Duna Mastery Challenge - companion report.

[BechMeister]

Bechmeister's
-= DUNA MASTERY CHALLENGE =-
Companion Mission Report

 

<<<<<<<<<<FOREWORD>>>>>>>>>>

 

A while ago now I was recemented to do OJTs Duna Mastery Challenge:

 

There was only one issue though - I felt my very detailed approach to writing mission reports were not fitting for the challenge post format. 

To me it felt like the challenge format had to be concise and to the point, and not including the failed attempts... design consideration etc. - So I decided I would make a companion mission report to the successes and failures of each challenge. Writing in excruciating detail  - like I guess I have been come to be known for.

I hope that It is not considered in poor taste - I dont want to take the spotlight from the challenge.

I was super impressed by the scope of the challenge - all the steps from building a communication net etc. before sending the first kerbal (even if its theoretically not needed - especially not at the time the challenge were issued, were antennas were only really for visuals)

It all fit right with my own tendency to try add some "roleplayed" realism into the game. I thought it was a great way to go about it with Duna, and decided I would give it a go... (And I hope OJT expand upon the challenge in the future.)

I completed the first step back in February - because by chance a Duna was positioned for a fly by and an window to send a probe to Duna was there.. and I was a bit bored with finishing up K.G.01 and 02 at the time...  and after that I decided to visit Minmus before continuing with Duna (it seemed like a better way to spend the time waiting for Duna to be in position again).
 

Anyway I will be doing the challenges in order - maybe combining steps some times, (if its not considered cheating ). Feel free to join me in my success and failures, with your successes and failures here on this space.. or questions, remarks advice etc. 

<<<<<<<<<MISSION_TASKS>>>>>>>>>

On 2/28/2023 at 9:15 PM, OJT said:

1. Destination Duna

Pretty straightforward: build an Unmanned Probe and perform a fly-by of Duna. Very broad definition of "Probe" here: you don't need to have antennas or means to generate electricity. As long as it has a Probe Core and it fly-bys Duna - you're in

subsidiary goals:

A. develop a reusable satelite carrier. + a satelite with enough Δv to get to Duna. - Success

B. Launch satelite and return 1st and 2nd stage. - Success

C. Perform fly-by of Duna. - Success

 

<<<<<<<<<<< Lessons learned; Lessons Identified>>>>>>>>>>

Goal Post A:

Left - Multifuel glider (Methalox). Right - Prototype of Satelite Deployment Glider (SDG)

The fact that the first mission task were so "easy" - I mean - flying by Duna within its sphere of influence should be a pretty easy task? Just make a vehicle with enough Δv and then some, to make room for rookie mistakes too - So I felt like I had to make it a little more interesting by launching it with a launch vehicle that were reusable.

The easiest thing to do was to take my Multi Fuel Glider from the service vehicles for my Space Gates (K.G.01 and K.G.02.) and tweek it to my needs. Of course it would limit me in how big a satelite I could make - but that would give a fun constraint to design around.

The Satelite Deployment Glider (SDG):

The Multi Fuel Glider is normally carrying a payload of 4t methalox - which meant that as long as the probe only weighted 4t - the flight characteristics should be the same. The most important design goal was keep the center of Mass and Center of Drag at the same place - If not, the body flaps (the 2 AERO BREAKS bellow the rear engines), had more range of motion to balance slight changes. You see - previous versions of the glider had issues were going through the atmosphere with the rear frist - not ideal..

I ended up countering that with 2 aerobreaks I could deploy with a hotkey. When the vehicle was re-entering I watched the SAS - as soon as I could see it the indicators that it used "force" to keep its angle of attack (around 40°), I adjusted the deployment angle of the breaks. The glider became stable at 25% deployed.. So there would be plenty of angle to play with.

The two gliders side by side.

Because I hated the look of the cargo bay doors going through the tail wings - The space available for a cargo bay would be quite limited. To keep the weight as far away from the rear as possible (the reason I have a light tube between the engine plate and the wing section on the original glider) - I decided to place the cargo door between the RCW and the rear fuel bay. (just remember to connect the fuel tanks to the "engine plate" with fuel lines, if you use a tube to separate the the space like i've done.

With the glider made it was time to make a simple probe that would fit within the cargo bay.

 If you want all the details in developing the Multi Fuel Glider - See the block post in the spoiler section:

Spoiler

The Probe:

The limiting size of the cargo bay (being a size medium and rather short) - made for a fun design challenge. To keep the probe within the limits. I knew the probe was going to be small - so a small 48-7S "Spark" would be plenty of power for the smalle probe - and the small size of the engine was also ideal.

I tried to fit a OSCM-01 "Mini Lab" and make a voyager esque probe - but it was hard to give it enough power to be able to collect science and not have balloon in size. In the end I looked at the requirement for the challenge completion - and since it could essentially be a projectile.. I thought it would be overachieving enough just to put a dish on that could reach KSC. So it became the simplest of probe. a core, some solar panels and enough methalox to get to Duna.

Speaking of which - If you're new to the game and you dont know this interactive Δv map, I highly recommend it  It looks like this:

That together with this graph for the optimal transfer position:

 

- makes it a lot easier to plan the vehicles. in the end the probe got look like this:

The craft may be small but it still packs a wooping 1.986 Δv - which should be more than enough, considering it should only take 950 Δv to escape Kerbin SOI + the 130Δv to woosh by Duna. (If I am reading the Δv map correct) - I mean the probe will be doing its transfer burn from LKO. ~80km 

Goal Post B:

The satelite deployment glider burning into a LKO while the 1st stage is burning back to KSC.

As mentioned in Goal Post A - the Multifuel glider that this vehicle is based on is well understod from its use servising K.G.01 (Kerbal Gate 01 - a space fuel station in LKO). The satelite carrier with payload is not slightly lighter than the multifuel glider. So getting to space did not pose any deviation from the flight procedure:

1.  Launch the vehicle.
2. as soon as it is clear of the tower, tilt ~5° eastward and lock prograde
3. allow vehicle to gravity turn on its own - unless you can see you will hit the 45°E mark before hitting the upper atmosphere (band 3) - then hold and before allowing it to gravity turn once appropriate. 
4. Once at 1600 Δv - engine cut.
5. stage separation.
6. orbit the SDG.
7. De-orbit the 1st stage.
8. make sure the 1st stage does not exceed 700 m/s on the way down (the engine plate will not tolerate the heat from higher speeds)
9. Land the stage at KSC. 

All these steps went without incident.

1st stage returning back to KSC.

One thing that is odd though is that even though I copied the vehicle from the K.G.01 service vehicle package - 2/3 nozzle extenders break off on separation on this version, were it does not on the Multi Fuel Glider version.

After the stage had returned it was a simple matter of getting the glider into space - it is very low powered. But it just means you have great control when circularizing the orbit. Here at 80km to comply with the Δv map.

SDG deploying the communication satelite.

After the satelite had been deployed it was just a matter of deorbiting the glider and landing it back at KSC.

The glider is pretty well balanced at this point. My best advice for making space plane on re-entry is that if your ass is flipping up front - or you can't hold your desired angle of attack at on your way down (mine is 40°) - you can add aerobreaks to the tail of the glider - these will function as body flaps and help it hold its orientation. read Goal Post A for more details 

I wished we had dedicated body flaps - it looks alright with the aerobreaks, but an actual body flap would have looked better.

SDG during re-entry - notice the body flaps helping it "keep its nose down".

Another pro tip is to mark the runway with some sort of small rover - it gives good aiming markers and makes it easier to see if your prograde is on target - especially considering that the prograde most likely is a few degrees bellow the direction your flying:An example of the glider aiming towards the runway - the prograde is positioned on the target to make sure I have enough energy for the flare maneuver. 

Half a day later the  glider was back at KSC ready for a refurbish and the next mission.

For detailed slideshow of the mission, see spoiler section bellow:
 

Spoiler

The SDG ready for take off around midday.

The seven S4 KS-25 "Vector" blasting the vehicle into space. Notice that the 4 grid fins are deployed - this is the only thing that keeps this, otherwise unstable "rocket", from flipping.

engine cut.

