A not too scientific comparison of aero/new part performance in 1.5.x compared to older versions

[Vexillar]

So I thought, I wonder how much the new parts have changed in terms of performance?

To get a rough idea, I created a simple craft consisting of: Mk1 pod, Mk16 parachute, TR-18A or TD-12 decoupler and a Hammer booster.  Engaged SAS and launched straight up.

Here are the results:

KSP Version	Max. Altitude (m)	Max Speed (m/s)	Max G (G)
1.0.5	95,194	1,246	11.1
1.2.2	124,248	1,358	12.2
1.3	123,655	1,357	12.2
1.4.5 1	113,334	1,320	11.8
1.5.1 2	146,457	1,440	12.8

Note 1: Using TD-12 decoupler, 1kg lighter
Note 2: Using TD-12 and new version Mk1 Pod

Results are very consistent between 1.2.2 and 1.3, I guess the 1.0.5 is down to the old souposphere... though I now forget when the atmosphere was changed.

1.5.1 must be down to the new pod model being "slippier", as well as the lighter, smoother TD12 decoupler.

What surprises me is the 1.4.5 result.  I'd expected a slight "improvement" over 1.2.2/1.3.  Would the time of day (atmospheric temperature) have a significant effect?

[MR L A]

2 hours ago, Vexillar said:

Would the time of day (atmospheric temperature) have a significant effect?

No, KSP doesn't account for this afaik, and, again afaik, neither does FAR.

Interesting work though, now for all the other parts that have been changed

[Gaarst]

23 minutes ago, MR L A said:

No, KSP doesn't account for this afaik, and, again afaik, neither does FAR.

It actually does. Open up the AeroGUI in the cheats menu and you will see air temperature and density vary as the day progresses. I don't know how significant it would be in this experiment but it is definitely a thing (if you want to find out launch a spacecraft at noon and one at midnight and report your results).

[juanml82]

There are differences in the aero model in 1.5.1 vs the one in 1.4.5

I've tested a single (larger) spaceplane, which made it to orbit ok in 1.4.5 and in 1.5.1 it's possible for its nosecone to blow up due overheating - and it's not due the thermal model, the plane flies higher and faster on air breathing mode.

Not complaining.

[Tyko]

On 10/25/2018 at 3:25 AM, Vexillar said:

1.5.1 must be down to the new pod model being "slippier", as well as the lighter, smoother TD12 decoupler.

You don't need the decoupler for your test and you could encase the pod in a fairing to eliminate any differences in pod aerodynamics. Or just use a probe core and a locked fuel tank in a fairing for your payload. Anything that makes your craft "identical" will make your test a little less non-scientific

 

[Ultimate Steve]

And over here I remember that in my first ever mission, in 0.19, the exact same craft configuration would not make it anywhere near space!

[MR L A]

14 hours ago, juanml82 said:

There are differences in the aero model in 1.5.1 vs the one in 1.4.5

I've tested a single (larger) spaceplane, which made it to orbit ok in 1.4.5 and in 1.5.1 it's possible for its nosecone to blow up due overheating - and it's not due the thermal model, the plane flies higher and faster on air breathing mode.

Not complaining.

The change log mentions no alteration of aero; however, squad have confirmed that the part updates also effect their aerodynamic properties - so I’d imagine the reason your craft is flying differently is because of the parts it uses

[Aeroboi]

28 minutes ago, MR L A said:

The change log mentions no alteration of aero; however, squad have confirmed that the part updates also effect their aerodynamic properties - so I’d imagine the reason your craft is flying differently is because of the parts it uses

I'm gonna test this. I'm not sure how profoundly I'm gonna do this but if it turns out to be profound I'll post the findings. I did a lot of aerodynamic testing already in 1.5.1 for a project I'm working on so I already have things to use.

Furthermore I'm not very happy about these constant changes to aerodynamics. One universal sheet of physics laws across all the upcoming versions of KSP from now on.

@SQUAD Because, why not?

[MR L A]

2 minutes ago, Aeroboi said:

Furthermore I'm not very happy about these constant changes to aerodynamics.

Like I said, squad haven’t mentioned any aero changes for this update and the general consensus is they haven’t made any. 

As for not updating the KSP laws of physics, I couldn’t disagree more. If squad decides to implement more advanced aero properties like those in FAR or advanced orbital stuff like Principia, they’d be most welcome as they only open up more options for things like ground effects or halo orbits. Hell, even minor changes to aero probably should be made as the atmosphere is STILL quite soupy. 

I really don’t think Squad should worry about implementing such updates (which I doubt they would anyway) just because a couple of badly designed craft no longer work properly. 

[Aeroboi]

4 minutes ago, MR L A said:

Like I said, squad haven’t mentioned any aero changes for this update and the general consensus is they haven’t made any.

You don't understand me correctly.

44 minutes ago, MR L A said:

squad have confirmed that the part updates also effect their aerodynamic properties.....

While I should have mentioned it I consider "part updates" and "Aerodynamics properties" as a way to change aerodynamics. Why does Squad do this by changing a part aerodynamic properties without a clear reason? That would only be clear if the part itself changed in it's shape. 
A 1.25m circular decoupler remains a 1.25m circular decoupler, it's aerodynamics shouldn't change, so why is that then?

When I say I don't want aerodynamic changes then it is based on realism ironically. Realism in my view is that aerodynamics don't change. Something doesn't become more dynamic through gas or fluid or becomes lighter without changing it's shape.

14 minutes ago, MR L A said:

If squad decides to implement more advanced aero properties like those in FAR or advanced orbital stuff like Principia, they’d be most welcome as they only open up more options for things like ground effects or halo orbits. Hell, even minor changes to aero probably should be made as the atmosphere is STILL quite soupy.

But, I agree lol.

I said I'm not happy about these "constant" changes to aerodynamics. And again, that means part aerodynamic parameter updates also.
In a complete overhaul it will be a real aerodynamic update. When it changes all the bits you summarized and does it good like a typical flight sim does I will rejoice. Changing aerodynamics on a 1.25m gasket ring (= decoupler) is nonsensical to me and it fuels my my comment to stop all these minor and frequent changes to aerodynamics whether that is directly or via a part configuration on i.e. a decoupler.

[MR L A]

5 hours ago, Aeroboi said:

That would only be clear if the part itself changed in it's shape. 

This is exactly what has happened. 

They haven’t actually altered the parts aerodynamics other than by what the game generates automatically using the textures maps (or something like that - basically aero is calculated partially automatically and any cosmetic adjustment impacts aerodynamics... because it’s basically a new shape). 

Any parts that appear to have changed that haven’t been updated cosmetically in 1.5 shouldn’t be anything to do with squad unless either I or they haven’t been very thorough with the change log

Edited October 26, 2018 by MR L A

[OHara]

Nice test.  You can test whether the change is due to parts or aerodynamics by copying the old craft-files or searching for the old parts (like the TR-18A decoupler) in the advanced tab in the VAB.

With identical parts, I get the same results versions 1.3--1.5, so I think the effect is due to how the slightly-different diameters of the new versions of parts line up with the old booster. (You can see differences in m² surface area between similar parts PartDatabase.cfg, but between versions the differences are just rounding error.)

In general I don't see any difference in aerodynamics between 1.3  through 1.5.1 (except for the bugs that came and went).