Last time I have checked, there were no windows in SpaceX first stage...93143 wrote:Shuttle can't reenter at zero angle of attack. Nothing with windows in front can. Besides, most of the heavy-duty TPS is on the bottom.
Space X to build reusable launch vehicle
I never said it was. The wings were added to give the darn brik enough crossrange so the military (that then pretty much never used it) could do its black ops with it (has to be able to glide to friendly territorry at all times).The requirment for strong wingspar is not derived from reentry situation (after all, you can keep angle of attack at zero during reentry), but the spar has to hold all the weight of craft during any maneouvering. Any turn would put many Gs to the craft.
Either way, the shuttle still uses the friction of its body with the atmosphere for breaking. From what I understand the Falcon 9 first stage does not (would be be counter productive because that would bring it further downrange). The F9 first stage uses its engines for breaking. That is why I think that all sorts of rather lightweight and deployable wings should be possible on it too.
The most force you would get on it, is the air at terminal velocity or near that. That is not that much. It would be worse during launch though, but I dont think it would be bad enough to require heavy duty wings.
Also, the shuttle has to break down from Mach 25. The F9 first stage only reaches Mach5 (?). Lots of differences there.
Its cross range ability is to support runway lineup. Also the shuttle used S-turns and flares for braking. These turns and flares put big strain on the structure. But, at the end of the day it was a semi-guided brick. That thing dropped like a rock, and having seen the internal wing and root structure up close and personal last year on Atlantis during its flight preps, before it got stacked, I can tell you it was serious meat inside there. That thing is built strong. I don't know what the S-turn G-limit was off the top of my head, but I do know they sized the delta form and structure for some pretty serious stresses. Remember also that it was designed to bring itself down with a fully loaded cargo bay. That was part of shuttle's "Big Magic".
I am also wondering what you mean by glide path "black ops". Once they go re-entry, ther is no more mission other than to survive.
I am also wondering what you mean by glide path "black ops". Once they go re-entry, ther is no more mission other than to survive.
Once-around polar orbit. The black ops happen before reentry.
It never ended up getting used for a mission like that, but IIRC it was designed for it (among other things, of course).
And comparing speeds isn't all that useful, since the atmospheric density is so different at the altitudes involved. Shuttle didn't exceed 3 g during reentry. Any winged craft needs to be able to handle a substantial fraction of that just to work at all.
It never ended up getting used for a mission like that, but IIRC it was designed for it (among other things, of course).
And comparing speeds isn't all that useful, since the atmospheric density is so different at the altitudes involved. Shuttle didn't exceed 3 g during reentry. Any winged craft needs to be able to handle a substantial fraction of that just to work at all.
It had to be able to return to a "friendly" airport from pretty much anywhere in any situation. The shuttle could have contained materials and technology that was used during a black op or should under no circumstances fall into the hands of the Soviet Union (dont forget, it was the seventies). So it needed the crossrange to do that even when returning from an unfavorable orbit, or in case something went wrong, etc, etc.I am also wondering what you mean by glide path "black ops". Once they go re-entry, ther is no more mission other than to survive.
As I said, the shuttle was a failed design. One of the reasons is that it was designed to do too many things and it did none of them very well.
One of these things was doing black ops for the DOD and it did that so badly that the DOD never did anything with it anyway and rather used the EELVs. Makes you wonder how much better it could have been, had they known that from the start.
Of course the whole mess was due to failed politics... as usual.
Either way, you dont need such wings on an F9 first stage. You need a very limited cross range and the structure does not have to resist an environment as extreme as the shuttle was dealing with.
Remember, the F9 first stage only reaches Mach 5.5. That allone is a far cry from the Mac 25 that the shuttle had to deal with. In addition to this, it is save to assume that the F9 1st stage will use its engines for breaking. So the speed at which it hits the atmosphere will be very low. So low that it wont need much, if any heatshield. The stage will be much lighter too and will do the final descent with its engines. So it does not have to be slow enough for a runway landing.
So if they decided to add wings or some other structure that provides lift, it does not have to be anywhere near as solid as the shuttle wing structure that ladajo saw and it just has to provide enough lift and crossrange to make it the 250 something km back to the launch site.
In fact, it might only have to do part of the way and the rest could be done with the engines...
Between 1982 and 1992, NASA launched 11 shuttle flights with classified payloadsSkipjack wrote:One of these things was doing black ops for the DOD and it did that so badly that the DOD never did anything with it anyway and rather used the EELVs.
Launching paylods from an equatorial is no big deal. Converting from an equatorial to polar is.
Yes the shuttle was used to launch national payloads, this is well documented. But what I read above talked about re-entry missions and single loop polars from an equatorial machine. Kepler must be spinning in his grave. (Pun intended).
