18 thoughts on “Dreamchaser”

  2. Or a crew rescue vehicle in general. But in its current incantation, it would require some new regimen around NASA allowing one or more crew to return on a remotely piloted vehicle. Also would require on-orbit endurance testing to see how long one could be left in orbit and remain serviceable. But because of its unique landing capabilities, these should at least be given serious consideration.

  3. I agree, but specialty vehicles usually appear after the more common form of transportation, in case capsules… Once we have a few orbital facilities that will need both low G down cargo capability for some experiements and ambulance services.. this will be the ticket.

  4. I thought about arguing a bit about the “ability to land near hospitals” bit. My point along those lines is that I think the ability for computers, GPS, and deceleration control systems will improve precision to the point that a capsule will be able to land on a helipad. So landing on a runway won’t be all that spectacular.

    But I do agree about the lower g-load on entry, and I’ll add another point to yours, Rand; the cross range capability that will allow more orbit entry options.

    1. At some point we are going to need to learn how to handle “medical emergencies in space” while “in space”. A crew in transit to Mars ain’t gonna be able to abort to the nearest hospital when one of them develops appendicitis or breaks a bone or has a decompression accident. When the colonizers start talking about doing medical research on trauma care and emergency services is when we’ll know they are serious.

      (Seriously, why have I never heard any talk about research, in orbit, to determine the proper procedures for freefall surgery? Or other such procedures that will be necessary for people to actually live there beyond LEO tours-of-duty?)

      1. Seriously, why have I never heard any talk about research, in orbit, to determine the proper procedures for freefall surgery? Or other such procedures that will be necessary for people to actually live there beyond LEO tours-of-duty?

        For the same reason we don’t have a gravity lab. Because NASA has never been tasked to take space settlement seriously.

  6. I gave away my Milton Thompson book on the X-15, but there were some clues in there about landing a “brick”, i.e., an aircraft with a lift-to-drag ratio approaching unity.

    There is a general procedure for entering the landing pattern at an “uncontrolled” (no tower or other ATC direction), and the basic idea is to overfly the airport, make a descending turn to intersect the “downwind” leg of a landing pattern and then make a second descending turn into the wind to make your landing.

    Now a pilot generally wants to “square” this last maneuver, turning from downwind to based and then leveling the wings, and after that making the turn to final approach. Leveling the wings and looking over your right shoulder also makes your flight instructor very happy that you are not going to turn in front of making a direct landing without “flying the pattern.”

    The X-15 landing approach had something called “high key” and “low key”, and a quick search of the Web reveals that those are the terms-of-art for reference points in making an unpowered landing in an emergency when your engine quits. Well, X-15, Shuttle and now Dream Chaser, all of your landings are unpowered.

    So “high key” is where you overfly the airport to set up your landing pattern and “low key” is your downwind leg where you set up your turn to final and then land. Only in the X-15, high key, your initial reference in setting up a landing, is near 30,000 ft, whereas low key is about 15,000 ft AGL. So you overfly your landing spot up in the jet airliner flight levels, turn 180 degrees to your downwind to lose 15,000 feet, and then make a second 180 degree descending turn to descend another 15,000 feet to land. Let’s just say that you don’t “square off” that turn because you have a chase-pilot wingman or rigorously protected airspace that you don’t have to look out the right window for traffic.

    You see, you pretty much fly the same kind of pattern as a general aviation pilot landing on some grass strip someplace, only you have the nose pointed down in a dive-bomber attitude to maintain a stable flight configuration for maneuvering. It is only when you have “made the runway” that you raise the nose, a lot, to level off, and in doing that, you are “scrubbing off” speed in a hurry.

    So landing the X-15 was no different than landing a Piper Cherokee, only you worked with a different “set of numbers” for altitudes and airspeeds. Given that the Dreamchaser was released at such a low altitude, I don’t think they flew “the full pattern.” But you seem them entering a dive to achieve a steady-state flight configuration and then the call-out to “drop gear” and the landing flare to arrest the loss of altitude happens in very quick succession because of the rapid loss in airspeed. Just like with the X-15 and Shuttle — piece of cake!

    2. “Now a pilot generally wants to “square” this last maneuver, turning from downwind to based and then leveling the wings, and after that making the turn to final approach. Leveling the wings and looking over your right shoulder also makes your flight instructor very happy that you are not going to turn in front of making a direct landing without “flying the pattern.”

      Actually times are a changing. I was taught to fly the square pattern just like everyone else for the last50+ years.

      But a Navy instructor told me that the Navy now teaches a curved 180 from downwind to final with an occasional look over to the outside of the turn for anyone on a long final.

      So we went up in my RV-8 and he showed me how to do it. Then I practiced it until he was satisfied.

      The technique is beginning to catch on. There are debates about it – like that look to the outside for incoming traffic – but in many people’s opinion the pluses outweigh the negatives.

      This style is catching on.

      If you are flying one of the high drag biplanes, the curving approach seems to be even more beneficial.

  8. “The big deal about this is its potential for an ambulance from orbit, with its lower entry acceleration, and ability to land near a hospital. It will be a very useful capability.”

    To my knowledge, none of the several hundred people to go to LEO (or beyond) has urgently needed fast, low-G medical evacuation to Earth. No doubt the day will someday arise, but it seems to me that this eventuality is rather far down the list of life-threatening scenarios that might arise in space. Hence, I’m a bit surprised to see the author of “Safe is Not an Option” describing Dream Chaser’s ambulance potential as “very” useful.

    1. I’m always surprised the people misunderstand the point of my book. It’s not that we should be reckless, or not want safer systems; it’s that they should of a cost commensurate with the hazard and value of the mission, and we shouldn’t wait for them to come along to do things in space.

      1. I understand (and agree with) the point you make in the book.

        What I’m suggesting is that if historical experience acquired in sending several hundred people to LEO or beyond is any guide, Dream Chaser’s potential as an ambulance addresses only a small fraction of the risks to the lives of spacefarers. If it can be made into an ambulance at low cost, then, by all means, let’s do it. But I’m not sure it’s “very” useful.

        1. If it’s flying for other reasons, and can also be an ambulance, I think that’s great. I even think it’s worth spending a trivial amount of more money than SLS (because it would), for that purpose.

  9. The lower max-g of lifting entry is nice, but I think the larger cross-range is more important. That would enable you to get to a given landing point with less waiting in orbit.

    Longer term, lifting entry enables human-survivable return to Earth at very high speed, as much as 20 km/s. There, one would flip the vehicle so the lift vector is pointed downward. Lifting aerocapture is also possible.

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