Having some trouble with a stock science module.

[Himynameisjake]

I have been looking to build a stock science module for a lander, centered around a Science Jr. with clampotrons on either end and all the other science experiments (and totally willing to add a bit of superfluous utility stuff like batteries, antenna, and solar panels to balance) mounted radially. The problem is vertically balancing the load. I have found ways to balance weight, and I have found ways to balance drag, but I cannot seem to balance both. I was wondering if anyone else had taken a stab at this (or something similar). I would like to keep it as light as possible, but I fear I might just end up throwing more parts on it than it is worth. Below is a list of things I'd consider putting on it:

NEED (just one of each):

Other things I'd like to keep as little as possible to balance (please excuse the hackjob edit):

I would also be willing to add a (small as possible) radially mountable counterweight like a light or RCS (could disable to maintain weight balance) tank or something. Any help would be great, I'm kind of at wit's end over here.

Edited February 17, 2014 by Himynameisjake

[Rodyle]

Hrm... Trying some things out right now. Mind if I use girder segments etc as well? Also: how much of an issue is the drag, really? I can understand the weight, but since they'll be attached to a larger spacecraft, does the drag really matter?

Edited February 17, 2014 by Rodyle

[Himynameisjake]

I'd like to keep the weight down as much as possible, but if that is what it takes (or structural panels), then I would consider it. Drag is a pretty significant issue, because I am trying to build as small of a craft as possible that would work universally for a grand tour (so it would have to deal with Duna, Laythe, and *shudders* Eve's atmosphere.

Alternatively, if anyone can think of a way to throw some structural panels on the thing to make a stock partial fairing setup (I would still have to be able to get data from the parts in an EVA), that would work too.

Edited February 17, 2014 by Himynameisjake

[Rodyle]

The standard aerodynamic model is, as far as I know, not good enough that constructing a fairing would keep the drag uniform. IIRC: it just takes the drag coefficient for each part and applies it to craft, even if it would be shielded from the wind. So, yeah. I don't really think it's possible to perfectly balance the drag and the centre of mass while using one of each part.

[Himynameisjake]

http://www.sendspace.com/file/wytzkx

This is about as good as it's going to get I think, which realistically is probably way better than I need it to be as far as balance goes. Thanks Rodyle

[technion]

The nose cone in particular is a huge pain and I generally just "don't bother". You can't place it anywhere but on the front, and I've usually got a clamp or a parachute sitting there.

The general experimental parts such as thermometers all have the same mass. So you can radially place a thermometer opposite a barometer for example, and it will be balanced. The goo cannisters, I usually suggest packing two, even if you only want one, just to deal with symmetry.

I don't have a better picture from it here, but I've recently restarted .23 career mode and my Duna lander sounded like exactly what you're describing.

Look at the top section. Basically, underneath the command module, which doesn't necessarily need to be able to separate like mine, there's a science jr with two radially mounted tanks. Each of them has a 47-8S engine underneath, and radially mounted science components. There is a clamp under the science jr.

This lander was capable of managing a Duna land and return, and includes solar panels and battery packs.

Edit: Despite what I said above, there is a nosecone on this image. It's the only thing that blew up during my descent (I play with DRE) and I haven't used it since.

Edited February 18, 2014 by technion

[Geschosskopf]

I have been looking to build a stock science module for a lander, centered around a Science Jr. with clampotrons on either end and all the other science experiments (and totally willing to add a bit of superfluous utility stuff like batteries, antenna, and solar panels to balance) mounted radially. The problem is vertically balancing the load. I have found ways to balance weight, and I have found ways to balance drag, but I cannot seem to balance both

To toot my own horn, I have to recommend my tutorial on MISSION PLANNING and SHIP DESIGN FOR SCIENCE!

The bottom line is that if you're going to return the science instead of transmitting it, then you need 4x Science Jr. bays, 4x Goos, and 1x of every other instrument you have available. So what I do is build a take a small box girder oriented vertically and radially attach the 4x Science Jrs to it, then 1 goo on each bay. Put a capsule on top, an SAS on the bottom. Put the other small instruments on wherever you like because they don't weigh or drag enough to matter. Group them around the capsule hatch, stick them all on the side of the Jr bay closest to the hatch, whatever. Put some parachutes on it so this whole assembly can come down safely. Presto, you have a science pod for suborbital and orbital use.

Now put the small radial decouplers on the sides of the Jr bays and hang fuel tanks, engines, and landing gear off them as required by where you're going. Now you have a lander. When you get back to Kerbin, do the de-orbit burn to loose the tanks, engines, and gear so the same chutes can bring the science parts down.

