What did you do in KSP1 today?

[Pthigrivi]

9 hours ago, Daveroski said:

Direct from launch pad / runway to the station. Once you have figured out the timing from the map view it is loads of fun and cheaper. No transfer required.

No problem from Kerbin, but if you're using reusable landers/tankers/busses it helps to have a return-to-stuation lane, especially with LS when time is of the essence.  

Edited April 23, 2018 by Pthigrivi

[jack gamer]

I launched an OPT plane and began orbiting minmus.

Unfortunately it was a landing failure

[jack gamer]

Now im stranded

[Ace in Space]

Oh man, today was eventful. All them irons in the fire and whatnot.

The first thing that happened was that I realized I'd forgotten to launch one last craft for Tiger's Eye Station - an orbital scanner to show me where the best mining spots are. Since the other crafts had just left and weren't even at the Mun yet, I just hastily launched a scanner that was equally-hastily constructed. I just took an Ugly Space Flower, ripped the comm dish off and replaced it with a scanner, then glued a collapsible non-relay antenna to the side. Seems to be working out just fine.

Spoiler

The trip to Eve orbit was fairly uneventful. I plotted the intercept and plane change maneuvers before the crafts got past the Mun, which turned out to be important. The Mining Lander is flown by an engineer (Eridin Kerman), not a pilot - it has a probe core on it for SAS functionality, but it's not designed to operate remotely or very far from the Station. So it has no antenna except what's built into the lander can. Which means that once it got out of range, I lost the ability to plot maneuvers. With the ones I'd set up before leaving Kerbin's SOI, I was able to still get into roughly the right place, but ultimately wasn't as spot-on as I'd hoped, and overshot the planet slightly - not enough to leave its SOI, but enough to end up orbiting backwards, and fairly low. "Wrong Way Eridin" will never live it down.

As always, the multitasking and sloppy burns have resulted in a mess.

Spoiler

I started to clean it up somewhat, but wasn't able to do much beyond adjusting a couple comm sats, because time was up for Ruby 4.1, coming home from Duna. Re-entry was uneventful, but I got a particularly nice view on the way in.

Spoiler

You can even see the Mun silhouetted in the Sun's glare!

Immediately after this (as in, within a day or two), burns began on the Dres project. The moment of truth for my delta-v budgeting efforts. You may recall that my numbers were not looking good for three of my crafts.

	Drill	Converter	Com 5
Delta-V Left (as of last report)	1851+	1834	~2072
Delta-V Requirement for Capture	1897	1956	2207

The drill was potentially up to 46m/s short of the mark, but with an unknown amount of bonus delta-v from the ascent stage, while my numbers predicted that the converter would be 124m/s short. The fifth com sat was also expected to run about 200m/s short, but I waved this off as an acceptable loss. The first craft in was the drill, but just before it reached Dres's SOI, I started to have doubts about whether it could make it, and was struck with an idea. I transferred the fuel from two of its four tanks into the others, then manually decoupled them to reduce the craft's mass.

It worked, and the drill successfully captured into orbit with a little fuel left to spare. After that, I pulled one craft after another into orbit, just as planned, though many of them are running dangerously low on fuel and I may not be able to get the comm sats into a nice, pretty configuration. But that can be solved by sending a claw-equipped refueler at the next launch window, when I'll be sending the first actual expedition to land on Dres. Comm Sat 5, as expected, didn't make it, and had to be terminated, but there's no great loss there, and in fact that's why I sent five - so I could afford to lose one. The fuel tank cut it surprisingly close - I knew I had less delta-v in it than calculated due to having used some of it during ascent, but I didn't realize just how much I'd used. But it, too, made it into orbit, albeit at a very strange angle.

The real tension revolved around the converter unit. It's absolutely critical to the operation here, and there was no wiggle room to be had from leftover fuel or dropping excess mass. The numbers said it would run 124 m/s short, and its only hope would be to burn the rest of the way with RCS. My numbers turned out to be slightly off, but were still close enough to be oddly satisfying.

Spoiler

But it was also worrying, because it meant that I would indeed need to fall back on monoprop, and I wasn't sure if I'd be able to pull it off. The RCS burn is slow, and not very powerful. I wasn't sure if I had enough fuel, or would be able to achieve the burn fast enough.

