Mk-55 "Thud" Liquid Fuel Engine

[Sharpy]

Stick on top of a rover, facing backwards, for extra thrust uphill

Multiple engines instead of one *will* hurt delta-V, but at gain of thrust. In planetary launch scenarios thrust is what allows you to escape gravitational drag, so the benefits may outweigh more delta-V at poor TWR.

Thuds make nice engines for MK3-based landers. The MK3 parts are quite durable to impact, so they don't require landing legs if you stick nothing below them. The MK3 to 3.75m adapter is one of my favorite lander bases; a wide, flat circle with a plenty of room to attach everything you need on top, 50m/s impact resistance, heavy enough that you need to try really hard for it to tip over, a single piece with nothing to break or fall off when you land it, and more than enough fuel to lift the lander to orbit from most moons. But it needs radially attached engines and you can either go with radially attaching tanks, engines to these and fuel pipes from the adapter to the small tanks, or several Twitches (even worse ISp and very poor thrust for a part this heavy) - or Thuds.

[Mars Mullo]

I have noticed that all the results from the Optimal Kerbal rocket design web site have multiple Thuds as a cheaper or most cost efficient option.

Typically requiring odd numbers of them.. 5 or seven per stack of seven tanks ... basicly making a big multiple burning rocket pair. They work very well. And are CHEAP.

[AG5BPilot]

I had a booster where the 1st stage main (center) section was just a little low on TWR after the SRBs fell off. I used a pair "Thud" engines that activated at SRB sep to augment the main engine. I think that's the only time I've used it.

[JayKay]

I use 4 Thuds around the bottom of the rocket early in my career to boost the thrust of the Skipper on the main stage until the Mainsail is available.

JK

[selfish_meme]

As Sharpy said, mk3 cargo delivery to planet, see Runes base in a box. I am using it for the same thing Ares Mars Direct base delivery (no no I did not steal his designs at all ). 2 are enough twr for a nice delivery dunaside.

[KingPhantom]

i often used them on big-pod sized landers. so i was able to build a science bottom and left that behind. i returned with the pod, a tank and 3 mk55 radial mounted to the tank.

[Jouni]

The Thud is a niche engine for a niche that isn't very relevant for most players. It was quite useful as a lander engine in 0.90, but 1.0 repurposed it as a launch engine, in which role it's outclassed almost immediately by the Skipper. I used the Thud once in the Caveman Challenge, but otherwise I haven't touched it in 1.0.

[A_name]

Hello, fans of this engine (there are fans for everything so there must be some fans for this) and others (including me), I would like to ask what this engine is good for if anything at all.

It is radially mounted, but it has some problems, namely:

1. It comes in at the same time as the Terrier and the Poodle is just one node away; making it a rather unconventional choice for a vacuum engine.

2. Since it's radially mounted you must use symmetry of some sort; as such you'll always have more than one Thud and that's not good for Delta-V.

What do you have to say about the Thud?

Late to the party so this has probably been said already but I find it useful when I need a bit of extra thrust on liftoff. Strap a few on the sides of your central stack.

[Bioman222]

I made a pretty stinking good VTOL with two of them:

[Brofessional]

Occasionally I'll slap a few of them on the first-stage if I my TWR needs a boost.

[Xyphos]

I use Thuds on Action Group toggles, use them as RCS control on large VTOL ships.

[Alchemist]

I clipped them into R-7

[Thomassino]

I have used them only in my early career, when I got a contract to test it. I clipped it into the center of fuel tank to act as normal, inline engine. Never used them on any skycrane I have build yet. I always used inline engines.

I noticed it has a very decent gimbal, so it would be good to use them as vernor engines.

Yaay 100th post

[CaelumEtAstra]

I have used the MK. 55 on my Centaur 2.5 & 3.75m launchers to provide extra thrust and greater control authority. Granted, I'm playing on a heavily modded sandbox game, so that might not be all that relevant. Other than that, I haven't used them for anything else. Might make a good OMS for my Shuttles and SSTOs, now that I think about it.