Stage separation and flip maneuver of the 1st stage. - it annoys me that the spacers break off.

lining up the launch pads on KSC - the 2 control surfaces at the end of the body allows the rocket th glider rather well all things considered. It's a very forgiving rocket to get back to the pad.

3/7 S4 KS-25 "Vector" engines are carefully managing the speed down to the pad.

slowing down.

and landed - now back to the SDG

The satelite is successfully deployed in LKO.

The SDG perform a partial de-orbit burn, just to be sure that it won't be interfering with the satelite while time warping to the correct deorbit position.

Over the desert the final deorbit burn is performed. exhausting the last methalox and aiming at the runway on KSC.

engine cut and coasting phase. - the cold blue and glowing engines.. I never get tired of looking at that.

Cutting trails of plasma through the atmosphere as the sun sets. AoA at 40° and stable.

once through the thick part - the body flap is retracted and the glider aims for the runway.

touch down in the dark.

safely down, parked outside the VAB.

Goal Post C:

Probe arriving at Duna.

It was time for the probe to perform its capture burn to its destination; Dune - Desert Planet...

As seen in my entry in the Duna Mastery Challenge - I did not have an optimal transfer window to Duna. But as you can also see, it didn't matter - the probe had ample of fuel to get it done:

Image of the maneuver node that would bring the probe to Duna.

If I can offer an advice - The game does not display the position markers for the vehicle and target when there is a Sphere of Influence between you and the body you want to intercept..

Let me explain: here we are moving from Kerbin SOI to Kerbol SOI and then Duna SOI - So the markers will only show once you leave the Kerbin SOI.

do the maneuver burn as well as you can from the maneuver node (lets just agree that the maneuver node system in game is not really geared for high precision, I used it more as a guide line.) Once you leave the Kerbin SOI you will get the markers, and then you can fine tune the path until you pass through the Duna SOI. (because you are so early in the process, a lot of the time you can do the corrections with the RCS thrusters - this craft had none.. so it would be with main engine)

From here on it was just coasting pass Duna and wave it goodbye - first challenge succeeded.

The probe performing fly by of Duna.
 

<<<<<<<<<<Moving Forward>>>>>>>>>>>

Challenge one has been complete.

I think I will challenge myself for the future by limiting myself to designing vehicles that fit within the space of the glider for as long as possible.

After my Minmus mission, I am in the mood for something smaller and less elaborate.

Stay tuned for more!

Edited April 28 by BechMeister
added tag: Active Mission

[BechMeister]

-=R&D_UPDATE=-
CommNet - Satelites and the Molniya Orbit

I figured a good way to continue with this blog - would be to alternate between a R&D post and a Mission Execution Post. Where all the theorycrafting on "how to solve the challenge", will be poured into a post first, and then I follow that up with a Mission Execution Post. I have a feeling that a lot of good discussion can come from making a theory and testing if it worked... at least it will give people a chance to say how wrong I am in my calculations and theories - and stop me before I do something really silly  Or better yet.. give people something amusing to read.

Any way - Without further ado - here is next challenges

On 2/28/2023 at 9:15 PM, OJT said:

2. Otherworldly Connection

Build an Unmanned Satellite and enter Duna orbit. Satellite must have an antenna strong enough to reach Kerbin and have means to generate power. Take Ike's SOI into consideration when you plan the orbit!

3. Transmitting Live From Duna

Set up a Relay Satellite constellation in Duna's orbit. There must be at least 3 satellites in the constellation. Each Satellite must have a Relay antenna strong enough to reach Kerbin and have means to generate power. You can either launch new satellites or add some to the one you've sent in Challenge 2, as long as the Satellite from Challenge 2 satisfies the aforementioned requirements

Before we talk about the 2^nd challenge I am going to ignore it for a little while, and focus on the 3^rd challenge first = 3 CommNet Satelites in Orbit around Duna - To me that screams for a Molniya or Tundra orbit. - Something I've been wanting to try out for a while now.

If you dont know what a Molniya or Tundra orbit is - See spoiler section bellow:

 

Spoiler

The Molniya Orbit:

Example of a Molniya Orbit with 4 satelites.

The Molniya and, its cousin, the Tundra orbit are both very elliptical orbits. with orbits that, respectivly, have a period of ½ and a whole sidereal day and at a very specific inclination to the body they orbit (63.4° around Earth)  . The Inclination needs to be this specific  in order to cancel out the "pull" from the equatorial bulge - that otherwise slowly alters the orbit. (the "Fat Earth Theory"). 

Inclination:

You see, the fact that earth bulge at the equator means that it will pull a satelites inclination down towards the equator over time. But at 63,4° - the effect is canceled out. In KSP this is not an issue since all bodies are perfect spheres.. So we can orbit perfectly at any inclination.

Orbital Period:

The other interesting thing about the Tundra and Molniya orbit is the period with which they orbit -namely a Half and A complete Sidereal day. 

A Sidereal day uses the stars in the background as its point of reference, where a Solar Day uses the stars as reference. So roughly speaking - A sidereal day is how long it takes the body to rotate so that distant stars appear in the same location from the night before. 

Why this orbit:

The point of the Molniya and Tundra orbit is to give coverage to the polar regions, that do not have line of sight to geostationary communication satelites. The Polar Region will always be able to see at least 1 satelite in a Molniya or Tundra Orbit.

A vehicle in a Tundra orbit will orbit over the same spot once every revolution, and the Molniya every second revolution.

There are 2 reasons why I am thinking about a Molniya Orbit:

1. A Geostationary orbit will not have Line of Sight to the poles of the planet - and It would make sense for future settlements to be near the poles were there is water ice. So a Tundra and Molniya orbit is necessary for such an settlement to be able to communicate with KSC. (Roleplaying)
2. Since the orbit is highly elliptical, it will be more likely that none of the satelites are hidden behind Duna - which should be able to have reliable coms with KSC with fewer satelites and that there are no signal loss to KSC. (except when Kerbol is in the way)

Now how do I propose to make a Molniya constellation around Duna you ask? My plan is this:

 

1.  Get 3 long range satelites to Duna and space them 120­° from each other around the planet, 0° inclination. 
2.  Get them to burn to a 60° inclination to Duna while maintaining ~120° separation. (hopefully the burn will be quick.)
3. Have them raise their Apoapsis to 6700km. (half a sidereal day - see vehicle design section to see how the AP is calculated)

Now to complete this task - the Molniya satelites needs a carrier with an antenna strong enough to get signal from Kerbin. If you guessed that this will be the satelite from challenge 2 you are correct.

My crazy idea is to make a Satelite Carrier - deploy it to Duna and put it in an orbit where I can space out the 3 Molniya Satelites in a 100km orbit -  Then perform the 3 steps to deploy them at their correct molniya orbit (Pe: 100km Ap: 6700km) . After this the satelite carrier will deploy the 6 small cube satelites evenly on the 100km orbit - which will provide signal around the equator. Once that is done - we will see how much Δv it has left on the Satelite Carrier and find a good plan for that. 

If this sounds like it's going to be difficult... I agree... This will be a test of my patience and precision.

Resonant Orbit Planning:

Now I thought I would have to sit and actually use my brain to calculate the correct orbit periods etc for launching the satelites to get their space even across the orbit - however I was gifted this great tool that does it for you. Use this to plan the spacing of satelites. 

When I plot in 6 satelites orbiting at 100km I get these ranges: 

The smart thing about planning around 6 satelites LOS is that it resonates with the 3 Molniya satelites - which will be deployed on every second orbit instead of every orbit.

If you - the reader - sees that I have made some terrible error.. please enlighten me 

Now the parameters of the mission has been planned. Now it is all about designing the vehicles.

<<<<<<<<<<Designing the Vehicles>>>>>>>>>>

The CommNet Satelites:

Left: Cube Satelite - Right: Molniya Satelite.