 

All I could do was drop the engine, engage the RCS, and hold H. It may not have been the longest burn in seconds, but it felt like a tense eternity, until...

 

So now Ruby has returned to Kerbin, and both the Gilly and Dres wagon trains have arrived at their destinations and are awaiting cleanup.

Spoiler

Irons out of the fire and ready to be worked at a leisurely pace.

[Daveroski]

10 hours ago, MR L A said:

What? Are you suggesting that the higher velocity at LKO makes reaching the Mun cheaper that starting at, say, an altitude of 150k? That seems to be the only way to understand your sentence and it is fundamentally wrong. it takes less dV to reach the Mun from 150K than it does from 80K. 

I have had my pills so I don't need to argue.
If you say that launching from Kerbin and getting into a 150K orbit and then going on to the Mun is cheaper than Launching from Kerbin and getting into an 80K orbit and then going to the Mun... well, look at me.. I'm smiling and nodding.

[Daveroski]

1 hour ago, Pthigrivi said:

No problem from Kerbin, but if you're using reusable landers/tankers/busses it helps to have a return-to-stuation lane, especially with LS when time is of the essence.  

It is fun that people arrive at different conclusions given similar circumstances. I always found that when I was using Life Support it was preferable to get to the station in as short a time as is reasonably safe to do so. Taking crew up for transfers meant that I could use a Space Plane from the runway with no extra life support and dock with my station, drop off the crew and then land back at the runway. My Kerbin/Mun shuttle also had minimum life support as it was only going from station to station. My Mun / Mimnus shuttle had to have 25 days of life support (Including safety Margin) for 10 people. I found that while Kerbin>Mimnus was fine, it was more efficient to go Kerbin<>Mimnus via the Mun. My LKO Station and my Mun station both see quite a lot of traffic. So.. different strokes eh?

 

[JadeOfMaar]

I expanded my Loki base today, and realized, in preparation to launch the refueler for the station that the moon has at best 1% Water anywhere, and I need it to produce FusionPellets and have a large supply of Water to burn with the FusionPellets.  Plenty creativity has been found and shall be used for alternate solutions for the ultimate Gael return problem. The situation makes things fun and challenging, but some certain mod features being broken takes a bit away from the fun.

The base is in the Petrification biome, with zero Water.  The base is trickling it out via a Mono + Oxidizer fuel cell in the Doc Science Lab so I need > 1 of this lab.

Spoiler

The Gael return problem is such that the orbital station is possibly greatly under-fueled for a speedy return transfer. The crew made the expected 6 year transit to get here in just 1 year... but their faith in KER is low and they don't wish to risk getting stuck on a hyperbolic trajectory to anywhere in the universe where 22km/s sounds like plenty but ends up being less than half of what they really need. It's a pleasant surprise gameplay-wise. It makes Catullus and Tarsiss (the other moons) much more inviting for a re-visit or more, and opens quite the window of opportunity to experiment with LH2 and the likes of Methane.

I almost wish I still had a life support mod in this game install. Then I would have better anticipated the Water shortage. 

 

Edited April 23, 2018 by JadeOfMaar

[MR L A]

9 hours ago, CatastrophicFailure said:

They’re probably hiding from you, curled up in the corner muttering something about “finding a happy place.”

Don’t forget the extra delta-V you need to get to 150k in the first place. 

His original comment didn't make any mention of getting to the launch altitude - that it was why it was wrong. He simply stated 80k to mun is "easier because you are going faster" than a higher orbit.

8 hours ago, qzgy said:

Something something oberth effect. Also, have to concur with @CatastrophicFailure - You're burning fuel on the way up to 150k that could be used to push the apoapsis farther from 80k.

IMO would start at a lower altitude.

See above. Also original altitude given by me was just an example - by his logic it is easier to get to the mun from 80k than 800k.

5 hours ago, Daveroski said:

I have had my pills so I don't need to argue.
If you say that launching from Kerbin and getting into a 150K orbit and then going on to the Mun is cheaper than Launching from Kerbin and getting into an 80K orbit and then going to the Mun... well, look at me.. I'm smiling and nodding.

That isn't what I said and nor is it what the original comment was saying.

