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[Robsoie]

20% fuel reserve to be safe sounds right but it may depend on your ship.

Usually with a XR-2 (i don't know much about xr-1 and xr-5 regarding realistic loadouts) and default settings to be safe i'll always try to get there with at least 30% main engine fuel left for a re-entry, but usually you need less.

You will burn fuel only during 2 times :
-aligning your orbit with your targetted base.
For this use Base Sync MFD available at the end of this page, it's a real must have.
This way you'll see which of your incoming orbits will be the closest to your target.
And you'll be able to even lower that difference by using the normal + and - autopilots and burn to align better.

-the retrograde burn that will project your ship down to Earth, ideally to your target.
Do not start burning too close to target or you're going down like a brick and will burn in atmosphere (with default ship settings, as it's possible to edit the preferences and cheat a bit regarding this).
You can use the Map MFD for this (adjust then with your Translation RCS) , but for precision re-entry with the retrograde autopilot (and so wasting much less fuel) Aerobrake MFD is the best bet, but it's a bit complicated and need tutorial readings.

Once you're set , you should then have no more use of the main engine, ou're going down like a glider by sing the atmosphere to slow you down.
Sparring then more fuel in case you will need it after overshooting or undershooting your targetted base.

In Orbit, with the XR-2 deploy the radiator, so your slowly increasing temperature will be kept low enough. Then turn off the APU (the APU fuel is going down quickly and will not live for more than 3 or 4 orbits)

Before hitting the atmosphere turn on APU if it has not been done automatically (at a specific altitude it turns o) and close your retro-doors or you're going to say goodbye to your ship too.

[sluissa]

Robsoie probably has a much better method, and I'm going to give aerobrake mfd a look tonight, but when I'm just eyeballing it, I'll try to align my orbit with the base using normal +/- autopilots and burns and the map mfd, and then when I'm about 180 degrees(+/- 10 depending upon my orbit altitude) around the planet from the base I'm aiming for, I'll do my burn to lower my orbit to around 60 km over the base. I'll use the attitude hold autopilot with the XRs or the reentry autopilot with the DGIV and control the settings myself. It's a bit different from normal atmospheric flight, but nose down during reentry actually increases lift, while nose up makes you fall faster. A neutral angle is about 35 degrees usually, but adjustments always have to be made as you descend, lest you descend too fast and burn up, or raise too high and overshoot your target, or even hop out of the atmosphere, leaving you on a bad course to come back in at a VERY steep angle that can easily be dangerous.

It's not ideal, but it's gotten me to within 200 km each time. Only a small use of engine is required usually. Moreso on the overshoots than the undershoots, since turning around is very wasteful with your speed and altitude.

[Carrion]

Good good.  So +/- APs to adjust the orbital path; I will have to experiment with this.  I am a bit distracted now with some other things but I will try to get a flight in tonite and I will try to make a landing from orbit using all of this new info and the Base Sync MFD.  Quickly though, Robsoie, you said to deploy the radiator and kill the apu, but must I stow the radiator before re-entry?  It seems like it would rip off from the friction.

[sluissa]

Good good.  So +/- APs to adjust the orbital path; I will have to experiment with this.  I am a bit distracted now with some other things but I will try to get a flight in tonite and I will try to make a landing from orbit using all of this new info and the Base Sync MFD.  Quickly though, Robsoie, you said to deploy the radiator and kill the apu, but must I stow the radiator before re-entry?  It seems like it would rip off from the friction.

Yes, stow it before reentry. Turning off the APU is just to save APU fuel on the XR series. If you're not careful you'll run out completely and lose all of your hydraulics. Nearly all of which are pretty important.

The radiator is just important on the XR series as well because they simulate heat build up in the coolant system. If you're not on the ground and connected to a external cooling supply, or in space with the radiator deployed, you're building up heat. Heat is bad in this case because your computers will shut down with too much of it. Not only do you lose a lot of important data, but you also lose your life support. Go too long without active life support, and well... results ain't pretty. In my experience there's plenty of time to get from the ground and into orbit before your heat begins to get into the warning levels. However, reentry seems to be a bit more tight with the time limit. I'm almost always into the yellow, and occasionally the red before I'm on the ground. I can usually get into orbit safely before I"m into the yellow.

