# Tag Info

64

The O-rings and the temperature were only the last in the long chain of blunders, and that had little to nothing in common with reusability. The construction of the SRBs wouldn't be much different with no reusability in mind. Indeed, SRBs of very similar design are to be used in SLS, and they are not intended to be reusable. About the most important factor ...

60

No. Compare Space Shuttle Launch Countdown. The SRB fire command and the hold-down fire commands are issued at the exact same time. The delay of about 6 seconds (note: each SSME is started at a different time, all 0.2 seconds apart) is to ensure that each of those engines are up to full throttle without errors prior to launch (which is called a Redundant ...

50

I don't have an immediate citation handy, but the answer is no. The SRBs were powerful enough to overcome the hold-down studs. That said, the same signal was used to blow the nuts on the hold-down studs and ignite the SRBs. Once the SRBs light, the vehicle is going somewhere.

43

Specific impulse is not the only measure of a rocket. For the case of the SRBs, high thrust is much more important than high specific impulse. In this case, you want to look at the heat of formation for carbon dioxide vs aluminum oxide. Carbon dioxide has a heat of formation of roughly -390 kJ/mol, compared with roughly -1670 kJ/mol for aluminum oxide. ...

43

The squat end of the spectrum has little to do with solids versus liquids and everything to do with aerodynamics. Spherical tankage is most weight-efficient, so you'd expect squat stages in cases where aerodynamics don't dominate such as your Mars Ascent Vehicle (flying where atmospheric drag is on the order of 1% what it is for Earth ascent) or the Apollo ...

42

Long March 11 is a cold-launched rocket, based on a concept popular with military rockets. A gas charge is generated by the launch platform (often using a chemical gas generator) to eject the rocket from the launch platform before engine ignition. This saves the launch platform from having to manage hot exhaust gases, and reduces wear and tear on the launch ...

31

No, a quick calculation yields a $\Delta v$ of about 4.6 km/s and you need about 9 km/s to get to low-Earth orbit. You'll lose a lot of that velocity to aerodynamic drag as well as the vertical portion of the flight, so a rough estimate of the final speed at burnout would be somewhere around 3 km/s -- or about 10,000 km/h. Using the specifications from the ...

29

SRB Ignition SRB ignition can occur only when a manual lock pin from each SRB safe and arm device has been removed. The ground crew removes the pin during prelaunch activities. At T minus five minutes, the SRB safe and arm device is rotated to the arm position. The solid rocket motor ignition commands are issued when the three SSMEs are at or ...

28

Do we get to pick our assumptions? I don't see how to answer this otherwise. I'll assume the hole kept growing at a "slow rate" and the booster didn't come apart. (If the booster came apart, the result would not be much different from what actually happened). (Note many people were suprised back then that the booster didn't come apart with that size of hole ...

26

Not reusability per se, but design and politics. The competitor to build the SRBs for the Shuttle program was Aerojet, and their design was monolithic. In other words, no segments. Aerojet was actually selected as the winning contractor but the NASA administrator Fletcher overrode this and gave it to Morton Thiokol. Aerojet had already built an awe-...

23

It's a quenching probe. After burnout of the booster was confirmed, a CO2 fire extinguisher was moved into the nozzle area to inject carbon dioxide into the booster to kill any remaining fire in order to preserve the systems in their condition at burnout, allowing for a detailed study of the components of the SRB.  Source: http://www.spaceflight101.net/...

21

Yes, several of the previous shuttle launches exhibited erosion and/or "blow-by" of the SRB O-rings, starting with the second flight, STS-2. Much has been written about the failure of NASA and Thiokol management to recognize the severity of the problem and respond appropriately. The Rogers Commission report covers a lot more than the O-ring problem, but is ...

20

Could the shuttle wait out the whole burn of SRBs on launchpad in case of a problem on launch? No. The question seems based on the assumtion that something (the hold-down bolts perhaps) could hold the stack down while the SRBs burn out, while being immersed in the 3300 degree Celsius exhaust for about 128 seconds. Note that during this time, while the hold-...

20

You might be interested in the tool called cpropep. This allows us to gain basic performance indications for different fuels by solving the physics behind it: chemical equilibria and expansion/compression. So how does $NH_4ClO_4 + Al$ perform against $NH_4ClO_4 + C$? First we feed it the approximate conditions: Chamber temperature: anything (calculated ...

