Inexperienced Kerbonaut Questions

[Keymaster89]

Hi everybody!

I'm new to the game and after a dozen greatly rewarding Mun/Minmus landing and back to Kerbin flight, i'm starting to know the game, so i'm now assemblying a mid class fleet of vassels: modular orbital Mun base with lab, modular refueling station in KNO and few fuel modules without engines with heavy engine cargo ship to deliver it (just unlocked LV-N yesterday )

I'm not a math guy, maybe i'm wrong (and probably i am) but for me Isp and TWR are just power meters: "ok, this station is pretty big, so for launch it i need the 5 big one engines with solid all around... naaaa 7 are better!", i like to assembly, launch and see what happens, and if i crush, then LOL and revert to Vehicle assembly This is the way I play.

Those are some questions about the game that i still don't understand... i hope someone can help me!

1)I placed my brand new base at Mun's orbit with a lab and plenty of fuel, in order to make my single trip lander reusable and perform multiple landing before coming home. Then after first land i docked at the station. After analizing all i can with the lab, and sending data of crew report and EVA report, temperature, sismic that I can store easily, i came to a stop in my mission: when was the turn of my goos, sc9001 and soil sample, that are the real science cake, i realized that if I transmit the data, i can't keep the big chunck of raw data inside the lander, as i have to clean it in order to reuse it. So I planned a new lander and a new base module, in order to bypass this issue and by tonight i’ll have it in place.

The new lander will have a cockpit and a solidal engines body, plus a docked sc9001 with sensors array on it, and the base will get a new module that is a parking for 8 of this docked sc9001 parts.

Every landing, i’ll undock the science module from the lander and dock a fresh new from the base module for another land and go on.

So, now I have the final problem: As I resolved goo and sc9001 data store, I didn’t find a way to store surface samples, I didn’t even find a way to move it from the cockpit once I reenter the lander on the Mun's surface. There is a way to move this sample cockpit to cockpit, store it in other ways or stack it in the cockpit (didn’t tried it actually…)? Or my entire project of a reusable lander is just a dream that have to stay a dream?

2)I tried hard to understand the difference between Inline Reaction Wheel and Inline Advanced Stabilizer, but as far I can see, the only two differences that I manage to find are that the advanced one have 0.2 more mass and a really better looking texture, but that don’t explain why this should be more advanced… as this one is heavier i expected to add more torque, but… they’re the same so… They have different behavior, maybe one is better to fight th Kraken than the other or are placeholder for something in the future?

3)Are RCS truster in 3x and 6x simmetry good? I always try to place them 4x or 8x because this way I have truster directly pointed in xyz axes and I feel unconfortable to not place them that way…

4)Have the landing struts any max load value? Sometimes I add couple of for the sake of not break someone in the landing.

5)What kind of vassel Ion engine is designed for? I find it hard to place in a lander, in a ship with orbital needs or even heavy load ship, not to mention on stations which should be, you know, stationary… I thought trans-planet propulsion was a good choice because they need time to operate as their’re near 0.5 trust, but on heavy vassel that trust is kinda nothing I suppose. Maybe is a way to hybrid Ion-nuclear vassel? I’m confused.

6)I find myself confused when I have to choose what communication device should I use… As the wiki say, the comm16 is the slowest and require the lowest amount of energy, the DTS have high transmission rate and medium energy consumption and the comms88 work at medium speed with loads of elettricity… I find this strange because the comms88 is the last of this to be unlocked, so why is worst than the DTS? Have the communication devices some sort of max range of transmission (I haven’t already left Kerbin orbit to test)?

7)Given an amount of fuel shared between all engines, is better have 3x LV-909 that burn longer at 150 trust or 5x Rockomax 48-7S that have the same trust power but consume a little more with triple TWR? can't understand what combination is better on a lander...

Thanks everyone ahead.

