Aren't parachutes much cheaper than rigid wings?
The X-38 is interesting; looks like NASA also would like to get rid of wings. However it doesn't prove much in the way of 'chute or foil landings: Wiki says the airfoil used for the little 12 ton X-38 was the 'largest ever made'; 12 tons is a payload to LEO for the current 120 ton orbiter, and by size almost two X-38s could fit in the orbiter bay. The scales aren't even close. Think 747 scale when considering the Orbiter. The goal of the discussion wasn't to discover some freakishly expensive alternative, rather Im more interesting to discover the boundaries of practical improvements over the current design which, despite its problems, works.Honestly, it can't be that hard to pull the shuttle (or something shuttle-sized) out of the ocean. If nothing else, it could be lifted on some kind of bladder and towed to a port. It's probably more difficult to get it to float in the first place.
The x-38 prototype - which is big, though not as big as the orbiter - has made parafoil landings on land.
...This would amount to a deployable wing, on which the craft could glided to a landing strip much like the current landing method, but at much lower speeds in a much more forgiving vehicle...
Yes but as Russ Waters pointed out in #11 its probably impractical to fish the shuttle out of the ocean.
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?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.
I'm referring to the rate of descent. If the vehicle touch downs in water in can have a greater final descent rate.Actually, the Shuttle typically lands at over 300 ft/sec. Also, the shuttle would be considerably lighter without the rigid wings.
Giving you what final rate of descent? Personnel chutes will put you down 10 ft/sec - too rough for a cargo carrying spacecraft. Im guessing you need 2ft^2. Even at 1ft^2/lb thats 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.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...
...could scale up their current project?
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.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.
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.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.