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

[Dave Kerbin]

Chandrasekhar 1

With access to liquid rockets but without decouplers or RCS thrusters this rocket represents something of a stepping stone between suborbital missile like probes and true orbital satellites. In theory it has enough power to get into orbit but the technology limitations mean it wouldn't be a very good or reliable way of doing it though as you'll see it comes very close. It is somewhat large for a basic orbiting satellite but then it lacks any way to seperate stages, so there must be enough engines to carry all the dead weight, and in turn enough fuel to power those engines. Basic operation is very simple - all the engines start at the same time, then cut out as their fuel supply runs out. You can see this splits the engines into 3 groups based on how much fuel they have. The layout of the engines, in particular the 3 with the largest fuel supply, is deliberately along the east/west axis to support some experimental guidance. The payload includes the GravMax and enough power for 2 transmissions.

A gravity turn is started using the fins but it can only go so far. The gravity turn needs to take advantage of the thinning air but at the same time this reduces the effectiveness of the control surfaces. At launch all the engines are tweaked to 80%, this prevents them from overheating even with the throttle at 100%. As the ship climbs and the fins become useless an experiment is conducted to determine if thrust control can be used for a gravity turn. While far from a perfect control mechanism the experiment proves the technique is viable - for example to lower the nose the engine thrust for the east side engine is lowered for half a second, then as the ship begins to nose down it is put into overdrive to cancel out the rotational velocity before being returned to 80%. Since this was still being worked out the ship overshot it's orbital target with an AP of 138km, the gravity turn was not completed within a good timeframe so even with fuel remaining there is not enough for the 800+ m/s that would be needed to make proper orbit. A circulization burn is made anyway (if only to extend the orbit and ensure good opportunities to use the GravMax), using a very small amount of thrust to help rotate the ship into alignment for the manuever and it comes within 300 m/s of a stable orbit.

A pair of GravMax readings are taken of the ocean and grasslands before the ship begins reentry. Since it was nearly orbital the ship enters the atmosphere at over 2 km/s causing it to burn up. There are 2 techs that I want for spacecraft development - RCS for control and decouplers to bring up larger payloads. In order to get RCS I'll need to unlock the capsule and parachute and I have enough science for one of the two major techs. When I designed Chandrasekhar 1 I included the ability for RCS to be added later without the need for additional fuel. It was my plan that Chandrasekhar 2 would have RCS control and be able to enter stable orbit. However with the success of the thrust control experiment I decided it would be more useful to send up a ship with more batteries so that it could transmit GravMax readings for more then two biomes, and that means using decouplers to make a more efficient ship (yes it could be done without decouplers but that would be a giant ugly thing that abused the joints too much). So the next ship will be designed with decouplers to bring up more battery power; I need to cover at least 3 more biomes around the equator and could get some extra science by boosting into high orbit.

[PeterPan]

The idea of maneuvering the vessel by short thrust reduction is brillant! Glad to read a new missions report. I like the mission's naming too

[Dave Kerbin]

Drake 1

Drake 1 carries enough battery power to transmit 4 GravMax reports and is staged thanks to the new decoupler. It carries a fair amount of extra delta-v in order to facilitate using thrust moderation to turn and actually needs more fuel and engines then normal for this kind of payload because of the need for the final stage to carry 3 engines/tanks. However issues begin appearing very early in the flight. While Chandrasekhar tipped a bit in the compass direction it was stable along its own axis. However Drake does not appear to be stable (possibly because of the small bit of flex where the decouplers link the stages, possibly because Chandrasekhar was much wider) and has a small bit of spin. In the lower atmosphere this can be corrected with the fins and I struggled to keep it nulled out. By the time I ran out of air for the control surfaces the spin was practically nothing, but even a tiny bit was enough to seriously throw things off as soon as I started trying to turn with thrust - in the second shot the ship should be going to the right but thanks to the rotation combined with the use of imbalanced thrust it is now rotating around.

I made an effort to get it into orbit, or at least a useful suborbital path where it would pass over some mountains, but these efforts where not enough. It never reached space, preventing the GravMax from being used in any capacity. Drake 1 final broke up as it passed over a mountain range.

[Dave Kerbin]

Chandrasekhar 2-3

I need some more science and I'd rather not waste money trying to make thrust control work 100% so it's back to plan A. I'll need one more suborbital flight to get the science to unlock RCS instead and then I can go ahead and upgrade Chandrasekhar for proper orbital flight. Chandrasekhar 2 flies like the first one, only I'm directly it a little west so it will pass over the highlands and mountains while in space. With the science from those two biomes I unlock flight control as I maybe should have the first time instead of pushing to far ahead for more battery life.

