I'm having a bad time.

[rakutenshi]

Just a point of clarification here- since you're using a modded install - you're just using standard LFO engines, right? not realfuels or anything similar, changing the fuel types and tech levels for engines with realfuels installed can have.. varied results.

[sal_vager]

Yeah this really belongs in Gameplay so I'll move it.

To me the craft looks like the center is just too heavy for the single engine, I'd shorten it and lengthen the boosters.

[KerBlam]

3 hours ago, r4pt0r said:

your numbers confuse me. I just keep tweaking the design until it works.

My numbers confuse me also, and I know you're all over it.

3 hours ago, Streetwind said:

A good start is to look for the mod's forum thread here on the KSP forums. Since all KSP mods are required to declare some sort of license, you'll find almost no mods that don't have a forum thread, if only for that reason. And google finds them reliably.

The reason you can't find it on Curse is because it doesn't appear to be on Curse. Some modders were dissatisfied with Squad choosing Curse as the official mod repository and simply don't use it. A community-built alternative called KerbalStuff manifested, and you'll find a lot of mods there. KJR also uses KerbalStuff as its primary mirror.

There's also CKAN, a community-maintained mod manager that can download and install mods for you and automatically checks for incompatibilities. It isn't perfect, and doesn't recognize all mods under all versions, but for a lot of people it's the preferred method of modding KSP.

I googled and found it tankyou. I also remember CKAN, I'm not using it at present, but I may do.

2 hours ago, rakutenshi said:

Just a point of clarification here- since you're using a modded install - you're just using standard LFO engines, right? not realfuels or anything similar, changing the fuel types and tech levels for engines with realfuels installed can have.. varied results.

Yes just standard stock engines and everything, I'm using Vens Stock Revamp, and that's it.. oh and KJR now too...and MechJeb, but not like that.

[KerBlam]

It goes like this:

1. Doesn't leave launchpad > not enough power > add more boosters >try again

2. Gets off launchpad > uncontrollable > not enough authoritah > add more drag > try again

3. Gets off launchpad > controllable > doesn't make it past atmo> not enough fuel > try again

4. See number 1.

5. scour internet for clues because game gives zero help.

 

Keeping in mind I am playing CAREER. If I'm in sandbox I can pretty much do anything, so I will probably abandon career. I would hate to be someone new to the game thinking 'I'll just try play the campaign on NORMAL' because I guarantee NOBODY except Elon Musk will like that. 100% guaranteed drop the game and never pick it up again after 100+ dismal failures to make orbit with more payload than a mark I cockpit on a stick.

I'm trying to get some little green men into space, Excuse me while I just reference my handy astrophysics textbook and whip out a few calculations on my faithful old Casio.

Oh dang I'm not having fun anymore, what happened?

Somebody sucked the fun out of KSP, that's what happened.

EDIT: Sorry... Sorry... Venting after sooo many unsuccessful attempts.

I installed KJR and removed the struts, no wobble anymore but not too much different in the flight profile, still better than stock.

I lengthened boosters which (predictably) lowered my TWR. I have no idea what to do.

Edited January 8, 2016 by KerBlam

[bzimac]

I think that TWR of stage 3 is causing most trouble.   1.04 is simly not enough during the ascent, altough it should be good enough in space.

As sal_vager already suggested, you should shorten center stack a bit while adding more fuel to the boosters to compensate in delta v.

Edit: On many rockets it is a good idea to tweak the thrust of SRBs. If they burn longer that means that liquid engines will get to use up more fuel and have better TWR in the next stage.

Edited January 8, 2016 by bzimac

[Rocket In My Pocket]

Any chance of uploading the .craft file?

If you can't be bothered with an upload site, just open it with notepad and copy paste all the text here. Preferably under a spoiler tag because it's rather long.

On a side note, I can't recommend KER mod enough, I have both that and Mechjeb and I just find KER is so much more user friendly and helpful when designing a ship.

[ForScience6686]

I would try and lift off solely on Srbs, that will give you cheap power and you can save your engines for higher altitude where they are more efficient and more powerful.  Add a couple more Srbs and throttle them down to prevent going to fast to low.

