The Test Launch
Pulsar's reusable rocket will be able to launch as a conventional first stage rocket and, after delivering its payload, will be able to re-enter the atmosphere, slowing itself down to a speed at which it can fold out a wing and propeller engine to fly back to base for refueling and preparation for the next flight.
What we will be proving
Back in 2015 The University of Queensland and other startup companies built and tested a prototype of the flyback rocket booster, to test its aerodynamic characteristics and to prove its ability to fly with the wing deployed and to land. So we know that once the craft is back in the lower atmosphere, it can be controlled and landed safely.
What hasn't been tested before is its ability to maintain control as it returns from near space, where there is virtually no atmosphere, and re-enters increasingly dense air at near hypersonic speeds. This is the critical test that we will be conducting next. Using a rocket provided by Black Sky Aerospace, we will carry out our first test of the actuators at the tail of the rocket as it free-falls back from space.
We use the term "payload" frequently here. What is that? You can think of it as the luggage; the stuff that the system has been built to deliver.
Origin of Payload:
The word originated as a term to refer to the part of the cargo that would generate revenue, in other words, the 'load' that would 'pay' for the trip. It can include cargo, experimental equipment, and even passengers.
Testing in low air density
These actuators will be the only means of aerodynamic control as it slows the craft down from around Mach 5 (about 5000km/h, this is just an approximation, since the actual speed of sound varies somewhat, depending on the temperature variation as the craft descends through the atmosphere) down to well under Mach 1.
While the finished version of this spacecraft will be able to land itself on a runway near the launch pad, we won't be doing that for this test. We will simply deploy a parachute for it to land nearby.
The Speed of Sound
Throughout this article and most of this website, we will approximate the speed of sound as 1000km/h. In practice, the speed of sound in the atmosphere varies with the square root of the temperature of the air. At ground level, it's more like 1200km/h, but in the colder upper atmosphere where the rocket reaches the higher mach numbers that we discuss, it drops closer to 1000km/h. Mach 1 refers to the speed of sound. Mach 2 is twice the speed of sound, and so on.
If you want to know how far away a lightning strike was, count the seconds until you hear the thunder from it. Then divide it by three for the distance in kilometres. It takes sound about three seconds to travel one kilometre.
Working with Black Sky Aerospace
Black Sky Aerospace are quickly developing a strong reputation for reliability with their launches. So even though we are in development stage, they can guarantee the delivery of our payload to space. They follow the same delivery standards as NASA, whereby they guarantee us mission success. Success for us requires sending a payload beyond the 100km threshold to space. If they don't reach that height on the first launch (and incidentally, they have a 100% mission success record), they will do it again.
Australia's first commercial rocket launch in 2018 - Black Sky Aerospace
We will be using Black Sky's Sighter 470 rocket for our test and to put your payload into space. The altitude it will reach is based on the size of the payload as shown in the graph below:
The Launch Profile of this test
Currently, Black Sky Aerospace is launching from southern Queensland, Australia, near the town of Goondiwindi. The Sighter 470 rocket containing our payload as well as our actuators, will launch and maintain a vertical trajectory as it accelerates to about Mach 6. By the time it reaches this velocity, it will have entered near space, above 99% of the atmosphere. At this point, the engine will stop and it will continue to coast upwards at high speed. The payload will be experiencing weightlessness as it will be effectively "free falling" upwards, into the vacuum of space. The generally agreed altitude where outer space begins is 100km. This is called the Karman Line. The rocket will pass this line and continue climbing.
Depending on atmospheric conditions on the day, and other variables, it will reach a height of between 130km and 150km. During the upward coasting phase, the rocket will separate from our payload, allowing us to carry out our return to atmosphere tests.
Apogee and free fall
After reaching apogee (our peak altitude), our payload section will begin free falling back to earth and rapidly gaining speed. The total period of near weightlessness will be around 4 minutes. It will accelerate to around Mach 5 before the atmosphere becomes dense enough to start slowing it down.
This is where the actuators will come into play, largely acting like tail feathers on an extremely fast moving arrow. We will be running tests to make sure that we can maintain directional control even in extremely thin atmosphere, as well as confirm the control inputs required to slow the spacecraft down effectively.
Parachute and landing
Eventually the atmosphere will become dense enough for the parachute to become effective, at which point it will be released, and slow the payload section down for it to float slowly back to the ground. We will have a recovery team that will be tracking the payload and they will be there when it lands.
The Karman Line: 100km
The Karman Line is the agreed border of space, at 100km altitude. Of course, since the atmosphere gets thinner very gradually, there are still a few atmospheric particles at this height, but it's viewed as negligible. From the Karman Line onwards, it is considered Outer Space.
You are making this happen
This will be a very valuable test. It will be a large step forward in our developing a reusable rocket system and sustainable access to space. Your contribution toward funding this test by purchasing payload items that have been on this journey up into space and back makes this possible.
So if you decide to join us in this way, we genuinely thank you. It also helps us fulfill the other mission of Pulsar Aerospace, which is to help as many people as possible to experience the transforming benefits of the Overview Effect.