Long range ships with probes

[StainlessSteelRat]

Well, I finally managed to assemble a manned space station and was ready to depart for another planet for the very first time! Yes!! But... It sucked... I was trying to push my whole station with one nuclear engine. Yeah.. 50+ minute burn... um, no.... So... Post some pictures of your long range space craft. I have also seen people mention that they have small probes they can drop from their ships... How? I tried this, but as soon as I released the probe it became "debris".

[Brotoro]

Your probes need to have probe cores to control them (and power to keep the probe core alive, of course).

I stick OKTO2 probe bodies on anything that I may want to control as a separate piece.

[StainlessSteelRat]

They did, i coupled them to a strut with docking ports and launched them with my main space station core. As soon as i uncoupled them... debris... couldn't fly them.

[Highlad]

It sounds like its a power issue, are you sure you have some form of power generator on the probe?

[TerLoki]

I always stick a few of those fixed solar panels to the side of any spacecraft (can't remember the name), the ones that don't have to be unfolded. As long as you've got line of sight to the sun you'll have at least enough power to keep the ship active.

[TwoHedWlf]

They did, i coupled them to a strut with docking ports and launched them with my main space station core. As soon as i uncoupled them... debris... couldn't fly them.

You've done something wrong. Even if it didn't have any power it should be titled "probe" rather than debris. "Debris" is only uncontrollable objects.

[Brotoro]

Post images and/or craft files so we can see what you are doing.

[StainlessSteelRat]

Ok, here's the probe, and then a picture of what look like on the station core.

[SkyHook]

My finest Mission to Duna, although the mission was a failure.

My most ambitious mission to Jool in 0.19. This mission was wiped out by a terrible bug that eliminated all of the craft in my solar system.

[Brotoro]

Your probes look fine. So when you separate them from the mothership, you can't switch to them using the bracket keys, and they show up in the Tracking Station as debris instead of ships?

[StainlessSteelRat]

Your probes look fine. So when you separate them from the mothership, you can't switch to them using the bracket keys, and they show up in the Tracking Station as debris instead of ships?

That's correct, when I uncouple them they show as debris.

[StainlessSteelRat]

Ok, i tried again and the probe worked that time. Maybe the battery was dead? I tried on the sun side this time... Still doesn't solve the problem of how crappy my ship is, lol.

[Felsmak]

My most ambitious mission to Jool in 0.19. This mission was wiped out by a terrible bug that eliminated all of the craft in my solar system.

-snip-

Wow! That sure is a fine looking ship.

[geb]

It looks like if you had the probe pointing engine towards the sun, the fuel tank could block out all light on the solar panels. That shouldn't make the game label them as debris though.

[SkyHook]

Wow! That sure is a fine looking ship.

Well thanks! I figured that the kerbals needed a lot of room

[SRV Ron]

The bracket key should select them until they get more then 2.5K away. Then, you have to find them in map mode or from the Control Center.

[Brofessional]

This one had way more fuel than I needed, but I used it to swing around Laythe/Vall/Tylo, and sent the probes to Bop and Pol then back to the lab. Then I left the lab and extra fuel in Jool orbit and returned the crew and most valuable data to Kerbin with the return vehicle on the front.

[Caelib]

Personally, I think it's far simpler to assemble a station at its destination, but that does require more overall time and effort.

[Geschosskopf]

Well, I finally managed to assemble a manned space station and was ready to depart for another planet for the very first time! Yes!! But... It sucked... I was trying to push my whole station with one nuclear engine. Yeah.. 50+ minute burn... um, no.... So... Post some pictures of your long range space craft. I have also seen people mention that they have small probes they can drop from their ships... How? I tried this, but as soon as I released the probe it became "debris".

@ "Slippery Jim" DiGriz: Love the name, wonder how many folks recognize it?

Anyway, burn times are a function of thrust to mass. To reduce burn times, increase thrust and/or reduce mass. Increasing thrust usually increases mass both in the weight of engines and in the extra fuel they need to maintain the desired amount of delta-V. Therefore, reducing mass is usually the best bet. Carrying this to its logical conclusion, the easiest way to reduce burn times is to put all your various mission payloads on different ships. Instead of docking them in LKO and sending out 1 huge monster ship, send its pieces separately and assemble them at the destination. Because each ship is smaller, it requires less fuel for the same amount of delta-V, and fewer engines to get the desired burn time.

In this regard, consider the probes. There really aren't many good reasons for attaching them to the mothership. First, this makes the mothership heavier. Second, it makes the probes less efficient because they're usually going to different places than the mothership. The closer to its destination the mothership carries them, the more the probes have to burn to get to their own destinations, which makes them bigger and in turn makes the mothership even heavier. And third, the closer to its own destination the mothership releases the probes, the closer together in time they and the mothership arrive, which makes for a more difficult control situation. You can avoid all these problems by sending the probes out as separate ships from the get-go.

That said, I have on occasion made "probe bombs" of multiple probes attached to a single mothership. But in these cases, the probes were all going to the same planet and the "mothership" was just a big probe itself, nothing more than a fuel tank and engine. All the other stuff on the mission was in other ships.

[problemecium]

The Kerbatar. So named because my heroic efforts to make it not look like a space ***** ended up making it look like the Avatar from EVE Online.