[Tyko]

18 hours ago, Pthigrivi said:

18 hours ago, Daveroski said:

80K

It makes launching to rendezvous really cheap. Makes it easy to de-orbit junkers. It also means you are going faster which makes leaving orbit to go to the Mun a little less expensive too.

 

All good reasons. I often build mine a little higher (90-100) because it leaves more room underneath for a catch-up rendezvous lane. 

I usually build anything long-duration much higher.

IRL the ISS orbits 4X higher than the Karman line - ISS is at 400km, Karman line is 100km. So I build big stations around 250 - 300km to somewhat emulate the actual challenges of reaching and maintaining a station despite the fact that Kerbin's atmosphere goes to 0 density at 70km

Edited April 23, 2018 by Tyko

[Daveroski]

16 minutes ago, Tyko said:

I usually build anything long-duration much higher.

IRL the ISS orbits 4X higher than the Karman line - ISS is at 400km, Karman line is 100km. So I build big stations around 250 - 300km to somewhat emulate the actual challenges of reaching and maintaining a station despite the fact that Kerbin's atmosphere goes to 0 density at 70km

I used to do much the same. 400K was my cellar for a while.
I had some prettification mods installed and just switched to LKO. The views were, I think, the tipping point. Watching the sun rise through the curvature of the atmosphere was quite pleasing. The scenery made it less of a job and more of a holiday.
The only reason I never went down to 75K was that I have kerbals working at the station, upgrading vessels and building in orbit. The act of climbing up and down ladders can sometimes cause changes to the velocity of the station thereby changing the your Pe. Even at 80K I still have to check Ap and Pe after every EVA just to make sure that I haven't done something too horrific to contemplate.

[Tyko]

On 4/23/2018 at 7:46 AM, Daveroski said:

I used to do much the same. 400K was my cellar for a while.
I had some prettification mods installed and just switched to LKO. The views were, I think, the tipping point. Watching the sun rise through the curvature of the atmosphere was quite pleasing. The scenery made it less of a job and more of a holiday.
The only reason I never went down to 75K was that I have kerbals working at the station, upgrading vessels and building in orbit. The act of climbing up and down ladders can sometimes cause changes to the velocity of the station thereby changing the your Pe. Even at 80K I still have to check Ap and Pe after every EVA just to make sure that I haven't done something too horrific to contemplate.

haha "Jeb, dude, you bumped the station out of orbit again...try to be more careful next time..."

Edited April 30, 2018 by Tyko

[Pthigrivi]

8 hours ago, Daveroski said:

It is fun that people arrive at different conclusions given similar circumstances. I always found that when I was using Life Support it was preferable to get to the station in as short a time as is reasonably safe to do so. Taking crew up for transfers meant that I could use a Space Plane from the runway with no extra life support and dock with my station, drop off the crew and then land back at the runway. My Kerbin/Mun shuttle also had minimum life support as it was only going from station to station. My Mun / Mimnus shuttle had to have 25 days of life support (Including safety Margin) for 10 people. I found that while Kerbin>Mimnus was fine, it was more efficient to go Kerbin<>Mimnus via the Mun. My LKO Station and my Mun station both see quite a lot of traffic. So.. different strokes eh?

 

Yeah its an interesting problem. It seems sensible that if you're using lower ISP lifters to get out of the atmosphere you'd want to stick right at 80k as a delivery point (not to mention if you're mining it fuel is basically free above this point.) Most of my inbound vessels aerobrake their AP down to a point that times out to hit the station on the second pass, so its really not very often I even need the low altitude rendezvous lane. Its really only if Im doing something funny like topping off an interplanetary vessel with a tanker in LKO and then scooting over to the primary station to wait for a shift change. The dV difference between 80k and 90k is so slight it seems worth it as a safety/convenience feature.

Edited April 23, 2018 by Pthigrivi

[Daveroski]

8 minutes ago, Pthigrivi said:

Yeah its an interesting problem. It seems sensible that if you're using lower ISP lifters to get out of the atmosphere you'd want to stick right at 80k as a delivery point. Most of my inbound vessels aerobrake their AP down to a point that times out to hit the station on the second pass, so its really not very often I even need the low altitude rendezvous lane. Its really only if Im doing something funny like topping off an interplanetary vessel with a tanker in LKO and then scooting over to the primary station to wait for a shift change. The dV difference between 80k and 90k is so slight it seems worth it as a safety/convenience feature.