Molniya Satelite: 1064 Δv

Cube Satelite: unknown (25kg of Monopropellant and 2 RCS thrusters. - more than enough Δv)

Now for the communication satelites the Molniya Satelites are the ones that will be most demanding. They will have to burn from a 0° inclination to a 60° inclination - then raise its apoapsis to match ½ a sidereal day... Now.. How to calculate this number was lost on me. Even though I could find the equation online multiple places I could not get google to calculate it propper. So I asked for help on the forum, and help was received. Thanks to @K^2 and others for helping me wrap my head around this. 

To aid others (and myself in the future) I have decided to save the process here:

How to find the AP:

To find the AP for your desired Molniya Orbit you need to first find the Semi major axis of your orbital period - you do that with this equation:

Quote

a = (μ*T²/(2π))^1/3

 

a = Semi Major Axis.
μ= Standard Gravitational Parameter - See KSP Wiki 
T= ½ a Sidereal rotation Period - See KSP Wiki.

If you punch that into google so it looks like this:

Quote

(3.0136321E11m^3/s^2 * (32758.93s)^2 / (2 * pi))^(1/3)

Google is smart enough to understand the values Meter and Second and how they relate to each other.

You should get this number: 3,719.831km - which is the Semi Major Axis for a ½ a Duna Sidereal Rotation Period.

Now this number is the distance between Apoapsis and Periapsis - you may think "but that is an oddly big number" - at least that is what I was thinking. But that was because I "forgot" that there is a planet in between, and that the distance we are shown is taken from the "sea level" of the planet/body. We there for have to subtract the planets diameter. (or radius*2)

Now - I have decided that I want a PE of 100km above Dunas Surface - So to find the AP you have to use this formula:

Quote

 

AP = 2*a - 2*R - PE.

a = Semi-major axis
R = Radius
PE = Periapsis

2 * 3,719.831km - 2 * 320km - 100km

This should give you a distance of 6,699.662km - which I have rounded up to 6700 km  - With 1064 Δv I hope we have enough Δv to finish both maneuvers. (it seems like it should be enough?)

Quote

Note: should your AP be outside the Body's Sphere of Influence you can shorten the Semi-Major Axis by increasing the number of orbits by lowering the Fraction in the formula for the semi major axis:

(3.0136321E11m^3/s^2 * (32758.93s)^2 / (2 * pi))^(1/3) 

By lower the fraction, (Like 1/4, 1/5 etc.) you increase how many orbits the vehicle should take before it is going to be over the same point on the planet again.

This formula is "plug and play" so to speech - you can go to the wiki and lift the numbers, pick your PE and find the AP for any body you want. 

If you want to know more read here:

The Cube Satelite:

If we look at the Resonant Orbit Calculator numbers: See spoiler section bellow:

Spoiler

we can see it only requires 40.4 Δv to lower the AP to 100km - I therefore decided that it would be more cost effective to just give the small satelite 25kg of monopropellant and 2x RCS thrusters to decrease the AP.

This makes the satelite much lighter than if it had actual engines - and I can carry much less fuel - thus making the satelites much lighter.

The Satelite Carrier:

Satelite Carrier with 6 cube satelites and 3 molniya satelites.

Carrier: 2091Δv

The carrier will have 2091 Δv which should be ample since it's going to be launched from LKO: 80km and the Δv map shows it only requires 1690 - 1700 to transit to Duna Low Orbit.

See spoiler section below for reference:

Spoiler

Now - one does not need to look at this monstrosity of a satelite twice to see it wont fit in the small cargo bay for the SDG... So My "promise" to make everything fit within the small cargo bay only lasted until the next challenge... *Teehee*because - of course this was the only excuse I had for a glider re-redesign - It wouldn't be me without it.

The SDGv2:

Left: SDGv2 - Right - SDGv1.

When I first flew the SDG on Challenge 1 - there were 1 obvious thing that struck me. It does not need the docking array. The vehicle is not meant to dock with K.G.01, like the  Multi Fuel Gliders are. So I can do away with that and get more cargo space already - without changing the center of mass and drag a lot.. - how ever.. the satelite is still too long...

But I figured I could add a bit of Tube in the end where the vertical stabilizers are and sort of have the satelite twist itself out of the glider... That being said.. I can easily see things go "wrong" though here... namely:

A theoretical comparison of me getting the satelite out of the cargo bay.

Nothing has ever gone wrong from banging sensitive electronics out of the box... *cough cough* - Luckily Kerbal tech is sturdy tech... 

Here are the two cargo spaces clearly visible - The SDGv1 still loaded with the probe that was send for the Duna Fly By of Challenge 1.

and here a side by side comparison. Luckily the weight savings of ditching the docking port means that even though the Satelite Carrier is pretty heavy at 8.06t - double the payload of its cusin, the Multi Fuel Glider - it only increases weight by 2.22t. Something I am confident that the 1st stage will not have any issues getting into orbit.

Weight distribution across platforms:

Multi Fuel Glider:.............................................................25.34t

SDGv1:................................................................................22.28t

SDGv2:................................................................................27.56t

 

<<<<<<<<<<CONCLUSION>>>>>>>>>>

The plan has been made, Math has been calculated and vehicles designed accordingly. 

Stay tuned in to see if the plan survives first contact with reality.

See you in the next one.

 

 

Edited May 2 by BechMeister
corrected a uneven number of < in conclusion

[BechMeister]

-=MISSION EXECUTION=-
KSP2  and the Three Body Problem.

KSC on a beautiful morning - right before launch.

<<<<<<<<<< Foreword >>>>>>>>>>

It feels a bit weird to keep doing this with what's in the news atm. I feel like mission reports are not that important as of now.. especially not when the games future is in question.. I dont know what I feel and think right now. We will see what happens once the vail is being lifted. The thought of KSP2 having the plug pulled before reaching its full potential sadness me.. I had looked forward to the colony part, and resource gathering.. but most of all the multiplayer.

Any way.. here is the Mission Update that answers if the R&D was well funded.. or a waste of time. I can tell you all the vehicles worked flawless, albeit some tweaks in the future can be made. The title of the blog? - Three Body Problem..? heh lets just say its my terrible humor.. but true too.

More on that bellow:

<<<<<<<<<<MISSION_TASKS>>>>>>>>>>

 

A. Launch Probe into LKO and return SDG to KSC. - Success.

B. Transfer Probe to Duna. - Success.

C. Deploy Molniya Satelites - Success.

D. Deploy Cube Satelites - Success.

 

<<<<<<<<<<Lessons Learned; Lessons Learned>>>>>>>>>>

Goal Post A:

Drone Carrier with CommNetwork being deployed to LKO.

As I expected this step went without issues. One tiny thing was identified though as a possible improvement.Upon stage separation the 1st stage is pushing the SDG, making stage separation difficult. I have decided to experiment with replacing the tubes between the 1st stage and the SDG with the small gitter tubes - I am going to try hot staging to aid the separation. - We'll see next mission how it goes.

Because this step was going to be a walk in the park - I decided to use the step to practice my precise deployment. Although it expended more Δv than if I had just got it into the ballpark orbit, It still had plenty of Δv to get down again.

By adjusting the RSC thrusters down to 1% and the engines to 1% I managed to hit a perfect 90km circular orbit:

The SDG right after 90.000m AP has been achieved, notice that it burned 45° to the Prograde - Not very efficient. HUD cropped into top corner: The achieved 90.000m x 90.000m orbit.

One thing that the practice run(to achieve a precise orbit) showed, was the importance of having an engine with the appropriate power. if 1% thrust is not low enough for fine maneuvering - I would consider putting a weaker engine on.. or make sure the RCS is propper balanced - The glider has 3 thrusters for reverse and 2 for front - which actually was too much power even at 1 percent. Actually I would like to have sub 1% to work with.

The deployment of the probe was possible - even without using the time warp hack:

The SDG deploying the probe.

When I performed the stage separation I could wiggle it 45° degrees - It was kind of stuck from there.. but by using the RCS thrusters on 10% I was able to slowly fly it out - The decoupler, which was supposed to be staying inside the glider broke off though and was left as space trash. Also I never checked to see if the engine clipped through the back of the glider.. but hey.. the probe got out.

