Lifters, light, non-heavy, mainly-SRB and pancake, a method

[AstroDoc]

I'm playing version 0.90. Early on in the career game, before the science tree gets fully opened up, the contracts called for a range of lifters for orbit and Mun and Minmus missions. I'd patched together lifters in the past but I wanted a more organised approach. Having created a payload I wanted to easily find a pre-tested lifter, with only partly-opened-science-tree parts, to get it up.

I am aware that advanced players use 'delta V' to calculate things, and I could probably learn how to do that, but I do sometimes like to try doing things my own way. I did come across some formulae for calculating delta V, a complex one for multi-stage rockets and a simpler one for single-stage craft, both on this forum (on one of the threads with 'lifter' in the title). Kerbals seem like simple folk though, so I wanted something easily understandable. On reflection, my calculations end up being about acceleration and time, and velocity does equal acceleration by time.

Before starting this project, I did search all forum threads with 'lifter' in the title, ignoring the ones for 'heavy' lifters.

Some observations I'd made underpinned my approach :-

* Drag seemed to be a problem at 100m/s at 1000m, at 250m/s at 5000m, and much less of an issue above 10000m (these particularly noticed while using space planes)

* The faster the take-off (taking into consideration the drag) the more efficient the lifter

* Engines used at 100% power seemed more efficient than those with lower thrust settings

* Solid rocket boosters (SRBs) seemed significantly cheaper than liquid fuel engines (LFEs)

* Almost all of my rockets had a payload which included a LFE at the base, so I wanted a lifter to 'nearly' get me where I wanted to go, then the payload could do the last bit

* There's an unexpected slow-down after dropping off a stage .. and after calculating/trialling some lifters, I found 3 stage lifters were more cost-efficient than 4 stage lifters

* After calculating/trialling some lifters, the 315 strength SRB wasn't all that useful compared with the 250 and the 650 SRBs

Using trial and error I found the payload that the different lifting engines could lift, which would get the rocket to 100m/s at 1200-1300m. I measured how long each engine lasted at sea level (ASL) and above 10000m eg the 250 SRB can lift it's own mass (3.75t) plus payload 10.35t [Total 14.1t] at the required acceleration, and goes for 29 secs ASL and 31 sec above 10000m

Using those findings plus trial and error, I found the required time a 3-stage lifter needed to get the payload nearly to 'orbit' (~186 sec total lifter work + or - ~3sec), 'Mun influence' (~214 sec), and 'Minmus influence' (~216 sec). Leaving Kerbin influence required very little added thrust compared with getting nearly to Minmus influence.

Creating lifters, I made sure each stage could lift itself and the mass above it at the required acceleration (or 'close to', or better).

Getting to Mun and Minmus influence I used the 'aim straight up, 45 degrees ahead of the Mun (or Minmus)' strategy.

I created a spreadsheet, which grew as much by evolution as design, to do most of the calculations. I allowed for reduced fuel levels in a stage to reduce weight/mass. The spreadsheet would provide the percentage power level required for each stage

I found I could predict the type of lifter and power levels required to get a certain mass up, with reasonable accuracy. I calculated the maximum mass each lifter could get up, then tested it. I noted the fuel required by the payload LFE to finally get the payload to the desired place eg to the altitude needed to get within Mun influence (if that was the target). I calculated cost per ton for each lifter to get the mass to orbit, for comparison. To get an in-between mass up, I could reduce the fuel in the 3rd stage (just prior to payload), and make a prediction using the evolving spreadsheet. I compared some of my patched-together lifters with spreadsheet-designed ones, and the designed ones did better. I created some lifters using the spreadsheet (lifters I'd not created before) which was useful. I found I could 'get a bit more' by setting the 3rd stage to 100% power for orbit (not with the very low payload rockets), and the 2nd and 3rd stages to 100% for Mun/Minmus, and by setting the power a few percent higher (usually ~5% higher) for the 1st stage.

