Parachute

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Revision as of 17:50, 11 December 2015 by Elembis (talk | contribs) (Usage: Repack by engineers only.)
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Parachutes are parts that when deployed slow down the speed of a craft in an atmosphere by creating drag. In career mode this allows to recover craft landed on Kerbin which returns funds.

While in theory it is possible to recover boosters like the Solid Rocket Boosters of the Space Shuttle with parachutes, it's difficult in practice because all craft outside the 2.5 km sphere around the controlled craft while in the lower atmosphere are getting removed. The timing has to be so that the circularization of the orbit with the main craft is not while the boosters are in the lower atmosphere.[1]

Usage

The options on a Mk16 Parachute

Parachutes are used on bodies with atmospheres such as Kerbin and Eve to slow the craft for a landing. The deceleration depends on both the mass of the craft and the density of the atmosphere. Therefore crafts that are either very heavy or land on bodies with thin atmospheres (Duna, Laythe) require either multiple parachutes or additional engines for a soft landing. Parachutes can also be used to aid with aerobraking to create additional drag. On the other hand, a heavier parachute part generates more drag than a lighter parachute. Parachutes can also be used to help stop space planes as they land.

Parachutes require a minimum air pressure to deploy, so they will work neither in higher parts of atmospheres nor in a vacuum (see Deployment). In addition, parachutes are cut automatically on the ground and can't be used, for example, to aid in slowing a landing aircraft once it's already on the runway. The part's mass isn't affected when the parachute is cut. A deployed parachute will cut automatically during descent if propulsion is used to increase vertical speed past zero.

A deployed parachute can also be cut manually (right-click on parachute and executing Cut Parachute). Once cut, they can be repacked on EVA by a level 1+ engineer. (To do this, right-click on the parachute and click Repack Chute.) Repacked Parachutes can be deployed like fresh ones, although not automatically via the staging sequence.

Pre-0.18 Mk16-XL in VAB/SPH
Pre-0.18 Mk16 in VAB/SPH

Before version 0.18 the image shown in the part selector of the VAB and SPH showed the parachute deployed. Since then all parachutes are shown stowed.

Parts

There are currently five options for parachutes.

Image Part Radial size Cost
(Funds)
Mass
(t)
Max. Temp.
(K)
Tolerance
(m/s)
Tolerance
(g)
Semi-Deployed
Diameter
Fully Deployed
Diameter
Semi-Deploy
Pressure
(atm) [Note 1]
Full-Deploy
Altitude
(m AGL) [Note 1]
Mk16 Parachute.png
Mk16 Parachute Tiny 422 0.1 2 500 12 50 0.8 20.7 0.04 1 000
Mk16-XL Parachute.png
Mk16-XL Parachute Small 850 0.3 2 500 12 50 2.5 51.2 0.04 1 000
Mk2-R Parachute.png
Mk2-R Radial-Mount Parachute Radial mounted 400 0.1 2 500 12 50 1.6 41.3 0.04 1 000
Mk25 Parachute.png
Mk25 Parachute Small 400 0.2 2 500 12 50 0.9 6.3 0.02 2 500
Mk12-R Radial-Mount Drogue Chute.png
Mk12-R Radial-Mount Drogue Chute Radial mounted 150 0.075 2 500 12 50 1.3 7.7 0.02 2 500
  1. 1.0 1.1 This setting is tweakable


Deployment

Parachutes semi-deploy at a specific atmospheric pressure. which is situated in different altitudes on different bodies (rough semi deployment altitudes are shown below). Contrastingly, full deployment occurs depending on height above ground, not pressure. Deployment altitudes and pressures of various parachutes can be found in the above table.

Both of these deployment settings are tweakable; Although, the semi-deployment pressures are set at minimum by default, so it's only possible to delay semi-deployment by tweaking. A delayed semi-deployment, along with prior areobraking, can avert broken parachutes due to high temperature on reentry

Semi-Deployment Altitude (m)
Image Part Eve Kerbin Duna Jool Laythe
Mk16 Parachute.png
Mk16 Parachute 44 226 20 004 10 689 126 238 25 146
Mk16-XL Parachute.png
Mk16-XL Parachute 44 226 20 004 10 689 126 238 25 146
Mk2-R Parachute.png
Mk2-R Radial-Mount Parachute 44 226 20 004 10 689 126 238 25 146
Mk25 Parachute.png
Mk25 Parachute 46 315 23 547 14 912 134 228 31 829
Mk12-R Radial-Mount Drogue Chute.png
Mk12-R Radial-Mount Drogue Chute 46 315 23 547 14 912 134 228 31 829

References

  1. Kerbal Space Program - Recovery And Reuse Tutorial in First Contract” on YouTube by Scott Manley