need info about engine clusters and radial engines

[grim5000]

I'm in need of info on engine clusters. I'm unsure about when to use them, what kind of and how many engines should/could replace what engine, and other stuff like that.

I am also wondering when it's best to use radial engines and how to tell what kind and how many i should use.

Any help is greatly appreciated.

[Franklin]

when you say radial engines do you mean parallel engines? in the case of efficient lifting parallel engines, always eat your asparagus

[numerobis]

Radial engines are easy to attach radially, and shaped to stay out of the way; that's the only benefit they have -- but it's a benefit worth looking in to for a lander. The radial engines available in-game are worse in every other respect than the main engines.

Understanding engine clusters demands understanding the basics of why one engine is better than another. If you don't understand Isp and TWR and thrust vectoring, read up on those in various tutorials.

Once you understand those characteristics, you can compare things like: do you prefer a Skipper engine versus a cluster 2 T30s and 1 T45? Both have some vectoring thrust, which helps you go the right direction on ascent. The Skipper is 4 tonnes, whereas the cluster is 3.75 tonnes. The Skipper yields 650 kN whereas the cluster only yields 630 kN. The Skipper uses more fuel: Isp is 350s versus 370s for the cluster. The cluster is 5 parts to attach the engines, whereas the Skipper is one part (which matters for frame rate). For a short stage, it's a toss-up; the longer you go, the more you can benefit from that improved efficiency.

[capi3101]

I'll direct you to the parts list on the wiki. It has all the information you need on...well, everything, engines included.

In my experience, engine clusters are best used when an individual engine either provides too little thrust for what you need or too much, and that usually goes back to asparagus techniques. Temstar discusses it pretty well in this thread.

They're also useful when you're not far up the tech tree and need some oomph. Stick 4 LV-T30s on the end of Tail Connectors attached to the side of a tank and add a Skipper. You've got an engine cluster that provides the slightly more thrust than a Mainsail engine, with better Isp. The downside is another 1.6 tonnes (for the Tail Connectors); if it weren't for that little factoid, it'd be a superior choice to the Mainsail (that and you're talking about adding nine parts instead of just one).

[numerobis]

You can attach engines on trusses also: set the truss up radially on the tank, rotate it once so it points down, then attach the engine on that. Much lighter than a tail connector: 0 for a cube strut, 125 kg for a truss, 400 kg for a tail.