Kerbin - Mun fuel station mission. Establishing K.G.01 and K.G.02

[BechMeister]

@Sylvi Fisthaug Aw thats really cool  Glad you could use some of my experimentation. The last thing i made myself was an "adapter" from the medium docking ports to the small. That the big tug drone can connect to. It will also give it more docking options, as i have more small ports than medium. I was thinking about putting them at the ends of the station.

Any way the adapter looks like this, plane and simple. Maybe you can use the same idea?



Pretty simple straight forward idea.

Edited May 22, 2023 by BechMeister
re-added lost image links

[obney kerman]

I really like the look of these designs! The slow evolution of spaceplane shapes and the utilitarian and modular tugs and station parts are all super inspiring for me, and the station looks really good! Definitely going to remember this design whenever I get around to making stations/fuel depots in KSP2. And proper space shuttle/SSTO designs, too...

[Sylvi Fisthaug]

12 hours ago, BechMeister said:

Pretty simple straight forward idea.

The best ideas are often the simplest ones! 

Currently battling bugs assembling, and Bob snuck into my escape pod on launch, even though he was advised not to... 

My (your) tug, or the large one, have one medium docking port in the rear, and one small docking port in the front. Easy enough to just reverse control of the pod in the parts manager, but it lacks a bit of "oomph" to move heavier stuff, and relies on that stuff having RCS thrusters attached to it. 

Having some rocket engines attached to the end of the tugs might imrpove quality of life on that note, and that's of course where the adapters come in. So yes, might steal that idea as well. 

[BechMeister]

On 4/26/2023 at 9:52 PM, Sylvi Fisthaug said:

Currently battling bugs assembling, and Bob snuck into my escape pod on launch, even though he was advised not to... 

My first Mun mission became a rescue mission because Jebediah snug onboard my spaceship.. It was an apolo style lander.. and there were only room for 3 in the pod. My rescue mission needed a rescue mission though. because as soon as Valentina went from the orbiter to the lander.. there were no one in the orbiter... but the 2nd rescue mission saw all 5 kerbels get home safe.. Now i just have a empty orbiter orbiting the moon.. ill pick it up later i guess x)
 

On 4/26/2023 at 9:52 PM, Sylvi Fisthaug said:

My (your) tug, or the large one, have one medium docking port in the rear, and one small docking port in the front. Easy enough to just reverse control of the pod in the parts manager, but it lacks a bit of "oomph" to move heavier stuff, and relies on that stuff having RCS thrusters attached to it. 

Having some rocket engines attached to the end of the tugs might imrpove quality of life on that note, and that's of course where the adapters come in. So yes, might steal that idea as well. 

Yeah - well I use the small tug drones with only RCS thrusters to navigate around with modules. They can handle 9t-10t easily enough.. but when i were moving the big 18t monopropellant tanks for the station.. they were struggling a lot. 

The big tug drone with the engine is really just to push the LEOs and the station around. I usually park the big ones around the station, then used the small ones to attach things to the big ones... But yeah, maybe its the center of mass? I have not yet experimented with the hydrogen engines.. I am saving them for my interplanetary vehicles. Any way... my point being. I find the small ones move things around pretty good as they dont have the mass of an engine to push around as well.

 

 

On 4/26/2023 at 8:40 PM, obney kerman said:

I really like the look of these designs! The slow evolution of spaceplane shapes and the utilitarian and modular tugs and station parts are all super inspiring for me, and the station looks really good! Definitely going to remember this design whenever I get around to making stations/fuel depots in KSP2. And proper space shuttle/SSTO designs, too...

Thanks! I would lie if i tried to deny spending an evening fiddling with aesthetics when it comes to design of the station x) The space planes got to look the way they did out of necessity.. but they look good yeah. Right now I am trying something new as for refueling vehicles now. I did not like that i could only move like 4t fuel - I try to make a reusable craft that can move 8t at the time. Its been 50% successful so far.  

I'm going to make a little update tomorrow after i've slept.

But thanks, the kind words makes the struggles barrable ^^' 

Edited April 27, 2023 by BechMeister

[BechMeister]

//////////MISSION UPDATE\\\\\\\\\\
- Revising KSC-LKO refueling vehicles - 

Test vehicles for a new refueling system.

 

Foreword:
So, as I have eluded, i was not satisfied with my Venture Star-esque SSTO performance. It was too inefficient as it could take up a max of 2,5T hydrogen and 4t methalox. Which means it would take 4 tours to fill one tank. I wanted a vehicle that could fill a tank in 2 tours - meaning I would need to do staging. I also wanted to be, quote on quote, "One Of The Cool Boys" and land my first stage again. But unlike Elon, I don't hate wings and re-entering as a plane, so i tried to make a space plane upper stage.  The problem is the hydrogen tanks. they are quite big.. and they don't look like they will do re-entry that well. So I have tried to do a design for re-entry as a capsule.. flipping around.. and then land as a falcon... I already foresee 2 issues.. it will probably not fly with the heatshield forward because the engines are too heavy... But I already have alternate plans for how to fix that. Yesterday I completed first test run of the spaceplane 2nd stage.

Mission Tasks:

A. Reach outer atmosphere with Stage one and Seperate at ~1000Δ left - Success
B. Boost stage 2 into a suborbital path with a high apoapsis. - Success
C. While Stage 2 coast to its AP land stage 1 - Failure
D. Land Stage 2 at KSC - Critical Failure 

Lessons learned; Lessons Identified:

A. The craft is controlable on the way up, even though it's drag is off center because of the "vertical" stabilizers on the space plane (its really ~45°). When the craft separates at 1000Δ the craft will get around 1400-1500Δv from the shedded mass - It is enough to make the craft return to KSC - but just barely.. I will probably in the future seperate at 1200Δv - just to give me more room to maneuver.


Here we see stage one after its burn back to KSC and Stage 2 on its high AP sub orbital Path.

B. Second stage has a lot of Δv. The 4t fuel stack is put between two stack separators, as it makes the craft not wanna use the fuel - making sure it is reserved for refueling K.G.01 - how ever it does not have access to the front fuel tank either, and fuel has to be moved. There is mass - drag issues that needs to be resolved.. and it feels silly to bring extra fuel just to have enough mass at the nose. I want the craft to be able to land empty. Craft is reasonable manouverable in space, and has enough power for 12ish hours. (I had to wait for KSC to get out from the night side before attempting landing) So may need solar panels just to be sure.

