# Tag Info

39

Fans work by moving cool air (or other fluid) over a warm surface. If there is no air, like in space, a fan will serve no purpose. Cooling things in space is actually a bit tricky because of this - objects on earth tend to lose most of their heat through conduction or convection, but in the vacuum of space, all you can do is radiate heat, which a fan will ...

30

Soviet planetary probes sometimes had pressurized compartments, so I suspected that they might contain fans. This answer confirms that Venera-8 had a fan. The illustration in the answer has the inner parts mislabeled, though. The fan is really #15 in the drawing. Reading through the source linked in that answer also confirms that Venera-5 had a similar ...

19

Imagine your telescope optics looked like this red-hot glass! Herschel's instruments look at the world in the wavelength range of 55–672 µm. When plotted as a function of wavelength, the thermal spectrum of a black body peaks $\approx 5 k_\mathrm B T$. The boiling point of liquid helium is 4.2 K. The peak wavelength for something at that temperature would ...

15

Sputnik-1 was filled with dry nitrogen pressurized to about 1.3 bar and had a fan to control gas temperature between 20° and 30° C. See Wikipedia in german or english. A picture of Sputnik-1 design with the cooling fan can be found here. Korabl-Sputnik 1, an unmanned early prototype of the later manned Vostok spacecraft, had a biological cabin with a ...

14

Could Stirling Engines work on sunlight alone? With the heated side facing the sun and the rest in its own shade, could two contra-rotating Vacuum Stirling Engines and flywheels, in tandem, accumulate torque, to power a reaction wheel? Yes. Can the heat from an ion engine be used to... power a Stirling engine? Yes! ...provide forward momentum this ...

13

Herschel was an infrared space telescope. According to this paper, the performance is expected to be not far from background-noise limited, with sensitivities (5σ in 1h) of ∼ 4 mJy or 3 − 20 × $10^{−18}$W/m$^2$, respectively. At most temperatures, the amount of heat radiated by the spacecraft itself would easily overwhelm the infrared signals it was ...

13

1) There is no superconducting magnet in AMS-2. This would have required cooling with liquid helium resulting in a limited life time of only 3 years because of helium evaporating. Instead, they used a normal, rare-earth magnet. It has a lower field strength and is heavier, but does not require any power or cooling. The cooling in AMS-2 is only for the ...

10

The effect of a fan in an electronic device is to accelerate the temperature exchange between circuits and atmosphere. But that temperature exchange works in both directions. When the atmosphere is even hotter than the electronics you expose to it, then improving the flow with a fan will make the part even hotter. That's the principle behind a convection ...

9

Nearly all Earth training was performed in the A6L model spacesuit (seen in the pictures above). Actual missions flew with the A7L model suit. Differences include: The outer (EVA) layer of the A6L had separate torso and pants, with entry at the waist. The EVA layer of the A7L was one piece, with entry at the back. Some astronauts were never expected to ...

8

To answer your first question: one of the main problems with using the oxidizer in general is oxidizing of the cooling channels. Any hot oxidizer has this problem, but oxygen definitively has this issue to the extreme, which is why earlier engines using the oxidizer as regenerative coolant have been with different oxidizers than oxygen (see for example the ...

6

Frank O'Brien in his book "The Apollo Guidance Computer: Architecture and Operation", on p. 229 concludes that effect from sublimator vapour thrusting could've been measurable: A quite real source [of unaccounted in state vector translation] arises with the exhaust from the LM sublimator, used to cool the vehicle's electronics. Although producing the ...

5

Unfortunately telemetry readings aren't shown on ISSLive.com (Tristan has actually pointed out to me there is no telemetry, which to me is a surprise, but there you go). See this analysis for the ISS. It is an analysis rather than a measurement and was performed in 1997 and so take it with a pinch of salt. Headline is -100 degF (-73°C) in eclipse to +150 ...

5

Supplementary answer to this excellent one because a) I like schematics, and b) downloaded a bunch of info a while back in anticipation of AMS EVA questions that haven't yet been asked. The cooling system: Explanation of the CO2 cooling cycle: From AMS02 TRACKER THERMAL CONTROL SYSTEM OVERVIEW AND SPIN-OFF FOR FUTURE SPACECRAFT COOLING SYSTEM DEVELOPMENTS

4

For an ablative nozzle one wants the right mix of properties: low thermal conduction, high strength, and a burn (regression) rate that produces enough gas to provide effective film cooling but not too high a burn rate so that you require a really thick liner to survive the burn time. Phenolic is well characterized by decades or research too, so it's well ...

3

The cross-section of the tubes increases from the front to the rear of the nozzle - they are "tapered". Reference, but no details - just mentions that they are tapered.

3

As pointed out, a cooling fan cannot reduce the temperature below the ambient. That doesn't mean it's completely useless in this case. First, OP said "Venus-bound." In this case a fan could be used to transfer heat from sunward sections to shadowed sections, or even better to radiating heat sinks on the shadowed side. Even when on the planet, it could be ...

3

Heat is exchanged via three mechanisms: convection (transfer of heat in gases and fluids) conduction (transfer of heat between touching solid objects) radiation (transfer of heat via thermal radiation) In the presence of an atmosphere, transfer via convection is usually the most efficient, followed by conduction. Radiation is -- by far -- the weakest form ...

3

The space shuttle's Orbital Maneuvering Engines (OMEs) were pressure-fed hypergolic engines burning nitrogen tetroxide and mono-methyl hydrazine. The combustion chamber was regeneratively cooled by hydrazine flow. The nozzle extension was radiation cooled. Source: Orbital Maneuvering System Training Manual

3

Regenerative cooling can be done with pressure-fed rockets just as it is with pump-fed rockets, the only differences are the source of the pressure driving the fuel (and sometimes oxidizer) through the cooling channels, and the lower pressures that are practical when the entire tank must be pressurized. Hypergolic engines can be either pressure-fed or pump-...

2

Pressure fed engines of PSLV's fourth stage (PS4) are hypergolic (MON/MMH) and their combustion chamber is regeneratively cooled with their Columbium alloy nozzle being cooled radiatively. They are modified versions of PSLV first stage (PS1) Roll Control Thrusters. Here is a good view of cooling channels machined on combustion chamber walls. Image sources: ...

2

An alternative to regenerative cooling is film cooling. Film cooling has been in use for small pressure fed thrusters for decades, not least on the Marquardt R4D used on the Apollo Service Module for attitude control - see the photo below. This was a 490N MMH/Mon engine that has also been used on countless other programmes. The principle has also been used ...

2

I think you are confusing cryogenic propellants and subcooled propellants. If they don't keep the propellants cryogenic, they will turn into a gas that would take around a thousand times as much pressure to fit in the same tanks. That would make the tanks unworkably heavy. Raptor and Starship are designed to use subcooled propellants, which are cooled below ...

2

I don't know of any RP-1/kerosene fueled engines that used two fluids for film cooling. The only instance of film cooling was of the gas generator exhaust fluid being fed into the nozzle to insulate it from the hot combustion products streaming out of the chamber. This btw was responsible for the F-1 exhaust gases always looking brighter in the center of the ...

2

For inhabited parts of the vehicle, water and water mixtures are preferred because leaks pose less of a threat to the crew. An even less threatening heat transfer media is air, which is commonly used to cool equipment in the cabin. For external cooling loops, ammonia and Freon have been used because of their superior heat transfer properties and lower ...

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