Launching a 44t payload

[Anonymous49]

what about 2000m

[dave1904]

2 hours ago, Anonymous49 said:

i'm trying

resilient is sitting on the pad right now

T-13 minutes

T-5 minutes

and liftoff

still flipped

this time im trying 6 tall fins

still not working

12 still doesn't work

I can't help right now but if you're still having issues in 12 hours you can upload the craft file and I'll take a look. 

[Anonymous49]

OK

[KawaiiLucy]

You only need 3600 m/s of dv to reach orbit, and that is with a a margin. I usually design a auncher in three stages if you want to rendez-vous, Lower Stage with 2600 m/s dv for ascent, upper stage with 1500 m/s of vaccuum dv and then if you want to rendez-vous one stage with 1000 m/s dv, which is overkill, but gives you an error margin. If you tip over, ascend straight up and initiate a gravity turn at about 12 km to 20km. It doesn't hurt that much to have a slighlty inefficient launch trajectory.

[Incarnation of Chaos]

That....

That won't make orbit in one piece

Those small joints between the 1st stage and the Second are going to come undone and cause weirdness before you stage off, the flexion introduced is what's likely causing your erroneous angle of attack due to aero surfaces not correcting it.  You can use brute force, and lash  it together with struts.  Not the way you've done it however, you need three sets of struts. One from the SRBs with radial symmetry, connected to the tip of the cones to as far up the second stage tankage as possible. Second set of smaller ones,  8 with radial symmetry between that first and second stage joint to further stabilize it. And the third from the second stage to the beginning of the fairing at the top.

But the much better option is just a complete refactor, getting a TWR of 1.2 with a 44T payload with a Two-Stage to Orbit rocket isn't that difficult.

And can be done very cheaply.

But that's assuming you have the right parts, which basically means I'm asking if you have 2.5 M tanks, and fuel lines. Mastadon Engine is also a lifesaver, but not absolutely required.

[Anonymous49]

27 minutes ago, Incarnation of Chaos said:

That....

That won't make orbit in one piece

Those small joints between the 1st stage and the Second are going to come undone and cause weirdness before you stage off, the flexion introduced is what's likely causing your erroneous angle of attack due to aero surfaces not correcting it.  You can use brute force, and lash  it together with struts.  Not the way you've done it however, you need three sets of struts. One from the SRBs with radial symmetry, connected to the tip of the cones to as far up the second stage tankage as possible. Second set of smaller ones,  8 with radial symmetry between that first and second stage joint to further stabilize it. And the third from the second stage to the beginning of the fairing at the top.

But the much better option is just a complete refactor, getting a TWR of 1.2 with a 44T payload with a Two-Stage to Orbit rocket isn't that difficult.

And can be done very cheaply.

But that's assuming you have the right parts, which basically means I'm asking if you have 2.5 M tanks, and fuel lines. Mastadon Engine is also a lifesaver, but not absolutely required.

i thought i said i hate solids

[Gargamel]

2 hours ago, Anonymous49 said:

i thought i said i hate solids

Really doesn’t matter if you hate them, in the current versions of KSP, they’re what works.   Now, if you’re refusing to use them, for some odd reason, then we’ll help you design around that.    
 

Sounds like you need some asparagus      

[Guest]

Yeah man, you're overengineering and it's causing you all kinds of mayhem. Time to go back to the drawing board. Don't sweat it, going back to the drawing board pretty much is the entire game.

Start with the payload. Package it. Then build a rocket under it. Aim for 3600 m/s vacuum dV, 1.2 atmospheric TWR on the launchpad, and don't have the TWR drop below 1 until you get to orbital insertion. Keep it as simple as you can – one core stack with 1-2 stages plus the payload, and 2-6 boosters strapped radially to it. Autostrut the boosters to grandparent part so they don't wobble. You can use LF boosters if you don't like solids, Reliants + 1.25 tanks make for very good (and reasonably cheap) early-ish career LF boosters. Then when you launch it, start your gravity turn at around 70 m/s so you're pointed at 80 degrees when you hit 100 m/s, 45 degrees when you hit 10 km, then watch your Ap, keeping it about 1 min away until you're ready for insertion; if you start closing in on it aim up a little.

Your payload is pretty hefty but it shouldn't be that hard. 

[dave1904]

3 hours ago, Anonymous49 said:

i thought i said i hate solids

I got home earlier. Upload a link of the craft file somewhere and I will take a look. I would still recommend you figure out how to do this yourself anyway because you will learn. 

[paul_c]

First thing is (and its already been mentioned), you have a bunch of decouplers firing on your first stage. Why? This will just blow apart the rocket on the pad? The only thing that should decouple on launch are the launch stability arms, although you don't really need them for a wide-at-the-base rocket in KSP.

Secondly, regarding SRBs. You can do the job of a SRB (ie initial heavy lift of 1st stage from ground to ~10000m) using liquid fuel/engines if you want, but it will just cost more. Look at the "price per thrust" or something like that, once you've added in the fuel tanks etc. Sometimes I've done liquid 1st if its going a bit higher (so I get the controllability). One/some of the larger SRBs can gimbal though but I can't remember which one.

