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Devnote Tuesday: It’s All In The Details


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Why not make the video with 90% in-game footage. Like how Nassault does it. If in-game visuals are not up to scratch, then improve them until they are.
Principally because even if the game *did* have high-quality graphics, it doesn't let the player control the Kerbal's movements in enough detail.
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Center of drag does not make sense as a point separated from canter of lift, there should be a single point, called "Aerodynamic Center" or whatever you want to call it.

To give you a simple example of the reason behind that, assume you have a small angle of attack while building on the SPH.

Part of the lift effects of your wings will be pulling the plane back, part of the drag will be pulling it down, what is lift and what is drag there?

You cannot simply assume that all forces pulling the craft back are drag and up are lift, nor can you do that referencing the cockpit position.

Both forces are acting together on the craft, that is what gives the craft it's flight characteristics.

I understand what you mean, however in KSP it would be worthwhile to separate the two according to the referencing cockpit/control module position (as is already the case for lift atm anyway). The problems I've been experiencing, for instance, involve bottom heavy single stage return launch vehicles. I'll give you an example of a ballistic flight trajectory without wings and with:

Without wings

- In the VAB, the CoM is visible but the CoL is not. No wings, control surface or other lifting surfaces are present.

- During flight, fuel typically drains from top to bottom, shifting the CoM down to a point where it goes below the invisible center of drag (CoD). This causes the craft to flip around (engines prograde), great for landing, not so much for ascending or keeping your control module prograde.

With wings

- In the VAB, the CoM is always above the CoL, both fully fueled and empty (and in between).

- During flight however, scenarios arise where the craft flips around like described above. I can only assume this is due to CoM shifting behind the CoD.

If the CoD relative to cockpit/control module position was visible in the SPH/VAB, I could prevent the craft from flipping over by making sure the CoM would never drop down below the CoD. I realise that these conditions only occur with specific craft designs, but nevertheless, it would be great to have a CoD display. As lift is a force typicallytm perpendicular to and drag opposite to prograde motion, in my humble opinion, an "Aerodynamic center" does not help overcome these designs issues, however a separate "Center of Drag" display would...

Edited by Yakuzi
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With all the focus on the camera, there was something else I noticed: a thought about hiring Kerbals.

Now, perhaps you are still working on this and have plans for it, but I've always had an issue with reputation not really having a purpose. I mean, you can turn it into other currencies, and it is (presumably) needed to get better contracts, but there is no way to "spend" reputation directly, per se.

It might be nice if say either, 1) lower reputation made the cost of any kerbals you buy go up (so cost is a combination of # of kerbals on your roster and reputation), OR 2) it actually costs you reputation to hire kerbals as well, and like money, the more reputation the more kerbals you have.

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I understand what you mean, however in KSP it would be worthwhile to separate the two according to the referencing cockpit/control module position (as is already the case for lift atm anyway). The problems I've been experiencing, for instance, involve bottom heavy single stage return launch vehicles. I'll give you an example of a ballistic flight trajectory without wings and with:

Without wings

- In the VAB, the CoM is visible but the CoL is not. No wings, control surface or other lifting surfaces are present.

- During flight, fuel typically drains from top to bottom, shifting the CoM down to a point where it goes below the invisible center of drag (CoD). This causes the craft to flip around (engines prograde), great for landing, not so much for ascending or keeping your control module prograde.

With wings

- In the VAB, the CoM is always above the CoM, both fully fueled and empty (and in between).

- During flight however, scenarios arise where the craft flips around like described above. I can only assume this is due to CoM shifting behind the CoD.

If the CoD relative to cockpit/control module position was visible in the SPH/VAB, I could prevent the craft from flipping over by making sure the CoM would never drop down below the CoD. I realise that these conditions only occur with specific craft designs, but nevertheless, it would be great to have a CoD display. As lift is a force typicallytm perpendicular to and drag opposite to prograde motion, in my humble opinion, an "Aerodynamic center" does not help overcome these designs issues, however a separate "Center of Drag" display would...

I understand what you are worried about, but a COD is not the solution.

First of all, remember that AC takes into account both effects at once, on current stock KSP the drag is always on the center of mass.

Secondly, you cannot simply make the airstream inline with the cockpit, that would bring two very big issues, what if your cockpit does not have 0 degrees of AoA relative to your craft? And how are you going to know what happens to the AC under different conditions?

And third, simply because you can do it for a very specific case, does not mean it gives you any sensible information, you forgot that wings can have built-in AoA, your craft is free to have any shape, and that lift and drag are not as much two independent vectors in space without direct correlation as the wording makes it sound:

airfoil.gif

As I mentioned on the previous post, you could consider forces on the Y axis as lift, and on the X axis as drag, but that loses sense on a dynamic environment.

If you want to calculate lift and drag positions you would have to pick a single frame during your flight and measure it, which wouldn't be that useful either.

Now to how an actual AC is more important to your concerns than you think:

COL on the current VAB is not shown because of how the current stock KSP works, drag is inline with COM and lift is only generated by wings.

"Center of drag" effects only happen if you are using FAR or NEAR, on the case of FAR the stability derivatives will tell you if there is something wrong (and we will get some sort of analysis on 1.0).

What causes the craft to flip around is not drag, but the whole aerodynamics effect, you have your AC in front of your COM, not drag.

If it's still confusing, on supersonic the drag is mostly on the tip of the airplane, and the lift moves back, so you have your "center of drag" really in front of your center of mass on most cases but that does not make your craft unstable.

These scenarios where the craft flips are certainly either related to roll or yaw instability, not pitch, having your AC behind your COM ensures dynamic pitch stability (If you use FAR, check Mw), but if you have some sideslip angle and not enough tail to counter it, or too much dihedral effect, when you pitch these effects can flip your craft sideways or on a corkscrew and then flip you backwards.