Edited January 14, 2014 by Keymaster89

[Trueborn]

1) With a fully staffed (2 Kerbols) science lab, you can not only process the reports before sending them, but you can also clean and re-use the one-shot experiments.

2) They used to do different things, but now the only differences are as you pointed out.

3) I always try to do 4. Other configurations make translation difficult (though there are some RCS balancers out there to help counteract that problem).

4) Yes, but I don't remember off hand. For mun/minmus landings, 3 or 4 should be fine. Just keep your speed down on landing.

5) Very, very small ones.

6) A lot of people find that its an odd choice from a game balance perspective, but yes. The first transmitter is the most efficient, while the last one is the least. If transmission time is relevant though (say for a flyby mission or on descent), the large dish can be useful.

7) Depends on where you're landing. Check out Engineer Redux. This mod calculates delta V and TWR for you in the VAB, and you can change the body you are concerned with so you can make sure your lander's TWR isn't excessive. Technically you need it just over 1.0, but 3 or higher is better for actually slowing your descent.

[sciguyCO]

To cover more of your question in #1:

A Kerbal on EVA can retrieve science from any part that can store it, including the command modules.

So to move your surface samples, EVA, right-click the command module, and then "retrieve experiments" (I think that's the wording used). All the science results are now "stored" with the Kerbal. When he enters a command pod, all the science with the Kerbal automatically gets stored in the pod (I think this includes the lab).

I had a similar setup in a previous save. I had a "science station" that had fuel tanks, the science lab, and a lander. In addition, I had a return vessel to handle refueling the station and bringing science back to KSC. My process was:

1) Send lander down. Gather all the science readings, EVA reports, surface samples, and crew report. Only transmit the crew report.

2) Launch and dock with the science station.

3) EVA the kerbal, retrieve all the science from the command pod, sensors (making them ready for re-use), goo containers (making them inoperable), and sc9001 (making it inoperable).

4) Send the kerbal to a second command pod which is my Kerbin return vessel, storing all the data there. As far as I know, there's no "data limit" in modules, so you as long as there are no duplicate results, they get stored. So the pod can hold "temp reading from Mun Highlands" + "temp reading from Farside Crater", etc. You cannot have two "temp readings from Highlands" though (this gives you the "dump experiment" dialog).

5) Use the mobile science lab to clean the goo cannisters and SC9001. You can do this by right-clicking each component, or I think there's a "Clean experiments" option on the lab that resets all science components docked with the station. This does require electricity (make sure your solar panels are deployed) and having two Kerbals inside the lab. I don't bother "analyzing" the results for transmission since the plan is to take everything back.

6) Refuel the lander's tanks and EVA a Kerbal back to it.

8) Repeat from #1 at a new biome until the station can no longer refuel the lander.

9) Send return ship back to kerbin with all the science in its command pod. Retrieve it for science.

10) If desired, send up another "return vessel" to refuel the station to continue lander missions to the surface.

[Keymaster89]

Thanks guys for all your answers

@Trueborn

5) Like mini probes? that is sad... i thought that when i got the pieces i'llstart building an iper-efficient carrier with 25-35 ions but if they are that bad... i guess i will try for fun in sandbox ^^

@sciguyCO

Ho cool! i didn't know that! so i haven't to change anything that i already have! it's just a question of go on EVA! good for me! (even if i was excited to build that parking module with material labs to dock, that was a good design,at leastin my mind, i will take it in mind for future upgrade of the game, who knows what will happen?) BTW, there is a way to refuel the EVA pack of kerbonauts? maybe i have go near a monopropellant tank and transfer like any other tank?

[Trueborn]

They actually take quite a bit of energy to run, so for 25-30 you'll need a lot of solar panels. Also, you end up doing really long burns (30 min or more, no time acceleration) for heavier vessels. Still, its an interesting challenge to design something useful with one. I'm sure you can find some good ion probe designs around on the forum.

