On December 20th, 2019 ARCA started the tests for its advanced aerospike engine LAS 25DA, for the water-based, electric Launch Assist System (LAS) rocket.

After reading the test data from the sensors for both classic and aerospike rocket engines, we clearly saw that the aerospike rocket engines are more efficient than the classic ones.

The tested aerospike engine has a dry weight of 184kg (405lbs) and it's rated to 25 metric tons of thrust. It is currently the world largest, being shy of only 10cm, (4 inches) in diameter compared with the largest circular aerospike engine ever built, Rocketdyne's 250K pounds of thrust from the middle of the 60s.

Classic and aerospike rocket engine comparison
ARCA tested initially the classic engine and then the aerospike engine on the same stand, using the same tank and same feed system, same pressures, the same sensors, allowing us to further find unprecedented answers regarding the direct comparison between the two engine configurations.

Having this capable installation available, we were able to draw an initial conclusion that the aerospikes are indeed better than the bell shaped nozzle engines, and not by a little, but by a large margin

For the first test we didn't want to push the test installation too far, and for the following tests we will increase work parameters until we will reach a specific impulse in the range of 60s. We can see that the aerospike had a 15% higher specific impulse but a question arises: From where this increase of specific impulse?

We do have some theories, but until we are not going to perform further tests and be sure, we don't want to publicly conclude at this point. We expect that this percentage to get even higher as the test pressure increases as the push effect of engine exhaust on the central plug will increase.

A "classic" bell-shaped nozzle works efficiently at only one flight level. After that point, the engine isn't properly taking advantage of the atmospheric pressure decreases as the gases are contained by the nozzle. An aerospike engine exhaust jet ideally expands from sea level up to space, ensuring superior efficiency at all flight levels.

Launch Assist System, an alternative to polluting rockets
Current rockets are using polluting, explosive, corrosive, toxic, carcinogenic propellants. At launch, a heavy rocket releases polluting chemicals into the atmosphere as much as 1 million cars running simultaneously.

ARCA created the Launch Assist System (LAS) an electric, water-based rocket that works as first stage, or booster for rocket launchers.

The water from the tank is electrically heated to 250C. When the water is injected into the engine, part of it flashes into water vapor.

By using water, such a system isn't only clean, but unprecedentedly safe and cost effective.

The root cause of current rocket's high cost is caused by propellants that are volatile, corrosive, cryogenic, toxic, requiring extreme safety measures, complex and highly expensive fabrication technologies and operations.

The rockets are using the majority of their fuel at take off when they are heavy. LAS can accelerate rockets to 3,000m (9,000ft) and Mach 2, reducing the polluting propellants with 25%, or increase their payload capability with 30%, using just water and electricity.

ARCA's Haas 2CA, initially designed as a Single Stage to Orbit Rocket, will reduce its polluting propellant mass from 16 to 6 tons using 18 tons of water instead, while keeping its payload capability.

How efficient is a water-based, electric rocket?
Like early electric cars, an electric water-based rocket is not as efficient as one using polluting fuels, but it's ideal as launch booster, or first stage, because it's able to generate high thrust at launch.

A first stage/booster makes its job as long as it contributes to the altitude increase and acceleration of its upper stage and this exactly what the Launch Assist System does.

Even if the specific impulse (the term that defines the efficiency of rocket engines) of the Launch Assist System is in the range of 60 seconds, which represents around four times less than a classic rocket using polluting propellants, this doesn't prevent LAS to increase the altitude and speed of the rockets it carries in a pollution free and unprecedented cost effective way.

See a video of test here

Read more about the aerospike and LAS technology in the White Paper here

Related Links
ARCA
Rocket Science News at Space-Travel.Com

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