Lt_Duckweed

This album details some of the design and flight of an efficient cargo lifter: https://m.imgur.com/gallery/fTWS13F Though this is a cargo lifter, if the carried tank + docking ports was instead replaced with liquid fuel, it would have a smidge over 8000 dv. If I added a cockpit and mining equipment it would drop the overall delta v in orbit by about 1000, still leaving 7000 in orbit. Adding 2 nukes would drop it again to 5000. When it comes to the most extreme of craft, I have been able to get 11,000 m/s in orbit with pure liquid fuel by minmaxing to an extreme degree. 104 tons takeoff mass, 2 rapiers, 2 nukes. Big S strakes for wings (6:1 wet:dry vs big s wing 4:1) a kerbal in a payload bay, hundreds of the tiny mk0 tanks (they have a 11:1 wet:dry ratio vs the standard tanks 9:1) stuffed along with all the engines under a tiny fairing, etc.

The answers you get are going to very much depend on what you feel a "high" twr is. For me, a lko twr of .2 or higher is enough to count as "high". With this twr you can get up to about 8000m/s in orbit with a well optimized craft. If you double your nukes for a lko twr of about .4, you can still achieve something in the region of 6000m/s. This is for me quite the generous twr, and I would feel comfortable landing on anything duna or lighter. If you go up to .6 twr, you are edging close to the point at which nukes are no longer your best option, but you can still get something like 4500m/s It is worthwhile to note that these numbers do not account for passengers or isru. You would need to adjust the numbers down a bit in that case.

While it is certainly true that actual reuse like the op is talking about is nearly impossible without excessive levels of tedium, the economical argument for sstos is quite strong. A typical expendable rocket can expect to cost about 1000 funds per ton delivered to lko A cost optimized expendable rocket with srbs can expect to cost about 700 funds per ton to lko A cost optimized reusable rocket ssto can expect to cost about 300 funds per ton to lko A cost optimized reusable spaceplane ssto can expect to cost under 100 funds per ton to lko (I've gotten as low as 60 funds per ton)

Does this count?

I feel like both example payloads are too small. The smallest SSTO I fly is an orange tank lifter, with most of my designs clustered around 115-145 tons payload. I find that below 36 tons it's just not worth it to try and build to payload size as 36 tons of payload is already down at a 2+2 rapier/nerv config and going any lower runs into issues of either having way more trust than needed, or having to figure out how to balance the craft and still be able to deploy the payload easily when you have one of each engine.

Today I visited Kerbol in an SSTO and got the first (to my knowledge at least) Eva report from Kerbol's atmosphere:

Unfortunately I can't share the craft file, as that is reserved for Stratz's patreon. It would most definitely work on Duna thanks to the huge wing area and large number of props, (plus you could just directly zoom away on nerv power alone, it has right about 1 twr in rocket mode) except for the fact that it doesn't have wheels. You would need to land it vertically and then take off vertically, which would require very flat ground. As for eve, the nuke twr is far too low, so it wastes most of its fuel trying to get supersonic, then runs out well short of orbit. We haven't retested this craft in 1.9, but all my other Jool sstos broke so this one would too. If the goal is just to get to low Jool orbit from it's 0 altitude that is definitely still doable, the margins on that are way more forgiving than on this craft.

The only time I have seen the root part effect drag is when the root part is either a fairing or a cargo/payload bay. As long as your root part isn't one of those it's likely the issue is coming from somewhere else.

Third and final update of the night. By swapping my intake/liquid fuel storage setup from one precooler to a partially filled Mk0 tank and replacing two aerodynamic nosecones with circular intakes, and also getting rid of my roll control surfaces, I was able to trim another 215 kg off of the craft. Mass: 18,322 kg wet, 8,295 kg dry Lf/Ox mix: 10,000 kg full, 252.9‬ kg remaining in orbit Liquid fuel: 175 kg full, 23.8‬ kg remaining in orbit Dv left in orbit: 91 m/s

In a stunning turn of events, Mr Oneupsmanship 3 was revealed so quickly, that Mr Oneupsmansip 2 never even got a chance to launch. This craft improves on the original by shaving 1.2 tons of dry mass. Mass: 18,537 kg wet, 8,295 kg dry Lf/Ox mix: 10,000 kg full, 332.25 kg remaining in orbit Liquid fuel: 200 kg full, 39.65 kg remaining in orbit Dv left in orbit: 117 m/s Parts replaced/removed are: Mk1 Inline Cockpit + Aerodynamic Nosecone -> Mk1 Command Pod + Small Nosecone: 220 kg saved 2x Circular Intake -> 2x Aerodynamic Nosecone: 40 kg saved 2x Elevon 4 pitch surfaces -> 1x Elevon 4 pitch surface: 40 kg saved 2x Thud -> 1x Thud: 900 kg saved