[Dangerous_Beans]

In this regard, consider the probes. There really aren't many good reasons for attaching them to the mothership. First, this makes the mothership heavier. Second, it makes the probes less efficient because they're usually going to different places than the mothership. The closer to its destination the mothership carries them, the more the probes have to burn to get to their own destinations, which makes them bigger and in turn makes the mothership even heavier. And third, the closer to its own destination the mothership releases the probes, the closer together in time they and the mothership arrive, which makes for a more difficult control situation. You can avoid all these problems by sending the probes out as separate ships from the get-go.

+1

i'll also add that probe bombs result in very complex ships that can be a pain to launch. i remember building a 5 part probe bomb to fire a Jool, and every time i would try to launch it, it would break. i pulled it apart and launched them as 5 separate probes, and had no issues getting the damn things into space.

so as a general guide; launch multiple simpler ships, rather than one large ship.

[Jouni]

Anyway, burn times are a function of thrust to mass. To reduce burn times, increase thrust and/or reduce mass. Increasing thrust usually increases mass both in the weight of engines and in the extra fuel they need to maintain the desired amount of delta-V. Therefore, reducing mass is usually the best bet. Carrying this to its logical conclusion, the easiest way to reduce burn times is to put all your various mission payloads on different ships. Instead of docking them in LKO and sending out 1 huge monster ship, send its pieces separately and assemble them at the destination. Because each ship is smaller, it requires less fuel for the same amount of delta-V, and fewer engines to get the desired burn time.

If a ship requires 3 minutes to complete a burn, you can dock two of them together, and it still only takes 3 minutes to complete the burn. Hence, as a first-order approximation, you should send the payload in as few ships as possible.

Of course, larger ships are harder to handle and cause more lag, and they also don't work that well with physics warp, so you don't save that much by combining the payloads in a single ship. On the other hand, you usually spend more time planning the maneuvers and waiting for the ship to reach a maneuver node than actually executing the maneuvers, so sending fewer ships can also save more player time than the reduction in burn times would suggest. Based on this, I would suggest building relatively large ships that are still small enough to behave well.

[SkyHook]

Well the rules that I follow are these: Don't make it larger than it has to be, and don't make more trips than you have to make. Since it's your first time, you should go with a medium-sized or smaller ship. Entire space stations will get you in trouble. Try this: A mothership and a lander that you can use for planetary operations. If you choose duna, then you can land with practically no fuel, and dock with your ship after ascent. After return to Kerbin, you can simply aerobrake and return to the surface. Try that!

[TerLoki]

Well I only discovered the uses of the F keys recently (I am ashamed), right at the end of my first big multi-launch manned interplanetary mission to Duna, Dres 1, and the first mission like that in general. Unfortunately that means that I missed most of it and never got a picture of the ship intact (I'll have to rebuild it at some point for pics), but I DID get some shots of the spectacular monument to poor planning and seat-of-the-pants flying. All because I didn't feel like making a four-man crew return vehicle. So how do you get two three man capsules out of orbit from low altitude at once?

I see nothing that can go wrong with this.

And funnily enough...

Nothing did! Well, aside from the Duna Heavy capsule that was the originally planned reentry vehicle spilling its RCS tanks everywhere. Cleanup on aisle 7!

Next up, the Dyson, my Eve flyby and first big ship to use electric propulsion. It... Hasn't gone to plan. The length of burns required meant I had to do two passes around Kerbin to get up enough velocity to get to Eve, and the ensuing awkward encounter position meant that I just had enough dV to park in orbit and wait for rescue rather than return to Kerbin.

Here's the full ship getting a gravity assist at the Mun to help change inclination. In retrospect, this little unplanned encounter may have been the source of a good chunk of my trouble. The ship consists of four modules which, front to back, are the fuel module, power/propulsion module, habitat/lab module, and Dres CTV used for ferrying the crew and as an escape craft.

And here's the Dyson after ditching the now-empty fuel module, as it moves into a stable orbit around Eve to wait for rescue. In the form of...

This guy, the Dyson N. Which Jeb has decided to hitch a ride on, for some reason. Well, actually there is a reason, I decided to send a Gilly lander along with this glorified fuel tanker, and then forgot to send it to the pad unmanned. Then something went wonky as it was orbiting the sun and it was mysteriously recaptured by Kerbin despite no encounters appearing in its path, so back to the last launch for me. Think I'll add another NERVA or two and some fuel tanks just in case. The way these maneuver nodes have been treating me I figure better safe than sorry.

Edited February 24, 2014 by TerLoki

[Geschosskopf]

If a ship requires 3 minutes to complete a burn, you can dock two of them together, and it still only takes 3 minutes to complete the burn. Hence, as a first-order approximation, you should send the payload in as few ships as possible.

Except that there's a practical limit to the number of engines you can have unless you're willing to go Whackjob. Thus, beyond a certain point, it becomes impossible to add stuff to the ship without increasing the burn time. And at no point in the additive process do you decrease it, which is what the OP wanted to do. A 3-minute burn time needs no further work but the 50-minute time the OP mentioned requires drastic change.

In general, decreasing payload mass is the only way to make a significant reduction in burn time. If the mission requires a given amount of payload, then any payload removed from 1 ship has to go into another ship.