Note that the tested payloads had only an OKTO as the pod and no added 'control' components

Note that the mass information near the bottom right corner in the rocket-building screen was very helpful.

Note that my strategy to to get to orbit involves angling the rocket to ~22 degrees by around 10000m up, 45 degrees by around 22000m, quickly starting the move to get to 90 degrees when the 'apo' gets to ~52000m, and (except for the smaller rockets) delaying the firing of the 3rd stage until quite late (call it the '5 step takeoff').

I found that for '4S' 1st stage rockets and larger ones, starting the angling around 2-3000m and doing it more gradually, and having a no-thrust break between stages, got a greater mass into orbit

Despite the feeling that overlapping stages in Mun/Minmus lifters seemed to help, with few exceptions the final results were better by just doing the stages one straight after the next (firing the next while releasing the one before).

Note that my Sepratrons tend to be tweaked to 60% power and 50% fuel for the 650 SRBs (or pairs or triplets of them)

** SPOILER ALERT ** If you enjoy making your own lifters, and working things out for yourself, don't look at my results (below) too closely

1st stage (power percent) [fuel percent], 2nd stage () [], 3rd stage () [] - Target - Payload mass (payload fuel needed to get to target) [Lifter cost, cost per ton]

NB S = SRB. L = Mainsail. Power and fuel percent only included if not 100% (with a few exceptions). '$' used for Kerbal currency for convenience

(1 S 250, 1 S 250 .. 1 S 250, 1 S 250, 1 S 250 .. 1 S 315, 1 S 250, 1 S 250 .. On my list but not included here .. Much payload fuel used to get to goal with these)

1 S 650 (89), 1 S 250 (70), 1 S 250 (43) - Kerbin orbit - 2.3t (2 fuel units) [$4850, $2110/t]

1 S 650 (90), 1 S 250, 1 S 250 - Minmus influence - 1.2t (0.64 fuel units - back towards Kerbin)

2 S 650 (77), 1 S 250 (78), 1 S 250 (51) - Kerbin orbit - 3.3t (4f) [$8000, $2425/t]

2 S 650 (80), 1 S 250, 1 S 250 - Minmus influence - 1.8t (0.15f)

2 S 650 (100) [90], 1 S 650 (88), 1 S 250 - Kerbin orbit - 5.6t (10f) [$9000, $1610/t]

2 S 650 (94.5) [90], 1 S 650, 1 S 250 - Mun influence - 3.1t (0f)

2 S 650, 1 S 650, 1 S 250 - Minmus influence - 3.1t (2f - back towards Kerbin)

3 S 650 (93), 1 S 650, 1 S 250 - Kerbin orbit - 7.7t (4f) [$12200, $1585/t]

3 S 650 (94.5), 1 S 650, 1 S 250 - Mun influence - 4.1t (2f)

3 S 650 (89), 1 S 650, 1 S 250 - Minmus influence - 3.9t (0f) NB 3 extra struts needed to make the lifter work

NB 3 S 650, 1 S 650, 1 S 315 eg 4 t to Mun Inf with 4 f needed - Not as good as 3S 1S 1s

NB 3 S 650, 1 S 650, 3 S 250 eg 4.2 t to Mun Inf with 3 f needed - Not significantly better than 3S 1S 1s

NB 3 S 650, 1 S 650, 1 S 250, 1 S 250 eg 4.3 to Mun Inf with 1 bf needed - Not significantly better than 3S 1S 1s

