Beale

[1.10.X] Tantares - Stockalike Soyuz and MIR [2.0][04.08.2020][Venera 9]

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On 1/26/2020 at 8:37 PM, Beale said:

Full KTDU-51 engine. 3 parts vs. the old 1

MWS5Spd.jpg

Monopropelant?
Ideal for Soyuz...

SOYUZ_LANDER.jpg?ver=0

Edited by kopapaka

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Just now, kopapaka said:

Monopropelant?
Ideal for Soyuz...

SOYUZ_LANDER.jpg?ver=0

Yes, For sure! Nice lander

Edited by Beale

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I need some help... no matter what i do, my soyuz always turns around mid-air and is impossible to launch without failure... what am i doing  wrong?? it has nothing to do with my other mods, as i have this issue even when only tantares is installed.. i have tried both mechjeb, gravity turn, and doing a manual gravity turn but it still keeps turning around when i reach about 200-300 m/s

craft file: https://drive.google.com/open?id=1Puq3j6QbhCT6mo6usSz0vI-TMu7HuDB1

Edited by Fredde104

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2 hours ago, Fredde104 said:

I need some help... no matter what i do, my soyuz always turns around mid-air and is impossible to launch without failure... what am i doing  wrong?? it has nothing to do with my other mods, as i have this issue even when only tantares is installed.. i have tried both mechjeb, gravity turn, and doing a manual gravity turn but it still keeps turning around when i reach about 200-300 m/s

craft file: https://drive.google.com/open?id=1Puq3j6QbhCT6mo6usSz0vI-TMu7HuDB1

Do you have the fins attached to the side boosters? Also, I usually attach RCS to the core stage for additional control. It seems like you are having a drag issue at a high center of gravity on the launch vehicle. 

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13 hours ago, Fredde104 said:

I need some help... no matter what i do, my soyuz always turns around mid-air and is impossible to launch without failure... what am i doing  wrong?? it has nothing to do with my other mods, as i have this issue even when only tantares is installed.. i have tried both mechjeb, gravity turn, and doing a manual gravity turn but it still keeps turning around when i reach about 200-300 m/s

craft file: https://drive.google.com/open?id=1Puq3j6QbhCT6mo6usSz0vI-TMu7HuDB1

I had/have the same problem for .. a long time. I've only been able to reliably solve the issue by editing the parts config files and dramatically increasing the weight of the upper "bulge" tanks to shift the center of gravity way up.

Edited by tjsnh

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0eFyFDF.gif

Tried launching Beale's Soyuz and had no flips.

 

Would have tried with your craft @Fredde104, but there are parts I don't know from which mods they are from.

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On 1/26/2020 at 3:41 PM, Beale said:

Old -> New

mxBWtH9.jpg
sMg7XY0.jpg

The new one also looks good, but I like the old one as well.

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23 minutes ago, Random Annoying Guy said:

??? they are the same except the top part

No they aren't.  Attention to detail, my lad.  Check the panel lines on the bottom. Color is slightly different, too.

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17 hours ago, Fredde104 said:

I need some help... no matter what i do, my soyuz always turns around mid-air and is impossible to launch without failure... what am i doing  wrong?? it has nothing to do with my other mods, as i have this issue even when only tantares is installed.. i have tried both mechjeb, gravity turn, and doing a manual gravity turn but it still keeps turning around when i reach about 200-300 m/s

craft file: https://drive.google.com/open?id=1Puq3j6QbhCT6mo6usSz0vI-TMu7HuDB1

3 hours ago, tjsnh said:

I had/have the same problem for .. a long time. I've only been able to reliably solve the issue by editing the parts config files and dramatically increasing the weight of the upper "bulge" tanks to shift the center of gravity way up.

Unfortunately I can't test the craft as it has parts from a bunch of other mods I don't have.

I think as @Pkmniako shows though, the Soyuz as it is should fly pretty flawlessly to orbit, honestly it's a real mule and I have used and abused it to space and back, flying not so carefully with the throttle maxed all the way.

I really need to know what you guys are doing on launch, could you take a video? Flying straight up and doing a sharper 45 turn at 10km up? a.k.a. KSPs old aerodynamic system.
Not to be grumpy, but this problem always goes quiet when I start digging into how people are flying, vs. what they are flying :D

With any realistically proportion rocket in KSP you do have to fly along the prograde and gradually lean over.