That being said I did encounter an annoying bug - When ever I timewarped with SAS set to Prograde/Retrograde - Radial in/out or Target. The probe would bend out of shape:

Quote

I will attach a bug report here once approved - With the current situation with Intercept Games, I assumed bug hunting effort is on hold until further notice? So I have not bothered reporting the bug yet- Normally I wait for my bug reports to be approved before posting the blog... but I wanted the update out now

Any way - the counter to the bug is to make sure you have locked your orientation, or are pointed towards something that does not move while in time warp (Like a maneuver node)

Before we move on to Goal Post B - Of course the SDG and 1st stage was safely returned back to KSC.

See spoiler section below for detailed walkthrough of the Mission Step:

Spoiler

The SDG blasting off the pad. It was a beautiful morning with light cloud cover. The volumetric clouds just looks awesome... SO.. I may have taken an excess amount of screenshots.

I really think the way the clouds simulate light is impressive.

right before engine cut.

Engine cut - flip and burn back maneuver.

flip and coasting before engine reignition. 

Controlled deacceleration. As mentioned previously - the engine plate will not survive speeds exceeding 700 m/s

aiming the rocket for the pad.

breaking the fall.

touchdown.

Back in space.

the glider pushing the AP to 90km

engine cut - the chrome just look so good.

Opening the cargo bay doors:

There it is in all its glory.

Probe deployed and the glider is ready for the back burn. 

Deorbiting the glider.

The glider did not have as much Δv for the deorbit maneuver as usual because I had been practicing the precise maneuvering. Fortunately the glide distance can easily be altered by banking left and right. - here the glider is starting to cut a blazing trail, still 50km up.

I never get tired of watching the gliders de-orbit.

Here adjusting the last range of the glide before continuing leveled flight at 40° AoA

bleeding of the final velocity - the blue and orange has always looked amazing together - notice that the bodyflap is not deployed at this moment.

the glider has entered the atmosphere - even though the glide distance had been shortened with the left right left banks - it still managed to extend the glide again while in "leveled flight"

It was nothing a steep spiral down couldn't remedy.

here the glider is "spiraling down" - in reality it's as close as a controlled dive you can get.

one of the last twist of the spirals before the glider is enough down to level the flight. - I am doing my best to conserve energy for the final flare.

lining up the runway and enjoying the look of the clouds and the chrome mirroring the blue sky.

coming through. still very high, its a good thing the runway is so long.

final flare up before touch down.

and now just coasting to the VAB.

and parked outside the VAB

Goal Post B: The Three Body Problem

Probe Carrier in LKO - getting the final telemetry from KSC before performing the 1st og 3 maneuvers that will bring it to a DLO

This step was almost breaking me and the Mission. I kept trying make plans that got me directly from a Low Kerbin Orbit to a Low Duna Orbit. But even if I did it with all the artistry in the world: Not just burning prograde, making sure Duna was in its ideal transfer window etc.(as well as you can when you need to use a protractor on the screen) I was plagued by issues.  

The vehicle kept not following the path the maneuver node said it would, It needed to have huge adjustments made once out of Kerbin SOI and I kept arriving at Duna with less than 100-200Δ after the break burn to get into orbit. Which was never enough to finish the mission.

After 2 tries I was about to throw the towel in ring when I remembered that getting vehicles back from The Mun to K.G.01 was never feasibly to go directly from The Mun. It was always more cost effective to burn out of The Mun SOI and then do the fine tuning in Kerbin SOI.

It seems to me that KSP2, as of now, can only really handle a maneuver made within the SOI your already in? - if you your maneuver crosses more than one.. you will have a very hard time getting the path right... And my maneuver was bridging three SOI.. or three bodies: Kerbin SOI, Kerbol SOI and Duna SOI.

Once I decided to split the entire transfer into 3:

1. Get the probe out of Kerbin SOI - while in front of Kerbin (so I dont have to burn through the SOI again) and with an AP leaning towards Duna.
2. Make a maneuver within Kerbol SOI that, as efficiently as possible, would intercept Duna at ~0 inclination (its hard to judge as you only get the numbers once in the bodies SOI) and with a PE of ~100km (the further you are from the object you want to intercept, the cheaper adjustments are.)
3. Once in Duna SOI, perform break burn and target 109.916km AP.

See spoiler section below for detailed walkthrough of maneuvers: but be warned, it's a bit of a mess

Spoiler

Direct Transfer from LKO to Duna.

First maneuver node with direct transfer to Duna.

Notice how much Δv the maneuver node said it would use - in the end the maneuver ended up taking a ~100 more Δv to complete, and there were a huge discrepancy between the path I ended with and the path the node said i would end with. 

In the end the transfer burn to Duna would spend 1313 Δv. And even though I would have less Δv on my 3 split maneuver - for some reason less Δv got me further. Even with 778 Δv - I could only just break to orbit Duna - and not even close to the desired orbits.

Maneuver from LKO to Duna split in 3:

First Maneuver to leave Kerbin SOI. - Notice I try to be more efficient with my burn by making sure I cross my Prograde ~½ way through the burn.

After end burn - notice the discrepancy between the maneuver node and the actual maneuver.

I made the second maneuver for the Duna Transfer by pulling on the prograde until the path crossed Duna's orbit - then I moved the node on my orbit until I had a good intercept. Notice how much further from the optimal transfer window I had to be to get a "cheap" maneuver.

I ended up with this path after end maneuver and 558 Δv -interestingly I had less Δv left compared to the single maneuver + correction. But there is a huge speed difference. The final adjustment was made with RCS thrusters.

Once inside Duna SOI i performed the last burn:

Notice that the screenshot was taken mid-burn.

I ended up around Duna with 157Δv to adjust the orbit to a perfect 100km PE - 190.916m AP

Looking at the screenshots now - I do not understand why I could perform the complete maneuver this way - when it seems I had 220 Δv more from the direct burn - but then I had trouble breaking and staying within Duna. I dont know if the velocity is the coulprit. In the 1 maneuver way, my exit speed ot Kerbin was 10245,3 m/s vs 9543,4 m/s = 701,9 m/s in difference.  Maybe in the end, it was just because doing it in 3 burns, meant I could be more precise with my PE arriving at Duna? Meaning I would need to do less maneuvers within Duna SOI?

Maybe someone with a lot of experience in KSP can tell me what I do wrong.. if not - I guess the further missions to Duna will tell me.

After 2 tries at a direct Transfer to Duna - I cut the transfer burn into 2 and finally arrived with enough Δv to continue the mission.

Drone Carrier leaving Kerbin.

Drone Carrier arriving at Duna.

correct resonant orbit achieved to deploy CommSat Network.

I arrived at Duna with  157Δv to adjust the orbit to a perfect 100km PE - 190.916m AP 

To see a detailed walkthrough of the mission step - see spoiler section bellow:

Spoiler

Carrier performing burn to leave Kerbin SOI

Drone Carrier performing second burn (outside of Kerbin SOI) to intercept Duna.

Breaking burn to orbit Duna.

here we see the probe burning at 1% to precisely tune the orbit for deploying the satelites.

Goal Post C:

First Molniya Drone burning away from the mothership to its 100km flat orbit.

Getting the molniya satelites into their orbits did not pose as a significant issue as I had feared going into the project, and all in all the theory worked in "real life". I have split this into a section surrounding each phase of the deployment. 

Phase 1: space the satelites 120° apart.

My biggest issue here was that the 48-7S "Spark" engines were too powerful for the task. Something that would not cause Issues in phase 1 and 2 - but later in phase 3 meant a lot of back and forth burning.

I ended up using Ike to find ~0° inclination to Duna - I really think KSP should have tools vanilla to give you the inclinations to the body you orbit. Any way - the drone carrier set to 1% engine power was really easy to control the orbit, and making sure the satelites were evenly spaced.

all 3 Molniya satelites deployed at ~120° apart. 100km flat orbit.