Chandrasekhar 3 is the promised modification that simply adds a monopropellent tank and RCS thrusters. With these modifications Chandrasekhar 3 is easily flown into a polar orbit to grab the Tundra and Ice Cap gravity readings.

A desert reading might be possible in terms of orbit but not in terms of power - after transmitting the second batch of data the ship has only 80em of charge left, enough for 8 minutes of operation and just short of actually reaching the desert much less transmitting information. In my previous game I collected a lot of debris in orbit - I only pointed it out a few times but it became almost a certainty that I would pass near some debris while launch and even some interplanetary returns passed within 20 km of orbital debris. So I'm going to try and clean up as much garbage as possible this time. I can't quite reach the AP so I setup and burn the last 8L of fuel about 2 minutes before I'll run out of power. That lowers the ship to a 56km PE, but by then dumping the contents of the monopropellent tank I lower that to 37km with 8.07em left. As it enters the atmosphere the ship slowly breaks up piece by piece. Realtime it took 30 seconds before the probe core exploded but I've sped it up. Apart from the pieces sitting in the field west of KSC I have left no garbage so far.

I now have enough science to unlock Science Tech which gives me a bigger battery, pressurized cockpit and goo container.

[Dave Kerbin]

I like the mission's naming too

Some of the upcoming names are getting hard to pick. The next mission name was a narrow win for Eratosthenes (the tie breaker being that I don't know how many ancient era astronomers I'll be able to fit in so I'll take one when I can) but I can't decide if the one after that should be Fleming or Fraunhofer.

[Dave Kerbin]

Drake 2

With the Goo containers my next objective is easy to see. I'll want to expose 4 of them to the pair of biomes in the atmosphere and Kerbin orbit and then return them safely to the ground. Since I'll be visiting high orbit I might as well record temperature data too. I did some quick figures to see what kind of ship would be needed but quickly found that the Drake class, designed to carry a large quantity of batteries but shelfed due to the stability issues, fit my needs. It also possessed two important attributes, it used decouplers so it limited the amount of weight that had to be returned but at the same time it also used a 3 fuel tank final stage (because it was designed for thrust control). I need the radial tanks as a place to mount parachutes. So the Drake design was dusted off and most of the batteries where replaced with Goo containers, parachutes where added and finally the same RCS control unit added to Chandrasekhar 3 was added to Drake 2.

Ascent is straight up and while Drake 2 has the same spin instability as Drake 1 it doesn't impact things since the RCS system can keep it on course.

Goo is exposed to the atmosphere on the way up and as the ship enters space the AP reaches 260km and the engines are throttled down. Drifting into high orbit the last 2 Goo containers are sampled and the 2Hot readings are recorded. On the way back down RCS is used to hold attitude and at 80km traveling 1.4 km/s the engines are throttled up again to start braking. At 40km the speed has been reduced to 300 m/s for a smooth reentry and the engines are cut again. The parachutes are already armed (they where staged to arm as soon as the 3rd stage engines lit up since by then the ship would be well above the 6km deployment altitude). It looks like the ship is descending into the mountain range west of KSC.

Normally my 6km parachute deployment isn't an issue - only the highest points on Kerbin are that high and my opinion is that if you land there you'll most likely be destroyed rolling down the mountain. As you can see the probe can very close to the mountain, it is just reaching the 6km point for parachute deployment but has already passed the nearby peak. Fortunately the probe misses the peak and the parachutes deploy, though some RCS was used to help keep the probe aligned to minimize the shock when they semi-deployed. With all the weight speed is still 17 m/s with the chutes fully deployed so some engine power is used for a gentle touchdown.

I think I received 8 science for returning my first object safely to the ground in addition to the 150 for the Goo and 8 for the 2Hot. The science is invested into the first small engine and fuel tank (completing tier 4) and then Space Exploration for the mercury style capsule.

[Dave Kerbin]

Eratosthenes 1

This is the first manned mission of the new program. Thanks to your voting the first candiate was selected and has been undergoing training for this mission. I'd like to introduce the 50% brave Aldrick Kerman.

The ship itself has a fair amount of delta-v just for safety sake if I need to bring him home quickly or otherwise recovery from an unforeseen situation. I also have a potential secondary mission to use some of that fuel but it will depend on how long it takes to complete the primary mission of low orbit observations. At this point I don't think there will be enough remaining life support to attempt it as the pod carries only a little over an hour (and I'd prefer to use anything past the 60 minute mark as a safety margin). With Aldrick piloting I have SAS so launching is easy. The second stage is fired up just as the gravity turn starts. I slightly underestimated the average ISP the T15 engines would perform at in the atmosphere leading to the second stage being enough to get all the way into orbit (it was planned that the third stage would provide about 100-200 m/s).

