# Tag Info

40

As Organic Marble hints, there is about 140 degrees Celsius between kerosene's freezing point and oxygen's boiling point; there's no temperature at which both are liquid. Even if the propellants were more thermally compatible, putting your fuel and oxidizer in the same tank is a really dangerous idea. Typically, propellant tanks are pressurized with helium ...

35

The Space Shuttle used liquid hydrogen, contained in the external tank along with liquid oxygen. While the Falcon rockets do use liquid oxygen, they do not use liquid hydrogen. Keeping the liquid hydrogen cool was the primary driver for the foam. The Orbiter was mounted alongside and below the the top of the external tank. The Falcon payload is mounted at ...

31

Most commercial commodity specifications for hydrocarbons such as gasoline, kerosene, Diesel fuel, jet fuel, naptha, mineral spirits, etc are fairly broad. RP-1 is kerosene that meets some particular specifications that are important for use as a rocket fuel, but not so important for burning it in gas turbines or diesel engines. The specifications for RP-1 ...

26

Possible: yes. Feasable: not really (at least not for power applications). The main trick is energy density (per volume) - gases tend to be quite significantly less dense than liquids - and thus the tanks would need to be much larger and heavier - so they are commonly used in their condensed liquid form. For small engines gases have been used - both as ...

22

Because it will almost certainly go KABOOM. Intimately mixed fuels and oxidizers are pretty much indistinguishable from explosives, and in particular, LOX intimately mixed with flammable hydrocarbons is wildly dangerous -- rather than being something you can handle, it tends to be set off by shock, vibration, or adiabatic compression that can be caused by ...

20

The US National Institute of Standards and Technology (NIST) is pretty useful for that. They offer a free tool that allows you to calculate a lot of useful properties of multiple interesting compounds including e.g. oxygen, nitrogen, helium, hydrogen, methane and propane: https://webbook.nist.gov/chemistry/fluid/ E.g. we can plot the density of Oxygen at 0....

18

The problem is not the foam breaking off per se, but the fact that the orbiter was below the fuel tank and got hit by the falling foam. The Dragon capsule is on top of the stack, it can't be hit by a piece of foam that comes off the booster.

15

Yes, and it is currently being done on a few engines, notably SpaceX's Raptor engines. They run on liquid oxygen and liquid methane. These are run through turbopumps in two different mixture ratios, burning a small part of the fuel which spins the pumps and vaporizes the rest of the fuel. When they enter the combustion chamber they are both in gaseous form. ...

13

As described in this QA, the upper stages of the Saturn V could fire their J-2 engines at different mixture ratios. The second stage would switch from 5.5:1 (oxidizer mass to fuel mass) for higher thrust, to 4.5:1 for higher fuel efficiency partway through the ascent. The third stage would normally start at 4.5:1 and switch to 5:1 partway through the burn,...