 

 See slideshow bellow:

Spoiler

1st Molniya satelite deployed.

Second molniya satelite breaking away from the carrier. - no pictures of the third.

Once the carrier had completed all deployments and arrived back at the Molniya Satelite 01 - this was the margin of error between them.

Phase 2: burn to a 60° inclination

Inclination burned.

I tried to get all 3 satelites to burn to their 60° inclination at the same time, by using pause etc. However the game would not allow it.

instead I had to burn one satelite at the time, meaning that they were probably not a perfect 120° degree separation between them. But it still look close enough to me. - the inclination burn shifted the orbit away from a perfect 100x100km orbit - but since all the satelites were pretty much still timed, I figured it would be easier to deal with in Phase 3.

Phased 3: Burn the satelites to their AP of 6700km

first satelite in its correct orbit.

I was quite nervous about this part - the whole point of the Molniya Orbit is that at least 1 satelite will be over the pole at All times, and moving slow enough that a simple antenna can track it. There were a few factors that would make it difficult, and a few unknowns that you can probably solve with math - but that I decided to just eyeball.

Getting into the correct orbit.

One of the factors that made it difficult was the in ability to mark the most southern part of the orbit. Which meant I had to eyeball when to burn prograde to raise the AP to the North. Fortunately the engines were easy enough to get the AP to 6700km - the problems arose once at AP. 

At AP I had to correct the wrong PE to a perfect 100km. The problem was that the engines even at 1% were too powerful - I kept flipping the satelite, burning prograde then retrograde trying to hit 100.000m flat. but instead jumping between 99.998 and 100.002m - In the end I got them all down to the correct orbit. 

A lessons learned lessons identified for the future is either to downgrade the engine power, or give the satelite a little bit of RCS (assuming the RCS at 1% is less powerful than the Spark engine - something that I've come to doubt)

Timing:

I was not sure how to time the satelites propper - and looking back with hindsight. I probably started out with something that would work better with a 4 ship orbit, rather than a 3.

How I solved the timing was by burning Molniya satelite 01 to its 6700km AP. while the Molniya Satelite 01 was at AP. I burned Molniya Satelite 02 to its AP. This meant I now had 2 satelites that would be at each their end of the orbit at all times. After that I figured that if i burned Molniya Satelite 03 to its 6700km AP while 01 was on its way down, and 02 on its way up - to cover the gab that would come between them.

In the future I think it is better to:

1. Burn Molniya Satelite 01 into its 6700km orbit. 
2. When that sat is on its way down (2/3) of the way in its orbit - burn the Molniya Satelite 02 to its AP
3. Once Molniya Satelite 02 is 2/3 done with its orbit. Burn Molniya Satelite 03.

I dont know if this will be a better approach. But looking at orbits speed up:

Molniya Orbit in action.

It looks like the timing is slightly off? all 3 satelites stays up together at one point in the orbit, and then just barely having 1 satelite over the poles another point of the orbit - I think with a 4th sat this orbital constilation would have been "perfect'er". (I guess 1/4th is always easier to guesstimate than 1/3)
 

Goal Post C:

The RCS thrusters on these cube satelites gave a lot of trouble - they were way to overpowered even with 1% thrust. I could not, for the love of god, get them to a 100x100km orbit. They kept dancing between 99.999m and 100.002m just flipping numbers. In the end I gave up getting them into a perfect 100x100 orbit and decided that they had enough monopropellant to correct orbits for a long while.

I tried to allow the satelite constellation to run for 3 more years without guidance, just to see the drift. Only 1 out of 6 cube satelites had drifted in its orbit.. and after docking and undocking K.G.01 a lot - I know exactly how to correct orbits for drifted satelites.

Asume a orbit either a few km higher or lower than the target orbit (slow down - speed up). once you're right above/below your target orbit.. rendezvous with your it by lowering your orbit again.

Example of almost hitting 100x100km flat - and having to give up.

After "successfully" deploying all 6 cube satelites in their orbit. I decided to burn the carrier into a ~200x200km orbit, to make sure it was out of the way. The satelite still have 264Δv left - I wonder if there is any better use I can make of it now. Either I include it somehow to the constellation - or I deorbit it.

Cube satelite constellation in action.

for slide show see spoiler section bellow:
 

Spoiler

first CubeSat being launched.

Second CubeSat being launched.

4th CubeSat being launched. 

Final CubeSat being launched - making the probe carrier seem awful disproportionate 

 

<<<<<<<<<< Moving Forward >>>>>>>>>>

Challenge 2 and 3 complete - and even with flying colours if you ask me.

I always wanted to establish a CommSat Network - now I finally got around to do it

before going on to Challenge 4 - Does anyone have any good ideas of how to use the Drone Carrier? It has 264 Δv left. So its very limited what kind of orbits it can achieve. But if any one have any suggestions on how to better utilize it, I am all ears.

Stay Tuned in for More! Next up - R&D for Challenge 4.

[BechMeister]

-=R&D_UPDATE=-
Tiny Lander

Good day! Here we are again, soldiering on while pretending everything is fine...

I guess it's all one can do at this point... I think I've come to the conclusion that if this was really the end of KSP2. I'll play the content that is there, and then take what I've learned and go my way into the ether.  Any way, todays post will be short.

After successfully establishing the CommNetwork around Duna. It is now time to go dig in the ground and figure out what the soil has to offer. The challenge is as follows: 

  

On 2/28/2023 at 9:15 PM, OJT said:

4. First Landing

Launch an Unmanned Lander (like Viking) and land it intact on Duna. Lander must have an antenna that can reach the Relay satellites, means to generate electricity and some sort of landing legs. Whether you choose to use already provided lander legs or make some of your own from structural parts is up to you

when I initially started to make builds for this challenge I thought it was going to be a walk in the park. But I was surprised how big even the small parts actually are. Also even though the the challenge does not ask for science parts - it just felt wrong to launch a lander that could not take samples from the ground. I mean, the Viking Probe mentioned as an inspiration has means to dig in the dirt:

Painting of the Viking Lander taking samples on the Martian Surface.

So science parts had to be there, now that they are here!

Designing a Lander:

Lander being tested on the Runway of KSC.

It is not easy to build this small. I knew my glider would only take vehicles that were - at maximum, somewhere between Small and Medium. medium would already be too big.. since the vehicle would not be able to leave the bay. So I had to build it out of the Extra Small parts:

Lander from the "front" and bellow.

The lander is basically constructed by taking a M-Beam 650, flanked by XS reaction wheels and strapping on 4 TMP-XS (the tiny 6 way connector) where I could add the 4 LV-1 "Ant's".  Giving the vehicle a total of 70 Δv. (the fuel tank is mostly left empty) The engines also doubles as landing legs.. Since even the smallest leg were huge on this thing.

The biggest issue were fitting the sample arm, (which is rather big actually) and not having it clip into the drogue chute. 

I added 2 solar panels and a z-400 battery - together with the tiny probe core it gives the vehicle EC of 405U. Lastly I added a ASCM-B "Little Sniffer" just because it looks like there is a camera on it.

Considering how much the cameras on the rovers give them personality.. I think its weird that we don't have a rover part with camera etc. on it. 

The lander totalled at .79t with fuel and .77t dry.

Now we just need to get it to Duna!

Duna Lander Transfer Stage:

From Bottom up: 1. Duna Transfer Stage 2. Duna reentry stage 3. lander.

So.. The lander is a little bit wider than the Small heat shield - I figured I could put in a faring that has a cone shape and put a small heatshield at the end. Hopefully the conical shape of the faring will mean that it takes less heat on the way down? and the heatshield will take the brunt of it.

The lander is connected via a decoupler on its side to it. Which is fitting any way since my plan is to get my PE just barely over the surface of the planet - to bleed of as much speed while flying horizontal - so I don't just Pancake into the ground (if the atmosphere is weaker than I expect). So it will be pointing in the correct orientation when deploying. 

The Transfer stage has 1967 Δv which should be enough to get a "impact" path to Duna - it is going to be quite interesting how much the atmosphere does? because even when sending missions to mars in real life we use heatshields right?

