HAAS — Romania / USA

ARCA originally stood for Asociația Română pentru Cosmonautică și Aeronautică, and was founded in Romania as a nongovernmental organization — essentially, a nonprofit — in 1999, by Dumitru Popescu and pals. They made some progress with suborbital rockets and stratospheric balloons, going through several small models of rocket... with some design choices apparently having been made in ignorance of the “pendulum fallacy” which bit Robert Goddard back at the beginning of rocketry. And they started building a spaceplane in pursuit of the Ansari X Prize, which was won by Scaled Composites.

Then in 2015, they moved most of the outfit to New Mexico, as the for-profit ARCA Space Corporation. And for some reason, Popescu got arrested for fraud, but then was cleared on all charges by the grand jury. Apparently some guy that Popescu was talking up for a deal decided he was being scammed, but failed to prove it.

They started working on the first Haas rocket in 2008, with the nominal intention of competing for the Lunar X Prize. It’s named after Conrad Haas, a rocket pioneer who lived in medieval Romania.  They weren’t starting on a very strong footing for this, because their engines at that time were based on using hydrogen peroxide to burn solid bitumen. After a series of annoying failures they decided to bite the bullet and use a proper kerosene/lox engine.

The first Haas was to be launched from under a balloon, using three bitumen/peroxide stages. Then they decided that they couldn’t reliably handle balloons, and decided to launch from a plane. The second Haas was designed around a kerosene/lox engine called the Executor, which was to be made of carbon composites and ceramics and use an ablatively cooled nozzle, and which despite its nonmetallic design had a turbine, producing a chamber pressure of 45 bar. The Haas 2 was apparently designed to make some use of the turbine exhaust for steering, and would have had two stages, each with one Exector, with the second having an enlarged bell. The plan was to follow this up with a larger Super Haas which would have multiple engines.

The carrier plane would be ARCA's IAR 111, a supersonic seaplane powered by another Executor. It would carry the Haas 2 to about 17 or 18 km altitude, at a speed of up to 0.9 km/s — mach 2.6. So far, only a partial fuselage has been assembled.

They intended to flight-test the Executor in a single stage rocket called the Haas 2CA, which they believed should be light and efficient enough to reach orbit without a second stage, with up to 100 kg of payload.

But then things got interesting. They decided to try making an aerospike engine, and as far as can be determined from their current promotional content online, they found this so exciting thay they are shelving the previous Executor engine.

What the heck is an aerospike? It’s a piece of aerodynamic trickery that replaces the bell part of a rocket engine with a concave point or wedge shape which confines the rocket exhaust on only one side, with confinement on the other side being essentially provided by ambient atmospheric pressure. This has two claimed advantages: first, that unlike a bell, it self-adjusts to work optimally at many different altitudes, and second, that at low altitudes it needs less fuel. But how the heck is it supposed to be any good in full vacuum?

Many space outfits have experimented with aerospikes, because on paper they offered the tempting possibility of getting to orbit with a single stage. They were even considered for the Space Shuttle’s main engines, but nobody ever quite got to the point where they judged the result preferable to a conventional rocket engine. Then the VentureStar program was going to use one for a replacement shuttle, which would have made a single-stage rocket make sense (without reusability, there’s not much point)... but both Lockheed and the NASA administrator of the time overpromised how cheap and easy it would be, and the program ended up getting cancelled over issues which, in hindsight, were probably quite solvable. Aerospikes have largely been sitting unused ever since, but now ARCA thinks the time is right.

Their new plan for the Haas 2CA is for a “linear” aerospike — that is, a wedge with a straight back edge as used in VentureStar, as opposed to a ring shape or a single point, as in some other proposed designs. It will have eight little combustion chambers on each side of the wedge. Throttling the ones near the corners provides steering. Oddly, they’ve regressed to using peroxide instead of lox, though the fuel is still kerosene. They’ve also regressed to using pressure-fed combustion. They now claim that this engine is what the Executor name refers to. But the really bold claim is that they expect this thing to launch small satellites for just $1 million per flight. Maybe the regression is justified by extreme cheapness.

Or maybe they never had the capability of building a cryogenic engine, and the original Executor was a paper fantasy. I have found no evidence to the contrary. I would be a lot more excited about this innovative and futuristic rocket if the company had even once succeeded at anything else it tried.

If you want to follow their progress, they put out a Youtube series called The Flight Of The Aerospike, which is already over twenty episodes. So far, this shows them building a “Demonstrator 3” suborbital aerospike, which is based on using peroxide as monopropellant — a reaction which doesn’t even produce temperatures hot enough to require metal nozzles. In short, the fabrication work they’re now doing has almost nothing in common with making the promised orbital engine! I do not have much confidence in this company. They are obviously many years away from building anything orbital.

One problem with aerospikes is that it’s difficult to cool the nozzles and combustion chambers. The best mitigation for this may be to build the engine on a very large scale. But ARCA intends to keep this engine small, and so far, they are just avoiding the heat issue by using weak-ass propellant. This makes them even more unprepared.

Lately they’ve started hyping yet another novel idea: an optional booster stage to increase the capacity of the Haas. This stage wouldn’t use any chemical fuel — it would simply use steam! Apparently the water would be heated electrically (with solar power) before launch. They called this the Launch Assist System, or LAS. Then they started calling it the EcoRocket.

At some point they moved back to Romania. Then in 2022 they announced a grandiose plan which they dubbed EcoRocket Heavy, in which hundreds of EcoRocket steam tanks would be bundled together as a first stage for dozens of peroxide upper stages, which would then launch something out to the asteroid belt... where they somehow expect to retrieve metals like platinum. That does it: there is no longer any possible way to take these guys seriously.

Haas 2CA: mass 16.3 t, diam 1.5 m, thrust 225 kN, imp 3.1 km/s, pressure-fed (kerosene and peroxide)?, payload 0.1 t (0.6%), cost hopefully $10M/t.