Difference between revisions of "Mk25 Parachute"

Revision as of 02:02, 31 July 2016

Mk25 Parachute
Parachute by Found lying by the side of the road
Radial size		Small, Radial mounted
Cost	(total)	400.00
Mass	(total)	0.200 t
Drag		0.1
Max. Temp.		2500 K
Impact Tolerance		12 m/s
Research		Advanced Landing
Unlock cost		3 500
Since version		0.18
Part configuration		parachuteMk25.cfg
Semi-Deployed Drag		4
Semi Deploy Min Pressure		0.02 atm
Fully-Deployed Drag		170
Full Deployment Altitude		2500 m AGL
Max. Temp.		1600 K
Testing Environments
On the surface		No
In the ocean		No
On the launchpad		No
In the atmosphere		Yes
Sub-orbital		No
In an orbit		No
On an escape		No
Docked		No
Test by staging		Yes
Manually testable		No
Packed volume		900 l

Usage

This parachute is eqivalent to two Mk12-R Radial-Mount Drogue Chutes. Drogue chutes exist to slow a craft down just enough to safely open a standard parachute. They differ from standard parachutes by activating at a much higher altitude and speed, and generating more drag when not fully deployed. They have much less drag than the others when fully deployed, often not enough to prevent a craft from crashing on the surface. That means that in addition to this parachute a second method of braking is always required.

All parachutes currently have four activation stages: unactivated, activated, partial deployment, and fully deployed. A parachute becomes activated when it is staged, or when the "deploy" button is clicked and the craft is in flight, or it is triggered through an action group - the parachute's icon will turn light blue or green, but nothing else will happen at that point. Parachutes can be activated only on a craft that has some kind of command unit, so it is sometimes important to activate them before they get decoupled from the main craft.

A parachute will automatically go into partial deployment mode if it is activated and then descends below the atmospheric pressure set in its tweakable values. It will automatically go into full deployment if it is already partially deployed, and reaches an altitude above the terrain that is set in the tweakable values.

Right-clicking on the parachute (or looking at the parachute's icon) will give you information on whether the parachute is likely to survive being partially or fully deployed at the craft's current speed. On Kerbin, this parachute can always safely fully deploy at a speed of around 500 meters per second. Safe partial deployment speeds are quite a bit higher, and depend on atmospheric pressure.

In reality, any drogue chute should fully deploy before a regular parachute even tries to partially deploy. However, the maximum full deployment altitude for the drogue chute is currently 5000 meters, which is probably below the point where you want to partially deploy your regular parachutes.

Usage Details

In the current version attempting to activate parachutes and a decoupler on the same stage seems to be dangerous. Sometimes the decoupler activates first and then the parachutes do not activate at all.

It is almost always useful to tweak the tweakable values on these parachutes.

Pressure

The default .02 partial deployment pressure corresponds to an altitude of around 21000 meters on Kerbin. You need to know through testing whether the atmosphere will have slowed your craft down to 500 or 600 meters per second by this point, to make it safe to partially deploy the drogue chute. If it will take a little longer to slow to a safe speed, then increase this pressure value accordingly.

Altitude

The default full deployment altitude value for this parachute is 2500 meters, which is just wrong (basically, it's a bug). Always increase it all the way up to 5000 meters - even higher (like 10000) would be better, in future versions.

Product description

Changes

0.18

• Initial release