I would take a lot of gas to push it up, modify the orbit by 90 degrees, then remodify back 90 degrees (or so) to get a viable lineup run on a landing strip. Talk about making it hard.
This is where the X-37 is a load of fun. Just how much orbit adjustment legs does it take with it? Many amatuer bird watchers are finding out enough to keep them guessing where it is.
Yes the shuttle was used to launch national payloads, this is well documented. But what I read above talked about re-entry missions and single loop polars from an equatorial machine. Kepler must be spinning in his grave. (Pun intended).
I would take a lot of gas to push it up, modify the orbit by 90 degrees, then remodify back 90 degrees (or so) to get a viable lineup run on a landing strip. Talk about making it hard.
This is where the X-37 is a load of fun. Just how much orbit adjustment legs does it take with it? Many amatuer bird watchers are finding out enough to keep them guessing where it is.
Vandenberg, dude. California. Polar launch. They never actually used that pad, but it was there. What made you think the Shuttle couldn't do a polar orbit?ladajo wrote:But what I read above talked about re-entry missions and single loop polars from an equatorial machine.
Skipjack, you don't listen. The Shuttle only pulled 3 g during reentry, Mach 25 or no Mach 25. You need >1 g just to fly at all, and more to decelerate or maneuver; still more to maneuver and decelerate at the same time. And the Shuttle fuselage was a lifting body, whereas the F9FS is a simple cylinder. There wouldn't be a massive difference due to acceleration regimes. Vehicle mass, yes, but it should have been obvious that wing strength requirements would depend on that.
Last edited by 93143 on Mon Oct 31, 2011 5:56 pm, edited 3 times in total.
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GIThruster
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Variable geometry wings and thrust are never "lightweight". The boxes inside the F111, F14 and B1 make a huge portion of the crafts' mass and this is the reason we don't see more variable geometry designs. Likewise, the wings for the MV-22 are massively strong--they have to be. I find it most unlikely a scissor wing would be lightweight or especially reliable.Skipjack wrote:That is why I think that all sorts of rather lightweight and deployable wings should be possible on it too.
What was the reason for avoiding the obviously lighter weight parafoil? They don't look pretty? They could at least be used to present the first stage (and second) to the ground in a vertical position. Seems you'd need to stall a scissor wing to get it vertical.
Last edited by GIThruster on Mon Oct 31, 2011 5:56 pm, edited 1 time in total.
"Courage is not just a virtue, but the form of every virtue at the testing point." C. S. Lewis
No, you dont listen.Skipjack, you don't listen. The Shuttle only pulled 3 g during reentry, Mach 25 or no Mach 25. You need 1 g just to fly at all, and more to decelerate or maneuver; still more to maneuver and decelerate at the same time.
The F9 first stage wont have to decelerate and I wont have to maneuver with whatever lifting structure it uses (which maybe it wont anyway). It uses the engines for that.
Also, you understand that at Mach 25 the atmosphere hits the wings really hard, right? At terminal velocity you can put your hand into it...
You're still only talking about a factor of 3 at most, probably less due to shape differences, and I wouldn't be at all surprised if a factor of 3 could be made up by variable-geometry hardware.Skipjack wrote: The F9 first stage wont have to decelerate and I wont have to maneuver with whatever lifting structure it uses (which maybe it wont anyway). It uses the engines for that.
On the other hand, it occurs to me that Shuttle's wings were probably not designed for the nominal case, since certain abort modes (RTLS) involved some serious maneuvering. So there is that...
What part of "didn't exceed 3 g" did you not understand?Also, you understand that at Mach 25 the atmosphere hits the wings really hard, right?
Entry interface is extremely rarefied. The TPS gets hot, but the aero loads don't peak until down around Mach 3 IIRC.
Last edited by 93143 on Mon Oct 31, 2011 6:06 pm, edited 1 time in total.
In contrast to the F111, the F14 and the B1, the wings dont have to be big enough for the first stage to actually fly with it. It would just have to provide enough cross range for the thing to cover enough of the distance to the launch site that the remaining fuel and engine can do the rest.Variable geometry wings and thrust are never "lightweight". The boxes inside the F111, F14 and B1 make a huge portion of the crafts' mass and this is the reason we don't see more variable geometry designs. Likewise, the wings for the MV-22 are massively strong--they have to be. I find it most unlikely a scissor wing would be lightweight or especially reliable.
That is not very much. As I said, I dont even think you would need much of a wing at all. The stage is already very bouyant, you just have to give it some direction...
And I am sure that for that a very lightweight wing would be enough. Basically I imagine part of the hull to be doubled and simple scissoring out. Very lightweight thin structure.