As you can see - the craft has 1700 Δv in the bottom stack alone, and something like 1200 Δv in the front tank 

Also - there is a weird bug were the game just despawns the stages after a certain point. The only way I could be allowed to keep both stages in the game was by giving the second stage a really high AP, so it would not reach it before I had landed the first stage.


First stage has been landed and second stage is still coasting.

C. I Successfully got the booster back to the vicinity of KSC - landing within the mountain range of KSC is a point of success for me at this point... I have no idea how people successfully aim at a small landing pad from the outer atmosphere... But the craft fell after touch down. I also found that the landing legs bend a lot on touch down - breaking the engines. This could just be because i could not find the sweet spot for a "soft landing" - but even though i tried a 1000 quicksave/quickloads i never got to land it without breaking engines or have it fall over. So i need to extend the legs and or push the engines further into the craft.


First stage on its way back to KSC 

1st stage breaking - As you can see we are having really tight Δv margins.

The stage landed, and fallen - one landing leg broke off... for what it is im pretty satisfied.

Only 6km off the VAB building - So Jeb don't even have to drive that far to pick it up.

D.  The seconds stage re-entry characteristics were as I suspected.. Rubbish. Even though it shows in the VAB that point of mass is in front of point of drag... its not front enough when empty. It will land ass first..  and it glides like a brick. I tried a reload and landed it with fuel in the front tank - it made it have mass enough to stay nose first through the thick parts of the atmosphere - but its so heavy then that it cant really glide.. it just "falls with style" into a big ball of fire. Also i am thoroughly against landing with that much fuel.. its silly to push that much mass to space and not use it. 


Here we see first stage over Kerbin, It sure is good looking - how ever.. i need to think hard on how to stabilize the craft.. and make it glide well enough that it can land. Or give it up.

This is the result of the landing - To hard for it to land in one piece.. but i guess not so hard that there were no pieces to be found.

Conclusion:

Maybe the space plane 2nd stage is a development dead end - I may fiddle with it to find better flight characteristics.. After all it has a lot of Δv - so i can reduce its size and that way make it more controllable - I wish there were Hydrogen Tanks in a more aero dynamic way, because they are all cylinders - it "forces me" to go with a cylindrical style of vehicle - or i guess i could design a vehicle that will glide for the methalox refueling, and a vehicle that lands like a falcon rocket for the hydrogen.. It just goes against the utilitarian nature of the crafts. I'd like one solution fits both fuel types. 

We will see what the future brings. A band aid is this - I can land the 1st stage, and i can get the 2nd stage to orbit at the same time. So i guess i am having a foot in the "cool guys" room. 

Stay Tuned for more!

Edited May 22, 2023 by BechMeister
Re-added images

[Sylvi Fisthaug]

On 3/27/2023 at 1:44 PM, BechMeister said:

currently only clock 80-ish hours in KSP 2

How many hours have you clocked in KSP 2 now? 

I started a new space station, as the part count of the other one dropped my FPS to about 7. Made a new iteration of the stolen tugs for that one. 
Image is in spoiler (to not draw away attention from your own posts.)

Spoiler

I must say, your thread here have inspired me to build the stations. I thank you for that.

Edited April 28, 2023 by Sylvi Fisthaug
expanded post

[BechMeister]

6 hours ago, Sylvi Fisthaug said:

How many hours have you clocked in KSP 2 now? 

Last I checked I was at 200+ But its not accurate.. Because a lot of the time the pc will just be running with me doing other stuff. Especially because i have two kids. A daughter turning 5 here in may, and a 2½ year old son.  Also.. I feel a significant portion of the time is spend on loading from saving/quicksaving x) - But i have been a closet KSP player for a while, I just never had the abilities to get into KSP1 as I never really knew were to start, thats an advantage in KSP2 - there are fewer features, so its easier to pick a goal, for me at least...
 

6 hours ago, Sylvi Fisthaug said:

I must say, your thread here have inspired me to build the stations. I thank you for that.

I am really happy I did! It looks good. what are the small squares on the cylinder that holds the solar panels?  

[Sylvi Fisthaug]

 

8 hours ago, BechMeister said:

I am really happy I did! It looks good. what are the small squares on the cylinder that holds the solar panels?  

Thanks! It's what left of the struts I needed to launch it 

8 hours ago, BechMeister said:

Especially because i have two kids.

It's really impressive how you managed to build all this with two kids! 

8 hours ago, BechMeister said:

thats an advantage in KSP2 - there are fewer features, so its easier to pick a goal, for me at least...

This is true, and the goal of the developers is to invite new players in and make it more accessible. This thread is an example of that. Lots of the old players keep rambling on about the state of the game, the lack of the features, how they dare launch KSP2 with fewer parts than KSP1 after ELEVEN YEARS of development... fewer features = new players.

[BechMeister]

21 hours ago, Sylvi Fisthaug said:

Thanks! It's what left of the struts I needed to launch it 

They give a nice "texture" to the station xD

- Well its a pretty easy game to play with kids - Most of the time it does not need a lot of input unless you use time acceleration and there is no gore or horror in it. So the kids can watch. They think its fun just to point at stars, ask question about earth and the universe etc. Also a good visual reference for how the day night cycle works x)

 

21 hours ago, Sylvi Fisthaug said:

This is true, and the goal of the developers is to invite new players in and make it more accessible. 

I guess thats also a reason why I make this blog, and bug reports. I want the game to get as good as it can

[BechMeister]

//////////MISSION UPDATE\\\\\\\\\\
- Fixing flight characteristics of 2 stage reusable Methalox Glider -

The new protype refueling vehicle docked at K.G.01 refueling the Methalox tanks.

Foreword:

I really thought i could have made a update saying i was done with the new refueling vehicle. But alas, After tinkering and testing it is still not re-entering well.. And i dont know what else i can do at this point. Which means it looks like a developmental dead end.

Mission Goals:

A. Fix stability issues for Stage and Test RCS charactaristics + Δv Margins. - Failure
B. Fix stability issues for Stage 1 - Success


Lessons Learned; Lessons Identified:

A. Making a better launch vehicle: 

Prototype A:

I tried to fix the mass to drag issue on the 2nd stage by replacing the rear fuel tanks with medium tubes. I also decided to put a cargo bay, with a docking platform in it to avoid drag and move more mass forward that wasn't wasted fuel.


