AeroGav

Hmm. this isn't my finest creation.. https://www.dropbox.com/s/qyhybf8cvmj7qp5/Komet.craft?dl=0 I went for something scratch built for the challenge, but with 2 passenger cabins the Whiplash sits quite far back leaving me with a CG problem. I don't want to shove Jeb any further forward in case he cooks, so the NERVs have to go right up front. The deep chord of the Big S wings gets in the way, so i had the bright idea of turning stakes sideways to make a very early jet era looking high aspect ratio, mildly swept wing. Ended up adding too much fuel (26.5 ton wet mass) and it took 15 minutes to get to the point it was ready to start nukes, and at lower altitude it kept needing small course corrections, which was annoying. I used fine rotate tool to add some built in nose up tendency so you don't have to hold back stick to keep it in a climbing angle, but i overdid it this time which contributed to the sluggish flight (didn't get supersonic till 12km, whipslash not getting up on boost). For the speedrun, holding W down, but once we got over 1000 m/s it starts to climb anyway and lost power above 18km. Once the nukes are lit it does go like a champ though. Here's something i built yesterday, which i could enter instead since it carries 4 passengers. Actually it has 225 seats, but it's all liquid fuel, 6 panthers, 6 rapiers (air breathing mode only) and 12 nervs. It's actually a lot nicer to fly than the above craft, the panthers give it a solid initial climb/acceleration and it's really stable at all speeds, quite majestic. Action group 1 is nose up trim, action 2 is neutral trim, action 3 is nose down trim, action 4 is afterburner on/off, action 6 is nukes i think. https://www.dropbox.com/s/xmfebxxvbos8pt0/bigLL2.craft?dl=0

I last played with this about a year ago. It is much more realistic but though honestly the primary purpose of the challenge is to build stock lf sstos that anyone can use. The requirements to do so are not science fiction 1) TWR about 0.3 to 0.6 to 1 2) About a third of gross weight in fuel 3) A stable, controllable airplane. That said I'd be interested to see the Atomic age plane all the same. When I looked at the mod, it did not contain a mixed mode nuclear turbojet. So, you needed a nuclear reactor to power the nuclear turbojet for atmospheric flight, and a separate one to power your NERV rockets, which seems just about as crazy as the stock solution of burning Jet A to heat the combustion chamber of a jet engine while 3 tons of plutonium sit idle nearby. That said , those nuclear turbojets are fantastic for exploring Duna and Eve. For this challenge, just getting to orbit ? Not so much of a help. The additional weight of the nuclear turbojet over a stock jet engine , means you're not really saving anything by avoiding fuel burn.

Download the craft and examine it ? From memory though, no. If you're talking about the "tailplane" box structure, that's a modular wing panel attached to the Big S strake tail booms, and elevons are attached to the horizontal modular wing part as normal. Some of my larger designs have canards attached to other canards to get a big enough control surface - i think the "Andromeda" cargo ship has that. Bear in mind that when one canard moves, it does not affect the out that is attached to it, even though as an all-moving surface it looks like it should. Sp canard A attached to Canard B is then attached to fuselage, both will have max deflection of 25 degrees. You won't have B deflecting 25 degrees which affects the mounting hinge of canard A , causing a total deflection of 50 degrees when its actuator kicks in

Decided to graft the updated nose from the Chamical Monstrosity onto its NERV powered sibling - the mk1 inline cockpit recessed into cargo bay trick solves heat issues, but it does make the craft even longer. Surprisingly stable in flight, i think all the parts are cancelling each other's random torque vectors out making it fly straight. Lots of inertia though, as you'd expect. It really needs more than one reaction wheel. You can see out of the bubble canopy just fine in IVA view, but over the nose (and over the side) visibility is not great... when it's climbing to space you can't really see the horizon. Booster cushion perhaps? https://www.dropbox.com/s/xmfebxxvbos8pt0/bigLL2.craft?dl=0

