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| The British Amateur Space / Rocket Programme |
The ASPIRE II rocket is the main focus of the AspireSpace Rocket Programme.
Originally planned to be launched in 1997, the schedule has had to be stretched out due to a shortage of sponsorship. Although unfortunate, it does also at least allow more development time of the subsystems. Because of this, a vigorous hybrid development programme is underway, with the team building up as much experience as possible with the smaller AspireSpace hybrid motors. The delay also allows more avionics sub-systems tests to be scheduled for flight testing on the ASRV rockets.
The ASPIRE II rocket will use a new generation of airframe, motor and avionics system, in light of the ASPIRE I, ADV and ASRV experience. This rocket will use a high pressure hybrid motor. This vehicle will be used to flight test the autopilot/guidance system, and also to evaluate materials for possible use on the British SKYLON spaceplane.
Subsequent launches of ASPIRE II, depending on financial resources available, will aim to fly a range of school and university payloads.
Payloads to be carried are varied, and include Remote Sensing and Astronomical Payloads, as well as the waverider hypersonic test vehicle. More details can be found on the Payloads Page.
AspireSpace Small Hybrid Motor Static Test Firing (Large Photo - 48K)
Test Duration = 60 seconds
ASPIRE II Design
The ASPIRE II Rocket makes use of a hybrid motor. Hybrid motors combine good features of both Solid and Liquid Fuelled rockets. They are controllable, semi storable, cheap and simple. They are based on the principle of a solid propellant and a liquid oxidiser.
The hybrid motor under development for ASPIRE II was originally designated the H100 motor (due to the fact that it uses 100 kg of propellant), but due to slight growth, is now known as the H1xx motor.
The Aspire II avionics consists of 4 units. The first unit, the Telemetry and Control System, forms the heart of Aspire II's avionics and is connected to all the other units and the payloads via the Aspire Intermodule Bus (AIB), a fast digital serial link. The units are as follows:
1. Telemetry and Control System (TCS)
The TCS performs two functions:
i. Telemetry and monitoring.
The TCS collects data from the payloads carried by Aspire II. It also gathers information about the operational status of all the other onboard systems, such as the engine and its propellant supply system. The TCS also collects data from its own Standard Sensor Array (SSA). This is a bank of sensors which are flown on every mission to collect important data about the rockets' flight such as airspeed, altitude, attitude and acceleration.
The TCS formats all this data and sends it to the ground via a UHF radio transmitter. The data is sent in digital form using Frequency Shift Keying (FSK) modulation. At the ground station, the data is displayed to the ground crew and also stored on disk for post-flight analysis.
ii. Telecommand, control and sequencing
The other function of the TCS is to act as a central controller and sequencer for the other systems and payloads on the rocket. Despite this, most of Aspire II's systems are designed to run autonomously if necessary. The TCS allows the ground crew to control various systems on the rocket remotely during pre-flight procedures and, if necessary, during flight. This is accomplished using a VHF radio uplink from the ground station to a receiver in the TCS.
The TCS is based around a 68332 microcontroller chip.
2. Guidance System (GS)
The GS stabilises the rocket and ensures its progression along the correct trajectory. It is based around a 68332 microcontroller chip. The GS contains an inertial reference (gyroscope) to provide data about the rocket's attitude. This is processed using fuzzy logic algorithms to produce correction signals which are fed to the thrust vectoring actuators. Thrust vector control (TVC) will probably be accomplished by gimballing the motor, though other TVC techniques are being investigated.
The GS is referred to as a "Genetically Adaptive Active Control Guidance System".
The gyroscopes and accellerometers which make up the inertial reference, have been scratch built by AspireSpace in order to reduce costs. This goal has been achieved without sacrificing accuracy of the measurements. Comprehensive bench testing and flight testing on small rockets, has validated this approach.
3. Recovery System Controller (RSC)
The RCS contains circuitry for initiating and sequencing the operation of the vehicle's recovery parachute system.
4. Engine Management System (EMS)
The EMS contains circuitry for sequencing the start-up and running of the hybrid rocket motor and its propellant supply system. The EMS also contains a controller to regulate the propellant feed pressure and provide a programmed sequence of throttle (thrust) settings during flight.
General details:
The payloads are connected to the TCS via the AIB. To give the payload providers a simple, user-friendly interface, there is no direct access to the AIB. Instead, they are connected to the AIB through a Payload Interface Unit (PIU). The PIU has a number of analogue and digital data lines for the payload provider to connect to. Every payload has its own PIU.
The steerable parachute is ejected post apogee at high altitude where the atmosphere is minimal. It is then allowed to settle down as the vehicle speeds up and the Q increases. NO shock loads. Just a steadily increasing load up to max parachute deployed reentry Q.
Stratospheric shear layers have to be guarded against. The method AspireSpace use is a step function to calcuate the conditions, enabling a good safety margin. Studies and calculations are currently being carried out into the bending stresses about the Centre of Gravity.
The steerable parachute recovery system is progressing well, with flight tests having been carried out on the main parachute, at altitudes of up to 200 metres. The onboard CCD video camera for virtual piloting of the recovery system, performed flawlessly, transmitting live images to the ground station, which were then archived on video for detailed examination. Flight tests have been carried out in 1994, 1995 and 1996. More tests are planned for the next few years.
ASPIRE II Steerable parachute
ASPIRE II Recovery system undergoing flight test
T0 - T+5 seconds: Thrust at 8000 Newtons (Initial acceleration of +5G).
T+5 - T+65 seconds: Thrust at 4000 Newtons (This gives ASPIRE II a sustained burn which provides heavy acceleration at between 40 to 50 Km which accelerates the rocket to Mach 7.5).
ASPIRE II Thrust Profile
As ASPIRE II has followed on from the ASPIRE I rocket, so too will ASPIRE II lead on to greater things, with the development of the waverider, and the much more ambitious ASPIRE III rocket.
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aspire-info@gbnet.net