If I ever make it back from Eve

[Laie]

3 hours ago, Foxster said:

I suggest a payload of a mk1 command pod to 105km +/-2 circular Eve orbit from HE coords Lat -0.423, Lon -59.859. Stock parts and physics. Craft file and video to be posted. Autopilot fine with me.

Well, lifting a single pod doesn't exactly justify a wide stack, does it?

I've just managed to make orbit for 5.5km/s(vac) from your starting position (200m high, boo!) -- using a 2.5m stack and quad vectors mounted to a Making History thrust plate. Payload was a Mk2pod and 15 tons of ore.

I didn't bother with building a rocket that has exactly the required amount of dV, I just took off with 6km/s and subtracted what was left. No special drag-avoidance shenanigans, and even a few struts and actual fuel lines just to spite you.

Video upload will have to wait until tomorrow, though -- if you're even interested, considering this isn't a stock vessel or your proposed payload. Besides, it's not yet quite as good as it needs to be.

BTW, may I propose lat 0.785, lon 107.93? It's a little closer to sea level.

Edited February 21, 2019 by Laie

[Reinhart Mk.1]

before i slumped to bed, frustrated at another failure to reach eve's surface and back I put my newest design in low eve orbit, time to buckle up

[herbal space program]

1 hour ago, Laie said:

I've just managed to make orbit for 5.5km/s(vac) from your starting position (200m high, boo!) -- using a 2.5m stack and quad vectors mounted to a Making History thrust plate. Payload was a Mk2pod and 15 tons of ore.

I didn't bother with building a rocket that has exactly the required amount of dV, I just took off with 6km/s and subtracted what was left. No special drag-avoidance shenanigans, and even a few struts and actual fuel lines just to spite you.

Video upload will have to wait until tomorrow, though -- if you're even interested, considering this isn't a stock vessel or your proposed payload. Besides, it's not yet quite as good as it needs to be.

BTW, may I propose lat 0.785, lon 107.93? It's a little closer to sea level.

Now that's what I'm talking about! I think maybe the point of contention here is about Pure Stock vs. MH. In Pure Stock, there really isn't any good way to put enough boom behind those massive tanks to allow them to have the same TWR for a tall, skinny rocket as for a tall, skinny 1.25m stack with a single Vector. But with those nifty engine plates and that 5m Saturn V multi-adapter available, that's no longer a barrier.  Based on your result, I would predict that a 5m rocket with the same shape and TWR could do even better, and I mean to see if that's the case, although you've set quite a benchmark there!

[herbal space program]

4 hours ago, Foxster said:

I suggest a payload of a mk1 command pod to 105km +/-2 circular Eve orbit from HE coords Lat -0.423, Lon -59.859. Stock parts and physics. Craft file and video to be posted. Autopilot fine with me. Lowest launch dV wins. 

(I think that what you are not really taking into account is that larger craft need more, bigger and draggier engines, couplings, nosecones, etc. They will all add up and eliminate any theoretical advantage of bigger tanks).  

How about you can make your rocket any way you like so long as you use only Stock/MH parts and you're not doing tricksy drag-and-heat-avoidance exploits like upside-down, clipped-in fairings? Also, any stable orbit should be acceptable, as should any takeoff site that is under say 150m. Why does it have to be so exact? The question we're trying to answer here is if you don't cheat the drag model, are wider or narrower tanks better for making the lowest-dV ascent possible from Eve? You and a few others insist that only the narrowest tanks are competitive, even though in RL physics it is most definitely the other way around, as explained by @Starhawk above, because drag scales as the square of linear dimension while mass scales as the cube. If you look at the equation for the Reynolds number on Wikipedia, you'll see that the term for linear dimension is on the top, implying that inertial vs. viscous forces in a given fluid will predominate more and more as objects get bigger, i.e. the more massive your rocket is for a given shape, the less it will feel drag. If it didn't actually work that way in KSP, then our aerodynamic model would be no better than what we had pre-1.0. Anyway, I'm interested to see what you can come up with at 1.25m that will beat the equivalent 5m rocket in terms of shape and TWR.

[Foxster]

2 hours ago, Laie said:

...just to spite you...

Steady. No need to get all riled up. It's just a game  

When you say its not stock, do you mean stock+MH? If so, craft file?

[Reinhart Mk.1]

okay while you all talk amongst yourselves i'm happy to update that other than the puny rhino (compared to eve) not being able to bring this beast in slow enough, i've put the vectors back on so here we go. take idk 849

[Reinhart Mk.1]

KERBAL SPACE CENTER

OUR CHUTES ARE OPERATIONAL

https://imgur.com/a/pX2VnVH

[I_Killed_Jeb]

4 hours ago, herbal space program said:

Now that's what I'm talking about! I think maybe the point of contention here is about Pure Stock vs. MH. In Pure Stock, there really isn't any good way to put enough boom behind those massive tanks to allow them to have the same TWR for a tall, skinny rocket as for a tall, skinny 1.25m stack with a single Vector.