In making sure the first launch was a success Aldrick missed the atmospheric crew reports. This won't be a big issue, they'll be collected on the next mission. Aldrick begins making observations from low orbit, spotting the ocean, shore, grasslands, highlands and mountains. Nearing the end of his first orbit he passes over the desert where he makes both a crew report and activates one of the GravMax instruments. There are two of them in case the Badlands are spotted but like everytime they are not. There where a few momentary glimpses of the oddly placed Tundra though no crew reports where made in time.

At this point 30 minutes have elapsed and life support is almost half depleted. A second orbit would be risky on life support supply so plans are begin to deorbit. Aldrick is aiming to return to the KSC, since it was the only inhabited area he observed during his entire flight. The return burn finishes up the second stage allowing the third stage to kick in. This is useful as it also simplifies reentry by removing the bulky 2nd stage ahead of time and leaving it far behind (though the last orbital projection before staging showed that it should enter the atmosphere and impact somewhere on the far side of Kerbin).

Reentry goes as planned - the RCS thrusters don't seem to mind - and the parachute is deployed at 300 m/s to slow down and land close to KSC.

After a soft landing the capsule with an alive and well Aldrick are recovered. I'm not spending the science yet, I'll be making a second flight on a polar orbit. Since that flight should cover it's intended biomes in about 15 minutes I should have time to expand it to high orbit and get an observation there. It will also be a chance to pick up those atmospheric reports too.

[Dave Kerbin]

Eratosthenes 2

This is a second manned flight to fill in the parts that couldn't be covered by the first. Thanks to voting the second kernal picked is Kenby Kerman. I'm noticing that there is a strong relationship between votes and how stupid the kerbal is. Fortunately if things hold out the 3rd and final kerbal will have been picked for his courage.

The design of the ship is the same except that the GravMax sensors have been removed for this flight. The goal here is a pass over in the poles from orbit and a visit to high orbit. To do this I burn to put the initial AP past the north pole and in high orbit, accomplishing both objectives in a single orbit. Technically it's not even an orbit though, since there is no specific need to burn at the AP to raise the PE high enough to avoid reentry at the south pole.

Passing over the pole and taking readings I realize that my polar orbit is very close to passing over the exact north pole, as evidenced by the rapid vertigo inducing camera movement as the auto camera passes over the pole. Reaching high orbit another reading is taken just as the sun begins to fall behind Kerbin. Coming back into the light over the south pole the ship also begins reentry. A final report is taken of the upper atmosphere since I forgot to grab it (a lower atmosphere one was taken during the initial ascent) and then the service module is jettisoned.

Reentry and splashdown occur without incident and the pod is recovered with Kenby and his reports. With just over 400 science accumulated I can unlock several 90 point nodes. I unlock Landing which provides the Double-C instrument, ladder segment and probe landing gear. I unlock Advanced Flight Control which gives me a new rectangular probe core that's twice as energy efficient along with SAS, Reaction Wheel and a regular sized monopropellent tank. Aerodynamics gives me the first heatshield, a larger parachute and some various aerodynamic parts. Finally Advanced Construction gives me the Docking Port, size adapters (big to small, small to tiny) and Struts.

[Dave Kerbin]

Fleming 1

I've dried up most of the science on Kerbin (if I could find the badlands that would be 55 but I can never find them) so it's time to go farther. I understand that BTSM now has antenna range - each antenna has limits to how far away it can transmit science from and still be received by KSC. That won't be an issue for the first mission beyond Kerbin's immediate vicinity as I will be landing a probe on the Mun and return samples of Goo exposed there. This time around my booster designs are coming across a big square. Part of this is because I haven't unlocked an engine with more thrust, another is that I simply needed 3 tank rockets early on for the mounting space and I've just sort of stayed with them. I'd like to think that if I used some part clipping and the tail section piece (I don't remember if that's even in BTSM) that I could smooth out those square edges - they should naturally be curved to form a smooth rocket in a manner similar to many Soviet designs. The gravity turn is executed immediately after the first stage booster is discarded. This second stage is intended to take the ship to within 300 m/s of a stable orbit and carries it's own monopropellent supply. A difference from the first placethrough is that .23.5 now ensures that monopropellent is drained in relation to staging, so I don't need to close the valves on the final stage's tanks to prevent them from being used during the ascent.

