Sooner or later, I figure someone will develop a spaceplane that takes off from places like Tampa International Airport, carries passengers and cargo to low Earth orbit, and flies back: either to the airport it came from, or the next stop in its flight schedule.
It might be a next-generation version of Dawn Aerospace’s Aurora, or an advanced Radian Aerospace model. But it won’t be Reaction Engines Limited’s Skylon. Developing their two-mode SABRE rocket engine ended up costing too much and taking too long.
I’ll take a quick look at Skylon. After that, I’ll take a longer look at Seattle-based Radian Aerospace’s PFV01 spaceplane.
PFV01, a prototype of Radian’s Aurora spaceplane, is the one that’s been making test flights near Abu Dhabi.
Closing the Book on Skylon
Looks like the Skylon spaceplane will never fly.
“Spaceplane developer Reaction Engines goes bankrupt”
Jeff Foust, SpaceNews (November 10, 2024)“Reaction Engines Ltd., a British company that has worked for decades on an air-breathing rocket engine for spaceplanes and other hypersonic vehicles, has filed for bankruptcy.
“The company formally entered administration, a process under United Kingdom law to allow for the restructuring or liquidation of companies in financial distress, on Oct. 31 after attempts to raise additional funding fell through. PricewaterhouseCoopers has been appointed as administrators of the company during the process, and under U.K. law has eight weeks to develop a plan to restructure or sell the company, or else liquidate its assets…”
[emphasis mine]
Can’t say that I’m surprised, but I am disappointed.
This is not good news for the 200-some folks working for Reaction Engines Limited (REL).
In 1989, Alan Bond, John Scott-Scott, and Richard Varvill started REL with a good idea.
They would have built a spaceplane that takes cargo and passengers from conventional airports to low Earth orbit. Their spaceplane would have rocket engines that get their oxygen from the atmosphere during part of the ascent.
They had a bit of a head start. Two of them had been working on the earlier British HOTOL spaceplane, which would have done the same thing.
I’ve been following REL, off and on, for decades. I think their “Synergetic Air Breathing Rocket Engine (SABRE)” is a good idea.
But I know just enough about science and engineering to realize that developing a rocket motor that uses atmospheric oxygen at subsonic, supersonic, and hypersonic speeds — switching to its onboard supply of oxygen after that — is pretty much the opposite of easy.
I think someone will develop engines like SABRE. Someday. It’s a basically sound idea.
But making SABRE work was too expensive, and was taking too long.
The odds that Reaction Engines Limited will not be liquidated are pretty much zero.1
I’m not happy about that, but I am convinced that something like Skylon will fly. Eventually.
Meanwhile, other outfits have been working on their own spaceplanes.
Radian Aerospace PFV01: Another Step
“Radian Aerospace begins tests of spaceplane prototype“
Jeff Foust, SpaceNews (September 25, 2024)“…The Seattle-based company announced Sept. 25 that it performed an initial series of taxi tests of a prototype flight vehicle it calls PFV01 at an unidentified airport in Abu Dhabi in the United Arab Emirates. The tests included what it called ‘short hops’ by the vehicle as it tested its handling characteristics for takeoff and landing. …”
I’m taking it easy this week, so I didn’t dig all that deeply into what Radian Aerospace has in mind. Instead, I’m taking excerpts from what Feff Foust of SpaceNews said.
Test Flights
“…PFV01 is designed to test the aerodynamics of the company’s proposed Radian One, a spaceplane that would take off horizontally using a rail sled system more than three kilometers long and reach orbit using rocket engines before returning to a runway landing. The vehicle, as currently designed, could carry up to five people and 2,270 kilograms of cargo to low Earth orbit and return with up to 4,540 kilograms of cargo….”
(“Radian Aerospace begins tests of spaceplane prototype” , Jeff Foust, SpaceNews (September 25, 2024) [emphasis mine])
I get the impression that Radian’s spaceplane design isn’t as ambitious as REL’s.
For one thing, their Radian One’s cargo capacity is 2,270 kilograms, compared to Skylon’s planned 15,000. For another, Skylon could have carried 24 or more passengers, while Radian One’s current planned version has room for five.
On the other hand, Radian Aerospace is still in business. Plus, they’re doing test flights with their prototype. Assuming that they keep going in this direction, I figure they can scale their spaceplane up — if or when it’s ready.
