Duna Permanent Outpost Mission Architecture Challenge

[KeithStone]

As far as aerobreaking is concerned, I suppose I'll give away my first tidbit of completed gear for this challenge, my Interstellar Transfer Engine Block (ITEB). Using Droman robotics and LLL, I have a sleek modular heat shield with room above for one unshielded module, about the size of a crew can with a couple docking ports on it. The lower shield protects the sensitive side-panels of the 3 nuke engines. When in interstellar mode, the shields are deployed to make use of the solar tiles beneath them. Hope this helps!

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[sturmstiger]

...

Since 0.21, aerobraking at 12.5km causes the flame effects. Further, it does not put me into an orbit. I suspect I'll also get flame effects when I go to land.

Thus, I would like a little more guidance on heat shielding. Is there a weight requirement? Does the shielding have to go anywhere in particular? Most of the ships I've seen in this thread have the heat shields near the front of the craft. In my experience, ships tend to turn retrograde while in atmosphere. It doesn't seem like the heat shielding would do anything.

...

Hmm...from my experience aerocapture at Duna tend to cause flame effects whereas descending from low Duna orbit generally don't, because it flying through dense atmosphere at higher speed with aerocapture.

The thermal shielding rule (if you don't use deadly reentry mod) asks you to use some otherwise useless parts to shield the rest of your vessel from reentry effect flames. I'm not sure what you meant by "ships tend to turn retrograde while in atmosphere" - it's up to you to place the thermal shielding and adjust the vessel's attitude so the thermal shielding can do it's work.

[ThreeMartiniLaunch]

My apologies, sturmstiger, but I am still having trouble with this.

First, the "ships tend to turn retrograde while in atmosphere". When a ship enters atmosphere, with no SAS or other input, will tend to point ass forward. Try it. Depending on the mass of the ship, how much torque it has, and possibly other factors, you may not be able to avoid this. Try it with a three man capsule reentering Kerbin atmosphere. It will turn retrograde in short order. Bigger ships take longer, it's like they're turning with super weak torque, but they all do it.

That being the case, the logical location for heat shielding is the rear of the ship.

At least one example I have seen in this thread, and I think an early example of yours, used structural panels as a heat shield.

Placing structural panels as a heat shield at the rear of the ship will leave the engine(s) exposed. Is this acceptable? And how much is required?

Is this enough?

This?

Am I totally missing the boat?

I am not trying to be difficult, I'm just having trouble understanding what is required to comply with this rule. Maybe I'm just focusing too hard on this one particular rule. Can I just place some structural panels in an aesthetically pleasing pattern and call it a heat shield?

Thank you again for this awesome challenge and whatever guidance you can offer.

[Death Engineering]

Some designs I came up with for stock-part heat shields. The supply-lander (with the legs) drops onto Duna and uses the fuel cells with the heat-shield tiles. The other designs are panels and adapters. They make great re-entry effects, which is what its all about, right?

[sturmstiger]

My apologies, sturmstiger, but I am still having trouble with this.

No problem, I'm glad to clarify any issue people have with the challenge.

First, the "ships tend to turn retrograde while in atmosphere". When a ship enters atmosphere, with no SAS or other input, will tend to point ass forward. Try it. Depending on the mass of the ship, how much torque it has, and possibly other factors, you may not be able to avoid this. Try it with a three man capsule reentering Kerbin atmosphere. It will turn retrograde in short order. Bigger ships take longer, it's like they're turning with super weak torque, but they all do it.

That being the case, the logical location for heat shielding is the rear of the ship.

I believe the turn has to do with the drag and mass distribution among the parts: just like in real life, the higher drag and lower density parts will be pushed away from the incoming air. However, since you (hopefully) have torque producing parts, you can adjust the attitude as needed. For example, when my Duna payloads enclosed in Dual-Use Shrouds and my Duna Descent & Expedition Vehicle enter Duna atmosphere, I would pitch them up and lock them in that attitude until the end of supersonic flight, just like how the space shuttle and the proposed slender-body aeroshell for Mars are suppose to work.

Source: http://journalofcosmology.com/Mars146.html

At least one example I have seen in this thread, and I think an early example of yours, used structural panels as a heat shield.

