Standard Lift Subassemblies

[Fearless Son]

I rarely use standard lifters, and the few times I do use them, I use them because they are meant to be reusable.  Like, when I have a bunch of expensive Mammoth and Vector engines with lots of large fuel tanks, I might want to recover them and use them for multiple launches.  But recovering those lifting vehicles requires over-engineering them somewhat, which is what makes turning them into subassemblies practical.  

Otherwise, I just slap some tanks, engines, and stabilizing surfaces that seem like they ought to be enough, then add twenty percent moar boosters than I think I need.  That tends to get me to orbit quickly enough.

[SnakyLeVrai]

52 minutes ago, Tyko said:

For those using standard lifters - What do you do if your payload falls between two of your standard lifters?

I usually use the bigger lifter - KSP doesn't model this well, but IRL it would be cheaper to use an over-spec'd lifter that's already designed versus spending the time / money to modify it. In-game it saves ME a ton of time, but feels a bit wasteful.

I'm just wondering if others go the same route or have a better solution.

Yeah I use the bigger one too. The difference between the 2 is usually small enough that it's not over-expensive. I have reusable launchers as well, around 70-80% of the launcher's price is recovered as far as I am concerned (I lose the fuel and the fairing).

[Wcmille]

6 hours ago, Tyko said:

For those using standard lifters - What do you do if your payload falls between two of your standard lifters?

I usually use the bigger lifter - KSP doesn't model this well, but IRL it would be cheaper to use an over-spec'd lifter that's already designed versus spending the time / money to modify it. In-game it saves ME a ton of time, but feels a bit wasteful.

I'm just wondering if others go the same route or have a better solution.

I also use the next biggest lifter. My lifters are about 5 tons apart in the 15-65 ton range.

[StrandedonEarth]

On 1/4/2018 at 10:00 AM, Tyko said:

where at 1.2 I feel like I'm wasting a lot of fuel doing just slightly more than hovering.

This makes me go hmmm..... How are you calculating TWR? If you're using KER or something similar, for liftoff TWR make sure you have the "Atmospheric" button checked. 1.3-1.4 vacuum usually translates to around 1.2 on the pad depending on engine. 1.2 vacuum, however, can end up under 1.1 on the pad.

If calculating by hand, make sure to use ASL Thrust.

As to the OP, I re-use lifters when I can, and tweak or custom-build when I can't. Eventually I have a booster for everything.

OTOH, I have a "Space Camp Bus" that has had the main design frozen and the .craft file copied forward since 1.1. I really don't want to have to rebuild it.

Edited January 12, 2018 by StrandedonEarth

[Wcmille]

All my figures assume vacuum thrust and Isp.

[ExtremeSquared]

Gone are the days where basic interplanetary missions required an intricate lacework of struts and fuel pipes holding dozens of small 2.5m tanks together. Those lifters took a fair amount of time and testing to build. Now lifters are the most painless part.

[GoSlash27]

I don't commonly use standard lifters, but I do use the same vehicles fairly frequently. I agree with @OhioBob on the t/w question, since I'm a "career" guy and the most important considerations in career mode are 1) cost per tonne and 2) reliability/ ease of use. My lower stage is 1.2 t/w minimum and my upper stage is 0.7 minimum. lower stage t/w computed at 1 atm and upper stage computed at vacuum.
 Both stages generate roughly 1,700 m/sec DV each. Lower stage computed at 1/2 atm, upper computed at vacuum.

Best,
-Slashy

Edited January 12, 2018 by GoSlash27

[IncongruousGoat]

It depends. In stock or lightly modded installs I usually don't bother, since it's typically trivial to throw together a new booster for each mission. For RSS/RO, on the other hand, I definitely use standardized booster families, each one tuned to a specific set of payloads. It's A: more realistic, and B: time-saving, since it can take hours to design and test a new booster design.

[Alpha 360]

I love to use standardized command capsule sub-assemblies. Those are just the best, being multi-purpose and just looking cool to have several of them attached to a space station. Boosters though..... 

I agree with Slashy about Boosters being easy to through together, especially if one has Kerbal Engineer to tell you if you have enough Delta-V to reach orbit. Not that it is accurate sometimes, but that it gives a general direction. 

Sometimes though it is fun to have a multi-role booster like the BFR is going to be instead of a Saturn V. Usually through it overcompensates or undercompensates which means modifications to the booster have to go through and therefore, there is no one size fits all rocket, except maybe a SSTO. 

[GoSlash27]

1 hour ago, Alpha 360 said:

I agree with Slashy about Boosters being easy to through together, especially if one has Kerbal Engineer to tell you if you have enough Delta-V to reach orbit.

Alpha 360,
 Actually, I wasn't the one who said that, but I do agree. I also don't KER, but rather an even lazier tool: A spreadsheet using the reverse rocket equation. I tell it what I need the stage to do, and it tells me what I need to build, how much it will cost, and how much it will weigh.

Best,
-Slashy

 Somebody upstream asked what we're seeing for cost/ tonne to orbit? Excluding the cost of the payload itself and assuming no recovery, under $2000/tonne if I'm not really trying (serial staged liquid fuel), and as low as $600/tonne if I am (quasi-asparagus SRB types).
 

[Geonovast]

1 hour ago, Alpha 360 said:

I love to use standardized command capsule sub-assemblies

I've got a couple subassemblies like this.  I got tired of putting parachutes, LS, docking port, etc on the MK1-2 (Pretty much the only capsule I use), so I made one for that.  Call it the SKREP.  Don't have a pic as I'm not home.

I've also made a few for relay satellites, ore drones, stuff like that.

[Alpha 360]

Wow. That's pretty lazy Slashy. Sounds right up my alley. Where is this spreadsheet?