Prototype A after first test flight. The fuel tank within the two stack separators is the "cargo" - The craft will not be able to take the fuel by accident when its between two separators. Between the rearmost stack separator and the engines is an empty tube - hence the fuel lines, as the craft would not fire the engines without. The craft flew up into the air from the runway, glided down and landed.

Prototype B and C:
When i launched protype A for a orbital test I found out that it calculated the fuel in the cargo stack into the total Δv pool. Which mean that I thought I had ~1500 Δv available. but in reality it was less than half. So prototype A never got to Orbit. 

I then tried to add a short stack behind the rear stack separator. Keeping the empty tupe there for the wings. It had just enough Δv to get to orbit, but not enough for rendezvous and de-orbit. Which mean i reverted and ended up putting a big fuel stack. and no tube. The VAB still showed that the point of drag was behind the point of mass. So i prayed it would be enough and tested the vehicle.


Prototype C ready for test flight.

Stage separation at ~1300 Δv, altitude 38km

The "Proof of concept" flight showed that separating at 1000 Δv was a little to tight for comfort when coming to landing - so i aimed for seperating at 1200 Δv but in reality hit closer to 1300 Δv.


As you can see, once the stage 2 had separated, the shedded mass bumped the Δv up quite a bit. 

I had a weird bug that kept me from trying to land both stage 1 and orbit stage 2 in real time. It was like an invisible tether were attached to the craft and kept it from pointing retrograde. I made a bug report with my findings and decided to go forth with the rendezvous and refueling.

It was a astounding success. I had just enough Δv to make the rendezvous and de-orbit manouver. The RCS is a bit sluggish.. but it is a lot of mass to push with 4t fuel. In the end it was alright. The fact the vehicle moved slow made it easier to dock. And wow.. hitting the docking pole with the internal docking port is so much easier now that i have found out you can press the speed to get your relative speed and direction to the target.


 Prototype C on final approach.

Prototype C lining up for docking.

Prototype C docked with K.G.01

An important lessons learned is that you need to transfer power in the resource manager. The craft had enough battery power to circle the plannet the times it took to get a window of opportunity to rendezvous. But the power was spent in the subsequent orbits around Kerbin, while waiting for KSC to be on the day side. I just assumed it would be recharged with the rest of the systems.


Prototype C still in correct orientation in the upper atmosphere.

But as soon as the craft hit the thicker atmosphere, it would flip and fly ass forward. The crafts stability had not been resolved.

The craft did not hit the runway at KSC. But was landed - after it got bellow Mach 1 it regained controlability. - How ever.. once re-entry heat is introduced. I doubt it will survive the atmosphere.
 

As you can see the Stability issues were no resolved. I was sitting with a feeling that the VAB is not telling me the truth.. and tbh, I have had 3 different readings on mass/drag relationship. As seen here:

Reading A:


I suspect this is the true reading. As it reflect the fact that the ship would go nose first, then flat spin and in the end just barely doing controllable flight and landing.

Reading B:


This was what i thought I had to work with, maybe still overly optimistic to expect this to fly head first. As the center of mass is still 2/3rds to the rear.

Reading C:


This is the most optimistic drag reading i've had. but it also pulls weirdly to the right.

Conclusion:
I am was extremely happy that this design made it to orbit, docked, refueled. But as utterly disappointed it didn't land - The first stage is at the limit of what it can push up. I cannot add more fuel to it, it only loses Δv if I do that - So i can't really make stage 2 much heavier. 

I have 2 more idea's as to how i fix my heavy ass problem:

1. Reduce to 2 Aerospike engines - this will give it a Trust to weight ratio of 1.07 - but stage seperation happened at 38km - meaning a vehicle with Trust to weight ratio <1  could maybe get to orbit?
2. Maybe replace Aerospike with a lighter engine but less Trust to Weight.
3.  Find a way to make a pull design, rather than a push design... Or some convoluted way to move the engines from the back to the front of the vehicle... Some cargo bay, drone parts, shenanigans. - although this probably will become a more complex vehicle than what its worth.
4. Redesign the nose part with fuel tanks rather than an empty nose cone stuffed with batteries and monopropellant. 

If nothing I must accept this is a dead end - and make a capsule style stage 2.


 

Edited May 17, 2023 by BechMeister
accidently posted half the post before it was done

[BechMeister]

B.

The fixes to Stage 2 was all successful - as I said i had an issue were i could not use my save game with the stack seperation to test if the 1st stage could make it back to KSC. So i boosted the stage up trying to hit the same Δv Margins and altitude. I then did my return burn, and "landed" the stage  in the mountains to the West of KSC.

I found that with 1800 Δv Its still very tight. And i may have to stack seperate with 1400 Δv left. - Presumable this will give me ~2000 Δv to return.


Stage 1 on the way back to KSC - as you can see, already from here its clear it will not hit the mark - I have a really hard time to gauge how much I need to take the planets rotation into account. 

Doing a break burn with landing gear out, right before touch down.

Landed without breaking the engines - but as you can see.. it landed on very uneven ground, meaning it fell imidiatly.

Jeb had a bit longer drive for this one.

 

Final Word:

I was a bit discouraged by the result of todays and yesterdays evenings work - I feel i've done what i could to make the 2nd stage have a propper drag/mass distribution... I may fiddle a little bit more with it. Just to see... Its bittersweet. To be this close, yet so far.

[fulgur]

If your craft goes into a flat spin when re-entering, try to pump any fuel remaining into the forwards tanks; that usually works for me.

It looks to me like you have the big inline docking port in the middle and the engines at the back, which moves a lot of your weight towards the rear of the craft. What happens if you make the rear wings bigger / the forwards canards smaller?

[Sylvi Fisthaug]

8 hours ago, BechMeister said:

They think its fun just to point at stars, ask question about earth and the universe etc. Also a good visual reference for how the day night cycle works x)

Holy moly, your kids will probably end up as engineers at SpaceX. Anyhow this warms my heart.

 

1 hour ago, BechMeister said:

that i have found out you can press the speed to get your relative speed and direction to the target.

How have you even been able to dock. I'm gonna blow your mind: select the docking port on other vehicle as "target" by right click, and right click your own docking port and select "control from here". 

