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That factoid, that the fuel pump on an F-1 was 55,000 horsepower, has stuck in my mind since the time I first read it. It's so mind-boggling. I would love to
by jcims 2y ago
That factoid, that the fuel pump on an F-1 was 55,000 horsepower, has stuck in my mind since the time I first read it. It's so mind-boggling. I would love to just experience the moment when the engineers on the program realized that this is what they needed to build and all they had was paper and pen and the will of a nation.
- foobarian 2y agoWhat really gets me is that SpaceX's Raptor engines have fuel pump power in that same neighborhood, and there are 33 of them on a Starship.
- matrix2003 2y agoWikipedia lists it as 37 MW, which does seem to be in the same ballpark (my amateur calculations put an F-16 around 44 MW). Not sure why people are downvoting you, but objectively the Raptor really is a marvel of engineering itself (maybe less than the F-1 that was created with slide rules at the time, but it does seem poised to upend space flight again).
- reportingsjr 2y agoA Raptor engine has about 1/3 to 1/4 of the thrust of an F-1 engine. However, the Raptor is far more efficient and much more impressive technically. They are really a marvel of modern engineering and science.
- JumpCrisscross 2y ago> Raptor engine has about 1/3 to 1/4 of the thrust of an F-1 engine Correct for Raptor 2. Raptor 3 is closer to half [1][2]. [1] https://en.m.wikipedia.org/wiki/SpaceX_Raptor https://en.m.wikipedia.org/wiki/SpaceX_Raptor [2] https://everydayastronaut.com/raptor-engine/ https://everydayastronaut.com/raptor-engine/
- RoddaWallPro 2y agoI have what is probably a dumb question: How can a Raptor turbopump need almost double the HP of a F1 while putting out 1/3 or 1/4th the thrust? (Assuming Elon's 100k HP number was correct, and/or hasn't changed). That just doesn't settle out for me. If it's got double the power, it should be moving double the fuel, so double the power, no?
- TaylorAlexander 2y agoMaybe something to do with pressure. Maybe it is higher chamber pressure and maybe higher pressure even with lower flow rates could require more power.
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- tliltocatl 2y agoRaptor has much higher chamber pressure (35 MPa vs 7 MPa of F1) and hence higher Isp (380 vs 304 in vacuum).
- jcims 2y ago35MPa is ~5000psi for anyone wondering lol.
- tliltocatl 2y agoAnd I took the effort to convert it to metric… Seriously, NASA uses the metric system and so should you.
- evo 2y agoPerhaps it has to do with the relative densities of RP-1 versus methane?
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- dotnet00 2y agoRaptor is also a lot smaller. F-1s were intentionally designed as large and high thrust because it'd have been simpler to build, test and control a handful of F-1s at the time, compared to say, 30 smaller but more efficient engines. The useful metric on this front would be thrust density, where Raptor 1 is a bit under twice that of F-1A, Raptor 2 is a little over twice of F-1A, and Raptor 3 should be ~2.5x of F-1A.
- capitainenemo 2y agoBut with more engines they can tolerate a failure or two (or even more) per launch. If a larger engine fails and you only have 3 of them, you're going to have a bad day. And, they do seem to test the heck out of their engines, even with 30 of them on a ship.
- sbradford26 2y agoYes those benefits can now be realized now with modern controls. Back when the Saturn V was designed the control systems necessary to manage 30 engines didn't really exist. Digital control was in it infancy and was only really implemented with a backup on the whole Apollo stack. Trying to manage that many engines while technically possible with controls of the era (check out the N1) means your control system would be introducing reliability issues instead of adding fault tolerance through redundancy.
- capitainenemo 2y agoDidn't the soviets give it a try? I'd swear they had a large number of engine design way back when also for fault tolerance. Ok, they didn't get it working but I'm pretty sure it wasn't due to lack of digital control... Surely they wouldn'tve even attempted it if it was impossible :) [edit] ah. That was the N1 you referred to. Ok. So you're saying it was possible, but it introduced more failure points.. So is that why it failed...
- dotnet00 2y ago
- hereme888 2y ago[flagged]
- indoordin0saur 2y agoThere are many brilliant people at SpaceX, not just the one. Your opinion of him (negative or positive) shouldn't affect the very clear assessment that what the SpaceX team has accomplished is amazing.
- JumpCrisscross 2y ago> have fuel pump power It’s slightly wilder. Raptor uses 100,000 hp per engine [1]. That is two F-1 scale turbo pumps per engine, i.e. 66 pumps altogether. All for the dress rehearsal. [1] https://x.com/elonmusk/status/1076618886932353024 https://x.com/elonmusk/status/1076618886932353024
- trhway 2y agoThe even more impressive here is the power/weight ratio - about 2000hp/kg (whole Buggati engine in 1 kg). (My speculative estimate - the Raptor turbine in the turbopump can hardly weight more than 500 kg as the whole engine is 1600kg -> whole turbopump less than 1000kg -> the driving turbine is half of it max). So anybody who plans to beat Musk/SpaceX (like i do when i finally get a real garage :) has a very high bar to clear. Additional facet is that Raptor turbopump is full flow and thus runs at very low (relative to other gas turbine machinery out there like for example F-16 at 1200C+) temps like 500-600C which means that the power can still be almost doubled with the same regular materials they use - steel and Inconel (and this is what we're seeing - about 1.5X power increase from Raptor 1 to Raptor 3 in a span of mere few years while the engine weight is even decreasing a bit)
- reddog 2y agoBut even MORE impressive is the current raptor engines cost between $1m to $2m each with a target cost of $500k when in full production. The F-1 cost an inflation adjusted $85m-$100m each. And the raptors are reusable.
- matrix2003 2y agoYep! I understand why people don’t like Musk, but SpaceX is doing some truly amazing work.
- avmich 2y ago> (like i do when i finally get a real garage :) Cool :) > Additional facet is that Raptor turbopump is full flow and thus runs at very low You write it further yourself, but rocket turbopump turbines aren't running with cold gas - the hotter the input gas, the more energy can be provided to pumps, so turbine blades have roughly the same requirements as those in F-16. The design on those blades is pretty complex, with materials, processes and substructures like internal cooling channels - all to reach possibly higher temperature to work with.
- spiritplumber 2y agoI had a chance to do some electronics work on an oceanic tug and at the time it blew my mind that the starter for its main engine was about the size of a semi truck's engine. They'd start that one electrically, let it warm up, then use it to start the big engine, then they'd switch it to being a generator for lights and radio and so on.
- paulkrush 2y agoSo this starter itself was a engine(ICE)?
- Dennip 2y agoDunno about OP, but old CAT bulldozers used to have smaller engines to start the main engine, before starter tech improved, iirc they were called "Pony engines(motors)"
- sethrin 2y agoWhich tug?
- spiritplumber 2y agoHeidi Brusco
- sethrin 2y agoNeat. I visited Valdez, Alaska lately and a friend was pointing out the tugs there. They seemed somewhat larger than other tugs I've seen. A data sheet says they have about 4x the horsepower of Heidi Brusco, coming from a pair of CAT C280-16 engines. I'm not clever enough to figure out how those are started. Cool boats are cool