 

GiTdFOq.jpg
2erznHZ.jpg

Edited by Beale

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As far as i know, i have only used parts from this... but i might be wrong, its been years since i made the file, then its just the payload that has been "upgraded". However i will try to increase the mass of the upper tank to get the CoM higher and try again. If that wont help, maybe the new parts work better? Im still using the "old" rocket parts with the new spacecraft parts

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20 hours ago, Beale said:

I really need to know what you guys are doing on launch, could you take a video? Flying straight up and doing a sharper 45 turn at 10km up? a.k.a. KSPs old aerodynamic system.
Not to be grumpy, but this problem always goes quiet when I start digging into how people are flying, vs. what they are flying :D

 

 

I generally ascend vertically until reaching 300m/s (roughly, sometimes a little more or less) then start to slowly bank over to a 45degree inclined climb.

Usually about 20 degrees into the bank, I get a "flip" where the R-7 stack does a somersault. After it does its flip, its usually recoverable, but without my weight fixes (or a seriously over-heavy payload) its unavoidable for me. I've tried with fins, without fins, different types of fairings, no fairing, banking slowly, banking quickly, etc etc. The CG ends up being just too low. The only fixes I've found are to reduce the weight of the strap-on boosters down to almost nothing (which makes the rocket even more OP with stock physics/planet) or to make the bulge tanks heavier (which has the added benefit of a mild nerf to the booster) - both of which shift the CG up a bit.

Important note - when the flip happens, it doesn't tumble out of control ... it usually just does ONE uncontrollable flip , then reorients itself with some mild WASD inputs. This is before side-booster separation. My guess is that its due to the CG shifting relative to the length of the rocket as stage 1 burns fuel and that KSP's physics and/or aerodynamic model just handles that transition oddly for these parts.

Edited by tjsnh

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I'm thinking the 200-300m/s might be the issue here, pitching over at higher speeds might be catching a lot of air and flipping things over. I usually start a turn around 100m/s and try to keep acceleration down with either plenty of throttle control or lowering the first stage thrust to a lower TWR.

Edit: Just tried out starting turn at 300m/s. With fins on, I can barely get the rocket to turn, let alone flip. Without fins, I did have a flip at around 550m/s and around 30° into the turn.

Edited by Fly Angry

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5 hours ago, Fredde104 said:

As far as i know, i have only used parts from this... but i might be wrong, its been years since i made the file, then its just the payload that has been "upgraded". However i will try to increase the mass of the upper tank to get the CoM higher and try again. If that wont help, maybe the new parts work better? Im still using the "old" rocket parts with the new spacecraft parts

Definitely use the most latest version, I am not sure how the aero is working on the older model :)

4 hours ago, tjsnh said:

 

I generally ascend vertically until reaching 300m/s (roughly, sometimes a little more or less) then start to slowly bank over to a 45degree inclined climb.

Usually about 20 degrees into the bank, I get a "flip" where the R-7 stack does a somersault. After it does its flip, its usually recoverable, but without my weight fixes (or a seriously over-heavy payload) its unavoidable for me. I've tried with fins, without fins, different types of fairings, no fairing, banking slowly, banking quickly, etc etc. The CG ends up being just too low. The only fixes I've found are to reduce the weight of the strap-on boosters down to almost nothing (which makes the rocket even more OP with stock physics/planet) or to make the bulge tanks heavier (which has the added benefit of a mild nerf to the booster) - both of which shift the CG up a bit.

Important note - when the flip happens, it doesn't tumble out of control ... it usually just does ONE uncontrollable flip , then reorients itself with some mild WASD inputs. This is before side-booster separation. My guess is that its due to the CG shifting relative to the length of the rocket as stage 1 burns fuel and that KSP's physics and/or aerodynamic model just handles that transition oddly for these parts.

Thanks for the detailed observations, but I cannot reproduce at all :(
Craft file using only Tantares parts (Last full release)

If this doesn't work for you, I can only think:

  • Using any mods that might affect aero or overall balance? (I would be very grumpy if you were using FAR and completely neglected to mention that :D )
  • Your physics settings maybe?
  • Install issue? Tried deleting partdatabase.cfg?

If you could:

  • Take a video (I know this might not be easy / possible, you can use OBS to record https://obsproject.com/ )
  • Screenshot GameData folder

I flew to orbit, full throttle and with timewarp very sloppily, no issues:

lKIaZm4.jpgm0MK7XK.jpgwlsS52Y.jpg

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7 hours ago, tjsnh said:

 

I generally ascend vertically until reaching 300m/s (roughly, sometimes a little more or less) then start to slowly bank over to a 45degree inclined climb.

