Splashdowns: An underused method of landing?

[glen.mack]

I found some footage of the Gemini Splashdown testing, and tested it against the MK1 Command Pod.

 

I also tested splashdown as a viable means of unpowered landing without a chute.

Do you design craft deliberately for splashdown? Is it an underused side of KSP? Is it just " not glamorous"?

[Stratzenblitz75]

Ever since the water was changed in 1.05, I've preferred splashdowns to landing on the ground. You can get away with rougher landings, and thus, save on parts and mass. See my recent Eve mission as an example. I simply attached wings to capsule and landed it in the water. If I tried to land it land, then I would need landing gear or else explosions.

[wumpus]

Note that for engines much larger than 1.25, landing struts won't reach from the fuel tanks to the engine.  If you aren't interested/can't afford the scaffolding needed to build proper landing gear (or your rocket is too tall to land on all but the flattest areas), water landings are great.

That big old booster that makes up your last stage to orbit?  Slap on a few airbrakes, a few parachutes, and drop it in the drink (hopefully near KSC).  Don't bother with complicated landing gear or trying to find that absolutely flat plane near KSC, anywhere at sea will do.  You can probably do it with even less parachutes.

[Bev7787]

I have retrorockets fitted on my capsule so I can land anywhere I want, mainly either KSC or in the water

[RA3236]

As long as it is not a mountain range Ill land anywhere.

Edited January 20, 2016 by RA3236

[Rocket In My Pocket]

Ahh...the good ole' days when it was more dangerous to land in the water than on the land.

I think it's still so ingrained in me that the water is a liquid sheet of concrete death that I avoid it like the plague to this day.

I gotta start utilizing it now that it works right!

[Foxster]

Any rules of thumb here? Like, you can land something at 5m/s on land and 10 at sea?

[Snarfster]

My old-fashioned crew transport is generally aimed at the water just east of KSC. Works like a charm and still has 97% recovery value.

Don't know about the speed, I usually try to keep things under 6 m/s.

[Warzouz]

I use a lot of recoverable SSTO rockets. I always target KSC and land in water. Since 1.0.5, waters are more forgiving. I never destroyed any stage since.

NB : I recover stage up to 500tons.

 

[RizzoTheRat]

I've always preferred to splashdown my capsules, hadn't realised it used to be worse than landing on..er..land.  The main reason I tend to go for ocean is it's a big flat area with no annoying mountains to get in the way, I don't tend to be particularly accurate.

[Evanitis]

11 hours ago, Foxster said:

Any rules of thumb here? Like, you can land something at 5m/s on land and 10 at sea?

I have been playing with a seaplane lately. It feels the crash-tolerance stat matters here. I had no problem with structural parts and fuselages - the ones I checked had 50 m/s tolerance, and meant zero problem if I kept under that speed. Stuctural pylons and wings have 15 m/s tolerance, yet those never rarely broke while splashing down by 20-40 m/s. The main offenders I found are sensitive electronics - probe cores, reaction wheels. Those are listed with 5 m/s tolerance, and indeed I couldn't slow down enough to save them if they were used as structural parts. Moving them to a cargobay helped.

[Brainlord Mesomorph]

15 hours ago, Foxster said:

Any rules of thumb here? Like, you can land something at 5m/s on land and 10 at sea?

Actually I think it’s the other way around.

Coming down on landing struts you can land up to 10 m/s because that is the impact tolerance of the strut and nothing else touches the ground.

Coming down the water, everything touches the water!  So crash tolerance has to be for the weakest component usually below 5 m/s. So I usually aim for land.  If I’m building a a reusable vehicle that’s going to be coming in ballisticly (no wings or control services) then I’ll try to give enough parachutes it hits the ground below 5m/s.Just in case.

I think the only reason the United States used splash downs IRL is that we don’t have large empty tracts of land to bring spacecraft down safely.  We didn’t want a Mercury capsule landing on some farmer’s head.

 

EDIT: just saw that video in the OP.
Seems like a lot of work to go through to not use parachutes!* AAMOF, he had to use hyper edit to get that contraption into orbit. I don't see any practical application there.

*Speaking of a lot of work to not use chutes, I cannot understand why Elon Musk is so determined to land a rocket using LFO when wings and parachutes already exist.

Edited January 21, 2016 by Brainlord Mesomorph

[glen.mack]

15 hours ago, Foxster said:

Any rules of thumb here? Like, you can land something at 5m/s on land and 10 at sea?

I sort of pointed it out in the video, but maybe you missed it. You can land on the sea as fast as the crash tolerance of whatever hits the sea first is. The faster you hit the more drag is produced. As long as when the next part hits the water, you are then traveling below that parts crash tolerance, everything is still fine. You have various levels. Structural/cargo/passenger/plane parts between 50 and 80, (The Mk3 engine mount is a fav of mine) then everything else falls between about 6 and 20. (except the rover wheels, which go up to 150. hmmm. Might look into that.)

The reason sea is partly better in my opinion, is that you can much more easily control the angle at which you hit. I can bring the splashdown down safely on land at 65m/s. However this ONLY if the area is really flat or I get luck with the bounce. Sea works 99% of the time.

[Skorpychan]

I haven't quite gotten the hang of atmospheric guidance yet, so my landers land where they land. Be that ocean, land, mountains, whatever.

Honestly, I'm pretty bad at picking landing sites ANYWHERE, so I've gotten used to trying to bodge a proper landing. Splashdowns simply mean it's easier to not die.

[Aloriel]

17 hours ago, Rocket In My Pocket said:

Ahh...the good ole' days when it was more dangerous to land in the water than on the land.

You youngun's probably don't remember the time when it used to be more dangerous to land on the night side of the planet! Back in my day, you couldn't land in water, nor in darkness! It was land on land, or death (up hill, both ways)!

(For reference, back in version 0.9 or maybe it was 0.10, your craft exploded on contact with night side planet)

Now, git off my landing gear!

[Warzouz]

Splashing has one drawback : you can't use landing gears/struts to absorb ground shock. For example, I was very surprise to (mostly) survive a landing on Eve, hitting the ground at 50m/s (I only broke the engine). On Tylo, I remembered hitting the ground at 30m/s and broke nothing, even the ship was ready to take-off again (so quite heavy)

On water, if you splash at a higher speed, the lower par may survive, but the part above may not. I did few trials in 1.0.5 with may recoverable SSTO rockets. Even the Mamoths survived, the tanks above broke.

BUT, when you splash, you rocket will stay vertical much easily, and even it fall, it won't break as it would do in 1.0.4)

[Funky Schnitzel]

11 hours ago, Brainlord Mesomorph said:

*Speaking of a lot of work to not use chutes, I cannot understand why Elon Musk is so determined to land a rocket using LFO when wings and parachutes already exist.

I wondered this myself. Turns out, he wants the rocket to be able to be used as a primary stage (and recovered for reuse) anywhere in the solar system. Essentially, he's starting to build the infrastructure necessary for a Mars colony. 

[glen.mack]

13 hours ago, Brainlord Mesomorph said:

EDIT: just saw that video in the OP.

Seems like a lot of work to go through to not use parachutes!* AAMOF, he had to use hyper edit to get that contraption into orbit. I don't see any practical application there.

*Speaking of a lot of work to not use chutes, I cannot understand why Elon Musk is so determined to land a rocket using LFO when wings and parachutes already exist.

As a matter of fact? The whole thing weighs 7 tonnes. Maybe you have trouble getting 7 tonnes to orbit, or sending it on an interplanetary trajectory. It isn't an issue for me.

Don't claim things to be fact that you cannot possibly know.

[Temstar]

I design my craft for touchdown on land. Since dry landing is generally harder, if it can safely land on land it most likely can also safely land on water, therefore it's safe to land anywhere.

It's like how Apollo/Orion are designed for splashdown and Soyuz is designed for dry landing. Both can survive the opposite scenario just in case they miss.

[Yellowburn10]

Ever since I started playing more with water the best rules I made are:

1. Your impact angle. You can land more safely and faster on water going horizontally rather than vertically

2. Just don't be going in stupidly fast and you'll be ok

3. You shouldn't need to worry much as long as your craft was designed or prepared to land in water

 

 

[SpaceplaneAddict]

I have ditched some of my SSTO Spaceplanes without destroying anything (i.e RTG) and had:

Horizontal  velocity of 80m/s
Vertical veloicty 0.2m/s

[*Aqua*]

 

10 hours ago, Funky Schnitzel said:

22 hours ago, Brainlord Mesomorph said:

*Speaking of a lot of work to not use chutes, I cannot understand why Elon Musk is so determined to land a rocket using LFO when wings and parachutes already exist.

I wondered this myself. Turns out, he wants the rocket to be able to be used as a primary stage (and recovered for reuse) anywhere in the solar system. Essentially, he's starting to build the infrastructure necessary for a Mars colony. 

The first stage of the Falcon 9 weights about 20-something tons without fuel. You'll need an incredible large parachute for that. The rocket has an aerodynamic shape, it won't slow down in flight a lot by itself. That means the parachute must be deployed at high enough altitudes at very fast (supersonic) speeds.
Are there parachutes that can survive supersonic speeds while being pulled down by a 20-something ton weight? And would that parachute system be more reliable, lighter and cheaper than a proven rocket engine, guidance system and one ton of fuel? And does this parachute allow steering so that the rocket engine won't land in salt water?

[Brainlord Mesomorph]

1 hour ago, *Aqua* said:

The first stage of the Falcon 9 weights about 20-something tons without fuel. You'll need an incredible large parachute for that. The rocket has an aerodynamic shape, it won't slow down in flight a lot by itself. That means the parachute must be deployed at high enough altitudes at very fast (supersonic) speeds.
Are there parachutes that can survive supersonic speeds while being pulled down by a 20-something ton weight? And would that parachute system be more reliable, lighter and cheaper than a proven rocket engine, guidance system and one ton of fuel? And does this parachute allow steering so that the rocket engine won't land in salt water?

We have more advanced parachutes. Drogues can help you get subsonic. We have those big square parafoil things, you CAN steer them.  There are model rockets with various forms of retractable wings that deploy at Ap.  Scaled Composites has their "feather wing"

Musk is spending money and creating new tech. I was wondering why he wasn't improving wing and chute tech. 

My SSTO rockets (granted KSP, not IRL) have a tailfin/wing assembly to help steer them on the way down, have wheels, and are studded with enough parachutes for a fetish party. 100% recoverable on water or land.

 

11 hours ago, glen.mack said:

As a matter of fact? The whole thing weighs 7 tonnes. Maybe you have trouble getting 7 tonnes to orbit, or sending it on an interplanetary trajectory. It isn't an issue for me.

Don't claim things to be fact that you cannot possibly know.

I wasn't talking about weight, I was talking about size and drag. Granted I have not tested your design, but when I try to launch similar draggy, scoffoldy things, the rocket either flips over, or just breaks in half.

So that's 7 tons of scaffold vs >1 ton of chutes?

/still using chutes

12 hours ago, Funky Schnitzel said:

I wondered this myself. Turns out, he wants the rocket to be able to be used as a primary stage (and recovered for reuse) anywhere in the solar system. Essentially, he's starting to build the infrastructure necessary for a Mars colony. 

oh THAT's a reason.

[tutike2000]

I find that water is still a bad place to land, especially if you have components with low crash tolerance (Hitchhiker module).
Landing on ground at 10 m/s is fine, as long as you have landing legs. Splashing into water will kill your Hitchhiker and the kerbals inside

[Nightshift83]

Might be Hitchhiker specific problem, killed like 12 tourist in one landing, which I repeatedly tried. But maybe it was that the mass of the whole thing pushed it too far underwater (is that even a problem, never done any submerged stuff ?).

Accepted the blame since the whole mission had allready net me so much money with a single Kerbin-Mun-Minmus tour and the pilot survived in the upper stage.

But the hint to go more horizontally might proof usefull next time!