4 S 650 (85), 1 S 650, 1 S 250 - Kerbin orbit - 9.3t (0f) [$13400, $1440/t] NB 8.7t (3f) with '5 step takeoff'

4 S 650 (90), 1 S 650, 1 S 250 - Mun influence - 4.8t (0f)

4 S 650 (90), 1 S 650, 1 S 250 - Minmus influence - 4.6t (1f)

5 S 650 (87), 1 S 650, 1 S 250 - Kerbin orbit - 9.7t (0f) [$14000, $1445/t]

5 S 650 (86), 1 S 650, 1 S 250 - Mun influence - 5.6t (3f)

5 S 650 (86), 1 S 650, 1 S 250 - Minmus influence - 5.4t (4f)

6 S 650 (85), 1 S 650, 1 S 250 - Kerbin orbit - 10.9t (0f) [$18000, $1650/t]

6 S 650 (82), 1 S 650, 1 S 250 - Mun influence - 6.2t (1f)

6 S 650 (82), 1 S 650, 1 S 250 - Minmus influence - 6.0t (4f)

6 S 650 (94.5), 6 S 250, 1 S 650 - Kerbin orbit - 13.9 (12f) [$21700, $1560/t]

6 S 650 (94.5), 6 S 250, 1 S 650 - Mun influence - 7.5t (7f)

6 S 650 (94.5), 6 S 250, 1 S 650 - Minmus influence - 7.2 (8f)

NB There was a benefit with this one for starting 3rd stage engines while 2nd stage engines were still firing, for the Mun/Minmus lifters

6 S 650, 3 S 650, 1 S 650 - Kerbin orbit - 18.7t (2f) [$25500, $1365/t]

6 S 650, 3 S 650, 1 S 650 - Mun influence - 10.2t (3f)

6 S 650, 3 S 650, 1 S 650 - Minmus influence - 9.8t (5f)

9 S 650, 3 S 650, 1 L [with 1080 fuel] - Kerbin orbit - 24t (34f left over) [$43700 ($1820/t)]

9 S 650, 3 S 650, 1 S 650 - Mun influence - 12.8t (7f)

9 S 650, 3 S 650, 1 S 650 - Minmus influence - 12.2t (5f)

8 S 650, 4 S 650, 1 L [with 1440 fuel] - Kerbin orbit - 27.5t (14f left over) [$48150 ($1750/t)]

8 S 650, 4 S 650, 1 L [with 1440 fuel] - Mun influence - 15t (11f)

8 S 650, 4 S 650, 1 L [with 1440 fuel] - Minmus influence - 14.5t (7f)

12 S 650, 4 S 650, 1 L [with 1440 fuel] - Kerbin orbit - 35t (14f left over) [$55800 ($1595/t)]

12 S 650, 4 S 650, 1 L [with 1440 fuel] - Mun influence - 18.5t (11f)

12 S 650, 4 S 650, 1 L [with 1440 fuel] - Minmus influence - 17.5t (5f)

NB 8 S 650, 4 S 650, 1 L [with 2880 fuel] - Kerbin orbit 35t (18f left over) [$54650 ($1560/t)]

Not as nicely 'designed' but a bit cheaper than the nicely 'designed' 12S lifter above

NB 16 S 650, 8 S 650, 1 L [with 1440 fuel or 1800 fuel] both made obsolete by 2-stage lifters

Somewhere after 35 t, with one exception below, 2 stage lifters with an overworked Mainsail tend to be cheaper

Need care with struts etc, because sometimes the larger lifters can wobble and come apart just after lift-off

