[1.12.X] Tantares - Stockalike Soyuz and MIR [16.1][28.05.2024][Mars Expedition WIP]

[tjsnh]

craft file I'm launching :

http://kerbalx.com/tjsnh/R7a-testing

(ignore the pic)

Super basic R-7. No (other) mods.

I've tried 10 different launch profiles. Full throttle, half throttle, tip at 7k, tip at 15k, etc etc.

Flips back-end-first every. single. time.

I've never had this problem with any R7 based tantares rockets before. What am I doing wrong?

[MK3424]

craft file I'm launching :

http://kerbalx.com/tjsnh/R7a-testing

(ignore the pic)

Super basic R-7. No (other) mods.

I've tried 10 different launch profiles. Full throttle, half throttle, tip at 7k, tip at 15k, etc etc.

Flips back-end-first every. single. time.

I've never had this problem with any R7 based tantares rockets before. What am I doing wrong?

Add small fins to the engines and make shure to keep your angle of attack on your prograde marker below 5°.

[CaptKordite]

I've had issues with the R7 flip, even in the previous versions. I was never able to get the hang of adjusting the throttle on ascent. I tend to solve it with a consistent gravity turn and limiting the engine thrust to have a 2.0 TWR at launch.

I have to go back and rebuild a bunch of craft then re-upload them to Kerbal X.

[tjsnh]

Add small fins to the engines and make shure to keep your angle of attack on your prograde marker below 5°.

The fins didn't make a lot of difference (I was using them originally), but keeping the AoA within 5 degrees worked .. kindof .. no flip, but after about a dozen tries I can't get into a launch profile with an aps below 100km. Not really a "problem" but it's going to radically alter things for me - 100km is my standard parking orbit. I wish I knew what was so different about the new vs the old .. ah well. I'll be playing around with increasing the tank weights as a nerf (like I did before), maybe that will resolve the issues I'm having.

[DurinVIII]

It's part of his new spinoff early-rocketry style mod now!

Those verniers look amazing with RD-107 by the way Beale <3

Ah, I must have missed that.

That's right, it will be available in Taerobee (but remade as a the Bumper and R1 rockets).

Mainly I want to do away with the V-2 as I am sick of the constant weird requests for nðzi planes, tanks, etc.

Probably should not have made it in the first place.

I can understand that and I find it very odd that people would make such requests of you. Ah well, c'est la vie. I am sure we will all be quite pleased with whatever you come up with. Thanks again for all your hard work!

Cheers!

[captainradish]

I kind-of liked the V2 myself, although I never used it beyond the "Launch our first vessel" and "Gather scientific data from Kerbin."

[tjsnh]

Well I'm pretty close to giving up on the new R-7 parts.

I've tried at least 15 different troubleshooting design changes (fins, verniers, increasing engine/tank weights in the config files,etc) and no matter what I do, during assent if the directional pip moves even 2 or 3 pixels out of the lime green circle (direction of flight indicator) on the artificial horizon, the rocket flips. I've had one good launch, out of at least 50 attempts so far, and the launch profile was almost vertical until escaping the atmosphere (was barely 10degrees off vertical @ 50k meters).

I can't be the only one having this problem. The basic design (as the craft i linked a few posts up) shoudn't have such a tiny (2 or 3 degrees) directional window before it flips completely out of control and is entirely non-recoverable into normal flight.

It's only been a problem since the new release, and as much as I love the new parts if the rocket is completely unflyable there isn't much that can be done to salvage it for regular use.

If anyone has a solution for this (design/construction change, modulemanager patch to change the center of gravity, really anything!) please, for the love of Korolev, share it.

Otherwise it's back to the previous version of the R-7 parts.

Edited September 9, 2015 by tjsnh

[passinglurker]

Well I'm pretty close to giving up on the new R-7 parts.

I've tried at least 15 different troubleshooting design changes (fins, verniers, increasing engine/tank weights in the config files,etc) and no matter what I do, during assent if the directional pip moves even 2 or 3 pixels out of the lime green circle (direction of flight indicator) on the artificial horizon, the rocket flips. I've had one good launch, out of at least 50 attempts so far, and the launch profile was almost vertical until escaping the atmosphere (was barely 10degrees off vertical @ 50k meters).