[Tank Buddy]

I'll answer a few:

TWR is how much thrust you have compared to the WEIGHT of your craft. It matters most when landing, and smaller moons/planets have less gravity, and therefore a ship will have a higher TWR on a body with less gravity. The higher the TWR, the higher the acceleration you will have, so adding more engines will will make your ship speed up or slow down faster. Keep in mind you can go farther with one engine than with more than one, as long as you don't need the extra thrust.

Isp is a measure of efficiency used in the Delta V equation. The higher the Isp, the more efficiently you will burn fuel.

Delta V is "Change in velocity" and in space you need to change speed and direction (velocity) to go places, like the Mun. Delta-V is a good measure of where your ship can go.

2. The Inline Advanced Stabilizer was the old ASAS that allowed you to maintain heading. Since the SAS overhaul, it has the exact same function and torque as the Inline Reaction Wheel, to add torque, and as you observed it weighs more. Effectively the Inline Reaction Wheel is superior in all ways and the Inline Advanced Stabilizer is pretty much useless in that respect.

3. You are right, if you plan on using RCS for translation or rotation, having the thrust aligned with the axis is more efficient. 4 RCS blocks are best because they point directly with the direction of travel. You can add more than 1 pair of 4 in different places along the rocket as long as you keep them pointed in the right direction. If you're interested in the future this mod will help, but you probably should wait before using it: http://kerbalspaceprogram.com/rcs-build-aid-v0-2/

4. Yes, after a certain weight (the breaking force is different on different bodies with varying surface gravities) Usually I can just know by looking at the craft how many and what kind of landing legs I need. Experimentation/failure will help you with this, but if you want an exact weight I'm sure its written on the wiki or forum somewhere.

5. Ion Engines are pretty much useless for normal uses because of the minuscule thrust, which makes landing on most bodies difficult if not impossible (Because of the TWR), and burn times to chance speed are long and make gameplay boring. The only place that I found them to be plausible is on is Eve's moon, Gilly, because it has almost no gravity and the maximum orbital speed is probably 20 m/s, so .1m/s of acceleration from ion engines is manageable.

6. Essentially the first Antenna you unlock is the best. Features have not yet been implemented that give the others advantages.

7. I did a similar investigation for these engines for my science fair project, and I found that if you only use 1 engine and you have 2 identical rockets, they will produce the same Delta-V if you have about 500 liters of fuel (I forgot the number). If you burn less than 500 liters, the 48-7s will give you more Delta V.

I'll have to do the math some other time, so I'll get back to you, but essentially if you burn less than a certain amount of fuel, the 5 48-7s's will be better. That's a very good observation of yours. You could be a future Aerospace Engineer!

Message me and I'll do the calculations to see how much fuel you'd have to burn for the 3 Lv-909s to be better.

[Keymaster89]

@Trueborn

well... yes, lots of panels, but imagine how cool is this gigantuan ship with massive arrey of ions and solar panel flags all over the place? The most challenging thing for me will not be the construction of the ions, but instead the placemant of solars, as if i understand correctly, are 1 gigantor solar = 1 ion, so u have to cover entirely the ship with gigantors, normal panels, RTGs and massive batterys, making the ship a real solar farm! placement is crucial as the panel cover each others, surface is limited and u also need space for docking. i love this project already i'll make the biggest solar flower ever and if i manage to do it in some convinient way i'll never use liquid fuel again

@Tank Buddy

Thanks for your detailed answers!

OK, so: TWR is directly tied to the acceleration of my ship. The higher the better, but better accelleration, mean that i need more engines, that needs more fuel (or at least tanks), both generating mass that need more engine to be trusted. So the ideal is not growing fat but proportionate things by your needs, right?

"Keep in mind you can go farther with one engine than with more than one, as long as you don't need the extra thrust." because of the lower mass that u gain for remove the extra engines and related infrastructure to place them?

7)Well, as trust power is the same in both configuration, i'll get the same power, but 3 times better TWR with 48-7S SHOULD allow me to a better construction, also beside of fuel mass, which is good mass, i add dead mass of the tanks, that is bad mass.