12 S 650 (76), 1 L [with 5760 fuel] - Kerbin orbit - 39t (172f left over) [$60500 (~$1550/t)]

12 S 650 (76), 1 L [with 5760 fuel] - Mun influence - 22.1t (4f)

12 S 650 (76), 1 L [with 5760 fuel] - Minmus influence - 21t (3f back towards Kerbin)

16 S 650, 1 L [with 5760 fuel] - Didn't get to test due to glitch (1-2 Mainsail fuel tanks just disappear on staging)

24 S 650, 1 L [with 5760 fuel] - Didn't get to test due to glitch

18 S 650 (70), 1 L [with 5760 fuel] - Kerbin orbit - 52t (180f left over) [$73750 ($~1420/t)]

18 S 650 (70), 1 L [with 5760 fuel] - Mun influence - 28t (6f back towards Kerbin)

18 S 650 (70), 1 L [with 5760 fuel] - Mun influence - 29t (12f)

18 S 650 (70), 1 L [with 5760 fuel] - Minmus influence - 27.3t (14f)

16 S 650, 8 S 650, 1 L [with 2880 fuel] - Kerbin orbit - 60t (80f left over) [$82700 (~$1380/t)]

16 S 650, 8 S 650, 1 L [with 2880 fuel] - Mun influence - 34t (5f back towards Kerbin)

16 S 650, 8 S 650, 1 L [with 2880 fuel] - Minmus influence - 33t (11f)

NB This lift wasn't 'designed' for an orbit mission, but ..

Some screenshots included below showing how I tended to assemble these lifters, plus there's an image of one of my spreadsheets

[see my own reply **5 replies down** with some LFE-final-stage lifters. Cheaper than these, but requiring player time to recover the final stage to make them cheaper]

I would appreciate comments, particularly from others who have tried to find a 'method' (or found a simpler one), and from anyone who can get similar masses into space significantly cheaper than those listed above. I will cope with being called 'utilitarian' (already labelled as such on another thread .. or something equivalent) because none of these lifters have any 'style' or 'flair' to them. I presume there might be the people out there who would find this approach/list interesting or helpful.

Edited July 15, 2015 by AstroDoc

[Taki117]

Good Gravy that's a giant wall of text. In other news you are seriously complicating things for yourself. While trial and error is good, you really need to calculate dV either using a mod like Kerbal Engineer or by doing it by hand. Also, how are you getting to Mun/Minmus? If you are trying to launch straight there (And simply getting the requisite altitude) that is horribly inefficient, and you should instead get to orbit, and then use a liquid fueled stage to get to the other bodies. Something else to consider, is that for a larger payload, more power is required so you might consider using liquid fueled boosters in your heavier lift designs, as well as adding winglets to your heavier lifters for control, instead of lots of SAS, (Which is more expensive than a set of 4 winglets which should give you plenty of control authority)

[Acet]

Interesting look into it. As the previous poster pointed out, you seem to not be using something like Kerbal Engineer or MechJeb to get dV values calculated directly for each setup, which probably explains why it feels that you started your analysis from a lower base of understanding.

A couple of points which dovetail with what you have observed:

- The balance point between losses due to staying too long in the gravity well and going up too fast (thus loosing too much energy to drag) is called the terminal velocity. As you have noticed, in Kerbin it's around 100m/s at 2000m, 120m/s at 8000m and then onwards it quickly goes up to the point that it's not worth trying to reach it. One of the ways one can squeeze extra mileage of a build is to tune it so that climb speed is roughly the same as terminal speed.

- Don't forget that another way of saving on costs is making recoverable stages. Thus for example my mid-sized launcher with a payload of about 25 tons has a liquid fuel central core (Skipper engine + orange tank) and a ring of 8 boosters, and actually costs about 10k less than yours, simply because that central core is recoverable (it has a probe core, parachutes and a bit of reserve fuel for deorbittng) which gives me 33k back.

- One of the reasons for wanting to have a liquid fuel component in a launcher is thrust control. The extra thrust from the liquid fuel engine can be used in the first 2000m to reach terminal velocity as fast as possible, then be switched off while the boosters propel you through the thicker atmosphere, and later switched back on above around the 10000m mark when both terminal velocity is much higher and the effective ISP of that engine is now much higher since it's closer to vacuum ISP. Also, when Apoapsis reaches the desired orbit hight, it's nice to be able to control thrust - your little scheme of "onwards and upwards" to reach the Mun and Minmus is much harder to make work when you're trying to find the correct heading and speed for a fuel efficient Jool transfer.

