Pet peeve: orientation during atmospheric re-entry.

[Vanamonde]

Here's the thing that's bugging me in version 1.x.

This is the kind of lander it is useful to build. Fuel tank, engines, landing gear, and most other working parts below the capsule.

But with drag and mass distributed the way they are currently, during re-entry, landers like this are subjected to an ultimately irresistable force which flips them around so that they are falling nose-first.

This renders the engine unavailable for braking burns, and forces the player to try to guess whether a heat shield needs to be mounted on the bottom or the top.

After the ship slows to the point that it's safe to deply chutes, doing so forces it once more reverse itself, this time violently.

Note the 6Gs or more this unwanted manuever imposes on the craft.

I'm not saying its unrealistic for the parts to behave this way with their current attributes. What I am saying is that it's undesireable from a gameplay standpoint for the player's landers to forcibly flip around twice during reentries, and those part attributes are arbitrary and can be changed. How much work it would take to fix this, I do not know. But I really don't like it.

[Starwaster]

Here's the thing that's bugging me in version 1.x.

This is the kind of lander it is useful to build. Fuel tank, engines, landing gear, and most other working parts below the capsule.

http://i.imgur.com/C68CoyM.png

But with drag and mass distributed the way they are currently, during re-entry, landers like this are subjected to an ultimately irresistable force which flips them around so that they are falling nose-first.

http://i.imgur.com/vBKfGiq.png

This renders the engine unavailable for braking burns, and forces the player to try to guess whether a heat shield needs to be mounted on the bottom or the top.

http://i.imgur.com/8l6AmlD.png

After the ship slows to the point that it's safe to deply chutes, doing so forces it once more reverse itself, this time violently.

http://i.imgur.com/jeIlp0k.png

Note the 6Gs or more this unwanted manuever imposes on the craft.

I'm not saying its unrealistic for the parts to behave this way with their current attributes. What I am saying is that it's undesireable from a gameplay standpoint for the player's landers to forcibly flip around twice during reentries, and those part attributes are arbitrary and can be changed. How much work it would take to fix this, I do not know. But I really don't like it.

What kind of solution are you looking for?

A stable design or pre-1.0 drag behavior? Because you can get the latter back if you Alt-F12 then click Physics then Drag.

'Apply Drag As Acceleration Instad of Force' (sic) is basically how drag was applied prior to KSP 1.0....

And you also have to enable 'Replace Drag Cubes With Spherical Model'

[PDCWolf]

So, you are suggesting getting the behavior back to something you yourself imply is unintuitive and unrealistic just for gameplay convenience?. I'm against.

Those configurations are working "as expected", and that's better for new players, like a dart going nose first which is expected, but you suggest a dart being able to fly tail first "for gameplay convenience".

Those landers have a lot of design issues too, and you don't even need a lander for Kerbin either but I guess you want to keep some funds for recovery, in which case that's a challenge you should face: "I want to bring a lot of rocket back, it's aerodynamic properties are bad and make for a dangerous reentry and landing process" "I know, better change the drag system to accomodate for my mistakes instead of facing a challenge".

[tater]

Why would anyone expect a lander like that to reenter in one piece?

[Starwaster]

People, I don't think he's asking that the game be changed to suit him, he's just asking how he can fix things for himself.

Why would you be against that?

It's his sandbox he can do as he likes in it.

[Tarmenius]

Why would anyone expect a lander like that to reenter in one piece?

Why would anyone expect it to not be able to reenter in one piece? Sure we all know that reentry heating is a thing, but how is anyone supposed to know beforehand that their lander is going to flip over and potentially roast on return to Kerbin? With the current Science system, players are encouraged to bring back the instruments (and other parts, thanks to Recovery). Yet the aerodynamic and heating models make that difficult to accomplish and the game gives us no tools to predict that difficulty. The solution of "Move all Science to the pod and ditch the equipment before reentry" is not something a first-time-to-the-Mun player is likely to think of naturally and they won't realize their mistake until it's too late. I think this highlights a fault in game design and Vanamonde is right to point it out.

Sadly, I don't have any good solutions. As I see it, either include some tools for the player to make sense of the atmosphere and heating models, or simplify the models themselves. Both would require significant amounts of work and each would displease a segment of the playerbase.

[Lelitu]

The solution of "Move all Science to the pod and ditch the equipment before reentry" is not something a first-time-to-the-Mun player is likely to think of naturally and they won't realize their mistake until it's too late.

Sadly, I don't have any good solutions. As I see it, either include some tools for the player to make sense of the atmosphere and heating models, or simplify the models themselves. Both would require significant amounts of work and each would displease a segment of the playerbase.

I think you nailed the problem there.. new players won't realize the science can be taken out of the experiments..

