Poll - what rocket engine do you use the least / forgot about?

[Firemetal]

I ignore the ant and spider engines. Even more the spider since I used an ant on my first attempt at the under 50 ton Moho challenge. It was trash for that. Bad TWR.

Fire

[Whisky Tango Foxtrot]

I find the Puff engines to be very useful in some situations. They're great if you want to build a craft with RCS capabilities but that's too small to use either Vernors or a dual-fuel setup. I wouldn't say that I use them particularly often, but they've come in handy on more than one occasion.

[septemberWaves]

On 2/14/2017 at 1:00 PM, AeroGav said:

Vector - too heavy and powerful for space shuttles , causes CoM issues.

Really? On my latest shuttle prototype the three Vectors actually solved the center of mass issues. In fairness the first test flight to orbit and back lost control on re-entry, but that was because I lacked sufficient pitch control rather than being anything to do with the center of mass.

 

As for the topic of this thread, the engine I use the least currently is the Twin Boar, because it's really just overly powerful for a Kerbin ascent at stock scale. That's likely to change once I start needing larger and larger launch vehicles in my 4x scale long-term career though; I don't have much science left to gather before I could unlock the Twin Boar (though it'll still take me a while because I have low science returns and other research priorities) and once I do I get the feeling that it'll be very useful.

Edited February 16, 2017 by eloquentJane

[Temeter]

I never use the Puff, but I never forget about it, because it's utter uselessness is a shining example.

Also rarely using the dawn; in particular now, with solar panels scaling with sun distance, that thing is kinda useless.

Weird so many people don't like the aerospike. IIRC it's more powerfull (t/w) than the other 1.25m engines, at higher efficiency. Bit expensive for the career, tho.

Edited February 16, 2017 by Temeter

[Freshmeat]

The price of the aerospike kind of closes it for me, I don't do spaceplanes (Rapier), and I have yet to use the Puff. I think I have used every other rocket engine in my current career.

[foamyesque]

I just haven't been able to figure out a decent use for the aerospike in several versions. They used to be absolutely fantastic for Kerbin and Eve missions, but they're surpassed in various ways by other engines; the Reliant's lighter, cheaper, and more powerful; the Swivel has TVC; the Mammoth does monster lifts, the various vacuum engines are more efficient in space, etc. Even the Puff gets more love, for when I'm looking to build really tiny things where two kinds of tanks would be a pain.

I also don't use the Twitch much. The Spark is just flatly superior.

The Dawn is a fantastic engine for its niche. It gets surprisingly good TWRs for it, too. People just put too much fuel on the things. Unfortunately, it can't be refuelled, which limits its use otherwise.

 

 

 

 

[Whisky Tango Foxtrot]

6 minutes ago, foamyesque said:

I also don't use the Twitch much. The Spark is just flatly superior.

The one advantage the Twitch has over the Spark is that it can be radially mounted, which is really useful for landers with docking ports on the bottom (which I use extensively.)

[foamyesque]

Just now, Whisky Tango Foxtrot said:

The one advantage the Twitch has over the Spark is that it can be radially mounted, which is really useful for landers with docking ports on the bottom (which I use extensively.)

The spark can also be radially mounted, trivially, and maintains its TWR and Isp advantages

[eddiew]

Probably the Rhino... By the time I'm in vacuum, I rarely need a 3.75m engine. Feels like if I'm not using nervas for vacuum, I've done something wrong in the design stage!

Spider/Twitch... poor ISP, can't see the point in them. What you save in mass you lose in efficiency. I'd rather put Ants out on the sides, if I absolutely have to use radial engines.

Weirdly I do put Puffs on stations even though they're less efficient than Twitches. My stations tend to have monoprop tanks to top up visiting vessels, and having a little bit of manoeuvring capability can be handy.

[Tweeker]

You forgt one....

          The Poodle.

[Cunjo Carl]

Thud... That TWR... why!?

[GoSlash27]

1 hour ago, Tweeker said:

You forgt one....

          The Poodle.

Sacrilege! The Poodle is like Frank's Red Hot; I use that *%&^ on everything!

 

[Allocthonous]

41 minutes ago, GoSlash27 said:

Sacrilege! The Poodle is like Frank's Red Hot; I use that *%&^ on everything!

 

While I don't actually know what Frank's Red Hot is, Poodles are fantastic.

Also, I recant my opinion on the Twin Boar; it's pretty useful. And its exhaust is a pretty color, which is always a plus.

So, for those of you who dislike the ant, what do you put on tiny satellites? Are you just not using tiny satellites, or what? A .5 meter fuel can, a battery, a probe core, an antenna, and solar panels are just the right size for the ant to move, and if you turn its thrust limiter down to half a percent you can manage meter-length orbital adjustments without too much fuss.

