supersonic flight

Jun 9, 2017

Is the door to commercial supersonic flight really starting to open?

Can a 'Super' Blackbird and a fast corporate jet perform demo flights in the next five or so years?

Ben Sandilands — Editor of Plane Talking

Ben Sandilands

Editor of Plane Talking

NASA wants this ‘quiet’ SST to start flying soon

There have been two Aviation Week stories by Guy Norris this week which might encourage even the most hard bitten pessimists about the near future of commercial supersonic flight into thinking a sliver of light had been shone into the decades of darkness that have characterised the topic.

The first, on moves to build an F-22 sized scaled model of hypersonic replacement for the long grounded SR71 Blackbird reports on some progress on the fiercely difficult issues of a combined cycle engine to deal with the totally different propulsion needs of an aircraft flying below and above the speed of sound.

It quotes a flight time in the early 2020s.

And, to be clear, it is a hypersonic rather than supersonic project. Something that is at least two orders of magnitude harder than supersonic flight, since it involves velocities three or more times faster than Concorde achieved, and skin temperatures even at more than 20 kilometres above the ground that would mimic those experienced for much shorter intervals by manned spacecraft re-entering the earth’s atmosphere.

The SR71 Blackbird flew at mach 3. The SR72 aims for mach 6. At no time, after it emerged from secrecy, was the design and technology of the SR71 considered remotely applicable to a future viable commercial airliner.

The second Aviation Week story is comparatively speaking, about a less spectacularly ambitious objective than mixed cycle mach 6 hypersonic flight. It would only do about mach 1.4 compared to a sustained cruise speed of close to mach 2 in Concorde, and from earlier accounts, be contemplated for an aircraft more the size of a corporate jet than a 100 passenger design that once regularly flew across the North Atlantic in about three and half hours.  This project would be assisted by NASA and could be going through its paces over a military housing estate in California (as the contract reportedly requires) also as soon as the early 2020s.

Both these stories require free registration with Aviation Week to be read in full.

They are also the work of another journalist, who has astonishingly good access and contacts in US aerospace, and who reports for owners who are making serious investments in quality reporting. Plane Talking is doing its bit to ensure that its readership taps into that resource, which is of a quality and level of specialisation unlikely to be found in this part of the world in a foreseeable future.

15 comments

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15 thoughts on “Is the door to commercial supersonic flight really starting to open?

  1. Jacob HSR

    Recent video by Irish engineer about new supersonic civilian aircraft:

    15 May 2017
    https://www.youtube.com/watch?v=R43gKMWAPco

    1. Dan Dair

      I’ll believe it when I see it flying.!
      I’ll not be holding my breath,
      but I do wish them & all working in this field the best of good luck.!

  2. Roger Clifton

    Above Mach 1 drag is linear with velocity, rather than squared, so fuel per distance would not change, other things being equal. But of course things are not equal in such extreme circumstances. It need only fly at an altitude of dense enough air to provide correct lift and thus a familiar amount of drag, so fuel consumption per distance might be made more economical.

  3. Jaeger

    Yeah, nah?

    I guess on an SST you could squeeze some more seats in where the toilets used to be.

  4. Roger Clifton

    With no solution in sight of the enduring problems of sonic boom and jetlag, the hypersonic vehicle might be better used for launching spacecraft. It need not have an integral sub sonic system if it were launched from the back of a 747 at altitude.

  5. Dan Dair

    I revisited Jacob HSR’s ‘Boom’ link…..

    I can see how a exec/biz-jet might work as an economic proposition.?
    God-knows, it never really occurred to me just how many 8-20 seat aircraft are already out there AND just how high & far some of them can fly.!!!

    The problem with the proposals that appear to be currently ‘on the table’, is that they seem to be too big for an exec-jet, but far, far too small for a viable commercial airliner.?
    The ‘Boom’ analyst in the ‘video’-link is saying about 30 passengers in an all-Business class format.
    I don’t have a problem with that, but how many routes are going to warrant flying an all business class airliner to start with, still less a supersonic one.
    There’ve been a whole bunch of Transatlantic airlines which have tried & failed to establish & sustain an all business class service, ostensibly between New York & London. This is one of the busiest medium-distance city-pairs, which has a substantial volume of passengers flying above the level of economy & a lot of those travellers are flying on corporate business.
    If you can’t make it pay on that route, I struggle to imagine where you can make all-business airlines work.
    And if you can’t make it work on subsonic routes, I struggle to imagine it working supersonic.?
    Will the kind of passenger that wasn’t prepared to pay a premium to fly in an all-business aircraft, pay even more to fly supersonic, all-business.? Possibly, but who is going to buy the aircraft in the necessary volumes to get it built & is it a worthwhile risk of capital, either to build it or to buy it.?

    In it’s heyday, Concordes only flew around 2000 seats in each direction, between Europe & New York in a week.
    I imagine that market is still there, at the right ticket-price.?
    If they can build a ‘more-economical’ SST (per passenger seat) with 30 seats, it seems sensible to actually create an equally-economical one with 100+ seats.?

    How many routes will support a supersonic feeder-liner.??????

    1. Jacob HSR

      Maybe LAX to NRT could work. If it has the range.

      or SEL to LAX.

      or maybe SYD to HKG.

      Is there a sonic boom upon slowing down? ie, take off from HKG, have a sonic boom over the ocean, then supersonic speed till reaching the QLD-NSW border?

