What doesn't KSP teach about Rocket Science

[wumpus]

Scott Manley recently made a video explaining "what KSP can teach about Rocket Science" (I don't recommend the video, it drags on and should be obvious to any KSP player.  Watch just about any of his science videos instead).  After that, he tweeted about making a video about "what doesn't KSP teach you".

At the danger of repeating what is in this thead: 

I was wondering "what doesn't KSP teach you about rocket science"?  My ideas:

TURBOPUMPS:   turbopumps aren't *everything* in the design of rocket engines and rockets in general, but the certainly dominate the design.  To the simplest approximation, they *are* the engines.  And they are black boxes in KSP.

Gravity: Meh.  Certainly gravity is "lol fake", but ask anyone about space missions and they will tell you missions that can be described with KSP gravity.  It is only the most extreme and recent missions that have tried the "fuzzy boundries" and "interplanetary superhighway" that occurs when you have real N-body gravity.

physical part failure and stresses: The SpaceX crew lets out a big cheer when Falcon9 survives max-Q (they also cheer sound checks, but there is a reason to cheer for max-Q).  In KSP, this is nothing, and I really think I should understand max-Q.

Most of the rest of the seem irrelevant (I mean, you can't make spaceships like LEGO, and there exists Realism Overhaul for a reason).  But most of the big complaints seem to be fixed through .9, 1.0, and 1.1 (not sure what was left for 1.1).  Using a toy solar system tends to lend to misconceptions (jet powered space planes being the biggest), but anything that can be fixed by mods seems less a danger than things that can't.

So TURBOPUMPS.  And some good reasons for Realism Overhaul.  And a bunch of meh (although you can learn a lot with the existing N-body physics mod (assuming your computer is up to it)).  And max-Q, whatever influence that has on rocket science.

 

 

[PB666]

2 minutes ago, wumpus said:

Scott Manley recently made a video explaining "what KSP can teach about Rocket Science" (I don't recommend the video, it drags on and should be obvious to any KSP player.  Watch just about any of his science videos instead).  After that, he tweeted about making a video about "what doesn't KSP teach you".

At the danger of repeating what is in this thead: 

I was wondering "what doesn't KSP teach you about rocket science"?  My ideas:

TURBOPUMPS:   turbopumps aren't *everything* in the design of rocket engines and rockets in general, but the certainly dominate the design.  To the simplest approximation, they *are* the engines.  And they are black boxes in KSP.

Gravity: Meh.  Certainly gravity is "lol fake", but ask anyone about space missions and they will tell you missions that can be described with KSP gravity.  It is only the most extreme and recent missions that have tried the "fuzzy boundries" and "interplanetary superhighway" that occurs when you have real N-body gravity.

physical part failure and stresses: The SpaceX crew lets out a big cheer when Falcon9 survives max-Q (they also cheer sound checks, but there is a reason to cheer for max-Q).  In KSP, this is nothing, and I really think I should understand max-Q.

Most of the rest of the seem irrelevant (I mean, you can't make spaceships like LEGO, and there exists Realism Overhaul for a reason).  But most of the big complaints seem to be fixed through .9, 1.0, and 1.1 (not sure what was left for 1.1).  Using a toy solar system tends to lend to misconceptions (jet powered space planes being the biggest), but anything that can be fixed by mods seems less a danger than things that can't.

So TURBOPUMPS.  And some good reasons for Realism Overhaul.  And a bunch of meh (although you can learn a lot with the existing N-body physics mod (assuming your computer is up to it)).  And max-Q, whatever influence that has on rocket science.

You like your turbopumps. 

1. structural design. In ksp parts are joined either at node attach points or surface attach point, In real life attachment of parts generally occurs near the outside rim for stabikity. 

2. Part scalability for function, particularly true when talking about mounts and off sets. 

Without these critical features rockets are no more thsn out of control bombs. 

3. Zero height adapters, can you make a falcon 6, 7, 8 or nine rocket without using a radial attachment point, illmdesigned for the task of engine mounts

4. The ability to run over the stated maximum thrust. 

5. Reaction wheels, cannot comoensate indefinitely without rcs 

KSP would be better if you could design in the game your tanks including the structure critical joining surfaces, if you did it right you would get a dV bonus over the stock tanks. 

In addition we could have and engine design gui whereby you designed your engine up an engine bay, like on the falcon ir saturn V 1 st stage. Again you get some bonus for a good design. 

There could be a variety of interstage couplings. 