Please give a warm welcome to "Mr. Oneupsmanship", which has been very deliberately positioned at exactly 25kg lighter than the currently lightest entry. Mass: 19,737 kg wet, 9,475 kg dry Lf/Ox mix: 10,000 kg full, 26.4 kg remaining in orbit Liquid fuel: 200 kg full, 4.55 kg remaining in orbit Dv left in orbit: 8 m/s

Metallic hydrogen would "decompress" the same way c4 would "decompress", by violently exploding. Metallic hydrogen is not a gas, it would be a liquid/solid, and it is in a metastable state, meaning when it decomposes into a gas it releases a LOT of energy.

That section of the guide hasn't been true for nearly 5 years now, but has never been updated. Things in a fairing or cargo bay do not produce any drag. Things not in a bay create drag based on the shape of the part, but if node attached to other parts, the surface area that is attached will no longer be counted.

Right about 134 tons when totally full. And yeah it took a lot of time to get the design refined, and we even ran the mission all the way up to the laythe landing before realizing the design didn't work for the water takeoff and had to adjust the design and start the mission over.

We used the largest fan blades, 48 of them in fact! As for part clipping... there are 200 of the little mk0 liquid fuel tanks crammed under the fairing along with plenty of other goodies!

So a while back @Stratzenblitz75 and I did a collab project where we flew a 2 Kerbal part clipped monster of an SSTO from Kerbin to Jool "surface" and back via refuel pitstops at Pol and Laythe. Looking through the challenge rules I think it qualifies. I wouldn't consider this an entry though, just want to show that it is possible (or at least was, props got nerfed in 1.9 so this craft would need a serious redesign)

@fourfa the reason you are seeing weird results is drag is not calculated off of nodes, but off of the surface area of a parts drag cube. When you node attach parts, the surface area of both parts that is in contact is subtracted from the drag cube. The important thing here is that the surface area does not necessarily match the node size. In the case of the rtg, it's node size is .625m, but the surface area associated with the node is less than a .625m cylinder, so when you attach it to a .625m fuel tank, the rtg end is covered completely, but the fuel tank end is NOT fully covered. An opposite example is the 1.25m reaction wheel. It has a 1.25m node, but it has a surface area that is larger than a 1.25m cylinder, so when placed inline with 1.25m fuel tanks, the fuel tank ends will be fully covered, but the larger surface area of the reaction wheel will NOT be fully covered.

I think my greatest regret with that video is that we went down to -249.6m instead of -249.9m lol.

This was definitely the most fun I've had in KSP so far!

If I didn't want people to use my craft I wouldn't have uploaded it . I've never personally downloaded any craft, but that's mostly because I get the most joy in the game out of building new crafts, so if I've got Kerbal open, I'm probably tinkering with a new design.

At hypersonic velocities, wings produce the optimum ratio of lift to drag with a positive angle of incidence of 5°. Any more or less than this will give you a worse lift to drag ratio. Your goal when flying an SSTO is to always have the fuselage as close to 0 angle of attack as possible, and have the wings as close to 5° as possible. This is an example of a drag optimized SSTO, and thanks to the 5° wing incidence it can get to orbit with no oxidizer. https://www.imgur.com/gallery/fTWS13F

As a matter of fact, I have used props in Jool's atmosphere! As far as I am aware, SSTO from Jool 0 altitude is currently one of the most exclusive clubs in the game, having been done by only 2 or 3 people.

Last post of the night, I promise. 1 juno pushing 4.249 tons to 539.4 m/s giving a score of 2291.9 points.

No bay shenanigans this time, what you see is what you get. And what you get is a fixed wing craft with 1 juno pushing 3.180 tons of craft to 632.2 m/s for a score of 2010 points.

I would like to submit my entry for supersonic fixed wing. 1 engine pushing 2.481 tons at 628.1m/s which gives it a score of 1558 points. If the fact that Jeb's head is peeking out a bit and the battery is overlapping with the rtg a tad are an issue, I can redo with slightly different placement.