For Questions That Don't Merit Their Own Thread

[K^2]

1 hour ago, ARS said:

Because other nations knows how to do asparagus staging

Is it asparagus without the cross-feed, though? 

[kerbiloid]

5 hours ago, ARS said:

Because other nations knows how to do asparagus staging

Absolutely.

Spoiler

(Not that it ever flied, of course...)

 

[DDE]

5 hours ago, kerbiloid said:

Absolutely.

  Reveal hidden contents

(Not that it ever flied, of course...)

 

Mustard has entered the chat.

Spoiler

 

[magnemoe]

16 hours ago, kerbiloid said:

Absolutely.

  Hide contents

(Not that it ever flied, of course...)

 

The Soviets was playing KSP here decades before the game started developing. 
Its just looks so totally Kerbal and has launched rockets a lot like this.

KSP give an wrong impression of how cross feed would work. You can not pump fuel from one tank to another, first the tank in the next stage will be full but the booster will get less and less fuel, add other reasons. 
That had to happen is that you will have valves, you have pipes for fuel and oxidizer from booster to core stage engines, valve on the booster,  one regulating valve on manifold and probably an one way valve to prevent flow back to booster or flow between engines if pipe feed multiple. before separation, open valve to internal tank then close the valves on booster and on manifold, disconnect pipe and then separate, you can burn the booster for some time after cutting the connection. 

[K^2]

6 hours ago, magnemoe said:

KSP give an wrong impression of how cross feed would work. You can not pump fuel from one tank to another, first the tank in the next stage will be full but the booster will get less and less fuel, add other reasons. 
That had to happen is that you will have valves, you have pipes for fuel and oxidizer from booster to core stage engines, valve on the booster,  one regulating valve on manifold and probably an one way valve to prevent flow back to booster or flow between engines if pipe feed multiple. before separation, open valve to internal tank then close the valves on booster and on manifold, disconnect pipe and then separate, you can burn the booster for some time after cutting the connection. 

Yeah, you definitely have to resolve any cross-feed in engine plumbing, and not by feeding from tank to tank. That said, are there any configurations that do even that? Boosters in Soyuz  and earlier R7 family have completely independent fuel systems. Energia and Long March rockets seem to have followed suit. Proton is interesting in that the six engines have their own fuel tanks while sharing an oxidizer tank, but it's still a fixed connection with no switching between tanks, not to mention that it's all part of a single stage. Delta IV and Ariane 5 fly with solid boosters, so no cross-feed there. It was, apparently, considered for Falcon Heavy, but canceled, so that's another rocket with independent fuel system for each booster. Was there ever an actual rocket with cross-feed?

[kerbiloid]

10 hours ago, magnemoe said:

The Soviets was playing KSP here decades before the game started developing. 

They did it right in metal.

***

What do you call "the 1st stage" and "booster" at all, when all (four) first stages are two-staged themselves, and there is no central core at all?

Spoiler

To the right - the original UR-500 (the future Proton).
Four two-staged ICBM UR-200 (to the left) and the fifth one as upper stage.
So, you first drop 4 first-first stages, then 4 second-first stages, then ignite the last one.

 

10 hours ago, magnemoe said:

KSP give an wrong impression of how cross feed would work. You can not pump fuel from one tank to another, first the tank in the next stage will be full but the booster will get less and less fuel, add other reasons. 

No problem. UR-700 was designed with propellants crossfeed, by placing the additional  tanks on top of lateral boosters, in the nosecones and below.
Every couple of lateral boosters (3x2) would be feeding the corresponding  internal 1st stage booster (3x1).
It's exactly an asparagus rocket. Asparagus of all asparaguses.

Spoiler

 

Edited March 7, 2021 by kerbiloid

[Jacke]

2 hours ago, K^2 said:

Yeah, you definitely have to resolve any cross-feed in engine plumbing, and not by feeding from tank to tank. That said, are there any configurations that do even that?

Saturn I's first stage (S-I) had 9 tanks, central one same diameter as Jupiter, 8 outer ones same diameter as Redstone, 4 outer ones RP-1, rest LOX; built that way to continue using same jigs and not have to master making wider tanks at that moment.  Interconnect under the tanks merge all similar propellant tanks, then provided feed to the 8 H-1 engines.  Had engine-out capability after certain points in the ascent and would go for a longer burn on the remaining engines.  Saturn IB was the same with its S-IB.

[kerbiloid]

Proton pumps oxidizer from the central core to the laterals.