 

[James Kerman]

KSP does not teach the difficulties involved with fuels.  It would be interesting to deal with cryogenics and boil-off.

[kerbiloid]

- Ullage motors to allow restart in zero-G. (Implemented in a couple of mods, but not sure if stiil works).

- Engine fuel mode dynamic switch (like in RD-701: (Kerosene+LH2)/LO2 on start, pure LH2+LO2 after max-Q).

- Pressure feed instead of turbopumps (easily implemented manually by adding 3rd resource (LqdNitrogen or LqdHelium) to the tank and engine definitions)

- SRB in-situ recharge

- Spots of radioactive fallout if you just drop your Nervas around.

- Radiation at all (implemented in Kerbalism and partially in KSPI-E and Kappa-Ray)

[FleshJeb]

1 hour ago, kerbiloid said:

Radiation at all (implemented in Kerbalism and partially in KSPI-E and Kappa-Ray)

Thanks for this. My compulsion to put shadow-shields on NERVs is not being satisfied by the powers of greebling and roleplay.

[KSK]

4 hours ago, wumpus said:

Scott Manley recently made a video explaining "what KSP can teach about Rocket Science" (I don't recommend the video, it drags on and should be obvious to any KSP player.  Watch just about any of his science videos instead).  After that, he tweeted about making a video about "what doesn't KSP teach you".

At the danger of repeating what is in this thead: 

I was wondering "what doesn't KSP teach you about rocket science"?  My ideas:

TURBOPUMPS:   turbopumps aren't *everything* in the design of rocket engines and rockets in general, but the certainly dominate the design.  To the simplest approximation, they *are* the engines.  And they are black boxes in KSP.

With respect, I disagree. I would argue that injectors fit that definition better and combustion chamber and nozzle design to a lesser extent. You can have the best turbopumps in the world but without an injector that can cope with whatever propellant flow your pumps can create your rocket isn't going anywhere. And without a properly designed nozzle, it's not going anywhere fast.

Turbopumps are certainly important for the highest performance engines (read - most lifter engines) but you can get very reasonable performance out of a pressure fed design which (obviously) doesn't require any pumps at all.

As for what KSP doesn't teach you about rocket science? In a word - details.

I don't have any experience with RO or KerbalEdu but stock KSP only teaches you about space vehicle design in very broad strokes, it teaches you about the consequences of the rocket equation whilst carefully avoiding mentioning it in so many words. It teaches you some of the nomenclature around orbital mechanics and a very appealing visual tool to experiment with them. It teaches you that parachutes don't work too well in a vacuum.

But once you get beyond those broad strokes, KSP is essentially magic. Attach a magic engine to a magic fuel tank, maybe add some fins and a nosecone and you've got a rocket. No need to worry about propellant chemistry, pogo, slosh, combustion instability, chamber pressures, cavitation or injector design. No need to think about nozzle geometry. No need to choose between radiative cooling, ablative cooling, curtain cooling or regenerative cooling. Balloon tanks, isogrids, thrust assemblies, the structural and material complexities of building something incredibly light that can still cope with tremendous forces and extreme temperature gradients.

Astronavigation, attitude control, attitude determination, tracking and guidance - all hidden behind the magic Map Screen and the magic Navball.

Communication systems, life support systems, capsule design in general - not dealt with at all, or hidden by magic crewmembers that don't need to deal with those harsh realities.

 

[Creature]

28 minutes ago, KSK said:

As for what KSP doesn't teach you about rocket science? In a word - details.

 

This sums it all up very nicely.

Overall what KSP teaches and how it inspires is great, but there's a downside to it which has troubled me for a while now after reading these forums for a few years now. Especially now, since I've personally been involved in real world engineering projects.

What we do in KSP is nothing like reality. Everything in real world is thousands of times harder, more tedious and takes a massive amount of work. I don't know much about aerospace engineering, but I bet that every single nut and bolt has been thoroughly tested, there has been years of materials studies behind it and there's probably a company somewhere that employs a dozen people who primarily manufacture these bolts. Of course everything looks nice and efficient once it's done, but there's a huge amount of work done behind the scenes. What KSP gives us is a nice dream, but it doesn't prepare anyone for working in engineering in any meaningful way.

[KSK]

Thanks Creature.

