Difference between revisions of "Parachute"

Revision as of 19:11, 19 December 2015

A Mk1-2 Command Pod hanging on a Mk16-XL Parachute

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.

Staging icons

Changes were made to the staging icons in version 1.0.5. The staging background colour now indicates whether or not it is safe to deploy the parachute, being grey-green at under 250 m/s and red at any higher speed. The foreground colour (i.e. the colour of the parachute itself) indicates the state of the parachute, starting at white (unstaged/undeployed) and running through cyan (released but insufficient pressure to semi-deploy), yellow (semi-deployed), green (fully deployed) and red (destroyed).

A cyan parachute on a red background is therefore a highly undesirable combination since it means that the parachute has been released at too high a speed and will be destroyed as soon as air pressure is high enough for semi-deployment.

parachute icons in 1.0.5. From left to right; at rest; not safe to deploy; released while unsafe and insufficient pressure; destroyed; safe to deploy, semi-deployed, fully deployed

Parts

There are currently five options for parachutes.

Image	Part	Radial size	Cost ()	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	Tiny	422	0.1	2 500	12	50	0.8	20.7	0.04	1 000
	Mk16-XL Parachute	Small	850	0.3	2 500	12	50	2.5	51.2	0.04	1 000
	Mk2-R Radial-Mount Parachute	Radial mounted	400	0.1	2 500	12	50	1.6	41.3	0.04	1 000
	Mk25 Parachute	Small	400	0.2	2 500	12	50	0.9	6.3	0.02	2 500
	Mk12-R Radial-Mount Drogue Chute	Radial mounted	150	0.075	2 500	12	50	1.3	7.7	0.02	2 500

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	44 226	20 004	10 689	126 238	25 146
	Mk16-XL Parachute	44 226	20 004	10 689	126 238	25 146
	Mk2-R Radial-Mount Parachute	44 226	20 004	10 689	126 238	25 146
	Mk25 Parachute	46 315	23 547	14 912	134 228	31 829
	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