, although depending on the design it could act as a ramjet at