I can't be the only one having this problem. The basic design (as the craft i linked a few posts up) shoudn't have such a tiny (2 or 3 degrees) directional window before it flips completely out of control and is entirely non-recoverable into normal flight.

It's only been a problem since the new release, and as much as I love the new parts if the rocket is completely unflyable there isn't much that can be done to salvage it for regular use.

If anyone has a solution for this please for the love of Korolev share it.

Otherwise it's back to the previous version of the R-7 parts.

did you try deleting PartDatabase.cfg in the root folder like when the parachutes went wonky after 1.0 hit?

[tjsnh]

did you try deleting PartDatabase.cfg in the root folder like when the parachutes went wonky after 1.0 hit?

Yep...

(I'm also on a fresh install - actually JUST got done reformatting my PC yesterday - and with no other mods)

Edited September 9, 2015 by tjsnh

[passinglurker]

Yep...

hmmm... how about decreasing engine weight so there isn't as much mass to the rear? or using far?

[tjsnh]

hmmm... how about decreasing engine weight so there isn't as much mass to the rear? or using far?

I've tried reducing the engine weight, seemed to make the problem worse. I'd really rather not have to resort to installing another addon (far) just to get the basic R-7 to work, especially as I don't want to have to add any other dependencies for the career-mode mods I manage that rely on tantares for parts....

[passinglurker]

I've tried reducing the engine weight, seemed to make the problem worse. I'd really rather not have to resort to installing another addon (far) just to get the basic R-7 to work, especially as I don't want to have to add any other dependencies for the career-mode mods I manage that rely on tantares for parts....

I suggested far more as a matter of troubleshooting than a permanent solution. If they behave the same in far then there must be something wrong with the parts where as if they work correctly in far then there is something wrong with stock aerodynamics(or at least your stock install)

[tjsnh]

As an illustration :

Note the altitude, speed, and aerodynamic overlay. I took this screenshot literally less than a second before the rocket flips out of control. The game client hiccups for a moment when I hit printscreen (like when you autosave), and JUST after the hiccup the rocket flipped. So .. this pic is basically a perfect example of my flight situation. Notice that my direction of flight is just barely outside the lime green circle.

I mean ..... it seems like being that close to vertical, at 10k meters, at only 400 m/s , shouldnt put the rocket into an unrecoverable flight state ... the amount of sideways lift generated by the top tank seems WAY too large ..

[hraban]

As an illustration :

http://oi58.tinypic.com/in5mj9.jpg

Note the altitude, speed, and aerodynamic overlay. I took this screenshot literally less than a second before the rocket flips out of control. The game client hiccups for a moment when I hit printscreen (like when you autosave), and JUST after the hiccup the rocket flipped. So .. this pic is basically a perfect example of my flight situation. Notice that my direction of flight is just barely outside the lime green circle.

I mean ..... it seems like being that close to vertical, at 10k meters, at only 400 m/s , shouldnt put the rocket into an unrecoverable flight state ... the amount of sideways lift generated by the top tank seems WAY too large ..

Let us please know how large the payload of your R-7's configuration.

Should this be less than 1.3 tons, the flight behavior explains itself.

In addition, it is never wrong to install a reaction wheel.

[Beale]

Well I'm pretty close to giving up on the new R-7 parts.

I've tried at least 15 different troubleshooting design changes (fins, verniers, increasing engine/tank weights in the config files,etc) and no matter what I do, during assent if the directional pip moves even 2 or 3 pixels out of the lime green circle (direction of flight indicator) on the artificial horizon, the rocket flips. I've had one good launch, out of at least 50 attempts so far, and the launch profile was almost vertical until escaping the atmosphere (was barely 10degrees off vertical @ 50k meters).

I can't be the only one having this problem. The basic design (as the craft i linked a few posts up) shoudn't have such a tiny (2 or 3 degrees) directional window before it flips completely out of control and is entirely non-recoverable into normal flight.