While waiting for the next one, I built a few liquid fuellers. First up , I wanted to try to rocket approach and made this incredibly dangerous thing for incinerating and smashing Kerbals, though it does sometimes go to space. This is a two stage to orbit design, but those Panthers cost less than most lower stages and it has nearly 3000 delta V. The orbiter part of the vessel has 2 nervs and a rapier in air breathing mode .https://www.dropbox.com/s/2gk6lwksw603r6c/Lancer.craft?dl=0 Next, I decided to have a look at @adamgerd's only craft on KerbalX... since he'd flown my SSTO, I wanted to try one of his. It turns out, it's actually a supersonic transport. But, I reckoned it would be easy enough to make into one. My version here https://www.dropbox.com/s/5kgqqmmvklymycs/vagabond ssto.craft?dl=0 Original here https://kerbalx.com/adamgerd/SAPAF-0132-MK1-Vagabond-Tested

Due to work commitments, I missed the closing date for the Minmus Base challenge, but I had a play with some concepts anyway. The first was a Carousel type amusement ride. A bit primitive, just a poof of concept. I was also thinking of making the NERVs detachable and put a command seat and landing gear on them, for a nuclear motorbike. Probably not a good idea if your Kerbals are hoping to start a family in the future. Now, as to how to get this wonky Carousel into space, I decided to tow it - The carousel is made of wing parts, it just acts as a giant additional tailplane and isn't particularly horrendous to drag behind you. I'm not very good at calculating spaceplane delta V so this thing actually turned out way overbuilt. I designed it to decouple the whiplash boosters (and some empty tanks) on flameout, the remainder of the craft (liquid fuel only!) now has huge delta V. The Carousel isn't all that heavy. A little later.. Saucer separation, Enterprise-D style. On an actual mission i'd tow it all the way to Minmus of course. This was actually the maiden flight, it went better than i thought. It's a bit tricky judging balance for a craft like this - with the Carousel attached, acting as a huge tailplane, there is a danger the airplane will be excessively stable and not want to pitch up at all. OTOH with it gone, are things going to get flip happy? In the end, the only problem was when returning with the carousel detached - there is a rear shift in CG with low fuel state, and it's not stable. However I was able to land it by putting my remaining fuel in the forward tanks. Another iteration and i reckon i could eliminate that nasty characteristic, but i'm not sure i can find the motivation right now !

There's concern some people will struggle with this liquid fuel to orbit challenge, so i'll try to give some pointers if you want to go for a "Cruiser spaceplane" type solution 1. Use Mark 1 parts ! Mk2 parts have loads more drag, and will make this much harder 2. But what about heat ? Use an inline cockpit, and try to put the crewed bits 1 or 2 modules back from the front of the stack. eg. Shock cone intake at the front, service bay, then cockpit/crew cabin. 3. Try to keep all your fuel in big S strakes and wing parts, they have the lowest drag per unit of fuel stored. Yes, cylindrical tanks have slightly lower mass, but that gets lost in the mass of those heavy NERVs. Also , wing parts make LIFT and you'll want all the lift you can get. If your design needs more fuel, clip some extra strakes on and fill em up. Of course, if you need a trim tank at the front or back of your craft and don't want wings there because that'd mess with your Centre of Lift, by all means drop a cylindrical tank in. 4. Similarly, you ideally want all your lift surfaces to be big S ones that do double duty as fuel tanks, but in practice you may need to add small modular wing parts at the front or back to fine tune your CoL, and you might not also want to add fuel in the same location, so do what you need to do to get it flying straight and true ! 5. One jet engine per 20 to 30 tons of takeoff weight. At the upper end of this range it gets harder to accelerate and the flight takes longer, at the lower end you are more likely to have fuel issues. 6. One nuke per 10 to 15 tons of takeoff weight. 7. To reach orbit comfortably, you want 25 to 33% of your craft's total weight to be fuel. Suggested mods - 1. RCS build aid - make 's it really easy to see where your CoM will be when the fuel burns off, and if your engines are out of line with centre of mass and likely to cause pitch up or down torque 2. CorrectCoL - makes the blue centre of lift indicator more accurate 3. Kerbal Wind Tunnel - shows how much excess power your craft has at each speed and altitude, shows you where it's easiest to bust the sound barrier One thing i still struggle with is centre of mass/craft layout. Nukes are really heavy and you can't shove your crew cabins too far forward to balance them or you'll roast in the re-entry heat. So you want to put the nukes as far forward as possible, but at the same time the efflux needs to not impinge on the wings or other surfaces ... and you can't mount them too far above or below the centreline of your craft or you get unwanted torque. Over to you guys, lets see some creative designs..