[Gojira1000]

In my sledgehammer-style engineering I'd jam more hammers on it, so your liquid stage would ignite later and higher. The rocket in https://www.youtube.com/watch?v=tXyRrtNBI3M is reasonably early tech, and I was using that for a Mun rescue and multiple other things. It also had a low TWR and dV issue, thus the secondary SRBs on it. I wouldn't use that ship for Kerbin rescues, but maybe it'll spark some ideas?

 

As I look at it, the tourist bus in this one is a better example - https://www.youtube.com/watch?v=LP22gdBC7Zo

Edited January 8, 2016 by Gojira1000

[Rocket In My Pocket]

Here's an example of a 4th tier (It has a Mechjeb/KER module on it just fyi, should work fine without either.) rescue ship I whipped up real quick, just tested it and it'll reach a stable orbit of 80km AP/PE with about 1,300 m/s DV left. Should be enough to rescue some Kerbals in LKO.

Craft File: https://www.dropbox.com/s/tucb66ycaze32y2/RescueExample1.craft?dl=0

Feel free to use it, change it, or just compare it to your own design!

Edited January 8, 2016 by Rocket In My Pocket

[Aethon]

 

Hopefully you have some probe cores unlocked.  This is my early career rescue craft.  It has a probe core in the service bay and launches unkerbed.  A swivel powers the main stack after SRB burn out.  The SRB's are tweaked to run 2 at a time, and the second set is thrust limited to keep TWR reasonable.  An LV-909 powers the orbital stage.  Bigger is not always better. 

Don't give up.  It feels sooo good when you finally make it work.

 

[rakutenshi]

Build your ship from the top down.

Try to make your payload as light as possible to accomplish your goal (unless you'r whackjob, or someone like that, then make it out of boiler plate steel with room for 50 and it's own cable tv company) 

build your manouvering stage with the payload, this is what the LV-909 Terrier excels at. You should easily be able to get a LKO rescue ship that has around 1km/s dV to play around with, build your lift stage to get this into orbit without even touching the fuel in top stage. 

If you're good at making smooth gravity turns and sliding into orbit, you don't have to worry quite so much about TWR, however, if you have too steep of a trajectory, you need to make sure you have a very high thrust to weight ratio - this will allow you to make the circularization manouver in less time.

SRB's are cheap, powerful, but very heavy, if you haven't upgraded your launch pad, you'll want to stick with liquid fuel. 

 

This isn't meant to be critiques, just general advice, maybe some of it will be helpful.

Also - does anyone else think we should get a :dv: emoticon that displays "Δv"?

[swjr-swis]

@KerBlam Don't give up, you're getting a lot of good tips that should enable you to do this, and it's worth climbing that learning curve. Wanting to have fun in this game certainly resonates with me, I avoid playing too 'seriously' even though I like playing in career mode and goof off quite a bit. In my experience, following the basic principles and tips already listed in this thread makes it possible to get that or a very similar rocket into a good rescue orbit.

I am really puzzled as to what is causing the issue with your rocket though. I tried rebuilding your rocket in a pure stock 1.0.5 install, and test-launched it to see. Tl;dr: although a slight bit wobbly, and doing a less than optimal ascent, it made a 95km orbit with 332/360 LF left on the Terrier stage (iow. I only barely needed the Terrier to circularize). On the first try. It is absolutely possible.

 

Having only your picture to work with, I'm not sure I managed to recreate your craft well. Do you use some type of retexturing mod? Some parts that I'm pretty sure are there don't look much like my pure stock versions - like the Hammer SRBs and the TR-18A stack decouplers, and the nosecones are grey in yours when stock is blue.