Look at your navball. Try to align your craft somewhat in the same attitude as the station. This is easy if you align the station to like anti-Normal or Normal, as this does not change while orbiting. Align your own craft the same way. 

Now just translate your craft IJKL until you have the target in your crosshairs. Move forward at about 1.0 m/s, and try to keep the prograde marker at the target with the IJKL keys. 

And now you have docked! 
But you probably knew all of this from before? 

1 hour ago, BechMeister said:

To be this close, yet so far.

@fulgur made great points just above. 

But why wings and space planes? Will your rocket be able to fly, let's say, without wings? Or just "fins" in the front like the falcon and starship? 
This way it should reenter engine first and not nose first. 

[BechMeister]

9 hours ago, fulgur said:

If your craft goes into a flat spin when re-entering, try to pump any fuel remaining into the forwards tanks; that usually works for me.

It looks to me like you have the big inline docking port in the middle and the engines at the back, which moves a lot of your weight towards the rear of the craft. What happens if you make the rear wings bigger / the forwards canards smaller?

Problem is i try to do re-entry "empty" - you know as fuel efficient as possible. I have a mindset that is "If i have more than 100 Δv left when i re-entry I should remove that fuel" - you know.. No reason to push more into orbit than necessary. - But on my proof of concept, i could make it fly head first by pumping fuel up front yeah. But then it was too heavy to glide x) It fell like a brick. I could increase the wing size though.. but i would rather make a new design, than design it to fly with fuel as counter weight.

Ill try play with wing size - I am just afraid of putting to much drag on stage 2. I can ofcouse add more drag to stage 1 to counter it. Ill play around with it. Thx for the sugguestions.

@Sylvi Fisthaug I used to dock by just burning prograde/retrograde - normal/anti-nomal - radial in/radial out to the orbit. and look if the pixel on the station moved left/right or up/down - and if the distance to target was decreasing. - I even made a post for suggesting a feature  were you would have local/anti-local like in Flight of Nova. Where this nice chap then said it was in the game.. but he did not tell me how to get it to show. 

Since nothing on the Navball UI outside the buttons for SAS and RCS looked clickable - and the design of the Navball UI didnt have anything indicating pressing on your velocity would make it toggle between Orbit/Ground/Target - I didn't think the game had it.. which to me came as a shock. After i was told it was in the game.. i tried to see if there were a hotkey i could press.. there was not.. and in the end i just tried to press everything on the NavBall and found it by chance.

After that docking became a lot easier. Its so much easier when you prograde turns into "local/anti-local" x) - But yeah... First time i docked the refuel SSTO - I eye balled it.. and it was near impossible. This was the first time I docked on that docking port after i toggled speed in relation to target... and my remark was on how much easier it was docking now xD

- Yeah, Fulgurs advice is the only thing that probably can save this craft. But... Like stated above. I'd rather make a new craft than fly up with more fuel than i need. I guess you could argue that if i use the fuel as ballast it is needed. But I guess you get what i mean.

The wings are because i land it as a plane - As you can see I am not very skilled at landing the craft as a falcon 9 - the first stage which comes in at a much lower velocity than stage 2 I still generally am 10+ km off the landing pads. But I've become pretty good at gliding the stages in. 

Also if I fly up with fuel needed to do the flip maneuver and landing. That is more fuel i could have refueled the station with. But my plan B, if i cannot get the glider to work... is something like starship... except the game does not have the tools to make the wings that control the orientation down. So i would probably have a heat shields front. I would probably use the inflatable one. So i can pump it up in front of the engines on re-entry and then make it small once down - then use the engines. 

But i'll give the glider one last go. I had some ideas on how to move more dry mass forward on the craft, without making it longer and to much heavier. Any way.. thank you for your suggestions ^^

Edited April 30, 2023 by BechMeister

[Sylvi Fisthaug]

53 minutes ago, BechMeister said:

But i'll give the glider one last go.

Yeeees, give us more engineer's reports and project updates of your gliders/shuttles. I have learned that the MK3 with a bunch of stuff attached to the front node in the cargo bay flies pretty well. Small cargo bay with a metric dump-ton of batteries and a docking port in the front, tanks in the rear. 

1 hour ago, BechMeister said:

I used to dock by just burning prograde/retrograde - normal/anti-nomal - radial in/radial out to the orbit.

HOW DID YOU BUILD A SPACE STATION LIKE THIS

 

Have you not had any Kraken attacks while assembling?

[fulgur]

Something looking like the Space Shuttle tends to work quite well. The Shuttle cockpit is nice looking and quite heavy on the front of your craft. Of course, it is very hard to launch asymmetric Shuttle-looking craft; in KSP1 I also have had a lot of success with big, Mk3 refuelling SSTOs.

Spoiler

 

[BechMeister]

12 minutes ago, Sylvi Fisthaug said:

HOW DID YOU BUILD A SPACE STATION LIKE THIS

My procedure was this: 
1. Get craft to orbit.
2. Make a AP 100km higher than target AP and a PE 10km lower than the target PE.
3. Wait for 1A and 1B to be somewhat close. Burn radial in or out until the 1A and 1B were <1km
4. When <10km from target - Radial in/out and retrograde to match orbit plane and target speed.
5. Then I would use the map to check my relative speed to target, and make short burns radial in/out, Normal/anti-normal. until i had a relative speed on <50m/s (I could see that by hovering the mouse over 1A or 1B.
6. Go over to RCS and try get a relative speed to ~10m/s
7. Go over to visuals. and then, using my craft as a point of reference, i would pixel hunt... If the target moved a pixel left, i would rcs thrust left if the target moved up, rcs thrust up. And i would make sure the distance to target (seen on the target) was going down. at a not to quick pace. 
8. Once target was <100m i would try park my rocket next to it.. by having the distance to target be constant, and it not moving left/right up/down.
9. Tug drone would disconnect from station, move to rocket. pick up part (which now had a lot less mass to move around) - then i would move it to the point were it had to be connected... make sure i did not move pixels left/right up/down. Then i would turn off RCS - hit "point at target" (which i had set to be the docking port i was trying to aim at). Then i would lock the trajectory. (this is because i have bad results when ever i have RCS on while making the vehicle point at target) Then i would turn on RCS again and boost towards the docking.