You managed to get my SSTO orbit and land it though...

The OP You can tell quite a bit from his screenshot - the airplane is at about 5 degree angle of attack (difference between prograde and where the nose is pitched up), the closer you are to stall the bigger this gets. The G meter is only showing 1g, so his AoA is not the result of a harsh maneuver, that's just from straight and level flight. I imagine that if he gets much slower than 70 m/s he'd be at >10 degrees angle of attack , at which point most designs would be at risk of tailstrike, and an outright stall at 60 or less. For a utility airplane that's not great, most of my space planes would be under 50 m/s at 5 degree alpha.

Those basic swept wings have half the lift rating of the other wing parts of same mass, your takeoff and landing speeds look rather high in the screenshot.

Each to their own.. I can build a basic small crew SSTO in half an hour, most of the time is lost on stillborn designs that never leave the hangar. I can't get CoM sufficiently far forward, the whole concept is beyond saving - start over. If I get as far as the "Launch Vessel" button I can tell whether this will make orbit or needs more tweaks before we've reached 100m. I take off, turn off SAS and see if the nose starts veering off prograde. If it pitches up more than a couple of degrees, it's gonna be a pig even if i can fight it to orbit, back to the hangar for you. Pass that test? Throttle up and down, does the nose rise and fall with thrust - then i didn't pay enough attention to RCS build aid, back to the hangar ! Finally, i yank full back stick and try to stall it. My first orbit in this game was with an SSTO. I had been trying to build rockets too, but it took a few more days before i could make one that didn't flip. Whilst i do have successes, there's usually a dozen reverts while i work out how to gravity turn each design. As for rovers... let's just say if i had to get to the tracking centre, i'd build an airplane, take off and fly to it, then land next to it. I've never built a rover that got more than halfway across the space centre without flipping and blowing up. Wheel physics in this game are just horrific.. or i just don't understand cars. BTW, let's not antagonize @kerbalstar any further and keep discussion about potential challenges to the discord channel :-) https://discordapp.com/channels/493195034154500098/494608257588002847

I would not disqualify that nerv /rapier rocket of yours.. it should be allowed for its ingenuity. I was arguing against the person who wanted to make it a caveman ssto challenge instead, which would specifically ban the use of NERVs or advanced jet engines. Not that there's anything wrong with caveman ssto challenges but it should be a different challenge altogether. My challenge suggestion is liquid fuel to orbit, by whatever means. Going the airplane route, on a trimotor design you can either build a zoomer, with 2 jets and 1 nerv, get into a steep climb at 1000 m/s plus then hope to buy yourself sufficient time to accelerate to orbital velocity before falling back into the atmosphere, or a "cruiser" like my example "Sparrow" design with 1 jet and 2 nervs, that does 1000 m/s in horizontal flight, then lights the nukes and hopes to be able to continue accelerating on the power of 2 nervs while making sufficient lift to support itself with its wings.Taking the zoomer philosophy to its logical conclusion you end up with the craft you make - and it is perfectly within the rules of that challenge - but i cannot offer any advice on that craft type as i have never built or flown one. Taking the "cruiser" approach to its logical conclusion -

People are building submarines for Laythe, jumping rovers from Gilly to Eve and landing fairground attractions on Minmus ! I consider all of those things really hard ! I'll include some tips for my challenge though, if it gets picked. Really I think so long as you can build a stable, moderately efficient airplane you're in with a shout.Ps. Did yours look anything like this ?

My reasons are I want to raise awareness of the possibility of building a craft this way. When you look on KerbalX, every SSTO out there is a RAPIER ship , practically all of them only have sufficient flying qualities to get to mach 4 or so at altitude then at that point they fly as a rocket , with TWR well over 1. Using NERVs as your only rocket engine means TWR well below unity. which means your craft needs to be able to fly like an airplane in the upper atmosphere, actually make lift with its wings, and have more lift than drag. If you can pull this off you get a useful interplanetary SSTO. There have been loads of low tech SSTO challenges but start another one by all means. Every career mode game becomes like this anyway... but the trouble is these low tech SSTOs aren't actually all that useful once tech in the Tier 8 node is available. Please keep the two challenges separate. Another caveman SSTO challenge will not develop the skillsets (aerodynamics in the upper atmosphere) i am wanting to encourage.