[Blaarkies]

19 hours ago, foamyesque said:

I just haven't been able to figure out a decent use for the aerospike in several versions. They used to be absolutely fantastic for Kerbin and Eve missions, but they're surpassed in various ways by other engines; the Reliant's lighter, cheaper, and more powerful; the Swivel has TVC; the Mammoth does monster lifts, the various vacuum engines are more efficient in space, etc.

The extra TWR from Reliants come at a price of poor Isp and a much larger size. The aerospike has great TWR and enough Isp to compete against Terriers, even though it has 5 Isp less it also needs less engine mass to deliver the same thrust.

What makes the Aerospike great is it's ability to be used both in atmosphere and in space...but when using it for only one of those it loses against highly specialized engines.

[KerikBalm]

22 hours ago, eddiew said:

Probably the Rhino... By the time I'm in vacuum, I rarely need a 3.75m engine. Feels like if I'm not using nervas for vacuum, I've done something wrong in the design stage!

Spider/Twitch... poor ISP, can't see the point in them. What you save in mass you lose in efficiency. I'd rather put Ants out on the sides, if I absolutely have to use radial engines.

Weirdly I do put Puffs on stations even though they're less efficient than Twitches. My stations tend to have monoprop tanks to top up visiting vessels, and having a little bit of manoeuvring capability can be handy.

Rhino's are great for when you've got a ~2 km/s ejection burn to Jool/Moho/whatever, and you're sending a large mission (like a large crew habitat). Eject payload on course, decouple, burn retrograde, aerobrake a bit and refuel the 3.75m ejector. Even more practical after part autostrutting was introduced, making docking connections less wobbly.

Twitch I use, its the even smaller spiders that I rarely use. The twitch has 80% higher TWR than the spider.

Even though I use thuds when I want large radial engines, its just for part count. Multiple Twitch would be better. The Thud TWR is quite bad. I only use them for high thrust low dV maneuvers, so I don't mind their lackluster Isp. Their lackluster TWR though is the main reason why they aren't used much.... after all, the poodle has a better TWR.

[George van Doorn]

11 hours ago, Tweeker said:

You forgt one....

          The Poodle.

Well, I "forgot" many, because, let's be serious ;). I only added Mainsail not to have 13 options in the list :).

[astroheiko]

The only engine I never use is the "Puff".

What I do not understand is that someone never uses the "Dart". You need 3 "Terriers" to have the same thrust and then have a half a ton more weight. It also works much better in the atmosphere and has almost the same ISP in the vacuum. Can not understand how the 16.5% come about.

Also the "Vector". This together with the "Dart" - for me the only reasonable way to get away from Eve without a huge ship.

I also often use the "Dawn". Light probes with dV far more than 15000 m/s. For example, I use these probes to perform several fly-bys.

Am I lying so wrong?

[astroheiko]

On 16.2.2017 at 8:58 AM, foamyesque said:

I just haven't been able to figure out a decent use for the aerospike in several versions. They used to be absolutely fantastic for Kerbin and Eve missions, but they're surpassed in various ways by other engines; the Reliant's lighter, cheaper, and more powerful.

Sorry for the inconvenience, but this is the wrong way. Just because it is easier it does not have to be better, By the better ISP the dart makes the extra weight more than good You need substantially less fuel.

I have built an example: Here is a rocket with the Reliant: TWR 2.31 and 4295 dV 

 

Here is the rocket with a Dart. Here you can see well what you can save. Higher TWR (2.44) and slightly more range of 4392 m / s dV. And only because of the fuel saved by the higher ISP.

 

I really do not want to sound opinionated, but the Dart outmatches the Reliant in every sense.

 

Greetings

[foamyesque]

@astroheiko: You're correct that the Isp advantage can compensate, but if you're putting four and a half thousand dV into one chemical stage you're overbuilding it. The Dart's heavier weight impedes balancing craft in atmosphere and it is awful in vacuum compared to things like the Poodle or Terrier. I suspect you'd find that, if you re-ran the numbers for a more typical chemical stage dV target of 2.5km/s, that the Reliant outperforms it.

[astroheiko]

29 minutes ago, foamyesque said:

@astroheiko: You're correct that the Isp advantage can compensate, but if you're putting four and a half thousand dV into one chemical stage you're overbuilding it. The Dart's heavier weight impedes balancing craft in atmosphere and it is awful in vacuum compared to things like the Poodle or Terrier. I suspect you'd find that, if you re-ran the numbers for a more typical chemical stage dV target of 2.5km/s, that the Reliant outperforms it.

Ok, now I have quickly built a cargo of 6 tons and the appropriate first stage with 2500 m/s dV. The Reliant engine can just take off (TWR Surface 1.07).

