15

This is especially interesting considering that the Service Module and LM RCS used the same thruster hardware (Marquardt R-4D). The R-4D was originally designed for MMH and first flew on Lunar Orbiter 1: Marquardt experimented with a variety of liquid storable propellants. They selected NTO and MMH for their thrusters. However, government requirements led ...


10

There will likely be significant differences in the required tankage, if nothing else. The paper Lunar Lander Conceptual Design shows a comparison between landers with similar payload requirements and different engine systems. Note the different in tankage and propellant weights for the two options.


8

Generally, well-designed pressure-fed hypergolic engines are very reliable. However, failures of some designs have certainly occurred. Here are some recent examples: The Juno probe, currently in orbit around Jupiter, had to significantly change its mission plans due to concerns about potential catastrophic (as in explosive) failures due to stuck helium ...


7

A lander with storable propellants needs to keep them at close to room temperature, for a minimum of several days. A hydrolox system will take up much more volume due to the low density of LH2, and that big LH2 tank has to be kept at around 20 K. You are going to need a major structural redesign just to deal with the greater volume of the liquid hydrogen ...


7

Until Masten Space Systems reveals the exact composition of the propellants, we can only speculate on the combinations they used. Based on what you have presented in question we can rule out options one by one, but we cannot be 100% sure especially for fuels because if we miss oxidizer than we will miss fuel to. The smoking gun here is a sentence “prepared ...


6

To draw out a quote: Symmetrical dimethyl hydrazine turned out to be a dog (it's [sic] freezing point was only--8.9 [degrees]) Not only have I found a rare typo in the remarkable Ignition! (and in the second edition, to boot!), but there you go: SDMH was a good propellant, but it froze far too readily. To answer your question: yes, it was probably a ...


6

Our company (Malin Space Science Systems) is collaborating with Stellar Explorations to develop a very small biprop propulsion system for cubesat missions. There is a definite lack of options in this size range, mostly because cubesats have been prohibited from having significant propulsion systems by launch providers or primary launch customer rules up ...


5

Yes it is possible to construct a hypergolic solid-liquid rocket propellants. Case in point a metal organic framework of imidazole derivatives with Zinc, Cadmium or Cobalt metals as the solid phase and concentrated nitric acid as the liquid oxidizer. Paper https://chemrxiv.org/articles/Hypergolic_Zeolitic_Imidazolate_Frameworks_ZIFs_as_Next-...


4

This website suggests SDMH is incompatible with oxidizing agents, water. So it can be used for hypergolic purpose.This quote is from Sittig's Handbook of Toxic and Hazardous Chemicals and Carcinogens: Properties of SDMH Forms explosive mixture with air. A strong reducing agent and strong base. Violent reaction with strong oxidizers, strong acids, metallic ...


3

The ISS can be refueled with UDMH and N2O4 by visiting vehicles, initially the ATV: http://www.esa.int/Science_Exploration/Human_and_Robotic_Exploration/ATV/Premiere_for_Europe_Jules_Verne_refuels_the_ISS The propellant transfer is done through the docking connector, through pipes that run outside the pressurized portions of the ISS.


3

It's worth remembering a lot of the research John D. Clarke recalls in Ignition! was not primarily being conducted with the requirements of civilian space flight in mind. The military were interested in propellants that would allow munitions to be fuelled in the factory, then stored indefinitely, but ready for immediate use. Setting aside any risk of ...


3

Well, after useful comments and some research I can summarise: The chemical reaction of bipropellant hypergolic fuel is more complex: 1) There are more products of the reaction 2) Some part of the fuel remains unburned In this link by @Uwe is stated that exhaust plume contains microdroplets of unburned propellant, with size up to several micrometers. ...


3

Apart from the mechanical aspects of tankage, ullage, ignition, and the like, there's a significant safety issue. Unless you're starting a Moon colony, the "and return them safely to Earth" bit is pretty important. Hypergolic engines can be made extremely simple and reliable -- the Apollo LM ascent engine was basically a pair of valves, a combustion ...


2

I did find on Astronautix several examples of pressure fed kerosene-LOX engines, some of them built, others "notional": AABS Liberty KSR-3 P4-1 RS-36 PF RP-1 Sea Dragon-1 Microcosm 22N As well as some gas generator hypergolics, mostly Russian vernier thrusters: 8D423/11D423 (UR-100) RD-0207 (UR-200 vernier) RD-0230/RD-0257 (SS-18 vernier) RD-0236/RD-0251 (...


1

As far as I know the answer is no. The autoignition temperature of Hydrogen is 536 °C according to Wikipedia. Although this temperature could vary with pressure, I am also unaware of LOX/LH2 being hypergolic, hence adding water to the mixture (you asked about hydrogen peroxide) should not make things that much easier.


1

The bright particles you see flying from the Souyz nozzle are the pieces of the "nozzle cowling". It is kinda ceramic material coating of the nozzle. The amount of coating is calclulated for the nozzle operation. It wears off gradually during the nozzle serving time.


1

The decision to use different fuels for the main engine and the RCS was made before contractors were assigned, back when various NASA centers were conducting feasibility studies. At the time, the mission mode was expected to be a direct descent to the moon in one spacecraft. The main propulsion was expected to be solid rocket motors! 4.4.7.1 Service ...


1

My advice is to synthesize some Chromyl Chloride from a oxidized salt of Chromium as it is hypergolic with methanol and sulfur. You can also get about a liter of the liquid with just a days work and it isn’t too toxic to handle. Sadly I couldn’t find a reliable propellant mix using n2o.


1

This is a mix that apparently could work. "When passed over a warm ruthenium catalyst bed, gaseous nitrous oxide and an ethylene-ethane gaseous blend combust instantly" Supplies could be found for the following:Ruthenium and Ethane But I could not find sources for Ethylene, but it seems to be available for industrial uses. This could disqualify this ...


1

Yamal 601 launched this year looks as if it may be a candidate. Its not clear from the references though some sources seem to have a reason to claim there was a problem with the main 400N thruster as it transferred to complete is GTO transfer on 10N engines. Sources: Gunters "During orbit raising to geostationary orbit, a possible irregularity occured ...


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