The Staging Plan is as follows:

1. Once the lander enters the atmosphere, stage separate the Transfer Stage from the Re-entry stage, and point the heatshield prograde. - The transfer stage will burn up.

2. Once the lander has bleed off enough speed to not rip the lander a part or melt it - drop the faring.

3. Engage the drogue shoot - to ensure the lander separates from the heatshield -  and stage separate the heatshield off.

4. gently touch down with the aid of engines.

The vehicle comes in at (with the lander attached to it) 4.30t total - meaning almost half as light as the CommNetwork Probe launched previously. So getting it into LKO should be a walk in the park.

Speaking of getting into LKO: 

Hot Staging:

To help the SDG separate from the 1st stage - I have tried to use 3x CT-S-1 instead of the 3x SF-125 as it looks closer to something that could enable hot staging - I don't know if the game will register it like that? or if the part will survive the heat - We'll see.. if they burn off I guess it does not matter much anyway. As long as the SDG flies clean off upon stage separation.

SDG with the Duna Lander vehicle attached in the cargo bay

<<<<<<<<<< Moving Forward >>>>>>>>>>

Next up is launch - Which I think I'll get done pretty quick. We'll see if the little thing does well - I guess with a lander like this, making sure you land on a flat surface is also alpha omega.

Any way - see you in the next update.

[BechMeister]

-=MISSION EXECUTION=-

The transfer stage bleeding off energy before deploying near the polar cap of Duna.

<<<<<<<<<<FOREWORD>>>>>>>>>>

I have decided that, even in the event that this is the end of KSP2(we dont know yet). I'll still continue to grind the content I can out of this game. I am at least aware of the most prolific bugs now, and know how to design around them... and I have only just left Kerbin.. There is so much more to get out of this sandbox still... The KSP2 engagement seem to be on the low end though.. and while I do enjoy making these long detailed blog posts about my progress. Not knowing if any one reads them, is killing my motivation to write them.

I will be finishing the Duna Mastery Challenge though! But I had planned to do the same rundown on Eve next.. But we'll see if that will be something I'll write about. I think that depends on what level the engagement with the game is like, at that point.

Any way.. This challenge went alright.. I must admit though that I was surprised with how thin Duna's atmosphere actually is (even though I knew it was). More on that bellow:

<<<<<<<<<<MISSION_TASKS>>>>>>>>>>

 

A. Launch probe into LKO and return 1st stage and SDG to KSC - Success

B. Perform Transfer Maneuver to Duna - Success

C. Land the Lander near the Polar Regions - Success.

 

<<<<<<<<<<Lessons Learned; Lessons Identified>>>>>>>>>>

Goal Post A:

The SDG launching the Probe into LKO.

This leg was pretty much business as usual - Although I did learn that the SF-125 will be burned up by the exhaust from the 3x Lv-909 "terrier's" - That did not bother me too much. It looks a lot better to see the exhaust plumes to "clip" through an part that is open, rather than clip through a closed cylinder.

where as it feel redundant to wish for something to be added to the game in these times... I still wish we could hot stage rings in the game.  

The launch went without incident and the probe was successfully deployed (being a lot shorter made it very easy, it flew out of the cargo bay on its own RCS power.

For detailed walkthrough of the launch See spoler section bellow:

Spoiler

Lift off! I kind of wish that the tower parts we use to hold the rockets.. were actual attachement points to the launch towers.

Blasting off into space.

Clean stage separation - 1/3 SF-125 burned away. - the other two would fall off.

burn back to KSC.

As you can see the two surviving SF-125 broke off on the way down - but I always liked the look of the 3 split piece without the extenders.

Lining up the pad.

And touch down - all routine now.

the glider is burning itself into an ~90.000m x 90.000m orbit. - I am not being precise this time.

close to the point of the reentry burn the cargo bay door slides open to reveal the probe to the vacuum of space.

Probe is deployed and the SDG is creating distance, as to not fry the satelite with its exhaust.

The probe is ready! Now it's time to land the glider. The fact that I did not try to be precise with hitting 90.000m x 90.000m, and that it was half the weight of the CommNet carrier, meant that the glider had ample of fuel for its deorbit burn.

The longer deorbit burn meant for a gentle reentry - the flames never got bigger than this.

I still managed to overshoot the runway, and had to do a hard break. before spiraling down:

by following the 45° angle from straight down, I made a really narrow spiral dive. Getting down quickly, while maintaining airspeed. It's kind of crazy that its terminal velocity is not much higher than 148,9 m/s

It lead us to come up perfect to the runway.

and touch down. 

 Goal Post B: 

Duna Lander Probe - making transfer burn to Duna.

Because I had the CommNet around Duna now, I decided to just put on a small antenna on the vehicle - with a range of 200 Mm. I figured the vehicle would only need trajectory when leaving Kerbin and approaching Duna... How ever I was surprised of how "short" 200Mm was in reality - not extending that far away from the Kerbin SOI. It meant I had to do a little quick load.. you see I had decided to do the approach of burning out of the Kerbin SOI, then make the maneuver for Duna at a optimal point. 

However - The optimal point was way outside CommNet range. So I decided to do a more expensive burn and then just make sure that the Duna PE would be a few KM above the surface. I would not have Δv enough to circularize around Duna.. but I didn't need to since I could just be Aerobraking.

the maneuver that got the Lander Probe to Duna.

The most important thing for me would be to bring the probe  over the North Pole - Final adjustment would be made once in the Duna SOI. - The probe was allowed to coast all the way to the Duna SOI without any signal - a bit harrowing... For a sec I thought that the CommNet wasn't able to relay signal.. but it was just because the signal was only reaquired after the timewarp stopped.

The probe had successfully arrived at Duna SOI

Goal Post C: 

Lander safely on the ground, taking its first sample.

 

Once inside the Duna SOI it showed that my my path would take me directly through Ike's SOI - which made aiming quite difficult actually - since Ike naturally gave me a high ark to Duna. 

The probe zipping past Ike on its way to Duna.

Fortunately there were plenty Δv left to push the PE down once I was through Ike's SOI. For RPG reasons I was interested in testing the soil near the poles of Duna - Seeing the canyons between the poles I figured that would be a cool landing site - so I aimed for this place:

After finding a point to aim at I, then raised the PE to 4km above surface - to make sure that the vehicle didn't pancake into the ground, if the atmosphere wouldn't break me as much as I hoped it would...

The last Δv was spend aiming the trajectory for the canyon - or general area.

The transfer stage being ditched - and the landing stage burning through the atmosphere.

once the atmosphere started to heat up, the transfer stage was dropped and the lander stage just flew through the atmosphere like a bullet. It bled of the energy.. albeit much slower than I anticipated - the lander would drift quite far before the speeds were dropped to a level were I felt comfortable the lander would not have been torn apart (at least in our world - In the world of Kerbals they have the alloy Kerbalium . And that is most sturdy) the fairing was dropped, and the scute deployed soon after.

lander drops fairing - creating a lot more drag.

After that it was just a question of dropping the heat shield - I dont know if its a bug? or if Duna's atmosphere is just so light it does not need heatshields...  At least it had not spend any of its ablative propperties . 

The scute was deployed and the 4 engines put it gentle down to the ground.

The lander breaking for a gentle touch down.

The lander would touch down a generally flat place, on the other side of the ice sheet I was aiming fore.. but at least in one piece. We are still taking a sample of the Duna Polar Soil, which can lay the foundation to find the ideal place for future manned Duna Missions.

The probes final resting place.

The battery power is a bit light - the lander goes all the way down to EC 70U before sunrise. If all unnecessary power usage has been eliminated. Of course the lander could go into hibernation mode in the night.. but I dont know if that is considered "cheating" in relation to the goal post stating that the vehicle should "have means to generate electricity" - I guess it has the means in the daylight.. but If we go by the Martian Landers and Rovers of our world.. power is spend in the cold nights, making sure mission critical hardware is not killed by the cold. I guess that is of OJT to judge.. where ever he is now days.

