Mod Virgin - Career playing with "Better Than Starting Manned"

[Death Engineering]

If you're taking suggestions, may I say Duna. The re-entry performance from a 54km orbit ablated about 300 units with an aggressively steep angle. Chute tweakables do the rest. If you can get Ike to troll, even better.

[Dave Kerbin]

Duna is a strong contender. The delta-v requirements for Moho make it a bit too steep unless I can think of a really fancy design o it's really hard to pick it as a first choice. The other contender is Eve/Gilly and that would depend entirely on the return of my probes. If I get enough science from the probes to Eeloo/Jool that a Gilly mission would put me over the top then it would make a good first stop since having even one tier 9 tech would make the other manned missions easier. However if a Gilly mission isn't going to give me an extra part then it's not really worth doing immediately, better to do one mission and unlock something.

My Duna reentry concerns aren't really about the heatshield, even in stock I consider Duna a relatively easy planet to visit in terms of fuel and such but at the same time one of the most risky because there are single moments that will make or break the mission. On Eve/Kerbin/Laythe you deploy parachutes and that's it. On bodies without an atmosphere it's a simple matter of burning and there is no drag to worry about messing with your alignment. On Duna there is enough of an atmosphere to make a pure rocket landing complicated, but not enough to make a parachute landing straight forward. The real thick stuff that you can use for semi-deployed parachutes doesn't start until you are almost hitting the ground (there is a wide canyon I try to aim for because it's the only place that you have a few good km of thick air overhead). That means you don't have a lot of time for the atmosphere to slow you down before you hit the ground so you'll be traveling fast when you open the parachutes. And Duna's atmosphere is thin so you'll need a lot of them which just helps to make parachute release and full deployment very risky. You risk crashing into the surface because you didn't deploy in time, you risk the chutes being ripped off because you where still going too fast when you released them, you risk the ship being torn apart when they fully deploy because they had no time to slow you down so you where going too fast, and finally you might still hit the ground going too fast because even the chutes have a hard time slowing you down. And then when you thrust a bit to cushion the landing you risk tipping over the lander (in my previous career file I almost lost my Duna lander when it bounced on touchdown and the RCS was only just able to catch it from flipping)

[FlowerChild]

I personally find drogue chutes really help for pulling a Duna landing for the very reasons you mentioned. Yes, they're annoying in terms of being inline only, but I find a well placed hub part can take care of that.

[Dave Kerbin]

Donut 2

I want to get this one down quick so I can look at updating to BTSM 1.5, which updates the tier 9 tech level along with some other changes. Donut 2 is a mission to Eeloo, something which was planned from the start for the Donut series (the Donut lander has way more delta-v then is required for just Dres). I did find that the transit stage might be a bit short for Eeloo, the ship's delta-v vs. trip estimates where a bit close so I made modifications to the transit stage to extend the delta-v by about 1500 m/s while increasing the weight by a little under 5 tons.

The radial tanks are doubled in size while the center drop tank is reduced to keep the weight under 60t. The radial tanks are now detachable so the fuel ducts are in an asparagus arrangement to increase range. The lander remains untouched even though I have a better antenna. Since it required a lot of arrangement to get all the parts on the lander weight balanced and able to fit on the small surface without visually blocking the RCS thrusters I didn't want to start all over again. For the next series of probes which will go to Jool I'll have a revised design.

Reaching Eeloo won't be easy, it's on an inclined eccentric orbit that takes it far from the sun and it's SOI is not very large so with a little help I write down a detailed mission plan just before starting up the game.

The injection burn is on the night side of Kerbin so there is not a lot to see. In fact a lot of this mission had poor lighting. To get enough delta-v a lot of the rocket is shed off in stages resulting in a drastic weight and size reduction between LKO and deep space. The center tank and half the radial tanks are discarded before the coasting phase can begin.

This is going to be a long trip. 220 days before the first course correction which will bring Donut 2 onto an intercept course with Eeloo which will then be followed by some smaller burns as it gets closer to refine the approach to less then 60 km of Eeeloo's surface. Even after the course correction it's another 310 days to reach Eeloo. A manned mission will need a lot of supplies.

The course corrections use up the fuel in the 2nd last pair of tanks, leaving me with one last set for capture. Orbit is also polar, running along the line between night and day. Orbital scans reveal a 3x multiplier - I'm getting the feeling that regardless of distance all planets except Kerbin have 3x for orbit and all moons except for Kerbin's are 2x.

After all the orbital scans are complete the ship begins disassembling itself for the landing. First the mapping sensor and reaction wheel for transit maneuvers is removed. Then after burning some remaining fuel to push its course toward the day side for landing the transit engines are discarded followed by the generator.

On the surface it's a big multiplier, 15x just like Eve. Of course Eeloo is my final destination so I don't know how much that will help on a manned mission.

[Dave Kerbin]

Grape 1-3 (Part 1...)