[DDE]

5 hours ago, K^2 said:

Yeah, you definitely have to resolve any cross-feed in engine plumbing, and not by feeding from tank to tank. That said, are there any configurations that do even that? Boosters in Soyuz  and earlier R7 family have completely independent fuel systems. Energia and Long March rockets seem to have followed suit. Proton is interesting in that the six engines have their own fuel tanks while sharing an oxidizer tank, but it's still a fixed connection with no switching between tanks, not to mention that it's all part of a single stage. Delta IV and Ariane 5 fly with solid boosters, so no cross-feed there. It was, apparently, considered for Falcon Heavy, but canceled, so that's another rocket with independent fuel system for each booster. Was there ever an actual rocket with cross-feed?

Not in the truest sense where both stages have motors, no. There have been several drop tank designs, including Briz and Fregat/Flagman,

but if you include those you might as well include the Shuttle.

[magnemoe]

3 hours ago, kerbiloid said:

They did it right in metal.

***

What do you call "the 1st stage" and "booster" at all, when all (four) first stages are two-staged themselves, and there is no central core at all?

  Hide contents

To the right - the original UR-500 (the future Proton).
Four two-staged ICBM UR-200 (to the left) and the fifth one as upper stage.
So, you first drop 4 first-first stages, then 4 second-first stages, then ignite the last one.

 

No problem. UR-700 was designed with propellants crossfeed, by placing the additional  tanks on top of lateral boosters, in the nosecones and below.
Every couple of lateral boosters (3x2) would be feeding the corresponding  internal 1st stage booster (3x1).
It's exactly an asparagus rocket. Asparagus of all asparaguses.

  Hide contents

 

Wait, it had separate 6 separate top tanks who feed into the 3 cores, on the expanded view you can see the connections and how the tanks was different. 
This reminds me a bit of the KSP tricks of putting fuel tanks on top of SRB. Definitely simpler as you only need one valve who can close then flow stops. However you might then get an cold gas trust then they disconnect but this might be an benefit.  Was the huge grind fin for separation? Not sure how the second stage works on this. Is it one oxidizer tank and 3 fuel tanks and engines proton style? 
I see it has an 3rd stage inside the fairing. 

[DDE]

4 minutes ago, magnemoe said:

Not sure how the second stage works on this. Is it one oxidizer tank and 3 fuel tanks and engines proton style?

Yeah, the third stage (to use original terminology) is a stripped-down Proton.

[magnemoe]

1 hour ago, DDE said:

Yeah, the third stage (to use original terminology) is a stripped-down Proton.

Yes is obvious that they worked with diameter limits, 9 stacks at bottom, 2x3 boosters and 3 core. then 3 smaller fuel tanks around the oxidizer core. 
And yes it reminds me a bit about early mun landers in KSP then you only have 1.25 meter tanks. 

[DDE]

Bit of a mini-thread: how to create the biggest nozzle extension?

So, at least according to this, the first stage lOx tankage on the Sea Dragon would act as a nozzle extension for the second stage:

So, a question: is it possible to use a sectioned interstage as a second nozzle extension in addition to a conventional RL-10B-2's "scout's cap"? As I understand, the requirements this far away from the nozzle throat are modest, so the uncooled, standard structural material is sufficient.

Spoiler

 

[kerbiloid]

3 hours ago, magnemoe said:

Wait, it had separate 6 separate top tanks who feed into the 3 cores

If you mean UR-700, it had a triple core surrounded with triple "parablocks" (i.e. connected together twin boosters).

All nine were same boosters with same engines and tanks, but the six external were carrying additional tanks on top to feed the corresponding core booster with any of propellant components.
Obviously, the acceleration should make the process easier even without pumps, because it would just refill the core tanks, rather than directly feed the core engines.

So, on start there "were" nine full-tank boosters, after separation there "were" 3 fully fueled core boosters.

The upper stage was similar to the Proton stage, surrounded with three additional ones.

The LK-700 on top also had a central core with three droppable boosters around.

But the fuel exchange was only between the first stage lateral and core boosters.
Of course, as it was hypergolic, it was much easier than if it was cryogenic.

 

The third stage was in later designs replaced with cryogenic and even nuclear stages, to let it lift ~250 t.
This one is the classic design, of nearly Saturn-V capacity.

 

This design may seem strange, but it had its own advantage. All boosters were made of same 4 m Proton cylinders, on same industrial equipment, so it would be built right when it's needed, with no break in Proton manufacturing.

Also like Proton, it could be delivered from any plant to any launchpad by existing railroads, through all existing bridges and tunnels.

3 hours ago, magnemoe said:

This reminds me a bit of the KSP tricks of putting fuel tanks on top of SRB.

SRB has an absolutely different construction from a liquid stage, so it's not good.
While all there boosters and tanks are made of same standard Proton components taken from warehouse in required amounts.

If you don't need UR-700 at the moment, you could keep building Protons out of them.

The same with fuel. You can take as much as you need from the warehouse, as hypergolic fuel can be stored for decades.