Thirdly, as others have mentioned, I've found the best approach is to make a payload, then add a final stage underneath it, then (eg) 2nd stage, then (eg) 1st stage. That way, you can even dedicate/tune each stage for its purpose, for example if the final stage is simply to reposition in a higher orbit, it doesn't need big engines and you can save weight. For every 1kg you save in an upper stage, you save 10 times that (or more, maybe even 20 times) in the lower stages. So you can see how using an engine weighing 130kg is MUCH better than an engine weighing 1.5t.

If its flipping/crashing at 2000m there is something fundamentally wrong with the design. So feel free to scrap it and start from the beginning on this one!

[Incarnation of Chaos]

5 hours ago, Anonymous49 said:

i thought i said i hate solids

Sorry, I misspoke. Should have just said "Boosters" instead of SRBs specifically, there's nothing wrong with making a liquid fueled asparagus 1st stage.

[Anonymous49]

13 minutes ago, Incarnation of Chaos said:

Sorry, I misspoke. Should have just said "Boosters" instead of SRBs specifically, there's nothing wrong with making a liquid fueled asparagus 1st stage.

i use a lot of liquids

1 hour ago, paul_c said:

First thing is (and its already been mentioned), you have a bunch of decouplers firing on your first stage. Why? This will just blow apart the rocket on the pad? The only thing that should decouple on launch are the launch stability arms, although you don't really need them for a wide-at-the-base rocket in KSP.

Secondly, regarding SRBs. You can do the job of a SRB (ie initial heavy lift of 1st stage from ground to ~10000m) using liquid fuel/engines if you want, but it will just cost more. Look at the "price per thrust" or something like that, once you've added in the fuel tanks etc. Sometimes I've done liquid 1st if its going a bit higher (so I get the controllability). One/some of the larger SRBs can gimbal though but I can't remember which one.

Thirdly, as others have mentioned, I've found the best approach is to make a payload, then add a final stage underneath it, then (eg) 2nd stage, then (eg) 1st stage. That way, you can even dedicate/tune each stage for its purpose, for example if the final stage is simply to reposition in a higher orbit, it doesn't need big engines and you can save weight. For every 1kg you save in an upper stage, you save 10 times that (or more, maybe even 20 times) in the lower stages. So you can see how using an engine weighing 130kg is MUCH better than an engine weighing 1.5t.

If its flipping/crashing at 2000m there is something fundamentally wrong with the design. So feel free to scrap it and start from the beginning on this one!

those are first stage engine plates. They are useless as there are nothing on the bottom so I thought that it could give some force for liftoff (though only a small amount but it is still a bit)

2 hours ago, dave1904 said:

I got home earlier. Upload a link of the craft file somewhere and I will take a look. I would still recommend you figure out how to do this yourself anyway because you will learn. 

maybe tomorrow it is almost 9pm

[paul_c]

I don't know what a "first stage engine plate" is but KSP doesn't need them. Just attach side boosters using the radial decoupler and get it ever-so-slightly above the middle, so it ejects them clear of the vehicle.

If you're JUST using them for more force, its not going to make any difference on 44t. They do, marginally, in eg Minmus orbit. At an advanced level you can decouple at the right time in the right direction (eg during a small satellite launch) to get a little benefit rather than an inconvenience. But for now, forget about them, they're just adding complexity in the staging etc. This will also be why your fairing is exploding - if you decouple something within the fairing, it will destroy it. Take time to get the exact details of staging right in the VAB so its easy to do it once its flying.

[Anonymous49]

7 minutes ago, paul_c said:

I don't know what a "first stage engine plate" is but KSP doesn't need them. Just attach side boosters using the radial decoupler and get it ever-so-slightly above the middle, so it ejects them clear of the vehicle.

If you're JUST using them for more force, its not going to make any difference on 44t. They do, marginally, in eg Minmus orbit. At an advanced level you can decouple at the right time in the right direction (eg during a small satellite launch) to get a little benefit rather than an inconvenience. But for now, forget about them, they're just adding complexity in the staging etc. This will also be why your fairing is exploding - if you decouple something within the fairing, it will destroy it. Take time to get the exact details of staging right in the VAB so its easy to do it once its flying.

i had engine plates on the first stage and they act like decouplers

if i didn't have engine plates i could not place 23 skipper engines on the first stage

[Gargamel]

2 minutes ago, Anonymous49 said:

if i didn't have engine plates i could not place 23 skipper engines on the first stage

Engine plates are a relatively new addition to the game, and yes, we added oodles of engines without them.   Plates just make it cleaner. 

[paul_c]

The mind boggles!

