Shuttle - Deployable Wings?

  1. mheslep

    mheslep 3,383
    Gold Member

    Just saw Endeavor return safely at night which inspired me to follow up on a question Ive long pondered: why not deploy the wings and vertical stabilizer after ascent or even late into re-entry in the lower mach numbers?

    The draw backs of dragging along the the aerial control surfaces on ascent and high mach re-entry are obvious after Columbia:
    1. Susceptible to damage from high velocity debris on ascent - foam/ ice.
    2. Drag
    3. Complex and difficult to maintain tiled heat shield required to conform to the aerial surfaces.
    In other words, when the shuttle is performing as a rocket, it should look like a big cylinder as does any other rocket, and start looking like an aircraft only when it is required to perform like one.

    The idea instead would be to mechanically deploy wings and stabilizer well into reentry at low mach when the aerial surfaces don't need to withstand high temperatures, say 60,000ft? Before then it would use some kind of monolithic heat shield as did the earlier manned missions which might be ejected. Even deploying the surfaces in orbit is still a big plus as that approach still saves on ascent drag and keeps the surfaces out of harms way.

    Storing, and then deploying the surfaces in flight must be difficult (impossible?). I know of some imperfect analogies - the F14 in flight and of course carrier aircraft in general that fold wings for storage. No doubt this has been considered. Can anyone explain why its not done?
     
  2. jcsd
  3. Danger

    Danger 9,879
    Gold Member

    I can't give you specific details or numbers, but I can say for certain that the weight of the actuator mechanisms alone would be enough to make the thing nearly un-launchable. There's also the matter of internal space to store the parts while they're not in service. Last, but not least, there would be serious fluid flow problems resultant of the various slots and ports needed for storage of the flight surfaces while retracted. An F-14 or any other swing-wing aeroplane doesn't face anything like max-Q.
     
  4. russ_watters

    Staff: Mentor

    The shuttle needs its wings for re-entry. They are what slow it down.
     
  5. FredGarvin

    FredGarvin 5,087
    Science Advisor

    The shuttle is already the most complex machine on the planet. I think that adding these features are going to add way too many places for possible failures. The return isn't worth the risk.
     
  6. Astronuc

    Staff: Mentor

    Storing the wing and tail would be problematic (compare wing/tail dimensions with fuselage), and for that reason alone it is not practical. Moreover movable/deployable wings/tail would require additional mechanical systems which would increase probability of failure, and that wing system must sustain heavy loading during the slowing down in the atmosphere. Thirdly, the thermal protection system must provide a tight, continuous seal otherwise hot gases may leak through and undermine the structural integrity of the wing/fuselage as was the case with the loss of Columbia.
     
  7. mheslep

    mheslep 3,383
    Gold Member

    Thanks for the replies all!

    This one I don't follow. The actuators on swept wing aircraft don't make them impractical. If there's some non-linear factor in scaling that up to the shuttle I don't see it. Also Im proposing to lose the heat shield weight by the time the wings deploy - so perhaps that counters the actuator weight a bit.

    Yes that might be show stopper.
    Why does there need to be any fluid flow during storage? I would think only during deploy and only then if you went hydraulic vs electric.

    Well that supports my point. I want to totally remove the aerial surfaces from ascent and max Q. That implies a much reduced drag coefficient on ascent and thus some substantial (?) savings in fuel. From Wiki:
    Well of course in general a re-entry vehicle historically does not need wings to slow it down, it only needs blunt body drag to slow it down as has been done in the past with Apollo et al. The shuttle happens to use its wings for that purpose in a series of high G turns.

    Yes, I'm suggesting wing storage does away some significant contributors to that complexity: that fragile, tile based heat shield which must be seen as an Achilles heal of the current design; I read now that management of the surface foam on ascent (which killed Columbia) is problematic - requiring telescopic inspection of the shuttle in orbit, etc, etc. A stored wing does away with all of that and use a traditional monolithic heat shield as has been done in the past.

    Likely so, though thats not clear to me. I was thinking the wings we be scissored, overlapped for storage underneath the fuselage.
    Yes, but there's experience w/ swept wing mechanicals and I'm proposing elimnation of much more complexity in return, I believe.
    Not if they don't deploy until late into re-entry. I suggest deployment a little higher than when the shoots popped on capsule re-entries.
    Yes exactly, replace all of that a single monolithic shield. Eject the shield as done w/ capsules exposing deployable wings.
     
