How many parachutes?

[Sharpy]

Is there some kind of guideline or rule of thumb or a chart, how many parachutes per ton of reentry mass?

My approach so far was usually to slap four or six on the reentry piece and let the rest burn, but currently I'm planning a vehicle of at least 30 tons (probably more) that will need a bunch of them, and the question is "how big a bunch". There's not much difference between 4 and 6, but 40 vs 60 certainly is.

Edited June 17, 2015 by Sharpy

[DeMatt]

There is a parachute calculator at http://ksp.freeiz.com/; unfortunately, it hasn't been updated in nearly two years. I think it's good enough for an estimate, however, and if you put landing legs or wheels on, they can absorb (some of) the shock of landing.

[xtoro]

I've never thought of trying to calculate how many I need. I just go by what worked before and how fast I hit the ground. Also have to take into consideration speed, gravity and atmospheric density. When I think I have enough, I add two more. They get recovered anyways so no loss by putting more on.

[Prepper-Jack]

They get recovered anyways so no loss by putting more on.

To an extent. But, each has a fairly significant mass. Slapping 10 chutes on where 2 will do can really gut fuel economy.

[justidutch]

Part of the enjoyment of the game, for me, is finding all this stuff out on my own with test flights. I build my vehicle that I want to return to the ground, slap on some 'chutes, and build a test launch stage to lob it a few thousand meters up. Don't be lazy, test your ships!

[Brainlord Mesomorph]

Part of the enjoyment of the game, for me, is finding all this stuff out on my own with test flights. I build my vehicle that I want to return to the ground, slap on some 'chutes, and build a test launch stage to lob it a few thousand meters up. Don't be lazy, test your ships!

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Also here's a tip:

When I'm parachuting a long ship horizontally to the ground. I will add a couple of "balancing chutes" to each end. Then, after the chutes are fully deployed, if you happen to have to more (or less) fuel than you were expecting, the ship will be coming down at an angle.

Cutting one or both of the balancing chutes will fix this, and it will land horizontally.

[Foxdemon]

There is a parachute calculator at http://ksp.freeiz.com/; unfortunately, it hasn't been updated in nearly two years. I think it's good enough for an estmate, however, and if you put landing legs or wheels on, they can absorb (some of) the shock of landing.

Landing legs can absorb more then some of the impact. I once made a long ionbased mission to minmus (planethopping) for science and n reentry i realize i had no parachutes... So i put up my landinglegs and hoped for the best. Only ONE of the landinglegs broke due to landing on all legs simultaneously, the rest of the craft including the kerbal on board was intact. Landinglegs are op as hell.

[MaverickSawyer]

I use RealChute from StupidChris, as it allows you to not only set a number of parameters such as deployment altitudes, it also tweaks the parachute size to aim for a speed that YOU set for landing. Standard is 6 m/s, which is usually slow enough to keep stuff from exploding on landing.

[Venusgate]

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Also here's a tip:

When I'm parachuting a long ship horizontally to the ground. I will add a couple of "balancing chutes" to each end. Then, after the chutes are fully deployed, if you happen to have to more (or less) fuel than you were expecting, the ship will be coming down at an angle.

Cutting one or both of the balancing chutes will fix this, and it will land horizontally.

Use the CoM, Luke. Don't trust your instincts.

A tip for you, sir: build your landing stage in the editor, drain all your fuel from the tanks, place pairs of chutes equidistant from the CoM. Return fuel to tanks. Keep building.

And in case you knew that: I always try to drain my fuel to zero when landing on Kerbin on descent. It doesnt recover THAT many funds

[klesh]

Don't be lazy, test your ships!

That's about the size of it.

[Xannari Ferrows]

I don't really think it's a question of how many, but where to put them. The drag is modeled based on how much area the parachutes cover, rather than an equal amount for each parachute.

[Kryxal]

Also, remember that if all else fails, powered landings can deal with that last few m/s too many, and not-quite-enough chutes still slow you down quite a bit.

[11of10]

I usually use 1 smaller one per mass of a 1 kerbal capsule, and 1 large one per mass of 3 kerbal capsule.