New answers tagged

34

There are really two questions here: why is the main gear long, and why is the nose gear short? The main gear for most aircraft are designed to carry most of the aircraft's weight and therefore they're positioned near (slightly aft of) the center of gravity. The space shuttle lands at a high angle of attack (a very nose-up attitude) because of its delta ...


2

For the very early part of the shuttle program, leading up to the awarding of contracts, there's The Space Shuttle Decision (SP-4221). The same author wrote a Volume II, Development of the Space Shuttle 1972-1981, sponsored by the NASA History Office but published by the Smithsonian Institution; unlike Volume I, it does not appear to be available on the NASA ...


0

The trajectories are quite different between ascent and entry. Launch trajectories are designed so that the aeroheating is very little. Entry trajectories, without the advantage of minutes of powered flight like ascent, cannot avoid significant aeroheating. This aeroheating is several orders of magnitude more than ascent. The temperature of the heatshield ...


4

For what it's worth, the Saturn V did the same thing getting to parking orbit. Different vehicles with different propulsion and staging, but the outcome is essentially the same: Source: Saturn V Flight Manual. Note that the graph labels for the second (S-II) and third (S-IVB) stage cutoffs are incorrectly swapped. The source explains the third stage's ...


0

Let's look at the numbers. The acceleration is high at the start (full force!). It drops a bit at 40 seconds but then increases steadily due to mass loss. Between 100 and 120 seconds, there is a sudden drop in the acceleration. The two main thrusters are thrown off. From the lower value the acceleration increase continuously. In a somewhat linear fashion. ...


34

The drop in acceleration around 40s into the flight is the shuttle throttling down to reduce the aerodynamic load on the vehicle. It then accelerates when past this point. The drop in acceleration at 2 mins into the flight is due to the solid rocket boosters running out and being discarded. Acceleration then continues to build, as the thrust from the engines ...


22

The heating had already started to reduce as seen in this graph. To bailout (at least per the procedure), the Orbiter would have had to be subsonic. On a nominal entry the Orbiter would have gone subsonic ~26 minutes after EI. On STS-107 the main body breakup was at 969 seconds (~16 minutes after EI). So to make it to bailout, it would have had to hold ...


1

It's really important to take heed that any launch vehicle pitches continuously (i.e. its path gradually curves from vertical to its "horizontal" direction that will put it into LEO) whilst it is still in the atmosphere. The reason is that the vehicle is then using aerodynamic lift - the reaction of the atmosphere on its body - to change its ...


3

During the Apollo program, the Saturn vehicle was stacked on the mobile launcher platform. Thus, a platform was in use starting from the stacking of the S-1C stage. This table provides a detailed timeline for each Saturn V launch vehicle and the platform used: Mission Stacking start ML ML in use* Launch date Apollo 4 27 Oct 1966 1 1 9 Nov 1967 Apollo 8 30 ...


19

When the space shuttle goes out of the Earth's atmosphere, how does it then initiate going into the orbit? You're thinking of the climb out of the atmosphere and the entry into orbit as two separate operations, but it's really one continuous thing. It takes several minutes for even powerful rocket engines to accelerate to orbital speeds. Most of the ...


12

Two quibbles with the question: 17500 is roughly orbital speed in miles per hour, not km/h It's probably best not to discuss it in terms of "leaving the Earth's atmosphere". The shuttle never really did, the atmosphere in some form goes out very far indeed. However we can look at some times, velocities and burns. For STS-135 these are the ...


7

The mirrors (the commander had one too) were to allow the front seat crewmembers to see panels located out of their range of vision while wearing the helmets. Specifically, panels L4 (located to the left of and beside the commander) and R4 (located to the right of and beside the pilot). Panel L4 just had a lot of circuit breakers on it and wasn't normally ...


2

Whether the SRBs are called a motor or an engine is a kerfuffle, a pointless argument over terminology. One could equally well call them thrusters, which is a term I prefer. The working principles of a solid rocket motor, a liquid rocket engine, an ion thruster, a cold gas thruster, and even the hypothetical matter-antimatter photon thruster are one and the ...


16

The straight wing concept was perfectly workable. According to The Space Shuttle Decision, Max Faget preferred the straight wing approach primarily because it would optimize performance in the final subsonic approach-and-landing phase. The straight wing would also provide very little lift in the high-speed, nose-high reentry phase, meaning it would fall very ...


