EVE reentery, the brick wall

[Tidus Klein]

Hello guys, so ive been playing for a long time, and have done missions to just about every planet, i figured it was time for me to fo a eve return mission and ive come across a little bit of a hurddle....reentry stability.

no ive fought with this for a while trying to figure out why half way threw my decent i just flip and expose all my soft bits to the heat of eve, and learned that when you hit about 55.000M or so above eve you leterally hit a brick wall of atmo, making my 10M heat sheild produce get this 3000 points of drag as im going roughly 2800 m/s.....im slowing down so fast the Gmeter spikes to 6g's just of deceleration, ive tryed lowering my com closer to the heat shield, putting large wings on the back of my ship even a hefty RCS but nothing is able to over power that much drag. 

 

Can any body help? Also whats the normal DV needed to reach orbit from eve's sea level  

Edited October 26, 2016 by Tidus Klein

[Plusck]

I haven't tried the 10m heatshield yet. I had much the same problems with a 3.75m one. I ended up covering the whole thing with a large fairing, ultra-strutting it together, and still ending up at a 45° angle spinning wildly in the hopes of keeping heat spikes within survivable limits.

Still, if one 10m heatshield at the bottom creates too much drag at the bottom, then 3 10m heatshields should produce a lot more drag at the top, no?

[Aegolius13]

It sounds like you already have the key elements - low center of mass, drag on top, strong attitude correction.  You may just need more of these.  You could try some airbrakes on top, they will generate more drag than fins.

Some people put another inflatable heat shield on the back, just to generate more drag on the back.

Are you trying to land straight from Kerbin?  Might also try setting your periapsis higher and making a few passes to slow down.

[Magzimum]

I had the same problem, and asked the same question (for a 1.1.2 game):

I took the lessons learned, and built Jeb an Eve lander. I just put a bunch of wings and airbrakes on the top to prevent it from flipping, and nicknamed it "The Moose". For me the airbrakes were the magic part - and since I read only wings in your post, that may be worth a try. 

Thread comes with plenty of pictures to show the contraption at the top (24 (!!) airbrakes, 4 wings):

 

 

[Tidus Klein]

I would use airbrakes but they heat to quickly, i have already tried them and they just burn up before there any use, also im setting the orbit with the set orbit cheat, i just want to test my lander to see if it can make it to orbit with 3 kerbals.

once i get this figured out, ill have to figure out a way to make my lander moduler so i can build it in orbit around eve instead of sending one huge rocket

ill post a pic in a little bit

 

Edited October 26, 2016 by Tidus Klein

[Tidus Klein]

Haha! Success! My first eve lander is capable of bringing 3kerbals back from eve with all there sciance, with D-V to spare to, had a all other stage i could have burned and most of my orbiting stage still had fuel, going to optimize it and find a way to construct it in sute 

[Aegolius13]

Nice work!  Did you get the airbrakes to stop heating?  If they're occluded by the heat shield, they should be protected from heat but still produce drag.  But if the shield tips they could get unprotected.

[Tidus Klein]

This is her, just put another 10m heat sheild up top to fix the drag problem, 

have to add ladders and find a way to split it up and send it to eve orbit in parts, then assemble it there

might send it empty then run a supply tanker to it

Edited October 26, 2016 by Tidus Klein

[Ultimate Steve]

Well, as others have said stick another 10m heat shield on the other side of it for MOAR DRAG!

Worked pretty well for me.

[Magzimum]

Congrats!

If the airbrakes heat up too much, make sure to place them within the diameter of the 10m heatshield. Everything that sticks out will burn up. They will however still stabilize your craft, even if they are not directly exposed to the 3000 m/s fireball! 