[Rokmonkey]

Good grief that is a lot of SRB's

So, delta-V, if you really want to make efficient rockets, you need to learn it. It's critical. Simply put, delta-V is a measure of how much fuel you have. It's measured in velocity, seeing as how in space all of your maneuvers are just changes in velocity at different times. There are many guides out there that can tell you how to do that by hand, it is a very simple, if tedious, calculation. Or you can get Kerbal Engineer or MechJeb to show you the dV of each stage of your rocket in the VAB.

To address some of your observations, I'm assuming you are running stock aero, and not FAR or NEAR.

With Kerbins atmosphere, you want to keep your speed below 200m/s when you are below 10km. That's roughly where your terminal velocity is so anything more than that and your are wasting precious fuel fighting atmospheric drag.

Too high of a TWR and you quickly straight breaking the rule of thumb of keeping your speed low int he lower atmosphere.

Yes, if you have designed your rocket to have an optimal TWR at full thrust, you will be better off than one where you need to reduce throttle to get the optimal TWR. You are carrying too much fuel, and wasting a lot of fuel trying to get it up into orbit.

SRB's are definitely cheaper, for a reason. They have no throttle, no control, and you can't turn them off. they are RARELY, and I mean RARELY used beyond your first stage. They are a great way to kick your rocket off the ground but carrying them along for the ascent is wasteful. You are carrying dead weight. Unless you optimize everything, using math and tweakables to your advantage you are going to waste funds trying an all SRB rocket to the Mun.

Efficient designs utilize liquid fueled boosters for nearly all of the mission, not just the payload, ascent and all.

The "strength" of the SRBs are dependent on how you use them. It's very hard to state categorically that one is better than the other. Especially given as to how you can tweak the thrust and fuel in them to get almost exactly what you want.

Now, I see you are being very particular about your trials and record keeping. One thing to keep in mind, "flight time" is not the only variable you should be watching. You want to look at the velocity as well. If you want to get a really good handle on it, mark the velocity prior to activating the stage, then mark the velocity after as well as the time of the burn. This is actually your delta-V for that stage. (Velocity after - Velocity before)/Time of Burn

I hope that helps a little.

[Pecan]

You're limited in part-count as well as mass for launch in Career mode so these are prohibitively complicated for most people. Apart from cost, what are you considering as your measure of 'efficiency'? If it's payload-ratio (the percentage of launch-mass that is the final payload) you don't seem to list it. If you're just interested in cost then you should consider recover value - those SRBs don't have any.

Regarding:

Some observations I'd made underpinned my approach :-

* Drag seemed to be a problem at 100m/s at 1000m, at 250m/s at 5000m, and much less of an issue above 10000m (these particularly noticed while using space planes)

* The faster the take-off (taking into consideration the drag) the more efficient the lifter

* Engines used at 100% power seemed more efficient than those with lower thrust settings

* Solid rocket boosters (SRBs) seemed significantly cheaper than liquid fuel engines (LFEs)

* Almost all of my rockets had a payload which included a LFE at the base, so I wanted a lifter to 'nearly' get me where I wanted to go, then the payload could do the last bit

* There's an unexpected slow-down after dropping off a stage .. and after calculating/trialling some lifters, I found 3 stage lifters were more cost-efficient than 4 stage lifters

* After calculating/trialling some lifters, the 315 strength SRB wasn't all that useful compared with the 250 and the 650 SRBs

Terminal Velocity - your 'drag' problem - values are listed on the Kerbin page of the wiki.

TWR for each stage determines how fast the vehicle will accelerate and faster is not always better. In particular a launch TWR of 1.6 or so is usually best in stock, as low as 1.2 using FAR. In general, the average TWR over the life of a stage should be just over 2 to reach and maintain terminal velocity.

Using liquid-fuelled engines at less than 100% thrust means you're carrying more engine mass than you need so, yes, use at 100% or replace with lighter ones. SRBs, on the other hand, can't be throttled and should be tweaked in the VAB to adjust the TWR for their stage. In any case SRBs are heavy for their total thrust and should only ever be used in a first stage, if at all.