I didn't miss F, but the mission with that letter was 95% ready and I didn't want to shuffle the names because I liked how they fit. Anyway Grape is a short or long mission depending on how you look at it. I want to find out the value of the long term habitation study so I have numbers to use in determining it's value for a given manned mission. It's going to take 5 years to complete so I might as well get it started now and run other missions, even at maximum timewarp it will be a long time to complete. The Grape station will orbit Kerbin (putting a station around the Mun or Minmus wouldn't provide any benefit, I'd need to go into the complexity of setting up a base on the surface to get a higher multiplier and I want to know the value before I invest in that) at 80km.

Since I'll need a lot of supplies for 5 years (seriously, that's a long time. What are the kerbals learning in 5 years that wouldn't be learned in 1?) the ship is split into 3 pieces weighing just under 60t each (my 180t booster is not ready yet). The first piece into orbit contains the living space, return pod, power generator (including a basic battery backup), deorbit engine and a nice chunk of supplies. There is not much to the first section, it's launched into orbit and the solar panels are aligned for year round coverage.

To last 5 years I'm launching two identical modules, Grape 2 and Grape 3. These originally looked cooler and even had a minor excuse to use the big radial engines, but after some changes to simplify docking alignment in relation to the solar panels (originally it would have been one long station) the requirements for size became drastically simplified. While Grape 1 goes to considerable length to pack in as many supplies as possible without blocking the solar array's line of sight the extra modules ultimately didn't need to so a nearly empty orange tank was used as a structure for simply attaching the required supplies (I had some extra weight left over so I evened out the number of supply canisters). Grape 1 also uses empty fuel tanks (T800s) for it's shape.

Before docking the nose cone needs to be disposed of and the booster is also discarded for a poodle engine with a enough fuel to intercept. The main propulsion though is the large monopropellent tank (I haven't used one of these in a very long time) and some balanced RCS thrusters which I also haven't done in a long time. There are thrusters balanced on both ends to allow it to rotate or translate without affecting the other. For rotation and lateral translation it includes the new higher power place anywhere RCS thrusters which make it a very maneuverable 60t craft. Speeding up or slowing down isn't nearly as fast unless I use the poodle engine, so I'll need to watch that.

Again the RCS system makes it very easy to move around. Grape 2 slides up beside the main module and closes in on the docking port (there are also 2 secondary docking ports in case something comes up later). Grape 3 docks while the dark side of Kerbin, so there isn't much to see even with color enhancement. Each supply ship carries an additional 4000em in battery capacity, both to provide plenty of time to setup an intercept and to provide backup for the station. After docking the probe cores are shutoff to avoid wasting power.

With all the modules docked the experiment begins. In 5 years we'll know something, until then Nedvan Kerman will sit in a seat looking out the side window (the center window is blocked by the study equipment and return module).

[FlowerChild]

seriously, that's a long time. What are the kerbals learning in 5 years that wouldn't be learned in 1?

Loss of bone density. Long term radiation exposure. Other long term health effects. Basically all the stuff modern astronauts and cosmonauts are learning the hard way.

It's not just five years sitting around. It's five years of prolonged torture followed by what is an almost certain death

Edited March 28, 2014 by FlowerChild

[Dave Kerbin]

I'm still working on stuff, just not any time to fly.

For Jool I've had a probe built in the VAB for a while called Fish 1 but I may scrap/redo it now. The goal of Fish 1 was to perform orbital surveys (2Hot, PresMat, GravMax and Mapping) of most or all of Jool's moons. Previously I've combined orbital mapping with a lander but Jool has some special cases that make me want to get all the orbital data done with and then do the landers. The most important special case is Laythe. Laythe's atmosphere provides one of my best chances for a big science return (only Tylo's surface might provide more return) but frankly it poses placement issues to design a jack of all trades probe that does mapping and atmospheric studies. Making things worse is that to really do a proper Laythe study I'd need to set down on one of those small islands which means I'll either be building a fancy lander (maybe even a mini jet!) or having a mothership with an atmosphere probe and several very cheap parachute landers so that I can make several drops in the hopes that I can hit land with at least one.

Pol and Bop are the second special case. Rather then seperate and send down a lander to each individually I'd prefer a single lander that makes the hop between them. A finally Tylo will demand a rather large lander so removing the mapping equipment and power supply would help. Fish 1 was similar to the Donut series but it removed the lander portion, added more batteries (recharging from the NUK NUK is really only practical while making deep space transits) and shifted the fuel stored on the bottom so it could be replaced with an inflatable shield for Jool aerobraking. The ship would have about 3000 m/s to explore Jool's moons with.

However I've been thinking about manned missions and my efforts on a 180t lifter had some poor results. The first stage is still occasionally shaken up on first being loaded, resulting in a lost fuel tank (though the design is so stable I was able to subsequently take off on a test flight even with that tank and engine missing) and the 2nd stage has a reoccuring problem when it tries to level out and complete the initial burn, the engine or tanks facing the ground getting torn off by stress. Since I'm not going to save scrum my missions until I get a good launch I did briefly consider leaving it as a non-manned rated booster. I could send up my ship without a crew (and lose some hardware every couple of launches) and then use the super-stable 30t lifter to bring up a crew shuttle after.