17

Mission Requirements for a spaceplane that are affected by its aerodynamic shape Cross-range capability Gliding range perpendicular to orbital plane on reentry. Otherwise, you have to wait in orbit for the earth to rotate your landing site into alignment with the orbital plane. Flying Qualities How easy the spaceplane is to fly. Landing Speed Safe ...


9

The design looks like it was descended from silbervogel, a German world war II project source The twin tails would have been to maintain control at high angle of attack but it appears the advantages of blunt body shapes for re-entry heating control were not understood giving it straight wings with sharp edges. The possibility of a delta design was only being ...


4

In the flight software, certainly not as a string. Strings are just nasty in this regard. Almost all flight software is written in one of three languages: Ada, C, or C++. All three of those languages support the concept of an enumeration. In the flight software code, it is best to the enumeration value by name (but not a string) rather than integer value in ...


3

Correcting a couple of misstatements in the question: Shuttle used hold-down bolts, not clamps Shuttle lifted off at 100% throttle on the main engines, not 104% Now, to the answer: Shuttle commander Jim Wetherbee was wont to say in the simulator when the clock hit T-31 seconds Nothing can stop us now...except a thousand things. He was right. Far, far ...


-1

Most of these control systems are written with MathWorks Stateflow. It's a simple way of implementing state machines where you can define behaviors for states and entry/exit conditions for each state. Typically, you will have different trajectory following behavior, throttle control loops, etc for each state.


7

Either. For the first part, you already answered your question. The main criterion was velocity, because the SSMEs on the orbiter are the second (and orbit insertion) stage of the Shuttle. There's no third stage to compensate for severe under/overperformance (well, there's the OMS, but there's only so much it can do because it doesn't pack quite enough punch ...


-1

So I've accepted that I need to correct my accelerometer readings for the accelerometer offset from the center of mass. The premise is wrong. There is no need to correct accelerometer readings. Rockets rotate slowly, if at all. After takeoff, it takes several minutes to pitch over from vertical to horizontal and the acceleration that results from this slow ...


-1

In this application, the phenolic resin is pyrolyzed in a non-oxidative environment beforehand and converted into amorphous carbon which can withstand pretty extreme temperatures provided it has a ceramic coating (e.g. SiC, HfC, etc.) for oxidative protection.


6

I couldn't find a public source so consider this a "hearsay" answer The shuttle first stage maneuver table consisted of 30 points The independent variable was velocity, not time.1 Simple linear interpolation was used. Source: Worked on DOLILU for two shuttle missions 1This is confirmed in the Ascent Guidance Training Manual paragraph 3.2.1


5

The Launch Vehicle Digital Computer (LVDC) in the Saturn V used quartic polynomials, four segments of them, for the pitch program, with the angle being a function of time since liftoff. Taken from Saturn V Launch Vehicle Guidance Equations page 4-14. F are the coefficients of the polynomials, $t_c$ is the clock time since liftoff and $\Delta t_f$ is a term ...


1

This answer on the Physics sit seems to sum up the maths pretty well: With the accelerometer A and the center of mass C we have $\vec{c} > = \vec{r}_C - \vec{r}_A$. $$ \vec{a}_C = \vec{a}_A + \dot{\vec{\omega}} \times \vec{c} + > \vec{\omega} \times \vec{\omega} \times \vec{c} $$ one can you the 3×3 cross product operator to transform the above into $$...


4

There was no escape system for shuttle so N/A there. See this Q&A Why not turn off the main engines while using the launch escape system on liquid fuelled engines? and especially the documents referenced in the answer, namely Technical Information Summary AS-501 p. 13+ (Emergency Detection System diagram) CSM15 Launch Escape System There's a full ...


6

(not an answer yet, I have yet to find SPL data for the SRBs) Thanks to the discussion and videos it does seem that the SRBs are louder. However, I had a vague notion that turbulence was important, and Reynolds number scales with jet velocity. The paper "Arenas, Jorge P., and Ravi N. Margasahayam. "Noise and vibration of spacecraft structures."...


11

Submitted as a somewhat subjective answer - you never know what sound editors did. These are two clips from the early shuttle IMAX file The Dream is Alive. This agrees fairly well with my experience of hearing the more white-noisy main engines followed by the louder crackly, snappy rumbling of the solids. There are significant differences between the sound ...


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