Hot answers tagged

53

You are misreading the accident report. By 14:00:02, the vehicle had already begun to lose structural integrity, it had already begin to lose thermal integrity, and it had completely lost control authority. I'm going to digress a bit to distinguish between faults, errors, and failures. As a simple example, consider a bit in computer memory that permanently ...


32

The RCS wasn't depleted. The RCS firing was a symptom of a main issue, and it happened very late in the timeline, at 13:59:29. The RCS fired after the spacecraft's left yaw went beyond the capacity of the aerodynamic controls to compensate for it, Loss Of Control happened at 13:59:37, just 8 seconds later. The Loss of Control was due to a complete hydraulic ...


12

The Orbit Attitude and Maneuvering System (OAMS) was for orbit and was jettisoned before the retro burn, leaving the RCS for reentry. The com­plete OAMS had 16 small engines, which burned hypergolic propellants fed under pressure from one fuel (monomethylhydrazine) and one oxidizer (nitrogen tetroxide) tank. All engines were mounted in fixed positions and ...


11

The CM entered the atmosphere blunt-end first, which became the hottest part during re-entry (see picture below left). So you can't place RCS thrusters on that part of the CM, as they would melt; you can only place them on the sides of the cone, where it stays cooler. Thus, the CM had no aft-facing ($-X$) RCS thrusters. Note that the side of the CM toward ...


11

Actuator saturation is a control systems terminology. It means that the required (requested) control input exceeds the physical limitations of the actuators. For example once a valve is fully open you cannot ask for more fluid since it is fully open. But the cooling system might ask for more numerically from the valve due to some excessive heat (a ...


9

The concept and formula are correct for a coherent system of units. You have chosen to use US customary units and these are not a coherent system, i.e. in the situation in the OP one is bound to run into trouble. Looking on the bright side, your sense of what range the right answer could be in definitely helped you out here! There are several ways of looking ...


5

Puffin's answer is correct; this is just a supplemental that was a bit too involved for a comment. A physical interpretation of specific impulse measured in seconds is "the length of time for which one mass unit of propellant can provide the force needed to balance the mass against Earth gravity". Therefore 1 lbm of propellant with 73 sec Isp ...


5

sub-partial answer... Shuttle used a table lookup method to determine which jets to fire for a desired maneuver. If the full tables are available online, I am not aware of it, but there were some examples in training material. For background on the shuttle RCS and its operations please review the following answers first: https://space.stackexchange.com/a/...


4

RD-107 seems to have been used in the R7 missile. It says in the article for the missile that 1st stage: 4x jettisonable four-chamber RD-107 booster engines each with 2x vernier rocket engines plus 1x four-chamber RD-108 core engine with 4x vernier rocket engines. So the RD 107 stage was used in quadruplets. So vernier engines existed on diametrically ...


4

Assuming this simulation is correct, and I have no reason to doubt that it is, there is in fact true 6 degrees of freedom of movement possible. I do recall that at least one of the axis has less control, but I can't find the news report that states how the manual control felt according to the astronauts...


2

I know this question is old, but I randomly discovered a solution requiring only three thrusters on one thruster block that works if we don't mind introducing small transverse velocities. We need a thruster block that has is three thrusters at ninety degrees from each other all tangental to the satellite's surface, or in other words, a typical RCS quad with ...


1

Each thruster will have a thrust vector. That can be resolved into torque and translation depending on the CM. If you have six thrusters you should be able to get all six degrees of freedom. If you want one pure degree of freedom you have to solve a set of simultaneous equations, which is not hard. If there is a degeneracy in the system you may not be ...


1

Some form of electric drive might work if your spaceship had lots of power to spare (for instance if it had a nuclear reactor onboard or as part of the main engines). Something like VASIMIR or even just a miniaturised coilgun could possibly be made to work using electric and magnetic fields to accelerate plasma or small solid objects (think sand grains) to ...


Only top voted, non community-wiki answers of a minimum length are eligible