Best Liquid Fuel Engine?

[KerbalNetwork]

I love putting the RE-M3 "Mainsail" Liquid Engine in my rockets, but since it's the heaviest are there any best liquid fuel engines for first stages out there? (no mods please) 

I use the 'Skipper' Liquid fuel engine for my second stage.

 

[Regor]

21 minutes ago, KerbalNetwork said:

I love putting the RE-M3 "Mainsail" Liquid Engine in my rockets, but since it's the heaviest are there any best liquid fuel engines for first stages out there? (no mods please) 

I use the 'Skipper' Liquid fuel engine for my second stage.

 

What tech level?

[KerbalNetwork]

Any tech level would do, since I normally play Sandbox not Career mode.

[TheEpicSquared]

It depends on the size of your rockets. A Mainsail is good for 2.5m rockets, but obviously is overpowered for a 1.25m stack, and potentially underpowered for a 3.75m assembly.

For 1.25m rockets, I usually use the Swivel for smaller stages, since it has good thrust and gimballing. For taller and heavier 1.25m rockets, I usually use the Reliant with 4 Twitch engines as verniers. Works pretty well. 

Also, I like to use a cluster of Thuds sometimes for first stages, as they can really pack a punch and have excellent gimballing range. Usually 4 works fine. 

For 2.5m rockets, using 2 or 3 Vectors would work well, albeit at a ridiculous cost. Alternatively, you could use the Mainsail or a cluster of Swivels or Reliants. Or just use 2-3 Skippers.

For 3.75m rockets, a cluster of 4 Vectors works well, or you can use the Rhino for smaller 3.75m rockets. If you want pure thrust, use a bunch of Vectors or the Mammoth engine.

Hope that helps  

[Kerbart]

Consider installing Kerbal Engineer. You can see how swapping out engines affects DV. I often use a Skipper on lighter 2.5m rockets. If you don't need the thrust it wil save you tons of weight (literally!)

There's no best engine. There's a "most suitable for the job" engine. And that... depends on the job.

[Yakuzi]

'Best' is highly dependent on the situation, i.e. total mass, desired delta-V and TWR.

Have a look at Meithan's engine chart calculator to evaluate what the best engine options are for your specific rocket/scenario. You can find the original thread here.

 

Example of max theoretical deltaV for initial TWR per engine type:

EDIT: double ninja'd

Edited June 9, 2017 by Yakuzi

[cratercracker]

Non-atmospheric landers-

Thud (my fav)

Atmospheric-landers-

Spike

First stage -

A stack of reliants ( 6 or more) with one vector in the middle

Second stage-

2 spike engines

Last stage-

Terrier (if it is a small spacecraft, like my Mk1 or Mk2-individia)

Poodle (for bigger ones)

Vector (for very heave spacecraft)

[Regor]

9 vectors

[overkill13]

I generally only use one main stage with boosters.  I've recently come to love Skippers with assistance from SRBs for a 2.5m rocket.  Mainsail if that just isn't enough power.  

Similarly a Swivel with SRBs usually suffices for 1.25m rockets, though I make use of LF/Ox boosters on heavier payloads using Reliant engines.

I don't find much need for 3.75m and since I play career, at some point I start using Mainsails exclusively to build SSTO launch vehicles which return to KSC.

[KerbalNetwork]

@overkill13 What solid boosters do you normally use?

Edited June 9, 2017 by KerbalNetwork

[Jouni]

Most of my rockets are 2.5 m, 3.75 m, or Mk3, as I almost always play sandbox. I also prefer simple designs, so I tend to avoid complex engine clusters and interstage structures.

For launch vehicles, I have three basic configurations: lower stage + upper stage, lower stage + boosters, and lower stage + payload engines. Boosters require a high TWR and a high sea level Isp, so the appropriate engines are the Vector, the Mainsail, the Twin-Boar, and the Mammoth. First stage engines have similar requirements, but if the boosters are large enough, the Skipper and the Rhino can also be useful. For example, my recent Dres mission was launched with two Twin-Boars and a Rhino:

 

Upper stage engines and other vacuum engines require a decent TWR and a high vacuum Isp. The Poodle, the Skipper, and the Rhino are appropriate for my typical payloads.

 

Finally, small engines such as the Spark and the Terrier are the best for landers. Large engines tend to make the lander tall and unstable, and you rarely need that high TWR anyway.

