Flight Question Re-entering XR2

[Lazers]

I've tried every tutorial I can think of, all the reentry MFDs, and still this thing eludes me. I cannot re-enter the XR2 down to a base. I can do it with non heat sensitive spacecraft, just the Ravenstar gets far too hot. How is it possible? Burning on the other side of the earth doesn't work, placing the 'impact' marker on MAPMFD doesn't work. AerobrakeMFD just screws it up further, giving me crazy Gees. HELP.

 

[ex-orbinaut]

Sounds like you are going in too steep. Lower your Periapsis into the atmosphere (to about 30 km or so), but don't put int into the ground. The atmosphere will see to slowing you down. You are clear on how to control the rate of descent with angle of attack? Try not using too high a rate of descent (certainly never above 100 ms, for sure), and start the reentry from 55 - 60 km altitude, somewhere around 3000 km distance before the base where you plan to land.

At least that is what I do, and don't have any problems.

 

[dgatsoulis]

Check out these tutorials:

[ame="http://www.orbithangar.com/searchid.php?ID=3660"]Home Direct[/ame]

This a nice one that teaches you how to make a direct reentry with the XR2 from the moon (No orbit insertion burn required)

For something easier (Simple reentry) have a look at this:
[ame="http://www.orbithangar.com/searchid.php?ID=2453"]DGIII Reentry Playback[/ame]
This one is for the DGIII, but it also works with the XR series.
Just make sure you have the DGIII installed.

Hope these help.

Happy orbiting.

 

[Sky Captain]

Make sure XR2 are not too heavy. Although it is possible to reenter with overloaded craft if you do it carefully it`s far easier when ship is light. Start from low circular orbit some 200 - 300 km high. Dump the HAB module and most of the fuel leaving only some 5 - 10 % in case you miss the runway. do a retro burn till your perigee drops to 30 - 40 km altitude. When you come below 120 km altitude close all hatches and radiator, at 100 km altitude engage attitude hold autopilot at 40 degree AOA. When you hit the atmosphere watch the vertical speed and vertical acceleration. Adjust the AOA to maintain roughly 100 m/s vertical speed and you should reenter fine.

---------- Post added at 07:09 PM ---------- Previous post was at 06:42 PM ----------

When deorbiting from low orbits like ISS and such you can just set your perigee at 30 km switch on the attitude hold autopilot to 40 degree AOA and just sit back and watch. The XR2 will reenter fine all by itself provided it`s not too heavy.

 

[the.punk]

Yes. Don't put ypur periapsis into the ground. Also AerobrakeMfd gives you the max G-acceleration. Don't let it become green because then your reentry angle is too high.

 

[Lazers]

Yes, i can *reenter*. Just, not to a base. Re-entering to any old place is easy.

 

[ex-orbinaut]

Yes, i can *reenter*. Just, not to a base. Re-entering to any old place is easy.

One word, then.

Practice.

Thinks it is how most of us got the kanck of it. Good luck!

PS: Do one of your normal re-entries to no particular place and see what distance you use up slowing down, then use that distance from the base in future.

 

[Sky Captain]

You can try this way: find a base which your orbit crosses and set it as target in map MFD. When you are directly over the base do a normal deorbit burn, reenter and land (does`t matter where) and look what distance map MFD shows. Next time use this distance to know when to do deorbit burn. For example you landed 10 000 km from base. Now use this distance to know how far from target base to do a deorbit burn.

 

[dbeachy1]

I use BaseSyncMFD to calculate my deorbit burns; you can download it from the bottom of Jarmo Nikkanen's add-on page here. Set your reentry angle to between one and two degrees (I usually set it to one degree) and then experiment with the other parameters.

 

[Shadow Addict]

I recommend Aerobrake's map to monitor your descent. I use this with the XR-series' attitude hold AP and it always gets me to within 100km of my target (though that's due to my inexperience).

 

[Tommy]

From the sound of things, I'd say you aren't doing the De-Orbit burn correctly, and are coming in too steep. First, consider when to perform the burn - and remember that too soon is much better than too late. The altitude of your current orbit affects this, the higher you are, the sooner you need to burn. From a low parking orbit of ~200k, burning 14.5M from the target is fine. Coming in from a higher orbit like the ISS's orbit you'll want to burn at least 16.5M from the target. 17M to 18M is better, but you can de-orbit up to a full orbit away and make it. Burning opposite the target is probably the easiest, as you get a nice gentle ReA (will be less than one degree), and a bit of a "rollercoaster" up and down glideslope.

Second, consider what PeA you desire. The later you de-orbit, the lower this needs to be. For a longer, gentler ride you'll want a PeA of about 50k if de-orbiting half way around the planet.

Keep in mind that AerobrakeMFD doesn't consider aerodynamics until you are under 200k, I usually start orienting the vessel for re-entry at 150k. Use the <MOD> and <PRJ> buttons to get the planet map display, and pick an AoA and bank that result in the green line showing your predicted trajectoy to end a bit short of the target. Anywhere within a couple hundred kilometers is fine at this point. The "Dist to base" shown is the distance between the end of the line and the center of the base.

If Aerobrake shows you on target with an AoA of less than 40 degrees, you can pretty much ride it out with small adjustments to keep the target aligned - remember that it's best to keep things a bit short at first. It's easy to extend the glide later, if you have to shorten it you'll get into heating problems.

The Home Direct tutorial mentioned above shows how I manage all that. From the point where I'm down to suborbital speeds and turn upright it's a pretty standard re-entry. You can watch the AoA indicated in SurfaceMFD to see the small changes in AoA. You'll also see how I offset the target so that I come in a bit to the south of Canaveral so I can make a 270 degree HAC turn onto my runway alignment.

Other than that, it's just a lot of practice. I've flown hundreds of re-entries to get to the point where I can usually nail a deadstick landing.

 

[Arrowstar]

I recommend Aerobrake's map to monitor your descent. I use this with the XR-series' attitude hold AP and it always gets me to within 100km of my target (though that's due to my inexperience).

I do this too. Once you pick up some experience, the MFD can put you right on top of your airstrip with just enough energy to come around and put yourself down on the runway. Practice makes perfect!