MO02/02-Parts design

Table of content

  • 1 Designing the Network relay ( Remote tech)
  • 2 Designing the LEV
  • 3 The Science Rover
  • 4 The Base with life support
  • 5 Assembling parts
  • 6 The Orbiter
  • 7 The Launcher
  • 8 The refueler tanker

1 Designing the Network relay ( Remote tech)

The Communotron HG55 is the best choice in this case, balancing cost, range and electrical consumption. I also add a KR14 for temporary long range operation (to follow a ship or establishing an emergency connexion with Eve)

I usually try to use a geosync network even if it’s not mandatory but it’s not always possible. In this case, with a Synchronous orbit of 18 173.17 km and a Sphere of influence of 9 646 km, the network should be above the sphere of influence of Moho. So it’s not possible. Then, I have chosen an altitude network of 2500km which will give me the higher stable network possible with only 3 relays.

This tool gives me valuable information; night time will be of 2023s and i need to generate 2,677 EC/s. Moho is near the sun and a single large panel array give more than 100Ec/s so it won’t be a problem. I need 5500Ec batteries only for the antennas, So let’s use 7k batteries in total. We will use the others datas when we will deploy the network. Now, we have all the datas we need to design the relays.

Et voila. 3 relays assembled on a tricoupler (position slightly tweaked to avoid collisions) Protip: disable staging for decouplers and set the decoupler force to about 10/100. Otherwise, you could break something when decoupling (not related to events and absolutely not related to my Eve network, where 2 sats were wasted because of that…)

Next step. the LEV.

2 Designing the LEV

The Light Evacuation vehicle is a lander able to go from the orbiting ship to the base and back with 3 kerbals. It need to be light and equipped with a dock. According to this delta velocity map, i need 1km/s to land and 1km/s to get back to orbit. I could design it only for the landing and refuel it with the isru on the base but if anything is broken on the base the isru could be non functional. I also add 500m/s because the base won’t be in equatorial position and because it seems safer. So let’s go for 3km/s minimum.

Tadaa! I used 4 48spark engines to power it. With a Twr of 1,21 (when fully loaded) ascent and landing will be slow. i packed 150 monoprop, which is a lot but i like to be comfortable when i dock. Do not forget the ladder and lights below the ship in case of a night landing. An okto2 is hidden below the docking port so the ship can fly empty. Finally i added 2 hexcans life support (shown below the monoprop tank). Landing and ascent will only last some minutes but … ya know….

The Lev views from below. One 4k batteries is way too much but I play with TAC life support so electricity is mandatory for air circulation. Some tests on the launch pad show us the ladder was misplaced and a kerbal could not use it. He can use the jetpack to go to the pod but with things in pockets (Kis/Kas) it could be difficult, so it’s best to have a functional ladder.

Now, we need a small science rover.

3 The Science Rover

Well, it is not really small…. It weight about 1,5 tons but it packs all science parts i have at this time. It can be manned and has a science container. The Material bay is the reason of its medium size.

Notice the R2 connector (kis/kas part) which will be used to connect the rover to the base. The rover will be delivered attached to the base. At this time, i don’t have a clue of how i’ll assemble all the parts to a unique launcher. I could have used parts from the malemute series (from USI malemute rover mod) but it would have been far too big. I ll bring a malemute later…

Well, Kids, it’s time to design the base itself.

4 The Base with life support

This design is a proven one i already used for Dres. But i need more DV to land on Moho. Hence the stacked fuel tanks.  I have played a lot with skycrane but it’s complicated and tedious to manage. I prefer to use a self landing base with 2 Meerkat engines from Planetary base Inc mod.

The central and main part is the K&k Planetary central hub. It has 4 connexions points, can handle 6 kerbals and comes with a lab, a Carbon extractor and a water purifier. K&K is an acronym for planetary bases inc system. I want to keep a low torque (below 20) for the landing, so here ‘s how i designed the base around the central hub.

I put an engine and a tank below the hub. I won’t use them, it’s just to let Kerbal Engineer Redux give me the torque value. If a ship is perfectly symmetric and lined, the torque should be 0. All others values are irrelevant at this time (dv, mass, twr)

For the demonstration only, if i add a part on one side, the torque will be great and the ship won’t be able to fly in a straight path: it will rotate and will be uncontrollable.

So what is the solution? Well, you ve got it: add the same amount of mass on the opposite side. You now have the idea of the design process.

