Spaceplane questions

[dire]

Hi all, I've run a few SSTO planes now and it occurs to me that I can probably do better, but I don't have the information I need yet. If anyone knows this stuff it'd be a great help. For SCIENCE! I'm using the latest Steam version of the game on PC (V. 1.1.3 I guess?) as I understand that makes a big difference to spaceplanes.

1) Would hacking the config file or something for KER to convince it to run on this version actually work, or would it just break stuff? Has anyone tried this? I would like to know my net delta-v but I'm too lazy to calculate it myself.

2) I've read that Kerbin's atmosphere is stacked in layers with hard boundaries between the layers; does anyone know offhand what altitude the cutoff points are (aside from the 70km cutoff to space)? I've noticed that my air intake tends to drop smoothly when I monitor it over 10km, so I may not even be asking a meaningful question here.

3) Does it still count as a spaceplane if the payload is the entire fuselage including cockpit?

4) I've noticed the sonic/reentry effects are sensitive to the craft's profile, and that heating effects are also sensitive to the craft's profile, but I read that drag effects are simply a function of the craft's mass times some co-efficient. Is that still correct for this version?

5) I noticed the shock cone weighs twice as much as the ramp intake, and the inline intake seems to just be all-around better than the pre-cooler, is there some reason that the shock cone and precooler are better parts for a spaceplane?

[Gaarst]

1. Even though KER says it's not compatible with 1.1.3 when launching, it works just fine
2. Never heard about that
3. Does it take off horizontally? Does it go to space? If yes then it's a spaceplane
4. That was correct for KSP before 1.0. Now drag is (approximately) properly calculated, so try to make a craft that looks real and it should be fine, also keep a high AoA during reentry to handle reentry heating better
5. The shock cone takes air until further up than the ramp intake, very useful for any high altitude plane. Not sure if the precooler has any use beside esthetics.

[FancyMouse]

2. Atmosphere itself is just a scaled US standard atmosphere model with a 70km cutoff. But what you described sounds like the engine thrust cutoff - i.e. each jet engine has its own hard altitude limit of its operation. That's engine-specific.

4. Drag equation is always like that. The only difference between pre-1.0 and post-1.0 is that the drag coefficient was contant pre-1.0, but relevant to your craft shape and AoA post-1.0.

5. Not only about high altitude but also high speed, and drag consideration. There was excellent discussion about it:

I don't think anything has changed significantly since then, other than maybe shock cone mass increased for game balance (can't remember when it happened).

Edited July 21, 2016 by FancyMouse
snip wrong stuff as pointed below

[Snark]

1 hour ago, dire said:

3) Does it still count as a spaceplane if the payload is the entire fuselage including cockpit?

The word "count" confuses me-- that's a value judgment.  You take off how you like to take off.  "count" according to whom?

1 hour ago, dire said:

4) I've noticed the sonic/reentry effects are sensitive to the craft's profile, and that heating effects are also sensitive to the craft's profile, but I read that drag effects are simply a function of the craft's mass times some co-efficient. Is that still correct for this version?

No.  Mass is completely irrelevant to drag.  All that matters is the size/shape of the craft.

That's a new thing-- well, relatively new, anyway, it came in with the radically revised aerodynamics in KSP 1.0 over a year ago.

Before 1.0, size and shape didn't matter-- only mass did.

After 1.0, mass doesn't matter-- only size and shape does.  (And orientation relative to the airflow.)

15 minutes ago, FancyMouse said:

Drag equation is always like that. The only difference between pre-1.0 and post-1.0 is that the drag coefficient was contant pre-1.0, but relevant to your craft shape and AoA post-1.0.

This is not the case.  There's a big difference:  mass went from being the only determinant for drag, to being completely irrelevant.  A full fuel tank will have exactly the same drag as an empty one now.

 

[FancyMouse]

6 minutes ago, Snark said:

This is not the case.  There's a big difference:  mass went from being the only determinant for drag, to being completely irrelevant.  A full fuel tank will have exactly the same drag as an empty one now.

 

Oops I already realized it after I wrote it and I thought I deleted that section which apparently isn't the case... that's completely my bad! Thanks for pointing out!

[dire]

OK, I'm probably having a nub moment here but i can -not- figure out how to pull up a report telling me what my delta-v is from my hangar. I downloaded kerbal engineer, put it in my gamedata folder. I have parts that I can stick on my ship but they don't have context menus if I do. Supposedly I'm supposed to have a button somewhere?

The only thing I can think I did wrong is perhaps I downloaded "Kerbal Engineer" instead of KER and the addon doesn't do what I think it does.

[Zophos]

1 hour ago, dire said:

OK, I'm probably having a nub moment here but i can -not- figure out how to pull up a report telling me what my delta-v is from my hangar. I downloaded kerbal engineer, put it in my gamedata folder. I have parts that I can stick on my ship but they don't have context menus if I do. Supposedly I'm supposed to have a button somewhere?

The KER menus don't show up unless you have a control-capable part (capsule, cockpit, probe core) and a KER module on the craft.  There are two ways (that I know) to get a KER module: (1) place the KER part on the craft, or (2) under the KER settings, select "partless" instead of "career".  Option 2 makes all control-capable parts have a KER module, without installing a separate part on the craft.

So try putting the KER part on the ship.  If things are working properly, THEN you will get a KER button in the app launcher (that menu on the lower-right in the SPH). See the shot of my SPH below and note the KER button third from the left.

[dire]

Thanks for responding. In the screenshot I posted above, the part I moused over is currently on the plane and there is no KER menu in the app launcher. If that is not a KER part then I have the wrong addon installed. 

There's an open service bay semi-visible under the mouseover text, and the part is sort of visible inside it.

 

The KER menus don't show up unless you have a control-capable part (capsule, cockpit, probe core) and a KER module on the craft.  There are two ways (that I know) to get a KER module: (1) place the KER part on the craft, or (2) under the KER settings, select "partless" instead of "career".  Option 2 makes all control-capable parts have a KER module, without installing a separate part on the craft.

So try putting the KER part on the ship.  If things are working properly, THEN you will get a KER button in the app launcher (that menu on the lower-right in the SPH). See the shot of my SPH below and note the KER button third from the left.

Edited July 22, 2016 by dire