Anybody have this figured out?

[Charley575]

Ok, so I've played a lot of KSP, but there's one thing I still can't get right. How to determine the impact point of a reentry vehicle on bodies with atmospheres, particularly when using a more traditional, shallow reentry profile, as opposed to a steeper, "direct drop" profile. Are there any mods out there that take into account the planet's rotation, time to entry interface, the initial velocity at the interface point, and the ballistic flight characteristics of the entry vehicle to plot an approximate impact point, or does anybody have quick, easy way to plot it manually?

[HebaruSan]

This mod gives predictions (look for the red X on the map), but it's not been hugely accurate for me in 1.0.5. I assume that's because the new aerodynamics are so complex.

 

[softweir]

MechJeb also gives atmospheric landing predictions, and you don't have to use the autopilot features if they feel "cheaty" to you.

Edited January 26, 2016 by softweir
Typo!

[Johnny Wishbone]

Well, I imagine shortly that this thread will be full of replies telling you to install MechJeb and let the game play itself for you. If that's "fun" for you, then go nuts.

 

Personally, I prefer to eyeball it and use quicksaves. Experience playing the game has given me a general idea of where to begin re-entry if I want to land at a certain area, but a lot of that also has to do with the craft. If you have a basic capsule and/or something that's designed for ballistic re-entry, then you pretty much have one chance to hit the mark. If you're long, revert to a quicksave and re-enter sooner. If you're short, revert and wait a little longer. If your craft has lifting bodies or wings or some manner of propulsion, you can control your re-entry a lot more and make up for any deviations. The fun for me is figuring all that out for myself via trial and error, not using a mod to do it for me.

[Red Shirt]

With the old souposphere MJ could drop a ship almost on the mark. You often had to compensate for this when sending a rescue mission, less a second rescue mission be needed. In 1.0.5 with MJ a close landing at KSC might be in the ocean to the east or in the rough grass on the KSC side of the western mountains. Yes, that's close enough for career (so I've been told as I personally never play career), however you better send a rover if you need to be exact. Point is, eyeball and skill is still required to land closer.

[Vermil]

Take notes while practicing/testing and take care to be consistent. (Actually, this is sort of how science originates.)

Circularize the orbit at a low altitude, just above the atmosphere. Note the altitude.

Use the navigation node to plan a braking maneuver. Plan a specific amount of m/s. Note the m/s.

Move the navigation node about until the descending curve points at a recognizable target.

Now for the tricky part. When you hit the navigation mode, burn as exactly as you can the planned amount of m/s brake in retrograde. Ignore the indicator scale on the navigation node. Just keep track of the numbers, the m/s. And then cut the burn.

Check where you land. Try grasp some measurement of how far you are from your original target. Note this measurement. (I use relativity to geographical features).

 

Using this method, which I train during shameless quicksaving/quickloading with an unmanned test-mission, I then have enough info to hit land every time.
Problem is that I have only worked it out for strictly equatorial orbits, which limits the landing spots.

 

Edited January 26, 2016 by Vermil

[bewing]

As said above, adding aerodynamic lift and control surfaces to your RV, and then flying it as it glides down unpowered is what lets you pinpoint your landings. It also eliminates almost all reentry heating problems. But it takes a lot of design work on your RV, and some practice to scrub off approximately the right amounts of speed at the right times.

But I have some parts that reenter -- and there is absolutely no way to precalculate where (within 10 km) they will land, because they are designed to be aerodynamically inefficient.They tumble, they porpoise, they glide, they spiral, they spin. So I don't think there is anything that can give you a definitive X on the ground.

 

[Nich]

Yes this just takes a TON of practice.  You can however have some control even with a rock falling out of space.  Steamline for more distance and fatten it up to fall shorter