If I ever make it back from Eve

[FleshJeb]

@Laie Do you have the time and inclination to rerun those ISP curves on page 3 out to 50km, and including nukes? I’d like to see where the Aerospike and the Nerva cross over. I have an idea involving wings...

[Reinhart Mk.1]

this entire journey REALLY has been me correcting literally every tiny mistake, there are A LOT of mistakes.

[Laie]

11 hours ago, FleshJeb said:

@Laie Do you have the time and inclination to rerun those ISP curves on page 3 out to 50km, and including nukes? I’d like to see where the Aerospike and the Nerva cross over. I have an idea involving wings...

ISP is simple to do, no problem. Doing the other graphs would be more complicated and, I'm afraid, not worthwhile. I'll try anyway, but can't upload pictures at the moment, please be patient.

in words: Nerva is among the worst engines at 16km,  and by 17km it's off the chart (I'm cutting off at 350s and 30km). The crossover point where it becomes the best is 16.5km.

In other news, I've set a new record.

Full disclosure: I've used the offset tool to sink the upper stage engine into the lifesaver.

 

Edited March 4, 2019 by Laie

[Foxster]

5 hours ago, Laie said:

In other news, I've set a new record.

Only for the challenge and no one has posted in there for a while. As you say, things have changed since then. I think around 18t or so is possible now. 

[FleshJeb]

7 hours ago, Laie said:

in words: Nerva is among the worst engines at 16km,  and by 17km it's off the chart (I'm cutting off at 350s and 30km). The crossover point where it becomes the best is 16.5km.

Good enough, thanks for the info. I should be able to float something up there easily enough on aerospikes. Right now I'm looking at 4 or 5 aerospikes and 2 or 3 nukes to push a 2.5m stack.

[herbal space program]

1 hour ago, FleshJeb said:

Good enough, thanks for the info. I should be able to float something up there easily enough on aerospikes. Right now I'm looking at 4 or 5 aerospikes and 2 or 3 nukes to push a 2.5m stack.

I'll be interested to see if you can get any value out of the nukes. I found that their <1.2 TWR  in Eve gravity, even in vacuum, made them next to useless for an efficient lifter.  The Wolfhound OTOH I found to be pretty useful.

[FleshJeb]

12 minutes ago, herbal space program said:

I'll be interested to see if you can get any value out of the nukes. I found that their <1.2 TWR  in Eve gravity, even in vacuum, made them next to useless for an efficient lifter.  The Wolfhound OTOH I found to be pretty useful.

On Kerbin, with wings, I can escape with a starting TWR of 0.20 on nukes. I'm almost certain I'm going to have to use KRPC to independently run the aerospikes at reduced throttle. I just need to do that long enough for the total thrust to beat the total drag by about 2:1. What that means is this thing needs to be as slippery as possible.

I won't be using any MH parts--I just don't think they belong in challenges. Personal preference.

[Reinhart Mk.1]

F to pay respects

https://imgur.com/a/J17vL7b

one little girder cause this entire thing to tip over, yall have faith in me this thing is gonna make it once i land it properly. okay talk amongst yourself i love u all have a good day <3

[herbal space program]

10 minutes ago, FleshJeb said:

On Kerbin, with wings, I can escape with a starting TWR of 0.20 on nukes.

On Kerbin, absolutely. I generally try to get it up to like 0.3 for my space planes, so that I can switch over sooner, but it's clearly the best way to get to LKO with the most possible dV and a useful TWR. On Eve however, I found that both the high gravity and the high altitude required to get the nukes to a TWR of even 1.2 made it so that I could not circularize on them without first lobbing my ship so high on regular engines that the better ISP was totally offset by the resulting gravity losses. But that's just me! Maybe I didn't try hard enough...