- I think this was one of the reasons i was very careful with RCS thrust placement.. and generally only use the single boost point now. The 4 directional RCS thruster is just not behaving like i want to. It was very important that the craft didnt pitch/yaw when i made movements left/right - up/down. and then.. patience, steady hand and slowly.. i build it xD

Also.. making the medium ports hit medium ports is not that difficult... but I dont think i would have been able to do it with the micro ports on the emergency craft without the navball set to target.

 

1 hour ago, Sylvi Fisthaug said:

Have you not had any Kraken attacks while assembling?

Yes. but not since patch v0.1.2.0 - There is a visible cracken issue on the station right now actually. On a early build i made fuel lines go from the fuel tanks - through the trusses etc. for flair... you know.. so you had visible fuel lines going through the station.. but the fuel lines bug out. They disappear.. but sometimes if you connect something where it doesn't disappear. And then all the fuel lines that has disappeared will connect to that one. - and i'm not sure about this... but my station looks a bit bendy, and it has a tendency of starting to start flexing if the SAS system is on.. and i dont know if that's the fuel lines messing up.

I have since removed all aesthetic fuel lines - and the fuel tank that causes the bug will be the first to be disconnected and moved to K.G.02 - and replaced with a fuel tank with no fuel lines on it.. and then i hope that bug is gone x)

Other then that.. the bugs i get is undocked crafts that are are still stuck to the station.. but nothing that can't be resolved by a quick save and quick load.. And the occasional that when i undock a craft and de-orbit it.. the station will de-orbit with it. I believe you experienced the same bug with your station? But i quick save a lot.. so i seldom lose progress x)

 

 

1 hour ago, fulgur said:

Something looking like the Space Shuttle tends to work quite well. The Shuttle cockpit is nice looking and quite heavy on the front of your craft. Of course, it is very hard to launch asymmetric Shuttle-looking craft; in KSP1 I also have had a lot of success with big, Mk3 refuelling SSTOs.

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dont know why but.. Mad Battlestar galactica vibes x) but yeah... but the shuttle parts will require a lot bigger craft. Also my space station is only really made with medium sized parts and the shuttle is xl right? - I think the station would be dwarfed by the shuttle xD - but ill tinker around.

[Sylvi Fisthaug]

12 hours ago, BechMeister said:

but my station looks a bit bendy, and it has a tendency of starting to start flexing if the SAS system is on..

12 hours ago, BechMeister said:

(this is because i have bad results when ever i have RCS on while making the vehicle point at target)

SAS in this game is not very accurate, but unpatched it just rocked the craft around. It is milder now, but it is like a Kraken that kinda nudges your station a bit, happens to me as well sometimes. 

Fuel lines sounds very cool! I considered doing the same, but the reason I built a new station was that the part count of the old one, which was just designed bit by bit, got out of control... the new one I designed in it's entirety in the VAB and launched in bits.

[BechMeister]

17 hours ago, Sylvi Fisthaug said:

SAS in this game is not very accurate, but unpatched it just rocked the craft around. It is milder now, but it is like a Kraken that kinda nudges your station a bit, happens to me as well sometimes. 

Fuel lines sounds very cool! I considered doing the same, but the reason I built a new station was that the part count of the old one, which was just designed bit by bit, got out of control... the new one I designed in it's entirety in the VAB and launched in bits.

Nah - But what can we do - we need SAS xD I turn it on and off when i need it and dont need it.

Also.. i would advice not to use fuel lanes as of yet.. they are pretty buggy.
 

Development Update

1st Stage_Prototype.C with 2nd Stage_Prototype.D right before seperation.

Mission Goals:

A. Make Stage 1 more responsive and Draggy. - Success
B. Redevelop Stage 2 and fix stability issues. - Failure

Lessons Learned; Lessons Identified:

A. I had discovered that the power from the RCS thrusters were a bit lacking. It took quite a while for them to turn the first stage around which meant it would cost longer than it had to before turning back. I also thought the 4 horizontal wings (my poor grid fin imitation) could make more drag. Furthermore after the 2nd stage had been redeveloped - the wings had to be redesigned on the first stage.  - It was a successful! The stage hits terminal velocity at 960-980 m/s which means it should be possible to not have it burn up?

I also tried to do stage seperation at ~1500Δv to see if that would make it easier to land back at KSC. It did.

Δv with pre 2nd stage separation and post 2nd stage separation.

1st stage en route to KSC.

1st stage successful landing without breaking anything. 

And within the mountain range - what i see as a successful landing. 

The Δv margins are still tight though - I spend the last Δv on touch down - meaning i had no more fuel than I needed. I did also maneuver a lot more to be sure I would hit KSC. So with better maneuvering it should be fine.

B. 

I was making a complete redesign of the stage, when i tested the weight of empty fuel tanks - they are not as heavy as i suspected. Which mean i reverted back to the old design, but changed the wing shape at the advice of @fulgur. I went with the very efficient but weak terrier engines and a Thrust to Weight ratio of 0.6 - It is possible to get to orbit with the engine, although it takes a while. It meant i could reduce the fuel needed, and replace the space with a 5m empty tube connecting the engines to the rest of the craft.

I went for a lighter docking port construction. The D model ended up looking like this:

This is first test flight - it flew like a brick, but it was steerable and controlable. So i decided to go forward with the project - I wanted to first figure out if it could get to orbit and rendezvous with K.G01 

Here we see the 3 terrier burning after separation. The craft were so "slow" it was relatively easy to adjust the angle to K.G.01 and the orbit. How ever i found out that the 3 small reaction wheels in the nose were not strong enough to fully control the vehicle. Also I experienced 1 Krakken attack when i used time acceleration. I guess putting 3x Z-1K batteries ontop of 3 small reaction wheels and 2 monopropellant tanks in the nose asks to summon the kraken.

Prototype D in orbit.

Prototype D at rendezvous.

I messed up the rendezvous a bit. So got into a stable orbit 3.6km away from target, and proceeded to burn with RCS thrusters. I had around 224 Δv left, and was afraid to use main engines to adjust. In the end i had to because i spend half my monopropellant getting within 1.5km 

Prototype D docked at K.G.01 doing refueling of the station.

I had only around 20% monopropellant fuel once I was within 100m of K.G.01 - and i actually managed to run out of Monopropellant just as i had done the last adjustment - luckily the trajectory was correct. and the craft coasted the last few meters with 0.5 m/s relative to the target. 

