September Astronautics

[septemberWaves]

Part 2: ORBs

Ysgard I Testing

The Torch engine has a good enough track record so far for us to consider it as a propulsion method for an orbital launch vehicle. But there is no way a single Torch will send anything to orbit. For the purpose of sending useful payloads into space and keeping them there for a reasonable amount of time, Ysgard I was designed. This launch vehicle uses 20 Torch engines: four on the central rocket stack, and four on each of its radially-attached boosters (of which there are four). The core engines are tuned down to 70% thrust, while the booster engines are at full thrust. All ignite on the ground, and the core engines will burn throughout the launch until the payload reaches orbit.

The immediate question is: what will be the first artificial object to orbit Kerbin? Well, despite the success record of the Torch engines, using 20 liquid-fueled engines on the same vehicle poses a high chance of failure; the first payload of Ysgard 1 is a simple ORB-class satellite with essentially no purpose other than travelling around Kerbin at four kilometers per second and being drastically cheaper than anything else we might want up there. The first ORB-class satellite to successfully reach orbit will be retroactively named Dione 1.

Spoiler

ORB-1 sits on the launch pad, awaiting liftoff.

Ignition. All engines ignite successfully.

Liftoff of ORB-1.

Flight appeared nominal, but upon starting the pitch program, several engines failed. All core engines, as well as three on Booster 2 and two on Booster 4, failed simultaneously, and the vehicle spun out of control before being torn apart by aerodynamic forces.

After several weeks, ORB-2 is ready for launch.

Liftoff of ORB-2.

Despite the engines working this time, the rocket lost control. It seems that the 1° gimbal of the Torch engines is insufficient at this stage of flight.

 

Dione 1

As is probably obvious by the name of this launch, the third attempt at placing an ORB-class satellite into Kerbin orbit was a success. This version of the Ysgard 1 launch vehicle, as well as all subsequent versions, has been augmented with an aerodynamic fin on each booster, to assist with attitude control in the lower atmosphere and avoid a similar failure to that which occurred on the ORB-2 mission.

Spoiler

This is the point by which both previous launches had failed. This time, the launch continues without issue.

Reaching the point of maximum aerodynamic pressure.

Booster cutoff and separation.

The launch continues.

Shortly after booster separation, one of the core stage engines failed and lost all thrust.

The flight trajectory was able to be corrected, but the opposite engine had to be remotely shut down to balance the direction of thrust.

This situation has led to the available thrust being halved, but the launch vehicle was designed to be able to cope with this scenario, and will still reach orbit if nothing else goes wrong.

Fairing separation.

As the vehicle approaches apoapsis, it has to turn so that its trajector is radial. The engines cannot be re-ignited after they shut down, so they must continue burning until the vehicle is in a stable orbit.

Dione 1 successfully reached orbit of Kerbin.

The probe separates from the launch vehicle, and deploys its antennae.

Dione 1 is not a complex device by any means, but this mission success will serve to increase confidence in our space program, granting us more lucrative contracts and more funding to expand our capabilities further.

 

Spark engine static fire test 1

Ysgard I works as a launch vehicle, but we are already looking to upgrade it. We will need a new engine for the upgrade. The Spark engine is optimized for upper stages, can be throttled down to 50%, and can be reignited several times. This testing rig allows us to test 24 Spark engines at once, with a burn time of nearly five minutes.

Not long into the test, all but four of the engines had lost thrust, and the remaining ones could not be shut down without cutting off the fuel transfer. Clearly some improvements are needed before we can make use of these engines.

 

Dione 2

Dione 2 will be our second orbital probe. It uses the same spherical computer brain as Dione 1, but also includes various other equipment. Dione 2 has several objectives: collect scientific data from space; test out the new RCS thrusters as a form of attitude control in a vacuum; and return safely from Kerbin orbit. That last one is quite a challenge, considering the fact that it will somehow have to survive the process of slamming into the atmosphere at over 4000m/s. Dione 2 is equipped with an ablative shield which should allow it to return to the lower atmosphere intact, and with a low enough velocity to allow its parachute to deploy.

Spoiler

The launch was flawless. Not a single engine failed, and the probe reached orbit safely.

The shape of the probe is important. Most of the mass is concentrated towards the end with the heat shield, which should naturally orient it in that direction once it re-enters. While in space, however, its only way to control which direction it is facing is by using the tiny thrusters that are dotted around the sphere. These are simplistic liquid rocket engines that use a single propellant rather than a bipropellant mixture, so they should be less likely to fail. They can also fire for incredibly short amounts of time, and can independently limit their thrust output, so (if they function) they will be a useful method for correctly orienting spacecraft.

After collecting some data and sufficiently testing out the RCS thrusters, the probe uses four of these thrusters to de-orbit itself. It burns radially for this purpose because the apoapsis is too high for the limited power of the RCS thrusters to make a retrograde burn while the probe still has a connection to the space center.

The probe re-entered on a shallow trajectory, and travelled halfway around the planet before it began to experience any significant heating effects. As expected, the position of the center of mass forced the heat shield to the front of the craft, keeping the fragile components of the probe safely out of the airstream.

