Dreams of Duna (image heavy)

[meyst]

This thread is going to log my progress and attempt at the Duna Permanent Outpost Mission Architecture Challenge

I have been working on a new lifter for the project that I have named the Sylph. The lifter has a total loaded mass of 64.95 tons (payload [the stack of batteries with a nose cone], 4 tons + upper stage, 12.25 tons + lower stage, 48.7 tons) Allowing the vehicle to count for a re usability bonus by recovering the lower stage. Payload fraction 6.16%

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VAB description. The craft can put a 4 ton payload into a 100x100 parking orbit.

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Lower stage recovery test, just after stage separation. The stage retains 4 tons of fuel for landing

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As the gravity turn has it moving away from the space center a horizontal burn is used to set up a return for landing.

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After the burn the stage free falls back to the space center

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On final approach. A thrust to weight of over six to one allows the vertical speed to be arrested rapidly in the last few hundred meters.

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Landed on a field in view of the space center

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The Sylph does have a rare, perhaps special, capability. Engine out capability.

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Denied the thrust of one of it's LVT 30's and carrying a full payload the Sylph claws skyward. The ships 6 reaction wheel systems provide the massive control authority needed to keep the ship upright while fighting brutal asymmetric thrust and allowed a maneuver to avoiding a ground hazard (flag pole).

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This early in the flight the loss of an engine causes huge gravity losses to the ships Delta V. So a choice needs to be made either continue on as normal, recover the lower stage and accept the risk that a second engine failure on the upper stage would result in the loss of the payload or burn the landing fuel reserve on ascent to maintain engine out capability on the upper stage. For this test I opted to burn the landing reserves to retain upper stage engine out capability but value of the lifter vs risk to the cargo would need to be determined on a case by case basis.

A third option also exists, abort the launch by landing the rocket. This would be accomplished by hovering on the three engines until the total fuel loading in the lower stage drops below 10 tons, at that point the engine opposite the failed engine can be shut down to balance the thrust and enable a safe low thrust to weight ratio landing.

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After fighting with the controls for a minute I find a 'sweet spot' that allows the SAS system to hold the ships course as it picks up velocity.

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Stage separation. An upper stage engine fails to light!

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The upper stage struggles on with a disabled engine as the lower stage returns to Kerbin for some hardware assisted lithobraking.

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The crippled Sylph limps into a very low but stable orbit with an Apoapsis of 80,281M and Periapsis of 71,351M. Proving the rockets capability of losing an engine on both stages, at the worst possible time, without a loss of payload. In my opinion that counts as a 'robust design'.

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[zekes]

wow very reliable! I wish i had engine out on my T-9.... course you aren't flying a 900 ton ship....

[Death Engineering]

Built in backup plans and powered descent recovery! Very cool!

[Rhyunix]

A very nice reusable and efficient design. Like it!

[DMagic]

Wow, very nice design. Can you actually land the first stage and put the upper stage into orbit at the same time? I can imagine the upper stage drifting to its apoapsis while you handle the landing; it would be awesome if there were enough time for that.

[meyst]

Thank you for the kind comments!

Can you actually land the first stage and put the upper stage into orbit at the same time? I can imagine the upper stage drifting to its apoapsis while you handle the landing; it would be awesome if there were enough time for that

No, this lifter can't do that. I like to think the lower stage lands using automation while I am running the ship up to orbit. I think if one built a rocket that took a core stage up to apoapsis and used an upper stage to quickly circularize the orbit it would be possible to go back to controlling the detached core in time to land it.

The specific challenge I built this lifter for requires that craft that generate heating flames be equipped with heat shielding parts, so I made the lower stage separate earlier to avoid the need to install heat shielding parts on it.

[meyst]

I have created a crew transfer vehicle that takes advantage of the safe Sylph lifter.

I present the Sylph Tarriance spacecraft.

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Gilrick looks to be having second thoughts about volunteering to 'test the newest rocket' after discovering what 7.5 Gee's feels like. Our brave Kerbal was fired 370 meters away in 3 seconds. The escape tower is then jettisoned and the spacecrafts maneuver drives light to take our Kerbal well away from any flaming debris before dumping the remaining section and landing a safe distance away.

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Gilrick leaves the capsule after eating the emergency snacks. He said the escape system works.

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[meyst]

The space center is a hive of activity as a plethora of experimental craft vie to be a part of the upcoming Duna mission.

One such exotic craft being considered is this Duna mobile Habitat. Able to enter Duna under propulsion to avoid entry heating, fly in atmosphere, refuel while grounded or in orbit and with enough delta V on a full fuel load to comfortably make Duna orbit. Also designed, but untested, for engine out capability in the weaker Duna gravity.

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Jeb landed it on the VAB after flying around the space center.

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Down sides that are likely to keep it from the plan are the 3 launches to put it into orbit, additional infrastructure to build it in orbit of Duna and service it while grounded. It is also thirsty! Requiring additional launches to fuel it at Duna (would go up to space and transit in pieces empty), I figure about 16 launches would be required to reasonably build and operate it at Duna. Still I thought it epic enough to be worth sharing.

