WIP[1.05] Making Bricks Fly

[Sovek]

Spoiler

My continued quest for realism continues. Now I'm looking at making capsules fly. Heh. Under the new Aero model and FAR, (I use FAR), you can get capsules to fly. In fact even with limited RCS you can slow your decent rate so if you are coming over land... well you can keep from decending too fast and make it to water. But RCS is only good for about 2-3 minutes until I hit 40km and the force is just too much and I can no longer keep a 20 degree pitch.

Aside from a mod, is there any way of easily doing this and getting an offset CoM even if it invloves a little part clipping (like a small radial tank hidden inside a heatshield or something)

Greetings. This will be my first ever attempt at a mod, but its pretty easy, just some config files. The plan is changing the CoM towards the front capsules so that the aerodynamic forces will actually cause the pod to orient to 20-30 degree orientation allowing for controlled re-entry. This is planned to have only FAR support, Stock is not supported at all, if they work, they work.

Stuff to be done

• Stock 1.25m and 2.5m capsules
• HGR Soyuz-like capsules
• FASA Mercury, Gemini  and Apollo
• Tantares capsules
• Vens SRV 2 kerbal capsule
• Taurus HCV 3.75m capsule
• Near Future Capsules
• Correct License chosen (help on this would be appreciated)
• Possible CKAN support
• Possible integration with SETI re-balance. Contacted @Yemo, waiting on reply.

Stuff done

• Figure out how to make the correct MM configs so as to not cause incompatibility issues with SETI

Known Issues

• designed to work with stock heatshields or heatshields provided with the pack and the amount of ablator provided. Reducing the ablator may cause too much of a forward pitch.
• Testing requires that each change means I need to restart KSP, and even with all the mods from my 64 bit uninstalled and on a 32 bit fresh install, this takes time. So far there are probably along the lines of 10-15 capsules to work on.

Module Manager is REQUIRED, otherwise the mod will not work. Farrem Aerospace Research is also required for support. I will not provide support for the stock aerodynamics model.

Some pics

Spoiler

 

I'll keep everyone posted as progress continues. Hopefully I can have the first stock capsules done tomorrow, but my Panthers are playing in the Superbowl tomorrow, so not likely.

Update Edit 1: MM Config figured out, testing will commence at getting capsules to hold a 20-30 degree AoA @30-20Km. Thanks to @GoSlash27 and @sebi.zzr for providing the information on adjusting the CoM on capsules.

Update Edit 2: Mk1 capsule just about done... 30 degrees is a tad aggressive so I've tuned it down from -.2 to -.15. Have yet to test it. Also have pics

Edited February 7, 2016 by Sovek
Update thread to reflect current developement.

[fourfa]

Clipping a part inside the capsule itself seems like the way - try the small radial mount ore tank.  Empty 0.125t, full 0.875t (more than the 0.75t radial RCS tank).  Nice thing is, you can zoom inside the capsule, right click on the tank, and dump its contents instantaneously if you need to adjust the CoM on the fly.  Or use a large offset mass in a service bay under the capsule if clipping into the capsule bugs you.  

Then just like Apollo, control your trajectory by rolling to adjust the CoM relative to flight path

[Sovek]

1 hour ago, fourfa said:

Clipping a part inside the capsule itself seems like the way - try the small radial mount ore tank.  Empty 0.125t, full 0.875t (more than the 0.75t radial RCS tank).  Nice thing is, you can zoom inside the capsule, right click on the tank, and dump its contents instantaneously if you need to adjust the CoM on the fly.  Or use a large offset mass in a service bay under the capsule if clipping into the capsule bugs you.  

Then just like Apollo, control your trajectory by rolling to adjust the CoM relative to flight path

Right now I'm experimenting with a small radial tank on the bottom of the capsule underneath the HS... the first test did not offer much in the way of lift...

[MoonMan22]

12 hours ago, Sovek said:

Right now I'm experimenting with a small radial tank on the bottom of the capsule underneath the HS... the first test did not offer much in the way of lift...

This is a really interesting idea and if you get it to work please share. Just make sure what ever you use to offset the mass is completely hidden(clipped) inside the Command pod, otherwise it will affect the aerodynamic model.

 

goodluck!

