I am full of grief and coffee

[Whackjob]

Ah. Odd. Not sure what happened to the link. Allow me to get the correct one and not linkitize it.

http://forums.randi.org/showthread.php?t=241636

Stand by! I am about to bludgeon you all with pictures of the MK3.

My latest attempt... I present to you, the Arkingthaad Mk3.

Edited July 22, 2013 by Aphox
Merged multiposts

[Thiel]

Were did you say you were going with that thing?

Oh and the fins on the upper stage are likely to cause trouble.

[Whackjob]

Using demo game for today, trying to get to the Mun. ... no luck. I suspect I am overdoing it.

[Boris_T_Roach]

yupp your rockets definetly show promise.. and struts... but surely you can squeeze a couple more SRBs in there? just for the added boominess when everything goes boom

Just use patience when flying to the mun, and be aware just how many times you will have to build a rescue lander in order to rescue the crew you've just stranded there... then another ship to rescue that crew too

Boris

[Whackjob]

Well, Boris, that post certainly shows foresight. I have just used my latest rocket, the Arkingthaad Type R, and put a Kerbalinain on the Mun. Unfortunately, I my descent stage ran out of fuel and I had to use my ascent stage to break my fall. He is stranded. I am not certain how I can rescue him. Assuming I land a vehicle there that can take off, how can I get him on board? ... have him hang on to the ladder?

I updated the Type R with one more layer of solid boosters to make up for the lack of fuel I had at the Mun. I do not know if this will be sufficient. The rescue mission is now entering orbit, but suffered an anomaly and damage on the way up. The mission is still a go.

Edited June 19, 2013 by Whackjob

[Pbhead]

To OP. One of the biggest problems with this game is that its advertisement videos show basically no gameplay whatsoever. just kerbals running around doing things. which, while cute to us players, does nothing for people looking to buy games.

[Whackjob]

Rescue mission has landed on the Mun. Unfortunately, it landed maybe 1/8th of the circumference of the moon away. Also unfortunately, I misjudged how far the ground is and landed hard enough to break a landing strut. Oh, and the booster engine.

So now the question is, two rescue missions, or do I run one guy over to the other?

[InfinityArch]

@Whackjob: That rocket is way overbuilt. I imagine that thing is shaking itself to pieces shortly after launch, amirite?

[zekes]

It's one thing to be wrong. It's something altogether different when you're wrong because you know you did something stupid.

I've seen KSP on Steam. I even watched the one video that was up there for it. You know the one... the guy takes his helmet off on the Mun. I saw it, I considered it, and I discarded it out of hand. I'd been burned by shallow, boring indie games before on Steam, you see. Not that that is any kind of acceptable excuse. And so I carried along, sans rocketry.

Then yesterday I run afoul of a certain JREF thread. Specifically, this one: JREF

The name recognition got me, I clicked the link to see what about this game had managed to entrall enough JREF posters to merit a multipage thread. And I saw those pictures. I read the enthusiasm people have for this game. And I reconsidered.

I went home that day, downloaded the demo for KSP, and took it for a spin. Specifically, a flat spin from about four kilometers up that ended in a fireball, a handful of crushed field mice, and a topsoil depth crater sufficient enough to give all the world's landscapers nightmares. I was enthused; the Kerban was dead. What I had initially took for a goofy, non-complexity based game completely devoid of realism or challenge actually concealed large measures of both.

So then the grief strikes. If I'd only been around a few months earlier, I could've been there, at the launch pad, with the rest of you, as this strange machine was fueling up. Instead, I have to cling meekly from the outside. Peering in through a tiny window. Wondering if you guys have coffee in there.

I bet it's great coffee.

So, that's it. That's my failure. I relapsed to the whole judging/book/cover combo fallacy, and my lapse is now revealed to all. I am sorry. I will make amends by buying this game. I will enjoy it. I know I will; I got three hours of sleep last night because I spent my usual scheduled coma time towards building a reliable heavy lift booster system. And now I post here, full of grief and coffee. I look on it as a learning mechanism; Even the finest of brews can come from the strangest looking grounds. You do a disservice only to yourself by opting out and not at least trying it out with a bit of half and half and sugar.

~Whackjob

Wow. Great narrative. Really well said. It even makes me feel bad for you.

Ill buy you another coffee

[Whackjob]

@Whackjob: That rocket is way overbuilt. I imagine that thing is shaking itself to pieces shortly after launch, amirite?

What? No. It flies quite solidly. The secret is the [X] shaped bracing. But that's the old Mk3. I've done marks 4-6 plus the "Type R" variant, which I just now scrapped. I'm working on something with a better lander.

[roosterr]

Hey WhckJob, use the '+' and '-' buttons to zoom in and out so you can get the full craft in the screenie. It also helps for building

My latest attempt... I present to you, the Arkingthaad Mk3.

[Uberick]

I feel ya dude; When I first started playing this game, I thought to myself "How have I not been playing this until now?" Such a great game.

Welcome to the party!

[The Jedi Master]

When you succeed in KSP, it feels great. When you fail, the fire makes it look pretty. Either way, you get AWESOME!