Are people now longer in favor of the OG trick of using the small cubic struts as mounting points? Or does it do something wonky w the aero?

[Reinhart Mk.1]

16 minutes ago, I_Killed_Jeb said:

Now that's what I'm talking about! I think maybe the point of contention here is about Pure Stock vs. MH. In Pure Stock, there really isn't any good way to put enough boom behind those massive tanks to allow them to have the same TWR for a tall, skinny rocket as for a tall, skinny 1.25m stack with a single Vector.

oh dang this is awkward

 

16 minutes ago, I_Killed_Jeb said:

OG trick of using the small cubic struts as mounting points?

even more awkward now...

[I_Killed_Jeb]

7 minutes ago, Reinhart Mk.1 said:

oh dang this is awkward

 

even more awkward now...

uh.. what?

[herbal space program]

9 minutes ago, Reinhart Mk.1 said:

oh dang this is awkward

 

even more awkward now...

Awkward? This is pretty typical banter for this forum in my experience. You've just gotten a bunch of people who think they know what they're doing jettisoning some liquid fuel about it. I'm sure it will all be settled quite civilly.

[I_Killed_Jeb]

5 minutes ago, herbal space program said:

Awkward? This is pretty typical banter for this forum in my experience. You've just gotten a bunch of people who think they know what they're doing jettisoning some liquid fuel about it. I'm sure it will all be settled quite civilly.

I think the OP is best served by focusing on his Eve landing and less on stirring up non-existent drama on the forums.

 

That being said, cubic struts, is that not a thing anymore?

[herbal space program]

17 minutes ago, I_Killed_Jeb said:

I think the OP is best served by focusing on his Eve landing and less on stirring up non-existent drama on the forums.

 

That being said, cubic struts, is that not a thing anymore?

IDK, way back in the day they used to be ignored by the physics engine entirely, so you could make all sorts of exploitative craft out of them. Not sure how they behave now. And the inevitable debate among self-styled experts aside, I think OP has received plenty of helpful advice on this thread. And this is also an interesting question!

Edited February 22, 2019 by herbal space program

[Reinhart Mk.1]

35 minutes ago, I_Killed_Jeb said:

I think the OP is best served by focusing on his Eve landing and less on stirring up non-existent drama on the forums.

lol noooo im not trying to start drama at all, i meant that i used the cubic struts to attach multiple engines on the (i forget the name) biggest possible fuel tanks

also i was reading the comment about that maybe not being the best approach so maybe my lander won't work

 

but yeah no drama, im chill as a cucumber

[herbal space program]

32 minutes ago, Reinhart Mk.1 said:

also i was reading the comment about that maybe not being the best approach so maybe my lander won't work

Naah, this debate (at least the one I'm engaged in) is all about the edge of the envelope. You should mostly ignore all that for your own purposes and just try to create the most robust design you can. The craft we are talking about are going to be next to impossible to fly because of the extreme speed, aerodynamic forces and heating involved, so that even a very experienced pilot will likely have no choice but to let McJeb do it for them.  That's not at all what you're trying to do, so it's not so helpful for you. AFAICT, you haven't actually posted a picture of your craft/attempt for a while. If you still haven't made it, perhaps doing so would elicit some helpful responses.

[Reinhart Mk.1]

i have video from my "successful" yet also non-successful Eve landing, damn i hope yall will be proud of me once i actually accomplish this. but hopefully my smooth commentary and charisma will make it enjoyable to watch

 

 

[Reinhart Mk.1]

45 minutes ago, herbal space program said:

posted a picture of your craft/attempt for a while

if the video didn't help i'll fire the game up again and post a picture!

[herbal space program]

2 minutes ago, Reinhart Mk.1 said:

if the video didn't help i'll fire the game up again and post a picture!

No, I think it's pretty clear what the issue is for you. It looks like you're trying to manually land the kind of ship that might be competitive in the dV contest we were talking about. I'm pretty sure none of us actually did that. We just used Hyperedit. If you actually want to land that thing, you need to adopt a wider stance. Set hardpoints and dummy tanks out, buttressed by struts, to mount sturdy lander legs as far away as possible from your CoG, You can then use the hardpoints to stage all that off when you're ascending. Or you could just make a wider lander. The tall-and-narrow thing is really about minimizing dV to orbit. 4X asparagus is easy to make so that it's a stable landing platform and is still plenty good enough to get you on and off.

