When in doubt, cluster some Mainsails.

[SlabGizor117]

Can lift 715 tons with a TWR of 1.02... k den.

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[Whirligig Girl]

Here's a better embedding m8.

[EdFred]

Is that right? Only 1:49 of fuel burn for that much fuel?

[sdj64]

Is that right? Only 1:49 of fuel burn for that much fuel?

I think there are no fuel lines to the side tanks.

[michaelhester07]

I stick to my Ultima-13 design (its the honeycomb on the bottom)

Almost single stage to orbit 400ton payload for less than 1 million funds. (not seen was the solid booster set on the ends).

Start with the core: 2x large kerbodyne tank, 1x KR-2L engine on the end.

Duplicate the core, attach with 6x multiplier. Duplicate the core again, attach to the 6x radial engines so that the edge of the new tanks nearly touches the edge of the previous ones, forming a honeycomb formation.

Triangular strut the outer tanks together.

It sat on the pad without clamps and surprisingly didn't break, and gets a 400ton payload to orbit with nearly 4000 delta/v in the stage.

I use the KR-2L instead of the 4 bell engine for 2 reasons:

Before .90 the 4 bell engine wouldn't place because it clipped.

The KR-2L is slightly more efficient at higher altitudes than the other engine.

Edited April 1, 2015 by michaelhester07

[SlabGizor117]

Here's a better embedding m8.

Noice m8, thanks! I r8 emb3dding 8/8.

-

I think there are no fuel lines to the side tanks.

Ahh, forgot. I just quick-built it to see what it could lift, thought it was cool, and posted

It sat on the pad without clamps and surprisingly didn't break, and gets a 400ton payload to orbit with nearly 4000 delta/v in the stage.

Wow... How? I struggle with my 80 ton lifter, although I'm an aesthetics .... about it, too.

[michaelhester07]

I have no idea how it didn't break the pad... or an engine or two. I hit the launch out of the VAB editor.. went "oh... i forgot launch clamps". The rocket sat there ready to launch, pad and all intact. I guess the weight got distributed over all of the engines equally.

[samstarman5]

Is that right? Only 1:49 of fuel burn for that much fuel?

Pretty much. Just the other day I tried 4 mainsails instead of the larger engines for that size tank, and just watched the fuel disappear. Probably didn't even make 2km above the launchpad.

[Vashts]

mainsails are life

[Jovus]

He who controls the mainsails, controls the universe.

[kStrout]

I use 5 mainsail clusters all the time for gigantic rockets, they have wonderful thrust and look very awesome and ligit(compared to making giant pancake rockets)

[G'th]

Pfft, cluster Saturn V's and we'll talk. (or get on Whackjob's level and use mainsails as sepratrons)

[Foxster]

Might look cute but the TWR is awful.

Just two mainsails weigh in at 12t and have 3000 thrust. One S3 KS-25x4 weighs 9.75t and has 3200 thrust. ISP is the same for both.

This is a proper fat-arse rocket...

3 x the thrust, better TWR and better ISP than a S3 KS-25x4.

Edited April 2, 2015 by Foxster

[SlabGizor117]

Pretty much. Just the other day I tried 4 mainsails instead of the larger engines for that size tank, and just watched the fuel disappear. Probably didn't even make 2km above the launchpad.

Well if you look back, to my reply, it has no fuel lines from the radial tanks. Radial tanks don't automatically feed into the central one without fuel lines.

Might look cute but the TWR is awful.

Just two mainsails weigh in at 12t and have 3000 thrust. One S3 KS-25x4 weighs 9.75t and has 3200 thrust. ISP is the same for both.

This is a proper fat-arse rocket...

3 x the thrust, better TWR and better ISP than a S3 KS-25x4.

I suppose, but in comparison as far as one KR-2L though it looked pretty wimpy compared to the mainsail, only 2500 compared to 1500 of an engine around half it's size, but if you cluster them, maybe...

Also, your cluster is ^{​off center D:}

[Foxster]

Makes some very phallic rockets though

[Whackjob]

Pfft' date=' cluster Saturn V's and we'll talk. (or get on Whackjob's level and use mainsails as sepratrons)[/quote']

I see this is covered already, haha! *hat tip*

[SlabGizor117]

very phallic rockets

My vocabulary has failed me again... In more ways than one...