I did encounter a small oversight for the next part of the ascent. On the one hand when I cut off the 2nd stage engines for the coasting phase I found that they had run out of fuel at that exact same moment, leaving me on target and ready to engage the third stage orbital/injection engines. However the circulization burn shows that I needed 385 m/s, putting me slightly over budget since some of that should have come out of the 2nd stage. A bigger issue is that I didn't correctly take into account the much lower TWR of the 3rd stage engines. As a result my burn timing is off and the resulting orbit will actually pass as low as 68.9km. On the bright side my course projection to reach the Mun show that I will save over 100 m/s of delta-v over the injection portions budget. I also notice that the display is a little different, I think I must have clicked one of the conic options in PreciseNode. It looks fine, in fact I actually find it more useful this way to visually see my PE without even reading the number so I'll keep it for now. Making the burn confirmed that it makes it easier to visually tell how close my PE was, letting me cut my engines based on sight and get a PE of 13km.

Arriving at the Mun some information is recorded in high orbit before arriving for capture after which a additional experiments can be done in low orbit. A good deal of fuel has been saved so the transit stage will be able to provide some delta-v for the descent. One other thing the transfer stage has provided is electrical power. Prior to starting the landing the batteries in the landing stage need to be activated. They'll provide several more hours of operation without having to carry the weight of the batteries that brought the probe the Mun in the first place. The landing site chosen is a flat looking area in the midlands which should pose little danger.

With the fuel situation good a very soft landing is made at 1.4 m/s. Goo is exposed and the newly acquired Double-C is activated.

With all of the experiments completed the probe lifts off back into Munar orbit. Fuel is plentiful so only battery life is of interest. With PreciseNode installed it makes setting the time parameter of a maneuver much easier (dragging the maneuver node frequently has side effects and is hard to do accurately). The result is a very nicely aligned escape trajectory.

To return to Kerbin after leaving the Mun's SOI a PE of 35km is set with a short burn, however it's thrown off a bit because I didn't reorient the ship before decoupling the unpowered return package. The seperation force pushes the return package PE up to 41km. Instead of returning to Kerbin is 3 hours it takes 10 hours and 5 passes through the atmosphere before it finally loses enough velocity. The automatic parachute engages at 6km for a soft landing.

Recovery of the probes payload provides a healthy increase in science that I have not decided how to spend yet. Should I try to make an early manned Mun landing, or go with a more mundane orbital gravity mapping of the Mun and some exploration of Minmus first and proceed with a Mun landing that would be mostly a copy of my previous playthrough?

[Taleric]

Go for broke and do the early manned mission

Your preparations are so meticulous it will be awesome to see it unfold.

Edited May 18, 2014 by Taleric

[Poddster]

When did you get a grav scan of the poles? How come H-2 didn't do the scan?

edit: Ah, Chandrasekhar 3 did it.

[Dave Kerbin]

Getting ready to go to the Mun and just tidying things up. There are two piles of debris close to Kerbal Space Center, left there by Arend 2 (a pair of solid booster shells) and Baldwin 1 (almost the entire rocket broken into pieces) as shown below on the left during the launch of Eratosthenes 1. I went through each piece of debris from the tracking station and hit the recover button (it's not cheating if I can send a crew to clean it up) to get rid of it. The final piece of debris left on record is the lander from Fleming 1. Since it was out of physics range when the return capsule entered the atmosphere its orbit never degraded (stuck on rails). In comparison with the capsule which was pushed up by the decoupling the lander hardware was pushed down in a 28km PE orbit. Cleaning it up was simply a matter of focusing on it so that it could break up in the atmosphere. I'm now back to a 100% clean solar system.

[Poddster]

Since it was out of physics range when the return capsule entered the atmosphere its orbit never degraded (stuck on rails). In comparison with the capsule which was pushed up by the decoupling the lander hardware was pushed down in a 28km PE orbit. Cleaning it up was simply a matter of focusing on it so that it could break up in the atmosphere. I'm now back to a 100% clean solar system.

You can hit the big red X to save yourself time, if you know it's going to burn up

[Dave Kerbin]

You can hit the big red X to save yourself time, if you know it's going to burn up

I consider the red button a bit of a cheat, it just magically removes stuff. I didn't bother this time around but on previous careers I've edited the setting that disables that button (unfortunately if you do that it also alters how recovery works - you need to actually visit the object to use the recovery button at the top of the screen, and visiting objects after they've landed can sometimes result in kraken attacks).

(From my first career playthrough where I was experimenting with experiment return methods)

[Dave Kerbin]

Manned Mun landing technology

I have a limited budget of 731 science to unlock new items for a manned Mun landing. Here is where I'm starting from.

