ARCASPACE
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- For other uses of "ARCA", see ARCA.
Asociaţia Română pentru Cosmonautică şi Aeronautică (ARCA) or Romanian Cosmonautics and Aeronautics Association is a non-governmental organization that promotes aerospace projects as well as other space-related activities. It is based in Râmnicu Vâlcea, Romania.
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[edit] Beginnings
In Sibiu, Romania, in front of the Hermann Oberth memorial house, a group of students decided to intensify the low-level space activities in Romania. ARCA's members started to develop an ambitious high-performance rocket engine in 1998. ARCA was registered in 1999. Since then, ARCA became a united team and, despite a small budget in the first years, it succeeded in leading the field in rocket technology in Romania.
The first aerospace project started in 1998 was a high performance rocket engine designed to deliver 85,000 kgf. The engine used open cycle and the 4 burning chambers were fed with liquid oxygen and kerosene at the combustion pressure of 70 bars.
The purpose of this project was to develop the abilities and skills needed for future activities by using local technology and materials. Another achievement was the creation of a united and specialized team of rocket engineers.
[edit] Early Vehicles
[edit] Demonstrator
This technological demonstrator is at 1:2 scale of that of the X PRIZE vehicle, named Orizont and it is the first rocket designed by ARCA Team. It is an unguided but self-stabilized rocket. On this vehicle and on the sub-assembly systems many constructive solutions were tested, especially composite materials fuel tanks. Almost the entire structure is made of composite materials, but also from aluminium aloys. This rocket was created to simulate an almost complete (unmanned) X Prize mission. Demonstrator 1 was also used in public exhibitions in order to attract more funds for ARCA projects.
The old configuration used a liquid fuel rocket engine, designed to thrust 2,000 kgf during 60 sec. The fuel was: hydrogen peroxide 85% + T1. In the new configuration will use a hybrid engine with hydrogen peroxide 85% as an oxidizer, in combination with polyethylene as fuel.
[edit] Demonstrator 2
The technological demonstrator "2" is at 1:2.5 scale of that of the X PRIZE vehicle, named Orizont. ARCA started the work to this rocket in May 2003. The entire structure is made of composite materials. For this vehicle was created a whole launch complex, including the launch pad, the fuel transfer facility, etc. For this vehicle two propulsion configurations were proposed: monopropellant and hybrid.
Demonstrator 2 was the starting point for the development of the successful Demonstrator 2B rocket. The first public display of this vehicle took place in Drăgăşani, on September 27, 2003.
[edit] Demonstrator 2B
Demonstrator 2B is a modified version of Demonstrator 2, equipped with the world's first reusable rocket engine made of composite materials. The main objective of this rocket was to test in flight the engine and the vehicle-launch pad interaction in order to gather more data for the Orizont vehicle construction. For the Demonstrator 2B launch was used the Demonstrator 2 launch pad which was modified (the length was increased to 18.2 m) and also the command panel and fuel transfer facility previously developed at ARCA.
This rocket was the end of subscale systems tests at ARCA and the beginning of the Orizont vehicle's final phase of construction.
The Demonstrator 2B rocket was successfully launched on September 9, 2004. The measurements indicated that the launch parameters were: 1000 m altitude, 630 km/h, 2100 m range.
[edit] Stabilo
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| Length: | 6 m |
|---|---|
| Maximum weight: | 1000 kg |
| Crew: | 1 |
| Fuel: | H2O2 |
| Traction: | 30.000 N |
| Acceleration (boost phase) : | 4G |
| Acceleration (reentry): | 4.6G |
| Max speed: | 4.500 km/h |
| Max altitude: | 100 km |
STABILO is a the latest suborbital manned system created by the European Team ARCA. ARCA hopes that its new spaceship, through its unique design and safety capabilities will capture the attention and will stimulate the imagination of the public.
ARCA’s philosophy is that a manned suborbital ship for commercial applications must be designed taking into account the passengers and crew safety. For that purpose, the ship must have:
- a high reliability
- an excellent abort scenario and escape capabilities
- the stress for the pilot during flight reduced to minimum
In respect of these statements, ARCA team propose a new suborbital ship concept. The engine, placed at the top of the ship, offers an unconventional aspect for this spaceship. The tractor engine offers the possibility to place the crew cabin at the rear part of the ship, which offers extended abort capabilities. STABILO will be launched in a vertical position. In this situation the pilot activities are highly reduced.