I should also say that KSP's lack of detail is generally OK in my opinion - it is after all a game, even with additional reality mods tacked on. I do sometimes wonder whether a bit more attention to detail behind the scenes (and so hidden to the players) might give Squad a better, more coherent framework to work with when it comes to balancing parts and adding new parts, but on the other hand, that would also involve a large amount of work from a fairly small team for something that is going to be largely invisible to players. Probably not worth it.

However, I do sometimes think that folks on this forum get a bit carried away with the fact that they're playing 'a game about rocket science' and on some threads I've noticed a distinct whiff of elitism or smug self-satisfaction that they're playing a 'hard' game and that KSP players are somehow better or smarter than others because of that.

Easy to do, and I have to admit that I got a bit carried away in my own head when I started playing KSP and finding that I 'could do orbital mechanics' (lol). However, I did also work out fairly quickly that I'd be utterly sunk without the Map screen to help me. Then I started writing my KSP story and reading up a bit more on actual spaceflight to try and add a bit of authenticity to that story. Even at a fairly descriptive level - I recommend the Apollo flight journals  - the sheer number of things that are glossed over or abstracted away in KSP became very obvious.

Edited May 25, 2016 by KSK

[PB666]

2 hours ago, KSK said:

Thanks Creature.

I should also say that KSP's lack of detail is generally OK in my opinion - it is after all a game, even with additional reality mods tacked on. I do sometimes wonder whether a bit more attention to detail behind the scenes (and so hidden to the players) might give Squad a better, more coherent framework to work with when it comes to balancing parts and adding new parts, but on the other hand, that would also involve a large amount of work from a fairly small team for something that is going to be largely invisible to players. Probably not worth it.

However, I do sometimes think that folks on this forum get a bit carried away with the fact that they're playing 'a game about rocket science' and on some threads I've noticed a distinct whiff of elitism or smug self-satisfaction that they're playing a 'hard' game and that KSP players are somehow better or smarter than others because of that.

Easy to do, and I have to admit that I got a bit carried away in my own head when I started playing KSP and finding that I 'could do orbital mechanics' (lol). However, I did also work out fairly quickly that I'd be utterly sunk without the Map screen to help me. Then I started writing my KSP story and reading up a bit more on actual spaceflight to try and add a bit of authenticity to that story. Even at a fairly descriptive level - I recommend the Apollo flight journals  - the sheer number of things that are glossed over or abstracted away in KSP became very obvious.

Yeah, and the game also has a history, building rockets in the early versions anything like a NASA sized rocket was really really hard, since 0.25 its become somewhat easier. And while KSP did not have system failures it had the kraken, which often depended on how you built.

[kerbiloid]

Also due to the old KSP aerodynamics, there were planes without engines, made just from structural panels and wings, and it was harder to land them, than to lift.
At least one of them even could inject into orbit.

[wumpus]

While "details" are easily the heart of engineering, I would go so far as to limit what KSP can teach you into a small set of bullet points:

• The rocket equation
• Astronavigation using 2-body gravity (with lots of help from an unseen or heard from "Houston"*)
• A little aerodynamics (and emphasizing the "little")

While I like "details" it also excludes entire disciplines

• chemistry (even with realism overhaul)
• mechanical engineering (yes, there are struts.  But that doesn't begin to cut it)
• electrical engineering (sensors, controls, communications, anything)
• materials.  Everything in KSP is unobtanium with some temperature requirements.
• logistics.  All those built parts don't all show up and self assemble into a rocket anywhere but Kerbin.

To be honest, nobody at NASA does everything on the list, and very, very few deal with more than a single bullet point.  Chemistry might *look* like a solved problem, then the guys at Spacex decide to change the temperature of the fuels (and oxidizer) which certainly changes how they will flow through pipes and whatnot.  And then they might even bring up methane.  And there seems to be a dozen different varieties of hydrazine used in space, I'm sure each one is carefully selected for the application.

But I strongly suspect that if you made great turbopumps, you could farm out the rest and still have a decent space program.

* Somebody supplies Kerbal vessels with all that information even if they don't have KE installed.  Some kerbals whisper of a mysterious unseen city on Kerbin known only as "Houston".

[PB666]

47 minutes ago, wumpus said:

While "details" are easily the heart of engineering, I would go so far as to limit what KSP can teach you into a small set of bullet points:

• The rocket equation
• Astronavigation using 2-body gravity (with lots of help from an unseen or heard from "Houston"*)
• A little aerodynamics (and emphasizing the "little")

While I like "details" it also excludes entire disciplines

• chemistry (even with realism overhaul)
• mechanical engineering (yes, there are struts.  But that doesn't begin to cut it)
• electrical engineering (sensors, controls, communications, anything)
• materials.  Everything in KSP is unobtanium with some temperature requirements.
• logistics.  All those built parts don't all show up and self assemble into a rocket anywhere but Kerbin.