Delete the entire rocket (keep the payload), do the last stage and show a screenshot. As a ROUGH guideline I would recommend the staging like this (doesn't matter what the payload is):

First stage: 1000m/s, TWR ~1.3-1.5
Second stage: 2000m/s, TWR 1.2
Third stage: 1000-1500m/s TWR 0.5

This gives plenty to get to orbit, do some orbital adjustments for rendezvous and a bit of margin too. For now, concentrate on getting 3 stages nicely flyable.

Edited February 8, 2021 by paul_c

[VoidSquid]

1 minute ago, Gargamel said:

oodles

Totally unrelated to the topic, but what in <insert deity of your choice>'s name are oodles???

[Gargamel]

Just now, VoidSquid said:

Totally unrelated to the topic, but what in <insert deity of your choice>'s name are oodles???

oodles of noodles.    oodles = lots. 

[VoidSquid]

Never heard that, thanks! So the forum also provides some teaching of unusual English words (recently learned "curmudgeon" from Snark), hehe  

[VoidSquid]

30 minutes ago, paul_c said:

First stage: 1000m/s, TWR ~1.3-1.5
Second stage: 2000m/s, TWR 1.2
Third stage: 1000-1500m/s TWR 0.5

This!

My preferred numbers are almost identically, for the 1st stage I usually use SRBs only (save for heavy payload over approx. 150 tons).

Why SRBs only you may ask: SRBs, in the last say 30s of burn, provide an immense thrust. I try to reach about 12 km altitude with the the 1st stage, and about 450 m/s vertical speed. 2nd LfOx stage then can go with the much lower TWR of mentioned 1.2., no need for overall expensive and heavy engines.

Edited February 8, 2021 by VoidSquid

[Guest]

FYI I built a 45-ton lifter using more or less the tech and parts you had. Liquid only cost about 70 k (excluding payload and fairing). Replacing the LF boosters with Kickbacks knocked about 9k off the price. 

Spoiler

I used a 2.5 m core with two Skippers, and four 1.875 m boosters, also with Skippers, for the liquid-only solution. Replaced the boosters with Kickbacks and added more fuel to the central stack for the solid-boosted variant. Did not use an insertion stage. I didn't know if you have Making History; if you do, I would have replaced the Skippers with cheaper parts from there and saved a fair bit more.

 

[Spricigo]

 

If you want a craft that put 45t in orbit with 975m/s deltaV left for half the price tag, Sturdy is up to the task.  

 

Now, back to your situation: the craft in the picture have way more than enough deltaV and TWR to get into orbit and you are using  MJ to handle the piloting.  The only explanation: there is a saboteur messing with your craft and making it fail. Ok, ignore the joke. But yes, you craft is overpowered* not underpowered, and using an autopilot is unlike to be a problem with the trajectory.

As you describe it seems the engines in the later stage are not producing (enough) thrust. The image show you have some engines inside a fairing , in this case they will not produce any trust, sometimes, because a bug, even after you deploy the fairing.

 

*The idea is to have a craft that have just enough for the task at hand. When designing a rocket try to also pay attention to what is better to not have in the craft. Saving fund and, more important, mass comes with big benefits.

[Anonymous49]

i prefer LF's because they burn longer. My explorer sets of boosters burn over 2 minutes

13 hours ago, Gargamel said:

Engine plates are a relatively new addition to the game, and yes, we added oodles of engines without them.   Plates just make it cleaner. 

how to do that? The only thing I can think of that doesn't need engines are radial ones. But the maximum is the thud only. I don't have those structural adapters yet

10 hours ago, Spricigo said:

 

If you want a craft that put 45t in orbit with 975m/s deltaV left for half the price tag, Sturdy is up to the task.  

 

Now, back to your situation: the craft in the picture have way more than enough deltaV and TWR to get into orbit and you are using  MJ to handle the piloting.  The only explanation: there is a saboteur messing with your craft and making it fail. Ok, ignore the joke. But yes, you craft is overpowered* not underpowered, and using an autopilot is unlike to be a problem with the trajectory.

As you describe it seems the engines in the later stage are not producing (enough) thrust. The image show you have some engines inside a fairing , in this case they will not produce any trust, sometimes, because a bug, even after you deploy the fairing.

 

*The idea is to have a craft that have just enough for the task at hand. When designing a rocket try to also pay attention to what is better to not have in the craft. Saving fund and, more important, mass comes with big benefits.

23 skippers in the first stage

2 in the second stage

1 in the payload (which is the module)

at liftoff the twr is 3.5, during staging the first stage has a twr of 6. The second stage starts of with a twr of around 2. But the payload would go through the fairing during the gravity turn

this is the new one

the old one has a similar first stage with also 23 engines but the boosters (which have 3 each) would stage 2 by 2 until all 6 go away. That's the problem.

[Anonymous49]

seems good i have everything needed but if ur asking this is how big the 44t module (which includes fairing) isthis large

[Spricigo]

 

 

2 hours ago, Anonymous49 said:

seems good i have everything needed but if ur asking this is how big the 44t module (which includes fairing) is

[snip]

this large

Increase the fairing as necessary. As long the craft remain stable, is not difficult to figure out the adjustment to the trajectory (if any needed).