"Fake" is also very powerful, aerospace simulation products are very useful

Recently, the Indian Space Research Organization announced that if the weather permits, a landing test of a scaled-down reusable launch vehicle (RLV) will be carried out soon. If all goes well, India's full-scale RLV test may be carried out in 2030.

Reusable launch vehicle released by Indian media

Spaceflight is a high-risk business. To reduce the risk, a large number of spaceflight simulations have played a huge role. Using various scaled-down and simulated versions of spacecraft, researchers can find as many problems as possible in the design through low-cost flight tests, obtain test data in a near-real flight environment, reduce the risk of full-scale aircraft development, and reduce the overall cost of spacecraft development.

Let’s take a look at those aerospace “fakes” below!

Mini Space Shuttle

In fact, India's RLV is the "crown" of the spacecraft field - the space shuttle. According to the Indian Space Research Organization's plan, its mass is more than 70 tons and its total length is more than 30 meters. As early as 2016, India successfully conducted flight tests on a scaled-down version of the space shuttle under the general framework of the manned spacecraft program. The program is code-named RLV-TD, and its main goal is to complete suborbital flight tests and verify the design correctness of the space shuttle's aerodynamic shape, heat shielding system, flight control system, etc.

According to Indian media reports, the RLV-TD project took five years and the total investment was only 950 million rupees, or about 1.3 million U.S. dollars. Compared with the hundreds of millions of dollars in manufacturing and R&D costs of the U.S. space shuttle, it is incredibly cheap. From the appearance, the RLV-TD is simply a smaller version of the U.S. space shuttle, with a mass of about 1.75 tons, a length of about 6.5 meters, and a wingspan of about 3.6 meters, which is roughly the size of the SUV we drive daily.

In 2016, this scaled-down version of the space shuttle was placed directly on top of the S-9 solid rocket and entered an altitude of 64,800 meters. After release and separation, it continued to fly for about 770 seconds, reaching a maximum speed of Mach 5.5. However, the final physical landing of RLV-TD was completed on the water surface of a simulated runway about 450 kilometers away from the launch area. This is "one step away" from the space shuttle landing on the airport runway using its own landing gear.

Reusable launch vehicle released by Indian media

The test that India announced this year is to "make up for this step." It is reported that the scaled-down space shuttle will be hung under the helicopter and released from an altitude of 3,000 to 4,000 meters. After that, the test aircraft will refer to the landing trajectory of the space shuttle and use the landing gear to land on the predetermined airport runway.

Although India is ambitious in developing space shuttles, the thrust of its current rockets is far from enough to send the RLV, which weighs more than 70 tons, into space, and the future of full-scale testing in 2030 is uncertain. Obviously, India's road to manned space flight will be quite long.

Mini space plane

In the 1990s, the United States developed the next generation of space shuttles, officially known as the Unmanned Single-Stage Orbital Rocket-Powered Reusable Launch Vehicle, nicknamed "Venturestar". In order to reduce technical risks, the United States decided to first develop a prototype X-33 that was only 1/2 the scale of "Venturestar".

According to NASA's conception, the takeoff mass of the "Venture Star" is as high as 1,180 tons, and the dry weight accounts for only 10% of the total takeoff mass, including 5% for the main structure, 1.7% for the engine, 1.3% for the subsystem, and 2% for the payload. If the satellite is sent into orbit, the cost is expected to be reduced by 90%. However, this requires breakthroughs in a number of key technologies, and whether these technologies can demonstrate sufficient performance and reliability on full-scale aircraft has become a difficult problem facing researchers.

Therefore, NASA proposed to develop a smaller version of the X-33 first to verify a number of key technologies for the Venture Star, including the lifting body configuration with aerodynamic plug nozzle engine, lightweight composite material structure (such as hydrogen tank), heat protection technology and high-efficiency operation technology. It is reported that one of the test goals is to achieve three consecutive flights within 7 days, one of which is within 2 days.

According to NASA's public information, the X-33 is 20.29 meters long (21.73 meters with nozzle), 5.88 meters high, 22.06 meters wide, and has a launch mass of 129.4 tons, of which 95.3 tons are liquid hydrogen and liquid oxygen propellants. It will take off vertically, fly 1,500 kilometers at an altitude of less than 79,000 meters, and then land horizontally at the airport. The flight speed will be between Mach 8 and 13.5.

X-33 concept map

However, NASA obviously underestimated the technical difficulty. During the development process, the scaled-down space plane encountered problems such as the lightweight layered composite hydrogen fuel tank not meeting the standards and the linear aerodynamic plug liquid rocket engine technology not meeting the standards. The plan was eventually cancelled in March 2001. However, this mini space plane cost NASA $1.3 billion in trial and error, which was much cheaper than the originally expected prototype.

Mini spaceship

The current mainstream manned spacecraft is the spacecraft. During the research and development process, countries often use mini spacecraft to conduct experiments, and my country is no exception.

On June 25, 2016, during the maiden flight mission of the Long March 7 carrier rocket, a scaled-down return capsule of a multi-purpose spacecraft was sent into space. After about 20 hours of in-orbit flight, it successfully landed at the Dongfeng landing site in Inner Mongolia.

According to the development trend of the new generation of manned spacecraft, the mini spacecraft tested by various countries often explore new structures, new materials, new uses and other fields. For example, unlike the spherical or bell-shaped appearance of the "predecessors", the mini spacecraft are mostly in the shape of an inverted cone with a small top and a large bottom, and use a two-cabin configuration, focusing on improving manned efficiency and space utilization.

In addition, the return capsule attempts to adopt a double-layer design of metal structure + heat protection structure, in which the heat protection structure can be disassembled and replaced after returning to the ground, which is conducive to reuse. It is expected that the new generation of manned spacecraft will generally be partially recyclable models, which will save a lot of operating costs.

The mini spacecraft will not transport personnel, but will be equipped with aerodynamic measurement sensors to focus on monitoring data such as surface pressure, temperature, and heat flow during the scaled-down return capsule's re-entry into the atmosphere, obtain aerodynamic characteristic parameters, and collect valuable data for the aerodynamic shape design of the future manned spacecraft return capsule.

Simulated astronaut

In addition to "fake" space shuttles, space planes, and spacecraft, "fake" astronauts have also made outstanding contributions to the space industry. According to public information, my country's Shenzhou II, Shenzhou III, and Shenzhou IV spacecrafts carried simulated astronauts during their missions, and the Shenzhou VIII spacecraft carried out its first rendezvous and docking mission.

Simulated astronauts are also called body dummies. They look very similar to real people, with complete facial features, head, torso, and limbs. However, unlike the mannequins in clothing stores, they are essentially human-shaped sensing and detection equipment installed on seats. Their physique, mass, posture, center of mass, etc. are similar to those of real people. There are also human metabolism simulation devices and anthropomorphic physiological signal equipment to test the weight effect of spacecraft. Before real astronauts go to space, simulated astronauts have more advantages than animals. After all, their functions and physical signs are closer to real people.

Generally speaking, simulated astronauts must meet the requirements for wearing and removing space suits, and must wear space suits in the cabin according to the flight status of real astronauts. The suits are equipped with physiological signal test boxes, which can obtain simulated physiological signals such as electrocardiogram, respiration, body temperature, and blood pressure, and obtain physiological parameters similar to those of real people such as oxygen consumption and pulse in real time. After the host data is collected and transmitted to the ground, it can be used to assess whether the living environment in the cabin and the signal transmission link are normal, so as to verify the next manned flight.