If everything goes according to plan, next spring — perhaps in May — we will witness history being made. The Haas 2CA singlestage-to-orbit rocket, built by Las Cruces-based ARCA Space Corporation, will make its maiden flight from Wallops Island Flight Center in Virginia. In about five minutes, the rocket will climb high enough and accelerate fast enough to become the latest man-made object in low-earth orbit. If successful, it will be the first time in the history of rocketry a single-stage-to-orbit vehicle has achieved this goal. And it sets the stage for the next step in human exploration of space.
Last month, Southwest Senior reported on ARCA Space Corporation, its business goals, and its brief, yet busy, history. What has been driving its founder, Romanian-born Dumitru Popescu, and his team of rocket scientists is the idea a rocket can be launched directly to orbit, substantially reducing the cost of reaching space.
ARCA’s Haas 2CA rocket mostly looks like every other rocket you’ve ever seen — a 53-foot-long, white cylinder with a pointy nose at one end and an exhaust nozzle at the other. But the Haas 2CA doesn’t have the typical bellshaped exhaust nozzle we’ve grown used to seeing. It has this strange, wedge-shaped nozzle that looks more like a vegetable peeler than a rocket exhaust.
Instead of the usual bellshape, this engine uses what is called a linear aerospike nozzle. The “Why?” is simple. Issac Newton taught us — and we’ve heard this ever since Sir Issac said it — for every action there is an equal but opposite reaction.
To make a rocket fly, it has to have as much of its exhaust gases as possible flowing at high velocity in line with the rocket’s long axis. But at the throat of the engine, the combustion gases want to fly away in every direction. Thus the exhaust nozzle.
The bell-shape nozzle focuses the exhaust gases. As the rocket climbs out of the atmosphere, air pressure goes down. The exhaust plume wants to expand into a wider cone, but the mouth of the nozzle is a fixed diameter and doesn’t allow the expansion. It operates at peak efficiency only at a specific altitude. Engines operating in the lower atmosphere have shorter bells than those designed to work in vacuum. So, as the rocket gains altitude, the bell-shaped nozzle limits exhaust velocity and subsequent efficiency.The aerospike uses a different concept. It’s like cutting the bell in half and rejoining the two halves, back-to-back. With this engine, exhaust gases — pushing against the hard, inside wall — are focused just like the bell-shaped nozzle. But the outside has no wall and relies entirely on air pressure to focus the exhaust.
Now the math is pretty complicated, but the result of this kind of exhaust is, as the exhaust plume expands, the lower air pressure at the throat of the engine actually increases the exhaust velocity of the plume. Higher velocity translates directly into greater thrust.
An example might explain it better. SpaceX’s Falcon 9 rocket — currently supplying cargo to the International Space Station — generates 690,000 pounds of thrust at sea level and 738,000 pounds in space — and increase of 6.5 percent. The Haas 2CA has a thrust at sea level of 50,500 pounds, but it increases 31.5 percent to 73,800 pounds in vacuum. Although the two rockets are vastly different in size and payload, the aerospike engine in ARCA’s rocket is
considerably more efficient.
It’s also a much simpler design. It has sixteen individual combustion chambers comprising the exhaust plume. Velocity of each of those chambers can be throttled or varied, allowing the rocket to be steered so it remains on course. Rocket engines with bell-shaped nozzles rely on heavy, complex gimbals to maintain course.
The Haas 2CA uses kerosene as its fuel and hydrogen peroxide as its oxidizer, non-toxic chemicals the average person can buy for camping lanterns and cleaning wounds or bleaching hair.
The aerospike engine was not invented by ARCA Space Corporation. The concept was developed in the 1960s by NASA, who contracted with Rocketdyne Propulsion & Power to build and test it. Rocketdyne’s version of the aerospike used a similar fuel but liquid hydrogen as its oxidizer. To liquify hydrogen, the gas must be cooled to four degrees above absolute zero — or minus 455 degrees Fahrenheit.
Rocketdyne was unsuccessful in perfecting the aerospike engine because its composite fuel tanks experienced catastrophic failures from the extreme cold of the hydrogen. ARCA has avoided this problem by using non-cryogenic hydrogen peroxide.
ARCA also has developed a composite material for its rocket and begun testing it in 2002. Principally because the rocket uses chemicals at ambient or “room” temperature, the composite has not experienced a single failure. According to CEO Dumitru Popescu, they are the lightest fuel tanks ever used in a space vehicle.
So, while ARCA is testing and perfecting its vehicle for its upcoming maiden voyage, we will wait to see how well it succeeds in reaching space as a single stage to orbit. Following that, we’ll be able to watch this budding commercial space enterprise build and launch small satellites, not only capturing a share of a $5.3 billion market but also our imagination … and for young people, perhaps even fulfillment of their dreams.