Podcast #128: We chat with Kent C Dodds about why he loves React and discuss what life was like in the dark days before Git. Listen now.
38

Ice. All these rockets use oxygen as the oxidizer component of their propellant. The Saturn 5 also used hydrogen in some of its engines (upper stages). They are stored in liquid state, which requires very low temperatures (below -183c for oxygen, below -253c for hydrogen). Despite insulation, some of the outside surfaces can get cold enough to condense and ...


30

You are missing how heat is distributed in exhaust. Most of propellant ejected through the nozzle never makes contact with the nozzle surface or walls of the combustion chamber, and as result never has any chance to transfer its heat into them. The exhaust gas primarily cools through adiabatic expansion - high pressure and high temperature both transformed ...


24

The fuel used in the shuttle's Orbital Maneuvering System engines and used for the deorbit burn was not cryogenic; it was storable hypergolic fuel. The cryogenic hydrogen and oxygen fuel burned by the main engines was used only during the ascent, which took only about 10 minutes.


20

While in the atmosphere, a forward center of gravity contributes to stability. You want the center of gravity to be forward of the center of pressure for aerodynamic stability. A longer distance between the center of gravity and the gimbaling engines gives them more control authority as well.


19

As suggested by OrganicMarble in a comment, nitrogen is miscible with oxygen (you can thus make liquid air). According to NASA Technical Paper 2464, this is a major concern because using "enriched air" instead of pure oxygen as the oxidizer degrades the performance of the engine: The transfer of liquid oxygen (LOX) from a storage vessel to a rocket engine ...


16

Kennedy Space centre in Florida formerly had its own plant for the manufacture of cryogenic fuels and other liquids. This is now closed as noted earlier. The procurement for cryogenic fuel for NASA is done via the office of procurement at KSC. It was determined that the US has only one supplier cryogenics that can supply the cape with the necessary 30 trucks ...


16

I wouldn't recommend it, and there's several reasons why. First, even if we assumed you'd get chemically pure water out of the exhaust plume, in essence distilled water, it would lack any dissolved minerals and cause you to lose electrolytes. If that was all that was wrong with it, then small quantities wouldn't hurt you, but you'd have to substitute lost ...


15

Confusion abounds. Spaceflight 101 has this to say about the NK-33: The NK-33 requires sub-cooled Oxygen with a temperature below its boiling point of -183 degrees Celsius to cool the turbopump bearings that would otherwise fail. Also, sub-cooled LOX has a higher density, close to that of Kerosene, reducing required tank volume and overall launch vehicle ...


14

NASA has done an extensive report on this, and in fact, cryogenic hydrogen tanks are considered to be one of the greatest technical achievements that NASA managed. Much of this is specific to the Centaur upper stage, but here's a few interesting quotes from the article: Page 38 Bossart led Mrazek out into the factory yard, where a Centaur tank stood ...


13

...is the tank within a tank a sound engineering concept for rocket stages? I take this to mean that you are not talking about pressurant bottles or other small devices submerged in the propellant tanks. Instead you mean the large primary propellant tanks. Then, No, this is not a good idea. It doesn't need to be a double-walled, or "dewar-flask" tank....


11

The SSME is a staged-combustion rocket engine, which means that some small fraction of the propellant flow into the main combustion chamber is first diverted into a small pre-burner (two actually). These preburners combust (relatively) small amounts of fuel and oxidizer to produce hot exhaust gas which is expanded through a turbine, which is mechanically ...


10

This is complicated, but here is the gist: Thrust is generated by flowing high pressure gas into a lower pressure environment. This flow is supersonic, so what goes on downstream of the throat (top of the the nozzle) cannot be sensed by what is going on in the combustion chamber (sound is just a pressure wave). The nozzle is supersonic, the combustion ...


10

The biggest risk I foresee is nitric acid. A hot open flame in the atmosphere will cause N2 and O2 to react, creating a number of different molecules such as NO and NO2. These dissolve reasonably well in water and will form acids.


10

Ariane 5 does not shed ice at liftoff. The first stage is covered in foam insulation that prevents ice buildup. In this image, the insulation is the brown stuff. Later Ariane 5 versions switched to light-blue insulation tiles. The Shuttle had insulation on its External Tank for the same purpose. For the Shuttle, it was critical not to have chunks of ice ...


10

This is a really good question and the answer is probably not 100% known, even by SpaceX at this moment. No doubt they will have some active cooling to minimize boil off. Structurally there are tricks they can play. For example the landing fuel is stored in a smaller tank, which is submerged in the main tank. Thus the surface area to warm up over is ...


