What is the least useful non-structural part?

[I_Killed_Jeb]

Useful for ultra light landers (with the seat).

they also look cool

[ComradeGoat]

they also look cool

I've used a couple of them under a seat on a Mün rover, to get the driver back to orbit when he's finished roving. Light and low profile. They're great!

[Spatzimaus]

The Delta-Deluxe winglet. I haven't found a time when it is more useful than the standard canard.

The delta-deluxe has three key advantages over a canard:

1> Lift. It's got the same lift rating (0.7) as the standard canard, for only half the weight. This makes them great as parts of horizontal wings, with the extra control surface being an incidental advantage over stock wing components. It also makes them good choices for tails.

2> Oversteering. A canard has a tendency to make your vessel wobble, although this isn't as bad as it used to be. The delta-deluxe doesn't do this because its control surface area is smaller.

3> Attachment. A canard has a long baseline where it attaches to the vessel, which can make it hard to fit. The delta winglet has far less trouble with this.

My personal spaceplane uses 18 of the things instead of mounting canards; they're very, very good when used right. Here's a picture:

[CaptainArchmage]

Definitely the Inline Advanced Stabilizer module in the current version. The ASAS functionality isn't really needed anymore since it is found on the command pods and normal reaction wheels, and it has a mass of 0.5 tons as opposed to 0.3 tons on the Inline Reaction Wheel. The Advanced S.A.S. Module, Large, however, has a mass of only 0.2 tons for some reason, so it is quite useful.

[makinyashikino]

this useless piece of ...tech... has never been used by my space agency. The much hated LV-1 Liguid fuel engine. 1.5 thrust almost no thrust and a pain in the ass to mount non radial.

I like it for satellites, I mean the radial is easier to mount, but this looks better in my opinion if there is a unused in-line surface.

[I_Killed_Jeb]

I've used a couple of them under a seat on a Mün rover, to get the driver back to orbit when he's finished roving. Light and low profile. They're great!

oo that's a brilliant idea

[Moar Boosters]

The big blue parachute is kinda redundant. It doesn't do anything the radial one doesn't, but weighs more, seems to have a weaker connection point, and has limited mounting options.

[Spatzimaus]

The big blue parachute is kinda redundant. It doesn't do anything the radial one doesn't, but weighs more

Parachute braking power scales with its mass. So while both are listed as having 1/500 drag values, the blue one has twice as much braking power due to its larger mass.

[Nimaci]

I'd have to say the Mainsail and Skipper, because LV-T30/45 cluster.

Oh and all wings/aero-control surfaces, I have absolutely no use for them.

[panfish5]

Yep, I'll vote for this one as well. Although I did use it once in career mode to get just the amount of TWR I needed. But that's only once during the thousands of rockets I've build.

I actually quite like using those on my landers because they don't really get in the of landing legs and are quite aesthetically pleasing.

[Themohawkninja]

I'd have to say the Mainsail and Skipper, because LV-T30/45 cluster.

Oh and all wings/aero-control surfaces, I have absolutely no use for them.

I thought the advantage for the cluster was quite minimal?

[numerobis]

Engine nacelle.

Nose cones.

Most of the control pieces (which are there for historical reasons).

Most of the probe bodies.

An ant can fly Jeb from LKO to a soft landing on the Mun, and return (better have a parachute though). You'll use a couple Round-8 tanks for it.

The delta-deluxe has the second-best lift:mass ratio; the small control surface is best, but your plane is going to be hard to land if you use that as your only wings.

I personally have never found use for the Mark-55 either. Too heavy, too much competition.

[Galileo Kerbonaut]

I actually quite like using those on my landers because they don't really get in the of landing legs and are quite aesthetically pleasing.

You use those for landers!? (<---Rockomax MK55) WOW... that's an awful lot of thrust power you got there. On landers I usually use these: (Rockomax 24/77)

[numerobis]

I thought the advantage for the cluster was quite minimal?

The mainsail is useful for part count. Otherwise, a cluster of 50 48-7S engines provides the same thrust, less mass, better Isp -- but that's 99 parts. For long burns (~3km/s) such as Kerbin's surface to upper atmosphere, the T30/T45 cluster is better. Where the T30/T45 combo really wins is in more frequent staging: you can maintain a more constant acceleration, rather than having to drastically undershoot and then overshoot your thrust requirement with a mainsail.

