Challenge Earth to Saturn in XR-2

[Cairan]

Greetings,

It's been a while since the last time I took time to make a long trip, but yesterday I took off from the XR2 scenario ready to dock to the ISS, which I did after about 2 hours in flight time. Once there, I figured I could go to the moon, and landed at the Niven base, from an add-on...

But then, it occurred to me that Mars was in a proper position for the XR2 to reach it, so I loaded up one LOX pallet and an additional XR2 fuel tank in the cargo bay and took off for Mars... I used aerocapture by aiming for 27.5 km altitude, and after skipping off once after capture, using Aerobrake MFD, I landed at Olympus just as the sun rose over the horizon...

But heck, why stop there, I figured that both Jupiter and Saturn were in proper positions for a trip there... I chose to go to Titan, as I have set up a base there... Total required delta-V was about 15 km/s ... So I sent an XR-2 with only 5 people aboard and 2 full LOX tanks in the cargo bay and sent another XR-2 with only the pilot and copilot and a cargo bay full of fuel to rendez-vous with it... Docked the two ships nose-to-nose, and used the fueled XR-2 to provide a booster stage to leave Mars, undocking just prior to reaching escape velocity. I switched to the Titan-bound XR-2 and finished the burn to place myself on a 2000+ days trajectory for the Saturn system. While the ship was in transit, I aerobraked the Booster XR-2 for a safe landing at Olympus about 3 weeks after departure from Mars.

I arrived at Saturn in 2007, with about 120 days of O2 left and 50% of fuel... Once in the region of influence, I adjusted my trajectory to intercept Titan with a minimum of inbound delta-V, about 4.5 km/s, which required a burn of about 15-20 seconds. I aimed for an aerocapture at 120 km of altitude, and still using Surface MFD and Aerobrake MFD, I managed to be captured by Titan at about 4.5 G peak, 3.5 average and braking at around 130 km of altitude with an AOA of 10-15 degrees, a bank of 95 and a relatively cool reentry at 800 Celcius, being careful not to overload the wings.

Before I lost too much energy, I skipped back up to about 1400 km of "apogee" and using a small burn midway to this altitude, I corrected for a re-entry right over my base, Huygens, located near the position of the Cassini probe landing site... At 600 km altitude, I deployed the aerobrake, followed at 200 km with the retro and hover doors. The radiator was deployed all along ever since I skipped back out on aerocapture. For the whole aerocapture and final approach, I did a series of S-turns to keep aligned with the base. I descended with a 45 degree glide path, with a terminal velocity of about 35 m/s... At 1000 meters, I lowered the gear and pull-up to null-out my vertical speed, and at 600 meters I activated the autoland hover autopilot, using retro to kill my residual forward momentum.

Wheel stop was at about 2500 days, from Kennedy Space Center to Saturn's Titan. Can you do it faster, or with more passengers, still in an XR2?

 

[dgatsoulis]

Wheel stop was at about 2500 days, from Kennedy Space Center to Saturn's Titan. Can you do it faster, or with more passengers, still in an XR2?

Hi Cairan,

It's been a while since i took a long trip in a Ravenstar, but this challenge seems interesting.

Let me see if i got it right.

Cape => ISS => Land on Olympus base on Mars => land on Titan.

All of the above in less than 2500 days.

Do you want to use expert settings for the XR2 or the default ones?

 

[Cairan]

Hi Cairan,

It's been a while since i took a long trip in a Ravenstar, but this challenge seems interesting.

Let me see if i got it right.

Cape => ISS => Land on Olympus base on Mars => land on Titan.

All of the above in less than 2500 days.

Do you want to use expert settings for the XR2 or the default ones?

Actually, it was:

Cape -> ISS -> Moon base -> Mars base -> Titan base

I think I was on the default settings for the ISP, SCRAM was at 0 (reallistic), LOX was set at 364 kg and consumption at 4 (100%).

 

[markl316]

Greetings,

Once in the region of influence, I adjusted my trajectory to intercept Titan with a minimum of inbound delta-V, about 4.5 km/s, which required a burn of about 15-20 seconds.