13

The hard part is that $P_e$ isn't a completely independent variable. As the gas expands past the throat, thermal energy is being converted into kinetic energy. The gas cools down and speeds up. So if you shorten the nozzle (creating an underexpanded flow), there is greater pressure at the exit (good). But the exhaust speed $v_e$ is lower (bad). The \... 12 Do all chemically-fueled rockets need foam insulation? Not all, but some do. Generally the small subset of ones that utilize hydrogen fuel. The hydrogen-fueled Delta IV uses essentially the same insulating foam as shuttle did. Photo from clickorlando.com The hydrogen-fueled SLS uses a similar foam. Photo credit NASA This question Insulation on rockets--... 11 The 1976 NASA monograph Liquid Rocket Disconnects, Couplings, Fittings, Fixed Joints, and Seals defines "couplings" as Couplings are manually actuated separable connectors that require more than a few seconds for engagement or disengagement. and lists the following types: Flanged Threaded: Dynamic swivel couplings Shape memory alloy is not ... 8 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 ... 7 According to this nasaspaceflight.com forum post, the dynamic viscosity of Falcon 9 chilled RP-1 is about 3.3 cP. The table here lists the viscosities of some maybe-not-so-everyday fluids; Falcon fuel is kept twice as viscous as ordinary kerosene at room temperature (1.64 cP), comparable to milk or blood. Water at room temperature is 0.89 cP. I tried to ... 6 At low temperatures, the activation energy for pure CH4 O2 oxidization is about 170kj/mole. (See figure 1 here) That’s about 1.8eV per atomic reaction. 1.8eV can be provided by 688nm red light, or any shorter wavelength. So generally, visible light can initiate reactions. I can’t quantify how many photons/cm2 it’ll take to start a runaway reaction from ... 6 To complement the answer: 1 L contains 1141 g of liquid oxygen 1 L contains 1 g of gaseous oxygen (at 1ATM) Of course you can compress it but the container will add more weight (highly undesirable). But that's not over! Rockets consume not only a lot of propellant, but they consume it fast. A Saturn V consumes 18000 kg every second. That would be ... 6 RP 1 fuel was red dyed for a thermal stability experiment on JP-8 and RP-1 fuel of various ratios. High Reynolds Number Thermal Stability (HiReTS) testing device. There are several factors that set the HiReTS machine apart from other thermal stability tests. The red dye of RP-1 was used to detect the various effects of parameters like temperature and ... 6 National Geographic reports that the 2014 Antares explosion carrying a Cygnus v4 for the Cygnus CRS Orb-3 mission "knocked two spectators off the bed of their pickup truck and another off her dock. The blast broke windows and imploded doors in buildings close to the launch site", which both shows that something did indeed knocked over and windows got blown ... 6 We have the capability to launch this already, so it is feasible, just very expensive when there are better alternatives. A spacecraft as you describe isn't just 50 tons of solar panels, you need a huge structure to hold them on, huge amounts of maneuvering fuel to align the spacecraft, extremely powerful gyros, and other elements that would have to be super-... 5 Nitrogen Dioxide is a chemical that forms an equilibrium with Dinitrogen Tetroxide, which in the world of rocketry is often just called "Nitrogen Tetroxide" so as to increase the amount of confusion. If you have a tank of one, it will change between being one or the other based on temperature or pressure. This is one of the commonly used hypergolic storable ... 4 I performed a feasibility study for a Soyuz launch site on Christmas Island many years ago in support of the Asian Pacific Space Center. One of their press releases talking about the project is here: https://www.aerospace-technology.com/projects/christmas/ As part of that investigation I discussed the feasibility of adding enough refrigeration capacity to ... 4 The book Burt Rutan's Race to Space by Dan Linehan describes why the predecessor of Spaceship Two chose a hybrid engine. Rutan ruled out solid motors because they cannot easily be shut off (a safety concern). He ruled out liquid motors because of cost and complexity. Rutan settled on a hybrid engine as the best compromise between safety and cost. Also ... 3 During the moon race, a soviet N-1 rocket exploded seconds after liftoff. This is ranked as one of the largest conventional explosions with an approximate yield of 1 kt of TNT. Upon impact of the base of the N1 with the pad, the vehicle exploded, destroying launch pad 110 east, which would take over 18 months to repair. [...] At T+23 seconds ... 3 PS to previous comment about refrigeration in the X-15. It had none, keeping weight absolutely minimal precluded it. Temperature was far more of an issue for the LOX than for the NH3. During captive carry to launch the LOX was replenished from a supply in the B-52 carrier aircraft; otherwise some degree of boil-off occurred. A special case of venting LOX was ... 3 The history of rocket fuel development has been dominated by getting them to work at the range of temperatures we want. For instance finding a fuel that is liquid enough to work in the Arctic, and not so volatile that it can't be stored at reasonable pressure in the desert. Unfortunately, kerosene freezes well above the boiling point of oxygen. It might be ... 3 to put it in 3 words "it will explode." you see fuel burns with oxidiser and mixing the two in the same storage will well let me make it in steps: you ignite the engine... the flame flows into the tank... that burns too... in a closed space... rapidly... which causes the tank to burst... and then you have no more rocket. ): 3 The critical pressure ratio for a de Laval nozzle is $$\left(\frac{P_0}{P_{atm}}\right)_{crit} = \left(\frac{\gamma+1}{2}\right)^{{\gamma}/({\gamma-1})}$$ WhereP_0$= stagnation pressure in chamber$P_{atm}$= atmospheric (back) pressure$\gamma$= ratio of specific heats for the gas$(P_0 / P_{atm})\$ must exceed this critical value in order for a de ...

2

tl;dr: I see that comments below the question by the OP argue against this being a deal-breaker problem but I'm going to point it out anyway as a partial answer. Any engine using "sand" as a reaction mass will have to avoid any significant production of silica nanoparticles so large that they are not accelerated in the nozzle. Assuming a perfect, ...

2

Yes! There are various studies conducted on the viability of fatty acids / parrafins / biodiesels as rocket fuels. Bio rocket fuel is an actual thing! This study shows that virtually any lipid-based feedstock, or raw material with a fat source -- including what is perceived as low-quality feedstock like cooking grease -- and turn it into virtually any ...

2

First, clustering of engines saves a lot of engineering work. You only design one engine, rather than more than one. This is especially valuable in the extremely conservative world of man-rated aerospace. It boils down to modularity. Second, if you're cost-sensitive, and you're trying to mass produce a ship, clustering lets you mass-produce engines. For ...

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