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grafdog1138

Dropping Probes with Active Parachutes from a Plane

Question

Ok, this is a really complicated question, but I'll do my best to make it clear.

I've built myself a plane with a downward facing cargo bay (called henceforth carrier). It's purpose is to carry a few probe cores, outfitted with parachutes, a small battery, and some science gear, and drop them into different biomes for data collection (called henceforth pods). The idea being I can record data and collect science from many biomes with fewer missions launched, and also very quickly, since the carrier pushes right up to the edge of mach 1, fully loaded.

So far so good. I fly off with one pod in the carriers belly, and an action group to detach the pod, deploy its chute, and turn off its hibernation all at once. I let it go at about 3,000m, everything looks peachy. I can't switch to the probe, since I'm flying in atmosphere, so I watch its altitude and speed from map view. It holds at about 175m/s all the way into the ground.

After much tinkering with drogue chutes, differing altitudes and states of probe hibernation, I decide that what needs to happen is I need my control to follow the pod when it detaches instead of the plane. That way I can see what's really happening with the parachutes, and once its landed I can switch back to the plane and keep flying. I had toyed a little with the Stratolauncher (stock), so I figured this would work well. I converted all my action groups into a staging setup, since that's how the Stratolauncher (stock), is set up, and I thought it would work. Same deal as before.

How do I get this to work? How can I designate to the editor that I'd like the staging to follow the probe pod out the belly, instead of the plane all the way? Or is there another solution I'm not seeing?

I'd include the .craft file of the carrier as it stands right now, but I'm not sure how to attach a .craft. I'd appreciate a concise explanation of that as well if you feel the need to see the plane.

Thank you!

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I believe that you can reroot the craft so that the Octo or similar probe core is the main control point. You just need to say 'control from here' to fly the plane normally.

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Oh... so the probe core has to be the first part down, is what you're saying? And thus I couldn't drop two from one plane?

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yeah, just select control from here on the probe before you drop it.  The big problem you're going to run into is that KSP despawns anything that is not attached to the controlled object if it gets more then 2.3 km away and is in midair.

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I think I've tried that control from here bit before, but I'll give it another shot... and the despawning only occurs with debris and things, not crafts with active probe cores, right?

EDIT: Yeah, no dice with hitting "control from here" mid-flight... gonna try putting the pod's core down as the first part and see if that works.

Edited by grafdog1138

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That wasn't necessary for me with my science bombers as I call them.  I just needed to stay nearby.  I also set the deployment so they would fully open right away.  You can switch while flying, especially to something else that was just released from your current ship, I do it all the time for stratosphere launches from carrier ships.  But the distance for switching is greatly reduced.

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Haven't had any problems dropping science buckets.

screenshot87_zpsgj7ftuok.png

The payload separation used an action group for decoupling and chute deployment, although I left the cores active with torque turned off.

 

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Whenever I try to switch to one of the pods I've dropped, it says that I can't switch vessels while flying in atmosphere. :(

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1 hour ago, grafdog1138 said:

Whenever I try to switch to one of the pods I've dropped, it says that I can't switch vessels while flying in atmosphere. :(

Try getting closer to them.  Roughly 300 meters.

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3 hours ago, grafdog1138 said:

and the despairing only occurs with debris and things, not crafts with active probe cores, right?

No, it happens with anything. If you get out of physics range while something is in atmosphere and below 25km altitude it gets deleted forever. Kerbals, planes, science packages, anything.

 

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I'd suggest to stay in control of the carrier, drop the pods, return and recover the carrier and then proceed to the instrument reading. Also, I consider the cargobay a luxury, decouplers attached to the fuselage or wings can do the trick.

 

Alternatively, if you don't mind mods:

 

 

Another possible approach its using some mod that automagically run science experiment and just briefly touch the desired  area for the 'landed' science. But for this you also need to be confident enough you can avoid crash when trying to touch&go.