To be honest, nobody at NASA does everything on the list, and very, very few deal with more than a single bullet point.  Chemistry might *look* like a solved problem, then the guys at Spacex decide to change the temperature of the fuels (and oxidizer) which certainly changes how they will flow through pipes and whatnot.  And then they might even bring up methane.  And there seems to be a dozen different varieties of hydrazine used in space, I'm sure each one is carefully selected for the application.

But I strongly suspect that if you made great turbopumps, you could farm out the rest and still have a decent space program.

* Somebody supplies Kerbal vessels with all that information even if they don't have KE installed.  Some kerbals whisper of a mysterious unseen city on Kerbin known only as "Houston".

Kouston, ke kave a kroblem.

[cantab]

3 hours ago, wumpus said:

* Somebody supplies Kerbal vessels with all that information even if they don't have KE installed.  Some kerbals whisper of a mysterious unseen city on Kerbin known only as "Houston".

Isn't that just the Tracking Station? And

Spoiler

there's an additional dish at the other space centre.

 

[PB666]

1 hour ago, cantab said:

Isn't that just the Tracking Station? And

  Reveal hidden contents

there's an additional dish at the other space centre.

 

The two stations are relatively close and not on a pole, so how donthey track you when they are on the side of the planet facing away. 

 

Of course kerbal could have as part of the game the launching of tracking satellites. also. if you travel to another planet, your orbital period differs, so at some point kerbin is on the other side of kerbol, and blocked. That would mean that before you go. To solve this you need to satellites in kerbin circum kerbol orbit that are 120' from kerbins position so that all parts of the system can be tracted. Make two stations and put all the f grade kerbols on them. 

[YNM]

Personally, advanced orbital maneuvers. I mean, like, Cassini or Rosetta.

But practically a lot of technologies and limitations. Time delay, radiation, life support...

That being said, the game is already hard for early starters !

Edited May 26, 2016 by YNM

[magnemoe]

8 hours ago, PB666 said:

The two stations are relatively close and not on a pole, so how donthey track you when they are on the side of the planet facing away. 

 

Of course kerbal could have as part of the game the launching of tracking satellites. also. if you travel to another planet, your orbital period differs, so at some point kerbin is on the other side of kerbol, and blocked. That would mean that before you go. To solve this you need to satellites in kerbin circum kerbol orbit that are 120' from kerbins position so that all parts of the system can be tracted. Make two stations and put all the f grade kerbols on them. 

On earth we have the deep space network with tracking stations on multiple continents. 
Nobody uses satellites to receive data from deep space probes. 
Simpler to assume its 2-3 other set of receivers on kerbin. 

An upcoming update will require line of sight and antenna size for missions. so during night on Duna you will not be able to transmit science. Think you can still control. An satelite in Duna orbit will solve this. as long as it has line of sight to both you and Kerbin. Has the benefit that you can put the big antenna needed to communicate back in space. 
 

[PB666]

1 hour ago, magnemoe said:

On earth we have the deep space network with tracking stations on multiple continents. 
Nobody uses satellites to receive data from deep space probes. 
Simpler to assume its 2-3 other set of receivers on kerbin. 

An upcoming update will require line of sight and antenna size for missions. so during night on Duna you will not be able to transmit science. Think you can still control. An satelite in Duna orbit will solve this. as long as it has line of sight to both you and Kerbin. Has the benefit that you can put the big antenna needed to communicate back in space. 
 

BUt there is no way in the game to add deep space tracking network, so . . . . .  .

You would need

1. Transmission lines

2. Remote site parabolic antenna arrays

3. Satellite telecommunications or undersea telecommunications from areas that are not directly connected by land.

There is a satellite communication network around Mars.

 

 

Edited May 26, 2016 by PB666

[wumpus]

Of course, KSP gives you full mapping, tracking, and computes a target trajectory and sticks it on the navball (at least in my games) long before you develop jet engines.  Even through the Apollo era, windows had marked and calibrated etchings that were used to line up burns visually (Buzz Aldrin's famous PhD thesis was on "visual" orbital docking procedures).