So what exactly did you mean by this? Did you go directly to Titan without orbiting Saturn? If so, were you using transx or IMFD?

 

[Cairan]

So what exactly did you mean by this? Did you go directly to Titan without orbiting Saturn? If so, were you using transx or IMFD?

Exactly, I landed on Titan with an XR2 without getting captured by Saturn first... I used Titan to be captured by the Saturn system...

You have to hit Titan when it is on the sunward side of Saturn (ie. Sun-Titan-Saturn alignment) as this provides the least velocity differential between your ship and the atmosphere of Titan, as it revolves around Saturn at a certain orbital velocity.

The act is quite delicate to balance as the dense atmosphere of Titan makes for a very stressful experience on the wings (wing loading), but then the low gravity of Titan requires that you provide lift toward the moon to keep from getting ejected while you use the atmosphere to slow down. Oh and I was using IMFD all the way.

 

[Mogeley]

So this challenge is without the warp drive addon right? Just kidding here...

Can we skip certain steps like the ISS or the moon (if it's possible)? or does it have to be the same progression?

 

[flytandem]

Thanks for the fun challenge. I took the liberty to modify to make my own challenge. I have no idea how to get an xr2 in my copy of orbiter and probably couldn't figure out systems like the O2 etc. But a challenge to fly the task, without refueling, in a DG came to mind. What's the total devtaV of the XR2 BTW? Maybe it could be done without refueling?

Anyway I started by placing a surrogate on Mars to see when a good window to go from there to Saturn (Titan) was. I guestimated what fuel might be left and estimated an eject strength. Nothing calculated just guessing based on previous trips to Mars and what might be left for the last leg.

Then I used the ship on earth to find a window to Mars to arrive on the date of the start of the Mars Saturn leg. I noted the direction of the eject from Earth (and location of the pe at Earth) and used that to know where the moon should be. The plan would be to drop from the moon to the earth for a gravity well burn.

Then I started sitting on earth 1 month before the eject and noted when the 2 window to go offplane from ISS to moon were. I also noticed that the moon would be in place for the gravity well drop about 10 days late. No worries, I just re-planned the Earth Mars trip for the later start date and tweaked to get the same (correct) arrival date. I advanced the date of the sim to 3 hours before the time to go from ISS to moon and I was off. Date 58330.2

I got to ISS in 1 orbit and then 1 orbit later did the eject for offplane hohmann transfer to the moon. Landing was typical and done randomly somewhat equatorial. Why land at a base if I am not getting any fuel?

That had me waiting on the moon for about 6 days from 58334 to 58340. That had the moon at the right point to start a drop back to earth for a close pass and gravity well burn at 58344. A surrogate orbiting earth acted as a target to help me drop to Earth in the correct alignment for the earth/Mars trip.

Arrival at Mars was at 58776, right on schedule. There was just a few minutes there before taking off for the trip to saturn. Why waste time?

It was a close guess on the fuel and actually too close. The main tank was going to run out doing the eject burn but the RCS was still almost untouched. So I used editor to transfer exactly 500 Kg of fuel from RCS to main. Cheating? Maybe. It still only transferred fuel within the ship and didn't add any from external supply. I think other ships are able to do this within the cockpit.

Arrival at Titan was soft on 60287 pulling 1.5 g's inverted on initial contact with the atmosphere. There was only 700 m/s of deltav left total in the ship. Nice dead stick at the base I have on Titan.

Total flight time from earth to titan was 1957 days.

 

[markl316]

Exactly, I landed on Titan with an XR2 without getting captured by Saturn first... I used Titan to be captured by the Saturn system...

Oh and I was using IMFD all the way.

Wow...do you think you could make an annotated playback (or just step by step instructions) of how to do that? I've always wanted to know...and it would be a great addition to my IMFD manual, with credit to you, of course :thumbup:

---------- Post added at 02:06 AM ---------- Previous post was at 01:12 AM ----------

Never mind, figured it out...that was really cool!!

