If I ever make it back from Eve

[Laie]

@herbal space program same here with regards to explodyness. Even if you mount a deflated heatshild for a nosecone (haven't tried, only thought of that just now), I think the solution is a lower TWR somewhere and the willingness to climb to higher altitudes.

Put differently, one stage has to shut down while still at a safe speed and going up quickly; the next one may (must?) start at a relatively low TWR so your airspeed doesn't doesn't outpace whatever is safe, while your momentum carries you upwards into thinner air. IIRC my last one (above) reached orbital velocity at 60km, so fairings are certainly capable of withstanding that much. No idea how much more resistant a heatshield would be, or if the drag is worth it.

[Foxster]

I find it's a matter of really dropping the throttle from ~15km until the final stage kicks in, which has much lower TWR. Down to around 15% so that rate of climb is constant or falling a bit. Otherwise the high TWR of the lower stage that was important to get above the worst of the souposphere quickly becomes a liability by too high an acceleration generating too much heat. 

That's for a single engine small craft though. Not sure if that scales up with a bigger craft and more stages. 

Edited February 22, 2019 by Foxster

[herbal space program]

5 hours ago, Laie said:

@herbal space program same here with regards to explodyness. Even if you mount a deflated heatshild for a nosecone (haven't tried, only thought of that just now), I think the solution is a lower TWR somewhere and the willingness to climb to higher altitudes..... No idea how much more resistant a heatshield would be, or if the drag is worth it.

That got me thinking.  If I really want to put my boosters where my mouth is, maybe the best thing for me to build would be the most tightly packed core of bundled tanks possible that fits under an inflated 10m shield, with just enough wiggle room to avoid incineration due to small deviations from prograde. The lower, soupy phase of the ascent could be done with the shield deflated, but at the altitude where heating becomes a big problem and drag is much less of one, I could inflate it and keep boosting away at high TWR until I reach orbit. Staging would all be vertical, so the rocket is skinny down low and stubbier up high. I might just have to give that a try...

[Reinhart Mk.1]

yeah this is pretty tough, as ill-advised as it sounds i think i'm gonna make a ssto and orbit eve and send a small lander

yeah im gonna try that

[Laie]

22 hours ago, Foxster said:

I suggest taking this out of this thread now as we are off-topic. If you want to continue, which I'd be very happy to do, then please post something new in Challenges. 

Still designing lifter, but even if successful I'm no longer sure of what the take-away lesson would be. That the best nosecone wins, or that larger lifters have more freedom in when to stage, and what engines to use? Neither is exactly news.

Something I find interesting is that my previous lifter got down to 5.5km/s using a much lower TWR and (presumably) steeper ascent profile than you did. IMO that warrants investigation, but I have no idea how to phrase a challenge for that.

18 hours ago, Foxster said:

Otherwise the high TWR of the lower stage that was important to get above the worst of the souposphere quickly becomes a liability by too high an acceleration generating too much heat. 

Yes, that's what I'm talking about. Seems as if ferocious acceleration at takeoff isn't strictly necessary.

 

Edited February 23, 2019 by Laie

[GRS]

6 hours ago, Reinhart Mk.1 said:

I'm gonna make a ssto and orbit eve and send a small lander.

Be grateful of what you're capable of doing, i'm still garbage in SSTO Spaceplanes.

[herbal space program]

7 hours ago, Laie said:

Yes, that's what I'm talking about. Seems as if ferocious acceleration at takeoff isn't strictly necessary.

I don't think it's really helpful to carry that kind of TWR all the way up, but in those first few seconds I think that getting to near TV as quickly as possible does make a real difference.  My biggest problem right now is that I'm having a very hard time initiating my gravity turn so that I can stay locked to prograde all the way. For me it seems like a matter of 1-2 seconds between starting too early and burning up and starting too late and hitting my 90km Ap still pitched to 45 degrees. Any deviation from dead prograde to try to correct it during that phase is prohibitively costly in terms of drag, so it seems like you just have to hit it perfectly.