[Tidus Klein]

It seems 10,000 d-v it the needed amount for a stock eve ascent, when i can get far installed i wonder how much that would save me in drag compensation  

also side question, how do i keep my legs from blowing up as soon as i touch down?

ps oceans on eve are pure death, but they make really cool effects if you wait till your 50m above then do your launch test

Edited October 27, 2016 by Tidus Klein

[magnemoe]

3 hours ago, Tidus Klein said:

It seems 10,000 d-v it the needed amount for a stock eve ascent, when i can get far installed i wonder how much that would save me in drag compensation  

also side question, how do i keep my legs from blowing up as soon as i touch down?

ps oceans on eve are pure death, but they make really cool effects if you wait till your 50m above then do your launch test

Think its 8 km/s from sea level, might be a bit less, my current design is unstable at lower speed a shame or I would manage with 2+2+1 aerospikes and upper stage.
will end up with 7 aerospikes, reaction wheels would increase stability but increases weight.
Nice idea to launch kerbal inside fairing. how high do you have to go before its safe to remove it?  

19 hours ago, Tidus Klein said:

This is her, just put another 10m heat sheild up top to fix the drag problem, 

have to add ladders and find a way to split it up and send it to eve orbit in parts, then assemble it there

might send it empty then run a supply tanker to it

For removing it, drop the top one first, you might want an decopler between as the shield will flop around a lot, 
Then flip ship around and get rid of the second shield. 
Best is to launch empty and top up in orbit. 
I assume you use the new fairing sections to keep upper heat shield in place? 

You could fly it to Eve on internal engines and refuel from Gilly

 

[Tidus Klein]

1 hour ago, magnemoe said:

Think its 8 km/s from sea level, might be a bit less, my current design is unstable at lower speed a shame or I would manage with 2+2+1 aerospikes and upper stage.
will end up with 7 aerospikes, reaction wheels would increase stability but increases weight.
Nice idea to launch kerbal inside fairing. how high do you have to go before its safe to remove it?  

Well the mk2 uses a more streamlined design, first stage is 9 vectors, that gets me about 6000m-7000, with the tanks on that, then i stage and drop the outer tanks, running on the remaining vector and 4 spikes, droping the vector after the spikes hit there stride which is around12,000m. I run on the 4 spikes till about 52-60,000m, stage the fairing and burn the rest if the stages till orbit.

so i would say, anywhere above 55000m is the safe zone to ditch the fairing

Edited October 27, 2016 by Tidus Klein

[crackerbal]

On 26/10/2016 at 7:46 PM, Tidus Klein said:

Haha! Success! My first eve lander is capable of bringing 3kerbals back from eve with all there sciance, with D-V to spare to, had a all other stage i could have burned and most of my orbiting stage still had fuel, going to optimize it and find a way to construct it in sute 

so what did solve this flipping issue ?

i actually have the same kind of truble and watching for some solutions, was already thinking about adding a fairing to cover the " center " but i'm not convince...

your solution was this rcs system on top of the first stage ?

edit : i finaly added a second 10m heatshield and 4 delta-deluxe winglet (only 4x370kg, witch dont drasticly reduces my twr or my deltaV ), using 20 mk2 radial parachutes and 4 aerobreakes, i'm able to land my 120t lander at 7.6 m/s, it results on breaking the landing legs coz of the payload, but the engines keep it landed and stable for a launch back .... i'm starting the most difficult now find the right deltaV and twr to put it in orbit again

Edited October 28, 2016 by crackerbal

[Sharpy]

I did a thing that worked. Nasty - but it did work.

The frontal large heatshield covers your ship.

Then there are three or four smallest heatshields, towards the end of the ship, extending outwards, angled - acting as fins.

[Aegolius13]

On 10/27/2016 at 4:34 AM, Tidus Klein said:

also side question, how do i keep my legs from blowing up as soon as i touch down?

A few options.   You can bring more chutes, though you hit diminishing returns.  Or you can do a retro burn, though this is hard to time efficiently.  Or you can bring done extra legs, and plan to lose 1 or 2.  On my recent Eve expedition, I used a combo of 1 and 3.

You can also use a stronger part as a leg, but I don't do this personally.