Placing structural panels as a heat shield at the rear of the ship will leave the engine(s) exposed. Is this acceptable? And how much is required?

...

I am not trying to be difficult, I'm just having trouble understanding what is required to comply with this rule. Maybe I'm just focusing too hard on this one particular rule. Can I just place some structural panels in an aesthetically pleasing pattern and call it a heat shield?

Using structural panels is a pretty standard way to build "heat shield" with stock parts. My Interplanetary Tug and Duna Transfer Habitat both have heat shields made of structural panels installed at front, just in case they need to use aerocapture in an emergency (they are not intended for reentry normally). I tested them for Kerbin aerocapture (coming back from Mun) and all the visible reentry effects were concentrated on the structural panels (I'll upload a pic later today), thus I would consider the rest of the ship protected. In another word, you should be able to see if you comply with the rule through testing.

[Patupi]

Keithstone? Be careful and do testing on those folding heatshields. In my experience the robotic parts that allow folding don't handle the stress of re-entry/aerobraking well! Most likely the sections will wobble uncontrollably. Make sure to do a test run on this before doing the mission! I know for a fact the rotatatron won't work as I tried this approach myself.

Misanthropia66, as Sturmstiger said, mass distribution is key to re-entry position. Most of the time, empty fuel tanks on the top of the ship, and heavy engines on the bottom mean the drag is in the middle of the ship and mass is to the bottom. Thus the ship pivots to leave the engines towards the source of drag. Yes, if you have sufficient control surface/RCS/torque producing items you can overcome this, but definitely test this.

Another way around it (though trickier) is to place the engines high up on your ship thus raising center of mass above center of drag and then put the heatshields on the top of your ship. Basically you re-enter prograde to get the heatshield aligned. One problem with this approach is that any gimbals on engines won't work right above the center of mass of a ship. They'll actually destabilize and throw a ship's course off! This is a bug in KSP control where it should reverse the gimballing in this situation, but doesn't. Using other controls than gimballing would solve that. Just turn it off and use fins/RCS/torque items etc.

This also means that on a normal ship with engines and heatshields on the bottom that you have to be careful with the position and quantity of heatshields on a craft. If you place too many surfaces down there it lowers the center of drag down towards the bottom of the craft. If you also have heavy payload high up you might find the ship flipping prograde on re-entry as the mass is actually above the center of drag!

Also bear in mind that with the new ASAS in 0.21.1 you may have trouble getting it to automatically stay on heading during re-entry. Honestly I haven't played 0.21.1 much (though I have a version of it installed) as I'm sticking with 0.20.2 for this challenge. Definitely test this before running the challenge!

Edited July 31, 2013 by Patupi
for clarity

[Death Engineering]

Updated some pics and added Mission Entry 5 - Four Kerbals on Duna

Today, Bob continues his dry wit and Ludlong continues to be baffled, we learn that the language Kerbals speak is called 'Kerban', and mission control tries to decide who is going to be stuck on Duna for an extended mission.

Edited July 31, 2013 by Death Engineering

[KeithStone]

Well this is unfortunate...I severely underestimated my laptops ability to handle part counts, and my first simulation of docking several of my assemblies together slowed the physics to a crawl. Darn my trying to cram too much utility in to each lander! Time to uninstall a few mods and see if that helps. Back to the design board!

[Patupi]

I have to admit I'm seriously considering redesigning my Launcher system as when it nears the orbital assemblies things do tend to crawl a bit. I've got a 2.4GHz Quad core so kind of middle of the road. Definitely not a Gaming engine

[Syhrus]

What kind of part counts are we talking guys? I could play a good Samaritan and do your transfers for you. My rig can usually handle up to 750 parts before delta time kicks in.

[Patupi]

Well I think that is actually close. My BHL is somewhere around 500 parts on the ground. Even after the boosters are gone it's close to three hundred. With just one vessel in orbit it goes up to 600. But the Interplanetary ships are in two sections so it's going to go closer to 900 eventually! I'm getting a BHL-6 working now that seems to be 150 odd parts in orbit after boosters are gone. Hopefully I can get it fully working with a 27ton payload and land successfully without raising that too much. With that and minimizing parts on the orbiting sections it should help. Otherwise I may need your help after all Syhrus.