After dropping a stage the mass is reduced but you're also reducing the thrust available so you should expect to accelerate slower if the overal TWR decreases. On no account should you actually be slowing down, as that means the stage is completely underpowered.

Throwing things at the sky is fine if you like that sort of thing, but to quote Apocalypse Now (which is likely to happen with these 'designs'), "I don't see any method at all, sir".

I suggest you read a little about deltaV, TWR, terminal velocity and staging strategies, as well as something about rocket design - you might like my 'Exploring' tutorial, which starts with payloads under 1t.

[AstroDoc]

Thanks. I am grateful for your comments. I am pleased with the 'view' count so far.

On reflection, perhaps I should have added 'cheap and disposable and time-saving' into the title.

At the beginning of the project I had meant to stop at the 9 S 650, 3 S 650, 1 S 650 lifter, but I got 'carried away'.

Yes, it was a 'giant wall of text'. As a doctor who regularly reads research papers, I am used to having to read a lot of text on background, method, and results. It seemed only natural to include everything.

Yes, I must soon move on to using delta-V calculators to assist me in creating rockets.

For Mun and Minmus, I agree the delta-V difference in making an orbit then expanding that orbit out, versus aiming straight up, can be significant eg for my 15 t Mun payload, going straight up, I need to expend 72 payload fuel units to create the same Mun-direction orbit with one end at Mun altitude, that I can get by using the same rocket and orbiting Kerbin first (and expending no payload fuel). This would be less for different-direction orbits required by some of the Mun contracts. Going straight up takes less player time, which has it's merits when there are dozens of contracts ahead. For other planets I aim straight up for Kerbin escape (aiming backwards along the line of Kerbin orbit for Eve etc and forwards for Jool etc) then once in Kerbol orbit I expand or contract orbits to create a transfer orbit.

The winglet idea is a good one, particularly for the 8 S 650, 4 S 650, 1 S 650 and 12 S 650, 4 S 650, 1 S 650 lifters

I hadn't looked up the figures for terminal velocity, and I appreciate that 'Acet' provided them.

I trialled parachutes etc on the LFE stage of one of my lifters above, and I can recover significant costs that way. There is significant player time required for that added step.

I am only using stock parts. I agree there is a lack of efficiency. Interestingly, when I tried the '8S 1L(Skipper) [2880] 25t' lifter below, slowing the SRBs down to minimise encroachment on terminal velocity under 10000m, and using some LFE thrust for a few secs at the beginning, it didn't get to orbit. 'Throwing it at the sky', giving the SRBs 85% thrust, the lifter worked. Perhaps terminal velocity is more important for bigger rockets with more drag.

Having tried 2-stage lifter with an overworked Mainsail (overworked from my project's point of view), I should have thought to try the same idea on Skippers and the LV-T30

Unfortunately some of the new lifters below were tested with the LV-T45

In response to replies I add some new lifters

1st stage (power percent) [fuel percent], 2nd stage () [], 3rd stage () [] - Target - Payload mass (payload fuel needed to get to target) [Lifter cost, cost per ton]

NB S = SRB S 250 = RT-10, S 650 = S1 SRB-KD25k. Power and fuel percent only included if not 100% (with a few exceptions). '$' used for Kerbal currency for convenience

6 S 250 (46), 1 LV-T45 - Kerbin orbit - 2.8t (34 f left over) [$13300 - ~$7000 = ~$6300 (No signif saving, but might fill a niche)]

2 S 650 (90), 1 LV-T45 [with 900 fuel] - Kerbin orbit - 5t - (76f left over) [$13800 - ~$6600 = ~$7200 (save ~$1800)]

2 S 650 (90), 1 LV-T30 [with 900 fuel] - Kerbin orbit - 5t - (88f left over) [$13700 - ~$6500 = ~$7200 (save ~$1800)] ** LV-T30 **