[Reinhart Mk.1]

1 minute ago, herbal space program said:

Set hardpoints and dummy tanks out, buttressed by struts, to mount sturdy lander legs as far away as possible from your CoG

I HAD A DESIGN JUST LIKE THIS BEFORE  i just rushed this stage cause i was so worried about entering the atmosphere and overlooked it, same with a lot of other things

 

3 minutes ago, herbal space program said:

It looks like you're trying to manually land the kind of ship that might be competitive in the dV contest we were talking about. I'm pretty sure none of us actually did that.

i didn't even notice that... is that a good thing?

[Xavven]

Oh yeah, that ship is too tall and skinny. You need to widen your base and lower your center of gravity so you aren't limited to 100% perfectly flat and level landing sites.

One thing to try is to load just the Eve portion of your ship onto the runway or launchpad, and then take off into a hover just above the ground, and hover slowly over to a grassy area and practice landing. It'll give you an idea of how stable your craft is. Also try landing on various inclines to see what your ship will tolerate.

 

[GRS]

Don't understand what you mean by "manually land" the ship, hope it's cool, i'll be home around one and a half hour from now to watch your video, and i'm not really into that dV contest, yet my big lander took like 7.4k dV from below 1km ASL , and slim ships usually tumbled (flipped) quickly because of a quickly altered Aerodynamics, my big lander flipped during entry mainly because of lower surface area is wider than the upper ones, Aerodynamics will always get the lowest surface area in the front.

Edited February 22, 2019 by GRS

[Foxster]

20 hours ago, Laie said:

Well, lifting a single pod doesn't exactly justify a wide stack, does it?

I've just managed to make orbit for 5.5km/s(vac) from your starting position (200m high, boo!) -- using a 2.5m stack and quad vectors mounted to a Making History thrust plate. Payload was a Mk2pod and 15 tons of ore.

I didn't bother with building a rocket that has exactly the required amount of dV, I just took off with 6km/s and subtracted what was left. No special drag-avoidance shenanigans, and even a few struts and actual fuel lines just to spite you.

Video upload will have to wait until tomorrow, though -- if you're even interested, considering this isn't a stock vessel or your proposed payload. Besides, it's not yet quite as good as it needs to be.

BTW, may I propose lat 0.785, lon 107.93? It's a little closer to sea level.

Thinking about this...

What you posted is a skinny ship with no extra unneeded stuff bolted on, which is exactly what my craft are. It seems to confirm my original point. The only difference being that you've made it bigger to cope with a bigger payload. What were we disagreeing about again?

I've just put together a little craft that makes orbit from your launchsite using about 5.4dV, which is close enough to prove nothing. 

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. 

[herbal space program]

The disagreement was about your assertion that ONLY the 1.25m tanks are suitable for making efficient Eve lifters, because "the large engines and tanks are too draggy", which is exactly what you said upthread. Whether or not a pointy rocket is better than a stubby one was never at issue. Of course a pointy one is better, but so is a BIGGER one. But anyway, I agree that if you have not accepted that fact by now, you are not going to, so there's no point in belaboring it further, at least not on this thread.

Edited February 22, 2019 by herbal space program

[Laie]

19 minutes ago, Foxster said:

What you posted is a skinny ship with no extra unneeded stuff bolted on, which is exactly what my craft are. It seems to confirm my original point. [...] What were we disagreeing about again?

The main question I'm after is whether there is any inherent benefit to using wider stacks. To a smaller degree, it's about whether strict drag reduction measures are as all-important as you make them out to be. Of course the LVs are still as tall and skinny as I can make them (this is Eve, after all), but personally I believe that a craft can have actual struts and fuel lines, and even a limited amount of other dangly bits.

That rocket doesn't use any special drag reduction measures like linear construction stuff, and has a first stage that's more draggy than it needs to be. For all that, it shows promise of drawing even with yours... but the core is basically a 1.25m rocket scaled up 4x, so yes, similar enough.

Rather than tweaking this model, I'm scaling it up right now. Lets see where this goes, but my playtime for today is reaching it's end and I have nothing new to present at the moment.

[herbal space program]

1 hour ago, Laie said:

Rather than tweaking this model, I'm scaling it up right now. Lets see where this goes, but my playtime for today is reaching it's end and I have nothing new to present at the moment.

FWIW,  I was working on the 5m scale-up of roughly the equivalent stack last night, with 19 Vectors on the bottom of the core, and I was able to get to a very promising ascent profile in terms of acceleration, until I exploded. And exploded again. And exploded again. Which is to say,  I think at least for me the biggest challenge about showing that bigger is better is going to be heat management. I'm actually kind of curious what you are using for that on your own most recent ship, because a pointy fairing with a 2.5m heat shield right behind it still does not seem to be sufficient to keep my upper stage from vaporizing. It may just be that I'm still flying it by hand, and the oscillations of the Vector even when it's locked to prograde cause too much exposure of the sides. If that turns out to be the case, then I guess I'll have to abandon that approach and just see what McJeb can do with it.