Gravity turn on Eve

[Firemetal]

(To tell the truth, I don't know if doing a gravity turn manually on Eve is possible. Maybe it is with winglets, maybe not. Feel free to correct me.)

So most of us know that to get to orbit efficiently, you need to do a gravity turn and have an AoA of roughly 45 degrees at 10km on Kerbin. This is done by tipping over gradually while you are ascending. Getting to orbit this way is the most efficient and will get you into orbit using the least amount of DV. However on Eve, such a maneuver is very difficult and most people just go straight up and turn after they have gotten up high enough not to flip over when they turn it the slightest. Doing a gravity turn on Eve like Kerbin is hard and makes getting to orbit not as efficient as on Kerbin. In fact some might say it is impossible to do. Until... now.

Before 1.2, using the SAS to point in a certain direction, such as prograde, retrograde, radial and so on could cause an engine to gimbal uncontrollably and force you to keep the ship focused on a certain direction manually. This bug was fixed in 1.2 and now, if you get it right, you can have that... do the gravity turn for you. All you have to do is move slightly to one side while you are firing the engines and the prograde vector will move forward in that direction. Then just hold prograde and you will follow it and keep it moving.

Now yesterday, I built an Eve lander, dropped it through Eve's atmosphere and landed it. This was a test run to land and fly to orbit so I used the debug menu to edit it into low Eve orbit. It took me a few tries to get the optimal launch, (i.e make it go straight up and not flip over. ) but I did it and on this one attempt, I was tilted slightly down the navball on the 90 line. My prograde vector was slowly moving down at the same time so I clicked on hold prograde. I then watched it slowly tip over until at 10 km, it was at 45 degrees AoA. Now I know since Eve's atmosphere ends at 90 km and Kerbin's ends at 70 km that this is a less optimal gravity turn maneuver since you are going to want to be going up more and not going sideways as much But I got into orbit with tons of DV to spare and also did what I call an optimal flight to orbit. Sure the nose got hot at one point and almost blew up and as I said previously, this wasn't an optimal gravity turn but it worked.

So... what I am wondering is, if you use this trajectory to orbit, how small can you make your landers? Also what are your thoughts on this discovery? And have any of you encountered this yet?

Thanks.

Fire

[Daripuff]

A gravity turn is still the most efficient way to get to orbit of Eve,  but 45°at 10km is WAY too shallow a turn. 

 

You do the gravity turn to balance out the losses of fighting gravity with the losses of air resistance.  

On a planet with no atmosphere, and therefore no air resistance to fight,   you go full horizontal the moment your altitude is higher than the hills you might hit,  no gravity turn there. Or rather,  a gravity turn so shallow it might as well not exist. 

On a planet with a truly brutal atmosphere like Eve?  You need to be more vertical for longer.  Air resistance down low is much much more difficult to fight than gravity,  so you need to tune your gravity turn much steeper. Something like 45° at 25 or 30km.  You want to go nearly straight up until you're in thinner air. 

If you're doing 45° at 10km on eve,  you're wasting far,  far too much fuel fighting that brutal atmosphere.  

Edited December 8, 2016 by Daripuff

[Firemetal]

1 minute ago, Daripuff said:

A gravity turn is still the most efficient way to get to orbit of Eve,  but 45°at 10km is WAY too shallow a turn. 

 

You do the gravity turn to balance out the losses of fighting gravity with the losses of air resistance.  

On a planet with no atmosphere, and therefore no air resistance to fight,   you go full horizontal the moment your altitude is higher than the hills you might hit,  no gravity turn there. 

On a planet with a truly brutal atmosphere like Eve?  You need to be more vertical for longer.  Air resistance down low is much much more difficult to fight than gravity,  so you need to tune your gravity turn much steeper. Something like 45° at 25 or 30km.  You want to go nearly straight up until you're in thinner air. 

If you're doing 45° at 10km on eve,  you're wasting far,  far too much fuel fighting that brutal atmosphere.  

Yup I agree. I stressed this in my thread.

19 minutes ago, Firemetal said:

Now I know since Eve's atmosphere ends at 90 km and Kerbin's ends at 70 km that this is a less optimal gravity turn maneuver since you are going to want to be going up more and not going sideways as much But I got into orbit with tons of DV to spare and also did what I call an optimal flight to orbit. Sure the nose got hot at one point and almost blew up and as I said previously, this wasn't an optimal gravity turn but it worked.