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I believe you're simply going too fast. The standard chutes are only safe to deploy at speeds up to ~250m/s; any faster than that, and deploying them will see them ripped right off (which I'll bet you is in your flight log). So when you hit that action group, you're effectively dropping a rock into the ground. (Drogues can be deployed at about double that speed, but I doubt they'd provide enough drag to slow down your pods enough to touch down safely.)

I was running into this when I was trying to build recoverable boosters, and instead of watching them float gently to the ground they'd just go into free-fall; took a while before I just happened to notice the message on my screen.

What you need to do, since you can't switch control while in flight, is slow your carrier down to under 250m/s, and watch the chutes' staging icon: When it's a white chute on a gray background, it's safe to drop your pod. (If you could switch control, you could drop the pod and either pop a drogue until it's safe to pop a main chute, or cross your fingers that you'll slow enough to pop a main before you start lithobraking.)

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3 hours ago, Kromey said:

I believe you're simply going too fast. The standard chutes are only safe to deploy at speeds up to ~250m/s; any faster than that, and deploying them will see them ripped right off (which I'll bet you is in your flight log). So when you hit that action group, you're effectively dropping a rock into the ground. (Drogues can be deployed at about double that speed, but I doubt they'd provide enough drag to slow down your pods enough to touch down safely.)

I was running into this when I was trying to build recoverable boosters, and instead of watching them float gently to the ground they'd just go into free-fall; took a while before I just happened to notice the message on my screen.

Not the case since 1.2 when parachutes got the (default) option "deploy when safe". Just to be sure I straped a 'pod'(extructure, probecore, parachute and decoupler) in a fast plane, get up to unsafe speed for deployment and staged (decoupler+parachutes), as expected parachutes become 'armed' at decoupling and deployed once the pod slowed enough.

Still a good idea to slow down to easily maintain the pod in physical range until touchdown, but irrelevant for parachute deployment.

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21 hours ago, grafdog1138 said:

Whenever I try to switch to one of the pods I've dropped, it says that I can't switch vessels while flying in atmosphere. :(

This may help: 

 

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16 hours ago, Spricigo said:

Not the case since 1.2 when parachutes got the (default) option "deploy when safe".

I'll have to look into this. It was just this past weekend that I was seeing messages about chutes being destroyed when I was decoupling+parachuting boosters from my rockets at "unsafe" speeds. Maybe that default option somehow got turned off for me? Or maybe not an option yet in my still-early career mode?

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Wow, I really appreciate all this feedback! This seems like a pleasant, informed, helpful community. Thank you all!

Not sure where to start replies, so all just give a little update as to my design and thought processes...

I rebuilt the carrier starting with the probe core as the first piece. It took a while and was extremely bothersome, but I got it done. This method seemed to work pretty well; upon dropping off the pod, it was targeted and the parachutes deployed perfectly. I actually had been using at least one drogue chute in all my designs, being aware that the high flight speed would shred a normal chute. So all in all the current setup does what it says on the tin.

Slight issue though. For all my tests, I've simply took off, pulled an Immelman (which results in a westward heading), and deployed the pods right out on that open field of grasslands behind KSC. No point in flying for a long time only to find out I overlooked something stupid. So when I dropped the pod, the plane had nobody controlling it, and by the time I made land the plane was gone. I'm not sure if it despawned or crashed into the mountains out back of KSC. Suddenly, the physics range extender mentioned by @DoctorDavinci is tempting, despite my potentially obtuse adherence to a strict vanilla purity until I get my feet a little better.

Thank you all again, you're an extremely helpful community for newbies like me.

P.S. Quick question @DoctorDavinci, will this mod you mention increase lag? I'm not running KSP on as robust a computer as I might like.

Edited by grafdog1138
Forgot P.S.

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34 minutes ago, grafdog1138 said:

I rebuilt the carrier starting with the probe core as the first piece. It took a while and was extremely bothersome, but I got it done.

This doesn't help you now that you've already re-built it, but you didn't have to do that. 

A much easier and quicker way would have been to use the 're-root' tool. It's meant for exactly the thing you wanted to do. Press 4 on the keyboard (or click on it's icon, the fourth button in the top left corner of the screen, just to the right of the parts list). Then click anywhere you want on the craft, then click on the part that you want to be the new root. That's it. 

