Can't reach higher orbit

[miki1234]

Hi guys,

 

I have this nice rocket that can reach orbit pretty well. However I have a mission that requires me to go to 260K alt in orbit.. I cant seem to get enough fuel.

Do you have any recommendations / tutorials for me?

Plus is there any engineering mod that i can easily use to plan my rockets? Or tutorials? 

Thanks

[OHara]

You have a 1.8-meter decoupler between 1.25-meter parts, and that sticks out and makes a lot of drag that make it hard to steer.  There is a TD-12 that fits. (They all look the same, so sorting parts by size helps. Uninstalling Making History for a while will reduce the clutter of parts; you can go back and add it later.)

The radiator also gives drag fighting your steering, and does not help noticeably for re-entry heating.  Radiators route heat out of engines and internal equipment and slowly radiate the heat into space, whereas re-entry heating is relatively quick and heats the skin.   The winglets will help more if you slide them back toward the engine.

With these changes I think you will make the 260-km orbit with no problem.

Optionally, You can remove 3/4 of the ablator, or all of it if you like, and then the pod will slow down enough that you only need one parachute.   For the upper stage you can use a lighter-weight Terrier, if you've unlocked it.

[Kerbalstar]

31 minutes ago, miki1234 said:

Hi guys,

 

I have this nice rocket that can reach orbit pretty well. However I have a mission that requires me to go to 260K alt in orbit.. I cant seem to get enough fuel.

Do you have any recommendations / tutorials for me?

Plus is there any engineering mod that i can easily use to plan my rockets? Or tutorials? 

Thanks

I'm not at my KSP computer right now, but here's a few things to start:

1. A screenshot of your rocket would be really nice. You can take in-game screenshots using F1, and most people here on the forum use Imgur (just Google it). Imgur is free and does not require an account. To attach the pictures here, once they're fully uploaded, right click on the image and click "copy image address" , then just Ctrl+V it here. 
2. As for help, so you know how to get to a higher orbit? If not, here's how: Burn  at PE, until your AP is where you want it. Then time warp(.) to your AP and burn  there until your PE is at your desired altitude.
3. As for mods: Yes! Two great mods are KER (Kerbal Engineer Redux) and MJ (MechJeb). Those two mods give you a readout of something called DeltaV. That, combined with the "subway map" below, should be able to help you design your rocket.

The numbers these mods give you are the same as the ones listed on this map. You need to have approximately 3400m/sec to get to Low Kerbin Orbit(LKO), although in reality, it's a little more. You need about 1115 m/sec to get to KEO (stationary orbit above Kerbin), so I would pack about that much for your on-orbit stage, to have some margin. So total, I would suggest having 5115m/sec on your rocket, as given by those mods. Because I SO decreased in atmosphere, you might want a bit more. Hope this helped!

Merge: Pinging @Snark, because he really likes this kind of stuff!

[miki1234]

Hi thanks for all the help! I will now try to make some modifications.

This is my preview..

I know how to get to orbit, just to burn longer at apoapsis.. I couldn't find the fuel.

Do you think i need to add more solid fuels?

 

5 hours ago, OHara said:

Optionally, You can remove 3/4 of the ablator, or all of it if you like, and then the pod will slow down enough that you only need one parachute.   For the upper stage you can use a lighter-weight Terrier, if you've unlocked it.

What does this save? Weight? 

[Xd the great]

30 minutes ago, miki1234 said:

Hi thanks for all the help! I will now try to make some modifications.

This is my preview..

I know how to get to orbit, just to burn longer at apoapsis.. I couldn't find the fuel.

Do you think i need to add more solid fuels?

 

What does this save? Weight? 

Yes, it saves weight.

And MOAR boosters will help.

Preferably remove the radiators. You can enter at 40km PE from a 260k orbit, and save some more mass.

Do you know about gravity turns?

[miki1234]

I now reached orbit and it's still not optilal

 

 

Gravity turns - Can you be more specific? What are MOAR boosters? 

 

[Harry Rhodan]

23 minutes ago, miki1234 said:

I now reached orbit

That contract wants you to stay sub-orbital and not go into an orbit.

[Pecan]

1 hour ago, miki1234 said:

I now reached orbit and it's still not optilal

 

 

Gravity turns - Can you be more specific? What are MOAR boosters? 

 

Welcome, congratulations and well done.  You have taken the advice here, including posting pictures, really well and the willingness and sense to learn will make everything else in KSP a lot easier than for a lot of people :-)

As Harry Rhodan said above, however, the contract needs you to be sub-orbital so getting into 270+km orbit was actually a much harder task than you need.  To complete this contract you just need a much smaller/cheaper/easier vehicle that can go straight up to a maximum of 280km.  Then do the engine test somewhere between 270km and 280km, either on the way up or the way down.  Also note that you don't need the vehicle to be crewed so you could make it even cheaper and lighter by using a disposable probe core, if you have any unlocked.