[sebi.zzr]

I'm not FAR expert,but stock offers you some offset parameters:

@ = x,y,z
CoPOffset = 0.0, 0.0, 0.0  //center of pressure (default it's applied at the CoM)
CoLOffset = 0.0, 0.0, 0.0  //center of lift
CoMOffset = 0.0, 0.0, 0.0  //center of mass

or maybe you could add some lifting surface to pods:

dragModelType = none
MODULE
{
 name = ModuleLiftingSurface
 useInternalDragModel = True
 deflectionLiftCoeff = 0.47 // 5= 16,5m^2
 dragAtMaxAoA = 0.4
 dragAtMinAoA = 0.1
}

 

Edited February 6, 2016 by sebi.zzr

[GoSlash27]

Sovek,

 You can go into the .cfg file and add the following line:

CoMOffset = x.x, y.y, z.z

"x" should be the vertical offset in meters (positive toward the pilot's head)

"x" is the lateral offset (positive toward the pilot's right)

"y" should be the longitudinal offset (positive toward the front)

"y" is the longitudinal offset (positive toward the front)

"z" should be the lateral offset (positive towards the pilot's right)

"z" is the vertical offset (positive toward the pilot's bottom)

I'm not certain I have the axes and directions right. I'll try it out to verify.

*EDIT*

Here's the results:

Best,

-Slashy

Edited February 6, 2016 by GoSlash27

[Sovek]

6 hours ago, MoonMan22 said:

This is a really interesting idea and if you get it to work please share. Just make sure what ever you use to offset the mass is completely hidden(clipped) inside the Command pod, otherwise it will affect the aerodynamic model.

 

goodluck!

Didn't really work... even adding .6t to a 3t pod, it only provided a 10 degree pitch, not the 20 degree I was looking for.

This may become my first ever "mod" where I take every pod in my install (which is most of them) and add MM Config patches for them, and possibly work with @Yemo about releasing them as part of his mod.

[MoonMan22]

22 minutes ago, Sovek said:

Didn't really work... even adding .6t to a 3t pod, it only provided a 10 degree pitch, not the 20 degree I was looking for.

This may become my first ever "mod" where I take every pod in my install (which is most of them) and add MM Config patches for them, and possibly work with @Yemo about releasing them as part of his mod.

I see. Well that's a great idea and you should pursue it, many of us would love to have a mod that allowed the control through re-entry Apollo style.

[Sovek]

3 minutes ago, MoonMan22 said:

I see. Well that's a great idea and you should pursue it, many of us would love to have a mod that allowed the control through re-entry Apollo style.

Already on it. Message was sent to Yemo about including it with SETI Rebalance (as it took out the reaction wheels) and asked mods to move this thread as it will become the discussion and update thread of making it happen. I agree that its high time something like this came along.

[MoonMan22]

3 minutes ago, Sovek said:

Already on it. Message was sent to Yemo about including it with SETI Rebalance (as it took out the reaction wheels) and asked mods to move this thread as it will become the discussion and update thread of making it happen. I agree that its high time something like this came along.

Awesome keep us posted!

[Sovek]

Ok, I THINK this should do it, but I have a glancing knowledge on ModuleManager.

@PART[mk1pod]:AFTER[SETIrebalance]
{
	CoMOffset = 0.0, 0.5, 0.0  //center of mass
}

This value is just thrown in without any actual testing. Testing now to verify it works.

[Sovek]

Progress continues with the good old Mk1 pod. So far it flies, just not very well... Its a brick after all.

Pics included.

[Kerbal01]

Any plans to add the capsules from SSTU Labs by @Shadowmage?

[Sovek]

17 minutes ago, DarthVader said:

Any plans to add the capsules from SSTU Labs by @Shadowmage?

I can, once it enters full release. From the looks of it though its still a WIP, so things could change that would break the mod. I deff like the look of it though.

[GoSlash27]

I've been playing with this some, and thus far have mixed results.

 A stock Mk1 capsule takes about the right attitude with a mass offset of .3m, but this makes it way off- balance during launch. It's also way more offset than should be needed.

Also, the canted angle doesn't seem to affect the flight path. This may require a change in how it generates drag and lift in order to make it do what you want.

A little resource that may help:

http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19690020179.pdf

Best,
-Slashy

Edited February 7, 2016 by GoSlash27

[Sovek]

34 minutes ago, GoSlash27 said:

I've been playing with this some, and thus far have mixed results.