Also, rig ALL science parts to a single action group so they all go off at once. That's really helpful when doing science while hanging from your parachute.

[Claw]

Hrm... Trying some things out right now. Mind if I use girder segments etc as well? Also: how much of an issue is the drag, really? I can understand the weight, but since they'll be attached to a larger spacecraft, does the drag really matter?

KSP's drag model (in 0.23 anyway) is pretty basic. Usually slightly asymmetric drag will be much less of a factor than asymmetric mass for small craft. Asymmetric mass will haunt you for the entire voyage. Asymmetric drag from science parts will likely be unnoticeable when launching from Kerbin. I'm sure you can prove me wrong here, but I'm talking about basic designs like you describe. Not attaching multiple copies of everything to one side. Even at that, you'll suffer more from the asymmetric CoM.

[Himynameisjake]

While that's pretty neat info, it's not very usable for a Grand Tour. The Delta-V for that would just be gross. I am considering just going with the nosecone idea, though I really do like having clampotrons on both end. neat guide though!

Edited February 18, 2014 by Himynameisjake

[Geschosskopf]

While that's pretty neat info, it's not very usable for a Grand Tour. The Delta-V for that would just be gross. I am considering just going with the nosecone idea, though I really do like having clampotrons on both end. neat guide though!

You didn't mention a Grand Tour in your 1st post.

But a Grand Tour isn't a very practical way to do science in 0.23 now that they've nerfed transmitting data. And goos and bays only work once per mission, transmitted or not, unless you have a Mobile Lab to rearm them. So, for a Grand Tour, you either need a full set of science parts for every place you're going, or you need a Mobile Lab to continually rearm a single set of science parts after you've removed the data either by transmitting or storing in a capsule or the Mobile Lab itself. Either way, forget doing it small-scale.

[Himynameisjake]

Sorry, didn't realize that was in my second post not my first. Anyways, yeah, I'm doing the MSL, it's pretty effective, and I'll be storing all data and cleaning as I go.

[Geschosskopf]

Sorry, didn't realize that was in my second post not my first. Anyways, yeah, I'm doing the MSL, it's pretty effective, and I'll be storing all data and cleaning as I go.

Well, in that case, you just need a lander with a full set of science parts. While it's docked to the MSL, you can use its science parts in orbit, clean them out, and use them again on the surface. So it's just a matter of designing the lander with enough TWR and delta-V to get down, back up, and rendezvous at any place within reason. If you exclude landing on Eve and Tylo, IIRC the TWR is defined by the Moho landing and the delta-V by the Laythe ascent. And you also need enough chutes for Duna.

If you're going to return all the data, then you need 4x bays and 4x goos on the lander, as described in my guide. If you're going to transmit instead, then you only need 2 each before you hit the transmission cap.

[Himynameisjake]

I will probably just do 1 of each, get the Grand Tour out of the way and then come back when there's reason to. I will get the "high in orbit" and "low orbit" ones and clean those, and then do a surface run. There's still plenty to interest me for return missions. As for the bigger planets and moons, I'm doing adapters to my base craft to get them all

[Dave Kerbin]

You might draw some inspiration from a moon probe I built that was relatively successful at balancing a single goo container.

Overall though you really need to think about where you are going. Most bodies don't have an atmosphere so the barometer and sensor nose cone are useless. On bodies that do have an atmosphere you are faced with a small issue - you need to collect the high atmosphere and low atmosphere readings within a short time span and without a safe period to exit the capsule to collect anything.

For your planning I would make these suggestions:

• Determine if you are doing a manned or unmanned mission. If it's manned then apart from the Science Jr and Goo you only need one set of the vacuum instruments and 2 of the atmospheric ones.
  
• If it's manned consider how you might detach Science Jr and Goo containers after they have been used (and the data collected) to save weight
  
• One way probes can also benefit from discarding used up Science Jr and Goo containers.
  
• If you are having issues consider a pair stock science module - the standardized module contains all the experiments needed for 2 biomes. This makes it easier to balance.
  
• Consider seperate stock modules for atmosphere and vacuum.
  

[Himynameisjake]

Dave,

While I appreciate the idea of unmanned, I more like the challenge and feel of a Grand Tour with Jeb along for the ride.

As for the atmospheric vs. vacuum modules, I considered it, however, I want to keep the part count down, and one easy way to do that is just having one lander, even if it means adding a little mass.

Now adding a little mass is one thing, but doubling it makes getting off Tylo and Laythe a pain, so I don't think I'll go for the pair module. Eve would be a good place for this, because I plan on leaving the science module (and really everything but a chair, probe for control surface and SAS, and small amount of thrust behind for that.

Definitely some food for thought all the same, and I really like your probe design