[Reinhart Mk.1]

1 hour ago, herbal space program said:

I don't think it's really helpful to carry that kind of TWR all the way up

LOL speaking of which this small im working is so small and fast it will actually explode from overheating if it's not at least at 90 degrees on take off, i really need to learn how to orbit without a backup nuke engine though. i always need it for the last like 95% of the... stretch, journey? idk but yeah i thought that was cool

[Reinhart Mk.1]

well since it kinda seemed to help last time i kept the fairing, but i added two more heatshields. not sure if it'll help at all but the design looks kinda cool, like a trident lol. also the twinboar i had on the bottom didn't seem like it would do much help even i managed to land it so i went with the old design, a more popular type of eve lander. delta v looks good, this is the last burn until i break the atmosphere

Edited February 23, 2019 by Reinhart Mk.1

[GRS]

Will Advanced Nose cones give me better Aerodynamics than the basic ones ??? (Like enough for very low altitude ascent, i dont wanna rely on MJ)

Edited February 25, 2019 by GRS

[herbal space program]

So it looks like this whole Eve Lifter dV optimization conversation is going to get its own challenge, thanks to @Laie, but since strict lowest vacuum dV-to-orbit  looks like It won't be a category and I spent a lot of time on this, I thought I'd post it here as my final entry for that criterion:

 

This is my best ascent so far for this 650-ton, 5m-cored lifter. The part that gets to LEO weighs just over 29t. All engines are Vectors,  one for the upper stage, 12 mounted on engine plates under the big tank, and 24 more on the short-burning side stacks. The smaller fairing at the front has a 2.5m heat shield behind it, and is expected to explode sacrificially on the most optimal profile, but it actually didn't on my best run so far, as can be seen by the still-intact base on the orbiting upper stage. The side stacks boosted me to 300 m/s, roughly TV for that ship, in the first 12 seconds, and from there I remained locked to prograde at full throttle from my initial ~10 degree inclination until around 20 km, where I was just south of 45 degrees. I then slowly lowered throttle until I was essentially coasting at 25km. to an AP of around 50, slowly pitching down, and opened it up again around 45km.

Anyhow, total vacuum dV expended from SL to LEO: 5,258 m/s (now 5,202 on latest attempt), flown without any kind of autopilot assistance. I'm sure I can still do better than that even without an autopilot, but as it is I think this proves that large tanks are in no way inherently worse than smaller ones for this sort of thing. But we can perhaps continue that discussion in a new venue...

 

Edited February 25, 2019 by herbal space program

[herbal space program]

19 minutes ago, GRS said:

Will Advanced Nose cones give me better Aerodynamics than the basic ones ??? (Like enough for very low altitude ascent, i dont wanna rely on MJ)

I don't have any special insight into the code, but in my experience pointier is generally better. I have seen people use intakes as well though, because their drag is calculated differently. Really pointy fairings are what seems to work the very best for me.

[Reinhart Mk.1]

well my last design ended up getting around 20k but didn't come close to orbiting, current lander is parachuting to the surface. good lord this has been hard

[Reinhart Mk.1]

I just have to vent here but there is something obviously wrong with my game, either that or this is  a bug but this has been happening on EVERY single attempt i've tried. I cannot EVER save during a stable descent with parachutes toward eve without the save being cursed. every time i load my ship explodes. i wasn't doing any top gun stuff, nothing out of the ordinary on my ship. safe.stable.slow.descent. i literally have to re-enter the atmosphere and start from there (which isn't necessarily BAD but what's the point of saves if they dont work in stable environments). This is a giant chunk of my frustration with this planet.