• It's unclear what's on top of your command pod. I think I can make out an Mk16 parachute, but what do you have between that and the pod? Is it two small inline reaction wheels? It's too high to be just one wheel, and the small inline battery is not in the first 4 tiers. I placed two wheels.
• Also, your stack details indicate there's three parachutes, but other than the Mk16 on top, I can't tell where the other two are or what type. I placed two large radial chutes in 2x symmetry on the sides of the pod, close to the top. Doesn't look like yours but at least it totals the same nr of chutes.
• I think I see a small 1.25m service bay directly under your command pod. What does it contain? I crammed it full just in case: two octagonal struts in the center nodes, holding 4x Z100 batteries, 2x SP-L solar panels, 4x Illuminators Mk2, and even 4x LT-05 landing struts. Pure conjecture and unnecessary for a rescue mission, but I had to take a guess.
• I have no clue what you have directly under the service bay. From the stack details, it can't be an engine. A fuel tank in that position wouldn't make sense, and it doesn't match the FL-T200 anyway. There's no cylindrical crew cabin of that size. So... a Science Jr? Not much use for a rescue mission, but it's the only thing in the first 4 tiers that looks close enough.
• Under that, I think I see the shroud of a 1.25m heat shield. Did you leave all the ablator on it? It probably does not need all of that, but in my version I left it all on just to test with max payload mass.
• Then there's two FL-T400 tanks and a Terrier.
• From the stack details, there has to be a stack decoupler under the Terrier, but I don't see the typical black/yellow diagonal pattern of it. I used the TR-18A.
• Then another 4x FL-T400 tanks, with a T30 Reliant as center engine? Not entirely clear, but it's the highest thrust choice, and with the fins you don't really need gimbal anyway.
• LF Boosters appear to be on TT-38K radial decouplers, 3x FL-T400 tanks under a nosecone and a T30 Reliant engine. Two of those in 2x radial symmetry.
• SRBs, from the height of them, must be the RT-10 Hammers, but they don't look like that in my game. Attached with TT-38K decouplers and topped by a nosecone. Again 2x of them in radial symmetry.
• And you have what I think is the regular tail fin, in 4x radial symmetry, attached to the bottom of the center stack, diagonally between the boosters.
• Contrary to yours, I used zero struts, and being pure stock, I have no KJR (I basically wanted to see how structurally problematic it would be to fly strutless).
• I did no optimizations at all: no pre-leaning, all engines at default full thrust, all tanks fully fueled, full monoprop in the pod.
• I rearranged the staging sequence to match yours.

 

So, based on the above assumptions made from your picture, I build the craft and got the following launch out of it, first attempt:

 

Like I said, I really didn't feel like I had to try very hard. It was not an optimal launch, there was some wobbling, and a bit of lagging control authority, but letting the rocket follow prograde for a natural gravity turn and staging whenever stages flamed out did most of the work for me and kept things pointing to space.

So unless you tell me I have the build completely wrong, or you have some seriously massive stuff crammed in the service bay (or that mysterious part under it), I honestly don't understand why your rocket doesn't make it to orbit. Either your ascent profile must still be way off, or maybe more likely, some mod is seriously interfering, are the only things I can think of.

Btw, there's no rescue capability in this build, no place for extra Kerbals. So.. replacing the Science Jr by the small Mk2 can is probably a must to rescue anyone from orbit with this.

Craft file: KerBlam I

 

[Plusck]

It seems nobody has said it yet but:

Scott Manley's videos are now completely out of date. [edit: my bad - I see he has done a few videos since version 1.0 came out dealing with the aero changes. Still, I think it is important to view his videos in the context of the development of the game, so a lot of what he does in them will not work quite as expected in the latest version. That said, I stand by the following: ]   Use them for ideas, yes, but not for things like how to deal with the atmosphere.

Anything that you see that is prior to 2015 that talks about how to do a gravity turn is virtually guaranteed to be wrong.

If your boosters are properly attached near the bottom, maybe with a single strut at the top for very tall stacks, and if you try to stick to prograde all the way up (so you start with a couple of degrees east as soon as you leave the launchpad) then you shouldn't suffer from wobble and you shouldn't need mods to help you get to orbit.

I tried building your rocket, without all the struts. KER gave me a dv of about 5700 m/s.

There wasn't really a problem with wobble as such (though there was some). There was a serious problem of excessive control with the tail fins.

Tail fins are not meant to be used on rockets - they are far too powerful at rocket speeds. SAS was absolutely disastrous with them, so I just deactivated it and went up manually. It was a horrible flight profile but it worked fine.

My second problem was working out what you have at the top of your rocket. I tried with a crew cabin, and that was what gave me about 5700 m/s dv.

Then I thought it might be a Mk1 liquid fuel tank. That would explain some of the dv loss since it is just dead weight for your rocket: without oxidiser it is useless.