I suppose if you wanted to be realistic, you'd stow the radiator before any sort of high thrust burn (anything other than RCS). But I personally don't. Thrust doesn't tend to cause that many G's on the craft anyway. Most of them max out at about 1 G of thrust so I don't think there's that much stress on it. I think I just got nearly 2 G's using the scramjet of the XR5, but that was still in atmosphere anyway so the radiator wasn't even a concern at that point.

Another note on the XR5. I was correct earlier when I thought that it was the exception to the rule that crafts had enough thrust to lift themselves straight up. My last takeoff, with a full payload in the XR5, I couldn't nose up more than about 30 degrees without losing speed.

[Carrion]

I figured that was the case with the radiator.  In fact, I went and read through the pre-re-entry check in the XR5 computer and it mentions the radiator there.  Good, it makes sense, but I wasn't sure because of the enormous amount of heat that is built up in re-entry.

I used the base sync to some success.  With really being sure of what to do, I figured out how to decrease the relative inclination and close the distance.  I also sort of figured out the DeOrbit screen.  When the time came, I attempted my retrograde burn and everything looked perfect: the orbit was passing down to the surface and it looked approximately right in the map MDF.  Then I turned pro-grade to wait for re-entry, in the mean time activating the attitude hold AP.  For some reason, after that, my descent went way off course and I think it may be because of the AP, but I am not sure.  In trying to correct the descent I turned retrograde, burned and tried set it up again, but ran out of fluid instead, main and RCS.  Still facing retrograde, my ship hurtled into the atmosphere and, well, burned up.

I am curious about this nose down = lift strategy and hopefully soon I can get a ship in position to try it.  Sluissa, by 35 degrees you mean on the surface HUD ribbon?  That would be nose up... right?

[postal83]

Ultimately, re-entry is the hardest thing to execute.  with the DG-IV, reentry is really only possible using the the autopilot.  However, it's possible to use the glitch where u open the glass cockpit, then set the atmospheric mode, but the main issue is trying to adjust the AoA manually is almost un-doable because the autopilot automatically adjusts the center of gravity, shifting fuel aft and backwards automatically which you can't really do manually.

The most important MFDs are Aerobrake, Basesync, and Launch MFDs.  They make life  800X easier.

Also, once mastering the DG-IV, the XR-2/5 are much easier to learn.

[sluissa]

Sorry if I was unclear about the nose down= more lift thing. You should almost never have your nose lower than about 10 degrees over the horizon on the surface hud/mfd during reentry. However, this position will provide the most lift. Between 40 and 60 degrees nose up, you're causing more drag than lift and you'll fall faster. You probably don't want to go more than 60 degrees nose up, although there are exceptions. The XR attitude autopilot simply won't let you. You want to aim for a descent rate between -1 and -100 m/s so watch your hud/surfacemfd for your descent rate. You can tend to drop a LITTLE faster, but I find that anything over -150 is putting the heat dangerously high and I soon have to lower my descent rate, or even climb a little for a short bit.

Lowering your nose will also tend to increase the heat on the leading edges and top of the craft for a short bit before the lift compensates. Raising the nose will focus the heat more on the belly, but soon the descent rate will overcome this if you're not careful. This was the big mistake I made my first few reentries. I focused on protecting the top of the craft, knowing it was more vulnerable, but this ended up dropping me too fast and it became too much for even the heat shield to take. I thought lowering my nose, thus increasing the heat for a short while, was hurting. Rather, it was what I should have done. Big thing is don't let the heat build up to near critical levels, because if you do want to slow your descent, the heat will get worse before it gets better. Leave yourself a safety margin.

Also, yes. Postal is right. trying to do a reentry without SOME sort of autopilot assistance, even if it's just to keep a set angle is just an exercise in punishment/near impossible.

[Robsoie]

I wrote a tutorial about Aerobrake, while applying it myself so i describe my actions and use screenshots, this way it should be very easy to understand even for a beginner .