Landing was successful (although an antenna broke) and the probe was recovered safely. This is an incredibly important milestone, as it proves that it is possible to return from orbit without being destroyed.

 

Spark engine static fire test 2

After the launch of Dione 2, we conducted another static fire test of 24 Spark engines.

This time, the test was perfect. Every engine fired consistently for the full 4 minutes and 49 seconds, the gimbal systems worked on every engine, and the thrust limiting was also tested to satisfaction. The Spark engines are likely to see use in the near future.

[septemberWaves]

Part 3: First kerbal in space

Crewed Sounding Rockets

In order to prepare for sending kerbals to space, it is first important to test some key systems that spacecraft will require.

The Type E sounding rocket is the first crewed rocket to be launched. Its pilot, Giry Kerman, will become the first kerbal to break the sound barrier. The rocket is propelled by a single Reliant engine, which lacks the ability to gimbal, so control is provided by actuated fins.

Spoiler

 

The cockpit is not exactly spacious, but kerbonauts will have to get used to small spaces, as it is currently far beyond our capabilities to send large habitats to orbit.

Liftoff of Type E-1.

The rocket pitches down shortly after takeoff.

Not long into the flight, Giry Kerman is travelling near-horizontally, and - more importantly - faster than the speed of sound.

The engine is shut down shortly after this milestone is reached.

The entire rocket is designed to be recovered, but in the event of a failure the cockpit would separate from the propulsion module and land independently.

The landing was successful, although the landing legs all broke off.

 

 

Building on the success of the Type E sounding rocket, the Type F was designed as a direct upgrade.

This vehicle is designed to send a kerbal to the edge of space and back. Unlike its predecessor, the Type F will not be recovered intact - only the command module will survive. The crew of this launch is Megner Kerman.

Spoiler

Liftoff of Type F-1.

This rocket uses a steeper trajectory than the previous launch. It launches north so that the command module will land on land, making recovery easier.

The engine cuts off as the target apoapsis is reached.

Megner Kerman has become the first kerbal in space. Sending a kerbal to orbit will require more advancement, but this is a significant milestone.

The landing was flawless, and Megner Kerman was recovered safely.

 

Methone 1

Methone 1 is a satellite designed to conduct long-term surveys of the magnetic field environment in space around Kerbin. Its mission requires a highly-elliptical near-polar orbit, which makes it the first passenger of the new Ysgard II rocket. Aside from a new paint job, Ysgard II uses a slightly modified Ysgard I rocket as its lower stage (the core has a shorter tank and therefore less fuel and a shorter burn time), and has an upper stage propelled by six Spark engines.

Spoiler

Liftoff of Methone 1.

Shortly after the beginning of the ascent, the rocket lost control. It is not fully clear why this happened.

After time spent deliberating over the problem, it was found to be an issue with the flight trajectory. The ascent profile was modified, and a new rocket was constructed.

The failed first attempt at launching Methone 1 was an expensive loss. The satellite carries some costly scientific equipment, a more advanced processor than our usual ORB probe cores, and some photovoltaic panels for power generation. It is important that the launch of the replacement satellite will be a success.

Liftoff of Methone 1A.

This time, the rocket performs well in the lower atmosphere.

Booster cutoff and separation.

Following cutoff and separation of the first stage, the upper stage's six Spark engines propel the payload until it reaches orbit.

Fairing separation. The reason such a large fairing is used for this small payload is that the rocket is also designed to launch larger payloads, and using the same fairing size reduces manufacturing costs. There is also a larger fairing available for the rocket, but that is designed for crewed launches only.

The vehicle points radially inwards as it approaches orbit. The Spark engines can be ignited multiple times, but not without a way to stabilize the fuel (the first ignition took place while the rocket's first stage was still burning).

The satellite reaches orbit successfully, and is deployed.

Its orbit is sufficiently eccentric to pass through Kerbin's magnetic fields - at least, where they are predicted to be. The instrumentation will survey the magnetic field environment so that the R&D department can compare to their models of exactly where not to put a space station if you do not want your crew to become irradiated.

 

Avernus LES Test

Avernus is the name of the first vehicle designed to send a kerbal to Kerbin orbit. Before it can do so, however, it must be tested, starting with the launch escape system.

This pad test is intended to ensure that the launch escape tower can safely pull the crew capsule away from the rest of the vehicle. If an issue is found here, it will have to be solved before any in-flight tests are done.

The solid-fueled launch escape tower ignites successfully, and the fairing separates with plenty of force to avoid any collision.

The launch escape tower failed to separate properly from the capsule, but the parachutes were able to deploy. The capsule is not actually intended to be recovered intact; it contains an ejector seat for the pilot, who will reach the surface with a personal parachute. The ejector seat also functioned as predicted in this test, though because this test was done from near the ground, rather than the top of a launch vehicle, there would not have been sufficient time for a kerbal to activate their parachute, if there had been a pilot present for this test.