So I built a second rocket with the Mk1 liquid fuel tank and changed the tail fins out for the other tech level 4 control fin. It was still massively overpowered but it was better. KER gave me a delta-V of 4,800 m/s.

However, in your pictures I don't see any separator under your heatshield or under whatever that top white section is. If there isn't one, you're lucky not to have made orbit since your tourist(s) would have died coming down anyway : D

 

So what can I suggest?

First, you don't need mods. They are not good for new players because you need to get a feel of what is happening.

Without mods, I don't think you would have built such a huge rocket. It would have been smaller, it wouldn't have lifted off the pad with whatever all that weight is up top, and you'd have found and sorted that problem rather than simply making it huge. You wouldn't have had the dv info, specifically, but your experience with previous builds would have told you that something was wrong.

 

Second, there is no need for such tall rockets until much later in the game, when you have bigger (and stiffer) parts. Using a mod to make your rockets stiffer is not really a help, because a squatter and sturdier design will be cheaper, lighter and get you to everywhere you want to go anyway.

 

And finally, read the parts description! The tail fin is clearly described as being for aircraft. Sure you can put it on a rocket, but 5 seconds of flight should be enough to tell you that it is massively over-steering.

Edited January 9, 2016 by Plusck

[swjr-swis]

19 minutes ago, Plusck said:

I tried building your rocket

We had the same idea.

 

19 minutes ago, Plusck said:

My second problem was working out what you have at the top of your rocket.

I'm glad I wasn't the only one having trouble with that. I am still not sure what that part is. What did you place on the nose btw, under the chute? A probe core? Is that in the first 4 tiers?

 

19 minutes ago, Plusck said:

However, in your pictures I don't see any separator under your heatshield or under whatever that top white section is.

Yeah I can't see them either, which makes me think he uses some retexturing mod at least. The stack details on the right show that there's decouplers, so they must be there.

 

You chose a T-45 as center engine, where I think the bell's edge in his pic seems to be the same size as the LF boosters, so I picked the same T-30. It's hard to tell from that angle and mostly hidden behind the Hammer.

I also notice you make it stage the center engine from the start, but his stack details show it as off until the LF boosters are decoupled.

Edited January 8, 2016 by swjr-swis

[Rocket In My Pocket]

For everyone speculating on why his parts look odd who might'ave missed this post:

9 hours ago, KerBlam said:

I'm using Vens Stock Revamp.

http://forum.kerbalspaceprogram.com/index.php?/topic/83696-105-stock-part-revamp-update-191/

Edited January 8, 2016 by Rocket In My Pocket

[Plusck]

26 minutes ago, swjr-swis said:

We had the same idea.

 

I'm glad I wasn't the only one having trouble with that. I am still not sure what that part is. What did you place on the nose btw, under the chute? A probe core? Is that in the first 4 tiers?

 

Yeah I can't see them either, which makes me think he uses some retexturing mod at least. The stack details on the right show that there's decouplers, so they must be there.

 

You chose a T-45 as center engine, where I think the bell's edge in his pic seems to be the same size as the LF boosters, so I picked the same T-30. It's hard to tell from that angle and mostly hidden behind the Hammer.

I also notice you make it stage the center engine from the start, but his stack details show it as off until the LF boosters are decoupled.

Ah well, you were much more thorough than I was. It didn't even occur to me to look at the staging icons, which was a bit stupid.

I placed an OKTO under the parachute since that's what it sort-of looked like and that's what I would do. Since there was no sign of solar panels, I crammed the service bay full of the basic battery. Stupidly, I didn't bring up the resources window during flight, so I wasn't watching electricity levels.

However, you are right that it is not tier-4 tech. It is tier 5. However since I couldn't work out what that top white section was, I suspected that it might have been unlocked...

I accidentally sent up Valentina on the first flight, so she had piloting abilities not necessarily available at that level in career. However, the steering was so excessively overpowered that I ended up shutting her controls off and doing it myself very early on. : D

 

edit: P.S. as you might have guessed, your analytic post wasn't at all visible while I was writing mine. Luckily in fact, because it was so exhaustive I'd probably have given up in disgust ; )

Edited January 8, 2016 by Plusck

[Waxing_Kibbous]

Watch this video: https://youtu.be/1v1ZLXLBMQo?t=243

Use this Rocket (which is a stupid amount of overkill but meh, free crew with little hassle is worth it. That is the K2 command pod, only because I use pilots as much as possible):

[KerBlam]

You guys are awesome. 