First I think there are two techs I can't do a landing without. One is Advanced Landing, without this I don't have space suits so my kerbals can't even get out of the ship and look around. The larger landing legs are useful too. The second is Advanced Exploration. I don't think it's practical to try and reach the Mun without the life support of the Mk1-2 capsule. In hindsight it would technically be possible with just Advanced Landing but I'd need to stack at least 4 Mk2 Lander Cans together and that would look stupid. In order to reach Advanced Exploration I need to unlock Electrics first (I can see Advanced Exploration without it, but it's grayed out and Electrics is the only nearby node that might assist in unlocking it). I've spent 450 science leaving me with 281, enough for one more 90 point science item and one more 180 point item.

There are multiple choices here, each one fills in a part of the mission but by taking it I would be leaving out the others. At the very top of the tech tree I could pursue the large diameter fuel tanks and the Keel Haul (prototype Skipper). Next down I could unlock better engines with thrust vectoring. Going further down I have already unlocked the 90pt portion (so I'd still spend 90 on either orange tanks+adapters or T30 engines and small fuel tanks). In the aerodynamics area I could spend 180 to unlock the large heatshield and radial parachutes - I can't realistically land the big Apollo capsule without a heatshield. Or I could spend 180 to get the upgraded batteries.

I don't really have a lot of trouble with the first part of the choice - a heatshield or batteries are much better then the engines or fuel tanks. I can still spend 90 to unlock the T30, which gives me better thrust over the T15. That leaves heatshield or batteries. Initially I was actually leaning toward the batteries, since electricity was my limiting factor in my Mun and Minmus flights. I considered the idea of a direct ascent, single kerbal mission. It would carry a Mk1 escape pod on top for reentry. I loaded up my old save and mocked up what the direct descent lander would look like (I did accidently use a ladder I wouldn't have access to). However while I stayed with direct ascent I decided it was better to go with the heatshield after running some numbers. First was that the mass of the landers was very close - the heatshield weighed less then the Mk1, but the primitive batteries added slightly more weight in return, however in order to use the Mk1 I would need to brake before reentry to lower my speed. That resulted in an extra 7 tons of fuel in the lander.

Mockup of direct ascent lander using Mk1 pod for heatshielded return

So I went with spending science to unlock Super Sonic Flight for the heatshield and Heavy Rocketry for the T30 engine and T200 fuel tank. I also hired on my third kerbal based on the poll results, Barrigh Kerman.

[Dave Kerbin]

Gamow 1 (Part 1)

This is my early Mun shot. I've unlocked the Mk1-2 Capsule to get there, the space suits to explore the surface and the heat shield to return. What I haven't unlocked are the advanced batteries to run the life support system or any of the large diameter fuel tanks or engines. Engine wise I've only unlocked one more, the LV-T30 to replace the LV-T15 and I'm still relying on the experimental LV-420 which is heavier, less efficient and lacks the thrust vectoring of the LV-909. My crew for this mission consists of the 2 kerbals who have already flown into space, Aldrick and Kenby and the last kerbal from the public voting Barrigh Kerman who is the only one who isn't dumb as a post. I need a kerbal like him running the mission since we aren't just throwing them up for a single orbit around the planet.

As I showed before I was already planning this as a direct ascent mission: this is where the lander returns directly to Kerbin instead of docking with a mothership. Even though I had the lander can (since I needed space suits) the direct ascent profile was still important because of the complexity of having both a lander and the mercury style recovery capsule. Once I decided on getting the heatshield instead of batteries I could have changed the profile to a munar rendezvous but I wanted to do it direct ascent simply because I had already done it the other way.

The main mission objectives where simple: Launch from Kerbin, burn to the Mun and capture into low orbit there, perform an orbital survey, land and do an EVA, launch back into orbit and return to Kerbin.

The data I recorded from Fleming 1 proved invaluable in planning this mission. I determined that the smallest reasonable time to reach orbit and begin landing was 6 hours (remember that reasonable means itaking into account less then perfect orbital alignment and burns) and that padding it out to 8 hours would ensure safety. This estimate wasn't that much smaller then my old play through's mission plan. The second estimate was a bit more daring. It told me from Mun descent to final splashdown on Kerbin could be reasonably done in 8 hours, though with an imperfect return 11 or 12 should be budgeted for safety. That gave me a total of 20 hours, again not very different from my first play through, but I intended to use the Fleming profile of carrying some batteries in an injection/capture stage which would be discarded at the beginning of the Mun descent.

