Is it just me or is the DGIV not de-orbit compatable?

[unknown.exe]

Ok I am trying to de-orbit from the Mir. I use anti-normal to get my orbital path above KSC. Then I burn retro-grade
above the mid-Pacific to bring my PeR down to 5.600 M. But every time I begin de-orbiting (my heatshield is visable), I
get a 'hull-temp' warning, then a few seconds later KABOOM!!!! I have tried every thing from 90 degree bank and 0
degree pitch, to PRO104SPEC40. Every time I geu pwned by the atmosphere... any help?

[Urwumpe]

You are aware, that you use a far too steep reentry angle? 1.2° is the documented goal, if I remember correctly.

90° Bank is especially good for killing you during reentry, almost as good as 180° bank. And 0° pitch means you have nearly
no lift, but the sensible parts of the craft get more of the reentry heating as they can take.

Use 40° AOA and no bank until you have reduced your vertical velocity to 0 m/s.

[unknown.exe]

... so I should be at 1.2 degree pitch after my verticle speed is ? That makes no sense... I am trying to land not keep
going.... or will this eventually puch me below the atmosphere? What should I do when my verticle speed = 0? And
what should my bank be?!?

[Urwumpe]

OK, only for you:

READ THE DGIV MANUAL!

[unknown.exe]

Haha thanks... I DID!!!!!!!!
The instructions for the de-orbit checklist scenario only work with the original DG. I do the exact same re-entry procedure for both the DG and the DGIV... but for some reason it's only the DGIV that blows the hell up.



Post Edited ( 04-22-08 23:26 )

[Urwumpe]

No, you don't.

I don't know which instructions you follow, but what you write is not how you would reenter with ANY DG. At least when you
have any goals of keeping limits on the standard DG.

From the scenario instructions of the DGIV:

In this scenario you are docked to the ISS, undock, close the nose cone, turn prograde,  Target Cape Canaveral on the MAP
MFD and do the retro burn at 17.20M from the Cape until your reentry angle shows 1.2° (D2 to show reentry screen). Accelerate
time to  100X until your altitude shows 150km, Engage attitude reentry autopilot "PRO104SPEC40", and set your AOA with numpad
key "2" "8" so the vertical speed is about -70 M/S during reentry. (See "how it works" below). During reentry, switch to the
reentry disp lay on the flight computer ("D3" screen), and be careful to not exceed 1700C° nose temperature . Switch off the
autopilot at about MACH 2.5. If you have done everything right, you must be just above Cape Canaveral. Don't forget to deploy
the landing gear  and land smoothly.

What do you read when playing Orbiter? The Football results?

[Pirx]

It will probably help if you read a bit more carefully: reentry angle, not pitch. DGIV manual, not Orbiter checklist. And
for DGIV better try to forget anything you learned about reentry with the standard DeltaGlider. There are two tutorial
missions in DeltaGliderIV scenarios - one for the automatic and one for the manual reentry autopilot. They contain
very detailed instructions and explanations.

[SlyCoopersButt]

Don't forget to dump excess fuel before you begin to enter the atmosphere. Having too much weight could be fatal no
matter what entry you do. Use check vessel state before you enter the atmosphere. I am comfortable with no more
than about 50% fuel onboard with no cargo.

[unknown.exe]

Ok so it turned out that PRO105SPEC40 was perfect for me... but now I need to know some info... It seems that a precision
re-entry is a guess-and-check. Is there a certain way to calculate how far away from a base you need to be before the
de-orbit burn, and what your PeA should be lowered to? What are these values for a KSC landing? And thanks SlyCooper, but the
autopilot already tells you if the weight of the vessel is too much.

[Urwumpe]

You have to pilot the craft.

Sorry, but there is no precision reentry in real life and in orbiter. You can't do a perfect deorbit burn to just have to
glide without touching controls.

It is also no guess and check. If you know where you want to go, you can do it. Reentry MFD is a nice tool as it calculates
some important values in real time...

[unknown.exe]

Thanks guys! I was able to undock from the Mir, de-orbit, overshoot KSC by about half a mile, do a turn-around, and land
beautifuly on the main runway! I'll try that re-entry MFD... but I think I have an effective method now

[sunshine135]

Aerobrake MFD can help you more or less make a precision reentry, but what did we learn here:

1. Reading the manual is good, but understanding the manual is better.
2. You cannot drop like a rock and expect not to burn up in the atmosphere


The DGIV is a fine machine, and works well for testing your reentry prowess.

