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Oceanic Oceanic is offline
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Videos DG-IV Reentry Video Tutorial
by Oceanic 05-25-2009, 04:42 PM

There's a lack of reentry tutorials, especially for beginners, i want to share my experience how to bring the DG-IV back home.

You should:

* - read ar81's Concepts for atmospheric reentry tutorial first, it can be found
here
. It will help you understand what it takes to bring you bird back down.

* - be familiar with the DG-IV (how to use the flight computer and the basic controls)


You will need:

AerobreakMFD

BasesyncMFD
Wideawake International

DeltaGliderIV


Update: made a video, hosted on vimeo.com, unfortunately the aspect ratio is now off which makes the MFDs hard to read. i will look in to it. if you are registered on vimeo you can download the original video which is 140mb big but has the right aspect ratio.





Let's Start:

Load the Scenario "DeltaGliderIV/Earth Scenary/Docked to Mir"

- undock from Mir, close your Nose Cone, turn HYD Pressure off.
- open Map MFD select Wideawake International as target.
- open COM/NAV MFD set Nav1 to 113.30 (Runway 12 at Wideawake, the long one in the center) set Nav2 to 113.00 (Wideawake Navbeacon)
- open BasesyncMFD on the right. click on TGT, type in Wideawake International hit enter. click on E/D this will switch BasesyncMFD between equatorial and direct mode, we need direct.
- open AerobrakeMFD on the left, click on TGT, type Wideawake International hit enter. click on PG (this will set AerobrakeMFD to the Graph/Map mode) click on PRJ so we see the Map display


your MFDs should look like this:





- start Orbit (-) Normal autopilot when you reach the ascending node and burn until our 4th orbit pases within 2km over Wideawake International


Basesync Should look like this:





- speed up time until you reach the opposite side of the planet on our last orbit, start the retrograde autopilot. hit D2 on your keyboard to activate the DG-IV's "Deorbiting Display". you will see on the AerobreakMFD your flight path directly over Wideawake International.


Start your burn:





- burn till Pea reads 60km and Reentry Angle Prediction about 0.7 on the D2 display





- AerobreakMFD shows that we are a tiny bit off, but thats ok for now. type D65 (reentry check). close your hover and retro doors, select surface MFD on the right, change HUD to surface. pump rcs fuel to the main tank, leave about 110kg in the rcs tank (if we have to start our main engines to reach our base, it is better to have the fuel in the main tank, the reentry autopilot will use 5-10 kg rcs fuel, if we leave ~110kg we won't be nagged by the low fuel alarm).

- speed time up until you alt reads 160km. engage the manual reentry autopilot to an AOA of 40 (p104s40 on the keyboard)


you will see that my flight path is not directly over Wideawake International





- adjust your bank so that our flight path is directly over Wideawake International (only works in 5 steps with the p104s40 autopilot but thats enough, 10 did it for me)





- you can speed time up till the autopilot disengages the timewarp automatically at about 90km altitude, switch your DG-IV flight computer display to "Reentry Control Display" (D3 on your keyboard)

- you see that i will over shoot Wideawake, i pull up to 60 AOA for a few seconds so that i adjust my reentry over the base (depends on your altitude how long it will take, its better to do this while you are still over 70km alt, if you are to short pull down to 30 AOA)





take a drink and watch your descent

- if you you try for a unpowered landing, you will need too keep an eye on the target distance (this can be found on our AerobreakMFD, the value is " " Dist:") and hold it at 2km. to do this you will have to adjust your AOA constantly. it is important that you hold more or less that 40 AOA only for a very short period of time. you will use more rcs fuel doing this, transfer 10kg back in the rcs tank to be on the save side. we don't want to be distracted from the low fuel alarm.

- at 47km altitude our hull temperature reads 1605 C it won't go much higher if you did it right.

- at 25km alt switch the ship control to "elevon & gear", and switch the HYD gear pressure on. select HSI MFD on the left, (we don't need AerobreakMFD anymore) disengage the reentry autopilot! watch your G-force and your hull temperature while you turn and align with the Runway. fire up your main engines if you are to far from the base. it is better to be a bit too fast than to come in to short. if you try to land without firring you main engines again try to hold 8 km altitude when you reach a distance of 5km from the runway, pitch down aim for the runway safety area. start pulling up at 2km alt. don't get too fast use your speedbrake if you are going over 300m/s (the D3 display shows the status of the speedbrake) when you reach 500m drop very slowly you altitude.
open your gear and try bringing the glider down as gently as possible. don't forget the Runway is almost 5km long and the DG-IV has good brakes, you have time to land.


had some trouble aligning with the runway and going too fast





this led to the destruction of the landing gear






last words:


- don't exceed 19t kg ship weight (the reentry autopilots wont start if you are too heavy)
- remember to switch the HYD Pressure back on before you attempt to land
- a complete unpowered landing is unforgiving (is way easier with the XR-1, the aerodynamics of the DG-IV are not the best for beginners)
- don't forget to switch the ship control to "elevon & gear". at least 3 times the "atm auto" switched to rcs on the last few meters and killed my crew or disabled my ship.
- save between the burns, and especially before your landing (it's quite annoying losing the ship on the last few hundred meters)
- if you can get the DG-IV back home it will be easy with the XR - family


hope this helps you bring the DG-IV back home.


reentry and a complete unpowered landing, is the most challenging and most fun thing i came across in orbiter, don't feel bad if you don't succeed at your first attempt.