Needs :
XR-2 Ravenstar
http://www.alteaaerospace.com/

Wideawake International (Ascension island)
http://www.orbithangar.com/searchid.php?ID=3666

Base Sync MFD
http://koti.mbnet.fi/jarmonik/Orbiter.html  (bottom of the page)

Aerobrake MFD
http://www.orbithangar.com/searchid.php?ID=2139

(Note : activate the MFDs in the "Modules" section of the Orbiter launcher
If you have more MFD than 1 page of the MFD display list, click on the Select button to go to the next MFD list page to see more of them)


- Load the XR-2 Ravenstar "Docked to ISS" scenario.
Being docked to ISS, means you're at an orbit of 358 / 371 km altitude.
Press the H key 2 times to have the Surface Earth HUD (allowing to see the speed and altitude in km).

- In the MFD select the Base Sync one. click on the TGT button.
Type manually (unlike other, there's no drop down menu to select it directly unfortunately)

Code: [Select]

Wideawake International

We can see in white the 5th orbit is the one that will be the closest to KCS, so the one that will have us wasting the less fuel to align.

NOTE : You can see 2 squares on your orbit in this MFD (the green line is your position) :
the empty square is the Descending Node, in this one we'll use the Normal+ autopilot.
the white square is the Ascending Node, in this one we'll use the Normal- autopilot.

- Undock from ISS
Start the APU, then close the Nose Cone
Wait until it's closed and Turn the APU off again.

-Wait until the XR-2 is near the descending Node, go with the Normal+ autopilot and burn until you're below 200k in the Base Sync MFD.

-Wait now until the XR-2 is at the Ascending Node, go with the Normal- autopilot and burn until you're as close to 0 as possible (be sure to be in Translation RCS mode instead of Rotation, this way you can fine tune with Numpad 6 and Numpad 9)


There by example it means my 4th orbit will be only 37 meter close to Ascension Island, that's great.
Now wait until you're at the white orbit.
At the Ascending Node (Normal - autopilot) make another correction in case this orbit moved a bit too much away for you from the target. But it should be good as long as you made your normal correction at those 2 nodes and not anywhere else it should not have changed much.

-on the MFD the yellow line is Wideawake International, our target.
We will burn in retrograde from the opposite side of the world in comparison to that yellow line.
So before we're there, it is time to use the Aerobrake MFD.

Bring the Aerobrake MFD and click on the TGT button. and like for the Base Sync, type manually and press enter :

Code: [Select]

Wideawake International

The grey line is what we will move when we will make our rentry retrograde burn.
The goal will be to have the grey line exactly where the yellow line is.
At some point during the retrograde burn , the display will "jump" , don't worry it's normal.

-So for now wait until you're at the opposite side of the world from the yellow line.
Once you're +/- there, use the Retrograde autopilot and then burn
At some point the display will jump as i said, then burn more carefully.
In the end , being in Translation RCS mode instead of Rotation RCS mode, you'll use Numpad 6 and Numpad 9 to adjust, the goal is to have the grey line in the same location as the yellow one.



Seems OK.

-Bring back the Base Sync MFD, you will notice the distance between our Orbit and Wideawake International increased during our retrograde burn.
So at the incoming descending node, use the Normal+ and burn/adjust to lower this distance (remember to fine tune with the RCS). There i lowered it +/- like it was in the previous correction


-Now move to Prograde autopilot
Once the XR-2 is fully in prograde, click on the Attitude Hold autopilot.
With numpad 2 and Numpad 8 adjust so our angle of attack is at 40


-Use now the Aerobreak MFD
You will notice the grey line is not anymore exactly on the yellow one, don't worry about this.
Press on the PG button
Press on the PRJ button , this display will appear :


See on the grid, the center is Wideawake, the green line is you, according to the current display you will overshoot Wideawake.
But do not worry, it's not yet adjusted to our attitude, but it will do it progressively the aiming will come back on Wideawake :


During the fall, adjust the Attitude Autopilot to keep the aiming square near Wideawake by using the 0.5 increments/decrease to keep this aiming close to the center :


Important : never ever do more than X10 acceleration time, and even better do not use acceleration time at all, there's nothing better to screwup the internal calculations of everything that is going on during a re-entry.