Welcome. Have some doughnuts with your coffee.

[Spatzimaus]

I suspect I am overdoing it.

Normally I'd say that there's no such thing as "overdoing it", but in this case, yes, you are. It's a very nice design, albeit much bigger than you actually need to go to Mun. Since you're still having some issues, though, I'll make a few suggestions.

First, you should always calculate the thrust-to-weight ratios of each stage. There are mods that can do this for you (like Flight Engineer), but it's also something you can do for yourself, like so:

From what I can see, your payload in the top two stages (everything other than rocket fuel, engines, or struts) masses about 2.0 tons, with nearly all of that being in the top stage. This isn't counting the 21 winglets (0.02T per) or 11 tricouplers (0.3T per) in the bottom stages, and I'll ignore strut/fuel line weights for now. So, the stages appear to go like so (masses are including all stages above each one):

1: mass 2.8T, thrust 50kN. TWR: 1.8

2: mass 6T, thrust 50kN. TWR: 0.8

3: mass 26T, thrust 800kN. TWR: 3.0

4: mass 80T, thrust 1720kN. TWR: 2.3

5: mass 144T, thrust 2580kN. TWR: 1.8

6: mass 285T, thrust 4515kN. TWR: 1.6

For TWR, a stage lifting off Kerbin should be in the 2.2 range, and anything below 1.5 is really bad. A transfer stage (something firing only in orbit after you've circularized) can be as low as you want, although you shouldn't go below 0.1-0.2 for practical reasons and a moderate TWR keeps it from getting too boring, while a stage landing on or lifting off from Mun should have at least 0.3ish and should ideally be in the 0.5 range. So what I can see is that your bottom two stages just aren't powerful enough, whereas your middle stages have far more thrust than they actually need. Your top stage is also overpowered, but considering that the LV-909 is the smallest engine you can get in the demo, it's understandable.

So, here are some suggestions:

1> In the #3 and #4 stages, you can use LV-909s to save on weight, since you don't really need that much power at those points and efficiency is more important in orbit. The big engines you're using are 1.25T or 1.5T, whereas a 909 is only 0.5T. On the #3 stage, downgrading the engines from the LV-T45s you're using chops 4 tons off the weight; 22 tons for 200kN is only a TWR of 0.9, but that stage just doesn't NEED anything higher and the fuel will last much longer. Between the 20% lower weight and a 10% boost in engine efficiency, this'll get you 30% further on that stage, and will help a bit with the lower stages as well. Once you get the full game, you can replace the engines in the #4 stage with LV-Ns, which are MUCH more efficient despite their higher weight.

2> Your #3 and #5 stages have too little fuel for their thrusts. Your 3 stage has 13.5 tons of fuel for 4 engines (3.375T per engine), and the 5 stage has 10 4.5-ton tanks feeding 12 engines (3.75T per engine); these numbers are just a little too low, given the high fuel consumption of the engines in question. The 4 stage is 40.5T for 8 engines (5.1T per), which is just fine in theory. The 6 stage has 25 4.5T (and one 2.25T) tanks for 21 engines (about 5.4T per engine), but it's not evenly distributed, which we'll discuss later.

3> I know we love saying MOAR STRUTS, but you might just have too many of them. Each weighs 0.05 tons, so it adds up quickly when you start making strut networks that complex on fuel tanks that small. When you transition from the demo to the full game, you won't have that problem as you'll be able to use 2.5m parts instead of the demo's 1.25m ones. (Or even 3.75m parts if you use mods.) You can shave off a little weight by removing the struts that you don't really need, but it's usually better to just simplify the design a bit so that they're not necessary in the first place.

4> The big problem I can see is your fuel transfer setup on the bottom (6) stage. All 21 engines in the first stage fire initially, but the outer 18 appear to have a different amount of fuel than the inner 3. It's hard to see whether your fuel is transferring inward (the 18 will burn out first, which means there'll be a period where only three engines are pushing but you're carrying the weight of 18 dead engines), outward (the inner 3 will burn out first), or a bit of both where some tanks go in and some go out. Regardless, that's bad. With more fuel lines you could make all 21 engines share a supply, so they'd all keep burning until the entire stage was exhausted, but it's still not the most efficient way to do things.

What we usually suggest is the "asparagus" design; the outer pods should be attached to the center with a radial decoupler (there's one in the demo, although the stock game has better ones), which you fire the moment the outer engines run out of fuel. This ditches the dead weight, saving a lot of fuel. In fact, if your outermost engine in the second stage are far enough from the center, they'll be able to fire once the bottom outer pods separate, so that it's not just 3 small engines pushing you to orbit. But that brings us to the final point:

5> Frankly, you could chop out your entire 5 stage and it'd probably still work just fine. That'd chop about 65 tons off your total weight, bringing the TWR of the bottom stage up to about 2.0-2.1. One issue you have is that your 5 stage has almost the exact same amount of fuel as your 4 stage (45T vs 40.5T), despite having more engines, which means that you're lifting an extremely large amount of weight on a #5 stage lacking in fuel. If you're going to do this sort of sequential staging, you want to have the weights and engine strengths taper down as you go up, but these two are too close. Ideally, you'd make the #5 stage bigger and the #4 smaller, but I'd look at just chopping out the #5 and making #4 a little bigger.

