Think of that as a practical example of “defiantly helping.”
“Oh, yeah, User? I know how it’s spelled, and I know what you mean, and I’m going to fix it. SO THERE.”
[quote=“caligulathegod, post:12, topic:788406”]
I came across this on Youtube. It has a pretty good explanation.
[/QUOTE]How serendipitous. I literally just came across this video last night and watched it and was excited to share it when I saw this thread pop up a few minutes ago! And I got ninja’d!
[nitpick]
SerenDipitous
[/nitpick]
As already mentioned they used inertial navigation supplemented by ground-based radio navigation aids, then later by GPS.
The former Peacekeeper ICBM could achieve 90 meter accuracy after a suborbital journey of 6,000 miles purely through inertial navigation, with no terminal guidance or atmospheric steering whatsoever. It used a fluid-suspended beryllium inertial reference sphere: http://www.minutemanmissile.com/images/AIRS.jpg
I don’t get it.
And it could achieve that accuracy criteria with up to 10 independently targeted reentry vehicles (RV).
As noted by others, the reentry course that the Orbiter Vehicle followed was precalculated and controlled by flight computers (five independent IBM AP-101 computers interfacing with the engine and avionics controls through a complex system of input-output processors). This was not only for targeting but also to lose speed in a controlled fashion while preventing wing and skin temperatures from exceeding limits. To do this it performed a large series of S-curves, skip-gliding through the upper stratosphere and using compression drag from the leading carbon-carbon wing edges until it slowed sufficiently to be able to enter the troposphere and start using aerosurfaces to perform a controlled glide. The required precision precluded manual flight until the final gliding portion of the trajectory. The Shuttle did have a lot of available cross-range due to its large wing structure but was stodgy to fly at subsonic speeds; basically, once it on final approach it could only pitch and yaw by a small amount, so it relied on computer control to get it into the landing pattern for final approach.
The Apollo capsules (except for Apollo 13) landed with such precision that the original decision to put the recovery craft in the middle of the landing area was revised due to concerns that the capsule might actually land right on top of the carrier, and the recovery vehicles were then stationed just outside the pattern. Gemini was also quite accurate, and there was actually a version of Gemini developed for ground landing which deployed a Rogallo parawing which allowed it some amount of directional control, although little enough could be seen from the capsule forward windows that I can’t imagine a pilot being able to manually guide it into a runway.
Stranger
I recollected that adjustment took please early in the Apollo series, but the closest landing was Apollo 16 which came with 5300 yards (2.6 nautical miles) of hitting the carrier: https://www.youtube.com/watch?v=RsZZ7CvKIYs
That was without GPS or other modern navigation aids. They must have aimed away but chance trajectory dispersions cancelled out the offset.
To the OP’s point, today an Apollo-like capsule could probably land within 100 meters of a target. If they used steerable parachutes they could probably land within a few feet of a target.
The ocean splashdown concept was partially due to limited navigation and guidance accuracy, and the original Orion capsule envisioned a dry landing. However closer study showed a weight penalty for air bags which would be unneeded for a water landing, so they reverted to that.
The SpaceX Dragon capsule will also initially use a water landing but they eventually plan on a propulsive precision landing, which is a bit scary: SpaceX confirms first Crew Dragon flights will return to ocean landings – Spaceflight Now
Great answers. Thanks guys!
I think it’s some reference to the Straight Dope, but I was perplexed, as well, thinking at first I had misspelled the word.
[quote=“caligulathegod, post:12, topic:788406”]
I came across this on Youtube. It has a pretty good explanation.
[/QUOTE] That thing had the same glide ratio as a set of car keys.They’re probably attached to wires that guide them right to the zone. The same way the astronauts move around on the ISS.
Once NASA’s special effects computers got into the hands of Hollywood producers, all kinds of magical things could be done … like landing Space Shuttles with pin-point accuracy …
Shuttles landing with guide wires.
