Dropping stuff from planes - how to do it?

[michal.don]

Hi guys,

I have several weeks of kerbal time before my station reaches Jool system, so I decided to do an Arctic mission on Kerbin, because I didn't visit the poles yet. My plan is to build a simple lab/base with a small rover, load it in an MK3-based plane and airdrop it near the north pole. However, I'm uncertain how to make sure the parachutes open after dropping the lab from the plane. Is it possible to set an "auto-deployment" on the parachutes? Can I / Do I have to switch to the lab and deploy the chutes via staging? Is it even possible to switch between planes in atmospheric flight? If so, do I have to stay within the 2,3 kms range? Or is there another, simpler way?

Thanks,

Michal.don

[Greenhornet553]

I am literally a noob at this but I may have a solution probably

Have you tried mixing the stage that decouples the lab and the stage that deploys the parachutes?

 

[Jaeleth]

You now have a 25km range. In the old days you'd have to fly real low and perform some aerobatics to keep within 2.5km rangs, but not anymore. You're safe.

 

Still, you should go near the ground, say, 100m above ground, if not for anything than making sure your cargo lands where you intend it too land.

Deploying chutes is very easy. Just attach your cargo to the plane with a separator, linear, radial, doesn't matters there are are lots of ways to do this. Insert chute deploy on the same stage than the separator... Bingo. Done!

 

worked many times on my missions on kerbin surface

 

 

[michal.don]

2 minutes ago, Jaeleth said:

You now have a 25km range. In the old days you'd have to fly real low and perform some aerobatics to keep within 2.5km rangs, but not anymore. You're safe.

Great, thanks for the info, It's going to be much easier than manouvering big a plane within 2,5 kms.....

However, when I tried decoupling AND deploying parachutes simultaneously, some explosive stuff happened - I guess it was caused by a collision between the chutes and the rest of the plane. Is there a way to make sure the chutes open later after the drop?

Anyways, thanks for your help guys,

Michal.don

[Greenhornet553]

5 minutes ago, Jaeleth said:

Still, you should go near the ground, say, 100m above ground, if not for anything than making sure your cargo lands where you intend it too land.

Deploying chutes is very easy. Just attach your cargo to the plane with a separator, linear, radial, doesn't matters there are are lots of ways to do this. Insert chute deploy on the same stage than the separator... Bingo. Done!

This guy said it, so it should work.

[Greenhornet553]

18 minutes ago, michal.don said:

Great, thanks for the info, It's going to be much easier than manouvering big a plane within 2,5 kms.....

However, when I tried decoupling AND deploying parachutes simultaneously, some explosive stuff happened - I guess it was caused by a collision between the chutes and the rest of the plane. Is there a way to make sure the chutes open later after the drop?

Anyways, thanks for your help guys,

Michal.don

What I used to do was release my cargo and then pitch-up so that my plane would only push the butt of my cargo and not explode.

So i suggest adding a radial decoupler which faces the direction of the cargo bay doors and adding sepratrons AND pitching-up. Anyways that's just me I'm pretty sure that there are different, much easier ways to do this but that's what I got.

 

[Jaeleth]

You can design your plane so that the engines are on both sides and the central rear of the plane (tail) is, say, a liquid fuel fuselage. Then attach the separator and the cargo there, much easier to drop than with the cargo bays. Beware of CoM change when you release the payload, though...

or you can carry it above the plane, with a radial separator or hard point, pitch up, go vertical, separate, and return to horizaontal flight. (Actually, just pitch up a little, the parachute will do the rest)

you can carry it below, like a bomb, but check if the landing gear has enough height for take off

or you can even, carry it inside the cargo bay with a docking port and land at the place, and unload it slowly And take off again

Edited December 22, 2015 by Jaeleth

[Reactordrone]

51 minutes ago, michal.don said:

Great, thanks for the info, It's going to be much easier than manouvering big a plane within 2,5 kms.....

However, when I tried decoupling AND deploying parachutes simultaneously, some explosive stuff happened - I guess it was caused by a collision between the chutes and the rest of the plane. Is there a way to make sure the chutes open later after the drop?

Anyways, thanks for your help guys,

Michal.don

The chutes have pressure switches so provided you're flying above the maximum deployment pressure ( I think 0.5 atmospheres) you can drop staged chutes and have them deploy when they're clear of the aircraft. Might have to do a test flight with a barometer to work out the altitudes/pressures.

 

ETA- just checked the Mk16XL and that can be set to 0.75 atmo so you can drop above 2km and the chute won't activate immediately (obviously keep an eye on the speed).

Edited December 22, 2015 by Reactordrone

[michal.don]

44 minutes ago, Reactordrone said:

ETA- just checked the Mk16XL and that can be set to 0.75 atmo so you can drop above 2km and the chute won't activate immediately (obviously keep an eye on the speed).

Thanks, Reactordrone,

this was exactly what I was wandering. I hope I'll be able to figure out the parachute settings, didn't try changing them yet.

Thanks,

Michal.don

[Snark]

4 hours ago, michal.don said:

However, when I tried decoupling AND deploying parachutes simultaneously, some explosive stuff happened - I guess it was caused by a collision between the chutes and the rest of the plane. Is there a way to make sure the chutes open later after the drop?

Yes, there is.

Parachutes have two "tweakable" settings that control how/when they activate.  These settings can be tweaked either at design time in the VAB, or in flight via the chute's right-click menu.

The first setting is "Min Pressure".  It's 0.04 atmospheres by default, but you can raise it to as high as 0.75 atmospheres (which is at an altitude of around 3000m on Kerbin).  This represents the minimum atmospheric pressure for the parachute to go to its "semi-deployed" state.  If the pressure is lower than this, then you can activate the parachute via staging, but nothing physically happens until you descend to where the pressure is high enough.

The second setting is "Altitude".  This is the height above ground level (not the absolute altitude that's shown on your instruments) at which the parachute goes from its semi-deployed state to fully-deployed-and-slowing-you-way-the-heck-down.  It's 1000 meters by default.

If you're having problems with things going kablooie if you decouple the lab and activate the chutes together, what you can do is this:

• Tweak the parachutes so that the "Min Pressure" is something much higher than the default 0.04.  A value of 0.5 is pretty reasonable, that corresponds to an absolute altitude of 4000 m or thereabouts, which is high enough that you have safe ground clearance in most places (as long as you're not in mountains), but low enough for convenience.
• Make sure that your airplane is flying higher than that level when you decouple the lab.  (An easy way to do this, if you're unsure which altitudes correspond to which pressures: put a barometer on your plane, right-click it, and choose "Toggle Display". It will show you the atmosphere percentage.  So for example, if you set your chutes' min pressure to 0.5, then it's safe to decouple the lab if the barometer says under 50.)

That's it.  The lab will decouple, and activate the chutes, but nothing will actually happen and the chutes won't do anything yet.  When the lab falls below the chutes' min pressure, they will semi-deploy, and then they'll deploy all the way as soon as the lab gets within 1000 m of the ground.

[michal.don]

1 hour ago, Snark said:

Yes, there is.

Parachutes have two "tweakable" settings that control how/when they activate.  These settings can be tweaked either at design time in the VAB, or in flight via the chute's right-click menu.

Thanks Snark,

your description really helps, it's clear to me now exactly what I should do to make my plan happen.

Thanks again,

Michal.don