How to have a plane drop a probe to the surface of Kerban which persists

[GarrettKajmowicz]

Greetings!

In a fit of stupidity, I accepted a contract which, among other things, requires taking pressure readings at the surface of Kerbin - over the ocean.

In an attempt to do this in a resource-efficient manner, I have one of my non-space planes fly over the location and "bomb" it with an instrument package. The plane itself is fairly uninteresting, with a Mk2 cockpit and staffed with 2 kerbals, 1 of which is a pilot. The instrument package is an OKTO core with a barometer, Mk16 parachute, and a battery. They are attached together using a mini docking port on the plane as a retaining location. I have an action group set up which deploys the parachute and decouples the docking port.

During my attempts, I'd fly over the location at ~700m. Once I enter the correct zone, I'd hit the action group, the probe would decouple with the parachute extended, and I'd put the plane into a gentle climb. Then I'd quicksave the game.

If I kept focus on the plane, I can fly back, land, and recover without incident. However, I'm unable to switch to the probe (even through the tracking station) to finish that part of the contract.

If I switch focus to the probe after detatching, the probe falls, gently lands in the ocean, and I'm able to grab the data I need. I can recover the probe. However, the tracking station doesn't show my plane.

I can easily switch between the plane and the probe right up until the 2.5 km boundry is passed, at which point no luck.

Is there any way to get both of these to persist?

Edited January 8, 2015 by GarrettKajmowicz
Now answered.

[Anquietas314]

Not in stock, sorry. The game deletes anything not controlled by you that's flying below ~23km in the atmosphere and outside physics range (2.5km) (at Kerbin - on other planets its where atmosphere pressure is >= 0.01). You can use the Flight Manager for Reusable Stages mod to do what you want though

[Mitchz95]

Just fly low enough that the probe hits the water before you fly out of physics range.

[Anquietas314]

Just fly low enough that the probe hits the water before you fly out of physics range.

Well, that too, but that requires a fair bit of piloting skill to have the probe drop quickly enough before you fly that far away and survive the impact (deploying chutes while in the bay is a very bad idea... for obvious reasons ).

[Jimbimbibble]

You can set the chute to deploy at 50m altitude. It should only take a couple seconds to splash down.

[Anquietas314]

You can set the chute to deploy at 50m altitude. It should only take a couple seconds to splash down.

The thing is, even with the chutes half-deployed, at that altitude it could very easily tear the plane to pieces or cause it to nosedive.

[Mitchz95]

Pack a bunch of wings onto the plane so you don't need to go as fast. That plus the aforementioned setting parachutes to 50m should be enough.

[Reactordrone]

You could find out the air pressure at the altitude you want to fly at and set the pressure switch on the chute to activate only at a higher pressure than that.

Just tested and you have to be above 4000m since the chutes pressure can only be set to a maximum of 0.5 but it's do-able, just needs a lot of circling around until the probe lands. Interestingly the chute doesn't disappear after landing so you need to listen for the splash.

Edited January 4, 2015 by Reactordrone
added test results.

[Anquietas314]

Pack a bunch of wings onto the plane so you don't need to go as fast. That plus the aforementioned setting parachutes to 50m should be enough.

I did some testing, and the success of that seems to depend heavily on what exactly you're dropping and how you're dropping it. Bigger cargos tend not to work out very well, especially if you're going reasonably fast. Small cargos at lower speeds (~50m/s) seem to be reasonably safe - the payload typically clears the bay before it collides with the rest of the plane, assuming you drop the payload from the front of the bay. If it's dropped from the back, it may or may not leave the bay dependent on speed, angle of attack required to maintain flight at that speed, etc. Chutes used are also a factor :/

[Kryxal]

I did something similar once, I think I used decouplers. It worked out fairly well if I didn't lose range.

[dryer_lint]

You should be able to fly pretty low and still have chutes slow it down. Chutes are ridiculously powerful

[Captain Sierra]

I did something similar once, I think I used decouplers. It worked out fairly well if I didn't lose range.

This.

Decouplers, especially radial mounted to the bay ceiling, are your friend. The ejection force on a light probe will clear it from the bay before anything bad can happen.

[NightOwl07]

You can fly at ~1km altitude, drop payload, and circle within range until the probe lands. That way you don't have to worry about chute deployment much and it can just open at the standard 500m.

[GarrettKajmowicz]

I took the approaches suggested here and achieved a workable solution. I flew at about 100m altitude with the chutes set to open at 50m. An action group to release and trigger the parachute. I was able to fly back to base and later on switch to the probe to complete the contract.

Many thanks to those provided feedback.

[^^artin]

I currently accepted a similar contract.

First I thought, something must have went wrong when this contract has been generated ! Did not even thought about dropping a probe by now.

I will give this a try too, but I'm not very optimistic about the outcome !

[kahlzun]

Yeah, these contracts are the worst.

[MarvinKitFox]

Just build your plane to have VTOL, water-landing ability.

My plane had a pile of parachutes, allowing it to land safely in water.

Then Bill climbs out, collects the science stuff, and re-packs the parachutes. (Bill is my engineer)

I have a simple probe on the plane's nose, to assist Bill with piloting trivia.

To take off, I have two jet turbines mounted in the wings. *just* strong enough to lift the plane, once a drop of fuel has been burned off, and pretty much exactly along the CoM

Once I get to 100m alt, I throttle up my turbojets and switch off the hover-jets soon as I have sufficient forward momentum.

P.S.

This designs also makes those normally-painful mountaintop surveys a doozle.

Fly there like a plane, land like a paratrooper, and take off like a vacuum cleaner.

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Edited February 7, 2015 by MarvinKitFox

[Commander Jebidiah]

fly at 100m and drop the probe and make sure the parachute deployment height is 50m this way it will slow enough at only 10m and land before you get out of physics range

[Tank Buddy]

Just circle the probe as it descends to the surface. Stay within 2.5 Km.

[juvilado]

As i read from the post, the problem is related to bad programming of the game, isnt it? in a "normal" dituation, there wouldnt be any problem with that, you just launch the bomb with parachute and return with the plane, then go to space center and go to the splashed probe. This should be an issue to report at bugs dont you think so?

[Alshain]

As i read from the post, the problem is related to bad programming of the game, isnt it? in a "normal" dituation, there wouldnt be any problem with that, you just launch the bomb with parachute and return with the plane, then go to space center and go to the splashed probe. This should be an issue to report at bugs dont you think so?

No, it's not bad programming. It is done by design. The game can't keep every craft you launch in memory so it unloads them when you leave their immediate area (2.2km). When unloaded they go "on rails" meaning their orbit is fixed and never-changing (with exceptions, planetary encounters will still affect it). If its orbit falls too far within the atmosphere, the game can't leave it on rails so it just removes it.

Edited February 8, 2015 by Alshain

[^^artin]

Mission accomplished now.

I used 2 probes based on that boxy core thingy. For lateral montage to an radial decoupler I used an empty, tiny monopropellant tank, as well as one MK16 chute(set to 50m altitude), the pressure probe itself and some solar panels to keep it alive. Dropping it, as suggested, from a height below 100m to the sea. Then, at some distance (to get some time), I turned the plane, heading towards the probe again and tried to keep it at a most stable height below 100m. Below 100m I was able to directly switch to the probe by hitting the "accent key" (bracket key) when I was close enough. As I went higher I got a message like "Not able to switch to vessel while in atmoshere" but below 100m switching to close vessels worked for me.

Then I performed the pressure readings and switched back to the plane. Luckily that worked pretty well without crashing the plane to the sea.

Edited February 9, 2015 by ^^artin