[Reinhart Mk.1]

also HOW do i embed imagur photos? it never works for me

[herbal space program]

2 minutes ago, Reinhart Mk.1 said:

also HOW do i embed imagur photos? it never works for me

Right-click on the image in your Imgur album, select "copy image address", then click somewhere in your editor window and and hit ctrl-v to paste:

 

Edited March 4, 2019 by herbal space program

[Reinhart Mk.1]

Thank you! If this design doesn't make it to orbit I've failed as a pilot

[Reinhart Mk.1]

idc if im being annoying i REALLY want to leave this planet but oh god taking off from way above sea level vs. asl is SO HELPFUL, only took me 2 hours to figure out how to land in a specific area

[GRS]

@Reinhart Mk.1, nice design, wish you can succeed with that design, i know you can, since the first times...

[FleshJeb]

Last night, I tried various combinations of Aerospikes, Nervas, and Vectors. This plane is about 150T full, and 50T empty, with approx 80 lift units of wing @ 5deg incidence. It re-enters and lands beautifully, but there's way too much wing, and it's inducing far too much drag to accelerate. Also, oddly enough, the 2.5m service bay is draggier than every other part. Solar panels and radiators won't deploy through a fairing, so I might be stuck with it. In the end, I'll probably abandon the ISRU in the front, since I can de-orbit with 25m/s, and land fully-fueled.

There's no way I'm getting anything to orbit from sea level, so I'm going to try some mountaintops with a more stripped-down design.

[Atkara]

21 minutes ago, FleshJeb said:

There's no way I'm getting anything to orbit from sea level, so I'm going to try some mountaintops with a more stripped-down design.

What exactly are you after?

[FleshJeb]

Just now, Atkara said:

What exactly are you after?

SSTO from somewhere on Eve. I know it's been done with what I'll loosely describe as a "Brad Whitstance-style" fast-climbing, minimal wing plane, but I'm trying for an slow-climb, high L/D ratio "AeroGav-style" plane.

I haven't been on Eve since pre-1.0 days, when I just barely made it back to orbit from a mountaintop with some asparagus-staged monster. It's a lot easier now.

[Atkara]

40 minutes ago, FleshJeb said:

SSTO from somewhere on Eve.

I thought so -had to make sure though. I try my hand at it every now and then  

[herbal space program]

1 hour ago, FleshJeb said:

SSTO from somewhere on Eve. I know it's been done with what I'll loosely describe as a "Brad Whitstance-style" fast-climbing, minimal wing plane, but I'm trying for an slow-climb, high L/D ratio "AeroGav-style" plane.

I haven't been on Eve since pre-1.0 days, when I just barely made it back to orbit from a mountaintop with some asparagus-staged monster. It's a lot easier now.

I've been spending my time lately trying to see how close I can get to making an SSTO with an extra-big lifter launching from 4000m:

 

I've succeeded in getting the entire 80 ton+ core stage of something very similar to the upper version on orbit several times, once with 750 m/s to spare, but I apparently never took a screenshot. The lower panel is an earlier version that Aaalmost made orbit as shown, staging off only some engines from the side stacks, but ultimately plunged back into the atmo due to insufficient TWR. My latest version is looking pretty promising, but it's bugged out somehow, shaking itself apart after I stage off the side stacks even if there is no contact with the core stage. Anyway, I've got a ways to go on this concept but I feel like I'm making progress. I also wanted to share my high-altitude takeoff spot coordinates (displayed on the HyperEdit dialog upper left) , as this is one of the best spots I've ever found. It's a large, more or less flat area just above 4000m on the shoulder of the tallest peak, which I suspect would make a pretty good runway. I suppose you could also poke around in that area and see if you can find a good sky ramp going up the peak. @Laie was asking about this a while back, so I'm pinging him as well.

Edited March 5, 2019 by herbal space program

[farmerben]

 

Valentina is out to prove it is possible to land a rocket on Eve without inflatable heatshields.  She designs a craft with 1 vector, 4 mammoths, and 4 external fuel tanks.  She has one large reaction wheel but it will be toggled off part of the time.  The external fuel tanks are designed to put the center of lift at the center of mass when full.  The elevons do not respond to pitch,roll, or yaw, but when delpoyed they move the center of lift toward the nose.  Valentina uses her main engines to prevent any buildup of downward velocity.

Between 60km and 30 km there is always the risk of gaining too much vertical velocity.  Valentina uses the gimbal of the mammoths to pitch from retrograde to vertically up.