First i added the batteries and the Life support containers. Then i added two ilfe support converters. The base was clearly heavier on the left side. I then added the Isru and 3 inline drillers. Then i added a small ore container on the right and a rcs tank on the left. Finally, i tweaked the symmetry by changing the amount of rcs on the rcs tank. Now, i have a torque of about 0,3. which is almost perfect and can be compensated easily with the gimbal of the engines and the reaction wheels. Notice the tank and the remote control guidance on top.

I added two beams to handle solar arrays, antennas and radiators. When i ll set up the base, i will move these beams with Kis/Kas on top of the central tower. In this position it is not possible to deploy the radiators, they will collide. I also added two docking ports on the 2 free connexions points of the central hub so it will be easy to upgrade the base. Now, it’s time to attach the engines.  Do not forget to remove the engine below the hub.

Here is the beast. I need two of them, one on each side. (note; i’ll also add two twitch engines on each one to achieve a practical TWR)

A twr of 1,8 is ok, a torque of 2,32 is almost perfect but wait, with 555dv you’ll land nowhere but on Minmus. We have to add some fuel.

Still not enough. Notice the decoupler to remove the tanks when empty. The torque won’t change as i am in symmetric mode.

Aaaannnd it’s a go! with 1933dv i have almost twice what i need but ya know… it’s better in this way… I use sepatrons to remove empty tanks because they are retarded and stay stuck on the central one. In fact, i need only 5 tanks but if i want to keep the torque around 0, i have to use 6 of them. i could also tweak the amount of fuel in each tank but life is too short so fuck this shit. erm, i mean, i prefer to have a reserve amount of fuel. I also added 2 twich engines on the meerkat engine to achieve a twr above 1,3

Last but not the least, i added a rcs thruster on each side. as the ship is symmetric, i don’t need to tweak them.

Now our base is finished, it’s time to assemble the puzzle in a launcher. It will be epic…. At this time i have no idea of how i will do that. But i need about 13kv to go to Moho, so the best thing to do is – i think- to launch everything in lko and refuel here.

HEP HEP HEP SOMETHING WRONG! i haven’t checked the life support and i want 3 kerbals to stay alive for at least 2 years. At this time they will last only 250 days so…

So i just have to add One supplies tank and it’s ok. It has lowered the twr and the Dv but it still enough to land. Another thing which must be taken in account is electricity. with 20k, i won’t be able to drill and convert with the isru during the night, i ll have to upgrade the base with more batteries next time. Anyway i have only a small tank so i won’t need to drill at night. the tank will be filled within a couple of hours.

So now, for real, the compound.

5 Assembling parts

 

Can i put the base in a 3,75 fairing? answer; yes.

To merge ships, you have to reroot the part you want to attach. Use the reroot tool and click on the tricoupler, and save your relays. Then reload your base and merge the relays.

Merge function is available in the load menu.

Attach the relays below the hub. Do not forget to add a separator or you will hate your life. reduce the separator force to a small amount (let’s say 5 to 10)

Now, add the LEV.

Nope it’s a bad idea, i want it below the base to minimise the fairing size (hence the cost and the mass)

Hey silly me! I have almost forgotten the rover, i need to land it WITH the base so i have to retweak the rcs tank on the left to compensate the torque. Luckily, i just have to add more monoprop.

I know why you are laughing but you are wrong; the rover weighs about 1,6 ton, i can move it safely to the ground with kis/kas and only 2 kerbals…

note: i’ll have to slightly move and rotate the rover later to let everything fit in the fairing.

Here is the finished payload. It weighs only 93 tons. It won’t be so complicated to lift it and bring it in orbit. ( a little optimistic for sure….)

But first, i need to do some integrity structure tests.

Surprisingly, it was good, until i deploy the fairing. I encountered some random explosions each time and i have understood something i didn’t know.

Beware when mixing parts from different families. MK3 and 3,75 parts look like they have the same size but it’s highly recommended to use an adapter to fix them together. The structural link is far better with the adapter and no explosions occurred with it.

Additionally, when sides of the fairing collided on the Pad, it happened something you all know. But the test is a success and everybody has survived. Yes it’s true. I swear.

The compound is made of different ships launched at different time. From now the values of the higher stages are irrelevant. I need to block ALL tanks (another solution is to set thrust limiter of all engines to 0) until KER reads 0 everywhere)

 6 The Orbiter

 

It needs strong rcs to dock, a lot of reaction wheels to rotate it, various docking ports, and a crew capacity of 6 kerbals.

Let’s have a look in details.

For obvious reasons, the orbiter will be powered by nuclear engines.