2 T30 and a T45 is same mass, almost same thrust, better Isp than the Skipper. That, or 22 48-7S engines get you almost same thrust, same Isp, for just over half the mass. In the other direction, one mainsail is 2t less mass than two skippers for quite a bit more thrust, so you can add a lot of fuel to pay for the Isp difference.

Edited December 17, 2013 by numerobis

[Themohawkninja]

The mainsail is useful for part count. Otherwise, a cluster of 50 48-7S engines provides the same thrust, less mass, better Isp -- but that's 99 parts. For long burns (~3km/s) such as Kerbin's surface to upper atmosphere, the T30/T45 cluster is better. Where the T30/T45 combo really wins is in more frequent staging: you can maintain a more constant acceleration, rather than having to drastically undershoot and then overshoot your thrust requirement with a mainsail.

2 T30 and a T45 is same mass, almost same thrust, better Isp than the Skipper. That, or 22 48-7S engines get you almost same thrust, same Isp, for just over half the mass. In the other direction, one mainsail is 2t less mass than two skippers for quite a bit more thrust, so you can add a lot of fuel to pay for the Isp difference.

The cluster only really works for first stages though, as you can't nicely stack them without having to put more parts on in the form of struts as the cluster is more bulky (which also makes the cluster less useful for radially attached booster stages).

[Giggleplex777]

This.

It's so ugly!

[Stargate525]

This.

*snip*

It's so ugly!

I have found through this thread that the least useful parts I have actually BLOCKED from my memory as if they were a trauma.

Seriously, I hadn't the faintest inkling that this or the toroidal even EXISTED before I saw them again in here.

[FlamedSteak]

On landers I usually use these: (Rockomax 24/77)

These are also nifty if you need a pinch of additional thrust. Their ISP is terrible though.

[panfish5]

You use those for landers!? (<---Rockomax MK55) WOW... that's an awful lot of thrust power you got there. On landers I usually use these: (Rockomax 24/77)

It kinda depends on what planet you are landing though. I also dont have good memories with those rockomax and I think the look little terds hanging off the side of your ship .

[Levelord]

This:

Useless TWR, abysmal ISP and all round crappyness.

[FlamedSteak]

This.

It's so ugly!

I hate all those parts.....everytime I tried to build something with the mk3 cockpit it's ended up looking like it's been pieced together with left over bits from a NASA junkyard.

[UmbralRaptor]

Too many parts on the command, aerodynamic, and utility tabs are tempting (eg: the Probodyne QBE, OKTO, Engine nacelle, covered solar panels...)

[Spatzimaus]

(eg: the Probodyne QBE, OKTO, Engine nacelle, covered solar panels...)

The QBE and OKTO aren't as light as the OKTO2, but they provide plenty of spots to attach all those science-y bits you want to use on your probes. For an ion probe, that space can be a major consideration. (Although strangely, you left the HECS off your list, and that's the one I use the most for my probes.)

The covered solar panels are a strange case. Yes, they mass 40% more than their "naked" counterparts, with identical statistics otherwise. And the streamlining doesn't actually matter at present, given the primitive drag model. But they look nice, and some day we'll have a FAR-type aerodynamics model in stock KSP where their shape actually matters. I use them on my spaceplane, despite the weight increase, simply because aesthetics matter to me.

I'll give you the nacelle, though. Although an even more useless choice would be the Radial Engine Body, since it doesn't even function as an intake.

To the original question, my votes would be for the circular intake (almost purely inferior to the Ram Air Intake) and the Basic Jet Engine (almost purely inferior to the Turbojet Engine). I've yet to see a situation where you'd want to use either of these in lieu of its high-altitude alternative.

[Lazro]

Nosecones are at this point completely useless outside of FAR. All they do is close off a node and add weight. Most parts do have some use ( you can build rockets with the mark 55, the engine nacelle does provide intake air, structural parts allow for stronger construction and radial engines) but the nosecones are completely useless.

[numerobis]

The circular intake looks better than the bulky ram intake, but other than that, there's very little reason to prefer it. This differs from the radial, which is useful at low speed.

The basic jet is far more efficient on liftoff: it has 150 kN thrust rather than 112.5 kN, 2000 Isp rather than 400 (taking into account half thrust), and is slightly lighter to boot. If you're cruising below 5km you can't do better. We just don't usually spend much time down near the surface.