Stall can also be a cause.

AC is exactly what you want to know what is going to help with your flight characteristics, it makes sense, and it's how it actually works, I believe that a COD would cause more confusion than solve on any other case.

Take rockets for instance, if you have tail fins on the bottom that does not bring your drag to the bottom, but your lift stabilizes it, you would still see the drag above the COM and that would not make any actual sense.

Also, there shouldn't be a COL either, as I mentioned previously, just an AC.

If you want to understand it a bit better I recommend you to take a look on how FAR does it, take a look at the stability derivatives and at how the COL point is represented (It's actually an AC).

If you already use it, what I just said should be a bit easier to understand now (but I believe you don't since you mentioned the nonexistent COL without wings).

Edited by tetryds
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so when all those people do start playing they will be accustomed to a level of detail and visual fidelity that is not present in the game... cue disappointment.

Why not make the video with 90% in-game footage. Like how Nassault does it. If in-game visuals are not up to scratch, then improve them until they are.

why use resources on a task with such limited return on investment???

I totally agree with this. I think in this age of gaming we are tired of pre rendered scenes. It tells you nothing about what the game is like.

In fact it gives you a false image of how things are. It leads only to disappointment.

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I would presume that they don't think the return is poor enough to justify stopping. Or more accurately, it's strong enough to keep it up.

I don't work in Marketing, so I'll defer to those who have a closer relationship to people who do.

Wasn't some/most of the art department hired pretty much specifically for making these videos?

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Comic sans snip

Thanks for that explanation, that does clear things up quite a bit. I was talking about stock indeed, in FAR I don't have these problems (though have different designs). I had no idea the current stock aerodynamic model dynamically incorporates changes in CoL and CoD for supersonic speeds. Also, I forgot that CoM = CoD in stock, but as far as I recall, I am indeed getting pitch instability (defo no yaw or roll), so that shouldn't be possible according to what you said above. It might be an error on my side, let me check if I still have that craft and see if I can find the culprit. Thanks again for the in-depth reply tetryds!

NB: in stock you can have a CoL without wings as PJ's MK2 parts generate lift

Edited by Yakuzi
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Will there be an option to disable the camera shake? Not that its a bad thing its just in third person with camera shake can be uncomfortable for some people to play with. I know for me I get kinda motion sick with to much camera shake and normally disable that feature in any game that has it.

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Will there be an option to disable the camera shake? Not that its a bad thing its just in third person with camera shake can be uncomfortable for some people to play with. I know for me I get kinda motion sick with to much camera shake and normally disable that feature in any game that has it.

Not only a disable option, but an actual multiplier slider, which will range from 0 to even bigger than one, as Harv said on page4.

@Yakuzi: No problem, it's possible that even though both FULL and EMPTY states are fine, due to how fuel flow logic works, there is a point in between where your COL goes past in front of the COM.

I saw a dev blog stating that on the next update, jet engines will consume fuel evenly on the craft so this issue will not exist anymore :)

Also, if you have more doubts you can just PM me, I would be glad to help.

Edited by tetryds
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Will there be an option to disable the camera shake? Not that its a bad thing its just in third person with camera shake can be uncomfortable for some people to play with. I know for me I get kinda motion sick with to much camera shake and normally disable that feature in any game that has it.

Harvester commented earlier in the thread that it will be both disableable and adjustable in intensity.

Edit: Ninja'd!

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And yeah, no biggie if the rest of sci-fi is the same. But still, it would be a nice little touch, hearing only the sounds being made by the active vessel.

In my head-cannon, all reasonably Sci-Fi vessels, KSP included, have built in Hi-Fi systems that *emulate* the sounds of nearby ships/explosions. It's the high tech version of a collision warning, letting you know that there is a ship or whatever nearby. It takes advantage of our "free" 3D awareness system - our ears.

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<b>Felipe (HarvesteR): </b><ul><li>Added TrackIR support to all game views, plus independent toggles for each of those in game settings</li></ul>

Can we get a togglable "always 1st person" mode. That and RPM would be very interesting.

<b>Felipe (HarvesteR): </b><ul><li>Part test contracts now round their altitude and speed envelopes to much more sane values.</li></ul>

One step closer to me caring about career.

<b>Felipe (HarvesteR): </b>The cost of hiring more crews increases for each additional crew member in your active roster, that is, hiring your 30th Kerbal is much more expensive than hiring your 5th one.

If this is how you pay people at Squad, you're doing it wrong.

<b>Felipe (HarvesteR): </b>I’m adding a camera wobble system, to allow cameras to shake and vibrate in response to external forces.

Sounds good to me.

<b>Max (Maxmaps): </b>Mind you, you have to look past the actual behemoth systems that still had to be made for 1.0, aero is big. Really, really big.

Well, it's a good thing you decided to add really, really big systems right as you're releasing 1.0. In the words of video games: Your choices will have consequences.

Edited by klgraham1013
grammar
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Harvester:

The wobblecam sounds interesting.

What's TrackIR?

And I'm trying to work out what exactly is the April Fool in there, or is it just the April Foolderators on the forum?

Maxmaps:

Space is big. Really, really big.

Kasper:

So you had to spam-delete blog-spam from a blog-spamming spam-bot. :P

Edited by TheMoonRover
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so when all those people do start playing they will be accustomed to a level of detail and visual fidelity that is not present in the game... cue disappointment.

Why not make the video with 90% in-game footage. Like how Nassault does it. If in-game visuals are not up to scratch, then improve them until they are.

why use resources on a task with such limited return on investment???

So much this.

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