3 S 650 (82), 1 LV-T45 [with 900 fuel] - Kerbin orbit - 7t - (67f left over) [$16350 - ~$6600 = ~$9750 (save ~$750 .. and might fill a niche)]

4 S 650 (80), 1 LV-T45 [with 900 fuel] - Kerbin orbit - 9t - (44f left over) [$17500 - ~$6600 = ~$11000 (save ~$2400 .. and cheaper than S 650 just below)]

2 S 650, 1 Skipper [with 2880 fuel] - Kerbin orbit - 9t (140f left over) [$26650 - ~$17450 recovered cost = ~$9200 (save ~$4200)]

2 S 650, 1 Skipper [with 2880 fuel] - Kerbin orbit - 11t (54f left over) [$26650 - ~$17450 recovered cost = ~$9200 (save ~$8800)]

3 S 650, 1 Skipper [with 2880 fuel] - Kerbin orbit - 12t (155f left over) [$29440 - ~$17440 recovered cost = ~$12000 (save ~$6000)]

3 S 650, 1 Skipper [with 2880 fuel] - Kerbin orbit - 14t (40f left over) [$29440 - ~$17440 recovered cost = ~$12000 (save ~$9700)]

4 S 650, 1 Skipper [with 2880 fuel] - Kerbin orbit - 15t (124 f left over) [$30450 - ~$17550 recovered cost = ~$13000 (save $8700)]

4 S 650, 1 Skipper [with 2880 fuel] - Kerbin orbit - 16t (70 f left over)

6 S 650 (90), 1 Skipper [with 2880 fuel] - Kerbin orbit - 20t (90f left over) [$35200 - ~$17200 recovered cost = ~$18000 (save ~$7500)]

8 S 650 (85), 1 Skipper [with 2880 fuel] - Kerbin orbit - 25t (31f left over) [ $39800 - ~$17300 recovered cost = ~$22500 (save ~$9000)]

8 S 650, 1Mainsail [with 5760 fuel] - Kerbin orbit - 30t (314f left over) [$58200 - ~32200 recovered cost = ~$26000 (save >$22000)]

8 S 650, 1 Mainsail [with 5760 fuel] - Kerbin orbit - 34t (26f left over) [$58200 - ~32200 recovered cost = ~$26000 (save >$28000)]

Again some pics below

Edited February 28, 2015 by AstroDoc

[AstroDoc]

A lot of my initial Kerbin orbits with LFE-last-stage-before-payload rockets tend to be ~72000m and largely circular. For recovering the last stage I suggest :-

In 72000 orbit, moving over Kerbin on the opposite side of the planet to ksp site, shrink the orbit and bring in 'peri' near ksp site to ~48000. Have the 48000 'peri' sitting over a spot on the ocean which is directly under the far end of the right-angled 'bay', 2nd bay up along the coast from the ksp site.

I splash down in the ocean not too far out from ksp site

[Pecan]

My main problems with this are just being able to read it.

I'm still not sure what the objective is - are these meant to be particularly cheap? If so, shout it!

Part names, for instance. What you refer to as "The 250 SRB" is an RT-10. Part names and (SRB) burn times are listed on the wiki: http://wiki.kerbalspaceprogram.com/wiki/Parts

The spreadsheet in the OP tells me nothing.

I can't tell how lines like "5 S 650 (87), 1 S 650, 1 S 250 - Kerbin orbit - 9.7t (0f) [$14000, $1445/t]" relate to the pictures, if at all.

Apart from that. A suggestion - you can probably save some mass and cost by attaching SRBs in the same stage directly to each other, instead of using the girders. I haven't had any overheat yet.

A possibility - you seem to have a lot of parachutes arranged to land the returning stage on its side. I've had better luck with just a couple of 'chutes and landing on the engine, using residual fuel for a suicide burn.

And a question - roughly what recovery percentage are you working on? (It should be shown in the recovery window).