The top of my craft has an octo RCS under the chute , then under the pod there is a service bay with 2 batteries and a mj bizzo. Under that is a KerbCan which is on top of a heat shield then a decoupler. You're absolutely correct I have gotten to orbit with about 300dV left in the terrier on one occasion but it wasn't enough to complete the rescue.

On an interesting side note I actually completed a rendezvous with a crew cabin (the plane looking one) and got the astronaut to it only to discover you can't enter that one from outside the ship. I tried for ages before reverting and switching to the kerbcan.

're: Scott Manley, the video I watched was titled 'gravity turn in the new aero 1.0.5' So not out of date at all.

[numerobis]

To get a Kerbal into the crew cabin, you need to (a) make your pilot EVA, (b) make your rescuee board the pod, (c) transfer crew from pod to crew cabin, (d) get your pilot back in. Somewhat annoying, but it works (my rescues have all been like that).

 

(c) and (d) are optional, of course. I did once get to orbit and realize that Bill was sitting in the rescue spot. Bill EVA'd and came back on a different rocket a few days later.

Edited January 8, 2016 by numerobis

[Plusck]

44 minutes ago, KerBlam said:

're: Scott Manley, the video I watched was titled 'gravity turn in the new aero 1.0.5' So not out of date at all.

Really? Wow, ok. I didn't think he'd made any KSP videos in the last year or so. My bad then.

[swjr-swis]

28 minutes ago, KerBlam said:

The top of my craft has an octo RCS under the chute , then under the pod there is a service bay with 2 batteries and a mj bizzo. Under that is a KerbCan which is on top of a heat shield then a decoupler. You're absolutely correct I have gotten to orbit with about 300dV left in the terrier on one occasion but it wasn't enough to complete the rescue.

On an interesting side note I actually completed a rendezvous with a crew cabin (the plane looking one) and got the astronaut to it only to discover you can't enter that one from outside the ship. I tried for ages before reverting and switching to the kerbcan.

I play only stock at the moment, so I can't replicate that specific build, but I had almost the entire upper stage of fuel left... not sure without MJ or KER or running numbers, but seems like it should have a good bit more than 300 dV left.

Another angle: the piddly what is it, 20 units of monoprop or so in the pod can run out really fast trying to rendevouz, even when one has experience with it. You might want to take advantage of the excess dV to lift an extra monoprop tank (perhaps a small one inside the service bay).

Another thought: moving the octo RCS from on top of the pod into the center node of the service bay. When you need RCS once in orbit, just open the bay. KSP doesn't care about part walls when it comes to RCS thrust, and it's one more bit of drag that would be removed on the way up through the atmosphere.

 

All that if you still want to tackle it with your own rocket (I admire persistence). But there's no shame in giving up on a design if it proves too troublesome for the task, sometimes it just works out that way. There's a couple of alternative and smaller rocket designs posted here that you might adapt for your needs. The achievement should not be any less for it, because sometimes the only right decision is going back to the drawing board.

Either way, you seem to be getting that much closer to rescuing those Kerbals, I'm sure you can do it! Remember to take a screenshot or two when it happens to share the triumph with us.

[Snark]

To echo what some folks have said earlier:  think small.

For example, there was some talk earlier in the thread about Kerbal Joint Reinforcement.  I would strongly recommend not using it, at least not until you've done a complete career play-through without it and have learned the ins and outs of the game.

I say this not because I'm some sort of hard-core realist (heck, I don't run FAR), but because you don't actually need KJR.  In fact, using it can actually make the game harder by masking symptoms of suboptimal design.

The fact is:  a "properly" designed rocket in KSP almost never needs KJR.  It's true that I don't make a habit of building 5,000-ton behemoths-- maybe if you like building ultra-large-scale, there would be a place for it.  But assuming you're not going totally off the deep end size-wise, you can build a ship that does just about any task you want, with very little in the way of wobble problems.

