did the atmosphere get thicker in 1.9?

[Xyphos]

Normally, I don't have trouble building and/or flying SSTO SpacePlanes, but ever since the update, I can't get one into orbit, including ones built in previous versions.

while testing, I had a TWR of ~2.2 and still couldn't get past ~340 m/s with Rapier engines, which eventually decreased speed the higher I went up.

so what gives?

[Rhomphaia]

Rapiers have poor performance at subsonic speeds. you are going to want to build up speed in level flight at low altitudes, don't start climbing until you get over 400m/s

[Blaarkies]

Something interesting I found is that when a cargo bay is set as open, but with a deploy limit of 0 it looks closed, but aerodynamics will calculate it as being open and apply drag force on all the hardware inside the cargo bay and connecting sections. This happens when you fiddle with KAL-9000 controllers to handle the bay doors.

If it is unintended drag like this, you can easily find the culprit. Press Alt+F12 for the debug menu, go to aero, tick the checkbox for display drag values in GUI. Now when you right click any part of your craft, you can see the drag force applied (and other values as well). Now just find the one that has way more drag than it should have to pin down the issue.

[AHHans]

1 hour ago, Blaarkies said:

Something interesting I found is that when a cargo bay is set as open, but with a deploy limit of 0 it looks closed, but aerodynamics will calculate it as being open and apply drag force on all the hardware inside the cargo bay and connecting sections.

In related news, I recently figured out that if you have a cargo inside a cargo bay and trigger the decoupler to this cargo when starting the engines, then this loose cargo will generate as much drag as if it was outside the cargo bay in the airstream.

P.S. Check Yo' Stagin'!

[Laie]

On 5/6/2020 at 1:14 PM, Xyphos said:

Normally, I don't have trouble building and/or flying SSTO SpacePlanes, but ever since the update, I can't get one into orbit, including ones built in previous versions.

I've heard about changes in drag wrt the 1.8 update, but not 1.9.

Generic suggestion to anyone suffering from unexpected drag: turn on drag values in the PAW and look if something sticks out.

[Xyphos]

I solved the problem.
Just as @Blaarkies said, the cargo bays were the major source of drag;
for some unknown reason, the bays were closed and didn't have their deploy settings tampered with, but flew as if they were open.
strange bug I guess?
the solution was to rebuild the vessel with new cargo bays and it worked.

[ExtremeSquared]

On 5/9/2020 at 5:09 AM, Laie said:

I've heard about changes in drag wrt the 1.8 update, but not 1.9.

Generic suggestion to anyone suffering from unexpected drag: turn on drag values in the PAW and look if something sticks out.

Aero gets tweaked all the time without making it into the changelog. It's been this way from the beginning.

[Fraktal]

At this point, it would be just flat-out better if they stopped toggling the damn cargo bays' drag every time they're opened or closed. Just leave 'em perpetually closed.

[qzgy]

33 minutes ago, Fraktal said:

At this point, it would be just flat-out better if they stopped toggling the damn cargo bays' drag every time they're opened or closed. Just leave 'em perpetually closed.

You lose a very good aerobreaking option though..... that would make some people very sad

(myself maybe included)

[Xyphos]

aye, the increased drag from an open cargobay makes a world of difference when you're attempting an aerobrake/aerocapture.
it just a weird bug I experienced, been playing since 0.90 and never had this happen before

[Wilds]

I sometimes get a bug where the cargo bay has far more drag than usual, so I have to open it and close it back to get it to act normally.