 

[Tidus Klein]

9 minutes ago, Aegolius13 said:

A few options.   You can bring more chutes, though you hit diminishing returns.  Or you can do a retro burn, though this is hard to time efficiently.  Or you can bring done extra legs, and plan to lose 1 or 2.  On my recent Eve expedition, I used a combo of 1 and 3.

You can also use a stronger part as a leg, but I don't do this personally.

 

I actually figured it out, if you set your damping and spring rate to half the stock value they absorb more of the impact, and actually survive, suprisingly they still hold the ship up right too. I thought they would just crush and not do anything at that spring rate

Edited October 28, 2016 by Tidus Klein

[Aegolius13]

4 hours ago, Tidus Klein said:

I actually figured it out, if you set your damping and spring rate to half the stock value they absorb more of the impact, and actually survive, suprisingly they still hold the ship up right too. I thought they would just crush and not do anything at that spring rate

Cool, I'll have to try that next time.  I've never really played around with those settings.

[Tidus Klein]

38 minutes ago, Aegolius13 said:

Cool, I'll have to try that next time.  I've never really played around with those settings.

 i personaly love messing with suspention and rovers

 

in fact i mainly use the model2 over the rugederized ones simply because they have more suspention travel, got a small rover that takes jumps like a champ,(jumps the whole launch pads track section one side to the other and just keeps going.) and i can turn it as hard as i want and it not flip in kerbin gravity

Edited October 28, 2016 by Tidus Klein

[crackerbal]

14 hours ago, Tidus Klein said:

I actually figured it out, if you set your damping and spring rate to half the stock value they absorb more of the impact, and actually survive, suprisingly they still hold the ship up right too. I thought they would just crush and not do anything at that spring rate

lol we are almost on the same progress in our conception i was actually asking me "what's about the breaking legs, how to fix it ? this guy on the forum put a lander with his legs intact, what am i doing wrong !? "

after experienceing some twr / acceleration issues with the "vectors" i switch them into 4 "dart" system ( less thrust but put me highter with the same amount of fuel ) by doing this i assume breaking legs will also break the "darts" on touch dawn, so i put a 2.5m découplers with the service bays under them to absorb the impact and accesory been used as a "lounch stability enhancers " ( plus oppening the service bays while landing is acting as aerobreakes )

i will try your solution of the spring rate even if i'm realy enthusiastic of my service bays system

can u tell me your total deltaV landed on eve ? that would helps me a lot

Edited October 29, 2016 by crackerbal

[Tidus Klein]

@crackerbal can do, but you will have to wait a bit till i get back from work today and have my birthday party :3

[crackerbal]

happy birthday ! @Tidus Klein <3

[Tidus Klein]

@crackerbal seems my most sucsessful versions ml1 and mk2 run about 2,000 d-v  for the lower atmo stage

ps thats 2,000 plus atmo dv, vac dv is double that

and intotal vac dv of 10,000

Edited October 29, 2016 by Tidus Klein

[crackerbal]

@Tidus Klein my actual deisgn have a total of 7728dv on Eve non atmo, i tested it yesterday once reach the eve orbit 112ap-98pe i still has 1056dv left, lacking only 300dv for a trip back to kerbin

i ment "hey lets put a bit more fuel so we will be fine", but when i ad any (even smaller oscarB) fuel tank on it, i'm losing the amount of deltaV lol.... idk if it's the KER experimental wrong readings of fuel flow or not, but as initialy my plan wasn't to bring this lander home but simply dock it to the ssto with some tourists i will probably reduce the amount of fuel better then incrase... anyways going to try this out on the both ways

Ps : my actual biggest problem is the acceleration during ascent after 1st stage around 11-13km i'm usually losing a lot of velocity dont know how to fix it

[Tidus Klein]

Well i dont like to accelerat alot in the lower atmo, and you probably need ether better twr or better aerodynamics, even at that high eves molasoshpere is still just as thick or thicker then kerbins

but maybe im doing something wrong, because i need atleast 10,000 dv to get to orbit, maybe i should just floor it and ignore atmo losses

Edited October 30, 2016 by Tidus Klein