Also I may be posting a little less regularly since I don't have access to my computer as much as before. We've got relatives staying with us this week and my comp is in the spare room. Plus overtime at work eats into KSP time too. Hopefully I can get back in full swing next week.

Wish KSP would run on my tablet!

Edited August 1, 2013 by Patupi

[KeithStone]

Wow, my laptop feels old now. 2.0 dual core, around 200 parts it starts to have issues, and really chokes around 3-4 hundred parts. I also notice a huge slowdown when I use kas, droman, and kethane together, which are my 3 fav mods... Its all good. Just ran the first half of my half-hour transfer to duna to test out the new heat shields and rover rig. I'll get a new laptop at some point!

[Death Engineering]

Yeah, starting to 'feel the pain' with my designs, as well. Between life support and heat shielding, part count over my other designs is "skyrocketing" (hehe). The crew exchange vessel for bringing 4 kerbals to Duna and bringing 4 back from the surface is launched in two parts and docked in Kerbin orbit and has 488 parts and weighs in just under 150t.

[meyst]

It is good to see so many more people joining the challenge and what they are coming up with.

I have decided to restart my planning and will be using a mission reports thread to log my progress.

I have decided to change my lifter from the Gryphon to my new Sylph. It will provide me with a reusable 4 ton to 100x100 orbit capacity, giving a rapid turn around of 6 days between launches.

[KeithStone]

Looks like my wish might actually come true! Sold the old clunker car, might get a new laptop!

[IronGremlin]

Hiya!

I've been following this thread for quite awhile, lurking quietly while I designed my mission modules. I am very nearly done, and ready to start documenting and developing my mission profile. I am super excited!

I had a couple points I was curious about clarifying, if sturmstiger would be so kind:

1) I've developed a really nifty re-useable launch system, however, it does experience some re-entry effects - I am playing with Deadly Re-entry, and the launch vehicle survives re-entry by using its engine as a heat shield. (I use a combo of B9's Aerobrakes and some probe torque to keep it pointed engine-side down). Additionally, the launch profile is such that I actually have time to circularize and then switch back to my final lifter stage to manually land it. Does that still count as re-useable?

2) Does the use of Ion-cross preclude the rule about supplies entirely, or are you simply allowed to ship Ion-cross oxygen containers as if the were supply units?

I could see that going either way, although, I will say, actually needing to be concerned about the oxygen that your kerbals are consuming while in transit most definitely adds another layer of difficulty - The mass of enough oxygen to survive a Duna transfer drastically exceeds the amount of mass you'd need to ship up in abstracted RCS supply units for the same period of time, and any manned off-window transfer attempts are incredibly difficult.

3) Assuming I am using Remote Tech, can I launch my initial Kerbin relay satellites for without re-setting my launch window timer? I really enjoy how much challenge Remote Tech is adding to the actual Duna mission, but it seems a bit punitive to include those first few launches as part of the general launch limitations.

Thanks!

[Patupi]

Welcome to the Duna Party (Not to be confused with the Donna Party) Iron Gremlin. Best wait for Sturmstiger's official approval, but as far as I know the only question on re-useable is does 50% of it survive to land again. I think if you're using Deadly Re-entry mod he won't have a problem. I'm currently playing with a few launcher designs myself and one possibility is a third stage on a almost totally re-usable system, with the rest on a ballistic course, landing on that continent to the east of KSC. Actually, from testing, I doubt I'll use that configuration, but I'm pretty sure it's allowable. It does leave a low part count at orbit however, but I'm currently testing a much lower part count vessel over all, though some does splash down rather than land *shrugs*

I doubt he'll have a problem with Ioncross oxygen containers either, but you might want to try Thunder Aerospace's WIP Tac Life Support. I've been following that since I noticed it a couple of days ago. It models life support needs even when the ship is not player controlled! It's still being developed but looks very promising!

As to remote tech, you might consider a manned launch on day ten with multiple control sats docked to it if he doesn't allow a pre-emptive launch of the sats. Though I doubt he'll have a problem with sats in Kerbin orbit prior to day 10. Duna orbit perhaps.

[sturmstiger]

Hiya!

I've been following this thread for quite awhile, lurking quietly while I designed my mission modules. I am very nearly done, and ready to start documenting and developing my mission profile. I am super excited!

