Flight Question Re-entry question

[Joepvermaak]

Hi everyone,
I am back after a few years and this time i am determend to master the art of reentry. However. I want to make a reentry from lower orbit. About 222 km, I got BaseSync within 14 km, and Airobrake seems to be fine too... Still something is going wrong: :sos:

Sometimes i bounce of the atmosphere, or my reentry is to steep and i need to land somewhere near hawaii.. My AOA is 40, i aim for 10 km PeA (as any higher numbers fling me to the other side of the planet) and vertical speed between 80 and 90.
Can someone give me some orbinautical advise?
I know..practice, practice, but i need to put those wheels on the airstrip of KCS!

 

[garyw]

Why is your AOA 40 degress? It may work for the shuttle but doesn't work for every vehicle.

Also are you banking at any point?

When I entry I tend to go for 30 AOA which I do change during entry and aim for 60KM PEA and use S-turns to manage the descent rate.

 

[Joepvermaak]

Hi,

If I aim for 60 Km, I bounce off the atmosphere. Therefore i thought to go in steeper. I'll try the 30 AOA, but then one looses less speed.

I'll let you know..

Regards,

Joep

by the way: i am working with the DGIV-2

 

[garyw]

Try the DG-IV entry autopilot, see how it does it.

Losing less speed is not an issue if you keep descending, you just need to start your entry further back. I always start around 170 degress away from my target landing site.

 

[Joepvermaak]

Ok, so this means that i should not do my de- orbit burn on exactly the other side of The planet relative to the landing site, but a fraction later?
I have been using the auto pilot. Default it gives a 40 AoA. I Will try this on à 30 degree aoa, see what it does.

 

[Urwumpe]

Ok, so this means that i should not do my de- orbit burn on exactly the other side of The planet relative to the landing site, but a fraction later?
I have been using the auto pilot. Default it gives a 40 AoA. I Will try this on à 30 degree aoa, see what it does.

More lift, but also more heat on the wrong places. Keep 40° AOA, but use bank for managing your descent. By banking more to a side, you increase your vertical velocity downward, by flying more level, you increase it upward. The fun part is now, that deceleration and heat both depend only on your vertical velocity. The faster you loose altitude, the hotter it gets and the more speed you loose. Thus, by managing your descent rate, you manage how fast you slow down and how hot you get.

I aim for 16 m/s² deceleration with a DG type vessel,

The S-Turns are only for keeping your spacecraft trajectory towards the spaceport, since flying banked always means you do a curve. The 10.5° relative azimuth to the landing site of the Space Shuttle works also well for the DG: If you are flying in a direction that is 10.5° away from the direct great circle direction to the landing site, you invert the side at which you are rolled (80° bank left becomes 80° bank right), until you are 10.5° away from the direct direction on the other side.

This automatically guides you to your landing site, and at 16 m/s² deceleration, you should be slow enough for a landing then.

 

[Keatah]

pffaggghh!!! All these numbers and procedures and autopilots! All you need is a view out the window..

 

[Joepvermaak]

And we have touch down!!! I overshot a little bit, but was able to make a circle and pick up the ils. I was deceived by the message; no re-entry at this time, however a re- entry did occur. I did use 40km as lowest point. Thank you all for giving me some valuable info