Why doesn't the rocket in the game perform the same as the training rocket?

[Zeggpold]

Long story short, I do the first two training missions (build and launch).  Everything goes fine.  If I do the same thing in the actual game, the rocket goes higher (altitude of around 23000 rather than around 15000).  The result is that the parachute won't work:  if I change the pressure value to 0.2 (as in the training mission), the parachute never deploys (it turns blue in the staging, then the background turns red---see screen shots).  If I don't change the parachute, it deploys and then is destroyed.

Linux, 64 bits, version 1.5.1.2334 (linuxPlayer) en-us on Ubuntu 14.04, store version (not steam) no mods.
Log files plus screenshots on dropbox here.

Of course, I can decrease the amount of propellant in the Flea SRB to avoid this, bit it seems unlikely that should be necessary.  (Especially as I didn't find anything else on this searching the forums.)  Does this indicate something wrong with my game or system?  I did try reinstalling (which is to say unzipping the file again) and downloading again, but neither helped.  Any idea what could be wrong?

[OHara]

I get the same result, so not likely anything wrong with your install.    

The new look of the flea booster seems to have come with some (accidental?) performance improvement.   

It sounds like you already know how to deal with this: reduce the thrust, or let the higher-performing flea lift more mass, etc.

Edit: maybe not a bug.. 

The difference is in the drag, which is calculated from the shape (no overrides for these particular parts) and the new shape is just a bit more aerodynamic. 

That tiny difference in shape happens to get magnified by games they played with drag back in version 1.2 (exaggerating the differences in drag-force from different drag coefficients Cd) and the solid boosters do their work in the thickest part of the atmosphere, so a small shape change made big a difference in height

Edited December 9, 2018 by OHara

[Plusck]

I think it's an essential lesson, that is relevant to what we puny humans do as we try to emulate the Kerbals.
If you're going up high, you do NOT want to go vertically up, since that means coming vertically back down. Going up, your vertical speed is limited by gravity pulling you back. Coming back down, the only limit is drag; if there is hardly any atmosphere, there is hardly any drag; it is easy to go supersonic just by falling; parachutes aren't very good at dealing with supersonic airflow.

So don't fall vertically, ever. You need time and/or distance in the lower atmosphere to slow down, and the only way to get that is to go sideways.

It is said that it isn't the fall that kills you, it's the sudden stop at the end. When it comes to the very highest skydiving records, however, when you end up tumbling wildly at supersonic speeds with no way of stabilising yourself or slowing yourself down, it can easily be both.
And if you're in a heavy pointy metal box, rather than a light and floppy pressure suit, that uncontrolled tumbling will invariably become a dart-like bunker-busting trajectory as you zip though just a few seconds-worth of heavier atmosphere.

[Rocket In My Pocket]

You can still do it just fine without mucking with the Flea, or adding arc to your trajectory; you just need to wait till you are going very slow at the apex of your ascent to activate the parachute.

Spoiler

 

 

Edited December 10, 2018 by Rocket In My Pocket

[bewing]

OHara has it right, and Rocket In My Pocket, too.

Open your parachute on the way up -- the extra drag will keep the speeds low enough to prevent parachute destruction.

 

[Zeggpold]

Thanks for the inputs, everyone.

Ohara, thanks for the analysis.  It does look like the shape of the booster is different in the training flight.  As you say, I know how to work around this (and there are more ideas below), but I wonder about a newcomer.

Plusck, that's a great point.  Too bad Squad didn't see fit to include it in the training flight.

Rocket in My Pocket, your flight looks like just what I was trying to do at first.  But when I try that with the chute set to the defaults, I get a message "[Mk16 Parachute]: Chute destroyed by aero forces and heat" at an altitude of about 9500.  (I also don't see the same information as you in the parachute info box.)  My flight on youtube (doesn't seem to be embedable for some reasons): https://youtu.be/Ae3txAVECho. if you (or anyone) could see what I'm doing differently, I'd love to hear it.

bewing, that's another great idea that Squad didn't see fit to mention in the training flight.

 

[bewing]

1 hour ago, Zeggpold said:

that's another great idea that Squad didn't see fit to mention in the training flight

This game is about discovering things on your own. Squad will never give you anything more than a hint or two.

[Rocket In My Pocket]

The extra info is prolly from having advanced tweakables options enabled.

I didn't muck with any settings though they are all default.

Did you change the parachute settings to what they use in the tutorial? I didn't, may be the difference? The main difference I see watching the two vids is that I had SAS enabled and thus fell butt first while you didn't and ended up going nose first. Might be just enough extra speed to burn up the chute?

Edited December 10, 2018 by Rocket In My Pocket

[Zeggpold]

On 12/10/2018 at 3:37 AM, Rocket In My Pocket said:

The extra info is prolly from having advanced tweakables options enabled.

I didn't muck with any settings though they are all default.

Did you change the parachute settings to what they use in the tutorial? I didn't, may be the difference? The main difference I see watching the two vids is that I had SAS enabled and thus fell butt first while you didn't and ended up going nose first. Might be just enough extra speed to burn up the chute?

The video was the attempt with the parachute unaltered.  I hadn't noticed the SAS but that might be the difference.  I'll give it a try when I have a chance.

[edit]Yup, that was the difference.

Thanks to all, I'm marking OHara's answer as "the answer" since that's the one that answered my title question.[/edit]

Edited December 14, 2018 by Zeggpold
Update