[Freshmeat]

I use Twin Boar over Mainsail as first stage, always. While the price is of no concern to you, you get a better thrust on first stage, allowing more fuel.

[The Space Dino]

What? Which is the best engine?

This is Kerbal Space Program, we simply just ADD MOAR BOOSTERS

 

Although on a serious note I don't really have too much experience, but for 1.5m I generally use the Swivel, if you want something fancier asparagus staging with a mix of Reliants and Swivels are good. For orbital stuff LV-909 just use it it's so good....

For 2.5 a Skipper with 2 Thumpers seem to be a good choice, although I'm still working on getting more control over the thing, it's kinda unstable

[KerbalNetwork]

@Freshmeat Thank you.

@Jouni What about 1.25m rockets?

 

[Jouni]

@KerbalNetwork I haven't really built 1.25 m rockets since 1.0.4 or so. My general impression is that the Reliant is a booster engine, the Swivel is a first stage engine, and the Terrier is an upper stage/vacuum engine. Using the Reliant in the first stage is a bad idea. The engine doesn't have thrust vectoring, so you need something else for steering the rocket during the ascent.

[Whisky Tango Foxtrot]

For extremely light-weight payloads that for whatever reason won't fit inside a Mk3 SSTO's cargo bay I use a Reliant (with Delta Deluxe winglets for control.) For heavier but still fairly light loads I use a Skipper. Heavier than that, I go with the Twin-Boar. If a Twin-Boar isn't enough I go with a Mammoth, but in practice that's almost never necessary for my launches. For all of these, I sometimes add some SRBs to give it some added punch if the payload is too heavy for a single engine but not heavy enough to justify going up to a more powerful one. I almost never use Mainsails since the Twin-Boar out-does it in nearly every category.

[KerbalNetwork]

I am currently building my second version of my rocket, which has 3 stages. Any LFE recommendations on the third one?

[Starman4308]

8 minutes ago, Jouni said:

@KerbalNetwork I haven't really built 1.25 m rockets since 1.0.4 or so. My general impression is that the Reliant is a booster engine, the Swivel is a first stage engine, and the Terrier is an upper stage/vacuum engine. Using the Reliant in the first stage is a bad idea. The engine doesn't have thrust vectoring, so you need something else for steering the rocket during the ascent.

What I'll sometimes do for heavier 1.25m stacks is have a central Reliant and two Swivels on the side. The Swivel loses a fair chunk of TWR in exchange for a little Isp and gimbal. 

4 minutes ago, KerbalNetwork said:

I am currently building my second version of my rocket, which has 3 stages. Any LFE recommendations on the third one?

You probably don't need three stages to get to LKO, so it seems quite possible to me that you're over staging and should use bigger, longer burning stages. It's been forever since I last played stock, but I'm pretty sure three stages to orbit is overkill unless you're doing something fancy like asparagus staging.

[KerbalNetwork]

@Starman4308  Alright, I'll stay on two stages. What boosters should I use?

[overkill13]

1 hour ago, KerbalNetwork said:

@overkill13 What solid boosters do you normally use?

Usually Thumpers for both 1.25m (2 SRBs) and 2.5m (4 SRBs) rockets.  Though light 1.25s might get only Hammers and heavy 2.5s might get 2 Kickbacks and 2 Thumpers.  I use KER so I can see what booster set I need for decent TWR and Delta-V.

[KerbalNetwork]

5 minutes ago, overkill13 said:

Usually Thumpers for both 1.25m (2 SRBs) and 2.5m (4 SRBs) rockets.  Though light 1.25s might get only Hammers and heavy 2.5s might get 2 Kickbacks and 2 Thumpers.  I use KER so I can see what booster set I need for decent TWR and Delta-V.

Thanks for that, even tho I already put those on my rocket.

[NSEP]

The KS-25 is really amazing for launch, yet expensive. I now really like the Ant alot more than before. The 1KiloNewton Thruster in RO gave me more love for low TWR engines.

[Julien Kerman]

I always used a 2.5m to 2x 1.25m adapter with two KS-25 Vector engines.

Examples:

[Mastikator]

The Mammoth has the highest TWR and Isp at sea level. It's the best by those metrics.

[GoSlash27]

The "best" engine is whichever one makes the lightest/ cheapest stage. It depends on your payload, environment, and DV/TWR requirement and varies far too much to point at a single engine. 

Best,
-Slashy