Something I noticed about Radian Aerospace — it’s an American company, with headquarters in Seattle, Washington.2
Washington state isn’t renowned for having vast expanses of flat land. But the state, and my country, aren’t exactly lacking in places where flying experimental aircraft — or spacecraft — would be comparatively safe.
Living With and Working Around Rules
I gather that Radian Aerospace ran the usual computer simulations before seeing what their scaled-down prototype can do.
Now, back to Jeff Foust’s article
“…The runway tests, he [Livingston Holder] said, confirmed those models. ‘It’s an important step,’ he said, ‘validating that the analytical models that we’re using match what we’re seeing in real life.’
“The company performed the tests in Abu Dhabi with the support of an unnamed partner there. The airfield where the tests took place was a ‘good, permissive environment,’ Holder said, that gave the company access daily….”
(“Radian Aerospace begins tests of spaceplane prototype” , Jeff Foust, SpaceNews (September 25, 2024) [emphasis mine])
Again, I’m taking it easy this week, so I haven’t ferreted out where that airfield is.
But my guess is that it’s not in Abu Dhabi itself: “good, permissive environment” or not.
That phrase does, however, tell me why Radian Aerospace opted for doing their flight testing so far from Seattle. Particularly since their PFV01 prototype doesn’t, at this point, include sensitive technology.
“…Radian largely avoided export control issues with doing the tests there since PFV01, powered by two jet engines, did not contain any space-specific technologies like rocket engines that would have been in the purview of the International Traffic in Arms Regulations (ITAR). ‘We’re keeping this to the airplane side of things because the airplane part makes it easier from an ITAR standpoint,’ he [Livingston Holder] said of the tests….”
(“Radian Aerospace begins tests of spaceplane prototype” , Jeff Foust, SpaceNews (September 25, 2024) [emphasis mine])
Now, I understand that rules and regulations can actually serve useful functions.
Regulations, for example, are supposed to keep manufacturers from selling airliners with pop-off panels — that pop off in flight.
I’m just glad that my country isn’t so overrun with regulators regulating regulations, that outfits like Radian Aerospace can’t legally develop new technologies. Even if, when it’s flight test time, our rules make getting “the support of an unnamed partner” and setting up operations overseas necessary.
Or, at least, make the folks at Radian Aerospace decide that they’ll save money by going abroad with their prototype. Despite having thousands of miles between their offices and the working area. And that’s another topic or two.
This is where I’d talk about authority, and how being both an American citizen and a Catholic affects me.3 But I’m keeping this post short. For me. Anyway, I mentioned the high points back in June:
“…Societies need folks with authority, legitimate authority. I’m obliged to show respect for the folks in charge. Those authorities should, in turn, show respect for the basic rights of the human person. (Catechism of the Catholic Church, 1897-1904, 1907, 1929-1933, and more)…”
(“Truth, Beauty, and the Evening News” , (June 15, 2024) Freedom of Speech, Lèse-Majesté, and “The Apotheosis of Washington”)
After the Radian folks have done runway tests with their PFV01, Jeff Foust’s article says they’ll move to “another airfield in the region”.
That’ll give them a longer runway for longer flights, where they’ll see how well the prototype handles: or doesn’t.
Rocket Sled —
I’ve seen the Radian One spaceplane consistently described as a “single-stage-to-orbit” (SSTO) launch vehicle.
REL’s Skylon would definitely have been an SSTO system, taking off from a conventional runway, flying to orbit, then landing on a runway after reentry.
Radian One will, provided all goes well, do the same; but instead of taking off from a runway, the spaceplane will get launched from a rocket sled.
After that, the delta-winged spaceplane will fly to orbit and return as a single unit. I figure that’s why the company’s website title is “Radian Aerospace — World’s First Single-Stage-to-Orbit Spaceplane”. That, plus a mix of hopefulness and marketing savvy.
Radian Aerospace and a Wikipedia page both describe “single-stage-to-orbit” launch vehicles which would be launched from rocket sleds.
I think I see why they’re using the term, since the part of the vehicle which leaves the ground is a single stage. But to me, systems using rocket sleds look like multi-stage rockets, with the first stage doing its job while connected to rails or similar guideways.