The final rocket weighs in at 598 tons, only 10 tons more then my original Uniform 2 mission. And if you compare the designs I think you'll agree that Gamow 1 is much, much more streamlined and realistic in appearance. It also doesn't have a lander sitting on top which makes escape easier in a launch failure (if I had the escape lower unlocked I might have thought to use it, since it would easily integrate into this design). Lift off is smooth but a little slower then usual, I cut it close with the thrust calculations which is why there are those little solid boosters to get it over the top. Those big XL control surfaces combined with the pod SAS keep the first stage flying straight.

At 10.5km the first stage booster is exhausted and discarded. The ship is going about 30 m/s slower then my usual launches as the second stage booster takes over and begins a gravity turn using RCS for control. The SAS system is turned off at this point as it would only waste monopropellent - I'm not so much steering with RCS but using a bit of it to tip the rocket and then let it turn by itself, using RCS to slow down the turn a bit as needed. This seemed to be the scariest portion of the launch judging by the crews reaction.

The second stage runs out at 50km, leaving about 600 m/s for the orbital engines to pickup to reach orbital speed (~2.3km/s). Fortunately they are T30s and where designed to handle this portion of the ascent. A 172 m/s circularization burn is used to complete the setup of a 72km orbit. This orbital section is carrying the only active batteries besides the one in the command pod (which I kept on for safety). All the batteries on the next stage are currently on stand by. Due to symmetry I ended up with more batteries then I needed on this stage, 9.6 hours worth instead of 8, but it wasn't too much of an overage so I kept it instead of splitting things up.

[Dave Kerbin]

I had a question about Gamow 1 over in the BTSM mod thread but I thought it would be better to answer it here rather then derail that discussion.

How do you have this constructed? It looks perfectly symmetrical -- did you have to add most of the engines manually? (In some kind of grouping?)

The ship is built using a combination of the symmetry feature and the cloning feature. You should already how to use symmetry, it's the little button the lower left you can click to get 2x, 3x, 4x, 6x or 8x symmetry when placing a part. Cloning is a feature that a lot of people know about but can be easily overlooked if you haven't read the list of keyboard shortcuts. You clone something by holding down the alt key and clicking on it. You'll now be holding a copy of that part along with all the parts attached to it as if you had just removed it from the parent (but the original is still there!). Below I've created a basic copy of the top of the landing stage of the ship - a Mk1-2 capsule, a heatshield and a decoupler. Below that is a fuel tank and an engine. By alt clicking on the fuel tank I get a copy of the tank and engine. Using 6x symmetry I can place the tank radially, creating 6 symmetrical tanks and engines around the center one.

There is one final 'feature' that I use for this kind of assembly, though it's really more a work around to a minor bug/glitch. Sometimes when you are placing things with symmetry, especially when they are close together like I'll be doing here, you'll find that it rejects some or all of the placements (some or all of the parts show up in red instead of green and you can't place the group). This happens if you have accidently clipped parts together but can also seem to happen for no reason even on parts with no possible clipping issue. The solution is to move the camera a bit and try again. For some really close placements it can get tricky to find just the right angle you need to get it to register but it can be done.

Next we'll create the injection stage. We'll start by building the center tank assembly first using a decoupler, 2 of those long fuel tanks and an engine. Just like before we'll clone it but instead of cloning it from the tank we'll alt+click on that decoupler, cloning the entire assembly including the decoupler. With symmetry mode on we'll then attach the decoupler to the bottom of one of the 6 exposed lander engines - symmetry mode will automatically duplicate it to create 6. Struts can be added at this point to ancher the 6 long tanks so they don't sway around, but I'm not going to cover that part. At each stage assume a single set of struts is used to ancher any long sections together. It doesn't take many, the final rocket has about 1 strut per engine (including the 6 struts used to ancher the command pod at the top).

The injection stage had 7 engines, but the 2nd booster stage is going to need more to lift all that weight. It's going to need 19 engines. That means in addition to the 7 'inner' engines we'll need an outer layer of 12 more. First we construct the inner engines (which are composed of a decoupler, T200 tank, T400 tank, T800 tank and LV-T30 engine) the same way we did with the injection stage. Next we clone the engine assembly but without including the decoupler. Much like when we constructed the lander portion we attach it radially. You'll notice that you only have two symmetry options when touching the tank - 1x or 6x. The VAB won't let you use any of the others because you are attaching to/extending an existing symmetrical group (there are some tricks for assembly with multiple layers of differing symmetry but that's for another day). You can experiment with the exact angle to attach them in combination with the next step. You'll want to be just off the straight on attachment angle in order to make the next set of tanks you add appear seamless.