That got me thinking back along the lines of replenishment ships and I plugged in some quick numbers to find out that using my existing boosters I could design a 'truck' (I've got the prototype complete in the VAB now). The truck fits on the 60t booster and flies into orbit where it docks with the 60t payload from another launch (that payload could be a resupply module containing fuel or life support, or a manned spacecraft, or even another truck!). The truck then provides the engines and fuel for 2000 m/s. That's enough to fly and brake at Duna (no heatshield required), fly to Jool (a heatshield would be required) or fly to roughly Gilly orbit around Eve (no aerobrake required).

The truck will likely recieve it's first test run when I finish redesigning the Fish mission to take advantage of a full 60t probe in Jool orbit (the truck will put the 60t payload on track to Jool then be discarded to reduce the body needed to be protected by the heatshield). From there I've made some napkin calculations that show a single truck could provide transport for my Eve orbit/manned Gilly mission. After that Duna might require multiple trucks - the fact that a truck can carry a copy of itself means I could actually fly one to Duna to be used to bring back whatever has to come back.

[Daddy Cecil]

Not sure about this, but perhaps you could install the FASA launch clamps. It seems like a pretty good supplement to stock launch clamps, with stack clamps, umbilicals, a launch tower (!) and a regular old super-sturdy clamp. What I mean is that this could improve the stability of your 180t launcher.

[meve12]

Can the trucks return with a 30-ton payload, or does it have to be lower?

And can trucks be stacked to pull larger payloads farther?

[Dave Kerbin]

Can the trucks return with a 30-ton payload, or does it have to be lower?

And can trucks be stacked to pull larger payloads farther?

I'd have to work it out but my guess it could return with a 30 ton payload, probably more since you'd be reducing the payload while keeping the same quantity of fuel. Trucks can't be stacked as there is only one proper attachment point. In reviewing mission designs and the requirements for a truck-truck flight I've found that doing that might be more trouble then it's worth - I'm having a hard time coming up with a near future mission that will want to return 60 tons of payload to Kerbin. It seems more likely that the return vehicle would be part of the initial payload. For example if I want to do a Duna+Ike misson the most likely layout would be a pair of 60t payloads which would both get hooked up to their own truck to be sent off to Duna. One payload would carry the kerbal, all the life support he'll need for the whole mission, and the return rocket and reentry system. Basically if anything goes wrong that module could fly him back to Kerbin safe and sound. The unmanned payload would contain landers for Duna and Ike and possibly a tug for moving between Duna and Ike orbit (I haven't reviewed my data on the travel time from low Duna orbit to Ike, it might be better to just build a big Ike lander that can do the whole journey itself). After making the landings any science equipment to be recoveryed would dock with the manned module and the remaining pieces of the unmanned module would be discarded before the burn to return to Kerbin.

I've been going around and around on figuring out my Jool mission profile. Without using a bunch of hubs or some weird layouts I don't see a good way to integrate so many sensors that all want to be stack mounted (multiple sensor nose cones and the mapping sensor). I did design some micro probes that would fit on the hub part but then I need to take into account weight balance so I can safely burn from one orbit to another. For the moment I've gone back to just upgrading the fuel on Fish 1. It will do all the mapping/orbital work and then I can come back with studies for each of the moons and a descent probe for Jool itself. One mission I'm trying to figure out a good target for is some kind of unmanned interplanetary return mission (Goo containers). I want to make a trial run using the inflatable heatshield to make an interplanetary Kerbin reentry before I actually send out a manned mission and have to rely on it working to get him home safely. I could reduce the complexity of a manned Duna mission by collecting all the Goo data and bringing it back with an unmanned probe.

[Dave Kerbin]

Very small update here. I'm been busy but I copied over the .23.5 update (my steam edition is always mod free) and did a really short check in. In stock KSP the new big parts look interesting and I slapped together quick rocket with whatever looked cool (new clustered engine at the bottom with 2 of the biggest tanks and 2 of the new liquid boosters, then an upper stage with the big single nozzle rocket and finally a conventional poodle orbital stage with a capsule and the new launch escape tower). It turned out to not have enough thrust in the 1st stage once the boosters ran out, the launch escape worked great. However I also really noticed the stability improvement. I went over to the mod side and briefly tried launching my experimental 180 ton lifter which seems to fly without issue now. This will probably change things, as interesting as a transit module like the truck may be if I can just launch 180 tons right away I might switch it for a reusable assembly instead.

[Dave Kerbin]

Fish

I've been going back and forth on this mission. The changes in KSP have making the design of lifters in the end game perhaps a bit too easy. I've thrown together a few larger boosters and currently have a 120t transit system; it can move 120 tons from the launchpad to a Jool or Dres intercept (or into orbit around Eve or Duna). That's a bit overkill and confused my plans for an initial Jool probe. Ultimately I wanted to send something so I came back to a rough copy of my original 60t design (which would have been carried to Jool by the seperately launched 60t transit 'truck'), just placed on the bigger booster to simplify design. Because of how the Jool capture works the extra delta-v won't get used, and because I still have some concerns over how effective the inflatable heatshield will be it limits how much I really want to attach to the probe. With all the extra delta-v going to orbit and setting up for a Jool intercept isn't really interesting. The probe's mission is to explore Jool itself and the only moon with an atmosphere Laythe. This will let me get all the sensor nose cone readings out the way - I find the instrument a pain to work with because of the mounting restrictions so I'll be happy when I have every bit of possible data it can collect.

