HYSHOT – Taking Australian scramjets to the air

Did you know that a small group of scientists at UQ beat NASA and others in 2002 to be the first to successfully test a scramjet in flight?

In the late 1990’s the world was still waiting for the first flight test of a scramjet.  A group of scientists and students at UQ led by Professor Allan Paul changed all that.

As we talked about in last weeks blog , the T4 shock tunnel at UQ had been testing scramjets on the ground since 1989.  In the decade of the 1990’s many thousands of tests were conducted in T4, and a broad understanding of how scramjets worked was learned. 

In fact the scramjet shown in Figure 1 was the first ever to produce positive net thrust in the laboratory.  In more basic terms this meant that this scramjet would accelerate, and might one day be useful for replacing rockets in a space launch system.

Scramjet on a stick

Scramjet on a stick

Despite these impressive results, there was still some doubt expressed in the scientific community about the shortness of T4’s test time. 

Did a test lasting only three thousandth’s of a second actually represent reality?   Would a scramjet work the same way if it flew for 3 seconds, or even 30 minutes?

The researchers decided real-world testing was required to confirm their work in the shock tunnels, and UQ’s world famous HyShot Program was born.

Hyshot involved attaching a scramjet engine to the top of a rocket.  This vehicle needed to accelerate to around Mach 8 in atmosphere, but stay on a safe trajectory. 

Professor Allan Paull and his team found a rocket supplier from the USA and devised the flight plan, shown in Figure 2. The rocket would launch vertically and punch through the atmosphere, gaining speed until it reached 56km in altitude.

At this height the atmosphere is too thin for the scramjet to work, so it would coast all the way to a peak altitude of 314 km, then return to earth due to gravity.  Remember space starts at ~100 km and a scramjet can only work in the atmosphere below around 40 km altitude.

The Hyshot scramjet would turn itself on at around 35 km altitude as it plummeted back to the ground at over Mach 7.

Hyshot mission profile

Hyshot mission profile

The scramjet flown on the HyShot flights is shown in Fig. 3.  So many things can go wrong in flight, and the budget was very tight, so it was decided to use a simple scramjet shape.  It was a wedge intake with flat side walls. 

A nosecone covered the scramjet on the way up to protect it from the immense heat experienced when flying at hypersonic speeds.  Once the rocket and scramjet reached about 75 km, the nosecone was blown-off and the rocket-scramjet returned nose first. 

It was necessary for the scramjet to remain attached to the rocket motor, otherwise it would need its own wings and control surfaces in order to fly straight.

Hyshot scramjet prepared for launch

Hyshot scramjet prepared for launch

As well as reaching over 300 km altitude above the earth (higher than the international space station), HyShot flew 400 km down range.  That’s a long distance.  Where do you have enough space to do that? 

Well, Australia is a big place and the Australian Government manages a flight test range called Woomera. which is in the outback of South Australia. 

It is one of the largest land based ranges in the world and it was perfect for HyShot.  Thanks to support from the Australian government, Hyshot was allowed to fly from Woomera.   Figure 4 shows Hyshot on its launch rail before flight.

HyShot 1 flew on 30 October, 2001.  As often happens with testing, things did not go to plan, the rocket flew off course and the scramjet test failed.  But scientists are persistent, and thanks to help from many organisations in Australia and overseas, a second HyShot flight was able to take place less than a year later.

Hyshot at Woomera, SA

Hyshot at Woomera, SA

On July 30, 2002, HyShot 2 took to the sky and made history.  Figure 5 has a link to video footage of the exciting launch.  The rocket blasted the scramjet into space, reaching over 300km in altitude before falling back to earth at hypersonic speeds. 

At 35 km altitude the fuel system opened, and for three seconds the world’s first scramjet engine burned in flight.  This was a momentous occasion not only for the HyShot team, but also for Australia. 

As a small group of scientists and students from a University on the great southern continent beat the rest of the world to an important milestone in aerospace history.

As well representing an important milestone in Australian history, Hyshot also proved that all the hypersonic tests that are done in the laboratory at UQ are as close as we can get to flight. 

So when Hypersonix gets the chance to fly the SPARTAN scramjet, we can have confidence that it too will operate in the same way it does in the laboratory.