 

[flytandem]

Help?
Out of curiosity I tried to get an XR2 into my orbiter. Downloaded the UMMU as suggested. I already have orbitersound. Then the 89.1 meg zip file for XR2 Ravenstar.
They seemed to install correctly but Orbiter ctd's on starting any of the Ravenstar scenarios. Any other non-ravenstar scenarios still start fine.
What are those 36 parts of rar files on the download page??
anyway, Here's the orbiterlog after a ravenstar ctd at startup...

**** Orbiter.log
Build Sep 29 2006 [v.060929]
Devices enumerated: 4
Devices accepted: 3
==> RGB Emulation
==> Direct3D HAL
==> Direct3D HAL (Mobile Intel(R) 4 Series Express Chipset Family)
Found 0 joystick(s)
Module AtlantisConfig.dll [API v.060425]
Module DGConfig.dll [API v.060425]
Module AbsoluteKillrot.dll [API v.060425]
Module ScnEditor.dll [API v.060425]
Module BurnTimeMFD.dll [API v.060425]
Module BaseSyncMFD.dll [API v.060425]
Module InterMFD.dll [API v.060425]
Module CustomMFD.dll [API v.060425]
Module ExtMFD.dll [API v.060425]
Module OrbiterSound.dll [API v.060425]
Module VistaBoost.dll [API v.060425]
VistaBoost 1.0: Warning: font smoothing already disabled; nothing to do.
Module transx-3-13-1-3.dll [API v.060425]

**** Creating simulation session
DirectDraw interface OK
Direct3D interface OK
Zbuffer: 32 bit
Render device: Fullscreen 1280 x 800
Device has no hardware T&L capability
Module Sun.dll [API v.050206]
VSOP87(E) Sun: Precision 1e-006, Terms 554/6634
Module Mercury.dll [API v.050206]
VSOP87(B) Mercury: Precision 1e-005, Terms 167/7123
Module Venus.dll [API v.050206]
VSOP87(B) Venus: Precision 1e-005, Terms 79/1710
Module Earth.dll [API v.050206]
VSOP87(B) Earth: Precision 1e-008, Terms 2564/2564
Module Moon.dll [API v.041022]
ELP82: Precision 1e-005, Terms 116/829
Module Mars.dll [API v.060425]
VSOP87(B) Mars: Precision 1e-005, Terms 405/6400
Module Phobos.dll [API v.060425]
Module Deimos.dll [API v.060425]
Module Galsat.dll [API v.041022]
Module Jupiter.dll [API v.050206]
VSOP87(B) Jupiter: Precision 1e-006, Terms 1624/3625
Module Io.dll [API v.041022]
Module Europa.dll [API v.041022]
Module Ganymede.dll [API v.041022]
Module Callisto.dll [API v.041022]
Module Satsat.dll [API v.061227]
Module Saturn.dll [API v.061227]
VSOP87(B) Saturn: Precision 1e-006, Terms 2904/6365
Module Mimas.dll [API v.050206]
SATSAT Mimas: Terms 113
Module Enceladus.dll [API v.050206]
SATSAT Enceladus: Terms 33
Module Tethys.dll [API v.050206]
SATSAT Tethys: Terms 101
Module Dione.dll [API v.050206]
SATSAT Dione: Terms 59
Module Rhea.dll [API v.050206]
SATSAT Rhea: Terms 68
Module Titan.dll [API v.050206]
SATSAT Titan: Terms 100
Module Hyperion.dll [API v.050206]
SATSAT Hyperion: Terms 595
Module Iapetus.dll [API v.050206]
SATSAT Iapetus: Terms 605
Module Uranus.dll [API v.050206]
VSOP87(B) Uranus: Precision 1e-006, Terms 1827/5269
Module Miranda.dll [API v.060425]
Module Ariel.dll [API v.060425]
Module Umbriel.dll [API v.060425]
Module Titania.dll [API v.060425]
Module Oberon.dll [API v.060425]
Module Neptune.dll [API v.050206]
VSOP87(B) Neptune: Precision 1e-006, Terms 391/2024
Module Triton.dll [API v.060425]
Finished initialising world

 

[dbeachy1]

I noticed this in your Orbiter.log:

Devices accepted: 3
==> RGB Emulation
==> Direct3D HAL
==> Direct3D HAL (Mobile Intel(R) 4 Series Express Chipset Family)
...
Device has no hardware T&L capability

Unfortunately you're probably out of luck -- the XR2 has lots of high-res textures, and I've seen Orbiter often crash in video modes without T&L capability.