I had a couple points I was curious about clarifying, if sturmstiger would be so kind:

1) I've developed a really nifty re-useable launch system, however, it does experience some re-entry effects - I am playing with Deadly Re-entry, and the launch vehicle survives re-entry by using its engine as a heat shield. (I use a combo of B9's Aerobrakes and some probe torque to keep it pointed engine-side down). Additionally, the launch profile is such that I actually have time to circularize and then switch back to my final lifter stage to manually land it. Does that still count as re-useable?

2) Does the use of Ion-cross preclude the rule about supplies entirely, or are you simply allowed to ship Ion-cross oxygen containers as if the were supply units?

I could see that going either way, although, I will say, actually needing to be concerned about the oxygen that your kerbals are consuming while in transit most definitely adds another layer of difficulty - The mass of enough oxygen to survive a Duna transfer drastically exceeds the amount of mass you'd need to ship up in abstracted RCS supply units for the same period of time, and any manned off-window transfer attempts are incredibly difficult.

3) Assuming I am using Remote Tech, can I launch my initial Kerbin relay satellites for without re-setting my launch window timer? I really enjoy how much challenge Remote Tech is adding to the actual Duna mission, but it seems a bit punitive to include those first few launches as part of the general launch limitations.

Thanks!

1. Deadly Re-entry can completely substitute the stock reentry rule which is based on reentry visual effect. In another word, if the parts survived reentry with Deadly Re-entry, then they are considered good for use (and reuse) even if there's reentry visual effects.

2. Ion-cross can also completely substitute the stock supply rule, which is how it is used some current entries. See my reply to KeithStone in Post 146 for details.

3. Yes you can launch Remote Tech Sats completely independent of the rest of your missions. They are not restricted by the rules of challenge as long as their purpose are to provide comm relay. It is assumed that before the crewed missions there were already a number of probe / robotic missions which had done preparatory work such as surveying landing sites and building a communication relay system.In fact, you are welcomed to present the outpost missions as a stage of a larger Duna exploration program, proceeded by various orbiter, lander, rover and perhaps sample return missions, although only the outpost missions will be scored for this challenge.

[Death Engineering]

Posted "Mission Entry 6 - Bob Loses his Rover", where Bob's rover winds up in Macly's possesion, Jeb and Bill head out to Duna to visit Bob and Mission Control gets good news about the future of the Duna Space Program.

[Patupi]

OK, during testing of the replacement for the BHL series (this seriously no longer is 'bulbous' so the name will have to change) I've ended up with a ship where the final, disposable booster hefts the payload way up beyond 75km. This could be imbalancing. The way I'm reading the rules set the stated payload is for reaching low Kerbin orbit 'or parking orbit'. I know the DV difference between 75km and 100km isn't much, but I suspect my current ship could probably deliver it higher than that. I punched an orange fuel tank (more than the rated 27tons load) up to 100km and still had quite a bit of fuel left over in the last stage. Doing this I feel is stretching things a bit.

I'm going to see if I can redesign this down a little, but should there be a range you'd accept? 70km to 100km? Going much higher will cut back the DV requirement to get to Duna, which means the payload can have less fuel for the trip... it all escalates quite quickly. I guess with the need to keep fuel for returning my old reusable systems back to Kerbin safely I never pushed to see how far up they'd chuck the payloads. Never thought how it could mess with this.

(EDIT: BTW, my new launcher is only partially re-usable now. To get a low part count on the last, third stage it's non-resuable, and even the second stage is just a dropped fuel tank. The first, reusable stage is large, way more than 50% of the ship (6x seperate orange fuel tanks) and jettisons after the gravity turn, thus are over water and have no need for landing gear. They have no re-entry glow and then splash down nice and easy at less than 7m/s with no damage at least. They should come down in a fairly reliable spot for the KSC navy to recover I believe)

Edited August 3, 2013 by Patupi

[meyst]

Patupi, this is my opinion and obviously Sturmstiger has the final word.

If your using your lifter to push the tonnage you state into reasonable orbits, I don't see any problem. Obviously if someone is understating lifter capability and/or using a high thrust to weight lifter with the intent to exploit the ability to push heavy cargo that circularizes itself, that is an issue. I think exploitation like that would get noticed by Sturmstiger and handled accordingly.