It's only been a problem since the new release, and as much as I love the new parts if the rocket is completely unflyable there isn't much that can be done to salvage it for regular use.

If anyone has a solution for this (design/construction change, modulemanager patch to change the center of gravity, really anything!) please, for the love of Korolev, share it.

Otherwise it's back to the previous version of the R-7 parts.

As an illustration :

http://oi58.tinypic.com/in5mj9.jpg

Note the altitude, speed, and aerodynamic overlay. I took this screenshot literally less than a second before the rocket flips out of control. The game client hiccups for a moment when I hit printscreen (like when you autosave), and JUST after the hiccup the rocket flipped. So .. this pic is basically a perfect example of my flight situation. Notice that my direction of flight is just barely outside the lime green circle.

I mean ..... it seems like being that close to vertical, at 10k meters, at only 400 m/s , shouldnt put the rocket into an unrecoverable flight state ... the amount of sideways lift generated by the top tank seems WAY too large ..

I really do not know what you are doing wrong, I do not experience forces anything like this strong.

My Sputnik launcher was almost completely horizontal by 40KM up.

This new aero system, eh...

Edited September 9, 2015 by Beale

[tjsnh]

When are you starting your gravity turn?

I usually start mine (with every other rocket) at about 8k

Also :

Further troubleshooting has found the following observations.

Launching in a "full" soyuz configuration, with the upper stage and a soyuz/progress payload, the flight profile on assent is controllable and close to stable. Only minor hiccups, and after 3 tries I got a stable, repeatable, launch profile.

Without the second stage , ie : in a "sputnik" configuration , using the exact same lower half as the soyuz test and only a probe core as payload, the rocket is entirely uncontrollable as described in previous posts.

This seems counterintuitive to me, as a heavier top should make the rocket more prone to tipping (but then again - it IS ksp after all ..).

Anyone have a suggestion on how to get around this behavior for 'sputnik' style launches?

Edited September 9, 2015 by tjsnh

[Beale]

When are you starting your gravity turn?

I usually start mine (with every other rocket) at about 8k

8km up too

As you can see I'm @ 30 degrees at 35km and then almost @ 90 at 50km.

Very gently, but I realize I have made a very small change to the config since release.

Try this:

Replace in tank files.

dragModelType = default
maximum_drag = 0.20
minimum_drag = 0.15

With this.

dragModelType = default
maximum_drag = 0.2
minimum_drag = 0.3

Any different?

[Sackpfeife]

When are you starting your gravity turn?

I usually start mine (with every other rocket) at about 8k

at 8 Kilometers?

I start mine at 800 meters

But i experienced a different launch-behavior with the new Soyuz launcher:

After staging the 4 booster, the rocket starts rolling left and right and left and right, but that might have to do with MechJeb...

[tjsnh]

###########I solved the problem. ###########

I changed the dry weight of the bulge tank (using a MM patch) to 5 tons.

Primitive, and makes the bulge tank useless for anything else (which is fine for me), but it completely solved the problem. Launch is stable in soyuz and sputnik configurations, and in fact it ends up being enough of a 'nerf' to bring the performance right where I want it. (IE: sputnik config juuuuust gets a light probe into LKO, and soyuz config can get a soyuz payload halfway to Mun, or a light probe to Mun).

This change will be included in my career-mode soviet space program mod.

@PART[TLV_LFO_B]
{
  @mass = 5
}

Edited September 9, 2015 by tjsnh

[CatastrophicFailure]

As an illustration :

http://oi58.tinypic.com/in5mj9.jpg

Note the altitude, speed, and aerodynamic overlay. I took this screenshot literally less than a second before the rocket flips out of control. The game client hiccups for a moment when I hit printscreen (like when you autosave), and JUST after the hiccup the rocket flipped. So .. this pic is basically a perfect example of my flight situation. Notice that my direction of flight is just barely outside the lime green circle.