i've been doing some optimization of the Chemical fuelled Monstrosity, got rid of the Goliaths for a mix of Panthers and Whiplash. These can hit a solid 1200 m/s without using the Rhino, and suddenly I found myself getting to orbit with about a third of the oxidizer unused. So i remove one pair of orange tanks, and still get to orbit with almost a third left... and so on. Six iterations later, we've halved our rocket fuel tankage. It's now got a TWR of 1.0 at the start of the Rhino burn and of course that only goes up as fuel burns off. Perhaps this is simply the ideal TWR for a chem spaceplane (been a while since i built many) or perhaps the Rhino is simply too much engine for 14 mk3 cabins. So I either got to go even bigger , or convert to RAPIER . https://www.dropbox.com/s/22awnt4mz6dy26i/Rhino Goliath3.craft?dl=0 Dry Mass 213T (up from 175, must be extra jet engines) Wet Mass 304T (OX capacity greatly reduced) Fuel Fraction 42%

I tend to obsess over efficiency, building SSTOs with svelte mk1 fuselages, big S wing strakes, no oxidizer, and clipping drag-reducing cones into everything. But what if you need something BIG ?? What about part counts ? Surely now is the time to ditch the silly little NERV engines and install a honking big Rhino ! This engine really is a beast - in terms of vacuum/high altitude ISP it is up there with the best, and better TWR than any other Vacuum engine. Heck, this thing runs the Raptor and Mammoth close. Jet engines ? Well my initial thoughts were to go Goliath, since that's the largest jet available and keeps part count low. Sure , it has a low top speed, but all this really needs to do is get us to an altitude where the Rhino can do what Rhinos do. After an unsuccessful test flight, I compromised on a config of 4 Goliaths and 4 Whiplashes. Here is the beast - Takeoff Weight 417T Fuel Mass 242T Dry Mass 175T Fuel Fraction 58% Parts 92 For comparison's sake, i then tried to make a liquid fuel only version of this craft, with the same mk3 cockpit and 14 passenger cabins. I'd never gone this big, and had doubts the approach would work on something so large. I was also worried the part count would melt my pc, so it had to be Big S wings instead of strakes (they hold less fuel for their size) and I had to refrain from my usual trick of putting cones on the back of engines. Nukes were attached with Type B tail connectors, which are heavier than NCS adapters, larger, draggier, and don't hold fuel, but save 1 part since you don't need a small nose cone on the front of them. I swapped the Rhino for a mk3 engine mount, put a tri coupler on the 2.5m node, for a total of 6 panthers. Six RAPIERS are attached to the side of the fuselage amidships (economy cabin will be a noisy place). Twelve nukes are bolted on, I had to redesign the tail and reposition the landing gear to clear the efflux. The wing is enlarged significantly. Surprisingly, dry mass is unchanged at 175T. Takeoff weight is greatly reduced, since our fuel mass is now only 53T. Fuel Fraction is 23%. Both vessels squeak into low orbit with about 150m/s remaining. Part count has gone up to 124, about a third. It was surprisingly well behaved, with a less frightening takeoff (more wing, more engines less weight ) and less prone to mid air breakup (those huge fuel tanks aren't trying to snap us in half). Perhaps I didn't do a very good job on the chem ship - anybody want to make a better showcase for pure chemical 14 cabs to orbit ? What is the largest you can go LF? Rhino Goliath - https://www.dropbox.com/s/1uxskn61qadq4d1/Rhino Goliath.craft?dl=0 Nuclear Disaster - https://www.dropbox.com/s/zpp5q2z04r66hgh/Nuclear Disaster.craft?dl=0 ag 1 pitch trim up ag 2 neutral trim ag 3 trim nose down (note check orientation of trim flaps before flight, the deflection directions get messed up when you edit the craft) ag 4 panther afterburner ag 6 toggle nukes

I 've now had limited success with this thing. It generates enough downforce with its wings to force itself below the surface, i was 50m down at one point. It does well on the going to orbit part too, would probably send Val to Minmus. Where the design fails is that it can't land in the sea, at least not when fuelled up - things always break off, and it is no longer spaceworthy. I had to land on the beach and drive into the water. Also, as a boat it is horrible. Pitch stability goes negative if you pitch down too much, overwhelms the controls and sends it into bunt. Then it floats to the surface on its back and can't be righted. The design decision to mount the wings low is probably to blame. With the fuel mass all being down there, the engines are above CoM and there is a huge pitch down torque, if you gun the throttle before it's got some water speed, it does its swap ends trick. Also, it is more stable floating inverted, with the heavy engines under the light wings. Perhaps if i add sharp dihedral i can get the inboard wing to be the first thing to touch the water, without screwing my CoM so much.