Fire

[LordKael]

clearly, a disposable propellor is the best way. Build yourself a stock bearing. Can slow you down for the landing portion of the descent. and get you through the thick part of the atmosphere with nothing but electrical. 

[Foxster]

Got a picture of your craft?

I confirm that Eve is tad more forgiving in terms of heatplosion that she used to be. Not easy still, but slightly nicer about how she kills you. 

You can turn a bit earlier than before and tilt it over a little more. So you can save some dV with a more graceful gravity turn. But...the drag is pretty much as before and if you do a Kerbin-like lift you'll still lose a lot to drag, especially if your craft is angled sharply into the wind. 

[Leafbaron]

1 hour ago, LordKael said:

clearly, a disposable propellor is the best way. Build yourself a stock bearing. Can slow you down for the landing portion of the descent. and get you through the thick part of the atmosphere with nothing but electrical. 

I had a much similar idea a while back using electric props from firespitter. 

[Firemetal]

1 hour ago, LordKael said:

clearly, a disposable propellor is the best way. Build yourself a stock bearing. Can slow you down for the landing portion of the descent. and get you through the thick part of the atmosphere with nothing but electrical. 

 

11 minutes ago, Leafbaron said:

I had a much similar idea a while back using electric props from firespitter. 

I have tried building these before and I have trouble understanding the kraken tech behind them. I might try it but sometimes it is better to go with a more simple design even though it is going to be a pain in the butt to get there.

 

52 minutes ago, Foxster said:

Got a picture of your craft?

I confirm that Eve is tad more forgiving in terms of heatplosion that she used to be. Not easy still, but slightly nicer about how she kills you. 

You can turn a bit earlier than before and tilt it over a little more. So you can save some dV with a more graceful gravity turn. But...the drag is pretty much as before and if you do a Kerbin-like lift you'll still lose a lot to drag, especially if your craft is angled sharply into the wind. 

Yes the whole point here is saving DV, no matter what the drag is like. I have disliked having to go straight up so much since so much fuel is going out the drain but this kind of fixes it for me. It isn't the best idea though and I understand that but with a bit of playing around someone who has a little more experience than me can probably get it to actually make getting to orbit a little less DV heavy than it is.

And I'll edit the OP with a picture of the craft in the VAB later.

Fire

[quasarrgames]

1 hour ago, LordKael said:

clearly, a disposable propellor is the best way. Build yourself a stock bearing. Can slow you down for the landing portion of the descent. and get you through the thick part of the atmosphere with nothing but electrical. 

 

2 minutes ago, Leafbaron said:

I had a much similar idea a while back using electric props from firespitter. 

It's a great idea, but a bit tedious to achieve. I tried a stock electrical propeller craft on eve before:

The problem is, eve's thick atmosphere and high gravity mean that propellers have a lot of drag and friction, and don't turn as well. This plane here flew at up to 60m/s on kerbin. On eve? 20m/s. And that's at sea level. By about 15km, it could barely keep itself in the air.

And this was with no payload, too. It would take a massive plane to get even the lightest eve semi-landers to orbit. And it would be a slow ascent, too.

So, is it possible? Yes. Is it feasible? with a good propeller, yes. Would it be challenging? yes.

[Leafbaron]

Just now, Firemetal said:

 

I have tried building these before and I have trouble understanding the kraken tech behind them. I might try it but sometimes it is better to go with a more simple design even though it is going to be a pain in the butt to get there...

The idea never came to fruition because anytime i tried testing a craft with one of the props from firespitter it crashed my game so i gave up on it. 

[Firemetal]

Just now, Leafbaron said:

The idea never came to fruition because anytime i tried testing a craft with one of the props from firespitter it crashed my game so i gave up on it. 

Sucks man.  People have done this with stock kraken drive props but I haven't had such a great time building them.

Fire

[Leafbaron]

2 minutes ago, quasarrgames said:

 

It's a great idea, but a bit tedious to achieve. I tried a stock electrical propeller craft on eve before:

The problem is, eve's thick atmosphere and high gravity mean that propellers have a lot of drag and friction, and don't turn as well. This plane here flew at up to 60m/s on kerbin. On eve? 20m/s. And that's at sea level. By about 15km, it could barely keep itself in the air.

And this was with no payload, too. It would take a massive plane to get even the lightest eve semi-landers to orbit. And it would be a slow ascent, too.