6> Likewise, you could probably just merge the #1 and #2 stages. If you merge the two stages, using a single 4.5T fuel tank instead of the two 2.25Ts, you save 0.5 tons from the removal of the second engine during the period where the #2 stage is still attached. The downside is that once the #1 stage separates, you'd be carrying along the weight of four landing legs (negligible) and the dry weight of a 2.25T tank (0.25T), so it's a tradeoff.

7> Put a stack separator just below the RCS tank, so that your final descent stage is only your command capsule, RCS fuel, and four RCS jets. Besides being a good emergency bailout mechanism, this minimizes the amount of weight you'd have to push if you ran out of rocket fuel along the way. On something that small, the RCS could get you all the way home from anywhere in Kerbin's SOI just using the "H" key to push.

8> I think you've got too much RCS fuel in general, especially in the lower stages. You won't be using RCS during launch, and even in orbit it won't take much before the lower stages are separated. A rocket, even one that big, can make do on only one or two of those 100-point tanks.

Regardless of what path you choose, your bottom two stages need either more thrust or less total weight, while your 3 and 4 stages can be toned down a bit.

Edited June 19, 2013 by Spatzimaus

[rryy]

My latest attempt... I present to you, the Arkingthaad Mk3.

~bunch of snips~

You may be taking the phrase, "MOAR BOOSTERS!" a bit too seriously.

I remember in the early days of me playing KSP, I also tended to overbuild rockets, but that makes mine look reasonable!

[Whackjob]

Thanks, spaz. I've scrapped that design completely, but I will absolutely keep your suggestions in mind.

[FlamedSteak]

The parts limitations on the demo most likely necessitates the need for slightly nutty designs.

The full version will give you more freedom and sane decisions to make. Until then welcome.

[Spatzimaus]

I've scrapped that design completely, but I will absolutely keep your suggestions in mind.

The most important bit of that post was to calculate thrust-to-weight ratios for each stage, with masses inclusive of all stages above it. In KSP, the surface gravity of Kerbin is the same as that of Earth (9.8m/s^2), so TWR is just (thrust of engines, in kN) / (mass of rocket, in tons * 9.8). And feel free to round that 9.8 off to a 10 to keep things easy. A TWR of 1.6 on that bottom stage meant that over 60% of your thrust was being used just to offset gravity, with less than 40% of your total actually accelerating you upwards. If you'd increased your thrust by 33%, keeping everything else the same, a TWR of 2.1 would give you almost twice the acceleration while only burning through fuel 33% faster, for a 50% improvement in how far you can go on that stage.

Now, watch out for the reverse problem; if your TWR is too high in an atmosphere, then you'll be spending way too much fuel offsetting atmospheric drag; this can be even worse than fighting gravity for longer, so you want to aim for the sweet spot in between the two, which falls pretty close to that TWR=2.2 I suggested. Ideally, you want to ascend along the terminal velocity curve (110m/s at 1000m, 140m/s at 3000m, 170m/s at 6000m; see the wiki for the full table), so just keep an eye on your speed during the ascent. If you're going well below 100m/s when you cross 1000m altitude, then you need more thrust, and if you're going 130 or more at that point you've got way too much engine power. It's usually better to have a bit too much engine, and just throttle down as necessary, than to have too little thrust.

[Whackjob]

"This end should point towards the ground if you want to go to space."

"If it starts pointing towards space you are having a bad problem and you will not go to space today."

Bonus points if you can guess the name of this rocket.

[Sir Nahme]

so many xkcd fans here XD lol

[Spatzimaus]

Let's hope the Up Goer 6 is more successful...

[Whackjob]

Take a look again at that picture. That Jebediah. I've seen him thoroughly horrified at something as basic as boosting orbit. But seconds from impact? He couldn't care less. This situation is obviously old hat to him.

Handles better than it should.

Finally, the rescue attempt is about to pay off. Provided I do not screw up.

My landing was neophytic and I without question burned up way too much fuel during the descent. But my landing was good enough to only require a 8.8km walk.

#EDIT: But there's nobody to take the walk. My Kerbonian appears to have died during the wait for a ride home. :<

#EDIT2: Pouring a cup of coffee in salute to the brave soul who decided to stay in the can for good. Salud.

Edited July 22, 2013 by Aphox
Merged multiposts

[zekes]

Handles better than it should.

This is exactly what my 13.0 ships looked like... big, strutty, overstaged, and prone to crumpling.

Keep up the good work!

[Razor235]

Whackjob, would you mind sending me the .crafts for those rockets? I just want to screw around with the biggest Mun rockets I've ever seen.

[Whackjob]

Whackjob, would you mind sending me the .crafts for those rockets? I just want to screw around with the biggest Mun rockets I've ever seen.

Sure. Gimmie an email addy.

Show me what ya do with 'em, Razor.

Edited July 22, 2013 by Aphox
Merged multiposts