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49 minutes ago, FullMetalMachinist said:

This doesn't help you now that you've already re-built it, but you didn't have to do that. 

A much easier and quicker way would have been to use the 're-root' tool. It's meant for exactly the thing you wanted to do. Press 4 on the keyboard (or click on it's icon, the fourth button in the top left corner of the screen, just to the right of the parts list). Then click anywhere you want on the craft, then click on the part that you want to be the new root. That's it. 

:mad: What?!? Drat... well, I guess this is how you learn. Thanks! XD

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1 hour ago, grafdog1138 said:

Quick question @DoctorDavinci, will this mod you mention increase lag? I'm not running KSP on ass robust a computer as I might like.

Not sure ... only one way to find out :wink:

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21 hours ago, Spricigo said:

 

I'd suggest to stay in control of the carrier, drop the pods, return and recover the carrier and then proceed to the instrument reading. Also, I consider the cargobay a luxury, decouplers attached to the fuselage or wings can do the trick.

 

Alternatively, if you don't mind mods:

 

 

Another possible approach its using some mod that automagically run science experiment and just briefly touch the desired  area for the 'landed' science. But for this you also need to be confident enough you can avoid crash when trying to touch&go.

Yeah, I know the cargo bay isn't technically necessary, but what can I say? It was a new part I got, and it looks wicked this way :cool:

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On 4/3/2017 at 10:39 AM, grafdog1138 said:

So far so good. I fly off with one pod in the carriers belly, and an action group to detach the pod, deploy its chute, and turn off its hibernation all at once. I let it go at about 3,000m, everything looks peachy. I can't switch to the probe, since I'm flying in atmosphere, so I watch its altitude and speed from map view. It holds at about 175m/s all the way into the ground.

That approached worked for me just now.  
175m/s is the rotational speed of Kerbin, so the probe under its parachute is moving much slower relative to the atmosphere (The speed relative to the center of Kerbin is arguably the right thing to show in map view.) The inconvenience is that I need to stay within 22.5km of the probe until it reaches the ground, which takes a long time.

If I go further than 22.5km from the probe, KSP switches to simplified physics (dropping simulation of things like parachutes) and lets the probe follow its orbital trajectory, which is a free-fall into the ground.  You can find that number 22.5km in your install directory in Physics.cfg under VesselRanges::flying::unload (probably the value that PhysicsRangeExtender lengthens, among others).  KSP is nicely configurable.  Notice that 'flying' has a longer 'unload' distance than all the others, presumably to allow recovering boosters on parachutes in the style you tried for probes.  Once the probe is on the ground it is 'landed' and physics freezes until you switch to the vessel to see it settle on the ground.

(The stock ship 'Stratolauncher', however, does not work so well.  http://forum.kerbalspaceprogram.com/index.php?/topic/137917-how-to-recover-a-stratolauncher/  The in-game examples and training in KSP are a relative weakness.)

Edited by OHara
and you can also right-click 'aim camera' on the probe to watch its chutes open, while still controlling the carrier. Also, [ ] keys switch between *close* craft even in the atmosphere.

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Why not try using FMRS to do this, sounds like exactly what it was made for

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This 

On 4/4/2017 at 4:07 PM, OHara said:

That approached worked for me just now.  
175m/s is the rotational speed of Kerbin, so the probe under its parachute is moving much slower relative to the atmosphere (The speed relative to the center of Kerbin is arguably the right thing to show in map view.) The inconvenience is that I need to stay within 22.5km of the probe until it reaches the ground, which takes a long time.

If I go further than 22.5km from the probe, KSP switches to simplified physics (dropping simulation of things like parachutes) and lets the probe follow its orbital trajectory, which is a free-fall into the ground.  You can find that number 22.5km in your install directory in Physics.cfg under VesselRanges::flying::unload (probably the value that PhysicsRangeExtender lengthens, among others).  KSP is nicely configurable.  Notice that 'flying' has a longer 'unload' distance than all the others, presumably to allow recovering boosters on parachutes in the style you tried for probes.  Once the probe is on the ground it is 'landed' and physics freezes until you switch to the vessel to see it settle on the ground.