9

For the Apollo 11 launch, at S-IC ignition the frost weights were: S-IC: 1400 lb/635 kg S-II: 450 lb/204 kg S-IVB: 300 lb/136 kg But by holddown arm release: S-IC: 650 lb/295 kg S-II: 450 lb/204 kg S-IVB: 200 lb/91 kg So about half the ice was shed (due to vibrations) before the stack left the ground. The Saturn V Skylab flight evaluation report has ...


9

The existing answers do not accurately describe the procedure for the Space Shuttle system (or, I believe, for Apollo, but I am not 100% sure of that - see note at end of answer). The propellant tanks in the Space Shuttle's External Tank (ET) were never filled with nitrogen. The initial condition for LH2 loading into the ET LH2 tank was with the tank and ...


9

At Kourou, there's a production plant for liquid hydrogen and oxygen. The plant is run by Air Liquide, a French company that specializes in industrial gases. There's also a casting facility for solid rocket stages.


9

The melting point of hydrogen isn't much lower than its boiling point (6K), so the temperature isn't necessarily that much of an obstacle. However, using solid fuel requires either melting it, or burning it in place. Trying to burn solid hydrogen would likely result in the whole thing flash-boiling from the radiated heat, so that's a bit of a non-starter. ...


8

An additional reason that the forward position is advantageous for the LOX tank is the pressure head created by the distance from the tank to the engines. The turbopumps that drive the engines need sufficient inlet pressure to prevent cavitation. Moving the LOX tank forward allows the weight of the LOX to contribute to that pressure, which reduces the ...


8

Different stages use different means; Centaur uses(used) a thermodynamic vent mixer system for its LH2 tank. This device served to keep the bulk propellant well mixed, and ensured that only gas was vented.


8

It was filled through the "T-0 umbilicals" (referring to the time of disconnect). LO2 through an umbilical on the Orbiter boattail, LH2 through one in the midbody. This schematic shows the plumbing from the umbilicals to the Centaur through the CISS (Centaur Integrated Support System). Source


7

Short answer, they let some boil to keep the rest cool and also 'waste' some to cool the plumbing and tanks before loading. The bulk cryogenics are made by compression, not cooling and from that point on normally the liquid is kept liquid by evaporation during shipping and storage. This can become a complex engineering problem for large rockets to handle ...


7

Unsurprisingly, it worked exactly like it did in shuttle. To assure uniform flow, the capillary restrictors are coiled around a warm water-glycol line to increase the oxygen temperature. Page 2.7-3 The aforementioned oxygen supply capillary restrictors are wound around the line routed to the space radiators and relief valves. The other line is ...


6

The closest I could find to information on this came from this brochure: Design Improvements in GSLV-D5 Based on its performance during the earlier missions, end-to-end design of GSLV as well as indigenous cryogenic stage systems have been re-examined. Design modifications are implemented wherever required along with rigorous ground testing and ...


6

ISRO's indigenous CUS (Cryogenic Upper Stage) does have restart capability, but this wasn't tested as it wasn't a requirement of the GSLV-D5 flight profile (PDF), so I can't comment on its reliability. ISRO did test variable thrust though, which is half-way there already. A full restart would require MECO (Main Engine Cut-Off), completely cutting supply of ...


6

Depends on the fuel. With Liquid Oxygen, for regular launches, it makes more sense to build a LOX plant nearby and pipe it to the pad/storage tank, than it is to buy it offsite. You can see the SpaceX oxygen ball near the pad at LC-40. It seems that during the Saturn project they had such a plant at the Cape near LC-17 but no longer. Nitrogen in large ...


6

Typically they drain the cryogenics back, if they can. Now it depends on the cryogenic. Oxygen can be drained and reused. Hydrogen in liquid form is very hard to keep cool enough, and they will drain it, but they will lose lots of it to venting. Liquid Nitrogen that they use for pressurization they may just let vent, since the quantities are pretty ...


5

The best I can find on this is a presentation from 2011 about the (discontinued) Altair Lunar Lander's needs, written in conjuction with the Department of Energy, in which the state of the art about cryogenics was discussed. This specifically focuses on Hydrogen, the most challenging cryogenic used in space flight. During the "Power Reactant Storage Hydrogen ...


5

The objective of cryofreezing is to slow or stop the body’s metabolism. Essentially, put you to sleep for a very long time without aging and thaw you out when you get to where you’re going. While it sounds whacky it’s actually closer to reality than it sounds. Slowing of the metabolic rate happens naturally in many animals during hibernation, and there is ...


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