Now we can start creating some fake 12x symmetry. Clone the tank again and attach it to your outer most tank, but instead of extending them out again you'll do the opposite, try to place them as close in as possible without clipping (if it turns red you are clipping and can't place). Look closely and you'll see the small T200 tank I'm attaching the assembly to, it's highlighted one on the left. In this arrangement the tank is technically attached to the one to its left, but the gap between it and the tank to the right is small enough that they appear equally space for all but the closest inspection. If the gap is big then go back to the previous step and adjust the attachment angle. You can now add some nose cones. You'll notice that they only attach to 6 tanks at a time, this is because you're really still using 6x symmetry, but wrapping it around to fake 12x.

For the bottom of the rocket, the first stage booster, we'll need 37 engines in total. The first 19 are placed the way we placed the first 7 engines of the previous stage. We start with the very center and build a single assembly consisting of a decoupler, T400, T800 and LV-T45 engine. Now clone that at the decoupler and attach it to the bottom of the other engines with symmetry on. Each placement will automatically be copied to 5 other engines so you'll need to place it 3 times to get all 18. At this stage you will probably start encountering those placement issues so rotate the camera a bit if it doesn't recognize all 6 as valid.

To form the outer most layer we'll need 18 engines. That means for each of the existing 12 outside engines we'll need to attach 1.5 more. Clone an assembly, minus the decoupler, and place it sticking straight out from one of the existing ones. You've extended 6 of the 12 existing engines, leaving 6 with nothing attached radially. Pan the camera around to focus on one of those assemblies with nothing attached.

You're going to clone and attach 2 assemblies to this engine, one angled toward the left neighbor and one to the right. If you do it correctly it the distance between all the tanks should appear equal, creating fake 18x symmetry. One thing that will take a little practice at all stages is getting the height lined up (in the example I've been assembling for these screenshots I've been moving quickly so there is a small amount of vertical misalignment). Once assembled you can add nose cones and you're almost done.

Remember that this isn't true 18x symmetry, it's 6x symmetry with three pieces. So when it comes to attaching the fins we don't have to worry about any manual attachment, we can just attach them to a single grouping of 6. The little boosters are added last and again you will need to pay a little attention to make sure you vertically line them up.

And now you have a completed ship*

*Batteries, landing gear, RCS and parachutes extra.

[Jacke]

It's big, isn't it?

I've done similar builds, Dave, but never to that scale.

One thing I do if I figure I know what I want is I build the whole centre string first, from top stage to bottom stage. Then I clone and symmetry it where there are added full length ones, then I clone off of lower spots to add the shorter strings of tanks, engines, and decouplers. I haven't had a problem with mine.

Another that helps is a BTSM unapproved mod, EditorExtensions, specifically its vertical snap, which uses a feature in the editor that isn't normally accessible but is part of stock. Toggle that on and off with 'v' and it really helps to get added parts vertically alligned to similar components. (It also has a very naughty debug clipping toggle, but I don't use that as it's just asking for rockets to break.)

[Dave Kerbin]

It's big, isn't it?

Well it weighs just a tad short of 600 tons on the launchpad. I would actually be interested in knowing how heavy other BTSM player's manned Mun spaceships are. The only other reference I really have is my own previous ship (almost the same weight) and a work in progress by Ninjatsu that I can estimate is around 1000 tons.

You can find the weight of your entire ship by starting it up on the launchpad but instead of launching press M to go to the map and then over on the right click on the button labeled (i). It will expand and show information about your ship, including the total mass and the number of parts. If you are playing BTSM and have sent kerbals to the Mun please post a screenshot showing off your ship and its launchpad mass.

[LannyRipple]

I would actually be interested in knowing how heavy other BTSM player's manned Mun spaceships are.

Launchpad weight is 482.1 tons with 122 parts. LKO lifter is 67 parts and will put 43 tons into LKO with 400-500 dV remaining in last stage. I could redesign the second stage so it wasn't such overkill but so easy to just grab the assembly and apply.

My Minimus manned uses the same lower 3 stages but has a launchpad weight of 498.4 tons with 182 parts (yay! Panels!! :/ 59.2 tons into LKO with lower three stages consumed.

Both Mun and Mini use an Apollo style lander so 2 Kerbals sent on each mission. I have T7 filled in and the cupola node in T8. (Which means I need to redesign landers for the Biometric Sensor Array.)

PS - Just played around a bit with T5 + 3x T6 (lv909, heat-shield, landing legs). I missed getting home by 70-100 dV but got a full landing with Jeb, Bill, and Bob and back into orbit only failing to get all the way out of Munar orbit for a transit home. Launchpad weight was 472.1 tons with a part count of 168.

