Launching a 44t payload

[Anonymous49]

ok

[Guest]

On 2/8/2021 at 3:58 AM, Anonymous49 said:

IT'S 44 TONNES MAN

23 SKIPpeR ENGineS

I built a 45-ton launcher and I only used 6 Skippers in the entire rocket. You need to redesign.

Edited February 9, 2021 by Guest

[VoidSquid]

My 45 tons lifter quick test build has 6 Kickbacks (1st stage) and 1 Mainsail (2nd stage).

  What @Brikoleur said:

51 minutes ago, Brikoleur said:

You need to redesign.

 

Edited February 9, 2021 by VoidSquid

[Guest]

2 minutes ago, VoidSquid said:

My 45 tons lifter quick test build has 6 Kickbacks (1st stage) and 1 Mainsail (2nd stage).

 

I'm not sure he has the Mainsail yet, and he said he doesn't want to used solid fuel boosters, so I just powered the entire thing with Skippers.

Replacing the Skipper-LF-boosters with Kickbacks saved about 9k off the price, so 4 Kickbacks + 2 Skippers got the job done too for a bit cheaper.

I understood from another message that OP doesn't like solid fuel boosters because they burn too fast. Hey @Anonymous49, have you noticed that you can set a thrust limiter on the SRBs so they burn longer at lower thrust? Really, the simplest and cheapest solution for this kind of thing is a liquid core with 2-6 SRBs strapped onto it, with maybe an upper stage on top of the core, depending on what engines you have available in your tech tree.

[VoidSquid]

3 minutes ago, Brikoleur said:

I understood from another message that OP doesn't like solid fuel boosters because they burn too fast

Yes, I did read that too. The argument "burn time" is not an argument at all here though imo, the only two parameters of interest in this context are TWR and dv (plus maybe costs).

Edited February 9, 2021 by VoidSquid

[Anonymous49]

another problem is i cannot use asparagus staging for it, i cannot reignite it, i cannot extend it

plus i don't have the mainsail yet it is a level 6 node

[VoidSquid]

51 minutes ago, Anonymous49 said:

i cannot use asparagus staging for it

Imo asparagus staging is way overvalued, for a mere 45 tons lifter there is no need to use that. In fact, I recommend not to use it here.

Spoiler

What @paul_c said: "Asparagus staging is interesting and can be made to be efficient"

"can be made to be efficient" - that actually requires a bit tinkering, you don't want the stages to burn up too fast, nor too slow, but maintain a good TWR at all times.

 

51 minutes ago, Anonymous49 said:

i cannot reignite it

What exactly you can not reignite? 

51 minutes ago, Anonymous49 said:

i cannot extend it

What exactly you want to extend?

51 minutes ago, Anonymous49 said:

plus i don't have the mainsail yet

You can use 2 Skippers instead, as @Brikoleur suggested.

Edited February 9, 2021 by VoidSquid

[Guest]

21 minutes ago, Anonymous49 said:

another problem is i cannot use asparagus staging for it, i cannot reignite it, i cannot extend it

Look, don't make this more complicated than it is.

Just build a core powered by two Skippers, strap 4-6 boosters of your choice to it, aim for 3600 m/s vacuum dV and 1.2-1.5 atmospheric TWR on the launchpad, making sure that TWR stays above 1 at all times. You will be able to do this with 6 Skippers total, or 2 Skippers and 4-6 Kickbacks, or a similar number of a mix of other engines. It shouldn't cost you more than 60-70 grand not including the payload. 

[Spricigo]

So, you have the good advice from @Brikoleur and @VoidSquid if you want to build a reasonable craft. Or you can use my not so reasonable(but functional) craft you already downloaded.

I don't see any reason to not have this station of you in orbit yet if that is your goal.

 

 

 

 

 

 

Edited February 9, 2021 by Spricigo

[paul_c]

Asparagus staging is interesting and can be made to be efficient but for now, keep it simple:

3 Stages
1st stage using SRBs and does 1000m/s

For SRBs there are 2 parameters you can change - the amount of fuel; and thrust. These change the deltaV and TWR respectively. You can literally (in the VAB) "tune" the SRB performance to exactly what you want it to be. 