The same with the dart and correspond to less fuel but the same range: Does not lift (Surface TWR 0.91) whether the entire rocket is lighter.

In this case, you are right. The controllability also comes to this.

So:  the Dart outmatches the Reliant in not every sense.

So I have to apologize and hope you forgive me. Since we can see again that not everything is black or white, there are fine differences.

 

Greetings

Edited February 17, 2017 by astroheiko

[Tweeker]

11 hours ago, George van Doorn said:

Well, I "forgot" many, because, let's be serious ;). I only added Mainsail not to have 13 options in the list :).

I can agree that the Poodle deserves to be forgotten.

But seriously, what do you use the Poodle for?  In almost every case where you use a Poodle you can make the rocket better by swapping in a different engine.

 

 

[cantab]

Gotta be the Puff. I've just never really tried to build with it. I'm not sure what I'd use it for. Anything small enough that I'd particularly want to go monoprop-only is probably small enough to just use RCS thrusters for all propulsion. The terrible efficiency combined with the terrible mass ratio of the monoprop tanks rule it out of anything requiring a decent amount of delta-V. And the terrible sea level performance means it would be a lousy LES.

I also don't think I've used the Spider since it got gimped. Lower efficiency compared to the Ant is just a major minus for its expected use cases. The Twitch suffers the same problem.

I used to not use the Poodle much either, but now I've been playing RSS lately and it's really come into its own as an essential upper stage engine. On the other hand it's the Skipper that's getting ignored, because the need for increased TWR in lower stages means I go straight from Poodle to Mainsail.

My remarks on some other engines:

Dawn - It's the easiest option for extreme delta-V needs. Maybe you've never done something that needed over 10 km/s without refuelling. I don't use it that often, but when I do it's to do something that would be far more difficult without it.

Rhino - Useful? Debatable. BadS? Absolutely.

Thud - Has a niche for a lander that needs about the same thrust as a Swivel but would be too tall with a single central engine.

Twin Boar - Taking into account it baically includes an orange tank - and how often would you want less fuel with a 2000 kN engine? -  it's the highest TWR liquid engine and great value in career. And in RSS I've been mounting a Mainsail under a Twin Boar to get the power I need without having unlocked 3.75 m parts.

Ant - I've used this, and often regretted it! For anything that's not very tiny I end up with longer burns than I'd like and wishing I used a Spark. (And I know, I'll do the long burns with the Dawn, but that's because they're worth it, the same burn time with a chemical engine's puny delta-V is not.)

EDIT: I also used to think the Mainsail had been eclipsed, by the Twin Boar and Mammoth. Then, as mentioned above, I started using it as an upper stage engine in RSS.

Edited February 18, 2017 by cantab

[Whisky Tango Foxtrot]

The Poodle is a great engine for circularizing in LKO; the NERV often just doesn't provide enough thrust to achieve orbital velocity before falling back into the atmosphere. I also play with a self-imposed rule to avoid firing NERV engines in-atmosphere for environmental reasons (I'll do it in an emergency, but I won't plan a mission around it.)

The Poodle is also unlocked quite a while before the NERV in career mode so it makes a good all-around space engine in the early-mid game. I used it to build my space stations around the Mun and Minmus, for instance.

I used to use it even more extensively but then I took a closer look at the Skipper and noticed that it has reasonably good vacuum ISP. I'd previously been using the Skipper exclusively as a lower-stage engine and staging to a Poodle for circularization, but now I've taken to using Skipper-based rocket SSTOs for lightweight payloads that can't fit inside a Mk3 cargo bay.

[GoSlash27]

11 hours ago, Tweeker said:

But seriously, what do you use the Poodle for?  In almost every case where you use a Poodle you can make the rocket better by swapping in a different engine.

Tweeker,
 You'd have to define "better". In stock career, "better" means lighter and cheaper. From 6 to 22 tonnes payload, 2km/sec DV, and .5 t/w (which covers the bulk of vacuum stage work in stock career), there is no better engine than the Poodle.

Best,
-Slashy

[Tweeker]

2 hours ago, GoSlash27 said:

Tweeker,
 You'd have to define "better". In stock career, "better" means lighter and cheaper. From 6 to 22 tonnes payload, 2km/sec DV, and .5 t/w (which covers the bulk of vacuum stage work in stock career), there is no better engine than the Poodle.

Best,
-Slashy

I mostly play career.

Well, for landers I define better as more delta/v,  shorter/ wider construction for stability, and  a  lower TWR to facilitate finer throttle adjustments on landing.

For transfer stages I define better as more Delta/v.for less weight I don't have a minimum TWR for transfer stages. The only reason you would worry about a higher TWR is impatience. The NERVA is often my choice in these stages. The engine costs more but it is cheaper to lift to orbit because the stage as a whole ends up being lighter,