On the way to Jool a minor burn is made to bring the probe's inclination into match with Jool. Entering Jool's SOI the probe is on an intercept course for Tylo. The PE is lowered to the target of 119 km, during which there is also a brief intercept predicted with Vall. Shortly before contact with Jool's atmosphere the transit stage is ejected and the main Jool heatshield is deployed. The is a second solid heatshield behind it - that heatshield has another purpose but it's secondary job is to protect the instruments on the top of the probe in case the inflatable heatshield doesn't provide enough protection (I'm not sure about how long a cone of coverage the heatshield will give). There are some small radial fuel tanks and I debated whether they should have decouplers - not for better delta-v but so that if one was destroyed by heat I could eject it's matching tank and rebalance the weight. Ultimately I decided the decouplers would increase the risk of the fuel tanks being exposed to entry heat more then the rebalancing would help negate it. The transit stage still has it's radial fuel tanks/engines attached since I didn't need all the delta-v but I needed to get rid of it anyway to let the heatshield open up. I manually skipped a step in staging so I wouldn't have 6 fuel tanks flying off radially, releasing the transit stage as a single piece so I could easily use RCS to put the probe on a slightly different descent and remove any chance of a collision. The picture required a lot of brightness enhancement to see anything.

I had intended to try an orbital scan during the low pass around Jool. This was based on the mechanic that unless you where on a suborbital path you where consider to be in orbit (in previous versions of stock this prevented you from getting atmosphere data from Eve just by skimming past). However here it seems I could get atmosphere data while aerobraking which prevented me from using the mapping scanner long enough to get a reading. I proceeded to do all the high atmosphere readings in addition to the basic orbital readings I'd already taken. During braking the heatshield turned orange and then white hot. The secondary heatshield remains cold. For transmitting I used the antenna directly behind the heatshield which fully protected it (it is behind the inflatable heatshield at the top).

After coming out from Jool's atmosphere I moved some charge around in the batteries since I had just performed some mission items out of order and was unable to complete the mapping scan. The AP is near Laythe's orbit as planned and as the probe nears it alignment is made for seperation. After ensuring all systems are turned on (they had been in hybernation during transit) the Jool heatshield detaches, taking with it a probe designed to explore deeper. The Jool probes core and engines are aligned opposite that of the main probe. The smaller probe burns a bit to seperate, in the process lowering it's PE for the next Jool pass. The larger probe intended for Laythe is already pointed in the opposite direction, raising it's PE above Jool's atmosphere.

The Jool descent probe is mostly hollow being built around a decoupler and engine fairing. It has several hours of battery life to take it back to Jool for a final descent. Enter Jool's atmosphere readings are taken - while orbit was the same 3x found everywhere outside of Kerbin the atmosphere is a valuable 9x, bringing in a lot of science for this descent.

There are two drogue parachutes and I didn't know if they would be needed - I was unsure of how long the probe would last before it was crushed in Jool's atmosphere. Because of that I activated them fairly early so they could deploy when the atmosphere was thick enough. At a certain point both parachutes suddenly exploded, taking out one of the engines with them -I think they might have deployed, momentarily shifted the probe and been destroyed by the massive reentry heat (I recorded heatshield temperatures exceeding 4500 C). Long after I'd gotten my readings the probe continued to fall, slowing to less then 50 m/s even without parachutes. Things started getting really weird at low Jool altitude. The RCS stopped having any effect (I could see the thrust but the ship couldn't turn or rotate in any way). The single engine could still sort of move the ship. Then the ground partially disappeared and when the probe finally reached 0m it kept going for another few seconds before exploding.

Coming back to the Laythe probe it seems it's already on a course for Laythe so a adjustment is done to correct inclination and lower PE to 100 km. However reaching Laythe's SOI I encountered a major problem. I had budgeted 2800 m/s to reach and capture around Laythe in low orbit. While I saved most of my fuel with the free intercept my speed is giving me a cost of over 3500 m/s to capture. At this point at least one of my Laythe experiments can't be done, the map scanner. The seismic scan is also is serious danger, as I needed a stable orbit to even attempt an accurate landing on one of the small islands.

I use my fuel to kill as much speed as possible while altering my PE to about 25km. The probe will hit the atmosphere at about 3.5 km/s but before then I'll take what orbital readings I can. Laythe is the first body I've found whose orbit has a multiplier higher then 3 - it is 4x.

Entering the atmosphere the engines, remaining rocket fuel and functioning nuclear reactor are safely released where they can harm nobody. The descent probe has a few placement issues, I thought I had gotten the decoupler in the proper orientation and the communications dish slightly clips a sensor when it is open. The biggest issue is that the dish seems to stick out from the heatshield, but apparently that has no negative consequences and it transits data about Laythe's atmosphere which is worth 5x. The braking is not quite enough to capture the probe on the first try - it falls to 25 km, then rises back up to 35 km before gravity and drag finally win and it descends for a second scorching. The parachute system works though not entirely as planned. The craft flips over and descends upside toward the ocean (the nearest land is far over the horizon).

