As you most likely are aware Indian Space Research Organizations (ISRO) who have effectively flight a scramjet engine.Only four nations in particular Russia,Australia,US and China how previously claimed to have flight tested this technology.
It was only in 1991 that the 1st flight test was performed by the Russians that is 22 years after man first arriving on moon. Likewise the longest flight test ever recorded by a scramjet was a little more than 200 seconds by US AIR FORCES as was Boeing X-51 Waverider. It shows to be a complex technology, to master to understand this technology better to start from basics.
As we all know to burn something we need air.That is the reason why Rockets traveling beyond Earth’s atmosphere carry its own supply of oxygen or oxidizers. But the present-day Rockets use oxidizers or oxygen even then it is traveling through the Earth’s atmosphere considering that
almost 50 percent of rockets weight is oxidizers wouldn’t it be great to use atmospheric oxygen during this time that is exactly what an average jet engine is designed to do.
There are 3 types of jet engines namely (a)turbofan or turbojet, (b)ramjet and (c)scramjet. All these engines work similarly but differ in the way how
air is compressed before being burnt in the engine. The turbofan is the familiar aircraft engine where a gas turbine based compressor is used to compress the air.On the other hand both scramjet and ramjet engines do not have a compressor but utilize the high speed forward motion to compress the air.
This chart compares the performance of different air breathing jet engine and shows the speed at which they can operate.That scramJets are the fastest among jet engines and that is the reason why there is a great deal of excitement about scramjet engine.
How does the scramjet work?
Scramjet stands for supersonic combustion ramjet ( s-c-ramjet). As I said earlier scramjet engines utilized the high-speed forward motion, to compress the air fuel and then injected in combustion chamber.Where it mixes with the hot compressed air and ignites the resulting jet of heated exhaust gas propels the vehicle forward.
Disadvantages of Scramjet engine
However since the scramjet engine cannot function until the vehicle has gained enough speed it needs a different engine such as a rocket engine to get it to the required speed.Thus a scramjet engine cannot function independently which is its main drawback.
Solution However there is an intelligent solution to this which is exactly what ISRO did the flight test a launch vehicle usually has multiple stages each having its own engine usually the stage is jettisoned after the fuel burns out this is done to reduce the weight of the launch vehicle so when the second stage begins to fire up the launch vehicle is already traveling at a high speed therefore using scramjet in second stage would be the best way to overcome its drawback just ISRO did.
So why ISRO working on this technology?
The satellite launching business is valued at billions of dollars and companies such as SpaceX are aggressively using new technologies to compete with the market leaders. ISRO already has one of the lowest price per launch and charges just 60 percent of what the market leader Arian space charges.By incorporating new technologies such as scramjet and reusable launch vehicles ISRO trying to be more aggressive to gain a bigger pie of this huge business.
what is ISRO has achieved?
- The flight test of scramjet lasted for 5 seconds reaching a speed of Mach 6
- Which is 6 times the speed of sound this test has validated all scramjet systems developed by ISRO such as mixing and compressing of air at high speeds igniting the air fuel mixture and sustaining the flame
- ISRO claims that scramjet would significantly reduce the cost and increase its payload capacity of its launch vehicles
- ISRO has achieved all these by spending just 5.3 million dollars compared to over 250 million dollars spent by NASA for its x-43a project
ISRO chairman had to say after the launch it’s a very significant development for the country and the efforts of long-duration R&D he has paved way they right now we have been able to demonstrate for five
seconds now we have to do it for a longer duration and also we also have to work of the way of using this effectively in our launch we control in conclusion even though this technology is years away from being actually used in a launch vehicle this is nevertheless a small but significant step by ISRO