The solution here is to make it much clearer that you can and should take the science out, and put it in the pod before returning to kerbin. It's much cheaper to develop, much less annoying to established players.

When I first started, I didn't know the science could be removed, so I always built the science modules between the heatshield and pod, which for a light load in kerbin will safely return.

That worked pretty well until I knew about storing results in the command pod.

[DundraL]

Well from what I see, what you have is a design problem: Those fuel tanks act like giant fins when empty. If you kept them full I bet it would fly like you wanted.... but why haul dead weight around? Try a lander can with a heatshield on bottom with the tank above it. Thats what I usually do, as it keeps the CoM high on ascent and low on decent. That and it reduces the need for ladders etc.

Edited June 15, 2015 by DundraL

[Vanamonde]

What kind of solution are you looking for?

It is my preference rather than an insistence, but I would like the mass/drag of the parts adjusted so that this doesn't happen.

So, you are suggesting getting the behavior back to something you yourself imply is unintuitive and unrealistic just for gameplay convenience?.

Yes. In my opinion, gameplay should trump realism, if the two conflict. And what's more, anyone who uses warp rather than fly multi-month missions in real time agrees with me, whether you'll admit it or not.

"I know, better change the drag system to accomodate for my mistakes instead of facing a challenge".

I am expressing one player's opinion. No need to get superior and snitty about it. And I object to characterizing it as a "mistake" to try to use a kind of design which has been working just fine for the last 3 years.

Why would anyone expect a lander like that to reenter in one piece?

Because they always used to, and it's productive and convenient for it to do so.

People, I don't think he's asking that the game be changed to suit him...

No, I am wishing that the game be changed to suit me. I'm just seeing if others agree.

And for you folks who are unhappy with me for valuing gameply over realism, consider this. That ship DOES land intact. It's just harder to do so than it would be if the adjustments I'm suggesting were made.

[mythbusters844]

Why not put fins at the very top of your lander? My capsule with science attached (playing career and can't EVA to transfer experiments yet) was flipping around during reentry with FAR but adding some small fins at the top of the capsule completely stabilized it.

[Capt. Hunt]

SAS should also help to stabilize it.

[Nansuchao]

IRL a similar ships will burn due to heating. You have two good/realistic solution to your problem:

- detach the capsule and re enter with just that, as suggested before;

- use the Engine to slow down before you hit the hard part of the atmosphere, so it will be easier to maintain stability.

[TMS]

SAS should also help to stabilize it.

Correct answer.

Spam with SAS and enough batteries to last re-entry.

[Keymaster89]

Correct answer.

Spam with SAS and enough batteries to last re-entry.

A sas ring will be useful, but i think that little fins will still be a necessity to go straight, or at least will help a lot on their own...

Yes. In my opinion, gameplay should trump realism, if the two conflict. And what's more, anyone who uses warp rather than fly multi-month missions in real time agrees with me, whether you'll admit it or not.

I am expressing one player's opinion. No need to get superior and snitty about it. And I object to characterizing it as a "mistake" to try to use a kind of design which has been working just fine for the last 3 years.

That was working on an incomplete game. Aerodinamic isn't science fiction, it's something that rockets HAVE to take into account. I think that you shoudn't grab and hold yourself into the past, that lander isn't aerodinamic at all... you should find a workarond like any player do, as adaptation and learning from mistakes is the core of this game.

You want to change the game into something that fits you, but i think you just stubborn on this thing and you're refusing that the game is changed to a point that your habits aren't just enough to accomplish what you need.

Time to restart from scratch i say...

[tater]

Why would anyone expect it to not be able to reenter in one piece? Sure we all know that reentry heating is a thing, but how is anyone supposed to know beforehand that their lander is going to flip over and potentially roast on return to Kerbin? With the current Science system, players are encouraged to bring back the instruments (and other parts, thanks to Recovery). Yet the aerodynamic and heating models make that difficult to accomplish and the game gives us no tools to predict that difficulty. The solution of "Move all Science to the pod and ditch the equipment before reentry" is not something a first-time-to-the-Mun player is likely to think of naturally and they won't realize their mistake until it's too late. I think this highlights a fault in game design and Vanamonde is right to point it out.

Sadly, I don't have any good solutions. As I see it, either include some tools for the player to make sense of the atmosphere and heating models, or simplify the models themselves. Both would require significant amounts of work and each would displease a segment of the playerbase.

You can remove science from the experiments, and place it in the capsule. The craft should reenter the way the craft should reenter. The test is to reenter, and see what happens. It flips, so you can either demonstrate that aerodynamically it should NOT flip, otherwise it is correct behavior.

Use a capsule.