For picture slide show - see bellow:

Spoiler

The lander after having performed a Anti- Normal burn to adjust for planet rotation.

Saying goodbye to the transfer stage - here the lack off effect on the heatshield is clearly visible. 

the big canyon with the two white peaks in were the spot that I aimed for.

here flying over it - still in high speeds.

the last glow desapating. stage separation would happen just as the hot plasma would extinguish.

The protective faring separating from the craft.

Dropping the heat shield (no longer needed, and deploying the Drogue Chute - to ensure propper stage separation.

Drogue chute doing its thing.

As the sun sets the vehicle is closing in on the ground.

Touchdown!

The craft gets the last bit of sunlight be fore hanging in tight for the night.

The next day it was ready to do science.

<<<<<<<<<< MOVING FORWARD >>>>>>>>>>

with that being a - Challenge Success! - it is time to move forward.

Since the parameters of the next challenge is pretty much the same - at least if I just put wheels on the lander. I have decided to compile the R&D post for Challenge 5 and 6. Otherwise the R&D post for challenge 5 will be very short. Since I will mostly be able to use the same vehicles.

See you in the next one! 

Edited Thursday at 07:04 AM by BechMeister

[BechMeister]

-=R&D_UPDATE=-
Rovers and Mars Sample Return Mission:

So I just went through a lot of convoluted R&D to complete Challenge 6 - just to realize that I read the challenge wrong when I read it. I thought the requirement was to get a rover back and forth from Duna - Not a Lander.. (which does make the mission a lot simpler). I think that I, in my head, focused too much on perseverance as being part of NASA and ESAs real Mars Sample Return mission - without realizing that challenge 5 "is" the perseverance mission - that I build both challenges into 1.

Needless to say - Now I've build it - with 12 stages and all... to get it there and back again... So I'm going to do it! 

The challenges are as follows:  

On 2/28/2023 at 9:15 PM, OJT said:

5. Desolation Road

Design an Unmanned Rover, send it to Duna and demonstrate its functionality by covering some distance in it. Rover must have an antenna that can reach the Relay satellites, means to generate electricity and at least 3 wheels

6. Bring It Home

Design an Unmanned Lander that can land on Duna and then subsequently return it intact to Kerbin. If the Lander is multi-stage, the stage with Probe Core must be returned. Otherwise the requirements are the same as in Challenge 4

 

Challenge 5 Rover:

Updated Lander making a survey test near the Runway 1

Since the rover was going to be mobile. It made sense to replace the solar panels with a "Multi-Mission Radioisotope Thermoelectric Generator"(MMRTG) (NASA sure like their acronyms). In game it is known as the PB-NUK power plant.

Instead of a tiny drogue chute I gave it small MK16-r parachute - The drogue chute was almost enough to land the lander. So I hope that the small parachute will do and I can skip the engines... as I had trouble figuring out how to give it fuel and place rockets on it.

Challenge 6 rover and Sample Return Vehicle:

Since the challenge 6 required a vehicle that was big enough to get to Duna and back again, I knew it would not be able to launch it from the SDG. It gave an opportunity to develop a new and bigger rover. I wanted to cram as much science out of the vehicle as possible - and one of the most challenging things to get on it would be a WSRL-01 radiation survey. Which seems like a good thing to survey before a manned mission x) 

Now making the rover was not going to be the hard part... Making a vehicle that could deploy and retract a rover would be. The fact we dont have any crane parts meant that the rover had to somehow be able to drive in and out of the lander vehicle... or the vehicle would have to be able to lower a port that allowed it to dock to it again.

It took 2 attempts to develop such a vehicle:

Attempt 1:

a test of the vehicle on Runway 1 - notice the landing legs is placed to give stability and prevent the vehicle from falling on uneven surfaces.

The idea behind prototype 1 was that rover could drive in and out the bottom of the decent and accent stage. It would put a limit on the size of the rover - but the medium size would still be more than enough room for a rover with all the science equipment.

The Accent and decent stage looked like this broken up in its parts:

 

 

 

From bottom up:

1. Duna Decent Heat Shield - with deorbit engines.
2. Rover Carrier and Kerbin decent stage
3. Service Stage for Duna Kerbin transfer.

The landing procedure would be this: The Duna Sample Return Vehicle (DSRV) would decouple from the Kerbin-Duna Tour Retour Stage (KDTRS) and the tiny fuel load on the heat shield would deorbit the lander.  Once through the thick of the atmosphere the heat shield would be dropped to save weight. and the stage would land via engines and chutes.

Then the rover would drive out and do science, once ready it would redock with the lander and ascent again. Once into the vacuum the farrings would be blown off and the docking port would be ready to dock back with the KDTRS.

When back at Kerbin, the DSRV would then decouple from the KDTRS - again - and deorbit. Once de-accelerated (no more flames) it would also drop the heat shield and deploy a second pair of parachutes for a soft touch down..

However - theory and reality did not align. Once I had made sure the vehicle could land itself I was going to test if the Rover could drive back in. The fact that the engine plate is as tall as it is made me worry that it would not be able to drive over the step. I tried to replace the engine plate with other flat medium sized parts - but in the end it would be just as tall because of the engines.

Radially deploying the engines were not an option - since having the exhaust next to a surface drastically reduces thrust - and It was not possible to place them Infront of the doors (aesthetically it felt wrong to me.. if movable things clip through things it feel like cheating) 

My worry was well funded - but not only that I couldn't drive back in - For some reason the rover couldn't even drive off the engine plate.

Left: even if the engine plate did not have landing legs or engines the rover could not get in again.

Right: It's a bit hard to see  - but the wheels are just spinning.

Another way to make the vehicle had to be done. I remembered how I made my dropships for Minmus. And I decided to do something similar - see spoiler section for reference If you have not read my Overengineered Minmus Mission:

Spoiler

On 2/10/2024 at 8:59 PM, BechMeister said:

B. Designing a Dropship:

Attempt Two:

I decided to make a stage that would lie flat on the ground, and then by adjusting how much the cargo bay doors open, I could adjust the angle of the docking port - and by breaking and accelerating the rover. Or increasing spring strength on the front wheels and reduce on there rear wheels, I could make the rover pitch up and "catch" the docking port. I made a small mock up as a prof of concept: 

For a more thorough test of the landing of the proof of concept.See spoiler section:

Spoiler

Next was finding the way to get it back into space again. I developed a 2 stage system. A 1st stage with 1320Δv, just shy of being capable getting into DLO - and then add a little bit a fuel and 4x LV-1R "Spiders" to the "Proof of concept" 2nd stage giving it 357Δv. Which should be enough, and then some, to give it the last kick into orbit and rendezvousing with the KDTRS. 

Left Top: 2nd stage - Left Bellow: 1st stage - Right: the Duna Lander Module.

Next up was making a way to get it through the Duna Atmosphere. Now - since the Heat shield on challenge 4 did not take any damage - I decided to try do away with it on this build. Instead I build an aerodynamic faring and applied grid fins to help steer it down. The Duna reentry "vehicle" could then have a heat weak medium docking port as its "decoupler" - meaning that there is cohesion with the 2nd stage when it returns to the KDTRS.

The reentry vehicle is pretty simple. Its purpose is to just shield the vehicle from being scorched by the plasma, then blow off and allow the sample return vehicle to land.

It looks like this:

Launch Vehicle and KDTRS:

Last thing to do was to develop the vehicle that would bring this monster from LKO to Duna and back again. The easiest thing to do was to look at something I had build before and already flown a lot. I took the 1st stage for my Heavy Refuel Vehicle to K.G.01 (my space fuel station in LKO) as seen here:  

On 12/20/2023 at 9:43 AM, BechMeister said:

The final version, and fully certified H.T.V. - 2nd stage and 1st stage.

The 1st stage is designed to push. The Tanker Vehicle of 119.62t to ~900 m/s or 25-30km - before returning and landing at KSC again. So it has not trouble pushing the KDTRS + DSRV at only 79.08t into LKO if the stage is wasted.