Usually about 20 degrees into the bank, I get a "flip" where the R-7 stack does a somersault. After it does its flip, its usually recoverable, but without my weight fixes (or a seriously over-heavy payload) its unavoidable for me. I've tried with fins, without fins, different types of fairings, no fairing, banking slowly, banking quickly, etc etc. The CG ends up being just too low. The only fixes I've found are to reduce the weight of the strap-on boosters down to almost nothing (which makes the rocket even more OP with stock physics/planet) or to make the bulge tanks heavier (which has the added benefit of a mild nerf to the booster) - both of which shift the CG up a bit.

Important note - when the flip happens, it doesn't tumble out of control ... it usually just does ONE uncontrollable flip , then reorients itself with some mild WASD inputs. This is before side-booster separation. My guess is that its due to the CG shifting relative to the length of the rocket as stage 1 burns fuel and that KSP's physics and/or aerodynamic model just handles that transition oddly for these parts.

it's the first vertical ascend that's doing it. Try going vertical for 100m/s and then bank 5 degrees. And then just let it follow prograde. should be 45 degrees around 10km in altitude. If that gives you a too steep of a trajectory try starting your turn earlier (somewhere between 50m/s and 100m/s). And then just finetune it in the following launches.

Back of the throttle if you are not at 45 degrees at 10km. 

This is the same for you: @Fredde104 

3 hours ago, Beale said:


Thanks for the detailed observations, but I cannot reproduce at all :(
Craft file using only Tantares parts (Last full release)

<snip>

It is NOT an issue with your mod. I have used it since forever and never had any problems. The first time the issue has popped up on this thread (long time ago) it always was somebody flying it like they used to in the souposphere.

Edited by lrd.Helmet

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i seem to have find the issue by accident.. im using a scaled down rss and did the atmosphere to the wrong scale. i changed it from .7 to .55 and now the ascent goes perfect

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On 1/26/2020 at 9:07 PM, Fredde104 said:

I need some help... no matter what i do, my soyuz always turns around mid-air and is impossible to launch without failure... what am i doing  wrong?? it has nothing to do with my other mods, as i have this issue even when only tantares is installed.. i have tried both mechjeb, gravity turn, and doing a manual gravity turn but it still keeps turning around when i reach about 200-300 m/s

craft file: https://drive.google.com/open?id=1Puq3j6QbhCT6mo6usSz0vI-TMu7HuDB1

 

As with every rocket, you should fly straight for the first kilometers, to clear the lower, denser air. I never start turning below 10k. Doing intense maneuvering in denser air is a sure recepy for this kind of control loss. I mean, some particularly well-designed rockets are more stable and you can do anything with them, but that is not "by the book". Try not changing anything, except flying fully straight until you pass the 10k threshold - and even so, do only incremental attitude adjustments. Then report back here and let's see if the problem persists.

Edited by Daniel Prates

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28 minutes ago, Daniel Prates said:

 

As with every rocket, you should fly straight for the first kilometers, to clear the lower, denser air. I never start turning below 10k. Doing intense maneuvering in denser air is a sure recepy for this kind of control loss. I mean, some particularly well-designed rockets are more stable and you can do anything with them, but that is not "by the book". Try not changing anything, except flying fully straight until you pass the 10k threshold - and even so, do only incremental attitude adjustments. Then report back here and let's see if the problem persists.

This turning above 10km idea is from the old KSP aero model. This is NOT optimal anymore. For the vast majority of reasonably designed rockets, you

1) start a gravity turn by nudging 10 degrees in the direction you are launching it at 100-150m/s then holding prograde.  (you can also start gentler earlier but this is pretty safe)

2) disable prograde hold at 45 degrees if you find yourself at 45 degrees before reaching 20-25km.

3) Then go as horizontal as possible from there keeping Ap at least 30s away (at stock scale, in 2.5x you prob want to keep it 60-90s away)

4) establish Ap and then circularise at Ap (or learn to do a single burn to orbit,)

See the gif pkmniako posted which illustrates a proper gravity turn.

That 10km thing these days would only be necessary for something with horrible aero like trying to launch an unshielded space station or something.

Edited by Zorg

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