Stack separators and very small probes

[Skorpychan]

Having reached Duna, I want to put satellites into orbit around it and Ike. So, I figured, why not do them all at once?

However, I'm unsure of how stack separators work. Mainly, will they propel the probes off into other orbits, or crash into the probes later just after release?

Here's the section of the ship in question:

I used the tiny-sized stack separators, that come off into a part separate from each side, as I hear they don't impart any force. The probes only have ion engines, and are basically an engine, fuel tank, batteries, probe body, RTG, and solar panels, with an antenna on top.

Also, will this assembly stay alright on launch?

(Also, ignore my spelling; I know I spelled satellite wrong in the ship name.)

Edited August 2, 2013 by Skorpychan

[Scorpi15]

Stack separators still have a bit of force, just less. They also leave debris is orbit. The probes will have to make inclination changes and such, but unless your trajectory is suborbital nothing will crash.

[dlmarti]

1. place the sats approximately where you need them, one at a time, you don't need to blow them off all at once.

2. You do not need solar panels AND batteries AND generators. Typically if you have a generator you do not need batteries at all (I said typically, no need for the obligatory posts).

3. Also consider using docking nodes, instead of seperators, they are more mission flexible.

[Kimberly]

If you want to decouple stuff with zero force applied, attach a strut to them. Once you decouple, the strut will dissolve and the payload will be released, but no force will be applied. Just be sure to carefully maneuver your ship away, so you don't hit the payload or burn it with your engines. If you start the strut on your main craft then attach it to the payload, the payload won't have any strut marks.

[Anton P. Nym]

Curious: I have a sketch in my pocket right now of a similar concept, the Arro Dockable Modular Probe Array (aka "Probekabob") but I was thinking of using the Clampotron Jr. adaptors rather than separators... thinking of keeping debris down when dispersing probes, and also of reducing the chance I might accidentally stage them all off in a spectacular fireworks display by hitting the spacebar at the wrong moment.

I'll be very interested to hear how well your design works, let us say.

-- Steve

[dlmarti]

Curious: I have a sketch in my pocket right now of a similar concept, the Arro Dockable Modular Probe Array (aka "Probekabob") but I was thinking of using the Clampotron Jr. adaptors rather than separators... thinking of keeping debris down when dispersing probes, and also of reducing the chance I might accidentally stage them all off in a spectacular fireworks display by hitting the spacebar at the wrong moment.

I'll be very interested to hear how well your design works, let us say.

-- Steve

It works fine, this is my refueler heading to Mun. When it gets there it will drop these probes into orbit.

http://steamcommunity.com/sharedfiles/filedetails/?id=165853381

[alterbaron]

If you want to be sure you won't impart any additional velocity to your probes, you could attach them with docking ports.

You can attach the probe directly to the docking port (no port required on the probe).

When the time comes, just click the docking port and choose "Decouple Node", and it will separate.

[Epthelyn]

The design looks pretty similar to something I was working on this morning and got to Jool an hour or so ago, at least as far as the probe decoupling is concerned:

Small battery + Probe body (and 2 Gigantor XL solar panels) + 2x Xenon + Ion Engine attached via (different to yours) the red and white decoupler as shown in the picture and then connected to the rocket by a cubic octo strut because I forgot about the side attachment parts (as always )

Anyway, judging by the fact that the probes on my rocket survived full power from mailsails from ground to LKO and then a 20-30 minute burn to Jool there's no problem with transit. If your crazy array of struts doesn't hold it together then I'd be surprised.

Nor should there be any problem decoupling. I wasn't aware of any force from the decoupler when I removed the probe and could easily switch craft and push away using the ion; unless you're really picky about your current orbit, that's really not going to make any difference to anything other than the gap between the probe and rocket.

If there IS a force on the probe, then there will be no problem either. The pushing force on the main rocket will push back the decoupler towards the probe but at the same time the decoupler will exert the same force on the probe; the decoupling force works on both sides of the part. You'll have the stack separator moving away from the rocket at v m/s and the probe will be moving away at ~2v m/s. Either way, the speed gained from a small stack separator isn't anything significant (probably <1m/s).

[toric5]

stack separators actually provide more force than decoplers, but if you strut them, no force is applied.