The tractor engine, generates reaction gases, close to the ship structure for a long period of time, without affecting the ship integrity. This is possible due to the use of hydrogen peroxide as monopropellant which offers a low temperature for the reaction products. The purely space applications design of this ship makes it inappropriate for powered flights at low altitudes, in dense atmosphere. Because of that the system is transported to an altitude of 22.000 m with a Solar Montgolfier.
The tractor engine solution isn't new. It was previously used as escape systems onboard of Mercury, Apollo and Soyuz. The main difference is that an escape system has low burning time. STABILO's engine is running for long time, around one minute.
[edit] The Flight Sequence
[edit] The Launch
STABILO was designed to be launched from an altitude of 22.000m. It will be transported, during a 1h,35min. flight with a (350.000mc) Solar Montgolfier balloon. The launch will be made vertically, through the very thin balloon envelope. At the bottom of the balloon it is placed a composite materials ring of 2 m diameter through which the STABILO will enter into the balloon envelope.
[edit] Vertical powered flight
Immediately after the engine start, the vehicle will begin to accelerate on a vertical trajectory. The max. speed will be 1.250 m/s and the max. G load will be kept bellow 6.8 G.
[edit] Inertial vertical flight
After engine shut-down, the vehicle will continue the inertial to climb. Immediately after engine shut-down the crew cabin will be separated from the rocket booster. The RCS system will command the cabin attitude. The maximum altitude is above 100 km.
[edit] The reentry
After apogee the cabin and booster rocket will start the descent which for almost the half of the distance will be made in winglessness. At low dynamic pressure, the RCS will keep the cabin with the base down. The aerodynamic stability system placed at the top of the capsule will keep the vehicle into vertical position during the atmospheric phase of the reentry, without pilot intervention. The maximum deceleration during reentry will be -4.6 G.
[edit] The recovery
The rocket booster main parachute will be extracted from the nose-cone compartment at an altitude of 4.000 m and a speed of 400 km/h. The cabin main parachute will be extracted at 4.000 m and a speed of about 350 km/h. The landing speed will be kept bellow 7m/s.
[edit] The Monopropellant Rocket Engine
The main preoccupation for a spaceship designer is to ensure a high reliability. Since the appearance of rockets, until today, the main element that leads to a rocket vehicle failure is the engine. ARCA considers that the main issue that a designer has to deal with in order to create a reliable ship is the creation of a reliable rocket engine.
There are some alternatives, from the fuel point of view, regarding the type of a potential rocket engine that can equip such a vehicle: bipropellant liquid fuel, monopropellant liquid fuel, solid fuel and hybrid fuel.
Through 2000-2004, ARCA experimented a series of rocket engines with various types of fuels. After those tests in 2003 the team decided to go forward with a hydrogen peroxide monopropellant engine. This type of engine was tested intensively through 2003-2004. Demonstrator 2B rocket which was launched from Cape Midia Air Force Test Site on September 9, 2004 used this type of technology.
A monopropellant system used as a main engine for space propulsion is an unusual proposition mainly because of it’s low specific impulse. A vehicle launched from the ground, using this type of propulsion, in a suborbital mission, with a payload equivalent of about three passengers will be necessary to carry about 7 t of fuel, an unacceptable value. Furthermore, the final acceleration will be around 12G.
It is clear that a ship equipped with a hydrogen peroxide (85%) monopropellant rocket engine, able to complete the above mentioned mission is not suitable for a ground launch. However a 24% higher impulse can be obtained in the case of an air launch from an altitude of around 22.000m, with an almost fully adapted nozzle.
STABILO is the first spaceship that uses a monopropellant tractor engine this solution was choose because it offers a high security of the flight. Despite of the presence of the four nozzles placed at an angle of 20°, that could indicate four engines, STABILO has only one engine. The reaction gases from the reaction chamber are distributed through the four nozzles. The 20° angle lead to a 6% thrust loss. Despite this, ARCA engineers considered that the advantages of a high security of the ship resulting from a tractor engine are more important and the thrust loss could be compensated through a higher fuel quantity and a longer engine run.
