# Tag Info

34

Off the top of my head I can think of several failures caused by miscabling. On Apollo 6 the signal to shutdown a malfunctioning second stage engine was cabled to a different engine, resulting in two shutting down instead of one. See: Apollo 6, reason for premature engine shutdown of two engines of second stage of Saturn V? The system used to release a ...

25

Not in flight but this 1996 NASA lesson learned document lists multiple instances of mis connected cables during ground assembly and test including on Galileo. It in turn references JPL documents attempting to avoid re-occurrence, unclear if ESA has a similar document/process. The concept here is keyed connectors, many mil spec connectors come in multiple ...

12

Not flight related, but everyday: Flammable gas cylinders have left hand threads. Oxygen, and other oxidizing gasses have right hand threads. The two examples I can think of involve propane and acetylene tanks. (I think that small propane cylinders now have a unique right handed thread for connecting to barbecues) On a different tack: Firehose couplings ...

9

HTP will sustain a combustion reaction without a catalyst once ignited, but it's not clear to me if the reaction proceeds quickly and smoothly enough to be a good idea for rocket combustion chambers. As MSalters comments above, hydrogen peroxide "will undergo potentially explosive thermal decomposition" before reaching its theoretical boiling point,...

8

This is literally where Murphy's Law, "Anything that can go wrong will go wrong", came from. If you design a parts so they can be fitted incorrectly, they will be fitted incorrectly. "Murphy" is Edward Murphy Jr.. He was an aerospace engineer working on rocket sleds. In 1948 he suggested installing strain gauges to measure the force of ...

7

It is better to use keyed or polarized cable connectors that could not be inserted to a wrong socket or in a wrong rotation. But what should be done with the second stage of the Saturn V used for Apollo 6? When a fuel line ruptured, two instead of one of the five engines were shutdown because some cables were switched between two engines. So the connectors ...

7

First time answering here, so let me know if I need more detail. I worked as an engineer in the avionics testing lab for Space Shuttle for about 5 years, and I have personally witnessed incorrect cables connected multiple times, sometimes resulting in permanently damaged equipment. It's actually not that difficult to mix up your cabling. With most of the ...

6

Do not have the maths skills to generate an example rocket engine turbine/pump system from first principles but the Wikipedia page indicates that efficient operation both as a pump and a turbine requires the plates to be close enough together to achieve laminar flow and that the fluid path make several circuits around the disks (to maintain laminar rather ...

5

According to the JAXA page about the rocket, it's a solid-fuel motor: The propellant, a pre-formed grain, polyurethane composite with a low burning rate... By polyurethane composite I assume they mean HTBP plus ammonium perchlorate and aluminum powder, since that's what JAXA generally uses for solid rockets. Since it's a solid rocket stage, the motor ...

5

Your question is very general, so a general answer is that, a valve or valves control the flow of propellants to the turbine that drives the pump. An engine controller determines the proper valve setting based on sensor readings from the engine. For the case of the Space Shuttle Main Engine During the engine run phase, the MOV, MFV, and CCV are switched to ...

4

A "throat plug" is a cover to prevent contamination from entering the engine's combustion chamber from the direction of the nozzle. It can also serve as a "stopper" for leak testing. I could not find a picture of an F-1 throat plug, but here are some diagrams of the Space Shuttle Main Engine's throat plugs. This diagram shows the upper ...

4

Partial answer. At least not for a main engine for an orbital rocket, as the Rutherford engine is currently the only such engine using an electric pump. And it uses batteries. However, conclusively ruling out all smaller secondary thrusters and propulsion systems is much harder. Electric feed pumps are beneficial for reducing complexity by not having to ...

3

In contrast to Tristan's answer, which claims that propyne performance is “probably” worse than saturated hydrocarbons currently used due to higher average mass of combustion gasses, propyne (methylacetylene) is actually superior in terms of Isp and according to this source is 4th performing fuel among all hydrocarbons, while propadiene (allene) being 2nd. ...

3

In more conventional civillian design, otherwise identical parts are often made hot swappable and truly identical, it just means less things to keep track of. Cables and connectors are, in my experience with non-critical systems, highly likely failure points, just like anything else that moves. When aerospace people talk about the certainty and reliability ...

2

I think two-wire reversals are not uncommon, likely to be found from time to time with very minor consequences, e.g. two heaters are swapped with respect to their command codes. However, as everyone loves a photo here is a bigger event: 2013 Proton failure and a little explanation: The statement appears to confirm earlier Russian press reports that ...

2

Another solution: Instead of physically keying cables, include an extra wire in the cables that is used to communicate with a tiny bit of electronics that simply outputs an ID code. That lets the device on the other end query what it's connected to and report back if it's wrong. Once confirmed during basic electrical systems checkout after assembly, there ...

1

OKEANOS was a JAXA project of circa 2010, combining a solar sail and an ion engine. Authors were going to send it to Jupiter's trojan asteroids with a possible sample-return trip to Earth. The sail would have been made of a 10 μm-thick polyimide film measuring 40 × 40 meters (1,600 $m^2$) covered with 30,000 solar panels 25 μm thick, capable of generating ...

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