Reaction Engines’ Plans for a Mach 5 Point-to-Point Transport

In addition to being able to power a reusable, single-stage-to-orbit space plane, Reaction Engines’ SABRE propulsion technology could help to power a Mach 5 transport that would be able to fly from Brussels to Sydney in less than two to four hours.

The British company has designed a SABRE-derived SCIMITAR pre-cooled engine powered by liquid hydrogen that uses the company’s lightweight heat exchanges. The engine would be capable of sustained Mach 5 flight.

SCIMITAR Mach 5 engine. (Credit: Reaction Engines)

According to the company, the engine can:

  • Be designed for efficient subsonic and hypersonic cruise modes
  • Operate independently all the way from zero forward speed on the runway to Mach 5.5 i.e. they do not need assistance from other engines to get up to speed (c.f. scramjets need to be accelerated to Mach 3-4 before they will work)

Reaction Engines also has been studying a 300-passenger civilian transport capable of traveling approximately 12,500 miles:

The A2 vehicle, which is designed to be propelled by the Scimitar engine, has exceptional range (ca. 20,000 km both subsonic and supersonic) and is therefore able to service a large number of routes whilst simultaneously avoiding supersonic overflight of populated areas and the related sonic booms that can be heard on the ground. Its good subsonic performance enables it to service conventional subsonic overland routes.

LAPCAT concept. (Credit: Reaction Engines)

Reaction Engines is performing work on the project under the Long-term Advanced Propulsion Concepts and Technologies (LAPCAT) study, which is being 50 percent funded under the European Union’s Framework Programmes for Research and Technological Development 6 (FP6).

LAPCAT Facts & Figures
(Source: Reaction Engines)

Design mission

Brussels to Sydney (via North Pole and Bering straits to avoid supersonic overflight of Eurasian land mass)
Distance:18700 km
Flight time:4.6 hours (under realistic air traffic control conditions)
Reserve range:5000 km @ Mach 0.9
Payload300 passengers (plus baggage)

Vehicle Parameters

Gross take-off mass:400 tonnes
Fuel mass:198 tonnes (liquid hydrogen)
Fuselage length:139 m
Fuselage diameter:7.5 m
Wingspan:41 m
Wing Area:900 m2


Mach 0.9 cruise Lift/Drag 11.0 (5.9 km altitude) SFC 96.0 kN/kg/sMach 5.0 cruise Lift/Drag 5.9 (25-28 km altitude) SFC 40.9 kN/kg/s

Take-off sideline noise @450m 101.9 dBA

  • Alan

    This has been on REL’s website for several years, and was discussed briefly at a lecture Alan Bond gave at RAeS in London back in 2008 or 2009. Back then at least a major concern was whether the aircraft would be able to descend to a safe altitude in the event of a cabin breach within the time demanded by commercial aviation standards. There were also concerns about maintenance of the pre-coolers over a long burn period (not considered an issue for Skylon since the total engine burn time for a boost to orbit is much less than for a sustained cruise) and vulnerability to birdstrike. To that I’d add ground handling problems (many airports have trouble with the A380, and you can see on the video how much bigger A2 would be) and fuel handling, and I think this is best seen as a thought experiment.
    One thing I would be interested to see though is a trade-off between Skylon and a fully reusable 2-stage to orbit launcher based on the SABRE/SCIMITAR powerplant. But REL seem firmly wedded to the SSTO paradigm.

  • Paul451

    Argh! Autoplay video! Death to autoplay!

    I would think that it would be better to use a sub-orbital system. If you are capable of doing a reusable SSTO launch into orbit, and back again, you are certainly capable of an intercontinental sub-orbital ballistic hop. That shor

    Oh god, it’s on auto-loop too! Kill the monster, kill it with fire!

    That shortens the burn time to just launch/landing. It puts most of the flight above the atmosphere, eliminating fly-over restrictions and sonic-boom issues. And it shortens the trip to a 90 minute flight (say 2 hour with landing) anywhere in the world with a compatible airport/spaceport. And I suspect that the fuel cost will be virtually the same, since you’re not continuously burning the engines, and fighting drag the whole trip.

    Also, free-fall during the flight. Which is both a plus and an obvious minus, depending on the passenger.

  • Yep autoplay on page load is very annoying. If it continues I will have to remove from my daily read bookmarks.
    Good news source, don’t screw it up.

  • Harry:

    This isn’t my video and not my choice to do an auto play. I have no say over this. You need to talk to Reaction Engines. Every video on their website is auto play and it is very annoying.

    What I will do in the future is put auto play videos on the jump pages so they don’t bother people who frequently visit the site.

  • Greg Holden

    @Paul451. I think REL are suggesting a suborbital flight in this context (Unless I’ve read your post wrong…)

    I haven’t looked into this in any great detail, but looking at the video it seems they are suggesting the pre-cooler SABRE engine could be used for suborbital transport – LAPCAT concept. Plus the white livery suggests they aren’t coating the frame for this design in the heat reflecting material (needed for re-entry) they have rendered for the orbital SKYLON concept.

    And yeah, the autoplay is annoying, it went off playing that naff music in my office arousing the suspicions of my boss, but hey I’m quick with the pause button 😉

  • Paul451

    I believe the A2 concept is a hypersonic plane (Mach 5, continuous burn within the atmosphere.)

    I’m suggesting a ballistic hop, firing the engines only at the beginning to get up to speed, a suborbital arc above the atmosphere along the desired ballistic trajectory, sub-orbital reentry, then engine restart for a conventional landing. Faster, consistent with Skylon, skips sonic booms and over-flight issues for the vast majority of the route, even if the landing is inland.

    (Issues: Cabin integrity in a vacuum, radiation, heat-shield, engine restart. But I assume these need to be solved for Skylon anyway.)

  • Greg Holden

    Hi Paul,

    I see, you’re suggesting that as an alternative to LAPCAT (A2). I think REL have a concept like that in the pipline too involving SKYLON. I think REL are just trying to sell the adaptability of their engine here. I saw very recently on the REL website page about the SKYLON information that addresses the cabin integrity for passengers using a cabin housed within the cargo area of the SKYLON outer shell; it mentioned placing a pressurised box in which the passengers and crew sit (think of something like a cargo crate used for shipping) into the cargo bay of the plane. Of course there won’t be any windows.

    As for the heat shield I believe they have found a solution; which is why the SKYLON is always rendered in black, this isn’t just to look cool. I remember Alan Bond addressing this on a Space Show episode (sorry I dont have the link, I download to podcasts on my iPhone). Not sure about radiation or engine restart but I’m confident a couple of veteran Ex Rolls Royce engineers will have thought about this.

    The ballistic Point to Point concept you described reminds me of a book called ‘Sabre’ written by James Follett, first published in the UK in 1997, so not sure if the author got the idea from REL, or REL borrowed the name of the book for their pre-cooler engine. Anyway, the ISBN is 0 7493 2258 6 if you fancy a read. It’s a fictional disaster about the first launch of a P2P plane like SKYLON.