(The stock ship 'Stratolauncher', however, does not work so well.  http://forum.kerbalspaceprogram.com/index.php?/topic/137917-how-to-recover-a-stratolauncher/  The in-game examples and training in KSP are a relative weakness.)

This brings up serious philosophical questions, such as "how fast can I slam one of these pods into the ground and still expect a working probe?". :D I'm not about to spend forever flying in a circle waiting for the pod to touch down. It kind of defeats the whole purpose of this rig: fast science milling on Kerbin. The solution? I'm thinking it might be manually timed parachutes.

Thinking out loud, here's what comes to mind: Once I find the biome I'm looking for, I slow down and take a flyby overtop of it with the cargo bay opened. In this way, I can use the Kerbnet access of the probe core to find and mark a certain point for the drop off. Now, odds are I can't really expect to hit the exact coordinates, but if the area chosen is reasonably flat I can presume that the altitude of the waypoint set is gonna be close, give or take 100m, to wherever the probe ends up. Then all I have to do is set my chutes to open with the smallest margin of space from the ground I dare (say, 500m), turnabout, fly back over the waypoint, and drop. I'll admit it to be overcomplicated, but it's bound to be more fun than circling for a half hour.

I think I'm gonna try it out.

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46 minutes ago, grafdog1138 said:

...such as "how fast can I slam one of these pods into the ground and still expect a working probe?"...

This question is realy easy to answer.

Every part has a maximal impact tolerance in the Description.

And as some Wise Heads mentioned before Drop Low and you don't have to Stay to long on the Point.

Funny Kabooms 

Urses 

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20 minutes ago, grafdog1138 said:

This 

This brings up serious philosophical questions, such as "how fast can I slam one of these pods into the ground and still expect a working probe?". :D

As said by @Urses depends on the part but its 12m/s for the okto probecore, which I assume you are using . What need to be tested (or calculated) its the actual speed and terian altitude for safe deployment.

 

 

22 minutes ago, grafdog1138 said:

 

Thinking out loud, here's what comes to mind: Once I find the biome I'm looking for, I slow down and take a flyby overtop of it with the cargo bay opened. In this way, I can use the Kerbnet access of the probe core to find and mark a certain point for the drop off. Now, odds are I can't really expect to hit the exact coordinates, but if the area chosen is reasonably flat I can presume that the altitude of the waypoint set is gonna be close, give or take 100m, to wherever the probe ends up. Then all I have to do is set my chutes to open with the smallest margin of space from the ground I dare (say, 500m), turnabout, fly back over the waypoint, and drop. I'll admit it to be overcomplicated, but it's bound to be more fun than circling for a half hour.

 

 

Ok, lets make a lot of assumption, rough rounding and a tiny bit of math...for better results actual testing is advised.

Assumptions:

1.You are cruising at 300m/s level flight, 200m above ground;

2. the pod takes 4s to slow down to 250m/s, at this point the parachute opens(deploy when safe).

3.Consider that the drag (which is the cause of the deceleration) is mostly horizontal and constant.

4.Pod decent at constant 4m/s vertical after parachute is open(instantly)

equation%20chart.gif

 

So after 4s, pod's horizontal velocity is about 40m/s, 80m lower and 700m ahead of the dropping point; the carrier is 1300m ahead of the dropping point. BUT it will take 30s more to the pod touchdown and in this time the carrier will travel 9000m, almost 10km away from the pod.

The good thing its that we noticed that we can open the parachute when the carrier is just 700m away, the bad thing its that we need to reduce the time between parachute opening and touchdown. To do this we need to either drop the pod lower or reduce the carrier speed (pick your poison).

At this point I’m going kerbal in my mind. I'm expecting some fun when I get to the game... if the anxiety don’t kill me before.

 

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