After unloading the 4t fuel the ~200 Δv increased.


Unfortunatly the landing didnt stick. The craft was flying nose first for a good while at a gentle 20° angle of attack, when it nose dived. It didn't flip though! It stabalized itself at this inclination:


Once at sub 900 m/s it feel into a flat spin i could not recover from. For some reason when i got it under control and were building velocity in a dive, it went into a uncontrollable roll, which would turn into a flat spin if tinkered with. The model never recovered and was smashed into a mountain side.

Moving Forward:

I know the vehicle can do what i want it to do now, I will try move docking port forward (provided its heavier than an empty fuel tank) and add a medium reaction wheel to the front (which should also move dry mass forward) and try again. K.G.01 is now fully refueled.. So i think ill Yet what will be prototype E into space empty and see how it re-enteres.

Stay tuned for more!

[BechMeister]

Development Update:

Model E on its way to re-entry test. Notice the angling of the wings - its first time i've really angled the wings to get better lift characteristics. 

Lessons Learned; Lessons Identified:

This mission only really had one goal - test the model E's re-entry characteristics. I found out that the docking port assembly was weighing 0.4t and the two button fuel stack was clocking in at 1t empty. So it did not make sense to swap the stack order. The medium reaction wheel also added good mass to the front of the vehicle. (the black band) and a reshaping of the wings - shorten to move the point of lift further down the vehicle, and thickening it for more lift. I also played with angle... the VAB would change the direction of lift at very tight margins. Any way. The result is a relatively stable vehicle - a bit nose heavy now actually... as strange as it sounds. It really wants to fly prograde.

I boosted the craft to a speed of 2000 m/s and allowed it to do re-entry at a gentle AoA of 20° - The craft wanted to point prograde, so efford had to me made to keep it at 20° AoA. but it was not impossible. The vehicle even got to bounce off the upper atmosphere until it had fallen to a velocity of 1000 m/s - I then took of the gloves and did an aggressive dive down to the thicker atmosphere. The vehicle was responsive and after finding a suitable landing place an, elbeit bit hard landing was made. The vehicle landed up hill.


Model E in an aggressive dive - No flat spin or ass first - it was very stable, albeit a bit nose heavy.

Model E gliding towards a stribe of land, suitable for landing.

Model E safely on the ground in one piece.

Showcase of Model E's contstruction - Black band is the added medium reaction wheel. Grey area is the 'cargo' - 2t methalox to refuel the station with.
Everything bellow the enclosed docking port is empty tube and wings.  

 

Further development:

I am really happy it finally panned out!

I may fiddle a bit with wing shape to see if i can hit the sweet spot were its not so nose heavy, but also not flat spinning. If nothing comes of it. Model E will be the finished model. Then a Hydrogen version is going to be developed that can fuel K.G.01 hydrogen tanks. A version for launching small payloads may also be made - replacing the fuel load with a cargo bay to launch small satelites for a ComNet

 

Edited May 2, 2023 by BechMeister
The setup of text and images had shifted

[Sylvi Fisthaug]

On 4/28/2023 at 2:10 AM, Sylvi Fisthaug said:

I must say, your thread here have inspired me to build the stations. I thank you for that.

My space station is now complete! 

Spoiler

(I was not able to use "insert from URL"-function to post the images, so I just copied and pasted them here. Let me know if you can see the pictures.)
(Mods: if this posting of images violates a rule on the forum, let me know and I will delete them.)

I think I will start my own thread with some screen shots from building it, kind of inspired by yours. 
I feel like I don't want to post more photos here of my own creations  I don't want to take away attention from your own posts.
Let me know your opinion of this topic. 

[BechMeister]

On 5/5/2023 at 1:51 AM, Sylvi Fisthaug said:

My space station is now complete! 

  Reveal hidden contents

(I was not able to use "insert from URL"-function to post the images, so I just copied and pasted them here. Let me know if you can see the pictures.)
(Mods: if this posting of images violates a rule on the forum, let me know and I will delete them.)

I think I will start my own thread with some screen shots from building it, kind of inspired by yours. 
I feel like I don't want to post more photos here of my own creations  I don't want to take away attention from your own posts.
Let me know your opinion of this topic. 

Congratulations! It looks great. I have myself been thinking about using the sphere shaped tanks for K.G.02 (my future Mun station) - but i've been wondering how you get them to space? just a standard over the top KSP rocket? - I imagine if you were to build something similar.. you would build it in space?

Any way, when you start your own blog. Send a link x)
 

//////////MISSION UPDATE\\\\\\\\\\
- Updating K.G.01 to have Synergy with K.G02 fuel amount -

K.G.01 getting hot fix to an logistical issue brought up by limitation of the development of the service vehicles.

Forword:

Do I have an update for you! So as you may have read, i had quite some issues with my 2nd stage on my service vehicle. Once I had those fixed i quickly went to develop the version of the craft that needed to supply the station with Hydrogen - the fuel i've picked for interplanetary travel and have yet to use. 

I quickly found a problem though. The 4t Hydrogen tank being L was too big to fit in my small 2nd stage glider. It bugged me a bit that i would need two different vehicles as i like the modularity, simplicity and that things are utilitarian. I was contemplating ditching the glider for a vehicle that could get both Hydrogen and Methalox to the station. How ever making a vehciel that re-entry like a capsule and land like a falcon 9 - Or early dragon capsule -  meant a vehicle that was 44t. As a reference the glider is 25t and at the limit of what the 1st stage can put into space. Which meant that I would also need to make a new and more powerful 1st stage.

Alright - I ditch the large hydrogen tank and go for medium - but that had a second problem connected to it. The medium hydrogen tank is a 2.5t tank. Meaning that it didn't add up with my 8x 8ton tanks. It would take 4 tours to fill a tank 100% and the last tour would only send up 500kg of the 2500kg. Meaning 1 out of 4 tours would be inefficient. But If i could install 2 more tanks on K.G.01 I would solve the problem, as I would have 10 tanks on the station, and that would be a multiple of 2.5t.

So before me lay 2 paths:

1. Design a new 2nd and 1st stage.
2. Find additional two spots for the 8t Hydrogen tank mk.1 And develop a Hydrogen glider.