Also, unlike Saturn, Energy, Starship, etc, it could be on a duty launchpad for a month and longer as a rescue lunar ship or so.

Edited March 7, 2021 by kerbiloid

[K^2]

8 hours ago, DDE said:

There have been several drop tank designs, including Briz and Fregat/Flagman, but if you include those you might as well include the Shuttle.

Fair call. I wasn't really thinking of drop-tank designs, but they have nearly all the same plumbing challenges as asparagus, so it certainly shows how it can be done.

[magnemoe]

9 hours ago, K^2 said:

Fair call. I wasn't really thinking of drop-tank designs, but they have nearly all the same plumbing challenges as asparagus, so it certainly shows how it can be done.

I think its an huge difference between an orbital rocket and an moon lander then it comes to drop tanks. An huge orbital rocket has fuel flow like an small hydro plant and feed turbo pumps who require constant flow, while an moon lander uses pressure feed engines and  is scaled more like an fighter plane and they have used drop tanks since WW2. All larger planes has multiple fuel tanks and tap them for balance anyway. 

[kerbiloid]

Spoiler

 

 

[DDE]

10 hours ago, magnemoe said:

while an moon lander uses pressure feed engines

Be careful about such claims. Both the 11D411 primary and the 11D412 secondary on the LK were turbopump-fed with some sort of capillary feed system in lieu of ullage motors.

All Soyuz variant main and, if present, backup engines are turbopumped. The Soviets even had them in AA missiles.

[kerbiloid]

LK-700 is also turbopumped, afaik.

[JoeSchmuckatelli]

Time to confidently expose my ignorance:

Do the symbols used in physics have a common understanding, or are they entirely contextual?

 

Example: when reading an article about the cosmological constant, the authors refer to the ^ (lambda) symbol as standing for vacuum energy.  Does the use of lambda stand for vacuum energy only in the equations related to the cosmological constant - and something else in another context? 

 

I'd like to be able to look at the equations in the articles I read and kind of understand what they're getting at, even if I don't have the math background to do the heavy lifting. 

 

 

[Jacke]

14 minutes ago, JoeSchmuckatelli said:

Do the symbols used in physics have a common understanding, or are they entirely contextual?

Mathematics, Physics, and other Sciences get in the habit of referring to specific constants (speed of light, Pi, base of the natural logarithms, etc) or values (distance, speed, velocity, energy, etc.) by single characters, usually draw from the Latin and Greek alphabets, but also the Hebrew alphabet (different infinite values using the first character Aleph with subscript single digits from 0 up) and some special characters, or sometimes one of the previous characters reversed (Math's use of backward's E meaning "Exists", upside-down A meaning "For every")  or on its side (8 on its side meaning the Infinity of Integers or Aleph₀).   It allows the constant or value to be referred to in simple formula.

Even with all those choices, the letters get overloaded and often mean different things in different fields.

Edited March 8, 2021 by Jacke

[JoeSchmuckatelli]

29 minutes ago, Jacke said:

Mathematics, Physics, and other Sciences get in the habit of referring to specific constants (speed of light, Pi, base of the natural logarithms, etc) or values (distance, speed, velocity, energy, etc.) by single characters, usually draw from the Latin and Greek alphabets, but also the Hebrew alphabet (different infinite values using the first character Aleph with subscript single digits from 0 up) and some special characters, or sometimes one of the previous characters reversed (Math's use of backward's E meaning "Exists", upside-down A meaning "For every")  or on its side (8 on its side meaning the Infinity of Integers or Aleph₀).   It allows the constant or value to be referred to in simple formula.

Even with all those choices, the letters get overloaded and often mean different things in different fields.

I guess the follow on question, is: is there a cheat-sheet or maths-to-knucklehead dictionary out there that I can refer to?

[DDE]

31 minutes ago, JoeSchmuckatelli said:

I guess the follow on question, is: is there a cheat-sheet or maths-to-knucklehead dictionary out there that I can refer to?

This seems a good start: List of common physics notations - Wikipedia

[JoeSchmuckatelli]

26 minutes ago, DDE said:

This seems a good start: List of common physics notations - Wikipedia

Cool - never ran across this! 

 

On the page was a reference to 'Jerk' 

Is this legit?  https://en.m.wikipedia.org/wiki/Jerk_(physics)

Note: "Snap, crackle and pop" 

Edited March 8, 2021 by JoeSchmuckatelli

[kerbiloid]

1 hour ago, JoeSchmuckatelli said:

Do the symbols used in physics have a common understanding, or are they entirely contextual?

We, the Russians, do have the Щ-function in the "Mathematical Physics Equations" discipline.

/shch^ja/-function

And Americans don't have such letter in their alphabet, so our mathematical physics equations are better.