-At some point (+/- 90 km altitude) the APU will autostart.
Now is a good time to close the Radiator, or the XR-2 will not survive when it will go below 60 km.

At 90 km it is a rather critical time for all the internal calculation (atmosphere, angle, friction slowing you down, autopilot etc... ) it is better to not accelerate time anymore or you can end very very badly.

If you managed well with the 0.5 increment/decrease for the attitude, your aiming should always be good and near Wideawake International.
And you have always +/- 40% of fuel left.

At 70km you should be at +/- slowed to mach 24
At 60km , +/- mach 21
At 57km, you should see the shields beginning to heat up in external view and soon enough you should have magma some fiery descent.

At 55km we should be at +/- mach 19
At 50 km you should have been at mach 17 and will be burning more.

Don't worry about the temperature of the hull despite our fiery re-entry, our planning and  trajectory IS good, so the temperature will never get too high, the shielding will resist.
At 45 km we're at mach 14 , the atmosphere is slowing us very nicely
At 40km we're at mach 11
And as you can see, we're doing good in the Aerobrake MFD

The white dot is us as now we're close to Wideawake, and in external view, Ascension Island is in view, it will be a night landing on Wideawake International.
At 35km, we're at mach 8 and we're not burning anymore, see i told you there was nothing to worry.

At less than 30 km you can start with controlling the Attitude Hold with the 2.5 increment/decrease instead of the 0.5 one to keep our aiming on target.

At 25 km you're not falling anymore, you're gliding and then now it's simple atmospheric and classic flight, no more need of your MFD you can drop the attitude hold.
Get aligned to the Wideawake airfield and land safely, if you did great you should not even have to use the main engine.
And in the end you should have used only 10% of fuel since ISS


Good luck, this should work for every kind of ships and shuttle.

[Carrion]

Thanks Robsoie.  I will be running through this soon.

[Nistenf]

Thanks for the tutorial!

I just put an Arrow in Orbit by the editor,then sent some UCGO base modules to it with an XR2, then went to the moon and deployed the base, now time to go back home. Anybody knows more base-building UCGO (or not, but preferably) add-ons?

[Robsoie]

I found this on Orbit Hangar , not sure if it allows you to transport bases parts ingame or if it's only some kind of utility to build a base :
http://www.orbithangar.com/searchid.php?ID=3929

Needs 2 addons :
Arianev6 1.2
http://www.orbithangar.com/searchid.php?ID=2872
Inflatable
http://www.orbithangar.com/searchid.php?ID=3909

[sluissa]

I don't suppose anyone's found a pack of base scenery? At the moment, the only bases I have that actually have anything to look at are KSC, the one in Cuba, Brighton Beach, the UMMU demo base, and the one on Mars. All the rest are just marks on the map. and if you try to fly to them they're just a big flat plain. I did download the AIA base, and that's quite impressive, but I'm looking for basically just more runways and maybe a pad or two for the remaining earth bases that have nothing.

[bluephoenix]

I don't suppose anyone's found a pack of base scenery? At the moment, the only bases I have that actually have anything to look at are KSC, the one in Cuba, Brighton Beach, the UMMU demo base, and the one on Mars. All the rest are just marks on the map. and if you try to fly to them they're just a big flat plain. I did download the AIA base, and that's quite impressive, but I'm looking for basically just more runways and maybe a pad or two for the remaining earth bases that have nothing.

Since you already have wideawake international, I will instead suggest the jarvis space centre
EDIT: Also here is the brisbane airport

[Robsoie]

You can get 2 space centers (Kourou in French Guyana and Baikonur in Kazakhstan) from which european and russian space missions are launched too and are nicely detailed in Orbiter :

Baikonur LC1 pad5
(require Soyouz serie )
Baikonur pad24 and Proton UR500

Kourou CSG (French Guyana) - ELA
its extension, Kourou CSG - ELS
Rochambeau airport 50km from Kourou

[bluephoenix]

I really wish I could get lvl 15 textures for the whole earth, that would look nice.