The fact that things get wobbly is good:  it's not trouble flying, it's a symptom that tells you "you're doing it wrong" and gives you a clue to try a different design. 

For example:  the design that you're having trouble with-- the real problem is not that the joints are wobbly.  Rather, the real problem is that it's massively overbuilt.  If all you need to do is get up to LKO with an empty crew slot or two, you have many times more rocket there than you need.  Instead of building up (and then having to strut everything, or use KJR, or whatever), build down.

For example:

There's a simple little ship that can rescue three kerbals from LKO.  Simple, cheap.  24 parts, 18 tons, nothing over tech 4.  Can get to 90 km circular orbit with 400 m/s of dV remaining.  Lifts off with the Hammers alone.  If you want a bit more oomph, you could add a second pair of Hammers, but honestly it doesn't need 'em.  Heck, if you drop the passenger cabin, it can take a single kerbal to a Mun flyby with 500 m/s of dV to spare!.

The real challenge in rocket design is how not to overbuild.  When you go out of balance-- i.e. have too much mass in the wrong place, or the wrong division of mass among stages, or whatever-- then things go bad fast.  And one significant symptom of "things are going bad" is when the rocket suddenly seems to be getting huge and wobbly.  That's the time to stop, re-evaluate, and try a different approach.  Just muscling through with KJR will ultimately hurt you, because you end up building a lot more rocket than you need and that costs cold hard cash.  Plus, you're eventually going to want to go beyond LKO, and that takes a lot more dV and is going to be a lot harder.  You really, really need to nail getting-to-LKO before you start going further, or you're going to run into lots of frustration.  LKO's a great training ground, and by forcing you to figure out how to make it work, it sets you up for success (and fun!) with the challenges that come next.

Anyway, just my two cents. 

Edited January 9, 2016 by Snark

[KerBlam]

3 hours ago, numerobis said:

To get a Kerbal into the crew cabin, you need to (a) make your pilot EVA, (b) make your rescuee board the pod, (c) transfer crew from pod to crew cabin, (d) get your pilot back in. Somewhat annoying, but it works (my rescues have all been like that).

That's good to know. If only I'd known that at the time XD

 

1 hour ago, Snark said:

The real challenge in rocket design is how not to overbuild.  When you go out of balance-- i.e. have too much mass in the wrong place, or the wrong division of mass among stages, or whatever-- then things go bad fast.  And one significant symptom of "things are going bad" is when the rocket suddenly seems to be getting huge and wobbly.  That's the time to stop, re-evaluate, and try a different approach.  Just muscling through with KJR will ultimately hurt you, because you end up building a lot more rocket than you need and that costs cold hard cash.  Plus, you're eventually going to want to go beyond LKO, and that takes a lot more dV and is going to be a lot harder.  You really, really need to nail getting-to-LKO before you start going further, or you're going to run into lots of frustration.  LKO's a great training ground, and by forcing you to figure out how to make it work, it sets you up for success (and fun!) with the challenges that come next.

Anyway, just my two cents. 

Your 2c is worth a buck oh five. I am definitely over engineering. I have a bit of time now so I'm going to do just that, re-evaluate and I'll post results. Hopefully positive ones and less frustrated and freaked out.

(I'm quitting nicotine as well, so it tends to make things feel a bit more visceral and I get hyped and want to swear at a big wobbly rocket instead of sensibly starting over.)

 

[KerBlam]

So I built down, and got some results. It was a pretty sloppy ascent on my first go ( a bit steep ) so I actually can't circularise with the dV I have, but I feel it's just tweaking from here and I will get there.

Thankyou very much everyone for all your help. I was starting to think that the early career was borked but it turns out that I am just crap at rocket design in the new aero. XD

Now to rescue these darned kerballs.

[swjr-swis]

4 minutes ago, KerBlam said:

it turns out that I am just crap at rocket design in the new aero. XD

Don't let the fact that someone made a game out of it fool you: it really still is actual rocket science! Buncha fancy-pants astronauts can make it seem easy sometimes, but they too had to work to overcome their instinctive surface-locked motion patterns and thinking, to learn to embrace the Dance of the Orbits and sing the Language of Physics. You have seen the Light!