 

She lets go her external tanks, and uses up most of the fuel in the mammoths to keep her speed down.  When almost empty she reaches a terminal velocity around 600m/s.  Enough fuel remains to kill speed before parachute deployment, and again for touchdown.

 

 

I cheated and used infinite propellant for the mammoth stages.  In theory the full craft would have Eve sea level TWR 1.79, vacuum TWR 6.2 and dV of 2352m/s at Eve sea level or 3833 m/s vacuum.  As it was nearly empty it was unstable and flipped over.  That happens less when full, or 4 strakes could fix it.

 

At an altitude of over 80 km and with surface velocity minimal, I ditched the mammoths and turned off infinite propellant.  The core vector has vacuum TWR of over 2 and 4000 dV.  I'm not sure what minimum altitude this would be rated for.  At sea level its thrust is too low.

 

This little top bike has 3 ants and 3 fuel cells, and a xenon.  Giving it a vacuum TWR of .9.  

 

The liquid fuel runs out and we only have one battery, but 4 solar panels is just enough to stay fully charged in direct sunlight near Eve.

[herbal space program]

2 hours ago, FleshJeb said:

It re-enters and lands beautifully, but there's way too much wing, and it's inducing far too much drag to accelerate....

It seems like one thing that would really help to make this work would be some kind of deployable wing.  I know inflatable heat shields generate quite a bit of lift, but I expect they're probably too problematic in every other way...

[farmerben]

 

This time I turned on infinite fuel for the way down and no cheats for the way up.  Its much harder to land a fully fueled rocket, but if you fool with it long enough you can get to mount lookatthat.  

 

Going up with full fuel.  I pegged vertically up put the hammer down.  It still flipped but I was going over 1200m/s straight up at that point, and I already had a space apoapsis at that point.  It was a nice steady flip so I could go full throttle 50% of the time too.  

The vector stage was close to 200km altitude and minimal velocity.  But it circularized fine at 1.5Mm.

[farmerben]

5 hours ago, FleshJeb said:

Last night, I tried various combinations of Aerospikes, Nervas, and Vectors. This plane is about 150T full, and 50T empty, with approx 80 lift units of wing @ 5deg incidence. It re-enters and lands beautifully, but there's way too much wing, and it's inducing far too much drag to accelerate. Also, oddly enough, the 2.5m service bay is draggier than every other part. Solar panels and radiators won't deploy through a fairing, so I might be stuck with it. In the end, I'll probably abandon the ISRU in the front, since I can de-orbit with 25m/s, and land fully-fueled.

There's no way I'm getting anything to orbit from sea level, so I'm going to try some mountaintops with a more stripped-down design.

I'm not convinced the aerospikes are worth it, and the nervas definitely not.  I'd try a combination twin boar and vector. 

[FleshJeb]

7 minutes ago, farmerben said:

I'm not convinced the aerospikes are worth it, and the nervas definitely not.  I'd try a combination twin boar and vector. 

The Spikes have superior ISP to the vector/twin boar for the vast majority of the atmo profile. Right now it's a drag problem, not a thrust problem. I've got so much lift, I actually have to throttle back the three Spikes to fly surface prograde without pitching up too much.

I can pack 7 engines into a rear end 2.5m fairing. They're nearly dragless, and I could make them completely so. If I get rid of half the wings, I should be able to get some good flying done. 4 Nervs would be good enough to push it NOW, if I could get it to 16.5km on the Spikes.

I still have lots of fiddling to do, but I'm not convinced it's unreasonable yet.

[farmerben]

Sounds like you're darn close.  A mountain would probably do it if you only need oxidizer to get to 16.5 km.  

The KSP wiki may not be accurate for drag information.  It just says drag equals .02 for almost everything.   I hope that means they all have the same drag per unit area, but I'm not sure.

I'd consider any altitude under 30km to be a giant fuel suck.  In which case some good canards could control pitch while you blast for altitude.  It would also allow a lower AOA on the main wing which could make a huge difference in terms of drag.  Canard forces tend to be more favorable than tail elevators.