Actually i'm using 3x LV-909 radial mounted with 3x T200 + 6x struts + 3x mk25chute on top of them attached to the lander with 1 R25 that give me a total dead mass of:

(3 x 0.5) + (3 x 0.125) + (6 x 0.05) + (3 x 0.2) + 0.55 = 3.325 t empty

(3 x 0.5) + (3 x 1.125) + (6 x 0.05) + (3 x 0.2) + 0.55 = 6.325 t full

with 270 of fuel that burn for a total time of: (i think that t/s = 0.0131 is fuel consumed in a sec so)

270 / (3 x 0.0131) = 6870.22s (that sound so wrong to me…)

INSTEAD

I can have 5x 48-7S (4 radial 1 inline) with 5x T100 + 5x OscarB (for adapt engine size) + 5 ROUND8 (for compensate the lack of fuel) + 10x struts + 5x mk25chute + 2x StratusV round (for save the simmetry) that give me a total dead mass of:

(5 x 0.1) + (5 x 0.0625) + (5 x 0.015) + (5 x 0.025) + (10 x 0.05) + (5 x 0.2) + (2 x 0.235)= 2.9825 t empty

(5 x 0.1) + (5 x 0.5625) + (5 x 0.079) + (5 x 0.136) + (10 x 0.05) + (5 x 0.2) + (2 x 0.235) = 6.3575 t full

With 303.675 of fuel that burn for a total time of:

303.675 / (5 x 0.0102) = 5954.41s (that sound to me even more wrong but not surprised is smaller)

In general, the calculation seems way better for the 5x 48-7S, beside that burn time calculation that I probably miss something, the PROS are:

-less death weight = more power

-more fuel capacity = more duration

-fuel consumption more efficient due to augmented Isp = even more duration

-more stable because of increased land struts and really low CoM = easier landing

-1 more chute = softer landing

-a bit more but really similar full mass = not different to what I already have

CONS are:

-need more precise burn due to tripled TWR = probably I’ll need corrections

-5 engine drink fuel faster than 3 even if smaller and efficient = lower total burn time = probably I’ll not have fuel for corrections

-I can’t fit T200 because the inline engine will touch the ground, also tons more mass = fuel capacity upgrade is out of discussion

-no much space for RCS trusters due to the new StratusV = I have to build this with a caliber

-I’m really worried = I’m sure I miss something in this mechanic that ruin all I said until now.

What i'm not considering in this plan?

Edited January 10, 2014 by Keymaster89

[Trueborn]

Read this tutorial: http://wiki.kerbalspaceprogram.com/wiki/Tutorial:Advanced_Rocket_Design

That will let you calculate the delta V for each proposed design. Delta V is a much better indication of where you can go than total burn time. Then you can look at a delta V map to see if you've got enough to go where you want to. Then you can decide which is more appropriate. If you've got plenty of dV with the design with more thrust, that'll make landings a bit easier.

And if you would rather not do the math by hand each time, you can use Engineer Redux to calculate delta V in the VAB as you build. It can really help you tweak your designs.

Edited January 10, 2014 by Trueborn
URL fail

[thereaverofdarkness]

1.) You can transfer your reports and samples from one command module to another via Kerbals. They can carry the reports on EVA from one location to the other. Simply have the Kerbal next to the command module, then right click the module and choose "take reports".

2.) no difference except mass, probably placeholder

3.) 3x and 6x symmetry work fine. The game automatically adjusts for their placement. You will get less thrust for greater monopropellant use in some directions though.

4.) Landing struts in 0.23 can't hold your craft upright. They have been made incredibly weak. That being said, they still work great for landing. They pad the impact of your ship. Engines work great for landing too, but the landing legs stick out to the sides and can offer better support if you land on a slope or just have difficulty making your craft come down straight.