I did write something more recent than Mark Thrimm's guide in the Tutorial section, guide to building mk2 space planes, though really my advice is "don't build a mk 2 !" since that is the draggiest fuselage type and creates a lot of problems. If you're building a liquid fuel only mk1 ship, some tips - 1. Use inline cockpits and crew parts, don't put the crew parts at the very front of the stack, have some intakes, service bays or inline dock ports to absorb re-entry heat. 2. keep all your fuel in big S wings and strakes. Try to avoid fitting any traditional fuel tanks at all, if possible. Remember, strakes orientated vertically make good vertical stabilizers which also store fuel. 3. One jet engine per 30 tons. You can go as low as 20 or high as 40, but 30 is good point to aim at . 4, Two nukes for every 30 tons. Again, you can go as low as 20 or high as 40. 5, Fuel fraction ? 20% of you gross mass as fuel is actually enough to make orbit. 25% makes orbit comfortably,. If a third of your mass is fuel, you can start to think about landing on Minmus. 50% is the upper limit, diminishing returns are biting hard and your payload fraction will be very small here. These fuel fractions are much less than you'd see in a chemical ship,. Don't forget my speed build video for a practical example of all this (in my first post in this topic, but here it is again - https://youtu.be/3uY5nZ3jL5I ) ..and the craft file here if you want to see how it flies - https://www.dropbox.com/s/zsw71d2g9qqc7d7/sPARROW.craft?dl=0

Always fun to fly each other's craft, it's the only multiplayer element the game has really :-) Please let us know how you got on with these craft and any variants you created ! I must admit I sometimes forget how most people use SSTOs when i build mine - mine are intended to do a lot of exploring themselves, with NERV engines, interplanetary delta V and the ability to land offworld. They're not really designed to be easy to dock to space stations etc. That would require an extensive RCS system and docking port in the nose, which would add a lot of drag and make the NERV/Liquid fuel approach less viable. Mine have reaction wheels and inline docking ports, but are best flown up to the vicinity of the other vessel and then get docked to by some space tug that doesn't have to worry about aerodynamics. Top off the tanks, and on they go further into the Kerbol system..

Good to see you've had success. The Whiplash engine hits peak thrust at mach 3 (about 900 m/s) and declines to about half that by mach 4.5. Rapier Peaks at Mach 3.7 and is still giving 80% of peak power at mach 4.5, then it quickly falls off the boil. The Whiplash's altitude characteristics are also less good. Speedrun altitude on Whiplashes is about 17km vs 21km for RAPIER. I'd have thought you should be able to get close to 1100 m/s on Whiplash , was that in level flight? Once the Aerospikes kick on, I'd say just maintain a pitch angle such that the nose is not more than 5 degrees above Prograde, as drag builds rapidly after that. As you can see I'm a fan of combining RAPIERs and Panthers, but the differences aren't that large i suppose. Also Whiplash make blue flames which look cool. Oh yes, the good old days of fretting over how much oxidizer to bring. Not enough, won't make orbit. Too much, it becomes dead weight for the NERVs to drag around. I think that's one reason why I nearly always go pure LF these days. One fuel gauge, you've either got gas or you haven't, simples. So, looks like you got - 4 nerv (12t), 8 darts (8t) and 12 Whips (22t) - for a total engine mass just under 42t. I'd probably swap the mounts to triples and try with 6 nerv, 6 rapier, 6 panther , for a total engine mass of 36t. Rotate the Rapier mount 90 degree sideways so the inboard motor is inline with CoM and the outers are above and below, then set an action group so you can switch the inboard to close cycle while the outers stay AB, or vice cersa. If you want to share the craft file i'll have a play with it. As you can see, with SSTOs efficiency seems to trump "moar boosters", though i did attempt to build something different today and just "go big", trying to get as many Kerbals in orbit as possible while keeping part count down. So, the rocket engine is a Rhino our jets are Goliaths. Actually that wasn't enough jet, so i stuck on 4 whiplashes (wasn't going to be easy finding space for another pair of Goliaths). OVer 400 tons gross, more than half of it fuel (despite the apparently small size of the tanks compared to fuselage), I had to deal with unfamiliar problems, namely wings snapping off due to insufficient strutting.