 

[flytandem]

Thanks Doug,
BTW, one reason other than overall curiosity was to see what the deltaV of a fully loaded XR2 is. I wanted to compare it with the stock deltaglider that has about 31,500 m/s with 4 people on board.
rob

---------- Post added at 03:25 PM ---------- Previous post was at 02:29 PM ----------

I have an Acer 64 bit w'vista desktop. So I transferred my orbiter folder with the ravenstar installation over to this computer. It has the T&L and I tried all video options with no luck getting a ravenstar scenario to load. The stock scenarios load fine.
Here's the log after the ctd on startup.

**** Orbiter.log
Build Sep 29 2006 [v.060929]
Devices enumerated: 6
Devices accepted: 5
==> RGB Emulation
==> Direct3D HAL
==> Direct3D T&L HAL
==> Direct3D HAL (NVIDIA GeForce G100)
==> Direct3D T&L HAL (NVIDIA GeForce G100)
Found 0 joystick(s)
Module AtlantisConfig.dll [API v.060425]
Module DGConfig.dll [API v.060425]
Module AbsoluteKillrot.dll [API v.060425]
Module ScnEditor.dll [API v.060425]
Module BurnTimeMFD.dll [API v.060425]
Module BaseSyncMFD.dll [API v.060425]
Module InterMFD.dll [API v.060425]
Module CustomMFD.dll [API v.060425]
Module ExtMFD.dll [API v.060425]
Module OrbiterSound.dll [API v.060425]
Module VistaBoost.dll [API v.060425]
VistaBoost 1.0: Warning: font smoothing already disabled; nothing to do.
Module transx-3-13-1-3.dll [API v.060425]

 

[dbeachy1]

As a test, I recommend starting with a clean installation:

1. Install Orbiter 060929 to a new folder (e.g., C:\OrbiterClean).
2. Run it and select a video mode with T&L capability. Verify that a default DG scenario loads successfully.
3. Install OrbiterSound and retest a default DG scenario.
4. Install UMMu and retest a default DG scenario.
5. Now install the XR2 to your clean Orbiter folder (e.g., C:\OrbiterClean) and load one of the default XR2 scenarios.

If that doesn't work then something odd is going on...

 

[n72.75]

2500 days

I love the XR-2 but spending 7 years in it sounds like hell.

 

[dbeachy1]

I love the XR-2 but spending 7 years in it sounds like hell.

Don't worry, for a mere $96,800,000 per crew member Altea Aerospace will be happy to upgrade your XR2 with our state-of-the-art cryogenic pods. "Don't leave Earth without it!" :tiphat:

 

[Sky Captain]

I love the XR-2 but spending 7 years in it sounds like hell.

When I do a long trip with XR2 or DGIV I usually name the crew after my most hated politicians then long travel time stops being an issue:lol:.

 

[flytandem]

Thanks Doug. The clean install did the trick. Nice.

Lots to do getting into orbit with the ravenstar. I died a half dozen times before eventually making it. By the 10th try I managed to do it fairly well using nearly all of the scram fuel to minimize usage of the main tank.

To answer my previous question, the deltaV of the Ravenstar, after reaching low Earth orbit, is about 8500 m/s. YMMV. This is plenty to go pretty much anywhere in the solar system directly. I think going to Neptune directly might be close though.

There's no way one could do the challenge of this thread without refueling. I think they could go to the ISS, then moon landing without refueling at ISS, and would probably be about 250 m/s short for the trip to Mars without refueling at the moon.

By comparison, a stock DG has about 2200 m/s deltaV after reaching LEO. Easy to go lots of places without refueling.

Nice work Doug. I can see why many Orbitnauts like the XR2.