[pellinor]

I'm not saying its unrealistic for the parts to behave this way with their current attributes. What I am saying is that it's undesireable from a gameplay standpoint for the player's landers to forcibly flip around twice during reentries, and those part attributes are arbitrary and can be changed. How much work it would take to fix this, I do not know. But I really don't like it.

People are saying just the opposite thing about rockets ("please make them fly nose first"). So in my opinion the problem is more about general control (and understanding) of aerodynamic behavior. So you don't change the physics of the game to keep old designs working, but provide people with the information and the tools to evolve their designs. I'm not asking for the lander to fly backwards, instead I want to tell it which way to fly.

Building the tools might be more about clever ideas than about writing code. So I see this happening in the player/modding community just as much as on squad's side. The aerodynamic model is very young so the tools to master it just need some time to emerge.

[basic.syntax]

Why not put fins at the very top of your lander? My capsule with science attached (playing career and can't EVA to transfer experiments yet) was flipping around during reentry with FAR but adding some small fins at the top of the capsule completely stabilized it.

I like this solution. That's working with the Aero system, instead of advocating to change it I've fought similar minor reentry battles with my own craft. Often SAS+reaction wheel+retrograde can track craft properly engines-down, all the way - give that a try. But the slightest maneuver off retrograde will (I think properly) lead to a flip. Additionally, with Claw's work-around/fixes, you can adjust the parachute deployment time, to reduce G-shock.

[DSKY]

How much work it would take to fix this, I do not know. But I really don't like it.

Depends on how much time you're willing to spend learning about aerodynamics, and learning how to use the CoM and CoL indicators in the VAB. That will probably take longer than it took you to write your post asking Squad to switch back to a highly flawed aerodynamics model, but less time than you will spend explaining why you think Squad should do that.

[tater]

What is even more funny is that it's already nearly impossible to have reentry actually be dangerous. I hit kerbin with a 20km periapsis doing nearly 12 km/s. Heatshield instantly evaporated... Then bare capsule happily survived. I did a direct reentry with a Mun lander from the Mun (had a probe core and fuel, but was earlier in career and had the small docking port). Anyway, direct reentry with ~20k periapsis set. No chutes. Landed it, but broke 1 of 3 legs.

[Starwaster]

It is my preference rather than an insistence, but I would like the mass/drag of the parts adjusted so that this doesn't happen.

No, I am wishing that the game be changed to suit me. I'm just seeing if others agree.

Ok, I've offered you an excellent solution already. The game is configurable so that your vessel can be made (nearly) flip proof without imposing on other people who don't want things your way.

Do what I suggested and make the changes at the designated menu. If you want I can see if it could be made into a Module Manager style solution.

[tater]

Yeah, this should be in mods, not suggestions for the core game.

For the core game, the question is is the aero system working right, PERIOD. If the craft is behaving as realistically as stock deals with things, then it should not change. Altering the aero to make certain, arbitrary crafts behave in an arbitrary way might screw up other crafts that otherwise made sense, and then won't, just so some ridiculous contraptions can among safe reentry (that should not be).

[KrazyKrl]

Add a drogue chute. Real reentry craft use them anyhow. And you rarely get absurd reentry speed and heating if you "stall" by aiming at least 10 degrees above prograde; this sacrifices airspeed for a slight reduction of decent speed (a win-win.)

But to even know if you need one; the VAB/SPH UI needs something to show you a directional heading when the CoL(should be center of pressure) indicator is turned on. Maybe as another click; something like "reentry mode" for the indicator which would show all stable orientations for the craft ("ghost" parts not attached to the root node are not included, for testing.) Of course, tweaking chutes as "deployed" in the VAB for testing would be required; they would be packed for launch though.

[Hcube]

Why don't you put a decoupler between the lander body and the capsule ??? this seems like the obvious solution to me...

Grab the science and store it in the capsule, and then ditch the lander before re-entry ! I shall point out that this is how a sample/experiment return is actually supposed to be done. oO can't believe some people expect their weirdly-shaped landers to re-enter perfectly.

Gameplay over realism ? Alright, but by taking the science in EVA and storing it in the capsule, you get a good gameplay element, and then the "correctly" modeled aerodynamic forces (that wouldn't let the whole thing come back alone) are not a problem anymore. here you go : gameplay and realism

[Master Tao]

I'd imagine that a more accurate display of aerodynamic forces would help here. Rather than warping physics to make crafts more stable, the game should display indicators letting you know whether the craft will be stable during reentry.

[Bug_]

I don't think this is the right sub-forum for this discussion. With all those fuel tanks and lander legs sticking out, that's what's going to happen. You need to design something to deal with that physics problem, not change the physics to make your design work..