The reaction is 100% ecological since hydrogen peroxide decomposes in oxygen and hot water vapors. Function of the mission nature, and fuel concentration (65-85%), the engine will be reusable or expandable. While the expandable engines raise no special problems, the reusable engines built from composite materials is a real challenge. Such engines were used before but with ablative cooling (inner layers vaporize in order to keep outer layers at a reasonable temperature). However, this process can be used on "hot" engines at high temperatures. At lower temperatures, the inner layers don't vaporize efficiently anymore. ARCA's engine accumulates the heat inside the inner and intermediate layers so that the outer layers don't change their mechanical characteristics even after a complete engine run. The heat is not released outside. This system is not very economical but is certainly very safe and reliable.
[edit] The crew cabin
The most important aspect of the whole project is safety. Therefore, safety and backup systems for the pilot were designed for every stage of the flight. With the cabin placed at the bottom of the ship, the abort sequence has a simple procedure: the crew cabin could be gravitationally separated from the rocket booster and it is recovered with its parachute. The cabin offers protection for almost the entire flight sequence, even in unlikely events like complete equipment failure, structural damage, etc.
The cabin is pressurized at 0.8 atm and contains navigation, flight control and life support systems. It is designed for one pilot that sits on a chair, specially designed for flight accelerations. The access inside the cabin is assured by a lateral auto-presurized hatch which can be opened both from inside and outside of the cabin. As an added safety, the pilot will use a pressurized suit, offered by another former X Prize competitor, which has a lot of experience with pressurized suits: DeLeon Company. DeLeon and ARCA are partners since 2005 and they are collaboration on a various aspects regarding the manned space flight.
The pilot has a panoramic view through three portholes. The position of the portholes was choose in order to offer to the pilot a complete view without being necessary to raise from its chair. The top engine with its four nozzles could offer a beautiful image to the pilot, since the exhaust, made of oxygen and water vapors will freeze immediately after ejection, in contact with the outside environment (-60 degrees C). The jet will form small ice particles on which the Sun will reflect. After engine stop and capsule release, the pilot could maneuvering the cabin with the RCS to have a view of the Earth with the four engine traces of ice beneath the ship.
[edit] The carrier balloon
The carrier balloon used to raise the ship at the launch altitude is a zero pressure Solar Montgolfier type, made of 15µm high density polyethylene. The balloon uses the Sun radiation to heat the inside air. This will lead to a temperature gradient between the interior and the exterior of the balloon. This gradient has a maximum value of around 30 degrees C, which makes the air from the inside to have a lower density comparing with the outside air. The balloon used for the Mission5-8 flights has a capacity of 350.000mc. It will be the biggest balloon of this type, ever build.
[edit] Stabilo flight program
| Flight | Category | Altitude | Ship configuration | Engine start |
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| Mission1 | Unmanned | 22.000 | Carrier balloon + Complete ship | No |
| Mission2 | Unmanned | 22.000 | Carrier balloon + Crew cabin | No |
| Mission3 | Manned | 22.000 | Carrier balloon + Crew cabin | No |
| Mission4 | Unmanned | 100.000 | Carrier balloon + Carrier rocket | Yes |
| Mission5 | Unmanned | 100.000 | Carrier balloon + Complete ship | Yes |
| Mission6 | Manned | 30.000 | Carrier balloon + Complete ship | Yes |
| Mission7 | Manned | 60.000 | Carrier balloon + Complete ship | Yes |
| Mission8 | Manned | 100.000 | Carrier balloon + Complete ship | Yes |
[edit] Orizont
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| Length: | 10 m |
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| Maximum wingspan: | 10 m |
| Jet engine length: | 1,5 m |
| Maximum weight: | 2000 kg |
| Crew: | 0-1-2 |
| Specific impulse: | 110s |
| Fuel: | H2O2-70% |
| Fuel for jet engine: | T1+ oxygen from atm |
| Traction: | 50.000 N |
| Acceleration: | 6G |
| Max speed: | 3.500 km/h |
| Max altitude: | 100 km |
The construction of ORIZONT began in mid-2004. At that time, ARCA was more concerned with the launch of Demonstrator 2B from Cape Midia and most of the members declined involvement in the ambitious ORIZONT project. However, a small group started the design and the construction of the new vehicle. The first element was the mold for the pressurised compartment of the spacecraft. The mold and the whole structure of the cabin were finished in February 2005.
The work itself was done in a very small workshop and it was obvious that the team needed a much larger space for the equipments and hardware.
At the beginning of June one of the major sponsors of ARCA offered an assembly facility of 1500m2. Here, they began assembling the ORIZONT vehicle.