19

The Ares 1-X used stock Shuttle program SRB thrust vector control (TVC) - hydrazine fueled power units drove hydraulic pumps which powered actuators that could tilt and rock the nozzle, which incorporated a flexible bearing in its design. (Pictures from "Space Shuttle", Jenkins, 1992 edition p.263 and here - p 2.13-48 of linked PDF) However, unlike the ...

19

The SRBs have smaller solid separation motors, 8 on each, which simultaneously fire to push the boosters safely away from the orbiter/ET. Here's a video showing them in action -- they're powerful enough to give the external tank a good scorching. You can see the separation is designed to turn the boosters slightly outward so any remaining SRB thrust takes ...

19

Wings, engines to fly back to the launch site, and landing gear are heavier than parachutes. Using this design on the SRBs could have resulted in a significant payload to orbit reduction (every 10 pounds added to the SRBs resulted in 1 pound less payload that could be carried to orbit). However, this was studied for the case of liquid fueled flyback ...

19

Meet the Ariane EAP (Étage d'Accélération à Poudre, "Solid Booster Stage"): what are the (presumably eight) circular spots on the external nozzle-like protrusions at the bottom of each of the (presumably solid rocket) boosters on either side of the main engine? They are the business ends of the fusées d'éloignement, or separation motors, which ...

17

No, they don't have sufficient thrust when they're jettisoned to catch up with Space Shuttle accelerating away: The SRBs are jettisoned from the space shuttle at high altitude, about 146,000 ft (45 km). SRB separation is initiated when the three solid rocket motor chamber pressure transducers are processed in the redundancy management middle value ...

16

SRBs have a very high thrust to weight ratio, even if they have an only modest ISP. That makes it complementary with LH2/LOX systems that have a relatively low thrust. Early on acceleration is almost as important for over all efficiency as exhaust velocity. For the first few hundred m/s of $\Delta v$, a combined metric of ISP and propellant density, called ...

16

The Ares I-X was a modified STS SRB with with an upper-stage simulator. So far as I know, this was the only standalone launch of SRB hardware. Even the original SRBs were not flight tested before manned launch. The Ares I-X flight had an apogee of 46 kilometers, less than half the 100 kilometer altitude of the Karman line, which is considered the edge of ...

16

NASA was the most concerned with the thrust oscillation happening near and on depletion of the first stage fuel, roughly 105-115 seconds into the flight after liftoff and just before first stage separation (see Ares I-X Mission Profile below), as it was shown by the computer modeling and early design analyses of the Ares 1 rocket.     This ...

16

This is referred to as 'kick stage' motor and is commonly used. One example being Star 37. A larger Star 48 is what sent New Horizons on the way to Pluto

15

Technically, it was the O-rings, but that was not the root cause. The root cause was a poor culture at NASA. The technical solution was easy: Don't launch on that cold of a day. In Florida, even in late January, all you have to do is wait a day or two and temperatures will once again be balmy. Technically savvy people knew well of the O-ring problem in cold ...

15

The answer to the question is an ancient philosophical question: Ship of Theseus. As Organic Marble mentioned in his comment which could have been an answer: The SRBs were made up of segments, and the reuse was at the segment level. The obvious lower bound for number of SRB segments produced would be eight: four SRB segments per side per launch. We can ...

15

My reading of the function of the SRB manual separation control is that it would not actually trigger a separation while the boosters were firing (bold mine): SRB separation is normally performed automatically by the onboard GPCs; however, the flight crew can command separation through use of the SRB separation switches on panel C3. The SRB separation auto/...

15

SRB segments for reference while reading this: The boosters were towed back to KSC by ship. This crane then lifted them out of the water... ...and placed them on this dolly which could move them into Hangar AF. The SRBs were washed down and hazardous materials (unfired ordnance, etc) was removed. After an inspection, the dolly moved the SRB into a ...

14

Image source The booster has two kinds of joints between its segments, field joints and factory joints. The booster parts shipped to KSC were made up of two segments joined by factory joints. At KSC, these parts were put together using the field joints. There are three field joints and seven factory joints in a Shuttle SRB. Image Source Both kinds of ...

13

There was certainly a risk that the boosters could collide with each other, once they separated they were essentially just big pieces of pipe. The chance of it happening was extremely low though. At separation the boosters were moving at mach 4+, and as they were angled to clear the tank they were angled away from each other. The aerodynamic forces would ...

13

Yes, the pressure of the first stage exhaust is always at least slightly subatmospheric, because that gives the maximum average ISP over the whole burn time. Rockets with boosters attached (parallel staging) often operate at the lowest possible exhaust pressure that prevents the flow from detaching from the nozzle walls. Historically, the Summerfield ...

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