[alphaprior]

I always have problem to launch heavy loads. What I do is to try and make them lighter like seperate launces instead of a single one.
If that's not possible then I have to be more creative by rejecting weight as I go higher. For example instead of using 6 radial tanks I use 2+2+2 connected with fuel ducts. 
Connection is like this Tank A > Tank B >Tank C. So the tank A empties gets rejected then B and finally C.
Under the liquid fuel tanks I used solid boosters which were the first to reject and I already had a good speed.

It's a very efficient way to launch, I used this method for Eve launch and worked perfectly.
Why do you hate solids? They are essential to heavy launches especially one like yours.

Edited February 9, 2021 by alphaprior

[Anonymous49]

10 hours ago, alphaprior said:

I always have problem to launch heavy loads. What I do is to try and make them lighter like seperate launces instead of a single one.
If that's not possible then I have to be more creative by rejecting weight as I go higher. For example instead of using 6 radial tanks I use 2+2+2 connected with fuel ducts. 
Connection is like this Tank A > Tank B >Tank C. So the tank A empties gets rejected then B and finally C.
Under the liquid fuel tanks I used solid boosters which were the first to reject and I already had a good speed.

It's a very efficient way to launch, I used this method for Eve launch and worked perfectly.
Why do you hate solids? They are essential to heavy launches especially one like yours.

cannot shut down, like i they burn up their fuel when my apogee is something like 150km. 

u know what u said was asparagus staging, which was my original idea

[Spricigo]

13 minutes ago, Anonymous49 said:

cannot shut down, like i they burn up their fuel when my apogee is something like 150km. 

 There is something preventing you from having fewer boosters in your craft?

[Anonymous49]

1 minute ago, Spricigo said:

 There is something preventing you from having fewer boosters in your craft?

taking about srb's

[Spricigo]

Just now, Anonymous49 said:

taking about srb's

You didn't answered the question. Are you really interested in help or what?

[VoidSquid]

24 minutes ago, Anonymous49 said:

cannot shut down, like i they burn up their fuel when my apogee is something like 150km. 

That's why we suggested you use SRBs for the first stage only, with 1000-1200 m/s dv. That will bring your rocket to about 12 km altitude, with an Ap of less than 20 km, not 150 km  

[Anonymous49]

a few thumpers usually bring me over 100km. A command pod with a thumper goes over 100km

[VoidSquid]

A Mk1 pod with chute, heatshield, decoupler, thumper has a vac. dv of 2477 m/s, way below the 3400 required for reaching orbit. 

Maybe you didn't do the gravity turn ?

[Anonymous49]

no heat shield and im saying  suborbital

[VoidSquid]

Just now, Anonymous49 said:

no heat shield

2600 m/s then, doesn't change anything.

Just now, Anonymous49 said:

and im saying  suborbital

Even with 2600 m/s from SRBs, your craft can't reach orbit. And we were suggesting to have 1000-1200 m/s for the first SRB based stage. The only way you can reach such a high Ap of 100+ km is that you're not doing a proper gravity turn.

[Hotel26]

Quote

taking about srb's

I have never used SRBs in my life.  Call me "close minded"...  (It's probably because I am a "sandboxer" and religiously don't give a fig about cost.)

Then lately I stole an idea from a recent suggestion by Corona688 -- an idea that turned out to be a Great Idea -- and produced a brilliant little 20t$$ lifter, based on Stage 1 SRBs.  What an eye opener?!

Gee, I wish I wasn't so stubbornly stupid...  I guess I am a "Contrarian".  I love to argue with people who are trying to help me, I suppose.  What a loser I can be!  Maybe the only people stupider than me are those trying to help me??

And yet, KSP is fundamentally always about the design challenge.  And so, coping with real limitations and making rational decisions to achieve some optimum is key in the process -- and the ultimate source of triumph.  (Late realization, from a slow starter...)

Edited February 10, 2021 by Hotel26

[Anonymous49]

i always use my traditional way it usually go beyond sometimes though

[VoidSquid]

@Hotel26 The main reason I'm most often using a SRB-only 1st stage:

  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. Which translates to cheaper rockets / more payload  

 

[Hotel26]

Just now, VoidSquid said:

in the last say 30s of burn

Have we mentioned already the intense pleasure incurred in Mission Control by that absolutely awesome universe-splitting display of Raw Power that SRBs give...?

"Moaaah tail fins."

[VoidSquid]

1 minute ago, Hotel26 said:

"Moaaah tail fins."

Very true, yes  

Hence, in career mode, I only start using SRBs when the good AV-R8 fins become available.