best ascent profile 1.1.2

[nater662]

What is the optimal ascent profile in 1.1.2. I know this change in 1.05 but I have taken some time off and now getting back in. 

The old Delta V maps put orbit of kerbin at around 4500. However some of the newer maps I see put it as low as 3200! 

I can do it now at about 4300 or so doing a 5-degree turn and keeping under 200m/s until 10K meter, Then slowly going to 90 degrees and full speed after 10K. (the way Manley used to say) but how on earth do I get to the 3200? Space plane?  

Edited May 5, 2016 by nater662

[Empiro]

You're working with very old information, ever since the Aero update, the process is:

1.3 TWR on the pad. Fly up until 50 m/s, pitch to the right 5 degrees. Follow the prograde marker as it slowly drops to the east. You know you did it well if you hit 45 degrees at 10-14 km. Keep following until AP is at desired height, and coast.

It usually costs a bit more delta-V with the low-ish TWR I like to use, but you start out with more delta-V because of the extra fuel you're carrying.

[FullMetalMachinist]

32 minutes ago, Empiro said:

You're working with very old information, ever since the Aero update, the process is:

1.3 TWR on the pad. Fly up until 50 m/s, pitch to the right 5 degrees. Follow the prograde marker as it slowly drops to the east. You know you did it well if you hit 45 degrees at 10-14 km. Keep following until AP is at desired height, and coast.

It usually costs a bit more delta-V with the low-ish TWR I like to use, but you start out with more delta-V because of the extra fuel you're carrying.

^ This, with a small addition, since the OP specifically mentioned staying slow while under 10km.

With the new aero model, it's really hard to hit terminal velocity on ascent. You pretty much never want to throttle down your engines on the way up, even if you start seeing flames. Flames do not mean that you're going too fast and fighting drag too much. They just mean that you're going fast enough to get hot. You should only be worried if parts start getting close to overheating and blowing up. 

Also, your starting TWR and the TWR of the second stage usually dictate when and how hard to make your first turn. Generally, a higher TWR means turn earlier and harder (but expect more heating on the way up), and a lower TWR means turn later and gentler. 

[nater662]

Thank you both! I have been looking for better information on this but could not find it! 

Any advice on space planes accent? Did it change a lot too? 

1 hour ago, FullMetalMachinist said:

^ This, with a small addition, since the OP specifically mentioned staying slow while under 10km.

With the new aero model, it's really hard to hit terminal velocity on ascent. You pretty much never want to throttle down your engines on the way up, even if you start seeing flames. Flames do not mean that you're going too fast and fighting drag too much. They just mean that you're going fast enough to get hot. You should only be worried if parts start getting close to overheating and blowing up. 

Also, your starting TWR and the TWR of the second stage usually dictate when and how hard to make your first turn. Generally, a higher TWR means turn earlier and harder (but expect more heating on the way up), and a lower TWR means turn later and gentler. 

 

 

1 hour ago, Empiro said:

You're working with very old information, ever since the Aero update, the process is:

1.3 TWR on the pad. Fly up until 50 m/s, pitch to the right 5 degrees. Follow the prograde marker as it slowly drops to the east. You know you did it well if you hit 45 degrees at 10-14 km. Keep following until AP is at desired height, and coast.

It usually costs a bit more delta-V with the low-ish TWR I like to use, but you start out with more delta-V because of the extra fuel you're carrying.

 

 

[Chaos_Klaus]

Well, the aero overhaul was back in 1.0 and that is about a year in the past. Nothing significant has changed in 1.1.2. in that regard. 

You probably fly too steep a trajectory and are going too slow. You should fly a gradual arc reaching 45° at 10km and flattening out even further. The goal is to never deviate from your prograde vector too much, because that is what creates a lot of drag. Ideally that means flying a gravity turn with absolutely no control input. For that however you need your pitch maneuver to be perfect and it's not worth obsessing about this. Doing corrections during ascent is fine really.

 

Limiting speed is also not necessary. The only thing to remember is that between 270m/s and 340m/s is the transonic region before passing the soundbarrier. In that region of speeds you will encounter more drag. Once you pass the sound barrier, you are encountering less drag actually. So try to point exactly prograde while you are between 270m/s and 340m/s. One thing you can do is to punch through the sound barrier on SRBs early on. 

[numerobis]

21 hours ago, nater662 said:

Thank you both! I have been looking for better information on this but could not find it! 

Any advice on space planes ascent? Did it change a lot too? 

Compared to 0.90, it's changed quite a bit: first, jet engines can't take you to orbital velocities, so you really do need to have rockets to round out the atmospheric flight. Second, jets have much more complicated thrust characteristics.

You need to go supersonic at modest altitude (under 10km) and then you begin to gain more thrust than drag as you speed up. That's the point where you want to start climbing; a common figure is a 30-degree pitch. Probably a shallower pitch would do better, but there's a risk of melting your cockpit if you climb too slowly and gain too much speed at low altitude.

[Plusck]

On 05/05/2016 at 4:35 AM, Empiro said:

You're working with very old information, ever since the Aero update, the process is:

1.3 TWR on the pad. Fly up until 50 m/s, pitch to the right 5 degrees. Follow the prograde marker as it slowly drops to the east. You know you did it well if you hit 45 degrees at 10-14 km. Keep following until AP is at desired height, and coast.

It usually costs a bit more delta-V with the low-ish TWR I like to use, but you start out with more delta-V because of the extra fuel you're carrying.

 

On 05/05/2016 at 5:15 AM, FullMetalMachinist said:

^ This, with a small addition, since the OP specifically mentioned staying slow while under 10km.

With the new aero model, it's really hard to hit terminal velocity on ascent. You pretty much never want to throttle down your engines on the way up, even if you start seeing flames. Flames do not mean that you're going too fast and fighting drag too much. They just mean that you're going fast enough to get hot. You should only be worried if parts start getting close to overheating and blowing up. 

Also, your starting TWR and the TWR of the second stage usually dictate when and how hard to make your first turn. Generally, a higher TWR means turn earlier and harder (but expect more heating on the way up), and a lower TWR means turn later and gentler. 

And to add to that addition:

I like to have a higher starting TWR - somewhere around 1.7-1.8. With that, and with a decent TWR on the second stage, that means about 10° by 100m/s, and 45° at around 8km. Typically this gets to orbit for a total of around 3400m/s, or less if there is very little drag (which for me is just about never!).

[nater662]

On 5/5/2016 at 10:26 PM, nater662 said:

Thank you both! I have been looking for better information on this but could not find it! 

Any advice on space planes accent? Did it change a lot too? 

 

 

 

I finally got a chance to test this. I Did it with about 3600 with a not very aero dynamic rocket! Much better than the 4300 I was doing before. That should save me a lot of kredits. 

And thanks on the Space Planes advice.