I'm not saying that a mod that forces you to launch from the cock view would be a great idea.  I have felt that the ability to pre-compute a mission (starting with a node on the pad) would be a great idea, and such a thing would be all but mandatory for more primitive missions (NASA had specific launch windows for landing at each potential Moon landing spot).  I would assume that you would need such a thing (although a "proper" rocket scientist could figure it out with a period correct slide rule from the information given*).  I'm pretty sure that computing a maneuver node is trivial now (and was for Shuttle Launches, even if accounting charged the budget an arm and a leg for computer time), a significant chunk of time on a CDC6600 for Apollo, and a *lot* of man**-hours on a slide rule under mercury and vanguard.  Don't forget the rocket science in the maneuver nodes.

* Do we need an astronomical observatory mod?  I don't think KSP ever gives correct angles for position of planets in the sky, so to a certain degree you have to wing it.  I know there is a recent thread complaining about this lack of information and that it exists in KE and mechjeb (and is presumably used in the creation of various launch window calculators).  Note that KSP gets a certain advantage here since 2-body gravity is exact and NASA had at least some uncertainty with the voyager trajectories (I'm sure the burn uncertainties were *much*, *much* worse, but wanted to point out the difference).

** Or likely woman-hours.  The more educated wives and girlfriends of R&D types during WWII were dragged into doing these tedious calculations.  No idea if they had already left/been replaced.  There were still enough around that when computers became available that often these women became the first computer programmers.

[PB666]

Yeah the progression is silly, that is one of my major beefs with game play, you already land on the moon and finally you get the first wheel, really? F'give us a donkey cart at least, childs wagon. I forgot there are no animals on kerbin, guess we will have to enslave cadets as wagon engines. 

Seriously the launch pad should not be available until you have flown a certain distance and some carry missions with the aero stuff. But, alas, it is a space exploration game.......... i need wheels, worse of than fred flintstone.. 

[todofwar]

On Wednesday, May 25, 2016 at 6:29 PM, wumpus said:

Chemistry might *look* like a solved problem

I certainly hope not for the sake of my career past grad school

[todofwar]

The entire science system. The amount of lab work and simulations that NASA does probably trumps the amount of science gotten in space, and deciding which instruments to send requires tons of planning based on what you actually want to study and what instruments can be loaded onto a probe. And actually getting the data is step one out of ten.

But overall KSP is probably as good as any other Sim out there. Anyone actually want to run a city? It's not as easy as simcity. Or managing an empire, or even the most "realistic" war games. But it is hopefully inspiring people to ask, why can't we do that mission in real life? Who will then go on to find out just how to do it. And if not, they hopefully learn about the importance of [redacted for getting too political]

[wumpus]

14 hours ago, todofwar said:

I certainly hope not for the sake of my career past grad school

I just meant just for the fuels used in rocket science.  Spacex's plan of using methane is pretty big as fuels have been nearly steady since roughly the 1960s (especially with Proton and its massive UBMH stage being phased out).  I doubt the guys doing materials science want to be stuck with 1960s chemicals, and that has a huge effect on rocket science.

[PB666]

15 hours ago, todofwar said:

The entire science system. The amount of lab work and simulations that NASA does probably trumps the amount of science gotten in space, and deciding which instruments to send requires tons of planning based on what you actually want to study and what instruments can be loaded onto a probe. And actually getting the data is step one out of ten.

Well if you can imagine how much effort it took to find a way to get Rosetta to 67p with the budget they had allotted.

http://www.telegraph.co.uk/news/science/space/11222693/The-Rosetta-spacecraft-mission-an-animated-journey-to-the-comet.html

 

[todofwar]

7 minutes ago, PB666 said:

Well if you can imagine how much effort it took to find a way to get Rosetta to 67p with the budget they had allotted.

http://www.telegraph.co.uk/news/science/space/11222693/The-Rosetta-spacecraft-mission-an-animated-journey-to-the-comet.html

 

Exactly. And don't forget, they had a pretty limited window to get data from the lander, but even that will probably be extensively studied for a long time. Data analysis is the less glamorous, more grueling, more soul crushing part of science that never gets mentioned but is probably the most important step. 

[PB666]

51 minutes ago, todofwar said:

Exactly. And don't forget, they had a pretty limited window to get data from the lander, but even that will probably be extensively studied for a long time. Data analysis is the less glamorous, more grueling, more soul crushing part of science that never gets mentioned but is probably the most important step. 

But, it would have been great if they could have grabbed a kilo of sample and put it in a circular orbit so that it could be retrieved. It only needed 2 m/s to break orbit.