Edited August 3, 2013 by meyst

[meyst]

I have been working on a small unmanned craft that will land itself on Duna to supply ground operations. I will be able to lift them two at a time on the Sylph lifter.

Strutting it's stuff on the pad.

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re-entry testing.

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[Speeding Mullet]

Nice progression. I'm really struggling with my SSTO also.

[meyst]

I have been doing experiments with an aim to get an Aldrin Cycler working for the Duna mission.

To do this one flys an orbit that has it intercept with both Duna and Kerbin and an orbital period that is equal to the synodic conjunction of the two planets. Gravity is then used to change the crafts trajectory to set up the next Duna and Kerbin encounters and does this over and over.

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Given the small spheres of influence and the relative proximity of Kerbin and Duna compared to Earth and Mars, I found an aggressive turn was required by some combination of gravity and propulsion. To save fuel I started to test AeroGravity Assist craft to use the atmosphere to help make the turn.

The experiments I have been running are currently showing, 'new challenges'

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Edited August 17, 2013 by meyst

[meyst]

I am finally satisfied with my habitat and rover tests.

Bob testing out the new rover. Comes fully equipped with high quality head lamps, extra science do dads, space seats for four and ample batteries for your Duna driving needs. All on a very rugged chassis with a low center of mass for outstanding stability even during high speed testing. Not intended for tomfoolery and really cool jumps. Kerbal not included!

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The Habit is assembled in orbit by using three launches and docking the components.

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The habit and rover are landed together to operate as a group. Each combination is intended to house two Kerbals and work with a second identical rover/habitat combination for increased safety. The combination comes with a Delta V of almost 1200 M/S, even after landing on Duna this will leave more than enough to handle any inconvenient obstacle blocking scientific endeavors.

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The Rover can be undocked from the Habitat and offer increased mobility for short range missions. Each rover is equipped with four seats but only being assigned a crew of two will be able to rescue a stranded crew. Operating in the vicinity of habitats that are self mobile (on rockets) allows for expanded contingencies and rapid response capability in an emergency situation.

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The Rover/habitat combination can be re-docked while grounded to use the rover to mobilize the habitat over relatively gentle ground, greatly expanding the potential area of operation and allowing rocket fuel to be saved for when it is of the most value.

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Once a habitat has been driven to a desired location the rover is easily freed up for independent use.

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I have made some very minor improvements for the final versions, however they will operate in the same manner, no pictures of this yet because I have not felt the need to test the minor changes.

[Donziboy2]

Interesting use of multiple reaction wheels. Sadly whenever I tried something like that it went horribly wrong.

Also when it comes to flames and reentry, it all depends on how fast you come back down and what angle.

[Commander Zoom]

Nice rover! The hab looks good, too. Any chance of posting a .craft file (for the first, at least)?

[Cydonian Monk]

Out of curiousity, did you ever get an Aldrin/Duna Cycler set up? Or did you find it always needs manual intervention?

[meyst]

I registered on the spaceport and uploaded the Sylph Tarriance, it should be downloadable on the spaceport. You can also downloaded it at mediafire if you prefer. Replace the payload for any payload desired and Enjoy! For engine out capability do not exceed a 4 ton payload.

Cydonian Monk

Out of curiousity, did you ever get an Aldrin/Duna Cycler set up? Or did you find it always needs manual intervention?

Mine required manual intervention. I think even a real one would require some minor manual course corrections to maintain the cycler orbit as any error at all would compound over a long enough time. On a real one even solar wind would need to be corrected for at some point.

In my case I found that to make cycling orbits work I had to make very aggressive turns, such that I needed to fly through Kerbin's atmosphere. I suspect this may be due to the SOI system used for KSP gravity, outside of which the planets gravity has no influence on the space crafts course and/or my lack of a PHD in orbital mechanics.

Edited October 2, 2013 by meyst
Added mediafire link

[Cydonian Monk]

In my case I found that to make cycling orbits work I had to make very aggressive turns, such that I needed to fly through Kerbin's atmosphere. I suspect this may be due to the SOI system used for KSP gravity, outside of which the planets gravity has no influence on the space crafts course....

Both of which break the concept somewhat. Aerobraking obviously can't be done without the ship selected, and the 1-body physics and limited SOIs do change things. (And yes, IIRC, the real Mars Cycler concept involved occasional mid-course corrections. As you mention: solar wind and variable local gravities would throw it off course over time.)

I might still sit down and try the math some day. Suspect the result is the same as what you've discovered.

Thanks.

[Odo]

Your Slyph reminds me of the SpaceX Falcon 9. The Falcon 9 ALSO has engine out capabilities Except it has 9 engines instead of 4 hehe.