[breakthrough]

This may get nerfed in 1.0 but the adapter pieces that hold fuel (such as the C7 brand adapter and the Mk3 to 3.75m) are so much cheaper than regular fuel tanks that you can beat SRB costs with liquid fueled engines. Doubly true if you keep all the engines on the core and recover them all.

[Dewirix]

A possibility - you seem to have a lot of parachutes arranged to land the returning stage on its side. I've had better luck with just a couple of 'chutes and landing on the engine, using residual fuel for a suicide burn.

I've just switched to a similar system. The advantage of just taking up a couple of parachutes is that you're not lugging as much mass all the way up to orbit and back.

In terms of cheap launch vehicles, have you looked into single-stage-to-orbit designs? The advantage these have over disposable SRBs is that nothing is thrown away, so you can recover 90-100% of the non-fuel/payload costs of a launch.

In my current career save I've got a workable design that can achieve orbit with around 1200l of liquid fuel and 1450l of oxidiser (shown below on the right of the image).

[Pecan]

I've just switched to a similar system. The advantage of just taking up a couple of parachutes is that you're not lugging as much mass all the way up to orbit and back.

In terms of cheap launch vehicles, have you looked into single-stage-to-orbit designs? The advantage these have over disposable SRBs is that nothing is thrown away, so you can recover 90-100% of the non-fuel/payload costs of a launch.

In my current career save I've got a workable design that can achieve orbit with around 1200l of liquid fuel and 1450l of oxidiser (shown below on the right of the image).

http://cloud-4.steamusercontent.com/ugc/29608660499294878/2E03DDAADECFB0409F0ED5127783F0B24607B8B1/1024x640.resizedimage

Chapter 7, Section 4 of 'Exploring The System' (link in signature) illustrates a 40t-payload SSTO rocket that I often use. Section 5, a pasenger SSTO spaceplane (there are others in earlier chapters).

Although I don't illustrate a vertical-launch wingless jet SSTO as in your illustration they are the most cost-efficient if you can land them close enough to KSC. My designs use turbojets all the way to space (tiny rockets for tiny circularisation burn) rather than basic jets and a heavy rocket engine though. I air-hog, typically 8 intakes per jet (as in the Crew Shuttle Mk2 mentioned above).

To be honest, I nearly always play in sandbox mode so don't care about cost. Given the time it takes to fly jets to space properly, and the part-count limit of my old machine, I generally stick with pure rocket designs, SSTO or not. As to why I bother to SSTO if it isn't for recovery value ... quite often my payloads need to land again, so the 'launch vehicle' actually becomes a shuttle.

[Dewirix]

Although I don't illustrate a vertical-launch wingless jet SSTO as in your illustration they are the most cost-efficient if you can land them close enough to KSC. My designs use turbojets all the way to space (tiny rockets for tiny circularisation burn) rather than basic jets and a heavy rocket engine though. I air-hog, typically 8 intakes per jet (as in the Crew Shuttle Mk2 mentioned above).

Part of the reason I posted the SSTO was because the OP talked about being early into a 0.90 career save with only parts of the tech tree unlocked and that's pretty much the same point I'm at. With more tech I'd definitely go for turbojets over basic jet engines as they're just so much better at high altitude, which in turn would let me go for a smaller rocket for the insertion burn.

I'm a big fan of spaceplanes, but since I don't have even have landing gear unlocked yet I'm limited to tail-sitters or seaplanes.

By-the-by, that's a seriously impressive pair of guides you've put together.

[AstroDoc]

I have been re-reading 'Space Race' by Deborah Cadbury, the book which accompanies the BBC television series (which was shown again on TV in my city recently, and is available on DVD). I recommend the book and the series to all rocket builders. I was interested to read that the Jupiter C rocket design (as stated in the 'A Second Moon' chapter, a chapter covering events in the mid 1950s) had 'The two upper stages were boosted with fourteen small, solid propellant rockets'.