5.) Ion engines give you super high deltaV with super low TWR and they demonstrate profoundly how these differ. You can get a decent TMR (thrust to mass ratio) on an ion-powered ship if you make sure the mass of the ship is almost entirely ion engines and solar panels. If you use a very light probe core, not too much battery weight, only one xenon tank but several ion engines, and almost no mass in structural components, you get a ship that can accelerate at a good fraction of 1m/s/s. A ship like this can land on very low gravity worlds like Minmus if it maintains good sunlight and is able to run the engines for long periods of time during landing. You can save mass on your ion probe by taking some solar panels off and using lighter batteries instead, and just burning in short bursts and time accelerating while the batteries recharge, but you won't be able to land on much other than Gilly. Finally, you can put on tiny science instruments like a thermometer, barometer (probably won't need that one!), seismometer (for landings), and negative gravoli detector, and a little antenna, which brings us to...

6.) I suspect the plans are in the works to make the less efficient antennas have a longer range. The middle one does transmit faster though. Perhaps the basic antenna is for low orbits with a range barely large enough to go across Jool, the second is for intraplanetary (or inter-munal if you will) with a range maybe across the Joolian moons, and the third is for interplanetary, with a range extending across the entire Kerbolar system. But currently they all have infinite range.

7.) having a very high TWR for landers is a good idea. It not only makes landing easier, it can save lots of fuel. You don't want all your weight in engines though. I think both of those engine setups are great - but I have a preference toward the LV-909s and will use Rockomax 24-77s to add extra thrust if I run out of room for LV-909s and want a higher TWR. I try not to use the 48-7S because its TWR is too high for its Isp, and it seems like a cheaty engine. My preferred TWR for landing is at least 10:1 (in relation to the body being landed on) though I will shoot for 20:1 if I can get the fuel/engine mass ratios to work out. 3:1 is okay if you're landing on a high-G place like Tylo but I wouldn't go any less for airless landings. For Tylo I'd still try to get at least 5:1 TWR for landing. It's really important that you don't have to fight gravity the whole way down. With a 20:1 TWR you can first place yourself in a low orbit, then bring your periapsis just below the surface, then gradually descend, shooting over the terrain at orbital veocity. You will pick up very little descent velocity this way, and you can wait to burn the engines until you are pretty close to the ground. Then you just thrust hard and keep your navball heading centered on the yellow-green tri-point circle (retrograde vector) as you come in for a landing. Watch the surface rushing up under you--it should come in at a relatively constant rate if you are thrusting right. If it starts to come in slower, decrease thrust. If it starts to speed up, increase thrust--nose up (point toward middle of the blue on the navball) if you have to. Once you get the hang of this trick, you can save a ton of deltaV/fuel on landings. It works best for medium-gravity airless worlds like the Mün or Vall, but should work on Duna and might be useful even on Bop.

Best lander engine for Tylo is the Rockomax 48-7S, but you can land on it with 24-77s and LV-909s.

Edited January 10, 2014 by thereaverofdarkness

[Keymaster89]

@Trueborn

Good point... i didn't want to go into mods at my first game for try it as it is, but for this, that add only a build assistant i should give it a try.

(BTW, i'm a mod lover guy, after the first update i'll definetly start a new career and try tons of mods XD)

@thereaverofdarkness

4) how do u use it beside of landing?

6) i came to the same conclusion the first time i compared them... the only way to get this correctly scaled is to give them max communication range

7) that is pretty intense! rushing the ground at that speed! i prefer to slow down my orbit until i get a 45° descent angle, around 10km kill my orizontal velocity and then control only vertical velocity to the ground... work really good for me.

[thereaverofdarkness]

You can use landing legs for keeping your stuff upright. It'll sag under the weight unless you're either in low gravity, have a very light ship, or have an inordinate number of landing legs.

I used to stop my orbital motion completely and come in for a straight landing, but I saw Scott Manley do the high angle of attack landing and I wanted to try it. Turns out it's actually pretty easy to execute if you can remember all of the steps on the fly.