[Patupi]

I'm trying to cut back my lifter without compromising it right now and will be launching to 80km as a standard (some variance due to piloting error I haven't used mechjeb on ascent in a while). I was really just wondering for others once I noticed this. I guess it was just the '75km or parking orbit' whatever a parking orbit is that lead me to ponder that someone might take things a bit far. I think taking out the second drop tank stage might actually strengthen my ship. It was a little wobby. And having an orange tank as the third stage instead of an... oh, is it x200? I forget, the next size down from the orange tank... anyway, that's not going to increase the part count at orbit so I think that'll work.

[sturmstiger]

OK, during testing of the replacement for the BHL series (this seriously no longer is 'bulbous' so the name will have to change) I've ended up with a ship where the final, disposable booster hefts the payload way up beyond 75km. This could be imbalancing. The way I'm reading the rules set the stated payload is for reaching low Kerbin orbit 'or parking orbit'. I know the DV difference between 75km and 100km isn't much, but I suspect my current ship could probably deliver it higher than that. I punched an orange fuel tank (more than the rated 27tons load) up to 100km and still had quite a bit of fuel left over in the last stage. Doing this I feel is stretching things a bit.

I'm going to see if I can redesign this down a little, but should there be a range you'd accept? 70km to 100km? Going much higher will cut back the DV requirement to get to Duna, which means the payload can have less fuel for the trip... it all escalates quite quickly. I guess with the need to keep fuel for returning my old reusable systems back to Kerbin safely I never pushed to see how far up they'd chuck the payloads. Never thought how it could mess with this.

(EDIT: BTW, my new launcher is only partially re-usable now. To get a low part count on the last, third stage it's non-resuable, and even the second stage is just a dropped fuel tank. The first, reusable stage is large, way more than 50% of the ship (6x seperate orange fuel tanks) and jettisons after the gravity turn, thus are over water and have no need for landing gear. They have no re-entry glow and then splash down nice and easy at less than 7m/s with no damage at least. They should come down in a fairly reliable spot for the KSC navy to recover I believe)

If your launcher can send an orange tank to 100km circular orbit then it shouldn't be rated 27 ton, UNLESS you never send anything more than 27 ton to your LKO parking orbit (100km is okay). Reducing the payload capability of a launcher should be easy - just use a smaller tank.

As you said The current rule on LV's nominal lift capability has loopholes: the "LKO parking orbit" is indeed vague, and allowing the "payload" to do the final circulization burn is also open to exploit. There are in fact many places in the rules which are exploitable, but I don't think people doing this challenge will try to exploit them, thus I'm not going to try close them all which will make the rules unreadable. The challenge is intentionally quite permissive, but if I see anyone taking things too far with a loophole I'll let them know.

[Patupi]

I understand, and I'm using an orange fuel tank merely as a useful test piece. It's a bit bigger than my rated load so if I can heft that to orbit I should be fine with my rated load. I've got my design now able to launch the orange tank up to 72km and leave enough on the third stage to de-orbit (burn up), so I'm thinking sending 27tons to 80km should be fine. The only trouble I might have is lack of width. Before I was bracing from far out to hold the payload on some wide Duna tranfer vehicles stationary during launch. May have to increase inter-part bracing in compensation which may push the part count up. Here's hoping it doesn't skyrocket.

Catalyst launcher. Part count 237

And after the boosters separate, at about 40km (they are still at low velocity so no re-entry effects when they go down- EDIT: OK, they jettison at 20 to 25 km, but have an AP of ~40km when ditched) Part count 111

Note the 2nd stage engines are LV-T30, not LV-T45 so no vectored thrust. Once the payload is ditched the center of thrust could easily be above center of mass and flip control via VT engines, so no gimbals. With the torque wheels it still rotates fine.

Edited August 3, 2013 by Patupi

[Psycix]

Patupi, having the CoM lower than the CoT does NOT automatically stabilize your rocket. It's a common fallacy:

http://en.wikipedia.org/wiki/Pendulum_rocket_fallacy

Also note that with thrust vectoring, having your CoT close to your CoM gives them less authority, just like control surfaces far from the CoM are more effective.

But it shouldn't be a big deal as long as your reaction wheels can stabilize the craft.

Edited August 3, 2013 by Psycix