I cannot reenter properly.

[Cobalt]

I've read concepts for atmospheric reentry, and I am completely incapable of putting the stupid thing on the ground where I want it. I can get it on the ground no problem. It's the location that I can't solve. I'm using BaseSync and AeroBrake. What tends to happen is I'll either overshoot or undershoot while I'm trying to get the AOA I want correctly. I got close a second ago, but I overshot and would have ended up in the ocean if I hadn't quit in frustration. Anyone have any tips on how to do it right? I'm willing to try in any spacecraft.

 

[Belisarius]

In my experience Aerobrake tends to underestimate the braking required. Try using speedbrake (B key on DG-IV, CTL-B on XR-5) in the last 400 km or so of approach. Keep practising! You can learn to control it just as you want to, with some practice.

 

[Cobalt]

My last attempt had me over the base I was hoping to hit still up 15 or so KM still. So I didn't even get a chance to get on an approach.

 

[TSPenguin]

Basicaly you adjust your AOA constantly according to AerobrakeMFD until you are slow enough to perform winged flight. Overshooting is not as big a problem as undershooting is, as you can turn around and approach from behind. This is how I do it with DG-like ships.

 

[Cobalt]

Under or over shooting it are problems. You severely overestimate my piloting skills. =) What's a good craft to learn on, the stock DG, DGIV, or something else?

 

[TSPenguin]

The stock DG is not able to hold the required AOAs without the patch that is on OH.
I recommend the XR1, but the DGIV will do just as good.


-----Posted Added-----


As Belisarius said can AerobrakeMFD not be trusted per se. So you need to constantly adjust your lift/drag to hit the target.
Then again there is experience which tells you when to make your reentry...

 

[Belisarius]

I recommend the DG-IV, the reentry autopilot is easy to control. If you find yourself overshooting at high altitude, kill the autopilot and then TWIST AND TURN. You'll lose energy fast. But then you have to worry about high G loss of consciousness...

 

[Goth]

I found useful to use retro-thrusters if I see that I'm overshooting the base.

 

[Gorn]

I use lower AOAs in the DG, 10 to 15 degrees, which works well; the only thing is it makes the reentry longer. I can set it to a higher AOA before hitting hard atmosphere then try to hold that attitude while digging a hole in the air. But it's very unstable, and if I lose that AOA I can't get it back and it's gone for good. IMO, if you plan on holding <parameter> = X, but you can't reliably set that parameter back to X if you lose control of the craft for a moment, then the plan's no good; you need to be able to actually *do* what you plan to do.

Here's my approach to developing reentries:

1) Start from the orbit you normally re-enter from. If you've got a "standard working orbit" it helps, things are just that much more predictable.

2) Wait or fast-forward until your path passes near your target base. Then, when you're *way* too far away from it, say just past the halfway around the orbit point, so Map MFD's distance to target base number has just hit its peak and started to decrease again, do whatever retro burn you intend to use in your reentry plan. Write down Map MFD's distance to target at the time you *start* the burn. Let's say that's 19000 km.

3) Do your reentry. Don't worry about getting to the target, you won't. Just do the reentry, using whatever AOAs, descent rates, etc. you plan to use. Keep your path on Map MFD pointed over the base, even though you're not gonna land there. Pilot the thing all the way to the surface and *land* it wherever it happens to end up, even if it's in the middle of the ocean.

4) After you land, look at Map MFD and get the distance to target number. Let's say it's 8436 km. Subtract that from your earlier number, 19000 - 8436 = 10564 km, and that's how long your normal reentry path in that craft is.

5) Do steps 1 through 4 again, just to make sure you're doing things consistently and get the same number for your reentry path or close to it.

6) Now, try your reentry when you're *that* far away from your target; in this example, you'd retro burn when Map MFD shows you're 10564 km away from the base. Then do the reentry just as you did earlier. You should come pretty close to the target.

Hope this helps,

Danny

 

[RisingFury]

As Belisarius said can AerobrakeMFD not be trusted per se. So you need to constantly adjust your lift/drag to hit the target.
Then again there is experience which tells you when to make your reentry...

AeroBreakMFD can be trusted just fine. What most of you are failing to see is that AeroBreakMFD is expecting you to hold 40ish° AOA right up until the ground, but you're actually not doing that. When you return to winged flight, your drag falls considerably, which means you're left with much extra energy.

My advice is to aim some 150 km before the base. Keep in mind, DGIV can hold around 15° downward angle and still fly.

My advice for a ship is DGIV.

 

[TSPenguin]

AeroBreakMFD can be trusted just fine. What most of you are failing to see is that AeroBreakMFD is expecting you to hold 40ish° AOA right up until the ground, but you're actually not doing that. When you return to winged flight, your drag falls considerably, which means you're left with much extra energy.

That is what I meant. It is a good thing for me, as when I go into winged flight I have enough energy to properly do final alignement and bring my speed down with the airbrake.
I also like to overshoot the base and fly a wide loop to align with the runway.
Or scare my passengers and dive straight down, generating some heat in the process. That'll teach them to question my pricing policies!

 

[Cobalt]

-snipping great advice-
Hope this helps,

Danny

Yes, this seems like a good plan. I'll start on it once I can set a defined start orbit, etc.

AeroBreakMFD can be trusted just fine. What most of you are failing to see is that AeroBreakMFD is expecting you to hold 40ish° AOA right up until the ground, but you're actually not doing that. When you return to winged flight, your drag falls considerably, which means you're left with much extra energy.

My advice is to aim some 150 km before the base. Keep in mind, DGIV can hold around 15° downward angle and still fly.

My advice for a ship is DGIV.

Good point, I'll undershoot on purpose and hope to cruise in.

That is what I meant. It is a good thing for me, as when I go into winged flight I have enough energy to properly do final alignement and bring my speed down with the airbrake.
I also like to overshoot the base and fly a wide loop to align with the runway.
Or scare my passengers and dive straight down, generating some heat in the process. That'll teach them to question my pricing policies!

They're just mad you don't offer them peanuts.

 

[TSPenguin]

They're just mad you don't offer them peanuts.

Peanuts in space?!? OUTRAGEOUS!:facts:

 

[RisingFury]

In my early days of reentries I used to align myself with KSC perfectly and then I'd end up with a 50° dive... I had to make sure to turn away from the runway and then towards it and also to keep maneuvering up and down to lose some energy to at least land at around 150 m/s.

Now I usually land at around 100 - 120. I know that DGIV is more then capable of landing at 80, but I like that extra bit of control and margin for error.

If you wanna bleed off some energy at the last second, you can go into a flare and then fly straight at the same altitude over the runway until your velocity and consequentially your lift drops.

 

[Cobalt]

Peanuts in space?!? OUTRAGEOUS!:facts:

Yeah, but people get peanuts on regular flights. They're gonna be expecting a peanut or two in space.

 

[mauzer]

try get slowly to the target then use hold altitude autopilot,then hover like an helicopter and make small changes with the hover and attitude,that's what I do and it works fine.