    Last edited: Mar 27, 2008
  8. NateTG

    NateTG 2,537
    Science Advisor
    Homework Helper

    Honestly, it's hard to imagine why anyone decided to put wings on a spacecraft in the first place. Parachutes are well-understood, reliable, smaller, and lighter. For the weight of the wings, the Shuttle could easily carry a multiply-redundant parachute system. Considering what people on parachutes are doing these days, a system like that is probably going to be more flight capable than the existing shuttle anyway. I have no idea how important the wings are to the earlier aspect of the shuttle's reentry, or what kind of cost equation goes to retrofitting the shuttle with a parachute system of some variety.

    I guess that a parachute is exactly what you're describing - internally stored aerodynamic surface deployed only in the later stages of reentry. As a bonus it puts almost no restrictions on the shape of the craft for that part of reentry.
     
  9. mheslep

    mheslep 3,383
    Gold Member

    Here's a graphic of my foolishness:tongue2:
     

    Attached Files:

  10. mheslep

    mheslep 3,383
    Gold Member

    Yes I suppose aerodynamically thats an accurate description, not what I had in mind but yes. Certainly makes the mechanical situation simpler.

    The trouble with traditional chutes is, given the mass of the shuttle, I don't see a way to get to a soft landing on tierra firma. I know the Soviets did it, but that was with a ~monolithic capsule, no exposed rocket nozzles, etc. I cant see away to get to the soft touchdown w/ chutes on land w/ an orbiter mass.
     
  11. russ_watters

    Staff: Mentor

    No, the entire under surface of the space shuttle, which includes its wings, acts as a big aerobrake during the beginning of re-entry. You could, of course, design a system that doesn't require the wings, but remember that ballistic re-entry craft get hotter, experience higher g-forces, and are uncontrollable during re-entry. If the shuttle could be redesigned to behave similarly, it would take longer to slow down, meaning it would start with less deceleration and end with more deceleration - in a denser part of the atmosphere.

    Moreover, during liftoff, the wings do not provide a significant fraction of the drag. The SRBs and ET are the bulk of it at first, and once supersonic, the ET is almost all of it.

    It really wouldn't provide the benefits you are suggesting.
     
  12. russ_watters

    Staff: Mentor

    To land on a runway and reuse more of the craft.
    But are at the mercy of the wind and require a water landing and recovery - and you can't just lift a 727-sized object out of the water and drop it onto an aircraft carrier with a helicopter.
    Extremely, but they could be gotten rid of if the system were completely redesigned.
    for the shuttle itself, it simply isn't possible. It would require a completely different vehicle.
    Well, no, the restrictions are quite similar to the restrictions on earlier capsules. There is some complex aerodyanamics and thermodynamics at work there.
     
  13. mheslep

    mheslep 3,383
    Gold Member

    Ok, little or no reduced drag benefit. Doing away w/ that fragile tiled heat shield still stands though, as does less structural support required for wings that no longer have withstand max Q, and the overall safety benefits of not subjecting the wings to impacts during ascent. Also, I don't follow how the maneuverability gives the shuttle a high alt. re-entry advantage over pure ballistic? I assumed that was all to find a runway.
     
  14. Danger

    Danger 9,879
    Gold Member

    The STS uses redundant systems for everything important. That means that you'd have to have at least 2 sets of actuators per function. The individual ones themselves would have to be a lot beefier than those used on a military jet.

    I worded that sentence badly. I meant aerodynamic flow around the shuttle, not internal working fluids. It would be disrupted by deploying extra surfaces during flight.
     
  15. In my opinion the blended wing spacecraft is the most practical and cost effective. Like said before the shuttle is the most complex machine on earth.

    The blended body wings have many purposes: acting as airbrakes to slow the spacecraft down, the allow the shuttle to glide safetly, etc. If NASA engineer were to use the idea you have explained and drew, well then the should have just used the Saturn V with a payload. With that said, your idea whould not be capable of using the current and previous propulsion system the Space Shuttle has had since it was first launched in April 12, 1981. This includes the external fuel tank and the SRB's. The whole purpose of design the shuttle was to make manned space flight to places safe and efficient. By doing this the shuttle was born and the main benefit was that it was reusable.

    Also, if the shuttle was to have a wing deployment system such as foldable wings many mechanical systems would have to be designed so that the flaps and other mechanics that are involved in the wings can work. This is very crucial to the safe landing of the shuttle. Since the wings enable the shuttle to eaisly glide to the landing spot and be used over again. Also the wings on the shuttle do not pose a big problem of drag in take-off since the total thrust of the shuttle is 7,000,000 lbs or 31,000,000 N. So when the drag of the shuttle is factored in the wings effect on the total drag is very minimal.