So, is it possible? Yes. Is it feasible? with a good propeller, yes. Would it be challenging? yes.

that is awesome! if it can get to 15km, thats 15km you don't have to get to with rocket fuel. My idea was for a detachable prop that would get the lander as high as possible in the atmosphere before switching to a closed cycle engine and ditching the prop. The lander would then rendezvous with the mother ship.... I will have to see if firespitter is working with 1.2.2.... I really want to go to eve but I don't wanna leave anyone behind and engineering a 200 ton lander is not something I really wish to do. I gotta give mad respect to the guys who do though. 

Edited December 8, 2016 by Leafbaron

[wumpus]

20 hours ago, Leafbaron said:

that is awesome! if it can get to 15km, thats 15km you don't have to get to with rocket fuel. My idea was for a detachable prop that would get the lander as high as possible in the atmosphere before switching to a closed cycle engine and ditching the prop. The lander would then rendezvous with the mother ship.... I will have to see if firespitter is working with 1.2.2.... I really want to go to eve but I don't wanna leave anyone behind and engineering a 200 ton lander is not something I really wish to do. I gotta give mad respect to the guys who do though. 

There's a Scott Manley video that includes a vessel that lands on land, that heads to a mountain (or sufficiently high elevation and thinner atmosphere) plus an airship that leaves that, heads to water and back (which leads me to believe the initial site was somewhat near Ocean and relatively low.

I have no patience for ground travel in KSP (I learned my lesson on the Mun.  Minmus you can often get away with RCS flight, but munar buggies can't be expected to make it to a new biome in the time it takes to orbit dock and land a lander multiple times).

I have to wonder if you could airlift an Eve ascender part by part?  I guess not, since it would probably have to attach "sideways" on the ground and that would defeat the point of a >=1.1 Eve ascender (drag would be too high).

[Leafbaron]

1 minute ago, wumpus said:

There's a Scott Manley video that includes a vessel that lands on land, that heads to a mountain (or sufficiently high elevation and thinner atmosphere) plus an airship that leaves that, heads to water and back (which leads me to believe the initial site was somewhat near Ocean and relatively low.

I have no patience for ground travel in KSP (I learned my lesson on the Mun.  Minmus you can often get away with RCS flight, but munar buggies can't be expected to make it to a new biome in the time it takes to orbit dock and land a lander multiple times).

I have to wonder if you could airlift an Eve ascender part by part?  I guess not, since it would probably have to attach "sideways" on the ground and that would defeat the point of a >=1.1 Eve ascender (drag would be too high).

I feel ya about the ground travel. before 1.2 I had any idea to rover around the Mun and collect the science from every biome and then send the science and rover driver back to Kerbin. It was slow going and painful. It did yield quite a bit of science. But if quickly progressing is what you want, Rovers are not the way to do it. 

[LordKael]

20 hours ago, quasarrgames said:

It's a great idea, but a bit tedious to achieve. I tried a stock electrical propeller craft on eve before:

The problem is, eve's thick atmosphere and high gravity mean that propellers have a lot of drag and friction, and don't turn as well. This plane here flew at up to 60m/s on kerbin. On eve? 20m/s. And that's at sea level. By about 15km, it could barely keep itself in the air.

And this was with no payload, too. It would take a massive plane to get even the lightest eve semi-landers to orbit. And it would be a slow ascent, too.

So, is it possible? Yes. Is it feasible? with a good propeller, yes. Would it be challenging? yes.

I would think that the thicker atmosphere would sort itself out. You'd get more drag from the prop, but more lift from the wing surfaces, so it would just be a slower flight. A patient player could, in theory, climb until Eve's atmosphere was around the same density as 10km on Kerbin. This should be a huge boon to dV requirements. Yes, you'd need a massive plane, but if you sent a lander made of mostly mk2 parts, with a balanced mass, and then built modular wings and propellor, you could attach via docking ports in orbit before the descent, and dispose of them on the way back up

[foamyesque]

11 hours ago, wumpus said:

I have to wonder if you could airlift an Eve ascender part by part?  I guess not, since it would probably have to attach "sideways" on the ground and that would defeat the point of a >=1.1 Eve ascender (drag would be too high).

Build a spaceplane lander with integral ISRU. Fly around Eve as much as you like, as long as you land in places with ore, and then head to a mountaintop for final ascent.

[wumpus]

17 hours ago, foamyesque said:

Build a spaceplane lander with integral ISRU. Fly around Eve as much as you like, as long as you land in places with ore, and then head to a mountaintop for final ascent.

I was thinking more docking by taxing over something and retracting landing gear.