How much Delta-V to orbit Kerbin ?

[cramtenahc]

With the aerodynamics changements i don't know anymore how many delta-v it needs to orbit Kerbin.

My last vessel do an orbit at 80km but has only 2000 m/s of delta-v and i saw on my map of delta-v that it should require 4500 m/s to orbit ...

If someone can help. Thanks.

Edited May 1, 2015 by cramtenahc

[viktor19]

With the aerodynamics changements i don't know anymore how many delta-v it needs to orbit Kerbin.

My last vessel do an orbit at 80km but as only 2000 m/s of delta-v and i saw on my map of delta-v that it should require 4500 m/s to orbit ...

If someone can help. Thanks.

You probably looked at the old delta-v map. Aerodynamics have changed in 1.0 and so have delta-v requirements. Guess we'll have to wait until someone makes a new and improved.

[capi3101]

The observations most folks have been getting so far generally put the new LKO delta-V requirement between 3500-4000 m/s of delta-V, depending on how well you fly. The 4500 figure is indeed based on the old aerodynamic system, and it'll probably be a while until folks will have time to update the delta-V maps.

[cramtenahc]

Ok thanks ! I will wait for

[Shpaget]

Just did a small test with a small single stage probe rocket.

At start it had 4242 m/s dv in vacuum, 3587 at sea level. I pushed it in LKO (71 x 77 km) and had 787 ms/ remaining (800 kg of fuel).

So, less than 3500 for a SSTO with almost 1 ton of cargo.

It really depends on the engines you use in low atmosphere where ISP is reduced.

Edited May 1, 2015 by Shpaget

[funk]

After lifting over 30 crafts to LKO I've recognized, that an initial TWR of 1.6-1.75 is the most efficient. I mostly need between 3200-3300m/s for light and for heavy crafts. Record so far is 3050m/s.

Go as fast as you can and try to do a proper gravity turn. The lower TWR the higher you'll have to start he turn - for high TWR around 50m/s vertical speed, for very low TWR perhaps when surface velocity is 100m/s and more. Slight burning effects above 10km seem to indicate the most efficient ascent path (height/velocity relation).

[SanderB]

I've achieved 2,746 m/s of vacuum dV in a 100t vehicle, pitching to 30° degrees very early on and lessening thrust to 20m/s at some point to prevent burning up. The heavier, more massive and aerodynamic your rocket is, the less you need to account for the atmosphere and the earlier you can spend dV on horizontal velocity.

[TK421d]

IDK what you people are smoking, but i cannot do anything with a rocket inside the atmo at all. 30° turn early on? there's no freaking way.

no design, no matter what Dv/TWR/fins/whatever does anything but flip end over end if you even TOUCH any controls before a height of 40k.

[Shpaget]

You're doing something wrong then.

Not 30° turn, but 1° turn, followed by another 1° soon after.

Try very gentle turns as soon as you can (<100 m/s vertical is perfectly soon enough). Keep your chevron (the yellow -v- mark on navball) inside the heading marker or at max outside of it by no more than a few degrees. If you have some active winglets, thrust vectoring and decent TWR, you should have no problem keeping stability.

[Gaarst]

There is a detailed thread about 1.0 LKO delta-v requirements:

http://forum.kerbalspaceprogram.com/threads/117494-100km-LKO-in-only-2800m-s-dV-Ongoing-Experiments

[Anquietas314]

no design, no matter what Dv/TWR/fins/whatever does anything but flip end over end if you even TOUCH any controls before a height of 40k.

Post some screenshots of your designs, but are you sure you're using nosecones and such with these rockets? Bricks don't fly too well in 1.0

[TK421d]

Post some screenshots of your designs, but are you sure you're using nosecones and such with these rockets? Bricks don't fly too well in 1.0

at the very least yes, nosecones or parachute cones, and even problems with fairings covering the whole thing.

hopefully when i get into 1.0.2 today it will be better. i honestly think my 1.0 install was bugged or something, it was THAT bad, ive seen others with problems: but nowhere near as bad as me

edit: OMG i can fly again... 1.0.2 is a life saver.

Edited May 2, 2015 by BobsYerUncle

[xandalis]

IDK what you people are smoking, but i cannot do anything with a rocket inside the atmo at all. 30° turn early on? there's no freaking way.

no design, no matter what Dv/TWR/fins/whatever does anything but flip end over end if you even TOUCH any controls before a height of 40k.

If you've been having that problem, you're probably starting your turn too late for a semi-realistic gravity turn. 100-150 m/s is the speed you should begin the turn, by about 5-10 degrees; maybe around 200 m/s if a rocket is really scraping the bottom-end of TWR at the beginning of the launch. I had no problems when following that guide, even in 1.0; although this is a habit I picked up from spending some time playing with RO/RSS for a while. Following that general guide also will make it easier to get rockets with lower TWR upper-stages into orbit, as they may not be able to pick up enough horizontal speed to reach stable orbit from a higher-altitude turn. I also happen to just like getting my periapsis out of the ground at least, during ascent, if not completely out of the atmosphere.

If you're using MechJeb's ascent guidance, I've found that setting the turn-start altitude to around 1.8km with a turn shape of 80-90% and turn end of 0 degrees works out fine for almost all my designs, although anything over a 1.9 TWR(SLT) needs to have a lower turn start than that. Or else it'll get flipped/torn apart during ascent.

[GoSlash27]

A decent DV budget for 1.0 was around 3,400 m/sec assuming you calculated it with vacuum Isp.

1.02 has increased the drag, so I don't know what the new DV budget is. Haven't looked at that yet because I've been working on spaceplanes...

Best,

-Slashy