After a safe landing the probe is able to right itself automatically and transmit some basic information about the surface. A water landing means the Double-C can't be used which is a shame because the surface of Laythe seems to be worth 15x. I have just over 6200 science, so this mission provided about 3700. I think I'm in range that a manned mission to Duna could provide me with the means to enter tier 9.

[Jacke]

David, I'd like to express my appreciate of your BTSM career playthrough thread. Although you're far in advance of my own game (especially as I decided to restart to check out the changes in the lower tech levels), seeing how things happen later on is both entertaining and informative.

[Dave Kerbin]

Ham 4 (Part 1)

The numbering for this mission is a bit messed up, it even confused me to the point that I might need to skip over a number for the next mission due to a mistake I made midway through. The first 3 Ham ships never left the ground: the first two I tinkered with different fuel tank layouts in the VAB and the 3rd was a final configuration held down with launch clamps for a fuel line test to determine if the arrangement I had made would confuse KSP (it did - having multiple fuel ducts that eventually lead to the same destination causes weird things to happen).

Ham is built on top of my 120t transit assembly but instead of being a payload that discards the transfer stage I made extensive modifications to integrated it into the ship itself (the one restriction was that I couldn't change the bottom fuel tanks and engines used without taking apart the entire booster assembly). The result is a ship designed to travel to Gilly, Duna and/or Ike with about 160 days of provisions and a solar array capable of powering it at the range of Duna. Since all of these destinations have been covered with probes it is designed mainly for manned science. It carries 2 Goo containers itself (for orbital readings) and assumes that a lander will provide a biometric sensor and a dockable payload consisting of a Science Jr and another 2 Goo containers. With some of the destinations I listed provide more opportunities to use Goo containers my numbers showed that science wasn't crucial to reaching my next level of development.

The first Ham ship will travel to Gilly. Gilly will stress the fuel load more then Duna since there are a number of variables that would alter just how much delta-v gets used (what angle I approach Eve at, etc) but provides less stress on the life support consumables and the solar array which hasn't been tested in space yet. If there where problems with array coverage I could get away with only 50% of the panels receiving power for a Gilly flight. But the most important reason was for science - after going to Gilly and Duna I want to unlock the RTG, and that means I need to meet a certain amount of science. The science I will get from Gilly is relatively fixed - there are a few opportunities I am skipping but there just isn't enough there that I can 'expand' the mission plan to gather more if a mission to Duna comes up shorter then expected (maybe I miss a reading or lose a piece of equipment). However if I come up short in a Gilly mission then I could simply restructure the Duna mission to pick up the slack. In the worst case scenario Ike could provide all the additional science I need (I considered a Duna+Ike mission to get the science for the RTG but for personal reasons I wanted to go to Gilly too).

I'm sending Johncan Kerman on this mission and I've loaded Ham with a Gilly lander (I've already designed the lander for Duna so that I'd know the weight in advance for fine tuning Ham's fuel load). The launch is straight forward though at 330+ parts in the lower atmosphere I actually got a slowdown in the game speed, a limit I haven't hit before. The first stage is a massive 24 mainsail monster to reach about 15km. After that the 2nd stage with 7 mainsails takes over. This stage has some small fins to counter spin at this stage of the flight. I had to ease a bit on the throttle due to the lighter load and prevent buffeting.

Just before the cutoff the 2nd booster is exhausted and the orbital engines takes over. This was designed to include up to 500 m/s of delta-v for orbit and circularization but I only need about 30 m/s to reach a 100 km AP and another 110 m/s to circularize. The orbital portion has an asparagus staging - all engines initially draw fuel from the 2 large side tanks. Once those are exhausted the 4 smaller side tanks are used until it is just the center tank and a single engine, by which time the ship should be on a return course. The 6 engines (later 4) provide a large amount of thrust. With the exception of the return burn (when it reaches a single engine) the ship can perform injection and course corrections with burns of less then 3 minutes each.

The injection burn to Eve goes well and thanks to a safety margin and the fact that far less delta-v was used from the orbital tanks to get into proper orbit there was till over 1300L of liquid fuel left in the two long side tanks. However now that the ship is on course to Eve those tanks need to be ejected. The ship is given a bit of roll and then the tanks are released to drift away. With the tanks removed the solar array can be extended. The ship continues rolling until the array is lined up with the sun. The side tanks can block the solar panels if the tail end of the ship is pointed roughly toward the sun. The ship needs to be aligned to point in the rough direction of the sun. The solar system is able to operate at full efficiency which will be required to reach Duna.

Edited April 12, 2014 by Dave Kerbin

[Dave Kerbin]

Ham 4 (Part 2)

In deep space on the way to Eve some biometric readings and crew reports are taken. This is bonus science in addition to what was already planned. During the trip the ship requires a few attitude adjustments to ensure the solar panels can continue tracking the sun without being blocked. Arriving at Eve I find myself in one of my classic bad Eve approaches. I'm passing on the wrong side of the planet and I'm doing it on an inclined path. A 560 m/s capture burn is made that brings me into a heavily inclined retrograde orbit high above Eve. Some more readings are taken here and one of the motherships Goo containers is used. There is no planned visit to low Eve orbit.

