Foxster

Depends on just where the lower TWR kicks in but it is usually "a good thing". You obviously need 1+ TWR to get off the ground vertically and having a decent head of steam gets you out of the thicker atmosphere quicker. Once you are into your gravity turn though then a lower TWR will indicate you aren't carrying too much heavy engine unnecessarily and you won't go so fast that you lose a lot of dV to drag losses or risk heatplosion. For Eve it can be essential to either have a lower TWR upper stage or throttle back a lot to avoid high drag losses and/or heatplosion.

Definitely don't need aerospikes but if you haven't fleshed out the tech tree then there might but some other bits that will make it harder to orbit without. If you can get to Eve orbit then why not do Gilly first and maybe Ike too. They are pretty easy in comparison and will really fill the tech tree if you do all the science you can.

Yup, been saying this for a while. The parts' images need a little graphic on them with their part size.

If your only aim is to return science and a crewman then there is nowhere that you can't make a direct re-entry from (without making orbit first) with a mk1 capsule and a heatshield with 20% ablator.

It is working as designed, the difference between the flow through decouplers and ducts is that ducts only flow one way, the direction of the arrow on the duct. Decouplers flow both ways. Crossfeed on decouplers is kinda OK if you have just drop tanks. If you have engines in the outer stack though (as in your example) then things can get messy. The outer tank with the higher priority gets used first but when empty the outer engines gets fed by the inner tank, which usually is not the desired behaviour as you'd want the outer engine to stop running and you'd stage that stack off. An enhancement request was made to be able to set the flow direction of de-couplers. In the meantime it's perhaps best to stick with ducts. As well as being one way, they do have the additional advantage of making fuel flow visually more obvious. When I have more time I'll try to answer some of your other questions.

I'm not sure how entirely unrealistic it is though. In the picture above, in reality the sharp back end of that nose cone would produce a lot of turbulence behind it and a fair amount of air would interact with the tanks. There'd be no clean cone of air protecting the tanks behind the nose cone from the effects of air flow, it would be more complex than that. I'd say it's a thing that is difficult to model in KSP. By this point though I think we should be further along than having air just flow straight through everything.

For places like Eve, airbrakes can be mercilessly exploited. As long as they are inside a cylinder behind the rim of a forward heatshield they are occluded from the effect of heat but are quite unoccluded as far as drag is concerned. This means they can be quite effective in producing lots of drag at the the back end whilst be immune to re-entry heat.

Trajectories is there but I thought that just shows in map view. Didn't think it could create a popup window like that.

Is this not widely known? Occlusion in KSP only works for heat and for adjacent joined parts. In other words, you can't reduce the drag of trailing parts by have a larger part out front. Similarly, draggy parts like airbrakes are always in the slipstream even with larger parts out front. "Also, entering a planet sideways as opposed to head on (with a lower surface area in the wind) most assuredly causes you to slow down faster." That's because you are presenting a lot of flat draggy faces of parts into the wind. If you go in head on, all the parts are still draggy, just a lot less so, even if visibly behind a large thing like a heatshield. This is the last big physics non-realistic effect in KSP that there seems to be no sign of being addressed.

I see what you mean. I guess though that the stabilising effect will not be right at the back, so you'll get a pivot effect.

Except in KSP, where the atmosphere blows straight through everything including heatshields. So your airbrakes work even though they are behind the heatshield.

From about 11 minutes...

I was watching a YouTube vid and the guy kept popping up a window in KSP that showed a kind of zoomed-out 3D view of his craft's path to orbit. A bit like map view in a pop-up window. Any ideas what it was?

Is it a balancing a pencil on your finger effect? There is a strong force on the leading edge of the craft and not so much at the rear end so it is inherently likely to tend to wobble at the back end. Adding LOTS more airbrakes to the back end usually fixes this for me. Oh and a continuous axial spin might help.

If you do want to stick with that big lower section then a couple of things to consider to reduce the drag losses A LOT... Use hardpoints rather decouplers. MUCH less massive and draggy than the big decouplers you used. Taper your stacks and make sure all parts, particularly engines in this case, match the size of what they are attached to. And where you have those three Vectors slapped onto the bottom of the centre stack...use an Engine Plate on the bottom of the tank, set Cluster Nodes for it to Triple and put the Vectors on its nodes... Of course, if you are sticking with that big lower stage then your upper stage is not great engine-wise. The lower bit will get you to 30km and you then want space engines (high vac isp) in the upper section. If you are going back to Kerbin then nukes might be a good idea.

Yup, mk1 capsules have 10 units of monoprob that you can get rid of with the slider. Also, it's worth knowing that if you do use a heatshield then almost always you'll never need more than 20% ablator no matter what speed you hit Kerbin at. Can save a chunk of dV from not carting around of ablator you'll never use.

In that case I don't think it needs the bottom half at all. If you: 1. Get rid of the heatshield and decoupler and the capsule's mono prop 2. Get rid of the ladders and have a lander can at the bottom of the craft to transfer crew from the top capsule in/out that you dump before liftoff 3. Get rid of everything below the upper Vector 4. Swap out the Decouplers for Small Hardpoints ...and you'll then have a craft quite capable of making Eve orbit...

OK. Got it now. Just checking...Is this just supposed to make Eve orbit or do you want to be able to fly back to Kerbin as well?

Still seeing the KER EngineerChip on the craft.

Just the orbit-capable lander.

The link worked but I don't use KER so can't load the craft in KSP. Could you take off the EngineerChip part and post that craft?

Nice job. Well done! I can see so many ways that could be optimised but the important thing is you made it. If you are interested in an optimised version then post the craft file and I'd be happy to make a few tweak.

Just for giggles, here's a nuke-upper-stage not-spaceplane that'll easily make Eve orbit from SL...

You can get to Eve orbit from SL with around 5500 dV (vac) if your craft is really, really low-drag and you make the best engine choices.

I think you are going to find the isp of SRBs just not good enough to get off the ground on Eve. One of the reasons for using either Vectors or Aerospikes is their high isp at ground level on Eve. SRBs though good enough on Kerbin just ain't gonna be up to it on Eve. I hope you prove me wrong.