Thanks Google Dictionary. ಠ_ಠ

[Falcon Coupe]

I have a rocket using 5x KR-2Ls as an upper stage, ain't got no time for mainsails!

[bakanando]

The KR-2L might be nicer ISP in vacuum, but the KS-25x4 has a better efficiency on atmosphere. A combination of both engines might be a better lifting design.

[Lupus Irae]

May I ask what parts those are connecting either the Mainsails or KR-2L's?

[Arsonik]

May I ask what parts those are connecting either the Mainsails or KR-2L's?

Looks like the Mk3 -> 2m adapter and 2m -> 1.25m adapter from the last update. Not sure though.

[Foxster]

The KR-2L might be nicer ISP in vacuum, but the KS-25x4 has a better efficiency on atmosphere. A combination of both engines might be a better lifting design.

That's not quite true, the KR-2L do generally have better ISP in atmos too, despite their stats.

The S3 KS-25x4 has a listed ISP of 320 atmos and 360 vac, the KR-2L is 280 and 380, making the first sound better for atmos work. However, this is not binary, where a switch between ISPs happens at edge of the atmos. In fact, the KR-2L reaches an ISP of 360 by 8km! Meaning that it has better ISP everywhere except the first 8km. Admittedly, with a big rocket, you can use a lot of fuel by 8km, but the better TWR makes up for that over a whole launch.

So, for a heavy lifter, there really is no reason to use the S3 KS-25x4 over multiple KR-2Ls, apart from part count.

- - - Updated - - -

May I ask what parts those are connecting either the Mainsails or KR-2L's?

For the KR-2L's I use a 'Mk3 to 2.5m Adapter Slanted' with a 'C7 Brand Adapter Slanted - 2.5m to 1.25m' on top. These are half-clipped into a S3-7200 tank, along with a fuel duct.

That's for aesthetics, though the tanks are obviously useful. You could just as easily stick three or four KR-2Ls on the bottom of a S3-14400 with some Cubic Octagonal Struts.

Edited April 2, 2015 by Foxster

[Flixxbeatz]

Mainsail clusters you say?

Not to mention it also looks sleek.

[Foxster]

Just for my own use I decided to test if the above holds up. I'm recording it here in case anyone else is interested, sorry to go off topic.

I built two ships. Both with 8000kN of thrust and 24 x S3-14400 tanks. One with S3 KS-25x4s and the other with KR-2Ls. I wanted to see how they compared to 10km and 100km orbit.

Here's how they compared:

S3 KS-25x4

25 engines give 8000kN thrust.

Vehicle weight: 2217t (1968t fuel + capsule etc)

dV: 4746 atmos, 5340 vac at launch

At 10km

dV: 2832/3186

Weight: 1205t

100km Orbit

Couldn't get it to orbit, out of fuel. Flew like a drunken pig, probably not helped by the minimal gimbal range. Had to add reaction wheels (also added to other craft for fairness) just to keep it vertical.

KR-2L

32 engines give 8000kN thrust.

Vehicle weight: 2182t (1968t fuel + capsule etc)

dV: 4317 atmos, 5858 vac at launch

At 10km

dV: 3024/4104

Weight: 1363t

100km orbit

Flew nicely to orbit, helped probably by high gimbal range.

1092dV left

Conclusion

In all ways, the KR-2L ship out-performed the S3 KS-25x4 ship. It weighed less, used less fuel to 10km and to 100km orbit. It handled better. There are attachment points on the bottom of the engines. It even looked better. Much quieter too.

I know you wouldn't usually take S3 KS-25x4 to orbit so that's not a great test but the 10km results are significant.

[Johnny Wishbone]

For the KR-2L's I use a 'Mk3 to 2.5m Adapter Slanted' with a 'C7 Brand Adapter Slanted - 2.5m to 1.25m' on top. These are half-clipped into a S3-7200 tank, along with a fuel duct.

You can clip them in such a way that the fuel duct is unnecessary. They will automatically draw fuel from the center tank.

I have an engine that clusters 5 of the KR-2Ls in a similar fashion as yours and I do not need fuel ducts.