Summer break finally here and WHOAH back to square one (or two) learning KSP.

[LN400]

Now that my summer break is here, I finally have time to have a closer look at KSP after the update to 1.0.x.

Now, I do have a series of mods installed, so I'm not going to pretend I go stock. Just the way I prefer playing it.

Mods include:

FAR, KAS, KIS, KOS, RT, KWR, MRS, KER, Alarm Clock, Procedural Fairings, SCANSat, SpaceY Lifters, Infernal Robotics

The biggest change for me so far is the rework of how engines work, with variable thrust and reworked Isp, throwing me back quite a bit working out the maths for the designs. Not complaining, mind you. It's a challenge but it was overcome once (pre-1.0.x) and can be overcome again. The rockets flipping over isn't much of an issue anymore, rather it's another layer of fun having to give the design more thought. A question though: Any documents you will recommend for figuring out the new maths concerning a realistic delta v calulation for launches as well as documents on good design principles?

The new maths also include how to work out the gravity turn (with FAR installed) for a particular design. Any suggestions on documents greatly appreciated.

I guess that's it for now.

Oh, and how about you guys? Did it take long before you got back to it, launching without any major issues/worries?

[Streetwind]

FAR flies pretty much the same now than it flew before 1.0. Stock now flies pretty much like FAR flew before 1.0.

The one major difference that I found is that stock aerodynamics doesn't do well with low TWRs. My rockets simply don't fly straight up with less than ~1.5 initial TWR off the launchpad, no matter what. The exact same craft with more fuel in its tanks flies perfectly straight up with an initial TWR of 1.2 under FAR.

But for piloting, there should not be any practical difference between stock 1.0, FAR 1.0 and FAR 0.90. You put heavy things at the front, draggy things at the bottom, start your turn very early but turn only a little bit. Then switch SAS off and allow the rocket to tilt on its own, possibly reducing thethrottle if it tilts too slowly. You should be at no more than 60° by the time you pass 10km, but no less than 45°. After you stage for the first time above 20km, turn SAS back on and finish the turn manually as required.

How soon you start the turn and how aggressively you turn depends on your vessel. The more initial TWR you have and the more aerodynamic your vessel is, the harder and sooner you need to turn. The less TWR and more unwieldly, the later and slower you turn.

Also similar to FAR in pre-1.0 is the amount of dV you need to orbit. It really depends a lot on your vehicle and your ascent path (even more now than ever before), but it's about 1000 m/s less for Kerbin as a rule of the thumb. So, aim for 3500 m/s to orbit. Your engines have less Isp but you need less dV, so the resulting vessel should be pretty much the same size and weight.

As for your final question: as a regular user of FAR, I had no problems adjusting to stock... except when 1.02 rolled around and I discovered that annoying low TWR issue. I've since gone back to FAR because of it.

Edited June 11, 2015 by Streetwind

[LN400]

Thanks for the inputs. As for piloting, that's not much of an issue in itself. The G turn I'm still trying to figure out. It works in the sense that the rocket is turning but there is little to no way of predicing where I will end up. So far, it seems I best stay well away from 45* at 10km unless I want to level out at around 25-30km. The goal I'm going for right now is to hit 45* at around 30-36km, where I get max thrust, just to see how that works out. The maths is still elusive though. I did get pretty good results in 0.90 after a bit of hairy hocus pocus with the rocket equation but it seems I need to rework my formulas for 1.0.x. Thing here is, the wiki seems to be well out of date here unless I'm missing something.

[Terwin]

Thanks for the inputs. As for piloting, that's not much of an issue in itself. The G turn I'm still trying to figure out. It works in the sense that the rocket is turning but there is little to no way of predicing where I will end up. So far, it seems I best stay well away from 45* at 10km unless I want to level out at around 25-30km. The goal I'm going for right now is to hit 45* at around 30-36km, where I get max thrust, just to see how that works out. The maths is still elusive though. I did get pretty good results in 0.90 after a bit of hairy hocus pocus with the rocket equation but it seems I need to rework my formulas for 1.0.x. Thing here is, the wiki seems to be well out of date here unless I'm missing something.

Once I hit 35K, I try to get to 90 degrees asap(this is the point where aerodynamic stability and drag do not matter much, so I just accelerate to orbit)

Then again, I usually prefer my initial orbit to be in the 70-75K range so I can get maximum oberth effect when I do my burns to elsewhere.

Of course I often have difficulty getting a good gravity turn going early on, so I often have an appoaps above 60km when I hit 35km.

[Streetwind]

Oh, I don't do much maths for ascent paths, I generally fly by eye and gut feeling

This does require some test flights for new vehicles here and there when I misjudge how they will perform, but I usually have them down after 1 or 2 tries, and standardizing your building (always aiming for roughly the same TWR profile) helps a lot.