Geonovest, have you heard of the Tantares mod? That mod is mandatory for me by now, giving the largest range of new command pods than any other mods. Its just spectacular and command pods are no longer just a Mk 1-2 command pod + hitchhiker with all the xtras. Would also recommend the Near future Solar mod for fancy solar panels for the command pod subassemblies. 

[GoSlash27]

Alpha360,
 It's on my desktop Writing it myself was the non- lazy part...
I can kick you a copy if you want.

Best,
-Slashy

[Tyko]

19 hours ago, StrandedonEarth said:

This makes me go hmmm..... How are you calculating TWR? If you're using KER or something similar, for liftoff TWR make sure you have the "Atmospheric" button checked. 1.3-1.4 vacuum usually translates to around 1.2 on the pad depending on engine. 1.2 vacuum, however, can end up under 1.1 on the pad.

If calculating by hand, make sure to use ASL Thrust.

As to the OP, I re-use lifters when I can, and tweak or custom-build when I can't. Eventually I have a booster for everything.

OTOH, I have a "Space Camp Bus" that has had the main design frozen and the .craft file copied forward since 1.1. I really don't want to have to rebuild it.

I'm using KER and using it properly...thanks for the suggestion though.

When I said 'hovering' I was exaggerating a bit...yes the rocket goes up but slowly. The slower it accelerates the longer it takes to get to orbit and the more fuel it's going to burn. 1.2 TWR is a really slow start.

[GoSlash27]

5 minutes ago, Tyko said:

When I said 'hovering' I was exaggerating a bit...yes the rocket goes up but slowly. The slower it accelerates the longer it takes to get to orbit and the more fuel it's going to burn. 1.2 TWR is a really slow start.

True, but burning extra fuel is cheaper than discarding extra engines.

Best,
-Slashy

Edited January 12, 2018 by GoSlash27

[SnakyLeVrai]

Here is an update with the cost/t, including wit recovery between brackets (and a new name : the Peach Pie series, replacing the Minus one  ). There are some values I did not record... You can guess it's not often I launch the Pea Pusher, nor do I fire a Pièce Montée frequently...

Makes me think I should maybe reengineer the Peach Pie serie to lower the cost... 

Standard assemblies are great, when I deploy the communications networks I have all the satellites already built, I only need to cluster them up on a good ol' chemical propulsion deep space tug and there I go. It's less expensive to build, although it requires a bigger rocket to launch - the cost/t is still very low and I take full benefit of high TWR in space, which make burns a hell of a lot less annoying.

I use std assembly for base building as well, I have standard supports with 4 legs and docking ports, they are stackable in a rocket's fairing and all.

Also, std assemblies come in handy for test benches, like this one I've got to test the resistance of landing legs. When I obtain the landing speed through RCSBuildAid (parachutes), I calculate how I should adjust the test bench's height to drop the payload, so it lands on the launchpad at the same speed and check for any damage... That's handy when you have to drop a large base on Duna with tenuous air to brake in... Specially if you have sensitive stuff on the belly of the payload. It's a good way to check if your landing legs extend long enough so nothing gets kerbaled to smithereens, due to compressibility of the legs on impact. Engineering tools!

[Wcmille]

6 hours ago, GoSlash27 said:

Alpha 360,
 Actually, I wasn't the one who said that, but I do agree. I also don't KER, but rather an even lazier tool: A spreadsheet using the reverse rocket equation. I tell it what I need the stage to do, and it tells me what I need to build, how much it will cost, and how much it will weigh.

Best,
-Slashy

 Somebody upstream asked what we're seeing for cost/ tonne to orbit? Excluding the cost of the payload itself and assuming no recovery, under $2000/tonne if I'm not really trying (serial staged liquid fuel), and as low as $600/tonne if I am (quasi-asparagus SRB types).
 

I'd love to get pics or craft files of lifters that are < 900 per ton.

[GoSlash27]

Wcmille,

https://i.imgur.com/TTd3hTA.jpg

$780/ tonne

https://i.imgur.com/qudtYyO.jpg

$690/ tonne

A lot of good tips 'n tricks in the "Cheep & Cheerful Challenge"

Best,
-Slashy

Edited January 13, 2018 by GoSlash27

[Geonovast]

On 1/12/2018 at 2:50 PM, Alpha 360 said:

Geonovest, have you heard of the Tantares mod? That mod is mandatory for me by now, giving the largest range of new command pods than any other mods. Its just spectacular and command pods are no longer just a Mk 1-2 command pod + hitchhiker with all the xtras. Would also recommend the Near future Solar mod for fancy solar panels for the command pod subassemblies. 

I think so, don't have it though.  I do have several mods that add command pods, I just really like the MK1-2.  We have a history together.

Here's the SKREP.  I know it could be more effecient to use a prebuilt for less parts, but eh.

It has 260 m/s of dV.  A big bonus is the Konstruction! docking port at the top, for the angle snap docking.

[Alpha 360]

You are using Kerbalism! I must have tried that mod at least three times. Each time a failure.

[Geonovast]

1 minute ago, Alpha 360 said:

You are using Kerbalism! I must have tried that mod at least three times. Each time a failure.

I am?

[Alpha 360]

Sorry, just isn't those recyclers from Kerbalism? I was pretty sure I used those with the Kerbalism mod installed. If not, what life support mod have you installed?

[Geonovast]

I have TAC installed, but I believe those small radial tanks are from Universal Storage(Which is incredible, one of my required mods, even without LS.)

[Alpha 360]

Oh, just another circumstance of talking (writing) without thinking. Does SKREP stand for something or is it just an interesting name you came up with.

[Geonovast]

1 minute ago, Alpha 360 said:

Does SKREP stand for something or is it just an interesting name you came up with.

Upper left of the SS