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9 hours ago, mikegarrison said:

The way it is done is to use PD design tools to basically create the design yourself. See how close you came to the data you know, and redo it in a loop until it converges.

PD design tools are not really "back of the envelope", but in a sense they are a more sophisticated, calibrated version of "back of the envelope". They still are not a detailed design, which is the step you do once a PD design gets the go-ahead for further development.

Sometimes you come up with the answer that the claimed performance is unlikely to be achieved, and that's also an educational outcome.

It's different with a design that is actually in service, because in that case if you come up with the answer that the performance can't be achieved and yet it is clearly being achieved in service, then you know your tools need fixing. Real world data trumps all.

Apologies for the slight derailment, but what is meant by the term, "PD design tools?" Google is not helpful here and I assume you're not talking about proportional-derivative controllers or physical design in the electronic context. Are they things like Roskam Class 1 / Class 2 methods?

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18 minutes ago, Silavite said:

Apologies for the slight derailment, but what is meant by the term, "PD design tools?" Google is not helpful here and I assume you're not talking about proportional-derivative controllers or physical design in the electronic context. Are they things like Roskam Class 1 / Class 2 methods?

"preliminary design"

I am not familiar with Roskam, but a quick Google suggests that yes, these are PD design methods.

Edited by mikegarrison
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I started watching the presentation an got to the questions. There is no new stuff there, right? Small details about Raptor 2, fancy animation, back to back refueling (which the change every year or so). I started watching the questions, but they seem boring, too. Any juciy bits there?

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11 minutes ago, Elthy said:

I started watching the presentation an got to the questions. There is no new stuff there, right? Small details about Raptor 2, fancy animation, back to back refueling (which the change every year or so). I started watching the questions, but they seem boring, too. Any juciy bits there?

The presentation was definitely the better part, the most remarkable answers were to EDA, Berger, NSF and Brownsville Herald

 

Here's the transcript:

https://www.reddit.com/r/SpaceXLounge/comments/sppj0m/rough_transcription_of_the_presentation/

 

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Yeah, but the rats' nest on R1 was significant. I wouldn't be surprised if R2 were over 10% lighter overall.

Edit: For comparison, if Blue Origin were to build a 10 diameter (approx outer diameter of Superheavy outer engine ring) vehicle, they could fit perhaps 12 fixed and 3 or 4 gimbaling engines with a total of 3914tf thrust.

That'd barely more than half the mass of a Starship Superheavy stack at the same TWR, and because the ISP is lower and each engine is individually heavier than the equivalent raptor it would be even less capable than that.

Raptor is an incredible engine.

Edited by RCgothic
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Good news on the Boca Chica enviromental assestment! Quoting a quite trustable insider:

"Final PEA is likely to be released on anticipated date of March 12. Approval will be given based on several conditions, and milestone achievement and accedence of conditions."

Looks like it's going to be a mitigated FONSI

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21 minutes ago, Beccab said:

Good news on the Boca Chica enviromental assestment! Quoting a quite trustable insider:

"Final PEA is likely to be released on anticipated date of March 12. Approval will be given based on several conditions, and milestone achievement and accedence of conditions."

Looks like it's going to be a mitigated FONSI

Ayyyyy!

Happy days.

Edited by KSK
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11 hours ago, tater said:

FLRyFYNXsAARBSt?format=jpg

 

Current R2 production is about 5 per week. in 1-2 months, 7 per week.

How in the world do they go from 1 to 2 with such a change in plumbing/wiring?

If we assume all of that was necessary for 1 to work, it just doesn't look like everything is there on 2.  (Here's where I express my ignorance of rocket parts) - the streamlined thingy at the top of 2 looks like something that could be on 1, but under that giant manifold thing sitting at the top of 1.  IF that manifold thing was necessary - doesn't it come with a lot of plumbing, and might all that be added back to a working 2?

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1 minute ago, JoeSchmuckatelli said:

How in the world do they go from 1 to 2 with such a change in plumbing/wiring?

If we assume all of that was necessary for 1 to work, it just doesn't look like everything is there on 2.  (Here's where I express my ignorance of rocket parts) - the streamlined thingy at the top of 2 looks like something that could be on 1, but under that giant manifold thing sitting at the top of 1.  IF that manifold thing was necessary - doesn't it come with a lot of plumbing, and might all that be added back to a working 2?

A lot of the stuff on 1 was not exactly for making the rocket 'go', but for measuring what's going on inside. They needed to know if every part of the engine was working the way they wanted and expected it to, and once they verified that they no longer needed so many sensors on every part.

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I’m guessing a lot of the rats nest was for engineering sensors, so that they could monitor what was happening *everywhere”. Not necessary with R2, now that they understand R1. 
 

Columbia had a lot more sensors than the other Shuttles on board, being the first. That data was invaluable in piecing together what happened. If it happened to another shuttle they may have never figured it out, or it would certainly have taken longer

E. Ninja’d by my wordiness 

Edited by StrandedonEarth
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1 minute ago, cubinator said:

A lot of the stuff on 1 was not exactly for making the rocket 'go', but for measuring what's going on inside. They needed to know if every part of the engine was working the way they wanted and expected it to, and once they verified that they no longer needed so many sensors on every part.

Interesting; I did not know that.  So - they'd have a pipe feeding a something, then another something to measure its work and wires to report on the findings?

Hmm.

Is that a normal part of rocket design -- or something SX did b/c R1 is effectively a prototype (a working prototype, but still a development article)?

Just now, StrandedonEarth said:

E. Ninja’d by my wordiness 

No - it adds, thanks.  Did not know that about Columbia.  Now I have a point of reference to try to google different Shuttle engines and see what I can learn.

Thanks!

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Edit - okay, googling is a mess.  Most people just post "Shuttle Engine" or "Shuttle Rocket" and don't distinguish... and I don't know enough about what I'm seeing to differentiate.

If someone stumbles across (or already knows) where to see the differences between Columbia's engines and later models, I'd love to see it!

 

(I find text descriptions, but not many good pictures)

  • The space shuttle main engine transitioned from its first manned orbital flight configuration to a phase II configuration in 1983. The phase II engine logged 231 engine flights and included improvements to the controller to increase memory, main injector improvements, turbine blade improvements within the turbopumps and additional nozzle insulation.
  • The engine transitioned to Block I configuration in 1995 with significant changes including a two-duct powerhead, an alternate high-pressure oxidizer turbopump featuring ceramic ball bearings, a single tube heat exchanger and improved hot gas sensors.
Edited by JoeSchmuckatelli
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