Last edited by orb; 01-07-2012 at 05:51 AM.
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Old 05-25-2009, 04:50 PM   #2
Kaito
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Wow, excellent tutorial!
Its nice that someone took the time to do this. It was needed. Badly.
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Old 05-25-2009, 06:23 PM   #3
Tex
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Very nice mate! I will check this out later when I have time to sit down and read it and give it a try!

BTW: Feel free to add yourself to the Tutorial Publishers group from the User CP. Look for the 'Group Memberships' link on the left side of that page.
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Old 05-25-2009, 11:42 PM   #4
kevinvr
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Thanks for that Oceanic,
I will try it on the weekend!
Looks great!
all the best,
Kevin
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Old 05-26-2009, 12:45 PM   #5
Oceanic
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thank you all

let me know if it helped

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Old 05-27-2009, 09:00 PM   #6
kevinvr
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Hi Oceanic,
I started doing this and when I gor to "- start Orbit (-) Normal autopilot when you reach the ascending node and burn until our 4th orbit pases within 2km over Wideawake International" below the first picture - i got stumped.

Here are my questions:
1. What is the ascending node and where do I find it.
2. Is 4th orbit on thebasesyncMFd - the 4th line?

I have used align planes MFD and saw Ascending Node and Decscending node there , but I dont see it here.
Please excuse my lack of understanding and thank you for your pacience.
all the best
Kevin

Last edited by kevinvr; 05-29-2009 at 12:49 AM. Reason: I forgot to make this a question.
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Old 05-29-2009, 01:00 AM   #7
Tommy
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I can answer that for you. The 4th orbit is the 4th line, but you can wait a couple orbits if you desire. I myself only get my closest approach within 50k until after I de-orbit. If you've pressed the E/D button and are in direct mode, the nodes will be at right angles to the base location on the circular map on BaseSync. You can check the Time to Node (TN i think it's called) to see which way to burn. BaseSync won't give a countdown until the last couple minutes before the final node, so the number will be counting up from the last node. This means you need to reverse the thrust direction indicated by the PLC value. If PLC is positive, your next burn will be anti-normal, and if PLC is negative you'll be burning normal. It's good enough to "eyeball" the burn timing by watching the graphics on BaseSync.

I usually do a "rough" alignment at the first node on my final orbit, then de-orbit sometime after I'm opposite the base, but at least 16.5M from the base. Then I'll use BaseSync to fine tune the approach at the final node, and rarely need to bank until beginning initial runway alignment.
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Old 05-29-2009, 01:42 AM   #8
kevinvr
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Thanks Tommy,
I will print that and try again,
appreciate the help!
Have a great weekend!
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Old 05-31-2009, 04:23 PM   #9
wehaveaproblem
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muhahaha excellent stuff Oceanic, you are drawing more hapless fools to their deaths in the south Atlantic! Adding their broken vessels to the manmade reef of wrecked ships in the sea around Ascension! lovely jubbly!

hehe just joking, nice tutorial, I'm honored you chose Wideawake as the objective.
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Old 06-03-2009, 11:17 PM   #10
Oceanic
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sorry i didn't answer in a long time
was kinda busy

i made a tutorial video that will hopefully help even more. be gentle with me it is the first video i ever made. i tried it to keep it pretty simple. comments and critic are welcome. i will ad the link as soon as vimeo is done converting it.

@wehaveaproblem

theres no better place to bring back my birds than Wideawake. i'm sure the Spacetech Company and Altea Aerospace disagree with me on that one, regarding the dozens gliders i managed to put to rest on the bottom of the ocean :D
your addon is just fantastic, comes directly after OrbiterSound and the DGIV on my personal favorite addon list.

---------- Post added at 01:17 AM ---------- Previous post was at 12:27 AM ----------

video is up
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Old 06-04-2009, 09:36 AM   #11
kevinvr
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""the dozens gliders i managed to put to rest on the bottom of the ocean"

He he , I know what you mean.
Looking forward to that video. I've been using your tutorial and had about 3 successful re-entries, but always end up too far from base and crash into the sea

Keep on keeping on
have a great week!
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Old 06-04-2009, 01:53 PM   #12
Oceanic
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Quote:
Originally Posted by kevinvr View Post
 ""the dozens gliders i managed to put to rest on the bottom of the ocean"

He he , I know what you mean.
Looking forward to that video. I've been using your tutorial and had about 3 successful re-entries, but always end up too far from base and crash into the sea

Keep on keeping on
have a great week!
yeah it's just a huge cemetery down there
let me know if the video helped
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Old 06-04-2009, 02:01 PM   #13
MJR
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I'm glad I got the reentry part down awhile ago. I learned from trial and error. As well as other things. Anyway you have a great tutorial.
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Old 06-04-2009, 06:01 PM   #14
ar81
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Quote:
Originally Posted by kevinvr View Post
 Here are my questions:
1. What is the ascending node and where do I find it.
Node is where two orbit planes meet.
Ascending node is the node where you cross the other orbit while heading somewhat to the north in MapMFD.
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Old 06-04-2009, 06:26 PM   #15
MJR
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You can also find it in the Align planes MFD.
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