[herbal space program]

6 minutes ago, Reinhart Mk.1 said:

I just have to vent here but there is something obviously wrong with my game, either that or this is  a bug but this has been happening on EVERY single attempt i've tried. I cannot EVER save during a stable descent with parachutes toward eve without the save being cursed. every time i load my ship explodes. i wasn't doing any top gun stuff, nothing out of the ordinary on my ship. safe.stable.slow.descent. i literally have to re-enter the atmosphere and start from there (which isn't necessarily BAD but what's the point of saves if they dont work in stable environments). This is a giant chunk of my frustration with this planet.

Welcome to Eve! Yeah, I pretty much never try to quicksave when I'm in any kind of highly dynamic situation, because that's what usually happens. It happens on Kerbin too if you're pushing the structural limits of an airframe, like if you save at Mach 2 and 3 km om a spaceplane ascent. But on Eve it's baked in! 

Edited February 25, 2019 by herbal space program

[Reinhart Mk.1]

so

saving on eve=

25 minutes ago, herbal space program said:

like if you save at Mach 2 and 3 km om a spaceplane ascent

[GRS]

2 hours ago, Reinhart Mk.1 said:

I just have to vent here but there is something obviously wrong with my game, either that or this is  a bug but this has been happening on EVERY single attempt i've tried. I cannot EVER save during a stable descent with parachutes toward eve without the save being cursed. every time i load my ship explodes. i wasn't doing any top gun stuff, nothing out of the ordinary on my ship. safe.stable.slow.descent. i literally have to re-enter the atmosphere and start from there (which isn't necessarily BAD but what's the point of saves if they dont work in stable environments). This is a giant chunk of my frustration with this planet.

Well...it happenned on me when first doing my Eve Centurion, and since that's the only quicksave i got, i'll have to start from scratch,(i mean the flight) you were either too close to surface, or opened too many chutes, my Eve Centurion can't remain intact below 1 Kilometer if i opened all of its Parachutes, so i opened the radial mount chutes and leave the larger ones closed until Touchdown, a good point to quicksave is when you're capable of releasing Drogue Chutes.

Edited February 25, 2019 by GRS

[Reinhart Mk.1]

17 minutes ago, GRS said:

a good point to quicksave is when you're capable of releasing Drogue Chutes.

thank you! that seems like a good sweet spot

[GRS]

Oh, and try keeping liftoff TWR around 1.2-1.5, except Launch Kicks, you'll need that so you won't be Accelerating too quickly (if you don't want to rely in MechJeb)

Edited February 25, 2019 by GRS

[Reinhart Mk.1]

new design, i'm the most confident with this one. as long as i get the staging/throttle down

[Reinhart Mk.1]

GOT HALF WAY INTO ORBIT, need one more stage and i swear i can get this thing to work

[herbal space program]

5 hours ago, Reinhart Mk.1 said:

GOT HALF WAY INTO ORBIT, need one more stage and i swear i can get this thing to work

I'm happy to take a look at it and see what advice I can offer if you're getting fed up, but I don't want to spoil it for you either 

[Reinhart Mk.1]

36 minutes ago, herbal space program said:

I'm happy to take a look at it and see what advice I can offer if you're getting fed up, but I don't want to spoil it for you either

ignored the golden rule of moar boosters, i can't really be blamed. eve really is a s#!t show

also i dont really wanna spoil anything either (even though the design is basic and not really original) but

[herbal space program]

53 minutes ago, Reinhart Mk.1 said:

ignored the golden rule of moar boosters, i can't really be blamed. eve really is a s#!t show

also i dont really wanna spoil anything either (even though the design is basic and not really original) but

 

All depends on what you're trying to launch! One little bit of advice I can give you is that flipping that aft heat shield is a good idea, even though it's a pain to construct it that way in the VAB, because it's very aerodynamically unstable the other way, i.e. it will try to flip you even though it's behind you. Otherwise that looks like a good re-entry package to me (from what little I can see !). 

Edited February 26, 2019 by herbal space program

[Reinhart Mk.1]

1 hour ago, herbal space program said:

flipping that aft heat shield

I'll try that this one last time but after that im done, i am woefully unprepared even in my most prepared stage