Why Doesn't the Space Shuttle Deploy Its Wings During Reentry?

[mheslep]

I'm not talking about fishiong the Shuttle out of the ocean, but landing on a landing strip using a ram-scoop deployable wing rather than a rigid one.

Ok, what is your estimate of the the rough order magnitude size of an air foil that would touch down a 120 ton vehicle at ~ 5 ft/sec, i.e., slow enough for a dry landing?

 

[LURCH]

Actually, the Shuttle typically lands at over 300 ft/sec. Also, the shuttle would be considerably lighter without the rigid wings.

But the usual figure I've always heard was about 1 ft²/lb. o, I would guess that a 120 ton vehicle would need to be about 80,000 yd². Perhaps this company...

http://www.paraflite.com/pdfs/ADS%20DRAGONFLY%20PAPER.pdf

...could scale up their current project?

 

[mheslep]

Actually, the Shuttle typically lands at over 300 ft/sec. Also, the shuttle would be considerably lighter without the rigid wings.

I'm referring to the rate of descent. If the vehicle touch downs in water in can have a greater final descent rate.

But the usual figure I've always heard was about 1 ft²/lb. o, I would guess that a 120 ton vehicle would need to be about 80,000 yd². Perhaps this company...

http://www.paraflite.com/pdfs/ADS%20DRAGONFLY%20PAPER.pdf

...could scale up their current project?

Giving you what final rate of descent? Personnel chutes will put you down 10 ft/sec - too rough for a cargo carrying spacecraft . I am guessing you need 2ft^2. Even at 1ft^2/lb that's 850 ft on a side? A foil having > 1000 ft on the long side? That can't be deployed in the usual pop-it-into-the-air-stream manner.

 

[LURCH]

You've seen people land with personal chutes. They are not decending at 10 ft/sec when they touch down. Keep in mind that I'm not suggesting dropping the vehicle straight down like a mercury capsule, I'm talking about gliding down much like it does currently.

Deployment would indeed be a problem. Obviously, deploying the chute would have to wait until re-entry drag has slowed the vehicle to subsonic speeds. The size of the wing and the fact that it needs to open to a specific shape could necessitate the use of pyrotechnics for deployment.

 

[mheslep]

You've seen people land with personal chutes. They are not decending at 10 ft/sec when they touch down. Keep in mind that I'm not suggesting dropping the vehicle straight down like a mercury capsule, I'm talking about gliding down much like it does currently.

Common military (T-10, non gliding) chutes touch down at 22-24 feet/sec. Rule of thumb: 'chute touch down rate is the same as jumping off a 10' wall, or V=sqrt(2gh)=25f/s non gliding.
http://en.wikipedia.org/wiki/ATPS

Gliding must improves things, but I'm unfamiliar w/ how that system gathers and bleeds off energy.

 

[LURCH]

Right, that's why I specified ram-air rather than circular chutes like the military use (or the Mercury and Gemini capsules). But the scale of the thing is still somewhat daunting. As has been mentioned, the airfoil for the x-38 is referred to as the "largest in the world," and the one I linked to from paraflite is for 10-ton payloads, and will be the new record, I believe. Making one big enough to fly the Shuttle (minus its wings) is truly a new realm. I don't know if simply "scaling up" the current forms would function. But if it did, it would be lighter and cheaper than building the Shuttle with wings.

 

[DaveC426913]

I'm a bit confused. Will these ram-air chutes work to slow the shuttle from orbital velocity? The Mercury and Gemini capsules had a very large heat-shield surface compared to their size and mass, enough for aero-braking from orbit.

Without wings, the shuttle will be a very heavy missile moving at Mach 25.

 

[mheslep]

I'm a bit confused. Will these ram-air chutes work to slow the shuttle from orbital velocity? The Mercury and Gemini capsules had a very large heat-shield surface compared to their size and mass, enough for aero-braking from orbit.

Without wings, the shuttle will be a very heavy missile moving at Mach 25.

The idea proffered here was to use the old Apollo/Gemini style, but simple, large monolithic heat shield to brake from orbital velocity, perhaps jettison the shield, and then pop the chutes. I was thinking of some kind of large elliptical or rectilinear shape, a single piece that would be easy/cheap to construct, would not have to accommodate any complex or movable flight surfaces, and would not be exposed to debris strikes during ascent.