How do I determine if a part is shielded?

[Laie]

How can I tell if a part is safely inside a cargo bay?

It's easy to find out with parts that "cannot deploy while stowed" -- and from experience with them, I know that the game has it's own ideas about if or when a part is shielded. That's why I'm looking for a method to check it for everything.

[Starchaser]

Not to be flippant, but in reality parts that can affect aerodynamics are tested in a wind tunnel. Since we lack that in KSP, test launch on a sub-orbital hop and see how it re-enters. Revert the flight so you can say it was 'simulated.'

 

[Geschosskopf]

1 hour ago, Laie said:

How can I tell if a part is safely inside a cargo bay?

Only by whether it explodes or not on re-entry.  This is something the game has been consistently inconsistent about ever since re-entry heating became a thing.  It seems that every update has solved one problem only to introduce another.  There has been a general improvement over time, in that bizarreness happens a lot less often now than before, but it still happens.

One thing I've noticed, though, is that cargo bays seem to have been set up with the assumption that they'd only be opened once per flight, and that nothing in them would ever be deployed.  IOW, shuttle goes to orbit, bay opens, probe comes out, then probe deploys its solar panels and antennae once clear of the shuttle.  If you do things that way, all is (usually) OK, although sometimes things get hot inside the bay (or the bay itself gets hot) for no apparent reason.

If, however, you're using the cargo bay as a reusable fairing, the game seems to get confused about the deployed/retracted state of parts inside the bay.  For example, airplane flies to Point A, lands, opens bay, extends antennae/instruments for science, retracts everything, closes bay, flies to Point B, repeat.  Or it will now think the wing parts attached on the outside of the bay are now inside the bay, so won't let them produce lift.  So it's a good idea not to do this sort of thing.

The same sort of thing can happen with heat shields.  Say you have a 1.25m stack of instruments on top of a 2.5m heatshield to give it extra-wide protection.  If you deploy an antenna on the 1.25m stack while in space to send some orbital science, then retract it and land, the game will still sometimes treat the antenna as deployed and burn it up.

 

[Laie]

9 hours ago, Geschosskopf said:

(lots)

 

My takeaway message is that the only way to find out is looking for friction heat, and that it may change any time I open and close the fairing.

The first was what I was afraid of, the latter is news to me, and bad news at that. Thanks for warning me.

[Geschosskopf]

33 minutes ago, Laie said:

My takeaway message is that the only way to find out is looking for friction heat, and that it may change any time I open and close the fairing.

The first was what I was afraid of, the latter is news to me, and bad news at that. Thanks for warning me.

Well, such heat weirdness is a lot less common than it was at first, and it's fairly easy to deal with.  Just observe the rule of "it's not cheating if I'm only doing it to work around an obvious bug."  Get everything squared away and secured for re-entry, then quicksave.  Then re-enter or otherwise subject the cargo bay to heat and/or high airspeed.  If something burns up that logically should not, load the quicksave, open the cheat menu to disable heating, then fly it again.  Once through the danger zone, turn heat back on.

The bigger problem is the loss of lift from wings that are radially attached on the outside of cargo bays.  Again, this doesn't happen as much as it used to, but the worst part is that when it does happen, it usually only affects 1 of the 2 wings, so now the plane wants to roll over.  You can see this by toggling the aero arrow markers.  Usually, the only way to solve this is to open and close the cargo bay repeatedly, and it often ends up that you have to leave the bay open to have lift on both sides.  I've heard it's possible to fix this by editing your save file but I've never done that myself.

Bottom line is, I've pretty much given up on using cargo bays as reusable fairings for instruments and stuff that will remain in the plane and be used repeatedly.  It's safer to just stick everything on the outside, or use Universal Storage.

[Laie]

@Geschosskopf: my main concern is not as much things burning up, but drag per se. I noticed how much faster my planes can go if all the small stuff is stowed. Even on a Joolian round-trip that effect is absolutely worth the extra weight of a cargo bay just to sink in a few pieces. Provided it works... only that sometimes it doesn't, which is why I was asking this question.

[AeroGav]

The best way to determine if a part is shielded or not is to press ALT + F12,  go to the Physics Tab,  check the "Show Aero Data in Action Menus" tickbox.

Right click on the part while your craft spawns on the runway,  and  get into a high speed taxy.  

The right click menu will show "Shielded True:False".   Since the 1.3 update I've found it hardly ever shows "Shielded : True",  yet the part can have zero drag.   So the drag value is what the OP should be paying attention to, especially given that's his reason for using the cargo bay.

Re:entry heat is harder to test.   You'd have to use the "Set orbit" cheat then get it re-entering to be certain.    I've found that the game is more lenient with heating than drag however.   

Parts which are attached inside a cargo bay, but offset outside of them (custom cockpits for 2.5m spaceplanes) get drag, but seldom have heat.