Final design of 1st stage and KDTRS

The KDTRS has a total of ~3.439Δv after giving itself a tiny boost into LKO. That should theoretically be enough... When going to Duna I tend to use shy of ~2000Δv - the DSRV weighs  13.21t going to Duna - and less than 4.76t when it returns (depending on the fuel level upon docking). So I hope that 1.439 Δv will be ~2000 Δv. I could do the rocket equation.. But my gutfeel says it will be enough to go there and back again. 

If not I guess we will have a rescue mission to launch.

 

<<<<<<<<<< Moving Forward >>>>>>>>>>

I expect the launch Challenge 5 tomorrow - and then write the update Sunday? (we'll see how it goes - plans only last until contact with the enemy after all)

Stay Tuned - Until next post!

Edited Friday at 08:32 PM by BechMeister
My son decided to be my editor.. and that I was a too slow writer and hit publish. Fortunately I am his father - So I overruled him and finished the rest in post.

[BechMeister]

-=MISSION EXECUTION=-
Murphy Strikes

The rover being launched into LKO.

<<<<<<<<<< FOREWORD >>>>>>>>>>

So! That was an odd launch - Everything went wrong - but not so wrong that the next leg of the mission couldn't proceed. Until the lander touched the Duna surface that is. I decided to just roll with it.. but in the end it became kind of comical how this update would only have a single suffesful task - namely getting the probe to Duna 

Any way, I learned something with every failure. - More on that bellow:

<<<<<<<<<< MISSION_TASKS >>>>>>>>>>

 

A. Deploy the probe with the SDG and return the SDG system to KSC. - Failure

B. Perform transfer burn of the Rover Probe to Duna - Success

C. Land rover on the surface of Duna - Failure.

 

<<<<<<<<<< Lessons Learned; Lessons Identified >>>>>>>>

Goal post A:

1st stage collapsed on the landing pad.

I dont know if i jinxed myself last mission post - by writing business as usual. Because even if I tried to get the landing to stick twice I failed twice. I decided to just roll with it... Even spaceX still tumbles a rocket every once and a while.

I am still not sure why I had such a hard time landing it - I had more Δv than I usually have. Maybe it made me more slobby? or maybe the weight of the rocket was the issue? In any case, on the 1st attempt I had lateral movement over the pad. Which meant that the rocket tumbled on the landing. I always try to come into the pad on an ark. I find that it is easier to kill lateral movement by coming on on an ark and slowly controlling the decent by burning retrograde until the lander is pointing straight up - with no lateral movement - and then controlling the de-acceleration for a soft touch down. I find if I, on the decent phase, fall "straight" down I end up getting lateral movement when doing the fine aiming for the pad.

On the second failure a leg broke off on touch down. I had a hard time timing the de-acceleration. I wonder if the extra weight of the excess Δv caused my timing to be off? Any way.. the result was the same. Maybe I should do some testing to see if having too much fuel coming down means the legs can't handle the weight.

Any way - back to the glider:

The SDG deploying the probe.

The glider made it to orbit and deployed the probe. The glider also had an excess of Δv. So I figured deorbiting would be easier than ever. I had overshot the runway the past too launches.. (still making it though) - So I did the decent burn earlier. But too much earlier. - The early burn plus excess Δv meant that It soon became evident that I would not make it to the runway by a longshot.

Finding a good landing spot was "alfa omega" - the glide efficiency is not great on the glider... you really need to time the flare maneuver right to bleed off speed and stick the landing. Too soon and you will pankage into the runway, too late and you will not be able to keep the nose pointing upwards, and the vehicle will break in two- and thats on a completely flat surface. Which meant that I could probably not land uphill.

I found a nice even looking patch of land and managed to land the vehicle on a small hill, devoid of trees (almost)

The glider touching down - notice the sharp angle the trails are taking - it was not a soft landing.

Lessons Learned: The glider can make an emergency landing if the landing site is carefully chosen.

For detailed walkthrough of the mission leg - see spoiler section:

Spoiler

the rocket blasting off.

Stage separation - I found that I burned my monopropellant tanks on hot staging - So I have moved them further down. Before they were situated right below the 3 split plate.

Returning to KSC.

aiming for the pad.

breaking through the thick clouds (made it hard to aim) - a Hud element you could toggle on/off that shows the pads and landing strip in the dark or heavy clouds would be nice.

a leg broke on the landing, and when it tumbled it rolled off all the grid fins and broke the top off.

back in space:

The glider finish its orbital insertion burn.

probe deployed.

performing deorbit burn over the southern cost of the western desert

controlling the decent. Since I was sure I was not going to overshoot this time - I just took a flat 40° AoA.

here from another angle.

Here the airspeed was dropping rapidly - and it was evident that I would never reach KSC.

I decided to break left as it looked rather flat.

I decided to go for this ridge as it looked relatively flat - and easier to land on than in the depressions on either side of it.

landing gear out. losing airspeed rapidly. 

Now it's just hoping that the landing gear holds.

And safely landed.. Now it just have to be picked up.. we're just a tiny bit off.

relativly speaking x)

Goal Post B:

The probe arriving at Duna.

I saw a smart trick on the internet - since the ideal transfer window to Duna is 44,4°. You can take a a piece of paper and fold it so it shows 45° and place that pointing on Kerbol and when Duna and Kerbin is visible from the paper - you have ~45° (which is close to 44,4°): see spoiler section for reference:

Spoiler

When I did this I was surprised how much off I had been - gauging the degree's with my mk.1 eyeball.  Because the image with ideal transfer windows - in degree's, had been simplified (all the orbits have the same distance to each other) - placing Duna in continuation of the position of Kerbin meant I was several degree's off. Its obvious I know.. 

Any way, getting a better transfer window meant that I came to Duna spending much less  Δv: Screenshot for reference

The probe arrived at Duna no problems.

Goal Post C:

the conclusion of this ill fated mission. A rover in pieces on the surface of Duna.

I had two problems coming in to this mission. First problem was that I was going too fast. If I just allowed the heatshield to be pointed forward the probe would just shoot straight through the atmosphere - Even if I spend all my remaining Δv breaking - the capsule would still accelerate to 2000+ m/s before being low enough for the atmosphere to do something. All I could do then was just wave Duna goodbye and have the probe be lost in space until Duna would line up again.. some time in the far far future.

Desperate times means desperate measures - I found that if I flew the probe backwards I would break: 

Duna Lander entering the atmosphere

Depending which way I pointed the probe I could even lower or raise the PE. giving some controllability..

The Second Problem was that the lander was too heavy and hit the ground with ~14 m/s and broke into pieces. 1 parachute was not going to cut it - it need breaking engines.

But two important lessons were made:

1.  Heat shield's are more of a hindrance on Duna - they turn the probe into a bullet and is just weight not spend. I got confirmation that the fairings can take the re-entry heat and will be building re-entry capsules for Duna with farings.
2. Duna's atmosphere is so thin that you cannot rely on parachutes only. Unless you put on a lot of chutes.

for detailed walkthrough of the landing - see spoiler section bellow:

Spoiler

spending the last Δv on breaking before releasing the transfer stage.

The burn lasted well into the atmosphere - the Δv was spend shortly before the engine burned off (lucky) - I then decoupled and as the capsule push away the lighter transfer stage. - now accelerating again.

Here from another angle.

I notice that the capsule is just building speed.

the capsule has flipped to break.

the farings are dropped.

Parachute deployed.

we are breaking.

but not enough

 

<<<<<<<<<< Moving Forward >>>>>>>>>>

Now - this blunder offers an opportunity to give Challenge 5 and 6 a new go. I have looked into the Mars Sample Return mission - that may be launched... And I actually really think its some nifty small vehicles ESA and NASA has planned for it. So I may design an actual lander that can work with a rover - and make a return vehicle with ION engines? They seem a bit gimmicky to me in KSP2 - I guess they are gimmicky in real life too... but their low thrust makes me think they take quite the patience to use. 

We'll see - Except a R&D post next - then I can launch all 3 rockets in the next duna transfer window.

Stay tuned in for more!