[Skorpychan]

Anyway, judging by the fact that the probes on my rocket survived full power from mailsails from ground to LKO and then a 20-30 minute burn to Jool there's no problem with transit. If your crazy array of struts doesn't hold it together then I'd be surprised.

Nor should there be any problem decoupling. I wasn't aware of any force from the decoupler when I removed the probe and could easily switch craft and push away using the ion; unless you're really picky about your current orbit, that's really not going to make any difference to anything other than the gap between the probe and rocket.

If there IS a force on the probe, then there will be no problem either. The pushing force on the main rocket will push back the decoupler towards the probe but at the same time the decoupler will exert the same force on the probe; the decoupling force works on both sides of the part. You'll have the stack separator moving away from the rocket at v m/s and the probe will be moving away at ~2v m/s. Either way, the speed gained from a small stack separator isn't anything significant (probably <1m/s).

I like to be sure when I strut things. And there's seven mainsails and twelve aerospikes punching this thing skyward at launch, it being a holdover from when I had gravity turns wrong and was taking off retrograde.

The struts should keep everything together? Interesting. Looks like I'll have to be very careful when moving the probes away, then.

Curious: I have a sketch in my pocket right now of a similar concept, the Arro Dockable Modular Probe Array (aka "Probekabob") but I was thinking of using the Clampotron Jr. adaptors rather than separators... thinking of keeping debris down when dispersing probes, and also of reducing the chance I might accidentally stage them all off in a spectacular fireworks display by hitting the spacebar at the wrong moment.

I'll be very interested to hear how well your design works, let us say.

-- Steve

I'll fire it up today, and see how it works. With two LV-Ns instead of one, the burns shouldn't take all day like they did last time.

I'm not holding out much hope; I threw this together before bed when I was rather tired. I don't do my best thinking when drowsy.

EDIT:

Okay, threw it up there. No launch issues, no LV-N overheats. A bit of a foulup with insertion, with Ike interfering a bunch and nearly ejecting the mothership from the Duna system, but that worked out.

If you noticed that I'd missed the fuel lines out for the LV-Ns, you'd be right. Launched it, realised halfway to the mun's orbit that I'd screwed up. Had to revert.

I discovered a more efficient launch trajectory.

Probes separated just fine.

I need more power on them; the engine shuts down after only a few seconds of thrust!

Edited August 2, 2013 by Skorpychan

[Anton P. Nym]

For what it's worth, I ran a couple tests of the Probekabob last night.

There it is in orbit; 8 probes on a stick truss, with one Clampotron Jr attaching the truss to the upper stage booster and a Clampotron on the other end to dock it to another craft. Alas I couldn't mount the probes onto the truss with Clampotron Jrs without having the adaptors intermesh and thus become unable to separate. That got very, very frustrating. In the end I gave up and just mounted stack separators onto structural plates instead.

Strutting them in did kill relative motion, but I found in the end that the motion (for my purposes here, anyway) could be useful so I removed the struts.

First landing test of the final model of probe (yet unnamed) carried by the Probekabob array; cheap, stable, easy to land, and light enough to carry 8 on a stick anywhere in the solar system. Finding out that engine bells make for great one-use shock absorbers simplified things greatly.

-- Steve

edited to add: I thought of a name for the probe, the Arro "Popcorn".

Edited August 2, 2013 by Anton P. Nym
Aha! I thought of a name

[Clouds]

Here's the section of the ship in question:

Off-topic, but I love how your probes look like classical ray-guns. Zap zap!

[Skorpychan]

Ah, you're dropping them onto things?

I'll have to remember that engine trick, too. Might prove handy for lander probes.

I was just planning to use mine as an orbital satellite net around the two bodies in the system.

[krenshala]

First landing test of the final model of probe (yet unnamed) carried by the Probekabob array; cheap, stable, easy to land, and light enough to carry 8 on a stick anywhere in the solar system. Finding out that engine bells make for great one-use shock absorbers simplified things greatly.

-- Steve

edited to add: I thought of a name for the probe, the Arro "Popcorn".

I was going to suggest calling them "Shish" probes

[Anton P. Nym]

Last interruption, I promise.

For those who want it, I posted the craft file over in the Spacecraft Exchange forum.

-- Steve