PPS - I use MechJeb for weights, deltaV, and TWR.

Edited May 21, 2014 by LannyRipple

[HeadHunter67]

Thanks for all the useful advice lately, Dave. I just finished my first Mün landing in BTSM - the rocket was almost identical to your Fleming mission. After a couple design hiccups, I made it there safely (I did have to load about twice as much monopropellant and a small reaction wheel, I'm not that good a pilot!)

Coming back was the challenge - a little trial-and-error to get the right Pe upon separation, and then realizing I needed to adjust the default parachute settings or it would burn up! Thank the Maker for Alt-F5. Eventually I splashed down safely for 652 Science. I chose to unlock Advanced Electrics in addition to the three required nodes for a good manned mission. I'm about 30 shy of another T5 node, but you were right about the payout!

If it weren't for your mission reports, I'd probably have been overcome with frustration by now. I get a lot of enjoyment out of reading your reports, and more out of knowing that the next step is possible and taking some tips on how to do it!

[Brucey]

Well it weighs just a tad short of 600 tons on the launchpad. I would actually be interested in knowing how heavy other BTSM player's manned Mun spaceships are.

I just posted about my manned mun experience on the BTSM thread. Using 3 separate missions to get kerbals to the mun and back.

Mission 1: 1263 tons, 174 parts

Mission 2: 1145 tons, 178 parts

Mission 3: 1165 tons, 162 parts

I think the reason I'm so much heavier is I use all Rockomax parts. Much bigger, fewer parts, but also much less efficient.

Edited May 21, 2014 by Brucey

[Jacke]

Well it weighs just a tad short of 600 tons on the launchpad. I would actually be interested in knowing how heavy other BTSM player's manned Mun spaceships are. The only other reference I really have is my own previous ship (almost the same weight) and a work in progress by Ninjatsu that I can estimate is around 1000 tons.

You can find the weight of your entire ship by starting it up on the launchpad but instead of launching press M to go to the map and then over on the right click on the button labeled (i). It will expand and show information about your ship, including the total mass and the number of parts. If you are playing BTSM and have sent kerbals to the Mun please post a screenshot showing off your ship and its launchpad mass.

http://i.imgur.com/ZGS6zDH.png

Or if you use one of the 3 engineering mods (I use all 3, Kerbal Engineer Redux, MechJeb2, and VOID), you can see the data in the VAB.

Back in KSP v0.23, I launched a unmanned version of my direct ascent Mk1-2 command pod design that was 579 tons, made with the 2.5m Rockomax parts. Had many design flaws, including ineffective strutting (especially for v0.23), a weak 2nd stage, and a overly busy landing profile that included dropping the 3rd mission stage just before landing. But the wrong placement of the landing legs--too high--had the engine hit the ground on touch down, breaking it off and stranding it and its Goo payload.

After much wailing and knashing of teeth, I developed a better design and learned a lot about v0.23 strutting. It never flew (decided to restart the campaign after v0.23.5 was released) but had a launch weight of 654 tons.

[LannyRipple]

I just posted about my manned mun experience on the BTSM thread. Using 3 separate missions to get kerbals to the mun and back.

Mission 1: 1263 tons, 174 parts

Mission 2: 1145 tons, 178 parts

Mission 3: 1165 tons, 162 parts

I think the reason I'm so much heavier is I use all Rockomax parts. Much bigger, fewer parts, but also much less efficient.

Your extra weight is all the fuel you are using. You could get by with a smaller setup. I noticed you mentioned you haven't done any research so without knowing your stage deltaV or TWR it gets a lot trickier (coming down to luck and experience from what you've tried before).

Dave -- You should probably also ask folks if they use design tools like KER (or by hand) or just eyeball it. You are going to get radically different values for the two approaches.

[Dave Kerbin]

Dave -- You should probably also ask folks if they use design tools like KER (or by hand) or just eyeball it. You are going to get radically different values for the two approaches.

KER isn't the only way to design efficient rockets, it can be done by hand too. In fact I'd argue it may be easier to do with an Excel spreadsheet since you can directly manipulate the numbers and even use reverse functions to immediately find the optimum values instead of just going by trial and error in the VAB to see what numbers KER displays for each combination of parts. My rockets for BTSM aren't exactly small, but that's because I find that BTSM has other goals to reach for like safety margins and even just getting there. In stock where the risks are low I can be much more aggressive. For example my .23 career in the signature, or for combining looks and light weight my Duna ship.