      And is air turbulence less at higher altitudes? (Concorde flew 50,000 feet above the ocean)

      1. Dan Dair

        Jacob HSR,
        A sonic boom is a product of travel at supersonic speeds. (The current land-speed record holder produced a sonic-boom when creating that record.!)
        Travel at or above the speed of sound creates a shock-wave of the air displacement, which is what causes the sonic-boom.
        All the time the aircraft is at or above the speed of sound a sonic-boom will be generated, irrespective of whether the aircraft is accelerating or anything else.!

        In order for your HKG – SYD flights to work, you’d need to fly a few hundred kilometres North & West of the Australian coast. Sonic booms by civil aircraft are usually prohibited over land masses. (If they’re not currently in Australia, they soon will be should supersonic flights ever begin.?)

        As to turbulence, the higher you go, the less dense the air is, so consequently the less turbulent the air is, generally. On the other side of the coin, the less dense the air is, the less lift is generated by wing aerofoils, hence the ‘coffin-corner’ terminology, for subsonic flight around 40,000 feet.

        1. Jacob HSR

          Space X rocket produces a sonic boom upon landing. Yes, upon landing!

          Very strange. Search for 79VAdwjCL4U or US44dW-NCSI.

          No article mentions how many times a sonic boom occurs per Concorde flight. This video says that sonic booms occur many times per flight:

          XmDVvGNtgMg (at 5m32s)

          Astonishing! They should have done a demonstration to answer the basic questions – take off from AKL for ADL, reach supersonic speed when over the ocean, maintain supersonic speed till Ballarat, and land at ADL airport.

          1. Ben Sandilands

            Jacob HSR,
            This could take a long time if we want to go into the basics, but I wouldn’t start with any of those videos, but rather some basic physics texts, then work up through papers posted by NASA or similar.
            The sonic booms (plural) generated by Concorde and similar are continuous at more than mach 1. The primary boom comes off the large leading edges of a supersonic aircraft, but the trailing edges and other parts of a supersonic airframe will also generate sonic booms of various strengths. A sonic boom is over-pressure, it dissipates with altitude, and distance from the centre line of the trajectory. Everything I’m noting is a gross oversimplification of articles or studies I hope most readers are familiar with. When Concorde flies directly over land at mach 1.98 the continuous boom or shockwave is experienced for a fraction of a second and sounds like a loud whipcrack and as proven on a number of occasions, can collapse outhouses, frighten and cause fatal leg injuries to horses, and break glass, as happened in outback NSW in the 80s or 90s when an Air France charter given permission to fly across uninhabited parts of the country on a route from Denpasar to Sydney at supersonic speeds failed to go subsonic at an agreed point and did such damage. I wrote in up for The Bulletin, but am unaware of a digital copy having been made of the story. (Another Air France charter disregarded a condition that said no after burner assisted takeoffs toward Sydney from the then single long runway at the airport, leading to its permission to fly such charters being suspended for some time.)
            The boom carpet laid down by Concorde at altitude and maximum speed was around 80 kilometres wide, but the really insufferably loud and damaging boom was confined to a much narrower part of the track. Sonic booms are a normal part of spacecraft and satellite launches, and you will hear them called during live launch sequences by NASA and Space X at times. A sonic boom after liftoff usually occurs below 60,000 feet and is very focused given the climb attitude of the rocket, and occurs about close to the point where rocket exhausts go black because the hot particles of soot they ejected are unable to burn in the reduced oxygen available at that altitude and in the shortened time for external combustion to occur as the rocket gains momentum. It is common for the the sonic boom made by the re-entry of a controlled spacecraft to be heard prior to touch down. The Shuttle was well known in some Californian communities for the boom it generated on its way to Edwards. When Concorde was in trans Atlantic use it’s boom was sometimes reported by shipping and could also be detected from inside subsonic jets, although it was said to be so minor that inside such flights that most people wouldn’t notice it.

    2. derrida derider

      Supersonic all-business transatlantic flight could be more viable than subsonic all-business transatlantic flight. The reason is that business class’ only advantage over cattle class today is space and prestige, and corporates won’t pay much for that for middle management (top management can of course just ignore the beancounters, but they get a private jet).

      But if you’re actually saving 4 or 5 hours each way – well that’s a different business case, that might get a better hearing. The longer the range the less commercially unviable going supersonic is.

  6. Ben Sandilands

    Meteors,meteorites, and bolides all generate sonic booms, but you have to be right under a very large one to hear them, and you can also hear a strange noise that numerous skywatchers included on one occasion myself have experienced which you pick up not so much through your ears but body tissue. This is electro-acoustic energy which is generated together with a sonic boom by the sudden release of the kinetic energy from a large space rock hitting the atmosphere, and you feel rather than hear it. Numerous papers have been published into this effect, which is also associated with some high energy auroras at very high latitude locations.
    The https://en.wikipedia.org/wiki/Chelyabinsk_meteor injured over 1000 people on the ground in 2013 from the effects of a sonic boom that shattered windows and some older structures in the Russian city. There are numerous dash cam images of that event, and some very graphic security camera videos taken from inside schools and other places.

  7. zoidlord

    “Your comment is awaiting moderation”??

    What did I do wrong?

    1. Ben Sandilands

      Every now and then the software used by Plane Talking will challenge the authenticity of a free but registered visitor to the site. It happens to me about three times a year. It happens also to some users who run particular types of protocols on some setups, including workplace networks, or for whatever reason, arrive on this site via a different ISP than usual, or a different computer, and so on. It’s just one of life’s occasional irritations, but not on my top 10 list of things that really p*ss me off. I try to approve all comments stuck in the queue as soon as possible. Depending on where I am, and the time of day at location, or Telstra deciding it hates everyone, this can take too long.

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