[meyst]

I did experiments for a Kebin to Duna cycler orbit, aiming for a duration of 1 synodic period using a solar Ap of 31 305 244 000M and Pe of 13 599 840 256M with an orbital period of 227:09:07:12. Basically a simple free-return trajectory using a gravity turn at Kerbin to align the next leg.

I learned a few things;

Cyclers do work.

Aerobraking to make an aggressive gravity turn cost far less then I expected, the sharper turn also increased gravity assist gains.

Minor propulsive correction maneuvers at the same points on the orbit where reasonable to manage (inclination Ap, correction after Kerbin).

Solar orbit rendezvous with a cycler craft was ridiculously easy.

Cycler craft are great for heavy spacious transit habitats for crew transfers.

They are worthless for delivering supplies and hardware. Hohmann and bi-elliptic transfers are far superior for this.

Ion drive is an attractive option on operational cyclers due to low propulsive requirements and ease of making precise corrections.

As for what counts as a 'real cycler', people much smarter than I am have been putting out papers comparing ballistic and powered cyclers.

[Pipcard]

About that Sylph launcher: so you made a Falcon 9 Reusable, great job!

Edited October 3, 2013 by Pipcard

[zekes]

You need an orbital fuel station. a BIG station...

[Geschosskopf]

@ meyst:

Amazing work on cyclers. I'd never even heard of them before but after seeing your examples, I'm wondering why they're so obscure. It seems like one of those "can't see the forest for the trees" things .

In KSP, however, I guess doing cyclers is a long-term commitment, due to the need to tweak them as needed to keep them going. Kerbal Alarm Clock seems a must.

[meyst]

I have finished working on craft that will supply my long term mission. While it is possible to fly the supply ship direct to Duna from Kerbin using an optimum Hohmann transfer it will instead be transported to Duna as cargo. Transporting it as cargo allows the rocket engine to be used to redeploy the craft to keep pace with mobile scientific operations.

In the assembly building. The jet fuel tank represents 110 Kerbal days of supplies, would last just under a month for 4 Kerbals.

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Entry, Descent and landing pictures (in order)

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No disposing any parts off the lander, such as the heat shield, greatly reduces risk of debris strikes on previously positioned assets. Controlled powered landing (with significant reserves) allows for landings at higher altitudes that are not practical for parachutes and rougher areas with smaller safe landing sites (such as mountain range landing sites).

[meyst]

Sadly I have not had much progress lately due to 'real life stuff' but I do have some modest hardware progress.

I present the Duna orbital power and communications satellite.

These satellites will propel themselves to Duna using witchcraft (Ion drive technology) and maximization of the physics exploit known as 'the Oberth effect'. A propulsive capture will be used to get into orbit of Duna to support ground based mission assets.

Once in orbit a satellite will operate as a communications relay between Kerbin and the Kerbals on the surface of Duna. They will also provide electric power by 'harvesting' photons of light from the Sun and 'beaming' the energy to the ground based assets. Our engineer caution this could allow rovers to make really cool jumps and think it would be better to store the energy using batteries for other uses. Such as running nightlights to keep our brave exporters safe from nightmares.

[meyst]

I have some hardware I wanted to share.

This is the ship I am testing for use as a cycler (Crew transfer ship docked in the picture)

The cycler ship is designed to rotate to create centrifugal force (artificial gravity) for the crew in the habitat. I created a simple (and not very good) slide show so you can see for yourself if you are so inclined (I recommend clicking through the picture menu at the bottom).

Pictures above are the result of construction testing. I constructed it in orbit from a specialized cycler module, three supply modules and an orbital solar array. The five components required three launches of my four ton capacity rocket. I sent up a Kerbal in a crew vehicle to assemble it and was pleased to discover the ship was capable of self assembly. Everything even went together right the first time with no unplanned rapid disassemble, oversights or reports of Kraken attacks.

The craft is equipped with enough supplies for a full return trip all the way back to Kerbin if needed (the jet fuel aft of the habitat). Communications gear, a balanced reaction control system (so the cycler is capable of being the active craft for a docking maneuver). Plenty of electricity provides power for the Kerbals entertainment system and three ion engines (One aft, two on the habitat that are angled slightly away from the hull to prevent fouling of the rest of the craft).

I ended up favoring electric drive for three reasons, safety, thrust to weight requirements, resupply. As cyclers are expected to operate in deep space for years far from home, the fewer moving parts represent a significant risk reduction. In addition the fuel is not corrosive and does not require radioactive materials on board. Once up to speed, the orbit a cycler vehicle will be operating on requires only minor propulsive maneuvers, with plenty of time to set them up. The low thrust on ion engines is also adventurous when setting up multiple gravity assists, in which precision is very important. Resupply is going to be a challenge for any cycler craft. Anything being delivered to a cycler needs to be brought up to the velocity of the cycler, a significant and exponential investment. The high Isp reduces fuel mass considerably. In addition the nature of the xenon fuel would eliminate fuel losses due to the boil off real world cryogenic fuels such as hydrogen and oxygen would be prone to.

Edited February 26, 2014 by meyst