Like any sane man I opted for a makeshift solution to add more space on K.G.01 - I figured i could put an addition on with 4 medium ports and move Coms and solar panels to that, and install two addition tanks in line with the rest of the station as seen here: 


K.G.01 with new Coms/Power tower - Two additional medium ports are present which can be used to add heatsinks once they are added to the game.  2 extra hydrogen tanks have been installed in line - keeping the design esthetics even though it was never planned to hold 10 tanks.

I think the result turned out nice, It was also a great opportunity to install an adaptor plate for the Tug Drone so it could be moved to the end of the station, rather than hanging on the M.Leo's taking space. - It makes for a nice symmetric look.

Installing two tanks also gave a golden opportunity - by installing a tank with 2.5 t fuel missing - I could fully test the Hydrogen glider in development.
 

//////////MISSION UPDATE\\\\\\\\\\
- Developing Hydrogen and Satellite Carrier Glider -

Hydrogen Glider:

Left to right: 1. Satelite Carrier with 8 ComNet Satelites 2. Hydrogen Glider. 3. Methalox Glider. (the grey band is the cargo)
 
Getting the point of drag and mass propper adjusted on this vehicle was far more easy than on the methalox version, solely for the fact that the Hydrogen tanks are very low mass when empty, and gives a longer body for installing wings. - I still shrouded the tank in a medium tube... the hydrogen tanks looks very draggy and not like it will do re-entry well once heat is introduced, so now it's covered.

How ever - during this project i discovered the numerous Δv bugs there are in the VAB. I had a lot of issues figuring out how much Δv my stage had. These coming images are good examples as to what the issue was: I had two bugs going on - One is a already known bug were the VAB apparently have trouble figuring Δv when using multiple engines? Any way, I also found out that if you place a decoupler between two tanks, and connect them via a fuel line - I got double the Δv number i had.


Here I have two different Δv readings - and neither are correct.

Or here with extra fuel on it - it went from 1970/839 to flat 1041 Δv

If I seperated the two tanks with a decoupler and connected them with a fuel line, i could some how double my Δv

This bummed me out big time - for a while i thought I had accidently found an exploit when i put two decouplers between the fuel tank I didn't want the game to draw fuel from - to avoid having to spend time checking if I still had the cargo fuel with me.. or I accidently used it to get to orbit. If it was an exploit, it would mean i was back to square 1 developing a new craft.. since i figured it would only be a matter of time before the exploit was gone.

How ever @Streetwind was super nice and helpful and walked me through the rocket equation calculate my Δv - I am not very math savvy - but he explained it so even i could understand it. 

I'm gonna put it here if others want to replicate it:

Rocket Equation: (symbols stolen from wiki)

Δv= I_sp * G₀ * LN(m₀/m_f)

To figure out my Δv for the second stage it looked like this:

I_sp = ISP for the engine(s) in vacuum.
G₀ = Standard Gravity
m₀ = Vehicles Mass with fuel spent (its weight when it reaches orbit) 
M_f = Mass Full.

I did not know of this and Streetwind explained it so it was really simple to understand. I plugged my numbers into google and it ran the calculation.


Which shows that the Δv for the stage was neither 1041, 2609 or 839 - but 1981. Enough to get to orbit, rendezvous and de-orbit. Fantastic - After spending an entire evening and morning trying to figure what's what - I can now just double check if the game runs the math right. I was ready to finish the mission:

Mission Tasks:

A. Get Hydrogen glider into orbit, rendezvous with K.G.01 and Dock - Success!
B. Refuel K.G.01 and De-orbit - Success!
C. Land back at KSC - Success!

Lessons Learned; Lessons Identified:

It was an astounding success - I kept keeping an eye on the Δv - and it did seem to go down slowly. At one point I had 111Δv left and the maneuver required 83Δv - but once the burn was complete I still had 63Δv - a clear proof the game was showing me less Δv than I had.


Hydrogen Glider approaching K.G.01

Glider right before docking with K.G.01

K.G.01 and Glider docked - refueling engaged.

B. Even thought he glider claimed to only have 63Δv left after shedding wight from refueling - I knew it had more. The maneuver node only allowed me to get into the atmosphere - were it ultimatly would have lost enough speed through drag to not go back into space - the craft had more than enough to enter a suborbital path.


Glider at a 45° AoA breaking in the upper atmosphere.

The craft was very easy to steer through the atmosphere. It was a joy to do left and right turns at 45° Angle of Attack without any stability issues to wiggle down through the atmosphere, and not bounce off it. Once the craft was sub. 1000 m/s I lined up KSC and "glided" (at least just as well as the shuttle did) the last bit down.

Glider extending the glide to line up with landing strip at KSC - visible in the right side of the shot.

C. The craft glided down at 45° and flared up for a soft landing - no issues. It glides like a brick - but it has no flat spins or other stability issues:

Glider doing its 45° inflight to KSC.  

Glider flaring for a soft touch down as the landing gear comes down - at this point the craft is only moving at 45-50 m/s - meaning you have to time the flare maneuver to not stall out and crash. But its quite satisfying to do so - and not that difficult once you've done it a few times.
 

Conclusion:


Glider back from space on KSC - First 100% successful mission in re-developing service vehicles for K.G.01

Well - that marks the end of a lot of hard work making a fully reusable system for keeping K.G.01 fueled and operative - It also marks the time to move on to mission 2.
Establishing a CommNet. You mave have noticed the satelite deploying version of the glider in a previous image, here it is again:



I asked about antenna strenght etc. Did not realize that Mm means Mega Meter and not mili meters - which explained a lot about the range of the small antennas - I figured that a small antenna satelite placed in a Medium Eleptical orbit would surfice, and then 4 bigger satelites in a Molnya or Tundra orbit for reaching outside Kerbin. 




I know KSP stock does not require you to use very specific orbits like Molnya to keep them in the same path - but I dont want all my stuff to clutter the equatorial path, and it seems like a fun exercise - Also I dont have to be too precise. I have seen stratzenblitz 75 movie on how to equally space your satelites, and will try see if I can make the math work - as said previously... im not very good with math. But I know if i can launch a satelite at 7/8ths the orbit I should have 8 satelites evenly spaced around Kerbin... Now its just a matter of doing it practically. 

Any way! Stay tuned for the beginning of Mission 2: Establishing a ComNet around Kerbin and the Mun!

