The Test Launches
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 a series of tests to iteratively develop the aerodynamics of the rocket plane 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
The actuators at the rear of the plane 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.
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.
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.