From this point I started to wing it in regards to getting into Gilly orbit. I've gotten myself out of this situation a few times so I'm a bit more comfortable make a series of manuveurs without being able to look far ahead at the result.

The first burn is 260 m/s to tip my orbit over a bit so that I'm technically on a prograde orbit and I'm going to come fairly close to Gilly. After that burn I fast forwarded until I was crossing Gilly's orbit path. At that point I didn't plan a maneuver, I just pointed myself at the target indicator, then tilted myself off a bit in relation to the prograde marker and burned about 2000L of fuel. This brought me into am orbit close to that of Gilly's and bit behind it.

From here I used regular maneuver nodes to adjust my inclination (another 30 m/s) and then setup an intercept for another 9m/s that would bring me to Gilly in about 3 days.

Because my orbit is so similar to Gilly's the capture is incredibly easy (5 m/s) and I've got ages to do it.

In high Gilly orbit I take some more biometric readings and a crew report, then expose the 2nd Goo container on the mothership. In part 3 I'll be setting up a surface expedition.

[meve12]

Why'd you ditch all that extra fuel?

[FlowerChild]

Why'd you ditch all that extra fuel?

If you look at the initial screenshots, the solar panels are resting under the external fuel tanks and he needed to ditch them to extend the panels.

[Dave Kerbin]

Why'd you ditch all that extra fuel?

Because they where mounted over the same section of the ship as the solar array - I couldn't deploy it until those 2 injection tanks where discarded. One of the designs that never left the VAB experimented with placing the solar panels on a pair of the external tanks but that ran into issues. The number of panels needed to generate the required power at Duna's distance from the sun meant that they would need to be larger tanks (like the big injection ones). And since those panels would be essential to running the life support system I'd need to keep those 2 tanks attached for the entire flight, which means I'd be dragging around empty orange tanks. Even with adjustments to fuel flow it would still mean that I'd be giving up efficiency on the return stage by carrying two additional massive tanks and engines and I finally just didn't like having such an essential system mounted to a radial decoupler.

The flight plan was built around the idea that the fuel in those tanks would only be used to reach orbit and perform the injection burn to Eve/Duna. All the other delta-v required was accounted for in the other tanks. The reason there was so much fuel left was mostly because the launch was so efficient leaving me with about 400 m/s extra in addition to the safety margin (the tanks where designed to provide both a 500 m/s suppliment to the boosters and then another 1000 m/s for injection). With the heavier Duna lander attached the launch should use up more fuel so those tanks will be nearly empty when they are discarded on the next mission.

[meve12]

Oh.

I crit-failed my Sherlock Scan.

[Dave Kerbin]

Ham 4 (Part 3)

The Gilly lander is a bit unusual, it's not an optimal design in a number of areas and it precludes the collecting of crew reports (I factored that into my science numbers before the mission). I mainly did it because it would be interesting in relation to the additional restraints there are in BTSM. Since the gravity on Gilly is so low it is trivial to land with RCS only. That got me thinking about a truly minimal lander and that meant removing the cockpit. Now normally I don't use the command chair even in stock but here it provided some interest - while in the chair the kerbal is relying on their spacesuit's life support system which only lasts for 15 minutes. This would mean I would need to be able to complete the mission in that time.

I went through a few descent/ascent profiles in the planning stage. My initial thought was to get into low orbit, then have the lander fly ahead of the mothership and land so it could then launch and be almost caught up with it so that it could dock without an orbit. However I anticipated some problems with how to navigate that course (which direction to burn on the navball in order to get 'ahead' of the mothership even if the mothership was on a likely inclined orbit). My solution was to park the mothership. Not in orbit but over the landing site.

The mothership is brought into low orbit (about 5km, it can't stay here long without risking a collision with terrain which is about 3.5km below right now) where crew reports and biometric sensor readings are taken and one of the goo containers on the lander is used. Then the mothership makes the burn to kill all orbital velocity as if it's going to do a direct landing (on Gilly there isn't much velocity at all to kill). Then I switch to surface mode and make a second smaller burn to roughly line up the prograde/retrograde markers with the top and bottom of the navball. This means I've canceled out most of the relative motion between the ground and the ship so that to an observer on the ground the ship is floating in place and slowly descending instead of cruising past. From here I perform the last step: with the ship pointing straight up I make a little burn so that it is now flying upward but not enough to escape Gilly. It should reach the AP in about 6 minutes and then start falling back down. Since the mission must last less then 15 minutes that should keep the ship parked long enough.