Nothing ready made that fits those requirements - they are pretty specific. Perhaps you can get help with converting an airplane to a seaplane ? I've only built two, going the hydrofoil approach. I manage to take off from water with TWR of 0.7, but perhaps better hydrofoil design can get than down - or just use plain floats? On LAythe of course, with less gravity, perhaps it is easier. https://kerbalx.com/AeroGav/Puffin ...the Kerlew hasn't flown in recent KSP - https://kerbalx.com/AeroGav/K133--Curlew The trouble with hydrofoils is that there is no info in the editor about lift and drag in water, it is pure trial and error.

In answer to your original question, the Pre-Cooler is outstanding at low speed and good enough at high speed to feed a single RAPIER all the way to mach 6. The Shock Cone is outstanding at high speed (one can feed many) and ok at low speed (enough for one engine). A combo of a single shock cone and single pre cooler could feed 6-8 engines across the speed range i'd bet. However, i always find i've got enough 1.25m nodes to cap off at the front that I'm running more intakes per engine than that. Intake drag is pretty minor compared to fuselage drag now. Re: Your ship 1. The best LF/Oxidizer tanks on a capacity/drag basis are the 2.5m ones. Mk2 tanks are the worst, swap them all for Rockomax tanks then see if you can get away with less engines - exchange the quad mounts for triples. 2. Engines are heavy. RAPIERS 2 tons each, they are hurting your Delta V massively. A reasonably slick ship should be able to do fine with 30 tons per jet engine. Or, try one panther and one RAPIER per 50-60 tons. The hard bit is getting past mach 1. The Panthers can help there and are very light, by the time they quit at mach 3, the RAPIERs will be going ramjet mode crazy. If you can bust mach 1 you can bust 1400 m/s in level flight at 21km. More RAPIERs than that doesn't get much more air breathing speed as their thrust falls off rapidly after mach 4.5, it just kills your delta V with dry mass. 3. If you can angle your wings up where they attach the fuselage, you can make sufficient lift with the airplane flying on prograde hold. This keeps the fuselage angle to the airflow minimal and really cuts down on drag, which means less engines still. 4. Wings that don't have fuel in them are a waste. I only use non fuel wing parts if i need to change the position of CoL without adding fuel to that part of the ship. As for how efficient you can go, well, i did build this, which can orbit an orange tank. The minimalist fuselage makes little drag on prograde, but the wings still make plenty of lift, so it doesn't need oxidizer and can get to space with the feeble thrust of a few nervs. Those nervs in turn, sip fuel and get all they need from the wing tanks. https://kerbalx.com/AeroGav/Andromeda That said, cargo bays add huge drag and have quite a bit of mass even when empty. This thing will never be as efficient as a dedicated crew/science mk1 fuselage explorer ship.