I mean ..... it seems like being that close to vertical, at 10k meters, at only 400 m/s , shouldnt put the rocket into an unrecoverable flight state ... the amount of sideways lift generated by the top tank seems WAY too large ..

Guys, guys, guys... I've been watching this little exchange for a while now and the trouble this fellow is having is pretty obvious:

Y'ALL ARE STARTING YOUR GRAVITY TURNS WAY! TOO! LATE!

Ever since they gave us the new aerodynamics in 1.whatever, this old "go up several kilometers then turn right" thing that's so ingrained in us NO LONGER APPLIES. It doesn't work anymore! It's an obsolete procedure! The "proper" (read: efficient, stable, sustainable) way to launch now is to start your gravity turn AS SOON AS POSSIBLE, basically as soon as you've got enough speed for aerodynamic control, which is usually around 100m/s and perhaps one kilometer off the pad. Look at how real rockets do it. They start their pitchover maneuver virtually as soon as they've cleared the tower. The actual height may vary depending on TWR but 100m/s seems to be the ideal in nearly every case. Heck, I've got some high TWR all-solid launchers that start out on the pad tilted 10 or 15 degrees over.

Those of us who use FAR have already been doing it this way for a while so it's a simple adjustment, but this old "go up, THEN turn right" mantra has got to go. It's simple physics. If you've got the momentum of a many-ton rocket going nearly the speed of sound straight up, it's gonna be REALLY hard to change that momentum. Start the turning impulse when your momentum is much lower, then just let gravity do its thing.

[minepagan]

Guys, guys, guys... I've been watching this little exchange for a while now and the trouble this fellow is having is pretty obvious:

Y'ALL ARE STARTING YOUR GRAVITY TURNS WAY! TOO! LATE!

Ever since they gave us the new aerodynamics in 1.whatever, this old "go up several kilometers then turn right" thing that's so ingrained in us NO LONGER APPLIES. It doesn't work anymore! It's an obsolete procedure! The "proper" (read: efficient, stable, sustainable) way to launch now is to start your gravity turn AS SOON AS POSSIBLE, basically as soon as you've got enough speed for aerodynamic control, which is usually around 100m/s and perhaps one kilometer off the pad. Look at how real rockets do it. They start their pitchover maneuver virtually as soon as they've cleared the tower. The actual height may vary depending on TWR but 100m/s seems to be the ideal in nearly every case. Heck, I've got some high TWR all-solid launchers that start out on the pad tilted 10 or 15 degrees over.

Those of us who use FAR have already been doing it this way for a while so it's a simple adjustment, but this old "go up, THEN turn right" mantra has got to go. It's simple physics. If you've got the momentum of a many-ton rocket going nearly the speed of sound straight up, it's gonna be REALLY hard to change that momentum. Start the turning impulse when your momentum is much lower, then just let gravity do its thing.

Allow me to sum that up:

Start your gravity turns at a velocity not an altitude.

Recommended velocity is somewhere from 100-200 m/s.

Just gradually turn. Not 'turn parallel with the surface in 3 seconds'.

[tjsnh]

Guys, guys, guys... I've been watching this little exchange for a while now and the trouble this fellow is having is pretty obvious:

Y'ALL ARE STARTING YOUR GRAVITY TURNS WAY! TOO! LATE!

[CatastrophicFailure]

Failure is how we learn. Sometimes we learn a whole bunch all at once and it involves explosions and rockets breaking in half.

[tjsnh]

Failure is how we learn. Sometimes we learn a whole bunch all at once and it involves explosions and rockets breaking in half.

Really, the failure is half the fun

[Beale]

Guys, guys, guys... I've been watching this little exchange for a while now and the trouble this fellow is having is pretty obvious.

Y'ALL ARE STARTING YOUR GRAVITY TURNS WAY! TOO! LATE!

It's not that obvious.

Try it yourself with this rocket, it will flip if you try and use the proper method.

Just, seemingly not quite as severe as tjsnh is describing.

Really it makes getting an apoapsis lower than 100km pretty much impossible, it's true.

Edited September 9, 2015 by Beale