(Remember that Gilly is rotating so by the time the ship is coming down on the other side of the arc the ground will have moved and the ship will still be over roughly the same area)

I turn on a probe core that has been kept dormant during the mission in order to keep the mothership aligned with SAS. I don't need a freely rotating ship when I come back to dock. Next Johncan goes on EVA and gets into the seat. He opens the valve on the landers monopropellent tank and sets the control from here to a tiny probe core just under the chair. The probe core itself is disabled (more on that later) but it helps to properly orient the navball since the chair is not aligned to anything useful. Finally he released the motherships docking clamp and seperates. Some RCS is used to push out laterally and then a hard push is made to get the lander moving downward at about 20 m/s. (in hindsight it would have been safer to also close the solar panels so there wouldn't be any risk when I came back up to dock, there is plenty of battery power)

Now about that probe core. When I designed the lander I knew that I would need SAS to dock it. With the extremely light mass and the way I was placing the thrusters there was just no way I could reliably dock it with no SAS under a tight deadline (given lots of time I could do it by just setting up a long approach and treat it like RCS'less docking). I also wanted that control from here point so that I could land with the navball line up intuitively though I had an alternate way of getting that (replace the tiny decoupler with a tiny docking port). The way I planned it in the VAB is that both the probe core and it's 10em battery are disabled. I then setup action group 0 to toggle both the battery and the probe core, essentially turning 0 into my T key for toggling SAS with the small restriction that I'd only have about 5 minutes of SAS time. In a 15 minute mission 5 minutes would be all I would need. However there is a small bug in stock I stumbled on that is know to FlowerChild in which even a disabled core will provide SAS. I think this might be the only situation where it is possible to actually exploit that (since all the SAS probe cores are lighter then their counterparts). Could the command chair be given SAS, since it's been said in the past that pod SAS is just the kerbal doing the piloting?

With my velocity relative to the ground already in order landing isn't much trouble. I cut my landing speed to under 2 m/s and the lander bounces a few inches and slides sideways on the landing gear a few more feet before coming to a rest. In the low gravity the lander does have a bit of trouble maintaining a hold on the surface, after landing it wants to lift off on one foot. My supplies are at 33.5/50 monopropellent and 13.4/18 life support. The second Goo container is exposed and the biometric sensor is used. Johncan then gets off and uses his jetpack to reach the surface. He can't really walk here so it will need to stay on the whole time. A surface sample and EVA report are taken before he moves to the Science Jr. When he is done he pockets the data disk from the biometric sensor since it won't be coming back. I did make one big blunder during this operation. I was already juggling around the names and icons of the pieces I had and I accidently labeled the flag Ham 5 instead of Ham 4. For that reason I'll probably skip to Ham 6 for the Duna trip just to avoid confusion.

The ascent portion of the lander takes off from the makeshift launchpad and heads up toward the mothership. As I get close I use control from here to switch the navball to the docking port on the bottom. Since the mothership's docking port is facing up I'll brake as I'm passing it and then come back down from above. As I'm braking just below and to the side of the mothership (3rd screenshot) my supplies are at 25.8/50 monopropellent and 6.7/18 life support. The mothership is currently falling toward the surface, with my ground markers now present I can see it is less then 3km to the surface.

I take a little more time then planned to get lined up properly (I was approaching but it was obvious I was laterally off so I slowed down rather then miss). I discovered I was having the trouble because my speed indicator was still set to surface (in orbit it would automatically switch to target when you get close enough) and since I dock by instrument first and sight second it was throwing off the approach. This close to the docking port I'm now down to 2.8/50 monopropellent and 3.1/18 life support. I finally got lined up close enough but the lander was 'circling the drain' - the docking port magnets had taken grip but the port wasn't finding the exact center so the lander was wobbling in a circle on the rip of the docking port. I didn't know it at the time because I focused on docking but I'm down to less then 1 unit of monopropellent and I used some more to gently push the lander down to settle it. Final monopropellent is 0.8/50 when docked. Once docked the spacesuits battery immediately begins to recharge however the life support is still being used. The first thing I do, now that I'm in control of the entire mothership is to fire the engines a little in order to boost it back into an upward suborbital path. Then Johncan can get out of the chair and board the pod where he can drop off the surface sample, EVA report and the disk from the biometric sensor. The final life support is 1.9/18 when he boards.

Some house keeping is done at this point, checking the systems and turning off the probe core. The ship is turned a bit and then the tiny decoupler on the lander is fired, removing the last of the manned equipment and leaving only the recoverable experiments docked to the mothership (the chair and thruster equipment are still on a suborbital path and will crash into Gilly). An odd artifact of how the game decided what was a probe and what was the original craft is that my MET has now reset - it no longer shows that the mission has lasted over 40 days but has reset to 0. The mothership burns a few more m/s to break free of Gilly and enter a stable orbit around Eve. The only step remaining now is to return to Kerbin.

[Dave Kerbin]

Ham 4 (Part 4)

The ship is intended to return immediately to Kerbin - there is no point using up life support sitting in Eve orbit. My pre-planning showed a 60-odd day return from Eve but I couldn't seem to find it. I was able to find a 89 day transit instead that would take the ship outside of Kerbin's orbit. The Duna capable solar array will be needed for this portion of the trip. On the flip side the burn isn't very expensive at 1227 m/s though I have tons of fuel at this point (the center tank alone was designed to provide a final 3000 m/s for a safe return burn). The burn is on the other side of Eve's orbit so it will be a 2 day wait before it is executed.

