Filling gaps in Stock Parts (cooler name pending)

[problemecium]

Over my time playing Kerbal Space Program and participating in the community, I've repeatedly either felt a need for a part that seems like it should be available in the stock game or caught wind of recurring requests for one part or another to be added, so I finally sat down and listed them all out. They're not in any particular order but are sorted into categories for parts I think are most important to add, parts that maybe aren't so essential but that I at least would find nice, and additions specific to the DLC packages. Many of these parts are already provided via one mod or another, but to obtain all of them would require downloading many different mods, creating issues with compatibility, game balance, and having tons of extra parts that change the game beyond the scope of filling in gaps in the stock parts. Having extra new parts isn't something I'm saying is bad - it's just not the goal here.

What I'd like to discuss in this thread includes others nominating parts that the game really seems like it was supposed to have, but more importantly whether I should try to assemble a pack out of existing mod parts (and navigate redistribution permissions) or recreate those that exist (and create afresh the few that don't) and who else is interested in helping, largely as I'm vaguely okay but not that good at 3D modeling or texturing (evidence: my old Jump Drive mod) - certainly not up to par with those who made the game's newer part models. I essentially see this as a collaborative community project, though if it turns out I'm the only one who wants these or can't find useful common ground, I accept the risk of having to try to do it all myself or give up on the whole thing.

If the curators of mods that contain these parts are interested, feel free to nominate your own parts for inclusion in this hypothetical pack. This is not a vanity opportunity and in all likelihood parts that don't closely match the stock look, scale, and functionality won't be included as-is, if at all, but if you do have a good fit, perhaps we can combine our work into a holistic one-stop package.

Important:

Spoiler

Linear Aerospike: There is a toroidal aerospike, but nothing good for making VentureStar and X-33 replicas.
Size 2 LV-N: The LV-N is wonderful, but propelling a large interplanetary mothership with it requires either an abysmal TWR or an unholy part count. A double-sized LV-N with quadruple the thrust would be very useful and as I recall is often requested, provided by stand-alone mods, or a motivation to download the Interstellar or Near-Future mod packs.
Size 2 Liquid Fuel tank: For some reason, liquid fuel tanks come in Size 0, Size 1, Mk2, and Mk3, but Size 2 only provides liquid fuel and oxidizer combinations. Mk3 is very similar to Size 3 in cross-section, but Mk2 is not a good substitute for Size 2, particularly as its capacity is on par with Size 1. The increased collision tolerance is nice for aircraft but irrelevant for nuclear motherships.
Long Size 0 Tanks: Size 1 and larger fuel tanks come in short and long varieties and some in between, but in Size 0 the only cylindrical tank is the Oscar-B, meaning that providing large amounts of fuel in narrow cross-sections requires unnecessarily large part counts. I find Tylo landers a recurring victim of this problem. This and the previous item usually seem to be addressed via TweakScale, Procedural Parts, or a fuel switch mod.
Tiny Probe Core: The "Ant" engine seems intended for propelling very small objects similar to a CubeSat, but there is no probe core appropriate for constructing such a thing. The closest matches are the Probodobodyne OKTO2 and QBE, but both are much larger than the "Ant" engine. The game seems like it could use either a rescale of the QBE or an even smaller core, no larger than the Not-Rockomax Micronode.
Heavy Strut: The strut connector is a very useful part but has intentional limits on its maximum length and a specific breaking strength and visible size. It seems as though there were supposed to be other sizes of strut at some point. A smaller strut would only have niche uses, but a thicker, stronger strut able to reach further would be useful in launch towers, large payload assemblies, motherships, etc. This could even have a fancier visual model with a truss; I prototyped one a while back but I haven't opened it in a while to see if it still works in the game and my modeling skills have never been great.
Falcon Leg: The SpaceX Falcon 9 features a very large landing leg, and I often see people replicating it or landing ships of a similar scale and having to make do with much smaller legs or constructing larger legs using DLC parts or ...abominations. The game provides pretty much everything else (see next item) to replicate a Falcon 9 replica and the community is in general very invested in SpaceX's exploits, making the absence of such a part seem strange.
Grid Fin: The one other thing missing from the Falcon 9 is the grid fin used for attitude control on return. Replicas, as in the previous bullet, have had to make do with mod parts or the very small (for this purpose) air brake parts. A larger air brake might fulfill this purpose, but the grid fin's ability to manage roll in addition to pitch and yaw would remain unaddressed.
Tiny Rover Wheel: The smallest rover wheel remains too large for very small craft such as the Sojourner rover. Kerbals should be able to build something reminiscent of a shopping cart.
Tiny Leg: The smallest useful landers, i.e. probes or single-Kerbal lander can shuttles, can easily pack into Mk2 cargo bays but have a lot of trouble fitting unless either the legs are clipped (and clipping moving parts seems silly and is very unrealistic) or they use weird substitute legs such as RCS ports or antennae (or go without entirely and are forced to land very carefully).
Big Truss: The modular girder segment is good for medium-sized truss assemblies, and the octagonal and cubic strut pieces are useful for very small ones, but to replicate something like the ISS is made more difficult for lack of a wide, heavy-duty truss segment. Ideally this would come in both square and octagonal cross sections.
XXL Solar Panel: The Gigantor XL solar panel seems like it was intended for ISS replicas, but next to the other station parts, it's too small. It remains useful for various probe and satellite replicas with large but not huge panels, but there is no panel large enough to match those on the ISS and replicas have to use mod parts or large sets of Gigantors that only match vaguely.
Deployable Relay Antennae: "Standard" antennae can be toggled on and off, and packed up to stow for launch or re-entry, but the existing relay antenna parts don't replicate this functionality. The ability to shut off a relay would also have its uses, at least for testing antenna ranges and verifying relay coverage.
Big Klaw: The addition of a small Advanced Grabbing Unit is very nice, but there should also be a large version useful for actually grappling and moving large asteroids and comets. Surely the developers knew we'd start trying to do comet redirect missions...
Tiny Winglet: Creating very small aircraft (such as drones) is difficult without having to clip moving winglets (ew). Even the smallest winglet in the game completely dwarfs small components such as the Size 0 nose cone and the small probe cores and fuel tanks.
Size 2 RAPIER: The Skylon spaceplane uses large engines that, relative to the crew cabin and other parts, strike me as a better match for Size 2 than Size 1. Add to that the number of very large spaceplanes people build that use arrays of dozens of RAPIERs. Alternately the RAPIER could simply be re-worked to have a single engine bell such that Skylon replicas could use an array of four to recreate the real ship's four bells.
Small Lab: The Mobile Lab is configured as if meant to work alongside various other possible sizes of labs with varying science return ratios, data capacities, and crew capacities. The most salient that seems to be missing is a single-Kerbal lab, perhaps with a Size 1 cross section, though the case could be made for a Mk2 lab as well. A lab that isn't tall relative to its width would also be conducive to surface bases or mobile lab rovers.
Size 1 and 3 Multi-Couplers: The Size 2 multi-couplers are useful for making engine clusters with engines that don't allow surface attachment, but no such part is available to attach Size 0 engines to a Size 1 ship or Size 2 engines to a Size 3 ship.
Single Crew Cabin: There isn't a compact module to serve the purpose of providing an extra (internal) seat for a Kerbal. The seeming best match is the lander can, but it can't fit inside a Mk2 cargo bay, and the Mk1 Pod is needlessly heavy for this purpose, not to mention pretty cramped inside.
Short / Fighter Cockpit, or perhaps Surface-attachable Cockpit: The Mk1 Cockpit is nice for "civilian" aircraft, but many of us (I believe, anyway) miss the old fighter-style cockpit and lack an option to recreate it without a mod, plus the existing cockpit is very long, making compact stowable aircraft difficult. Alternately one or more cockpits could be made that can stick onto the sides of other parts, something I imagine would be popular in place of clipping cockpits into fuel tanks on large rovers, motherships, etc.
Tiny MonoPropellant Tank: The DLC does provide a small roundified tank, but there is neither a cylindrical counterpart nor an even smaller tank for tiny probes that don't need a full 20 units and are hampered by the weight of the larger tanks. The command pods provide small amounts, often between 7.5 and 15 units, but there is no stand-alone tank able to do this.
Surface Hatch: Sometimes making a good spaceship happens to involve covering up hatches, or it involves putting a crew cabin at one end of the ship and then wanting to disembark on the other end. People also like to replicate buildings or other structures that have doors and use a Mk1 lander can clipped into a wall as a substitute. More elegant would be a stand-alone airlock part that can be attached to the surface of another part to provide an extra EVA hatch. In the interest of consistent game mechanics, this might require the part to have capacity for one Kerbal and thus it might be better off serving as the single-occupancy cabin mentioned above.
Large Surface Parachute: Surface-mount parachutes are very useful for recovering spent booster stages, but their small size means that often a LOT of them need to be used. There is a large stack-mounted parachute and drogue chute. On this topic, perhaps a small stack-mounted drogue chute would be useful too, but it's a lower priority due to the already small size and mass of the surface-mounted drogue chute.
Dragon / Starship Leg: SpaceX's Crew Dragon and Starship crew stage use linear extending landing legs, but the stock game includes no linear leg of any kind. The DLC provide pistons, but these are only a very rough match for this purpose. Honestly I'd like a rework of all of the landing legs, standardizing them and allowing each to come in at least a linear and hinge variant if not also a linear/hinge mix as we have now.