For a career save, there is the limitation that my craft mostly use top tech parts. I hope that's ok. But these are all stock and they don't bite, though I have had issues with the "pitch trim" action groups i use to try enable people to fly without a joystick and prograde hold only. Often, the trim changing flaps randomly swap to deploying in the wrong direction, and nose up becomes nose down etc. Do a control check before liftoff or if you're a joystick user, feel free to ignore all that. https://kerbalx.com/AeroGav/MK1-Griffon-Deep-Space-Crew-Shuttle 40 tons, 11 seats, inline clamp o tron, 3k delta v left in LKO. Uses Rapier and Nukes and big S wing parts , so a high tech ship. If you're thinking of refuelling it in orbit and sending it to Laythe or Duna, I recommend attaching small landing gears to the trailing edge of each wing as outriggers, you are more likely to get an airplane you can use again afterward. https://kerbalx.com/AeroGav/Puffin 3 Seat Seaplane SSTO. Can take off from water with enough delta V to reach Minmus. Was built for the lake landing challenge and it currently has very weak landing gear, needs beefing up. Also could use some kind of docking port, but needs a solution that doesn't add drag. Would be nice to have for Laythe I reckon. https://kerbalx.com/AeroGav/Andromeda Cargo SSTO. https://kerbalx.com/AeroGav/Learstar-A2 Interesting concept perhaps, not full SSTO but has panther boosters on the wingtips. Low launch cost, far less than a shuttle, better delta V, easier to fly IMHO. Finally, a couple of lower tech offerings. https://kerbalx.com/AeroGav/Krakenskimmer-Mandalay-class-SSTO 3 Kerbals to Minmus with 2 nukes, 1 Terrier, 2 Panthers. Val likes it. If you have nukes and whiplash and Big S parts but not yet Rapier, there's this thing i put together in a huge rush - https://www.dropbox.com/s/zsw71d2g9qqc7d7/sPARROW.craft?dl=0 @adamgerd got it to space with more delta V than I managed and even managed to land it (i've not tried) so it can't be that bad despite being a rush job. Or @adamgerd is some combination of Ice Man, Maverick and Luke Skywalker all rolled into one, be very afraid.

I already spent a few hours trying a few things, the problem is i've never made a submarine before and its hard. I've made a couple of seaplanes that can go to Minmus, it's not that hard once you can hydrofoil. The problem with subs is that practically everything floats. After crash landing my seaplane, i was surprised to discover that NERVs float. Guess that explains why life rafts all say "penalty for improper use , £300", they are made of Uranium and improper use violates non proliferation treaties. Liquid fuel and oxidizer tanks float too. Xenon sinks, but i'm not too sure about building a Xenon/Jet SSTO, unless i incorporate a load of wings and batteries, which float really well. https://kerbalx.com/AeroGav/Puffin

The biggest factor in heat tolerance is how far back the crewed part is in the stack. Thus, your mk3 shuttle cockpit is basically right at the front of the ship (the nose cone only covers a small part of its area) so is much more prone to overheating than a mk1 inline cockpit that's a few parts back in the stack . I haven't really explored the limits, preferring to play it safe, but my mk1 inline cockpit ships are ok for direct descent from an AP of 350km or less. From Minmus, I prefer to do a few aerobraking passes with PE not lower than 45km for the initial pass. Depending on how hot things got, i may lower PE further on subsequent passes. Duna is not too much different, but Jool is a challenge to say the least. For aerobraking, holding radial out is fine, but i'm not a fan of using that for the final re-entry or below 45km altitude where aero forces are getting strong. A plane that's aerodynamically stable will be fighting the RCS hard to bring its nose down, the plane will seesaw wildly with oscillations in pitch, roll and yaw, and you'll waste huge amounts of electrical power and monoprop that you might be needing later. If your plane has negative stability when empty, it will flip and go backwards. Radial out deep into the atmosphere is only possible if you got really strong RCS and a perfectly neutral airplane that is neither stable nor unstable, something that would pull off awesome aerobatic manuvers lower down. The other problem with high angle of attack for the final re-entry is that you're giving up control over where the plane comes down. You can't predict how long the tumbling will last, even if you hold perfect radial out you can't increase or decrease rate of descent. If heat is an issue i prefer using 20 degree AoA on final re-entry, since that gives almost max lift (keeping you out of the lower atmosphere till slow as possible), and also high drag. If you're not in dire straits, i prefer to enter with 10 degree AoA, and watch your trajectory on the blue line in the map mode screen. If you look like falling short , lower the nose a bit so you're closer to optimum glide angle (5 degree aoa when above mach 1) . If I'm overshooting, I pitch up above 10 degrees, since high AoA adds more drag than lift. I usually retro burn to ground level in the desert continent west of the space centre, if your craft is reasonably aerodynamic you'll find the blue line moves steadily downrange as you encounter the atmosphere , since the blue line is calculated for wingless capsule re-entry vessels, so you'll need to pitch up and increase drag to prevent overshoots. I did an old youtube video demonstrating this - it has annotations explaining all this, but i don't know if your player is still able to show them (they don't work on smartphones, for sure) Of course, this thing has the same size wings as your shuttle on a much smaller fuselage, so it glides a lot more..