Similarly you could have a look at the original (ICBM) Atlas rocket. While it didn't jettison any booster rockets, it did jettison its two booster engines, which were fed from the core - as they didn't have their own tanks to begin with. The required engineering is very similar to doing crossfeed from a booster rocket towards the core engines.
Quote from: tp1024 on 02/21/2015 08:54 pmSimilarly you could have a look at the original (ICBM) Atlas rocket. While it didn't jettison any booster rockets, it did jettison its two booster engines, which were fed from the core - as they didn't have their own tanks to begin with. The required engineering is very similar to doing crossfeed from a booster rocket towards the core engines.This has be stated many times.
It can be done, just about any launch provider could do it if they wanted.
Quote from: Robotbeat on 02/22/2015 02:05 amIt can be done, just about any launch provider could do it if they wanted.How many providers have 3+ core liquid-fueled rockets to apply it to? There's Soyuz, Delta IV Heavy, and... uh...Edit: Just remembered liquid boosters are common in Chinese vehicles as well.
Since the pressure in the central tank is much higher, if the two side valves are one directional, once you open the center valve they will shut off automatically.Saves 4 actuators, but check valves can be tricky.
No. Cross-feed refers to engines being able to draw fuel from multiple sources. Shuttle's engines drew their fuel from a single tank.
Quote from: mheney on 02/22/2015 01:26 amNo. Cross-feed refers to engines being able to draw fuel from multiple sources. Shuttle's engines drew their fuel from a single tank.I thought the orbiters needed to fire their engines for the reentry burns, or am I mistaken? As there was no external tank present for that burn, surely the engines were connected to another source tank? Therefore they were basically crossfed.
Admittedly, it was a rather limited crossfeed.The gas generators of the Vinci engines used water to
Quote from: tp1024 on 02/21/2015 08:54 pmAdmittedly, it was a rather limited crossfeed.The gas generators of the Vinci engines used water to Nitpick:The earlier Arianes used Viking engines, not Vinci. The latter is a new and unflown cryo upper stage engine.I can't think of any rocket that's ever used propellant crossfeed in the manner the Falcon Heavy is planning to use. The earlier Atlas of course did have to have propellant cutoff valves to facilitate dropping the booster engine assembly, and that may be unique.--Damon
Admittedly, it was a rather limited crossfeed.The gas generators of the Vinci Viking engines used water to cool down the gas from the gas generator, instead of burning it with excess fuel to achieve this. The boosters of the 42L and 44L variants also used Vinci Viking engines, but didn't have water tanks. So they took the water from the core stage, cross feeding it into the booster engines. (A few tons of water in total, a bit less than 10% of the total fuel mass in the boosters.)Crossfeed has been used in 79 launches so far. Ok, it was in the other direction and only a fraction of the total amount that FH would use, but it was used on a regular basis.Similarly you could have a look at the original (ICBM) Atlas rocket. While it didn't jettison any booster rockets, it did jettison its two booster engines, which were fed from the core - as they didn't have their own tanks to begin with. The required engineering is very similar to doing crossfeed from a booster rocket towards the core engines.So, to put it that way: What is all the fuss about? (At least in terms of the basic mode of crossfeed - feeding a few of the engines from the outer booster tanks.)
Quote from: tp1024 on 02/21/2015 08:54 pmAdmittedly, it was a rather limited crossfeed.The gas generators of the Vinci Viking engines used water to cool down the gas from the gas generator, instead of burning it with excess fuel to achieve this. The boosters of the 42L and 44L variants also used Vinci Viking engines, but didn't have water tanks. So they took the water from the core stage, cross feeding it into the booster engines. (A few tons of water in total, a bit less than 10% of the total fuel mass in the boosters.)Crossfeed has been used in 79 launches so far. Ok, it was in the other direction and only a fraction of the total amount that FH would use, but it was used on a regular basis.Similarly you could have a look at the original (ICBM) Atlas rocket. While it didn't jettison any booster rockets, it did jettison its two booster engines, which were fed from the core - as they didn't have their own tanks to begin with. The required engineering is very similar to doing crossfeed from a booster rocket towards the core engines.So, to put it that way: What is all the fuss about? (At least in terms of the basic mode of crossfeed - feeding a few of the engines from the outer booster tanks.)This is not cross-feed. This is the exact OPPOSITE of cross-feeding, meaning that the heavy tanks had to be lifted for LONGER than the engines using the liquids in them, while in normal cross-feed, some of the tankage needs to be lifted for LESS than some of the engines using them.
