Dash 4 Duna - Duna Permanent Outpost Mission Architecture Challenge

[DBowman]

This is the mission report for my entry to sturmstiger's Duna Permanent Outpost Mission Architecture Challenge http://forum.kerbalspaceprogram.com/threads/31510-Duna-Permanent-Outpost-Mission-Architecture-Challenge.

I had been making some prototype and proof of concept craft and kept going back and forth between things I wanted to play with and the scoring scheme. Cool realistic features like safety (what astronaut would settle for less) and mobility (an astronaut can sit in a can at home) all cost Primary Score. I couldn't find a good reason to weigh one against the other.

While watching Kubrick's Dr Strangelove I was inspired to an all out Primary Score effort.

SAY NO TO A RED DUNA! DASH 4 DUNA

In a UN speech the Krussian Premier Khrushchev drunkenly boasts "We will bury you!". The incident is widely reported and the world laughs at our impotence.

...

A spy within the Komunist space program reports the Krussians have advanced plans for a permanent Duna base of unknown size.

...

Secretary State Kissinger advises the President that 'we cannot afford a red Duna! we must preempt the Krussians with our own even more ambitious program!' - How ambitious? 'we just don't know, we'll have to go all out'

...

President KFJ addresses the nation setting out an ambitious new space program: "We chose to do this thing, and some others, not because it makes sense - but because we must be first"

...

General Keck Turgidson is appointed to head the program. Engineering says it can deliver on two of fast, cheap, and safe. Gen Keck practically explodes out of his chair "Two? Two! You WILL deliver three - fast, fast, and fast! I don't want to hear any of your Hohmann bat guano. Burn early, burn hard, and burn often!"

- - - Updated - - -

This is essentially a stock 0.25 entry, but (of course) with a few mods:

• I used MechJeb, Kerbal Engineer in flights.
  
• Traj for the neat display of orbit predictions including atmosphere interactions, double check with alexmoon for aerocapture and Mechjeb for landing predictions
  
• HyperEdit for "Numerical Simulations" to test aero-capture landings etc
  
• Procedural fairings for the heat shield.
  
• Deadly Reentry and a few other reentry mods are installed. I'm not using them (not really 0.25 compatible ) but I didn't want to mess about getting DREless craft into a 'clean' install.
  
• KAS - I use some 'pipe ends' for transferring supplies.
  
• Life support is RCS. Any RCS you see is "supplies", all docking is RCS-less.
  

Edited March 8, 2015 by DBowman

[DBowman]

Here is my 30 ton to 100 km orbit more that 50% reusable lifter with a 'test payload':

• VAB & Pad details
  
• staging
  
• safe splashdown of stage 1 boosters
  
• de-orbiting of stages 2 & 3 for 'tidy'
  
• final 100km orbit
  

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This will support 30 ton to 100 km orbit every 45 earth days starting on ED 10.

Edited March 8, 2015 by DBowman

[DBowman]

To maximize Kerbals on the ground we minimize mass - so I went for aerocapture. I'm sure the Kerbals enjoy the shock plasma outside the window also.

I used procedural fairings for the heat shield. Here are some "numerical simulations" comparing various kinds of shield; none, too-small, just right, just wasteful, & nominal with 6 Habs tucked behind it.

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I ran test entries up to about 5km/s at the Duna SOI, even 'coming in hot' on a non Hohmann transfer they only pull a 'few' (8?) Gs. I don't think I even need that velocity but nice to know they can survive the capture, the parachutes opening is more brutal (15G!). Also if the mass distribution is 'bad' it will flip over and lead with the payload!

Edited March 14, 2015 by DBowman
spelling

[DBowman]

To maximize payload I had to go Ion, it's kinda painful but it just makes sense.

Each interplanetary flight consists of Ion thruster modules, a heat shield, a payload, and transit supplies. Transit supplies are designed to be consumed en-route and jettisoned, Xe for the transfer burn and RCS for the crew. The first image is the payload-less thruster and heat shield Duna-Kerbin return configuration.

For those not familiar with low thrust transfers here is the flight profile:

• I used alexmoon's transfer calculator (http://alexmoon.github.io/ksp/) to know what to expect and when to time the initial burn to have the pre-escape orbit close to the right angle.
  
• Make a series of few minute burns, for my craft about 3.5 mins for 80 m/s delta v each burn.
  
• After about 9 of these and 4 Kerbin days your orbit is Ap-ing near Munn distance and you are ready for the final burn.
  
• I just picked the simple method of setting a maneuver node in the middle of the 'falling to Kerbin' side (where everything is still happening slowly) then tweaking time to start the burn and the delta v to get an encounter.
  
• Finally burn for ages, after SOI adjust, fine turn on Duna approach, fine fine tune in Duna SOI for aerocapture.
  
• Aerocapture with Ap between 50 & 100 km, you will impact after the Ap.
  
• After the capture you can use the atmosphere to lower your orbit without needing the heat shield, the thrusters will be doing this.
  
• Jettison the shield and half the thrusters, they dock and thrust as a unit to get a safe Pe. Each thruster will have about half a Xe tank left - enough to get home.
  
• Tune the payload Pe so that it will land where you want, I went for Lon 84 in the big flat smooth depression south of the volcano.
  
