Duna landing 1.0.5

[Stigy]

Hello.

Is it possible to land on Duna without using engines ? In 1.0.4 used engines for deorbitation only, chutes done the rest of the job. Now (in 1.0.5) drag is too low to brake my lander, and the chutes are destroyed above 400 m/s, so i need to use engines for braking under 400 m/s. Is there a way to do Duna landing without using engines for braking ? Edited November 17, 2015 by Stigy

[AeroGav]

I managed to put an airplane on Duna, with plenty wing area and 3 vernier engines to provide vertical lift. I quicksaved about the time of this screenshot and had about 20 attempts to put it down. 5 fatal attempts, 14 nonfatal wrecks and one landing where everything stays in one piece. Sorry not much help really, as it sounds like less bother to do what you're attempting !




[URL=http://s1144.photobucket.com/user/narostel/media/LVN%20Mod%201%20test/2015-11-13_00029_zpshkgkyztg.jpg.html][IMG]http://i1144.photobucket.com/albums/o492/narostel/LVN%20Mod%201%20test/2015-11-13_00029_zpshkgkyztg.jpg[/IMG][/URL]
[URL=http://s1144.photobucket.com/user/narostel/media/LVN%20Mod%201%20test/2015-11-13_00038_zpsg7e3c3kx.jpg.html][IMG]http://i1144.photobucket.com/albums/o492/narostel/LVN%20Mod%201%20test/2015-11-13_00038_zpsg7e3c3kx.jpg[/IMG][/URL]
[URL=http://s1144.photobucket.com/user/narostel/media/LVN%20Mod%201%20test/2015-11-13_00040_zps59em9lgi.jpg.html][IMG]http://i1144.photobucket.com/albums/o492/narostel/LVN%20Mod%201%20test/2015-11-13_00040_zps59em9lgi.jpg[/IMG][/URL]

[Warzouz]

Yes I've notice that in 1.0.4 regular chutes could be open around 500 to 700m/s (I don't remember precisely). In 1.0.5 it's 220m/s, lower than on Kerbin.

It's seems to be a bug. Thiner atmo shouldn't destroy chutes.

[AeroGav]

Something i often do early in my career is use wings to slow down from re-entry to parachute speed. Judging from my "aircraft landing" shot, that may be possible here....

edit - if you bring enough aero surfaces to have a stall speed below 220m/s, then you can probably leave off the heatshield to offset the weight of wings etc. Duna's thin atmo and low gravity mean winged entry without heatshield is survivable in 1.05, if you come in shallow and stay pitched up to 20-30deg angle of attack. Edited November 16, 2015 by AeroGav

[Warzouz]

No heatshield is needed when coming from low Duna orbit.

[moogoob]

1.05's affected Duna's aerodynamics? I'm going to have to run some tests.

[Racescort666]

I thought safe deploy of drogue chutes were like 500+ m/s? Anyway, mach number is important for chute deployment, I haven't messed around with it much in Kerbal to know whether mach number is the driver for chute survival but I know it is one of the factors IRL.

One more suggestion, air brakes for entering Duna. I didn't really find a heat shield necessary for Duna but if your probe is too heavy then air brakes might help increase drag sufficiently to slow you to safe chute deployment speeds.

[Claw]

I'm hightly interested in hearing about people's experience on Duna (and elsewhere).

There were some atmosphere changes in 1.0.5 to fix things like aerobraking. Sounds like the changes were a little further reaching.

Cheers,
-Claw

[RocketPropelledGiraffe]

I just landed on Duna (still there, getting back is tonights project), and actually got flaming effects for the first time I can remember. I was getting down from an 80 km orbit with about 8 km periapsis. However, a heat shield was not necessary.

I got scared when I was still going very fast at 10 km down, and used the engine to slow down and safely deploy the drogue chutes.
Drogue chutes then easily slow you down enough to safely deploy the normal chutes.

4 radial drogue chutes and 4 radial normal chutes managed to bring my 14 t lander down to 18 m/s at 4500 m. A little thrust was almost always necessary, so no real change there.

[Guest]

Landing without engines? Well, that's going to depend on the design of the lander. Post some screenshots or better yet post a link for the craft file. I use the engines on rockets a little bit just to bring the surface velocity down just before landing so that the landing gear doesn't break. For spaceplanes, I thought Duna was way easier than Kerbin as far as reentry was concerned, but landing was not as easy mainly because of the higher surface velocity and lack of a nice long flat landing spot. My plane kept rolling over and crashing, but that could probably be cured with design changes. I just took the easy way out by adding 2 parachutes and landing on the engine, using the engine to lower velocity before touching down, then rolling over onto the gear. I haven't tried using a rocket yet in 1.05, but if you post the craft file, I'll give it a go and see what's going on.

Edit : and as far as the atmospheric breaking. I reentered with a PE of around 20km coming from Kerbin. I tried to use an AoA of 30 degrees, but because of fuel balancing issues, was not able to maintain that. 10 degrees was all I was able to keep. But it didn't matter, I didn't have to retry because the plane survived. Duna capture was successful, and on the 2nd pass I readjusted PE to 20km and landed after about a 10 minute reentry. All in all a good mission and not too hard. I'm setting up to test Jool and Laythe now. Edited November 16, 2015 by Otis

[Stigy]

I'm nearly sure, its not the craft problem. Main problem is, that drogue chute can be deployed only if velocity drops to 399 m/s. You have to use engines to make it so. Edited November 17, 2015 by Stigy

[KerikBalm]

It turns out that Duna's atmospheric pressure is now a mere 1/3 of what it used to be.
0.0667 atms at 0 elevation... it used to be 0.2 atms....

I had a duna aircraft.... it can't take off anymore.

I just tried to land my laythe SSTO (described below)... I could slow it down to about 150 m/s on wings, slow enough to deploy its braking chutes... but so far I haven't been able to get any of its crew alive on the surface.

Duna feels very different now... I was actually wanting a more proper mars analogue with something like 0.01 atms...
Duna just became more like that... ~0.06 atms at the lowest point (since the lowest point is above 0 "elevation", its more than 0.0667 atms).

I think my Duna base in my save may be pretty heavily affected.
I won't complain though... Duna just got a whole lot more interesting, at least its more of a challenge now.

I noticed hey also reduced Laythe's surface pressure by 25%... from 0.8 atms to 0.6 atms.
As a result, testing something on Kerbin does not mean it works on laythe.
I spend a long time making a Kerbin SSTO sea plane that can land on and take off from water with a full fuel load.

Well the landing speed is now higher, and the takeoff... I couldn't get it off the surface... I'd hydroplane to 120m/s, but as soon as I'd pull up, the drag of the rear pontoons with hydroplane going down into the water would slow me down too much, and the wings didn't produce enough lift to lift the plane without the rear pontoons going deeper, I'd just keep skimming the surface... if I continued to build up speed... at about 130 m/s, my pontoons with the hydroplanes would break off...
It lifted off Kerbin's oceans easily... :/

I was eventually able to get it off by setting the deploy state on the hydroplanes and some of my control surfaces to generate more lift, ie effectively a higher angle of attack/incidence.
I think I'll set up an action group for that, and tweak some hydroplane and wing incidence positions a little more. Edited November 16, 2015 by KerikBalm

[Guest]

[quote name='Stigy']I'm nearly sure, its not the craft problem. Main problem is, that drogue chute can be deployed only if velocity drops to 399 m/s. You have to use engines to make it so.[/QUOTE]

Think of it like this, a brick and a feather are not going to fall at the same rate unless they are in a vacuum. So, Duna's atmosphere is thinner. Craft designs that worked in the past may or may not work now. Getting the craft to slow down enough to deploy the drag shoots will require either changing the reentry procedure or changing the craft to create more drag or both. The craft design definitely matters.

[Nansuchao]

[quote name='Claw']I'm hightly interested in hearing about people's experience on Duna (and elsewhere).

There were some atmosphere changes in 1.0.5 to fix things like aerobraking. Sounds like the changes were a little further reaching.

Cheers,
-Claw[/QUOTE]

I made some tests with FAR on Duna and Eve. Landing on Duna needs some rocket power, the gravity seems lighter and the atmo is really thin. You can't land just with parachutes, but the heating isn't an issue. BTW EVE is maybe worst than before. At high altitude, the heat is trong, but the atmosphere doesn't slow you much enough (or at all). Trying to aerobrake il impossible, and also to re-enter from low orbit needs rocket power to slow down and a lot of parachutes, cause the gravity and the pressure make you maintain more than 30 m/s of vertical speed with chute on a simple lander.
I like the new changes, they seems to bring a little more "realism".

[KerikBalm]

Aerobraking is perfectly possible at Eve if you brought a heatshield:
[img]http://i.imgur.com/nOcCmSv.png[/img]

That got down *mostly* ok
I had a few control surfaces that stuck out a bit too much.
Also the airbrakes for keeping it stable had to be pulsed, as they'd overheat, and I left the airbrakes on a little too long and lost one of them before it retracted into the "wind shadow" of the heat shields.... but I had 12 or 16 of them I think, so it was ok with only 11 or 15.
I also had 8 control surfaces on the lander, 4 on the outer asparagus stage, 4 on the middle.
The 4 outer ones were lost, but it was still stable and controlable enough on ascent with the remaining 4 control surfaces.

[Warzouz]

That's sad Duna was turn into a nearly vaccuum world. There aren't much atmospheric worlds and Duna was quite fun to explore, even it's biomes and surface features are very poor.

[Pecan]

[quote name='Warzouz']That's sad Duna ... even it's biomes and surface features are very poor.[/QUOTE]

Dres resort - we're ready to meet your needs. All you need to bring is your wallet.
([I]nailed it again[/I])

[Violent Jeb]

Great.. new changes that make it even harder to reach the existing planets.

Why not add new planets for the experienced players rather than changing /making.more.difficult / locking.out.the.game to 50% of people who simply don't have the time to relearn the game every 3 months. Duna is supposed to be the easy starter planet, remember?

Its ridiculous because I can BARELY accomplish a Duna landing as it was in 1.0.4, and now i get to relearn if i can even do that before i worry about the other, also now more difficult planets.

They make changes that nobody seems to ask for. People wanted jool to be easier to aerobrake, i remember that. What was wrong with duna? it needed biomes, not borked atmosphere.

[KerikBalm]

I actually like that its a near vacuum world... We were missing a proper "its got an atmosphere, but its barely there" world.
It seems they changed the mw of the gas to be higher... its 42 now... IIRC it was said to be 14 before... so maybe not much changed at all... 3x the MW, 1/3 the pressure.
Its more like a vacuum for engine Isp purposes... but I just tested out my duna lander, and it landed at 20 m/s on chutes... not bad.
It does seem that I come in faster... but maybe thats a different change... just like kerbin has less drag at lower speed/altitude, and more drag at higher speed/altitude?
Anyway, my winged lander was able to pull into a nearly flat glide, and slow down enough to pop chutes and do a tail sitting landing:

[img]http://i.imgur.com/dGz5JHr.png[/img]

My duna airplane (electric atmosphric propulsion) was also able to fly at a similar speed, although the engines produced less thrust due to the engine thrust being dependent upon atmospheric pressure, not density it seems.

[Pthigrivi]

Did some experimenting on Duna tonight, its really no problem. Did a really nice easy aerocapture at 22k. Drogues helped on the landing, but my guess is you wont need them with a shallow entry angle.

[Reactordrone]

Just landed a 1t probe on the southern ice cap. Didn't have any problems slowing down, with it reaching safe deployment speed before min deployment pressure had been reached and safely landing on 3 radial chutes. Just about to send off more ships so I'll see how a higher density craft reacts.