    As for a parachute design finding the right materials that can be used to with the stand heat and the speed of the shuttle's reentry will take a lot of time and money. Also chances are a new parachute will have to be manufactured and replaced for each new shuttle launch.

    So in conclusion the design of the shuttle is perfectly fine right now. The shuttle will be able to serve the US Space program until it is retired and the new space vehicle in produced and flown. Although we have lost two shuttle's we are learning and making manned space flight safer and more efficient. These include heating elements in the external fuel tank to eliminate the build up of ice that caused damage to the tiles of the Columbia. So until the new spacecraft is used the shuttle is the best designed and most effective spacecraft we have. Hopefully the United States can keep our position as number one in space travel
     
    Last edited: Mar 27, 2008
  16. russ_watters

    Staff: Mentor

    I said controllability, not maneuverability (it doesn't steer during the initial decent, just regulates the decent). The shuttle regulates its deceleration and decent rates by controlling its angle of attack during reentry. I'm actually not certain about how much of a benefit this is, but I suspect this gives is much more flexibility in re-entry envelope (ie, different profiles due to different orbit altitudes). The ballistic craft were always on the edge - a little too steep and they burn up or kill the astronaut with g's (they maxed-out at about 12 g's during re-entry), too shallow and they bounce off and drift away into space.

    Now, the next shuttle, iirc, is going to be more of a lifting body than this one is, which will probably enable some of the improvements you suggest while retaining the ability to land on a runway and control the decent.
     
  17. mheslep

    mheslep 3,383
    Gold Member

    Doubling up on everything doesn't necessarily add to reliability. Obviously there are many important systems not doubled nor could they be: landing gear, ET, and of course - wings.
     
    Last edited: Mar 27, 2008
  18. DaveC426913

    DaveC426913 16,081
    Gold Member

    1] Why retract those surfaces at all? For protection? Then how do you protect the thing that's protecting them? It's still susceptible to damage.

    2] Sweeping wings are much more complex, much more prone to failure, much more expensive. But ultimately,the most expensive cost is in added mass. An airplane is simply not comparable to a rocket. A rocket's payload-to-delivery-system ratio is so low that science institutions compete vehemently to shave grams off their payloads.
     
  19. mheslep

    mheslep 3,383
    Gold Member

    Two reasons: 1. as an example recall the Saturn V - no oblique surfaces in the air flow, no damage worries on ascent even if there is a shower of detached ice raining down. 2. No complicated heat shield required to tailor fit to complicated flight surfaces.

    Well I expected that might be the case, but there are successful precedents so I've kept going. F14s didn't regularly fall out of the sky. Can you provide any more precision?

    Note that there's a great deal to be gained here as a trade off. The shuttle heat shield is composed of thousands of tiles, every one of them different and custom made to high tolerances. In near every mission some of them fail/are damaged and require manual replacement. The dam thing goes away with stored flight surfaces.

    Yes mass is an issue. There are trades there too: 1. Im guessing that wings that don't experience max Q can be lighter, 2. If mass is that tight Id still like to see the orbiters drag coefficient because that would improve w/o wings and save lift fuel mass. BTW, I also just saw a write up on the new 'impact sensor' system deployed recently in the wings - more mass that goes away w/ storage.
     
    Last edited: Mar 28, 2008
  20. Danger

    Danger 9,879
    Gold Member

    I'm going to return to this for a moment because I'm not sure if the significance came across the first time. Storing the wings internally would entail completely redesigning the internal systems in order to make room. That would include the engine gimbaling mechanisms, fuel delivery, and everything else behind the cabin.
     
  21. DaveC426913

    DaveC426913 16,081
    Gold Member

    Retrofitting is a completely different ball of worms.

    Let's assume that we're not talking about retrofitting an existing craft. Let's assume we're building a craft from scratch using mheslep's design but using existing technology**.

    **I'm trying to make the comparison with the shuttle a fair one. If we were designing a new craft today, it would be completely different - eg. it might have an aerospike, or might not be reusable at all, considering the criticism of the shuttle's intended usage. So, no new technology.



    Maybe the question could be qualified as: when we built the shuttle lo those years ago, how would it have been improved if we knew then what we know now? What if we'd given it depoyable wings?
     
Know someone interested in this topic? Share a link to this question via email, Google+, Twitter, or Facebook

Have something to add?