Search the Community

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>>>>>>>>> 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: 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: Launch the vehicle. as soon as it is clear of the tower, tilt ~5° eastward and lock prograde 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. Once at 1600 Δv - engine cut. stage separation. orbit the SDG. De-orbit the 1st stage. 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) 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: 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!