Orbiter-Forum [Challenge] Rescue in Antartica (paper, pencil and a calculator)
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#1
 dgatsoulis Orbinaut
Rescue in Antartica (paper, pencil and a calculator)
by dgatsoulis 11-16-2011, 09:45 PM

I was refreshing my DGIV skills today, going through the mission scenarios folder. Then i remembered that back in the DGIII, there was an extra mission, that appears to no longer be a part of the mission scenarios. I think the name was "Rescue in Antartica" or something similar. The general idea was that a DGIV had crash-landed somewhere in Antartica and you had a limited amount of time to go and save the crew, using only the data from the AE-35 antenna.

So here is the challenge. (Default DGIV settings).

You are in a DGIV sitting on Lpad1 of KSC with a heading of 90 degrees.
You turn on the AE-35 antenna to locate the disabled craft.
The data you receive from the antenna is: Rel. heading 110.495 degrees and distance 11799 km.

1.Find the true heading, true distance and the disabled ship's longitude and lattitude.
2.Calculate the launch azimuth for the suborbital flight.
3.Use the scenario editor to place a DGIV on Lpad1 of KSC (heading 90) and another at the coordinates you found.
4.Take off and land within 50 km of the target and pick up the crew.
5.Take off and land back at KSC.

Help/Hints:
#1 The first part is a trigonometry problem. You can find all the formulas you need and here.
#2 The second part is a bit trickier. You need to know your ship and take the planet's rotation into account.
#3 I'm not posting a scenario, because it will be interesting to see and compare the coordinates and launch azimuth(s) that will be found, by those that try the challenge.
#4 AerobrakeMFD is your friend, but since there is no base to target, you'll have to keep an eye on the Pe/landing position coordinates.
#5 For the fifth part, you'll need to calculate a new launch azimuth for the suborbital flight back to KSC. Fuel will be very limited. (And the launch azimuth might surprise you).

Post your step by step calculations here and if you manage to make the flight, a succesfull playback.