• Jettison the remaining thrusters, they will thrust to a safe Pe & rendezvous with their siblings and the heat shield.
  
• Open the chutes, at the 'last possible moment' burn the landing engine for a soft landing.
  

I'm doing a Kerbin-Duna transfer one launch before and one after the Hohmann window, so 3 transfers each window. I can tune the payload by trading off Supplies for Xe depending on how much delta/v is required.

Soft landings are via a combination of parachute and Rockomax 48-7S with minimal fuel. I started out with 4 radial parachutes per Hitchhiker for a fully passive landing costing 600kg, but a single chute slows it to about 25m/s and needing only a little burn at the end. With passive landing I could have independent Hitchhikers, but I was aiming for something flyable so I thought to stick them together and then found they needed less than one chute each. I settled on about 1 chute & 1 engine per pair, about 250kg for landing.

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There are four payloads, each consists of a number of Hitchhikers and the remaining mass budget in RCS supplies. There 6, 4, 2, and 0 Hitchhiker configuration, the 4 & 2 configuration are mobile, 2 can be used to ferry supplies around the surface.

The 6 Hitchhiker payload.

• 6 stacked in a triangle to be compact & low to the ground
  
• solar arrays on the 'edges' to minimize self shadowing and so you can yaw the craft to maximize solar exposure
  
• thrusters coupled to the payload
  
• 3 parachutes & 3 Rockomax 48-7S for a soft landing.
  
• surface supplies are down low for 'balance'
  

The 4 Hitchhiker payload

• 3 750 RCS for supplies
  
• 4 hitchhikers
  
• wheels underneath
  
• 4 chutes & 3 48-7S for landing
  

The 2 Hitchhiker

• a supply wagon with detachable Hitchhikers
  
• rove to the 'base camp', dump the Habs, then be a supply shuttle
  
• 4 chutes & 3 48-7S for landing
  
  

The 0 Hitchhiker

• a supply dump, no wheels
  
• 6 chutes (symmetry) & 3 48-7S for landing
  

Edited March 14, 2015 by DBowman

[DBowman]

The planning algorithm is:

• Use the Kerbin launches one before, at, one after the Hohmann window for Kerbin-Duna transfers.
  
• Push as many Kerbols to Duna as soon as possible without actually letting them run out of supplies.
  
• Zero redundancy.
  
• Zero margin for error.
  
• Duna ascent & crew interplanetary transfer vehicles will be sent 'later'.
  

I've used ED for Earth Day per the game version of the original challenge, & KD for Kerbin Day per version 0.25 that I am using.

S = supplies = RCS

ED 10 : KD 40

Flight 1

6 Hab 101 ED of total supplies

landed

t+KD 277

ED 79.25 : KD 317

landed supplies = 750 + 9*50 +12 - 12*69.25 = 1212-831 = 381S

12 Kerbols on Duna, dead in 381/12 = 31.75

dead by ED 111 : KD 444

ED 55 : KD 220

Flight 2

4 Hab: 3*750S, 300 xfer supplies = 37.5 ED,

2900m/s Xe, can get a 2300m/s encounter

landed

ED 90.5 : KD 362

=> 35.5 ED flight

Duna residual supplies = 12*(111-90.5) = 301

Landed supplies = 3*750 = 2250 (had to discard a little in orbit)

20 kerbols on Duna, dead in 2551/20 =125.55 ED

dead by ED 218.05 : KD 872.2

ED 100 : KD 400

Flight 3

2Hab + 4*750S +4*50S +6*50S (for transit)

landed ED 189 : KD 756

Duna residual supplies = 17.75*20 = 355

landed supplies = 4*750+200-60 = 3140

24 Kerbols on Duna with 3495 supplies

dead by ED 334.625

ED 235

Flight 4, 5, 6 - all leave with Flight 6, one 'slot' before the Hohmann window

2*6Hab

1*4Hab

landed ED 305

Duna residual supplies = 29.625*24 = 711

landed supplies = 2*(381) + 3*750 + 300 - 8*70 = 762 + 2550 - 560 = 2752

56 Kerbols on Duna with 3463 supplies

death by 366.84 ED

<- ED 257 Duna-Kerbin return Hohmann window. Kerbin by ED 321 F1,2,3 return components can go.

ED 280

Flight 7

0 Hab, Supply only

landed ED 315.5

landed supplies 4740 => +84.643 EDays

56 Kerbols on Duna

dead by ED 451.47

ED325

Flight 8

0 Hab, Supply only

landed ED 414

landed supplies per Flight 7 => +84.643 EDays

56 Kerbols

dead by ED 536.113

ED460

Flight 9, 10, 11

landed ED530

so the mission can continue through to day 1000 but these flights land outside the 500 day mark and don't contribute to the 'Early Mission'

Early Mission Value: 15840

= (500-79)*12 + (500-90)*8 + (500-189)*4 + (500-305)*32

= 421*12 + 410*8 + 311 * 4 + 195 * 32 =

= 5052 + 3280 + 1244 + 6240

= 15840

Early Mission Efficiency: 48

= 15840 / 330 / 1

= 48

Edited March 31, 2015 by DBowman
/ 30 / -> / 330 /

[borisperrons]

56 kerbals on Duna at once? Wew, talking about space cities XD