The side engines run out of fuel about a third of the way into the burn. There are no fuel lines so they are draining fuel at the same time as the center tank. They've provided about 400 m/s but now they are dropped and I sit in for a long burn on the center engine. The original time estimate with all 5 engines was 1:50, but with the thrust cut by 80% another 3 minutes is added. It's still under 5 minutes so the Ham ship is still quite speedy.

In deep space a 180 m/s course correction is needed to fix up my approach (my initial burn wasn't accurate enough to actually get an encounter, just a close intercept) and to bring my estimate PE to less then 200km. The real challenge during the transit is keeping the solar array aligned during the large sweeping flight around the sun. With all the external tanks dropped the weight is far more balanced from end to end which means I actually have a lot more RCS thrust then I need. You can see that the tail end of the ship has massively overengineered RCS thrusters to counter the weight imbalance during the early stages of the mission. Place anywhere thrusters for pitch and yaw and 2 sets of regular thusters for rolling.

Arriving back at Kerbin the final PE is lowered to 25 km. My experience at Jool showed me the inflatable heatshield can take a massive amount of punishment so I calculate the risk being greater if I don't aerobrake enough then if I aerobrake too much. I also transfer life support from 4 of the containers into the pod, refilling it nearly to capacity. The pods monopropellent tank valves are also opened and finally the recycler is turned off - with all the life support transfered to the pod it can last for days but once it is seperated from the mothership it will be on batteries so I want to reduce consumption in case the aerobraking captures but doesn't deorbit the pod (resulting in the pod potentially orbiting for several hours before a second dip in the atmosphere).

At 400 km the pod decouples from the mothership. The heatshield is inflated and aligned for reentry. Orbital velocity is about 4000 m/s and rising as it approaches.

A little bit of RCS is used to actively keep the ship aligned. It would probably align naturally by weight but I don't want any risk from it shifting to find that sweat spot. The heatshield easily protects the ship and enough velocity is lost to put it on a path to land.

With speed at under 500 m/s the heatshield is discarded. At 6km the parachutes are deployed for final landing. Despite lacking a parachute the heatshield survives landing.

The mission provides plenty of science, Duna will easily provide enough to unlock the RTG. Something I may take into consideration for Duna is adding an additional pair of life support containers. With the unexpected longer trip from Eve I may need to plan for a similar situation for Duna. Delta-v shouldn't be a problem though I need to be very careful with the solar system. Additional batteries for safety might also be advisable.

[meve12]

Have you considered making a spacestation for transfering crew, fuel, and science to/from the VAB? This would allow for reusable interplanetary mssions.

[Dave Kerbin]

Have you considered making a spacestation for transfering crew, fuel, and science to/from the VAB? This would allow for reusable interplanetary mssions.

I probably wouldn't use a spacestation for it. If I had the energy to keep going with my .23 career and do the big engineering missions (where I would be limited to 4 LV-Ns with which to do them all I think) then I would have built a refuelable, reuseable nuclear tug that would park in Kerbin orbit where new drop tanks would be attached and 2 payloads would be attached - the mission payload and the return capsule.

In this case there really isn't much of a need to reuse the ship. I can put it into space with a single launch and the drop tanks are much easier to work in when they use decouplers and struts instead of something that has to be locked on exclusively with docking ports and still fly stable. There is also the amount of reuse it would get - I only intend to fly one more mission with the Ham interplanetary ship before I unlock RTGs and the design is retired in favor of one with a 100% reliable and renewable power source. After Duna my destination will likely be Eeloo so I can wrap this up. I haven't worked out exactly how that mission will work. One idea I have is to launch 2 ships with a similar mass and engine configuration as Ham, the first one unmanned that would fly out to Eeloo and park there and a follow up manned ship. There are a few ways I could use two ships - the unmanned ship would almost certainly carry a lander and could include a fuel pump to refuel the second manned ship. An alternative design would see one ship used to reach Eeloo (with the higher delta-v requirements) where it would meet the lander and the ship that would be used to return home.

[FlowerChild]

If I had the energy to keep going with my .23 career and do the big engineering missions

On this point, just in case you missed it in the BTSM thread: the current versions of the mod are backwards compatible with those from .23. I haven't done a save-breaking release yet, so restarting for .23.5 content isn't really a necessity at this point.

[Dave Kerbin]

On this point, just in case you missed it in the BTSM thread: the current versions of the mod are backwards compatible with those from .23. I haven't done a save-breaking release yet, so restarting for .23.5 content isn't really a necessity at this point.

I'm actually refering to the .23 career in my sig, .23 Career (Science on a budget) . It's a stock career and was my second career save after the one I created for .22. I laid out a series of missions before hand though it turned out that science was much easier to get and I had to impose further 'budget' restrictions to try and keep things interesting. I lost interest in the last phase - the final 3 missions with the entire tech tree unlocked where basically big engineering missions (major Laythe mission, 2 man mission to Moho, manned mission to Eve) and I just don't get interested in those. That's why I'm looking to reach my goal of Eeloo in this save, then I can call it finished and start playing a fresh save with the updates you've made.