Have fun, happy (sub)orbiting

Last edited by dgatsoulis; 11-16-2011 at 11:13 PM.
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 11-16-2011, 10:29 PM #2 Grover Saturn V Misfire could someone please post a scenario with the two craft placed? although i could probably work out the positions myself, im too lazy, but the flight sounds rather challenging; ive never flown the DGIV suborbital before, and seeing antarctica is a new one for me (lets hope my hover engines dont melt too much ice below me on final approach... else Al Gore will have another inconvenient truth: "you split Antarctica up"
 11-17-2011, 01:32 AM #3 Napalm42 Drell Admiral, Citadel Fleet Wow, I will really be hard pressed on this one. I think I might add a personal challenge thanks to Grover, and limit the amount of time I can use hover/low attitude thrust before the ice begins to suffer severe melting. That'll probably be a 20 m/s descent quickly reduced to 1 or 2 just before touchdown, should be fun.
 11-17-2011, 08:01 AM #4 Spacethingy YSFFTW! Penguins and hydrazine don't mix well, just thought you should know... Sounds fun, I'll give it a go!
 11-17-2011, 08:52 AM #5 Notebook Orbinaut Penguins, just follow the... http://www.orbiter-forum.com/showthr...guin+droppings N.
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 11-17-2011, 11:27 AM #6 RisingFury OBSP developer Quote: Originally Posted by Grover  could someone please post a scenario with the two craft placed? although i could probably work out the positions myself, im too lazy, Quote: Originally Posted by dgatsoulis  #3 I'm not posting a scenario, because it will be interesting to see and compare the coordinates and launch azimuth(s) that will be found, by those that try the challenge. The point is to make your own scenario. The only thing that could be posted would be the starting scenario: DGIV sitting on pad 1 at Cape Canaveral, facing east.
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 11-18-2011, 12:44 AM #7 Tommy Orbinaut Just to save people a bit of time, the coordinates for KSC L-Pad 1 are 28.522764 (Lat) X -80.675896 (Lon). I've had a chance to do the math, but won't have time to try the flight til next week probably. Second DG seems to be somewhere south of Australia - I won't say exactly where my figures show!
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 11-22-2011, 01:32 AM #8 Tommy Orbinaut Had just enough time to set up a scenario and give it a quick try. I had been hoping that I could use the antenna to verify my crash co-ordinates, but no luck there. On the DGIV trying to target the crashed vessel yields an "axis error". I also found that DockMFD can target the crashed DGIV if you use the TGT button - and that told me the distance (no real heading info) of 11.8M, so I'll take that as a clue that my math was OK. None of the other stock MFD's will target a landed vessel, it seems. Just had time for a short "test flight" to try and get familiar with the DGIV again - been a while since I've flown one. The test showed that I need to re-think my ascent, etc, if I'm going to make the round trip without an extra fuel cargo. I used half the fuel, and I'm not sure I had enough energy to get to the crash site. After I had spent more fuel landing I wouldn't have had enough fuel to get back. I'll try the flight again sometime this week, and we'll see what happens.
 11-22-2011, 05:00 AM #9 dgatsoulis Orbinaut Quote: Originally Posted by Tommy  I had been hoping that I could use the antenna to verify my crash co-ordinates, but no luck there. On the DGIV trying to target the crashed vessel yields an "axis error". That's odd, you should get a "pitch limit" msg, but the antenna should return rel. heading and distance values. From your previous post "...south of Australia..." and the verification from DockMFD, i'd say that you have the right coordinates. Quote: Originally Posted by Tommy  Just had time for a short "test flight" to try and get familiar with the DGIV again - been a while since I've flown one. The test showed that I need to re-think my ascent, etc, if I'm going to make the round trip without an extra fuel cargo. I used half the fuel, and I'm not sure I had enough energy to get to the crash site. After I had spent more fuel landing I wouldn't have had enough fuel to get back. With the "PRO904SPECx" ascent autopilot (for both take-offs), my fuel usage was ~57-58% (main) to get to the disabled craft and after cross-feeding from the RCS tank, i landed back at KSC with about 150 kg of total fuel.
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 11-22-2011, 07:38 AM #10 Tommy Orbinaut Quote: Originally Posted by dgatsoulis  That's odd, you should get a "pitch limit" msg, but the antenna should return rel. heading and distance values. From your previous post "...south of Australia..." and the verification from DockMFD, i'd say that you have the right coordinates. Well, one of the delays in flying this is due to problems with my 2010P1 install - I get CTD's when trying to transfer from one vessel to another, etc. It's not a clean install, so I need time to diagnose the problem and find out what I installed that is messing things up. Also, as I said it's been a while since I used the DGIV, so it's possible that it is showing the rel heading and distance - just not where I expect to see it? I was short on time, so I didn't see if there was a FC mode that displayed that - just saw the axis error message and moved on. I'm fairly confident in my math - even though my math-fu is weak. I used a fairly "blunt object" approach that relies on very basic geometry and trig - so it's not elegant but it should get the job done. I also relied heavily on the second page you linked to - especially the section about halfway down that calculated a Great Circle path based on starting location, initial heading , and range. The only part that was even a little bit "tricky" was converting the chord length to the arc length ... (don't want to give up to many hints yet). Quote: Originally Posted by dgatsoulis   With the "PRO904SPECx" ascent autopilot (for both take-offs), my fuel usage was ~57-58% (main) to get to the disabled craft and after cross-feeding from the RCS tank, i landed back at KSC with about 150 kg of total fuel. This is the heart of my current problem. I can get a DGIV into orbit quite a bit more efficiently than the AP - but I need to tailor that ascent profile for a suborbital flight. I haven't done a suborbital in an DGIV, and I've gotten used to the XR series - which uses a different ascent profile and has a much higher glide ratio. I think it's just a matter of getting used to the DGIV again, so I can set up a survivable skip to get me to the target. It seems that the DGIV is a bit less forgiving on 2010 than it was on 2006 - when most other vessels seem to be more forgiving on 2010. I just need to find enough Orbiter time to adjust - rather than having Real Life force me to be in a hurry and trying to force the issue. Hopefully sometime this week - but no promises what with all the Thanksgiving obligations this week. At any rate - it's nice to have a challenge that isn't easily solvable simply by my IMFD skills alone. Even though I use IMFD to help account for planetary rotation!
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 12-05-2011, 12:38 AM #11 dgatsoulis Orbinaut I 'll go ahead and place another "hint" here, that may or may not be so obvious. Everything on Earth's surface, moves from West to East, at a rate of 360 degrees/day ~ 0.25 degrees/minute. You are trying to hit a moving target. If you know how much time it will take you, to get to your destination, then you know by how much you have to aim ahead of it.
 12-05-2011, 02:30 AM #12 Tommy Orbinaut Well, I've completed the flight. Or should I say flights - the recorder doesn't handle UMMU transfers, so I made two recordings. Even the gear status isn't recorded - the viewer will have to press the "g" key at the appropriate times during playback to raise and lower the gear. BTW, how did you get the ascent autopilot to accept a heading with over 2 digits? Anyway, I'll put together a little PDF with my math and explanations, then pack it with the flight recordings, and post it in a couple days.
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 12-05-2011, 02:44 AM #13 dgatsoulis Orbinaut Quote: Originally Posted by Tommy  BTW, how did you get the ascent autopilot to accept a heading with over 2 digits? Easy, i launched at the correct heading, and then i waited untill the speed was over 500 m/s. Then I used the autopilot. Quote: Originally Posted by Tommy  Anyway, I'll put together a little PDF with my math and explanations, then pack it with the flight recordings, and post it in a couple days. Looking forward to seeing that! I've done something similar, myself! It will be nice to compare notes. Last edited by dgatsoulis; 12-05-2011 at 02:47 AM.
 12-05-2011, 03:55 AM #14 Napalm42 Drell Admiral, Citadel Fleet For all of my experience, I can't for the life of me hit that target. I'll just wait until some instructions come out. I can do any sort of interplanetary mission, but when you tell me suborbital, don't expect a fing.
 12-06-2011, 12:20 AM #15 Tommy Orbinaut Quote: Originally Posted by dgatsoulis  Easy, i launched at the correct heading, and then i waited untill the speed was over 500 m/s. Then I used the autopilot. I see. I used a very different profile - but since I'm quite out of practice with the DG-IV I sort of "missed" the optimum and figure I wasted about 4 -5 kg of fuel on the first ascent. Second was a bit better - but still not great. It would be interesting to know how long it took you to complete this, I took 1:45, with 7 minutes on the ground at the crash site. With a bit of practice I could easily shorten that up with more aggressive braking. Quote: Originally Posted by Napalm42  For all of my experience, I can't for the life of me hit that target. I'll just wait until some instructions come out. I can do any sort of interplanetary mission, but when you tell me suborbital, don't expect a fing. There will be a couple of "tricks" in my pdf, ways of using MFD's in ways they weren't really designed for, that will help you with that. The first flight is still pretty tricky.

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