I also think Radian Aerospace’s approach to developing a surface-to-orbit transportation system is smart. It reminds me of the step-by-step process Max Vallier described, a century ago.4
— To the Stars
Sierra Space Dream Chaser and Dawn Aerospace Mk-II Aurora were in the news recently, too:
- SpaceNews
- “Radian Aerospace begins tests of spaceplane prototype”
Jeff Foust (September 25, 2024) - “Dawn Aerospace gets approvals for supersonic rocketplane tests”
Jeff Foust (July 11, 2024)
- “Radian Aerospace begins tests of spaceplane prototype”
- “Dream Chaser spaceplane 1st launch delayed until 2025”
Dave Adalian, EarthSky (July 7, 2024)
Dream Chaser will ride to orbit on a Vulcan Centaur. I haven’t confirmed it, but I’m guessing that it also could be fitted on something like the SpaceX Falcon Heavy, which is at least partly reusable.
The good news here is that Dream Chaser spaceplanes can be reused.
Dawn Aerospace may eventually build a spaceplane that goes into orbit, but the Dawn Mk-II Aurora flights will be distinctly suborbital.
Still, they will go past the Kármán line — a conventional lower boundary for “space” — so the Dawn Mk-II Aurora is a spaceplane.5
An ‘up’ side for the Aurora spaceplanes is that they’re designed to take off from conventional runways: no special rocket sled tracks needed. It’s not the REL Skylon, but it’s a step in the right direction.
Looking back, and ahead:
- “Something New: Polaris Dawn Commercial Test Flight”
(August 27, 2024) - “Marshmallows in Space! New Habitat Technology, Old Science”
(August 3, 2024) - “Boeing Starliner in Context: Apollo, Shuttles, and American History”
(May 11, 2024) - “International Space Station: Seven More Years”
(May 6, 2023) - “Commercial Space Services and Changing Times”
(April 29, 2023)
1 Flight physics, an aerospace company, and spaceplanes; very briefly:
- Wikipedia
- British Aerospace HOTOL (HOTOL: Horizontal Take-Off and Landing; a Rolls-Royce – British Aerospace (BAe) effort.)
- Hypersonic speed
- Reaction Engines (Founded in 1989, based in Oxfordshire, England; filed for bankruptcy October 31, 2024.)
- SABRE (rocket engine) (Reaction Engines Limited’s air-breathing/two-mode rocket engine design.)
- Skylon (spacecraft)
- Spaceplane
- Speed of sound
- Supersonic speed
- “Spaceplane developer Reaction Engines goes bankrupt”
Jeff Foust, SpaceNews (November 10, 2024)
2 Another aerospace company, and a spaceplane design that was worth trying:
- Wikipedia
- Wikipedia
- Part of my take on living in a less-than-ideal world
4 “Like a rocket sled on rails”:
- Wikipedia
- Max Valier (“This article needs additional citations for verification….”)
- Multistage rocket (Discusses the physics involved.)
- Radian Aerospace
- Reusable launch vehicle
- Rocket sled launch
- Single-state-go-orbit
- Spaceplane
- Radian Aerospace — World’s First Single-Stage-to-Orbit Spaceplane
radianaerospace.com - “Radian Aerospace begins tests of spaceplane prototype”
Jeff Foust, SpaceNews (September 25, 2024) - “Like a rocket sled on rails”, a phrase from “Convoy” , by C.W. McCall
Songfacts - Spaceplanes, and a good idea from the early 20th century
- “Radian Aerospace PFV01, Remembering Max Valier” (September 25, 2024)
- “Single Stage to Orbit, Eventually” (December 17, 2022)
5 Spaceplanes, and companies that make them:
- Wikipedia
- Dawn Aerospace
- Dream Chaser
- Falcon Heavy
- Kármán line (“…a conventional definition of the edge of space … not universally accepted….”)
- SpaceX
- SSC Demo-1 (AKA Dream Chaser Demo-1)
- List of Falcon 9 and Falcon Heavy launches
- Sierra Space
- Vulcan Centaur
- Dawn Aerospace “From Earth to Space / From Space to Everywhere Else”
- Dawn Mk-II Aurora – Rocket-Powered Aircraft — Dawn Aerospace
- Dawn Aerospace unveils their new spaceplane; the Dawn Mk-II Aurora (August 7, 2024; modified October 4, 2024)
- Dawn Aerospace unveils their new spaceplane; the Dawn Mk-II Aurora (July 28, 2020; modified June 24, 2024)
- Sierra Space