Optional:

Spoiler

Nuclear reactor: Something to provide power far from the Sun, or at night, like the RTG, but which is much more powerful, would be very nice, mainly for long-range ion probes but also on large motherships that go through a lot of energy with their reaction wheels and take forever to recharge via existing methods. This could be very heavy and expensive, and naturally come very late in the tech tree, to preserve game balance. RTGs would remain the system of choice for small craft such as New Horizons or even Cassini-Huygens replicas.
Rosetta harpoon: The Rosetta mission's Philae lander didn't use a klaw but rather a set of harpoons to snag the asteroid and reel itself in. Not only would such a part add fidelity to replica missions, but it might be useful for rescuing Kerbals or assisting in docking unwieldy (or fuel-deprived) objects.
Small/surface cupola: The cupola module is very nice, and the weight reduction in newer editions of the game is helpful, but it is quite large and heavy for what it is. On the ISS, cupola modules are relatively small and are attached to the sides of "main" modules to serve as fancier windows. Since there is, nevertheless, an existing cupola module, this is a low priority.
Round fuel tanks: spacecraft, or at least concepts, for example the Daedalus, feature fuel tanks shaped like geodesic spheres. Since interstellar exploration isn't addressed in the stock game and there are no other parts appropriate to the Daedalus or similar ships, this might not be that essential. Naturally the actual in-game part would be much, much smaller, but I don't know any small-scale missions that feature these off-hand, even though it seems like a thing they would have. There is a small gold tank, but I'm talking about larger tanks similar in scale to the FL-T, Rockomax, and Kerbodyne series.
Vernor cluster: MonoPropellant RCS ports come in linear and block versions, so the lack of a block version for Vernor engines seems weird, but it can be substituted easily enough with groups of Vernor engines.
Round solar panel: Several modern spacecraft concepts feature circular solar panels, so the emphasis in recent years on collaborating with real space agencies to help players replicate their missions suggests this should be a thing.

DLC-specific:

Spoiler

Orange skin for size 4 tanks: fairly self-explanatory. The five-meter cross section seems more proportional IMO for Space Shuttle replicas and for SLS replicas that use the larger boosters, but making a five-meter tank orange isn't an available option for some reason.
Size 2 rotor: making large artificial gravity rings that aren't really wobbly would be easier with an extra-large rotor.

 

[GuessingEveryDay]

I know that Near Future has plenty of various sizes of solar panels. However, I know that Luciole has some “CubeSats”, but these don’t include any fuel.

 

[EchoLima]

Great idea! Here are some suggestions I have for parts:

Stock

Short Size 1 tank 

Small Omnidirectional antenna that doesn't need to be extended

Midtier 1.25m engine 

Midsize solar panel (maybe based off the OX-STAT-XL)

Inline parachute

1.25m abort tower

DLC

1.8275m habitat module 

Soyuz style capsule?

Surface attachable weather experiment?

 

Edited July 8, 2020 by EchoLima

[Aerodinamic Potatoe]

realistic science ezperiments,solar panels,radiators(because why not)AAAAAAAAAND MORE ENGINES AND FUEL TANKS

[Tonka Crash]

3.75m and 5m capsule, lander can and passenger cabins.  There are lots of mods for "small" parts but not nearly as many for larger sizes with high crew capacities. I want landers on the scale of 2001's Aries 1B with a capacity of a couple dozen tourists.

Edited July 10, 2020 by Tonka Crash

[Dux Aquila]

On 7/8/2020 at 3:44 PM, problemecium said:

Surface Hatch: Sometimes making a good spaceship happens to involve covering up hatches, or it involves putting a crew cabin at one end of the ship and then wanting to disembark on the other end. People also like to replicate buildings or other structures that have doors and use a Mk1 lander can clipped into a wall as a substitute. More elegant would be a stand-alone airlock part that can be attached to the surface of another part to provide an extra EVA hatch. In the interest of consistent game mechanics, this might require the part to have capacity for one Kerbal and thus it might be better off serving as the single-occupancy cabin mentioned above.

For me this part is the most important, how many parts there are with a door but can not be used because it is not a hatch! A transparent part to place in front of the aforementioned parts would be ideal