I park my Interplanetary Ships at 250KM until they are ready to leave then I lower the Pe to 70K and wave at the folks back home as I leave.

[SwissSpace93]

I have a question about docking with Space Stations, is there a formula that calculate the angle between the Station and the rocket?

Many Videos in Youtube the rocket fly directly to the station from the KSC, how to get the needed Phase Angle for this?

[Daveroski]

7 minutes ago, SwissSpace93 said:

I have a question about docking with Space Stations, is there a formula that calculate the angle between the Station and the rocket?

Many Videos in Youtube the rocket fly directly to the station from the KSC, how to get the needed Phase Angle for this?

I do it by eye in the map view.

Confidence varies with experience with the vessel making the trip.

 

[CatastrophicFailure]

3 hours ago, MR L A said:

His original comment didn't make any mention of getting to the launch altitude - that it was why it was wrong. He simply stated 80k to mun is "easier because you are going faster" than a higher orbit.

Going faster is exactly what makes it easier, bruh.  As first described by a dude just about everyone here knows called Oberth. “The use of an engine at higher speeds generates greater mechanical energy than use at lower speeds.”

[Daveroski]

5 minutes ago, CatastrophicFailure said:

Going faster is exactly what makes it easier, bruh.  As first described by a dude just about everyone here knows called Oberth. “The use of an engine at higher speeds generates greater mechanical energy than use at lower speeds.”

When I'm playing I call it 'Pulling a Hermie'  But when I am trying to explain anything in the forums, I find it better to try to avoid technical terms.

[Hotel26]

56 minutes ago, SwissSpace93 said:

is there a formula that calculate the angle between the Station and the rocket?

This is an excellent question.

1.  I think a lot of Kerbonauts simply launch from KSC when the target reaches the tip of the Kerbaran desert to the west of KSC and across the water.

2. At one time, I measured how long my launch took to get to a 100km apoapsis and at what longitude downrange that was.  Let's say 5m40s.   If the station was in a 100x100km orbit, then it would be traveling at a precise speed.  I then calculated how far uprange (longitude) the station would be such that its orbital speed took it, in 5m 40s, to the downrange launch apoapsis longitude.  Thus, when the target reaches the uprange longitude, I launched the rocket then.  The results could be rather spectacular, such as a 3-5 km separation at the apoapsis burn, usually an error due only to inclination.

But 1 is a lot easier than 2 and it's good enough because....

3. if you launch at the right time (when the target is at the right place), then if, during the coast, the intercept looks good, you can simply burn according to the navball to make the rendez-vous, which compensates for timing/inclination errors.

Do get some experience trying this and that will make more sense than any attempt by me at a further explanation.

---

On my own front today, I had a Pterodactyl running a new Krew Bus 2,300 kms out to Baikerbanur from KSC -- only the pilot elected to land 30 kms short due to fuel shortage just before a ridge he didn't think he could get over.

So I built a new emergency fuel tanker, provisionally dubbed Worm that fits inside an Ursa transport.  (Click on the first for a full-size slideshow.)

 

 

I also got to fly the amazing KerbalX.Bloojay.V-Wasp Mk1...

Wow.  I'm gonna fit one of these on the back of a Pterodactyl and go tackle that tallest mountain on Kerbin.  [1.4 and personal chutes will not reach my desktop for another year]

 

Edited April 23, 2018 by Hotel26

[MR L A]

 

2 minutes ago, CatastrophicFailure said:

Going faster is exactly what makes it easier, bruh.  As first described by a dude just about everyone here knows called Oberth. “The use of an engine at higher speeds generates greater mechanical energy than use at lower speeds.”

That is true, but I believe you are misapplying it to the situation being addressed. If I am in HKO, somewhere around 10 000 000m, I will have a substantially lower orbital velocity, or in OP's language I'll be going *slower* - not "faster", than if I was in the 80 000m orbit he suggested, which is doing somewhere around 2200m/s I guess.

However, in terms of how much "easier" it is for either one of us to reach the target at 12 000 000m, something that we can only measure in dV, it is pretty clear that I, from my 10 000 000m orbit, have an easier task than OP at his/her orbit.

This is because, whilst the Oberth's comment is obviously true, "going faster" or higher orbital velocity is not how we measure the ease of a task - difference in velocity is. My difference in velocity to the target is much lower at HKO than it would be at LKO and hence I have the easier task despite going slower.