[edit] Launch
The air-launch solutions are flexible due to the variable geometry of the wings and the solutions that were selected for the propulsion system. The launch can be executed, depending of the carrier availability, from helicopter or airplane. In every situation the launch will be made with the wings at near 0 degrees sweep angle because it is necessary that the wing to generate the highest possible lift. In the case of helicopter launch, the ORIZONT vehicle will be lift to an altitude of around 2,000-2,500 m. At this altitude, the vehicle will be released and it will gravitationally accelerate to the requested speed of about 210 km/h, necessary for the stable flight. In the case of the air launch, the ORIZONT vehicle will be transported to altitudes around 11,000 m, attached to the carrier at the top or at the bottom. Due to safety reasons, it is better to attach the vehicle at the bottom of the carrier. The launch from the helicopter is easier to implement from the logistical and technical point of view, but increases the stress of the cosmonaut because of the necessity to fly the ship in the atmosphere for a longer period of time.
[edit] Autonomous atmospheric flight
After the carrier release, the ORIZONT vehicle will start the air-breathing engine and will start to climb with the wings completely open to an altitude of around 17,000 m with a speed range of about 400-700 km/h. The maximum acceleration for this stage of the flight will be no higher than +4.6/-1.6 G
[edit] Rocket engine
Immediately after the vehicle reaches the desired altitude, the air-breathing engine will be detached. This action is shortly followed by the modification of the wing sweep angle to a minimum value. The lift and drag will decrease significantly.
[edit] Rocket engine vertical flight
The rocket engine will be started when ORIZONT will have 45 degrees angle of attitude which can be obtained from the stabilizers. Immediately after the start the vehicle will begin to accelerate rapidly, the aerodynamic surfaces putting the vehicle to a near vertical trajectory. This trajectory will be kept for the entire time of the rocket engine run.
[edit] Inertial vertical flight and the reentry preparations
After the rocket engine shut-down the ship will continue to climb inertly in a vertical position; in this time frame, the pilot will start the reconfiguration of the whole ship for re-entry mode: the wing sweep angle will be changed to a negative position and the stabilizers will change their position by 180˚. The low atmospheric density from those altitudes will not allow the pilot to control the altitude of the ship from the aerodynamic surfaces and the ship will be controlled with the reaction control system (RCS).
[edit] Flight
At the maximum altitude of 100 km, the ship will have the lowest speed from the entire flight sequence. The pilot will continue to control the ship with the RCS.
[edit] Re-entry
After reaching the 100 km altitude, the vehicle will start the descent. For less then half the distance, the pilot will experience the effects of weightlessness. The ship must be kept with the RCS in a vertical position with the nose up. This process does not require an intense effort from the pilot since to some degree, even big altitude errors are allowed. When the ship encounters the first dense atmospheric layers the use of the RCS is not necessary,;the ship, due to the unique variable geometry system, will become auto-stabilized aerodynamically and inert. The maximum deceleration at reentry will reach -6.2 G for only 4 sec.
[edit] Recovery
Even though the variable geometry of the vehicle would allow a landing procedure on a runway, ARCA decided that the parachuted recovery system is safer from the following considerations:
- Iin the case of a trajectory error during the rocket engine powered flight, the vehicle could be deviated far away from the runaway
- The necessity of a runaway presence limits the flight corridor definition possibilities.
- The stress for the pilot is lowered because it suppressed the necessity of a runaway landing procedure.
- It offers the possibility to abort the mission in almost every sequence of the flight and to bring the ship safely at the ground.
The deceleration parachute will be extracted at a height of about 6.000 m and this operation is shortly followed by the main parachute extraction at 4000 m. The whole parachute system is placed in the front of the ship, at the bottom of the cabin. The landing in the sea will take place at a speed no higher than 7m/s. The stress over the pilot, from the rocket engine shut-down to the landing moment is reduced significantly.
[edit] Other projects
[edit] STRACAAT
In November 2005 ARCA succeeded to win a contract with the Research Ministry/Romanian Space Agency for the development of a rocket system with military applications. The contract was awarded for a period of 12 months.
ARCA’s military application rocket was presented to the Bucharest International Fair on October 3, 2006. The rocket financed by the government through the Romanian Space Agency- “SECURITY” Program, has a length of 4.1 m and is designed to fly with Mach 1.02 at sea level. The maximum flight altitude is 6.000 m. The main purpose of this project is to create a target able to simulate low altitude/high speed aggressor vehicles.
