phoenixr

Guess I'll plug my solution for outside loads. I call it an "outboard SSTO". Don't forget to use a fairing for unaerodynamic loads. https://kerbalx.com/tdqss/Outboard-SSTO-100t-noMJ

Around 900dV remaining - with the nukes of course - with a cargo a bit over 100t (3 full orange tanks). https://kerbalx.com/tdqss/Outboard-SSTO-100t-noMJ

Outboard cargo SSTO - album on imgur

Regarding your burnup issue: - Make sure the Science Junior is closed if you used it - it doesn't like heat and explodes very easily if it's open. Right click and Close. - Your return section is long and top heavy (the Mk1 capsule is quite heavy). This will cause it to tumble or invert completely. You can try to put some fins on the Mk1 to generate some aero drag and guide it so it comes down on it's own bottom first - where the heatshield is. This can cause some stability issues during your ascent, so you might want to put bigger fins on your boosters/lower stage to counter balance the aero drag on front that will want to invert your rocket. Airbrakes would be best because you can open them only for the return, but they are unlocked later in the techtree - Heatshield are not always necessary if you can make a gentle reentry - You can use another heat tolerant part too - engines for example or some aero caps (black parts are often more heat tolerant, but you can right click and check).

You're welcome . Sarcasm aside, you can save a lot of weight on your lander if it's not nuclear. You can look at some others' landers to get some idea of a working design. Some shameless self-promotion - my own first Duna lander mission: Nukes have low thrust and lots of weight, causing a low TWR, which is not very good for a lander - a low TWR will leave very little room for error. They even have a low ISP in atmosphere, so again not much sense in using them for a lander. Add some oxygen tanks to your tug and then you can even refuel a rocket lander for multiple landings. There is no best engine in KSP, each engine has it's niche. http://wiki.kerbalspaceprogram.com/wiki/Parts#Engines

Few more tips: Nuclear engines are HEAVY. They have a very nice ISP but if they need to move a lot of weight, the benefits start to fade. For your tug, the fewer engines you use, the better - but the burn will take a lot longer - so try to balance practicality. In your case, the 3 are probably still ok. But, your lander is also made with nukes? 4? Well that will make it very heavy, that's why you couldn't slow down. Plus the longer it takes to land, the longer your fuel is wasted fighting gravity's pull. A higher thrust and lower weight engine might be a better idea. If you still want to go with the nukes, consider adding some airbrakes toward the top of your lander - it will help you keep retrograde so you can burn for the landing, and also help slow you down. Parachutes alone are not enough for heavy landers - so you will need a rocket assisted landing. Also, you started your landing from a high orbit. You should start from a circular orbit just above the atmosphere (50km for Duna) and burn just a bit - get your Pe to ~40. This way you'll spend more time going sideways through the atmosphere, slowing down, before you reach the ground.

I think it's off topic here, but it's simple, just download the mod and extract it into the install folder. The Steam install folder might be a bit tricky to find at first, other than that just extract/copy to the correct folder. There are topics on it:

Yes, I think it was Interstellar Fuel Switch and maybe something else, it was a while ago. I used it as I only needed LF for the nuclear tug. Volume wise it's the same as a normal LF+O tank, just double LF and no O. It also uses Infernal Robotics - I planned to use the powered hinges on the nuclear nacelles to be able to turn them prograde/retrograde without turning the whole ship around - but I didn't actually use it at all. Yes, it's Steam.

Here is my single launch manned Mars Duna mission. Apollo inspired in that I had to put the lander right side up, then once in orbit separate and dock it back upside down. Uses an unmanned nuclear tug/fuel tank to get it to Duna orbit. I accidentally used an LF+O for the top cone section of the tank, so I decided to refuel the lander and attempt an Ike landing too. Just barely managed to get it up into a very low orbit before running out - Forgot to include a Mechjeb on the tug, so it took a good hour to get the sluggish tug to rescue them and dock. But it ended up getting so much science that it unlocked everything. (5821 research with one mission - http://steamcommunity.com/sharedfiles/filedetails/?id=518987386)