Long Range Stage Recovery

Recovering stages from far down range is likely to be on the agenda for several companies in the next decade or so. RTLS for the boosters or a first stage is a different proposition than collecting something from Mach several and a couple of thousand miles down range or so. The more performance that can be obtained from a stage that is economically recovered and reused, the less performance required from the upper stage. The less upper stage performance required, the less it should cost if expendable, or the more margin is available for recovery if reusable. A dense fuel upper stage released at Mach 17 should require a mass ratio of about 2 to reach LEO.

I vaguely remember discussion of an air captured stage from years ago and have sketched it out as I remember it.

aerorecoveryOn the left is the stage vertically ascending with some small fins to help stabilize it along with normal thrust vectoring. An aerospike is a prerequisite for this technique. If not for the other use in recovery, the fins would be hard to justify economically. On the right is the stage reentering with the fins operating as wings just large enough to enable a high speed glide. The tail surfaces fold out for the reentry. The fins/wings have a loading of 500 pounds per square foot to enable a glide at about 400 knots.

If this stage had a million pounds of sea level thrust and a mass of a million pounds, it should have an empty weight of about 50,000 pounds. The wing area would be 100 square feet with tail surfaces about a quarter of that. Fin/wing span would be about 16 feet plus the diameter of the stage. Mass of aero surfaces and controls estimated at 2,000 pounds.

This middle stage or parallel stage would reenter with the aerospike in the nose position absorbing the most of the heat and supplying the mass in the nose for stability. The blunt back end which was the stage front end before the upper stages will be high drag and a further stabilizing force.

A high speed tow aircraft hooks up to the ¬†gliding stage at fairly low altitude and tows it back to the launch site. Since the fin/wings on the LV are far too small to land, and there is no landing gear either, the means of safely collecting the LV from this point I don’t recall except that a lot of the ideas were way out there. It may have been a usenet discussion from the late 90s.

Does anyone remember the discussion? Has anyone worked out details that you know of?

The following two tabs change content below.
johnhare

johnhare

I do construction for a living and aerospace as an occasional hobby. I am an inventor and a bit of an entrepreneur. I've been self employed since the 1980s and working in concrete since the 1970s. When I grow up, I want to work with rockets and spacecraft. I did a stupid rocket trick a few decades back and decided not to try another hot fire without adult supervision. Haven't located much of that as we are all big kids when working with our passions.
johnhare

Latest posts by johnhare (see all)

This entry was posted in Uncategorized. Bookmark the permalink.

7 Responses to Long Range Stage Recovery

  1. Peterh says:

    If wings + tow aircraft can get the stage over the launch field, a parachute could return it to the ground. Though parachute landings of a large stage could be rough.

    A 400 knot runway landing should be possible with a long enough runway, but then you’re dealing with landing gear, maybe skids.

  2. johnhare john hare says:

    Parachutes were in the discussion, as well as foamed runways and aerial docking. Given the original concept of fin/wings sized for high speed glide when empty, but too small for landing. And minimal weight for the recovery system by offloading the fly back propulsion and landing system mass, it could get entertaining. I’ve a few half baked ideas and am wondering which of them are mine, and which are me remembering the discussion.

  3. Hop David says:

    It’s my belief that a RTLS or even barge landing reusable booster will have a more vertical ascent profile. This would be to avoid excessive boost back delta V expense.

    A more vertical ascent profile means increased gravity loss penalty as well as less horizontal velocity imparted to the second stage. In my opinion it is unlikely a reusable booster would impart mach 17 speed to an upper stage.

  4. johnhare John hare says:

    It was the recent Falcon flight that made
    Me remember pieces of a past discussion. I watch them from my yard about 60 or so miles away. This launch had a much more vertical profile from what I could see. The long down range unit would be a parallel stage or possibly a second of three. As you say, not a booster. The Mach 17 is just a number I threw out to illustrate the point. The sweet spot may be what SpaceX is doing now, or much farther down range with much more velocity. Whether we agree or disagree, I find the concept interesting enough to kick some ideas around.

  5. Ian Woollard says:

    Yes, the sweet spot for staging is generally reckoned to be much lower speeds; more like the Space Shuttle SRBs and Falcon 9 use.

    The reason is reentry shielding, at those speeds the reentry is free, whereas at higher speeds you need up to 15% of the landed mass to be shields. That comes directly out of the payload, and disproportionately so.

    The main advantage of tail sliding is probably lower ballistic coefficient; the landing speed is much lower, and you can sensibly combine it with vertical landing with much lower propellant use.

    You don’t actually need a tail either; the body and nose of the rocket acts as a pretty fair tail in its own right.

  6. johnhare johnhare says:

    That sweet spot would expend the center core of the F9H and any other high energy stages by other players indefinitely. Since this would be for middle stages doing well under orbital velocity, TPS should be considerably less than the 15% of an orbital vehicle. And since this is not the final stage, payload does not take a 1-to-1 hit.

    The concept is to get the highest velocity stage that can economically be recovered and reused. I.e. if Mach 13 requires no refurbishment and Mach 15 does for some particular vehicle, then Mach 12 could be the sweet spot, leaving the upper stage with a quite conservative mass ratio of 3-3.5 with dense fuels. An expended vehicle with 25% of its’ GLOW as net payload should be fairly profitable.

  7. Robert Clark says:

    Another possibility for recovery at high Mach is full wings, but such that they have high lift/drag ratio at hypersonic speeds.

    The shuttle has been deemed akin to a flying brick. It’s hypersonic L/D was only about 1, though it’s subsonic L/D was better at about 4.5.

    It is known how to get such high hypersonic L/D ratios. See here:

    http://www.aerospaceweb.org/design/waverider/waverider.shtml

    I’m working on calculations to show how this would allow RTLS even at high Mach, perhaps with a minimal fuel burn.

    Bob Clark

Leave a Reply

Your email address will not be published. Required fields are marked *