Ps. I have been contemplating uploading the vehicle files to this blog - now that stage 1 is complete. Would that be of interest at all? 

Edited May 17, 2023 by BechMeister
typos

[Sylvi Fisthaug]

1 hour ago, BechMeister said:

I imagine if you were to build something similar.. you would build it in space?

Ok, so DO NOT send them full of hydrogen to orbit. I docked both the drones together to move it and it was a   H A Z Z L E. 

Spoiler

SO heavy when full.

So I recommend putting them in orbit, rendezvous, and especially docking WHEN EMPTY. Or MAYBE half full. 

Spoiler

So I designed a tug based on the large size of fuel tanks for more beef (other ones on medium and large, but less thrusters and small / small and small / medium docking.
This goes medium / large as you see. And with monoprop engines that I toggle on/off with action groups.

Have only tested it alone in suborbital trajectory, and tried to turn around an XL first stage with like 10% fuel, think it was like 40 tonnes, and it was ok. 
But the tanks are 56 250 kg, and got 50t of hydrogen. So yes. Send them empty.

The golden tanks on KG-01 looks great! The gold foil is so aesthetically feeling. But like, I built another station but had so big a part count that my FPS dropped to 7 FPS on my 3070ti

Now iz 15 and aight. 

[BechMeister]

50t hydrogen. Shez. Maybe its a bit overkill?

It would be 20 sorties from KSC to K.G01 to get the Hydrogen to Orbit - its an "odd number" though - in the sense that they need to do 16 or 32 sorties to fly with 100% full tanks - 40t or 80t hydrogen.

I could add a few extra tanks beside the big 50t tank to get the missing 30t.

 

the tug tours from K.G01 to K.G02 would split into 50/100% of K.G01 capacity instead of a ~62.8% out of 100%. 

50t would be 6-7 sorties from the tug boat between K.G.01 to K.G.02 - but with 80t fuel it would be 10 - nice and round. Still a lot though... 

42 sorties...

 

50t fuel/8t fuel tank capacity is 6.25 though - i could add 3 50t tanks totalling at 200t. meaning tug boat tours would be 25 - and  that would mean 80 glider sorties... so 105 sorties total.. hah damn. And it would prbably be good to have 5 big 50t tanks so K.G02 doesnt have to go to 0% to make the refuel calculation add up. Then when ever there is 20% left its time to start the 105 refueling sorties... 200t out of 250t...haha that would be insane...

Probably better for my sanity just to have 160t - when ever K.G02 is bellow 50% i do 42 sorties 80t moved.

 

I also have a lag problem when im around K.G01 - I would like for K.G02 to be bigger... but K.G01 is at the limit of my computers ability. Especially when you consider that a future multipart/multi vehicle interplanetary vehicle need to be able to dock and refuel too.

I need to be smart about my parts.

Maybe i could move a lot of the infrastructure to the moon itself? Eh.. that would make it all very obnoxious.

 

Any way... lots to think about x)

 

//////////MISSION UPDATE\\\\\\\\\\
- Going down a CommNet rabbits hole -

Edited May 17, 2023 by BechMeister

[Streetwind]

9 hours ago, BechMeister said:

Establishing a CommNet. You mave have noticed the satelite deploying version of the glider in a previous image, here it is again:

Congrats on your space station and refuelling flights, looks great!

But I need to quickly interject before you put a lot of work into something that'll only end in frustration.

That satellite you've shown there? That may well not work for a communications network. I'm not 100% sure it won't work, but given the "sort of there but not really" implementation status of the commnet feature, the probability is high. You really need to run a test before you spend time deploying dozens of these.

It's not that you made a mistake. Given the information available ingame, you chose antennas according to your needs. But if we assume that KSP2 just cloned the KSP1 implementation (or just copied it over wholesale and changed some range numbers), there may be additional factors to antennas that the editor simply isn't showing you. For example, you'll notice that for many ranges, there'll be two antennas - one of which will be significantly heavier than the other, despite there being no difference in stats whatsoever.

In KSP1, that was because not all antennas could actually be used as a comms relay. There were "direct" antennas, which were light and frugal with power use, but could only talk to KSC. They could be bounced through a comms network, but they could never be part of one. There were also "relay" antennas, which had the same range but were heavier and required more power, and only those had the ability to act as relay stations in a comms network.

The Communotron-16S you chose? Not a relay antenna. In KSP1, it wouldn't be usable in a comms network. (And yes, even though it is three times as heavy as the regular Communotron-16. It was an outlier. It had these stats because it was a strengthened variant resistant to aerodanymic forces, for use on planes or re-entering spacecraft, where a regular antenna might snap off.)

Second point, antenna combinability. If you've read the relevant KSP1 wiki page, you may have seen that multiple antennas on the same vessel will add their strength together to increase the vessel's total comms range. Given the much higher ranges on antennas in KSP2, I'm not sure if you actually need to combine antennas for a Kerbin SoI commnet... but just in case this was something you were factoring in: the 16S, being an outlier, was the only kind of antenna that you couldn't combine. Ergo, having two of them on the satellite in the screenshot is just aesthetic, it doesn't actually improve the range.

Third point, antenna strength. Any comms network you deploy around Kerbin will remain almost completely unused. That is because vessels prefer connecting to the strongest antenna they can see. And the strongest antenna around, by a very large margin, are Kerbin's ground stations. They are gigantic, and can draw whatever power they want - so they are orders of magnitude more powerful than vessel-mounted antennas. Any vessel that can see Kerbin will connect directly to Kerbin, always, completely ignoring any and all commsats in Kerbin orbit.

The only time one of your commsats will be used is when a vessel cannot see Kerbin. Meaning, when it is in a Mun or Minmus orbit, and currently behind the moon, so it occludes Kerbin. As a result, what you really need is not a comms network around Kerbin, but rather one around the Mun, and one around Minmus. I mean... you can still build one around Kerbin anyway, for the challenge It just won't do anything.

 

I recommend that you do a test run to see whether these assumptions carried over from KSP1 still hold water in KSP2. Specifically, you should test if your Communotron-16S equipped satellite can relay at all. To do this, put one in a high Mun orbit, and then have a vessel in a low Mun orbit where it will be cut off from connecting directly to Kerbin. See if it'll bounce through the satellite. Use an uncrewed craft for this, so the game will actually tell you when it loses connection.