What Oberth is addressing is, of course, the benefit of burning prograde at PE for efficiency and vice versa - or analogously, lengthening the mechanical lever in order to increase "mechanical energy"/decrease mechanical effort. I believe, by extension of analogy, what I am talking about is moving the position of the fulcrum closer to the object being moved (vessel closer to target), also decreasing mechanical effort required, but by a larger amount in this example.

I think we probably have some confusion about what "faster" actually means too, especially when thinking about what our frame of reference is. For example, accelerating (burning prograde) should increase orbital velocity correct? Yet accelerating prograde twice, at pe then ap, results in a lower orbital velocity (going slower by OPs logic) despite being in a more energetic orbit with a lower difference in velocity between myself and higher circular orbits.

[Triop]

17 days ? ? ?

Meanwhile getting some science from Baikerbanur (old base)

Still need to climb my mountain...

It scares me, I need to grow some

[Cavscout74]

9 minutes ago, Triop said:

Still need to climb my mountain...

I was out of touch for a few days, that's still going?!?!     You have SOOOOO much more patience than I do

Edited April 23, 2018 by Cavscout74

[Triop]

42 minutes ago, Cavscout74 said:

I was out of touch for a few days, that's still going?!?!     You have SOOOOO much more patience than I do

I'm obsessed with this contract mountain, also there is not much more to do at the moment accept for flying rubberducks from Hong Kong tourists into space.

My kid is here on holiday so I can't play much KSP

 

Edited April 23, 2018 by Triop

[juanml82]

4 hours ago, MR L A said:

 

That is true, but I believe you are misapplying it to the situation being addressed. If I am in HKO, somewhere around 10 000 000m, I will have a substantially lower orbital velocity, or in OP's language I'll be going *slower* - not "faster", than if I was in the 80 000m orbit he suggested, which is doing somewhere around 2200m/s I guess.

However, in terms of how much "easier" it is for either one of us to reach the target at 12 000 000m, something that we can only measure in dV, it is pretty clear that I, from my 10 000 000m orbit, have an easier task than OP at his/her orbit.

This is because, whilst the Oberth's comment is obviously true, "going faster" or higher orbital velocity is not how we measure the ease of a task - difference in velocity is. My difference in velocity to the target is much lower at HKO than it would be at LKO and hence I have the easier task despite going slower.

What Oberth is addressing is, of course, the benefit of burning prograde at PE for efficiency and vice versa - or analogously, lengthening the mechanical lever in order to increase "mechanical energy"/decrease mechanical effort. I believe, by extension of analogy, what I am talking about is moving the position of the fulcrum closer to the object being moved (vessel closer to target), also decreasing mechanical effort required, but by a larger amount in this example.

I think we probably have some confusion about what "faster" actually means too, especially when thinking about what our frame of reference is. For example, accelerating (burning prograde) should increase orbital velocity correct? Yet accelerating prograde twice, at pe then ap, results in a lower orbital velocity (going slower by OPs logic) despite being in a more energetic orbit with a lower difference in velocity between myself and higher circular orbits.

If this is about the argument of whether to burn from LKO or from a high orbit at about the same distance from Kerbin than Minmus, there is a better alternative.

Go to Minmus (however, this is easier done if going to the Mun).

Refuel there.

Now plot a burn into Kerbin so your Pe is during the interplanetary transfer window you seek and at the correct side of Kerbin to burn to go wherever you want to go. That should take you about 300 m/s iirc.

Now you are in a highly eliptical Kerbin orbit: your Pe takes full advantage of the Oberth effect and your Ap is near the edge of Kerbin' SOI (or not, if you started at the Mun, but it's still about 100 m/s away). More importantly, your tanks are nearly full.

Burn at your Pe, or near it

Profit!

[papuchalk]

Started the Duna Rover mission today. I am surprised, it is one of the best missions i have ever had in KSP so far. Visually, and gameplay too.

story here

https://imgur.com/a/Nqg5ACR

Edited April 23, 2018 by papuchalk

[Triop]

"Tell Jeb we found his frisbee, over."

"Tell Jeb we can't take it home, not enough storage space, over and out."

Edited April 23, 2018 by Triop