Cheers,

[James.Denholm]

unknown.exe wrote:
Thanks guys! I was able to undock from the Mir, de-orbit, overshoot KSC by about half a mile, do a turn-around, and land
beautifuly on the main runway! I'll try that re-entry MFD... but I think I have an effective method now

That's better than I've ever done.

[Urwumpe]

"Overshooting by only half a mile" just means you have not learned the right landing method. There had been a discussion in
the M6 forum some months ago, about the advantages of the HAC approach, like the Shuttle does. Practically, you fly a long
turn for lining up, while also dropping steeply.

It is pretty simple to fly with most winged crafts and it makes landing pretty easy as you can control your energy better.

The coolest HAC approach I ever did, visually, was a suborbital dynasoar ride. Pass over the Johnson Atoll (very beautiful
sight), observe HSI for the right distance to a VOR and then fly a nice ~250° turn. When you fly that turn right, you arrive
right in front of the runway with only little excess speed.

[McGlazd]

You ought to use BaseSynch MFD and its deorbiting program. Just put a reentry angle at 2°, an anticipation of 16,5° with an
altitude of 80km for a safe reentry on Earth.


MFD and tutorial on this page :
http://koti.mbnet.fi/jarmonik/Orbiter.html


You also can re-entry in the Earth atm anywhere, simply by using the reentry display of the DGIV (type D 2 on your keyboard to display your current reentry angle while deorbiting).

For a precise reentry for a safe landing on Cape Canaveral, there is the fabulous AeroBrake MFD for that. To use only once in the atmosphere.


Have fun and fly safe.



Message modifié ( 23-04-2008 09:39 )

[ar81]

If you use BaseSync MFD and Aerobrake MFD you might be able to deorbit and land on the runway without using main
engines.  I have done it several times.

[SlyCoopersButt]

There is one simple little trick I like to do at times with the DGIV or even other ships when I return to Earth, I deploy
the airbrake even when as high as 70 km to slow me down even faster than usual during re-entry. Don't think it's
very realistic but allows for some easy trimming of where I land if I discover I did not calculate my re-entry 100%
orrect and am slightly overshooting.

[Urwumpe]

Well, if the airbrake survives it, it is  legal - actually, creating more drag per kg spacecraft is a very good strategy, as
it reduces the heating. The inflatable heat shields developed by Russian and German companies work that way.

[SlyCoopersButt]

I have never came near the airbrakes kpa limit during re-entry. It's easy on the brake. Reducing heat is indeed one of
the things I like about doing it. Especially if I'm coming in with a heavy load. Inflatable heat shields? I've never heard
of them being a reality. I've only seen them proposed or in Sci-fi like the Leonov in 2010 which used airbags for aero-
braking in Jupiters atmosphere.

[Urwumpe]

Look for the acronym IRDT.

http://www.2r2s.com/irdt_concept.html

[GXE3]

The automatic reentry autopilot is crap (no offense). I use the manuel reentry autopilot which is much better. With
that autopilot you can set the Pitch (try to keep it above 20 degrees) and combined with the Aerobrake mfd, you can
make very accurate reentries.

Hope I helped.

[unknown.exe]

ARGH! More issues
I follow the DGIV tutorial sections "re-entry autopilot" instrustions and what happens is that I will have the the
periapsis dot (on the Map MFD) centered on KSC... I initiate PRO105SPEC40 at 150K altitude. But what eventually
happens is my periapsis drops down to Mexico! I have to initiate full thrust to even keep it near KSC! What is going
wrong?

[McGlazd]

The DGIV tutorials are not enough to learn a safe and precise re-entry. You are supposed to calculate your de-orbiting burn
with the SynchBaseMFD. You simply need to enter the correct parameters, such as the re-entry angle (2°), anticipation angle
(16,5°) and the reference altitude (80km). These parameters apply only for Earth. Any tutorials about SynchBaseMFD and
AerobrakeMFD are good enough to learn how to safely return from the space

[Urwumpe]

Also, you should remember that earth rotates once in 24 hours under your orbit. You will thus have one - two moments
everyday, where your orbit plane will pass over your target landing site. These moments are much cheaper for deorbit than
doing a stupid plane alignment first.

[unknown.exe]

Ok... the BaseApproach MFD that comes w/ the IMFD is for when you are far from the planet during a transfer. Where
do I get the SyncBase MFD?