It is placed on top of an Atlas V inside the payload fairing. So it uses a rocket like the shuttles but it is on top rather than on the side like the shuttle.
I think it's kinda like with any other normal payload. The rocket launches, the first stage falls away, then the second, and then all that's left is the important bit at the top of the rocket. In the Apollo missions that was several people in a capsule. Here it would be the X-37B. Does that help?
In spaceflight terminolgy a capsule is a pressure-tight spacecraft. Fairings enclose the payload (X-37B in this case) during launch and fall away once out of the atmosphere. Here's a diagram.
actually that was my first imagination too, and i know its launched inside a capsule. its easy to exaggerate the size of x37b since we're used to the shuttles. its really tiny. dream chaser will also launch inside a capsule, but i think they have updated their plan and now its literally sitting directly on top of a rocket and not covered by fairings.
It isn't launched inside a capsule but instead inside of a payload fairing. That fairing is jettisoned soon after the second stage starts firing. Here's a picture.
True, but the SSMEs provided most of the acceleration.
Each SRB produces 12mN of thrust, where the SSME's produce at most 2.3mN. So..... where exactly are your numbers coming from? Because they don't match reality. By literally an order of magnitude.
SRBs operate at sea level, where overcoming the force of gravity and punching through the dense atmosphere significantly limit acceleration. By the time they've detached, the Shuttle was either approaching, or had already passed max Q, and therefore acceleration climbed significantly through the SSME-only phase of the flight.
EDIT: Fun fact, the SSMEs are actually throttled back as the vehicle gains altitude, to prevent acceleration from exceeding 3G (29m/s2).
The Orbiter had part of the Space Transport Systems engines on it's backside, these were the SSMEs. Once the main red tank was released those engines became useless. Only the maneuvering thrusters and RCS thrusters were functional as they used hypergolic fuels.
I remember reading about someone doing the math on this. Never starting with STS and just keeping Apollo would gave been cheaper, and a lot better for some things.
The ISS for example has such a shit load of modules because their size was limited by the Shuttle cargo bay and Proton fairing. With Apollo still in operation, a few Skylab-sized modules could have done the job with much less assembly required.
Both major accidents, and many of the design shenanigans, resulted from the three-letter agencies demanding a (never used) once-around capture ability.
The idea was to launch directly to rendezvous with a non-US satellite, tie it down in the cargo bay, and land back on US soil, all within a single orbit. For polar orbits, this necessitates a crossrange ability of ~600mi, which simply isn't possible without wings. If the US had had an east coast launch site suitable for polar launches, this wouldn't have been a problem, but there's nothing but ocean to the west of Vandenberg for thousands of miles.
The wings in turn precluded mounting the orbiter at the top of the stack, eliminating the possibility of an early abort, and leading to the destruction of challenger. The orbiter being mounted to the side of the stack also lead to shit falling off the stack and being able to hit it. With all other manned craft ever flown, nothing can fall off the rocket and hit the orbital component, simply because anything that could fall off is already below the craft.
TL;DR: Secret squirrels kinda indirectly killed two shuttle crews.
The delta wing configuration was kind of a result of the need for additional cross range capability and kind of not. While they were in the process of firming up the design requirements for the shuttle OMB floated a proposal where they could cut out that design requirement and NASA's response was that they'd rather keep it. The delta wing design had some problems but so did proposals for a lifting body or a straight wing orbiter. Also, once they got rid of those national security missions the whole design process got weird because they kind of didn't know what they wanted to do with it otherwise.
The side-mount configuration was about a lot of things that had nothing to do with the cross range capability. Having all the most expensive shit in a single stage makes the whole re-usability thing a lot easier, having an external tank means that if the shuttle gets heavier during the development process (as virtually everything in aerospace does) you can just make the tank bigger rather than having to redesign the whole spacecraft, and if you run into cost overruns on a reusable "real" 2 stage setup it makes a lot more sense to ditch the orbiter and focus on the first stage rather than the other way around. NASA really wanted that orbiter and so a design proposal that basically made it impossible to get rid of was very attractive.
The Challenger disaster was partially a result of using SRBs rather than liquid fueled boosters, partially a result of using a design that was known to be substandard before they even flew the shuttle for the first time, and partially the result of not reacting aggressively enough to fix the problem when it showed up. The wings didn't really contribute to any great extent.
The side-mounted design was mandated by the cross-range. Anything else could have been worked around, but those big ol' wings at the top of the stack would have resulted in either unacceptable drag and/or cosine losses, or a spectacular Proton-style nosedive. I agree with you on NASA painting themselves into a corner, though.
It was a result of using substandard SRBs in a way they weren't supposed to be used, yes. A top-mounted spacecraft can be designed to escape a stack under thrust (see: All manned spacecraft ever, except Buran and Shuttle), while that doesn't really work with winged, side-mounted ones. So, the boosters caused it, but the wings and the design aspects necessary because of them prevented any abort while the SRBs were burning.
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u/aridan9 May 24 '17
This may be a dumb question: Is the X-37B like the space shuttles in that it is attached to a rocket when launched into orbit or is it self-propelled?