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Are there any examples of pressure fed engines used on launch vehicles? I already know of the ones on the wikipedia page which include

  • Firefly Space Systems
  • OTRAG (rocket)
  • Quad (rocket) of Armadillo Aerospace
  • XCOR EZ-Rocket of XCOR Aerospace
  • Masten Space Systems
  • Aquarius Launch Vehicle
  • NASA Project Morpheus prototype lander
  • NASA Mighty Eagle mini lunar lander
  • CONAE Tronador II upper stage
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  • $\begingroup$ This is an example of a list question that I don't forsee being all that useful. What use is there to have this list here instead of just asking in chat? $\endgroup$ – called2voyage Sep 22 '16 at 17:31
  • $\begingroup$ Well the list will certainly be useful to me! I have not seen any restrictions about asking list questions. $\endgroup$ – SpacePaulZ Sep 22 '16 at 18:04
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    $\begingroup$ See here. Unfortunately, in practice it is a little more complex than simply saying all list questions are off topic. There is an existing Space Exploration Meta question on the topic. Perhaps if you could quantify exactly how the list would be useful, that might help. Note: I haven't voted or closed yet, but I'm cautioning you that your question might not be well received in its current form. $\endgroup$ – called2voyage Sep 22 '16 at 19:13
  • $\begingroup$ Note: if the utility of your list question is mere curiosity, then there may not be sufficient motive for people to maintain the list going forward--which would make a poor Stack Exchange question, but a great thing to ask about in chat. $\endgroup$ – called2voyage Sep 22 '16 at 19:16
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    $\begingroup$ The Wikipedia article seems to be a pretty comprehensive list. The question lists about half of the ones from the article, and the less interesting half at that, being the ones that never went beyond the drawing board. $\endgroup$ – Hobbes Sep 22 '16 at 19:26
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Here are some pressure-fed engines that have been flown:

  • The Diamant used a first stage (Emeraude) with 1 Vexin engine. It was used in 12 launches, including the one that put the first French satellite (Astérix) into orbit.
  • On the ELDO Europa I rocket, the second stage (Coralie) used 4 Vexin engines. The 11 Europa launches all failed.
  • The Apollo LEM ascent engine and descent engine were pressure-fed too. They used Helium tanks as their pressure source.

The Emeraude and Coralie were inefficient stages due to their heavy tanks. Also, the pressure in the tanks was created by a gas generator, so instead of having a stage without gas generator they just split up the engine (the GG was installed at the top of the stage).

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  • $\begingroup$ please correct "theeir" spelling. By the way, Isn't the descent engines of Lunar module pressure fed? $\endgroup$ – Amar Nov 24 '18 at 12:08
  • $\begingroup$ Not only the Apollo LM ascent and descent engines, but also the SM engine. $\endgroup$ – Uwe Nov 24 '18 at 18:10
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Reaching orbit with a pressure fed engine is really tough because of the need of high thrust and to achieve high thrust, high combustion chamber pressure is needed. And hence the pressure, at which propellants are stored, have to be very high leading to very high mass of the propellant tanks.

Because of the above reason pump fed engines are being used till date (23/11/2018) which reduces mass and require less propellants to reach the orbit compared to pressure fed engines.

For small thrust requirement (like thrust vector control, orbit change, etc.), pressure fed engines are the best option because it reduces complexities in making pumps & turbines system and are quite compact in size.Now companies are coming up with pressure fed engine but just for the last stage where they have to do minute corrections in trajectories.

Armadillo, Masten, XCOR, etc. are companies who have made landers and are low in mass and hence require less thrust. Because of which they are able to use pressure fed engine. And most importantly these landers are designed for the moon where gravity is less and requires lesser thrust to lift-off the same mass than the earth.

In recent times, a lot of new student space programs are coming forward, like SDSU, dareTuDelft, USCLPL, etc. (get to know more on this website), who are using liquid propellants and pressure fed engine system.

Finally, by the increase in material research, to find better material in strength to weight ratio, making a launch vehicle with just pressure fed engine system is not impossible in near future.

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    $\begingroup$ "high combustion chamber is needed"? Pressure in combustion should chamber should be high and pressure in tanks for pressure feed should be even higher. But a large volume tank for high pressure would be very heavy. $\endgroup$ – Uwe Nov 23 '18 at 17:38
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    $\begingroup$ @Uwe, thanks for noticing. I missed it completely. Just edited :D $\endgroup$ – Amar Nov 23 '18 at 17:45

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