 

[dbeachy1]

Thanks. :tiphat: Anyway, if you want to install the rest of your add-ons alongside the XR2 the first step will be to pin down which add-on was causing the CTDs. Here's how to pin it down:

1. Back up your still-working working installation (e.g., C:\OrbiterClean).
2. Install one of your favorite add-ons and re-test an XR2 scenario.
3. If you get a CTD, then you've found the (or a) problem add-on; at that point you can revert to your saved installation from step 1 to uninstall the problem add-on.
4. Return to step 1. Repeat until all your favorite add-ons have been tested/reinstalled.

Then once you have a list of add-ons that CTD'd, you can contact the add-on author(s) via PM and see if there's a fix.

EDIT:
One more thing about delta-V: you can change the ISP, etc. for an XR vessel by editing its configuration file; e.g., C:\Orbiter\Config\XR2RavenstarPrefs.cfg.

 

[flytandem]

Thanks. Actually I did that last night immediately after the install was working. I added the killrot, latest transx, reentry, and burntime and still was fine.

I don't know why the previous try on the laptop failed but i did notice that when unzipping the xr2 file, it was unzipping very slowly. Usually it would do operations like that in a few seconds, but it churned away unzipping for 5 minutes showing the names of the files it was slowly progressing. Strange.

I'm always amazed at the fine work done by those doing addons for Orbiter.

 

[Cairan]

Never mind, figured it out...that was really cool!!

As Titan revolves around Saturn, and Saturn around the Sun, Titan (and every natural and artificial satellites) actually are orbiting the Sun in a zig-zagging path around their parent body...

By intercepting Titan as it is on the sun-ward side of it's orbit around Saturn, it's Sun-relative velocity is at it's lowest, and therefore also relative to the incoming space ship... it substracts Titan's orbital velocity from Saturn's orbital velocity when Titan is perfectly aligned with the Sun and Saturn, but adds up when Titan is in opposition with the Sun, relative to Saturn. And that turns out to be a huge difference in delta-V! (more than double)

The idea is to wait to be in Saturn's gravity field (>0.50 influence) so that we can switch IMFD to Saturn as the reference body and Titan for the target... The interception date is then played with Adj-100x set, so that the incoming velocity is the smallest arriving at Titan...

Then, arriving at Titan, you switch to Base approach to set an Orbit insert at 120 km, and using Aerobrake MFD (or other favorite flavour), you adjust your trajectory to skim the atmosphere deep enough to have sufficient lift to counteract the centripetal force, by using your lift to "dive" and "grip" into Titan's atmosphere, the opposite of what we are used to in normal flight: using lift to keep from falling toward the gravity source.

By careful management of angle of attack and bank angle, you can manage to do a series of roll reversals while being inverted to keep on target for the intended landing site, while being not too much agressive on the AOA as it severely stresses the wings...

In my Titanian aerocapture, the three gauges I watched the most were my vertical speed on Surface MFD, the Wing load indicator and the accelerometers to limit G-forces to less than 4.5 G. Once the proper altitude (between 125 km and 130 km) is reached and the ship stabilized so that the vertical velocity is always either slightly negative or null, the hull temperature is not a factor and remains at a very safe 800 Celcius.

Beware that Titan's atmosphere is so dense and the gravity so low that if you underbank for even a few seconds, you can start skipping out of the atmosphere, and if you overbank or overpitch, the loading on the wing will overstress them.

Once you get to about 1500 m/s, you can peak at Orbit MFD or Aerobrake MFD to verify that you are indeed captured by Titan, and Saturn in the same stroke, and adjust your trajectory to reach your intended landing site... In my case, I let go of the re-entry attitude when my apoapsis was down to over 1000 km, and coasted back out of the atmosphere to set up my final reentry over my base...

Voila! Bon voyage!

 

[markl316]

As Titan revolves around Saturn, and Saturn around the Sun, Titan (and every natural and artificial satellites) actually are orbiting the Sun in a zig-zagging path around their parent body...

Brings back memories of high school calculus...our teacher gave us that problem. He said "the moon revolves around the earth, and the earth revolves around the sun. The earth's period is 365 days, and the moon's period is 27 days. Find the parametric equations for the moon's path around the sun. You have one week." :lol: