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Grand Ship Builder

Is it possible to land using drag alone? (without parachutes)

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Yes, the things you need are called wings and wheels.

 

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4 minutes ago, bewing said:

Yes, the things you need are called wings and wheels.

 

1. Wheels use friction, not drag.

2. I said drag ALONE. Not friction, force, or anything else.

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5 minutes ago, Grand Ship Builder said:

1. Wheels use friction, not drag.

2. I said drag ALONE. Not friction, force, or anything else.

There is no such thing as drag alone. Everything in an atmosphere experiences a full range of aerodynamic forces, including lift.

If you mean "can I make a completely passive reentry vehicle that has minimal lift and will survive impact with the ground", then no. Anything that comes in on a pure ballistic trajectory will impact at over 300 m/s and will be completely destroyed. Subsonic drag goes as velocity squared, which means there really isn't very much of it -- usually not even enough to counteract gravity.

 

 

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You could try the inflatable heat shield... it slows down things an awful lot.  With a high crash-tolerance part like the Mk 3 crew cabin, you can at least get close. I just tried it and landed at about 60 m/s... broke a nosecone but the cabin survived.  So certainly in the survivable range with a little lithobraking.

Of course, that heat shield is pretty much a parachute in all but name.  It's probably lost cause for a more typically-shaped spacecraft (unless it's a plane, as noted above).  

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Or you can use a bunch of air brakes, those things have a ridiculous amount of drag.

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If a probe core, some surface solar panels and an M700 scanner produce no lift yes.

You do have to go to Eve to do it though.

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I noticed that the OP was really adamant that we discuss "drag ALONE", so I'd like to add my 2 frictionless cents.

When you impact the ground, and you vehicle slows down because of this impact, that is certainly not called "drag". If anything, the normal force is more closely related to lift.

Also, drag is a function of velocity squared (as @bewing said above) , so it will rapidly approach zero as your speed is reduced. You cannot reduce the airspeed of any vehicle to zero by drag alone (in KSP we have no wind - if you add wind, you could make your ground speed zero by drag alone).

So, in my opinion, the answer is NO.

Edited by Magzimum

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13 hours ago, Grand Ship Builder said:

Can you land using drag alone? Parachutes don't count here.

Yes, absolutely!  :)

It's not even all that difficult.  The key is, 1. have a lightweight, high-drag craft (so its terminal velocity isn't too high), and 2. have something really heavy-duty and impact-resistant to land on.

For example:  The larger aircraft landing gear have a ridiculously high impact-speed tolerance, and also strong shock-absorbing springs.  This assertion may sound counterintuitive to people who've gotten frustrated with "why do my landing gear keep exploding when I try to land."  But what's killing the gear in that case isn't the speed touching the ground-- it's the the plane's inertia crushing the gear, because the gear is too small for the vessel.

If you do it the other way around-- i.e. put landing gear on the craft that's way too big for the craft-- you'd be astonished with what you can get away with.  For example:  Try making a small lightweight vehicle, built around a Mk1 command pod or lander can.  Then, instead of landing legs, give it 3 or 4 of the largest-size aircraft landing gear attached around it with radial symmetry.  Drop it out of the sky without parachutes, but with the landing gear deployed.  As long as it lands with the gear facing downwards, it'll do just fine.  (You may need to tinker with the spring/damper settings on the gear to prevent bouncing.)

So all you need to do is for your craft to be reasonably lightweight and high-drag and it's easy to do.

I have also heard (though haven't tested it myself) that undeployed fairings are also freakishly impact-resistant, so if you can build a craft that hits the ground fairing-first, I hear that can work well, too.

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You can land with *"drag" *cough*  *"Lift" *cough *"Aerodynamics"  only.
It's called a airplane.

Getting to a full stop through aerodynamic braking however is not possible. Maybe this is what you wanted to know? Maybe you wanted to do it with a capsule? You can't.
 

There's a phase in between surface touchdown and "Lift" and this phase is called stalling.
So unless it has no way to stop otherwise by rolling on gear your gonna crash after the stalling phase. 

Maybe you can build a custom fixed parachute or heatshield made from wing parts. If you use enough wing parts and shape it conically so that it is guided you may put some small cargo in and let it airdrop. The bottom parts probably will still break. Things tend to fall not much slower then 15-20 m/s as a wing piece. So adding cargo (that which your trying to land) will make it sink even faster.
And average crash tolerances are half the speeds I just mentioned. So unless you want to sacrifice bottoms parts or put landing gear on the bottom your not going to use a method differently then airplane land or parachuting. This will make the design unnecessarily complicated and lifting custom build airfoil on a rocket creates quite a lot of drag. So from a whole gameplay/career, science and funds efficiency point of view your better of landing things the old fashioned way.

EDIT: What Snark said about the landing gear. I do find it a bit out of context how they survive enormous impact loads. You really can land things at 40 m/s using gears as shock absorbers. But using gears as absorbers basically means you can land anything. Probably not in the case of a capsule hitting the ground at 300m/s, but who knows, one should try...

Edited by Helmetman

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48 minutes ago, Helmetman said:

Getting to a full stop through aerodynamic braking however is not possible.

Technically true, in the sense that you can't slow to a halt in midair with drag alone.  However, I don't think that's what the OP was asking.  What he was asking is, can you slow enough with drag so that you can land undamaged without parachutes.

And that's definitely doable.  With a lightweight, high-drag ship, it's easy to get the terminal velocity down to just a few dozen m/s.  And it's possible to build an impact-resistant ship that can withstand a "landing" at those speeds.

48 minutes ago, Helmetman said:

Maybe you wanted to do it with a capsule? You can't.

Sure you can.  Just attach some heavy-duty landing gear to the capsule (as I describe above), and it can fall out of the sky and land unharmed.  :wink:

48 minutes ago, Helmetman said:

What Snark said about the landing gear. I do find it a bit out of context how they survive enormous impact loads.

How is it "out of context"?  Seems to me that it's perfectly in context-- the OP wants to know "how can I survive landing without parachutes", and that's exactly perfectly a thing that enables that.

48 minutes ago, Helmetman said:

You really can land things at 40 m/s using gears as shock absorbers.

Quite a bit faster than that, actually.  :wink:

48 minutes ago, Helmetman said:

But using gears as absorbers basically means you can land anything.

Pretty much, yeah.  But the question wasn't "is it elegant" or "is it an 'exploit'", but rather "is it possible".  And the answer to that question is "yes".

49 minutes ago, Helmetman said:

Probably not in the case of a capsule hitting the ground at 300m/s

Not that fast, no.  But it's pretty easy to build a ship with a terminal velocity well under 100 m/s, and that's plenty slow enough for a landing-gear landing, if the gear's beefed up enough.

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13 hours ago, Grand Ship Builder said:

1. Wheels use friction, not drag.

2. I said drag ALONE. Not friction, force, or anything else.

The impact of the whells with the ground is just a particular 'kind of drag'. We don't call it that way but is just another resistive force that appears when we try to pass thru that medium. Wheel are particularly usefull for this stuff because it will have considerable less friction with ground than other parts and will slide instead of bouncing, so it's less likely yo your craft to tumble and hit the ground with a less resistant parts. Off course for this be most effective you need to land at a shallow angle so, either landing horizontal or at a slope.

If you want to land vertically in a flat surface that is much less likely.  You need a lot of crossectional area with very little  mass. Excluding parachutes our best bets would be wings, control surfaces and structural panels monted perpendicular to the airflow. That looks like a horrible bet at this point.

BTW aerodynamic drag is also a FORCE caused by the FRICTION of a moving body with the surrounding air. Words have power, be careful. 

 

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5 hours ago, Snark said:

Technically true, in the sense that you can't slow to a halt in midair with drag alone.  However, I don't think that's what the OP was asking.  What he was asking is, can you slow enough with drag so that you can land undamaged without parachutes.

And that's definitely doable.  With a lightweight, high-drag ship, it's easy to get the terminal velocity down to just a few dozen m/s.  And it's possible to build an impact-resistant ship that can withstand a "landing" at those speeds.

Sure you can.  Just attach some heavy-duty landing gear to the capsule (as I describe above), and it can fall out of the sky and land unharmed.  :wink:

How is it "out of context"?  Seems to me that it's perfectly in context-- the OP wants to know "how can I survive landing without parachutes", and that's exactly perfectly a thing that enables that.

Quite a bit faster than that, actually.  :wink:

Pretty much, yeah.  But the question wasn't "is it elegant" or "is it an 'exploit'", but rather "is it possible".  And the answer to that question is "yes".

Not that fast, no.  But it's pretty easy to build a ship with a terminal velocity well under 100 m/s, and that's plenty slow enough for a landing-gear landing, if the gear's beefed up enough.

@Snark I have to admit, I'm biased not to use landing gear as a solution because I find it very OP.

So it is possible, okay, got it!
I know the word "possible" is in the OT, and that there draws the line, sorry for misreading it.
I understand your point, now understand mine.

I'm not the kind of guy who wants to give advice on a very few loophole solutions this game has like using landing gear. And if the question is to land on "drag" alone, I interpret it as "drag" alone.
Also the question is landing using drag only without parachutes. So my assumption is that the OP means something that can decelerate below crash damage tolerant speeds without parachutes. Rather then using this magic part that can absorb 300 kp/h in a instant of impact with every part and crew member surviving.

If that's the solution you'd hardly need drag. Just a little to stay below a critical impact speeds for the gear to survive. In which case it's not even a main topic of drag anymore. Since landing gear absorption is far from braking by aero drag only.
Maybe I shouldn't have spoken as I did in my  previous reply considering the Bias I mentioned. The straight answer to use landing gear is the straightest answer, period. But the method I find wrong. 

I know stuff on a series of landing gear can survive much harder loads then 40m/s. The number is just a example of my personally added up average of impact crashes while surviving using landing gears, although I never intended to test the max loads tbh. If 100m/s is a achievable max then using it for braking makes this solution far away from landing using drag alone. It's landing using drag and space alien suspension and impact absorption techniques. If you allow that in your answer then sure, it's a good answer. Just not within my ballpark of methods I would use. 

And I think it's me answering through my own facts and "experience" what best can be done.
My apologies towards the statement where I said it can't be done. I have to admit that was a little silly. I will not make such assumptions on the bias of my own implemented limitations and assume the person in front of me wants all options on the table.

As for the context of this thread. It's landing by drag alone. Landing gear absorbing up to 100m/s is out of the context of air drag deceleration. So I'm not sure how I didn't make a point there. The only thing you could convince me is that you context it differently. But you'll have to explain yourself on that one because this is how I put it into context.

Not sure how it can be viewed many other ways, but I like to be told in a decent manner if I'm hellishly wrong.

 

Edited by Helmetman

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