  • With an Isp of 800, nothing can beat the efficiency of this engine.
  • ISP (specific impulses) is a complicated concept beyond the scope of this album but to be simple, Higher is the Isp, farther you can go with the same amount of fuel. But there are numerous drawbacks.
  • This engine is heavy. 3t is way too much for small ships, so it is reserved for big ones.
  • It costs 10k (but the total of our ship will be above 1 million so… who cares)
  • Its thrust is ridiculous, you’ll need a lot of them to push a heavy ship. for the present situation, i ll need 9 of them, so a weight of about 27 tons only for engines.
  • Its thrust is absolutely ridiculous on the atmosphere and can’t be used in such situation. At all.
  • It doesn’t have gimbals so it can’t help to rotate your ship.
  • It is much longer than all others 1,25 engines.

But it only uses fuel, no oxidizer, with dedicated tanks, you can pack a lot more fuel than with conventional tanks on the same volume. And as said before, with an ISP of 800 it is the mandatory choice for interplanetary journeys.

A closer look of the 9 engines.

In the bay, you’ll find 6 big reactions wheels (you’ll see later it’s just enough) some Life support containers and 5 4k batteries. Rcs thrusters were tweaked with Rcsbuild aid mod, an editor mod only. The ship will be launched almost empty, with only enough fuel to rendezvous and dock to the refueling station in LKO. Fully loaded, it has almost 8000dv. But now we have another problem i’ll fix later when the launcher will be designed, the base with the attached rover, lander and relays is not symmetric from this perspective, it will generate a lot of torque and the ship could be incontrollable.

note: 8000dv is not enough: it could be sufficient if i use Eve as a slingshot or if i wait for a specific situation but i can’t wait forever with a manned ship and Tac life support activated. I will attach later another lander in front of the ship to provide the missing DV. At this point of the design, i hadn’t understand this….

As you can see, with the launcher, the torque is above 10% of the thrust. A torque of 1247Knm is gigantic. A lot of reaction wheels and gimbals can handle this but it’s a big waste of energy.

It’s easy to handle this problem, just offset the payload with the move tool until you find the lowest value. In this case, i moved the docking port, but it was not enough, so i also moved the decoupler.

And now, we have another problem… with the offset, the rover doesn’t fit in the fairing which is already at the maximum size… KSP didn’t complain but when i will deploy the fairing, it will brake the wheels and anyway, it’s sound like a cheat for me so i have to manage this situation now.

So i just rotated and moved it. Problem solved.

7 The Launcher

 

We need to build a launcher able to send about 200tons on a low kerbin orbit. It will be big, i’ll use some 5m tank from the Apollo serie (FASA mod)

With 3 5m tank and a Mammouth engine, the TWR is about 0,84 in atmospheric situation; it won’t lift. I need to add some engines.

I added 4 vector engines (these engines were developed for the Us shuttle) Now i have a twr of 1,56. The rocket will lift, but with 1682 dv, i won’t approach an orbit. I need to add more tanks and more engines.

Vector engines have a great capability of vectoring (hence the name…) of 10°. It will help a lot to stabilise and angle the rocket. From ground to a low orbit, i need about 4500dv.

I added 4 huge tanks and a mainsail engine on each one. I can’t show you the full rocket, i don’t have enough zoom on the VAB….

To be precise, i added 2*2 tanks in asparagus. I encourage you to prospect asparagus as it’s a really efficient way to lift a big payload. To be simple, it’s a way to transfer fuel from a tank to another to maximise thrust the maximum of time.

Now we have about 3500dv. I still miss 1000dv. I can’t use the orbiter to finish the circularisation: 1000dv with such a low twr will takes too much time and i’ll get back in atmosphere before.

So? Yeah you are right MOAR BOOSTERS.

I added 12 SRB, 3 on each of the 4 tanks. And now, i have 4100 dv in worst case. Worst case because the higher i’ll be, the higher all my engines will be efficient. I think i will still have to finish the circularisation with the orbiter (hence the nuclear engines) but for a short amount of time. If you mind about the parachutes, i use a mod called “stage recovery which let recover part if you add the good amount of chutes. I have more than 60 chutes in this case… So now, i think that’s it. We are ready to launch. I haven’t yet planned the trip but i’ll do that on the refueling station. Anyway, i’m dying to launch this beauty.

8 The refueler tanker

As said before i will be short on dv for the injection burn around Moho, i need to add more tank. So i decided to add the refueler tanker. Defeating somewhat my challenge: i need to do a second launch but when it will be in LKO, i’ll attach it to the compound and it will do the journey with it.

There is nothing really interesting about this tanker. It is just a tanker… equipped with a senior dock on top to connect the base in lko.

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