Spricigo

At 65km the atmosphere is very thin, so it will take a while to slow down enough. Also watching it from the tracking station will not work, the craft will be put on rail and the aeroforces not calculated, so you need to be there to watch it If there is risk of running out of electricity arm the parachutes (check if they are set to deploy when safe).

You have CoD in front of CoM. Your rocket want to fly tail first. The solution it's to move the CoM upward or the CoD rearward. My suggestions: change a Swivel for a Reliant get rid of the 2nd (-1,75t at launchpad), put only 4 basic fins at the bottom fuel tank, put the cabin on top of the pod (for stability at reentry), remove 2 hammers. Tilt the rocket 5° in the editor and use a Launch Stability Enhancer to hold it before launch. Launch it (unkerbaled) and let it go. Just stage when SRBs burn out. DONT TRY TO STEER IT. Depending on the result of the test flight you will adjust the initial tilt: Started to fall before reaching space? Tilt up (more vertical) Reached space but run out of fuel before orbit? Tilt down (more horizontal) Once you get the correct angle you may archive a 75x75km orbit with 200-300m/s for return. Edit: notice I didn't tested it myself, maybe it still flip (drag from exposed parts of the cabin). Also settings fuel priority so lower tanks empty first help to maintain the CoM forward.

You may always do the math yourself with the rocket equation

That would fit "too narrow" by my standards. Mostly because I'd rather take the performance hit during lift off than the increased reentry time. (As my posted craft shows) I still think it may not slow down enough, but will be happy if you prove me wrong.

+800kg, for a craft that small it may cut a lot of the deltaV budget. Post a picture and give us more detail, so we can try to diagnose what is wrong. maybe all you need its a few pointers in the right direction.

Physical warp can be 2x, 3x or 4x faster than normal time and unlike normal Time Warp you can use it in atmosphere or under acceleration, the physics, including control inputs, still apply(but since calculations are done at faster pace may cause some inaccuracies) . You activate it by pressing [MOD] +[.] to go faster and [MOD] +[.] to go slower. Edit: if we were trying to post all at the same time the result would be more spaced posts

Well, I tested. Going at 2km/s it exploded at 23km. Periapsis set at 20km from 80km orbit. Enough to convince me that a safe trajectory is very narrow if possible at all.

@Abastro the heatshield is not for heat tolerance, but for drag. For what it's worth one can put a aerodynamic nose cone and make it draggier then a Mk1 command pod topped by a parachute

That is no problem with this design. Just press space and it will steer itself in the right direction, no SAS or control input required. If anything be careful to not raise the apoapsis too much (the Reliant, chosen for being low tech, is more powerful than the rocket needs). It also is stable at reentry with command pod forward and SAS off.

@bewingI think the idea behind the heatshield is to shift the CoM away from the pod+parachute. It's not a idea I like, but under certain circumstances it works. @Aegolius13 stuff-inside-service-bay & crew cabin works fine for 2, 4, 6 and 8 passengers according to my experience. However it requires a bit higher tech, specially if one wants SAS available.

Shameless self promotion time: https://kerbalx.com/Spricigo/Orbiter-Zero Its actualy for 4 passengers, if you really want just 2 remove one crew cabin. AVOID LANDING ON SLOPES!!

Roughly speaking too high and you fry, too low and you crash. But every vessel will have different limits for too high and too low. For the craft you described, reentering with apoapsis 80km and periapsis around 20km should be a good ballpark. Since you are relying on drag to slow down, as soon you setup your trajectory release the fuel tanks and engines, the added mass is a disvantage. Edit: duh! Read as 1 pod for pilot +2 pods for passengers.As @FullMetalMachinist suggest, just add some draggy parts to make it slow quickier. It may be basic fins, a open service bay or even some radial atached part are usualy enough. And whille its not the most elegant design a crew cabin on top of the command pod work like a charm.

Well, having a use don't means having a good use. Maybe it only means you usually don't bring enough fuel while I usually bring too much.

Better yet, a good glider willl allow to land exactly at the target. Granted it takes a considerable amount of practice, to fly and to design.

There is lots of assumptions and aproximations. That is because usually there is no pratical way to know for sure(too many variables), so people use that assumptions and aproximations to get a rough idea and hope for the best. For a more precise result you will need to delve deeper in maths, probably use numerical analysis or/and calculus. Wich for KSP is usually too much trouble because you can just try and revert. And when you get a particular design that works the next try will likely be to improve it in some way.

I don't go as far as say they are necessary but for sure tutorial make a huge difference. Some people have advantage knowing how those things work in real life (a knowledge that translate well to the game) but for us, mortals, it saves a lot of headache. QFT: there's no substitute for experience.

IMHO that is why, in a tortuous way, it make sense. Ideally those tank should never been there to be left empty or to be filled with extra dead weight. So, ideally, one don't have space for more fuel than necessary. Off course you are correct for what probably its the actual (non-ideal) circumstance of a vessel that need to be moved as it is. By now may be difficult to remedy heavier than necessary fuel tanks. Also, there is the (slight) possibility to find a good use for this extra fuel at the destination and the whole question if the optimization its actually worth the trouble.

agreed! I did a few "difficult" things in KSP but what I value most its learning to design simple and practical vessels to specific tasks, Something likehttps://kerbalx.com/Spricigo/SL37D . I consider myself far from an expert but there is a true enjoyment when a design works smoothly.

You may design a mun lander and use alt+F12 to set orbit around the mun/minmus/whatever.

And it makes a lot of sense. Empity fuel tanks are deadweight anyway.

Why not just use alt+F12 to move your base to a better spot? Seems a lot more hassler-free than messing with game files.

Well, the purpose of the HG-5 its even more extensive than this. If you have a 2 of stronger relays in orbit of a planet/celestial bodies, the HG-5 fill most gaps left. The 'problem' its that if a stronger relay is available bringing those instead is trivially more difficult. And people being lazy*... *me included

You can probably land just fine with 1-2 Terrier engines. Thud and Spark and are good alternatives depending on lander weight, player skill and player style. Smaller engines allow for a more precise control of the velocity but it will require longer burns. I'm a time traveller

3 methods: Vertical drop: just kill all the horizontal velocity and then control the vertical velocity until touch down. Not much fuel efficient, you are doing a 90° turn instead of a smooth curve, but landing close to a target is easy. Then reverse gravity turn: tilt your lander just a bit up from retrograde and burn. Fuel efficient because the burn is mostly aligned with the direction of the movement, somewhat difficult to get the initial tilt right and somewhat easy to land close to a target. The constant descent: approaching in a horizontal trajectory start a retrograde burn, as you slow down turn the lander up just enough to maintain a constant vertical speed while reducing the horizontal speed. Fuel efficient because it prevent vertical speed to build up, difficult to land close to a target. All three methods can be done as a suicide burn, that is performing the burn in the last moment, at full throttle, cutting the engines just before touching down with velocity close to zero; all three method will benefit from a generous TWR. In practice its common to combine the different methods, either for difficulties in following a particular method or just convenience. (e.g starting with a constant descent, change to gravity turn above the target area, finalize with a vertical drop).

The same basic principles of smaller design applies, Its just a bigger scale. Try to make anything that need to be lifted from kerbin as aerodynamic stable as possible. Avoid weak joints. Design for a good balance of power and precision since you will probably need to trade one for another. The idea of transporting each module in a separate flight and assemble it at the destination make a lot of sense. You will break a big problem into several small problems. For more specific help we need more info. (what is required for the station? what is the technology available? how do you plan to delivery the modules?) Too late...we already judged you.