[LN400]

Reason I'd like to get the maths here is, I want to use KOS as much as possible, mimicking 'real' rockets on a gaming-for-fun level, meaning I don't think I'll attempt anything too realistic but I reckon automated ascents, insertions and so on should be possible with KOS. For that I need maths. It's going to need, literally, a rocket program with tests and more tests, but in small enough steps it should be doable with (hopefully) not too many disasters.

[LN400]

This one is new, or I never noticed it in 0.90 but it seems terminal velocity gets a bit funky between 8000 and 10000 metres. I mean, it raises steadily till altitude is about 8000m then it drops rapidly until altitude is around 10000m when it starts raising again.

Test rig:

Pod Mk I

Mk 16 parachute

Sounding rocket SRM-L (yeah I know, I'm traveling economy class)

First stage: 3xSRM-L (60% throttle)

Anyone else noticed anything strange about terminal velocity? Is there a plausible explaination for this?

[ElWanderer]

This one is new, or I never noticed it in 0.90 but it seems terminal velocity gets a bit funky between 8000 and 10000 metres. I mean, it raises steadily till altitude is about 8000m then it drops rapidly until altitude is around 10000m when it starts raising again.

Test rig:

Pod Mk I

Mk 16 parachute

Sounding rocket SRM-L (yeah I know, I'm traveling economy class)

First stage: 3xSRM-L (60% throttle)

Anyone else noticed anything strange about terminal velocity? Is there a plausible explaination for this?

What velocity were you doing at the time?

I think there is a change in the atmosphere's temperature curve above 8km, but it sounds like what you're seeing is the result of drag going up a great deal in the transonic region I.e. near mach one which is about 340m/s.

[Streetwind]

I can only wager a blind guess, but it might have to do with how fast you're going, and how KER calculates atmospheric efficiency/terminal velocity. For example, if KER bases the value off of the drag your vessel is experiencing, then there's a potential explanation: the 'sound barrier'.

That term isn't just for kicks and giggles; going supersonic is actually really hard, because of a phenomenon called wave drag that starts in the transsonic regime. KSP never modeled wave drag in the past, but it does now with its new aerodynamic model. Wave drag will hit your vessel like a wall, clinging onto it, making every m/s further a struggle to achieve, and many early planes just couldn't do it. Hence, 'sound barrier'. And then, after you manage to accelerate a bit further, it suddenly lets you go again. In fact, there's now less effective drag than even in the subsonic regime, and your vessel once more starts rushing forward.

So if you happen to be around 350 m/s between 8 km and 10 km, and drag experienced affects how KER computes and shows terminal velocity/atmospheric efficiency, then what you're seeing has nothing to do with altitude. It's just wave drag.

EDIT: Curses, ninja'd again!

[LN400]

Thanks tons, guys, really appreciated. While my speed was below 340 I can definitely see why it would happen. Again, thanks!

[Sharpy]

My rockets simply don't fly straight up with less than ~1.5 initial TWR off the launchpad, no matter what. The exact same craft with more fuel in its tanks flies perfectly straight up with an initial TWR of 1.2 under FAR.

Make a hovercraft with 1.01 TWR. Expecting it to stay perfectly immobile as it hovers up in the air is simply not viable. While gravity cancels out your upward thrust, there are no forces to counteract sideways "slippage". The same goes on with anything moving at speed insufficient for air drag/lift to start stabilizing it.

[Streetwind]

Make a hovercraft with 1.01 TWR. Expecting it to stay perfectly immobile as it hovers up in the air is simply not viable. While gravity cancels out your upward thrust, there are no forces to counteract sideways "slippage". The same goes on with anything moving at speed insufficient for air drag/lift to start stabilizing it.

That's the explanation that logic dictates, but not actually a solution. Empirical evidence shows the following:

1.) Build low-TWR craft in 1.00, launch it, it flies perfectly straight to 10km

2.) Build same craft in 1.02, launch it, it significantly veers off course as early as 2-3 km up, even with fins present and SAS on

3.) Install FAR onto 1.02, launch same craft again, it flies perfectly straight to 10km

If the cause for this issue was lack of stabilizing forces at low speed, then that means that something was changed in 1.02 that made rockets exceedingly unstable in comparison to other aerodynamic simulations available for comparison. There are clearly enough stabilizing forces available in the other situations. Why not in 1.02?

So, since I personally tend to favor low-TWR designs, I decided to switch to FAR, where those fly properly - much like in RL. But for someone who likes their rockets to leap off the pad like a bat out of hell (or an ESA rocket ), that would not be necessary, because those already behave properly in stock.

[LN400]

About aero modelling in stock vs FAR: I had to remove FAR for the sounding rockets. I've read up on how the two mods don't play well together and I can personally vouch for that being the case. Stock, all fins work (balancing the rocket is another story entirely), in FAR, the fins don't seem to work very well, the small fin doesn't work at all. Another thing is, I've read how people slant the fins for spin, to stabilize but here, in stock and in FAR alike, spins be it fast or slow do bugger all for stabilizing.