 A stock Mk1 capsule takes about the right attitude with a mass offset of .3m, but this makes it way off- balance during launch. It's also way more offset than should be needed.

Also, the canted angle doesn't seem to affect the flight path. This may require a change in how it generates drag and lift in order to make it do what you want.

A little resource that may help:

http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19690020179.pdf

Best,
-Slashy

.3 I can see going almost face first. .2 had a 30-35 degree angle of attack, it did provide a little lift. I don't know about stock, but FAR provided a lift of 5kn... not much. The Cl: IS low compared to the data gathered by NASA in their tests, but then again, they were going MUCH faster. I suspect this mod would be better on 3+ scaled systems, and really only useful on returns from munar or interplanetary missions.

That said, I'll look into adding some lifting surface for the Heatshields, I dunno if FAR handles that or not, I doubt it.

Edit: Looking over more data from NASA it appears that the Cd: is a tad high as well. And the L:D is way higher than what NASA recorded by about 3 times as much.. I'll run some tests with the stock equivalent of the Apollo CM to see if that goes any better... Tomorrow. I'm unsure if this is a result of the capsule being too draggy or not enough lift provided.

Edited February 7, 2016 by Sovek

[GoSlash27]

17 minutes ago, Sovek said:

.3 I can see going almost face first. .2 had a 30-35 degree angle of attack, it did provide a little lift. I don't know about stock, but FAR provided a lift of 5kn... not much. The Cl: IS low compared to the data gathered by NASA in their tests, but then again, they were going MUCH faster. I suspect this mod would be better on 3+ scaled systems, and really only useful on returns from munar or interplanetary missions.

That said, I'll look into adding some lifting surface for the Heatshields, I dunno if FAR handles that or not, I doubt it.

Sovek,
 I was conducting my tests in stock. .3m gave me about 15° of pitch.

This does raise another potential problem; it apparently doesn't behave the same way in stock as it does in FAR. Also, no doubt, it won't behave the same way with a heat shield as it does without, or with changes to the 'chutes.

 

Best,
-Slashy

Edited February 7, 2016 by GoSlash27

[Sovek]

 

7 hours ago, GoSlash27 said:

Sovek,
 I was conducting my tests in stock. .3m gave me about 15° of pitch.

This does raise another potential problem; it apparently doesn't behave the same way in stock as it does in FAR. Also, no doubt, it won't behave the same way with a heat shield as it does without, or with changes to the 'chutes.

 

Best,
-Slashy

On 2/5/2016 at 5:50 PM, Sovek said:

Module Manager is REQUIRED, otherwise the mod will not work. Farrem Aerospace Research is also required for support. I will not provide support for the stock aerodynamics model.

You do make a good point, it would be nice if there was a plugin that allowed you to modify the CoM via the editor menu but that is not something I'm capable of doing. I'll conduct some tests on the 2.5m pod to see what happens.... Also, it looks like I could stand to make some changes to RealHeat on making re-entry a tad... challenging, right now I'll loose like 50 ablator on a 2.5m heat shield... Meanwhile in stock (with 3x scale) I'm loosing about 130 on the 1.25m HS

Edited February 8, 2016 by Sovek

[Yemo]

Very interesting idea!

 

@GoSlash27 already mentioned two major problems:

1. Difference between stock and FAR
2. Non-reentry behaviour

ad 1: Craft that work in FAR should work in stock, though not always the other way around.

ad 2: The non-reentry behaviour is a huge problem, not only on ascent but also during maneuvers in space. This is compounded when mech jeb is used, which really dislikes asymmetric CoMs. It is also a problem for support, since it is a very unexpected behaviour even more than the always present "why can't I collect mystery goo?" with SETI-BalanceMod.

 

I'm no expert on how FAR works, but since the concept is focused on being used with FAR, would it be possible to "shadow-edit" the aero-properties of the capsules instead of the CoM offset? That would at least restrict problem 2 to atmospheric flight and would not affect maneuvers in space and for bodies without atmosphere. Unfortunately I have zero experience with tweaking FAR internals.

Another option would be to somehow utilize RealChutes to simulate an angled descent, like an invisible offset drogue chute or something along those lines, with the right settings, that could restrict the effect to aero descents or even kerbin descents specifically.