("Gravity Turn" - this is gradually turning to a more horizontal flightpath as you ascend.  Much more efficient way to achieve orbit than 'getting height then trying to get horizontal speed.  Normally the No.1 thing to learn about getting into orbit but irrelevant in this case, which is only about getting to space not to orbit.

"MOAR boosters" is an in-joke that "more boosters" is the brute-force solution usually suggested by those who don't really know what they're doing, or how to spell it.  Don't worry, there's no secret boosters by MOAR that you've missed *grin*.  In general more boosters will work but we all like to find a more elegant solution if we can.)

Edited December 12, 2018 by Pecan

[Pecan]

By the way - if you have the Stayputnik unlocked the cheapest/lowest tech vehicle for this mission that I have found is:

Stayputnik <- probe core
Small inline reaction wheel <- without this it has no steering and just tumbles
z-100 battery <- or the vehicle dies before it reaches the required altitude, so you can't do the test
FL-T200 fuel tank <- T100 isn't enough but see note below
Terrier engine <- which is what you have to test, of course!
TD-12 decoupler
Hammer <- thrust-limited to 40% otherwise it accelerates too fast too early
3x basic fins <- for stability

Cost 2,520 funds.
Note: This actually reaches over 600km so you don't need all the fuel in the T200 tank.

[Kryxal]

I was going to suggest getting to 270 km before raising your periapsis out of atmosphere even before noticing that the contract calls for suborbital.  The radiator's pretty useless, the parachutes on the lower stage probably aren't worth the bother, and KER or MechJeb's delta-v readout might be nice, but if you can hit orbit as-is, a few tweak should get you there.

Oh, and people are right about the decoupler, use the right size.

[miki1234]

5 hours ago, Pecan said:

By the way - if you have the Stayputnik unlocked the cheapest/lowest tech vehicle for this mission that I have found is:

Stayputnik <- probe core
Small inline reaction wheel <- without this it has no steering and just tumbles
z-100 battery <- or the vehicle dies before it reaches the required altitude, so you can't do the test
FL-T200 fuel tank <- T100 isn't enough but see note below
Terrier engine <- which is what you have to test, of course!
TD-12 decoupler
Hammer <- thrust-limited to 40% otherwise it accelerates too fast too early
3x basic fins <- for stability

Cost 2,520 funds.
Note: This actually reaches over 600km so you don't need all the fuel in the T200 tank.

This sounds super interesting!!! I will try and call it cheap sub orbital.

 

This is my newer rocket flies way smoother 

 

 

Thx everybody!!

[Xd the great]

9 hours ago, miki1234 said:

I now reached orbit and it's still not optilal

 

 

Gravity turns - Can you be more specific? What are MOAR boosters? 

 

In short, go straight up. Just up.

[Pecan]

2 hours ago, miki1234 said:

Thx everybody!!

You're welcome.  Sensible questions deserve sensible answers and the only stupid question is the one you didn't bother to ask.
Really - we all remember trouble with the most basic situations and the community here is one of the best.
Next up; "now you're an addict, how to help everyone else".

[miki1234]

Hi to conclude I have two potential rockets for orbit as ive been able to accomplish this a few times. 

A main problem now is that i have to carry two astronauts for science reports or missions, and i can't seem to get my re reentry speed low. I tried to Make a more elegent design but it seems somehow i get left witouht enough oxidizer.

You can look at both "designs", I would love your opinions

 

 

 

[dave1904]

In my opinion your top stages are to heavy compared to your bottom ones. I tend to build craft with a 1st stage delta v of about 2500-3000(overkill but easy). Just try building a 1 man pod, a heat shield, 1 small tank and a small engine since upper stages dont need alot of trust.  Keep in mind engine that a lower engine mass is better than a higher isp for smaller upper stages with small amounts of fuel.  Then add a larger bottom stage. This might not get you to higher orbit but it will show you that less complex rockets do the job too. Your first rocket (1 man pod)is designed like that and I assume its far better to launch. Looking at the parts you're using I would assume you have not unlocked better solid rocket motors so your goal should be to get more science and ignore getting 2 people to orbit until you have better parts for more crew. As Xd the great pointed out you really just need to lauch your rocket straight up anyway since you don't need an orbit for your contract. You should have more than enough delta v for that. 

[Curveball Anders]

47 minutes ago, dave1904 said:

In my opinion your top stages are to heavy compared to your bottom ones. I tend to build craft with a 1st stage delta v of about 2500-3000(overkill but easy).

I usually design the upper stage (or payload) to do it's job just shy of orbit, then I design a lifter that burns out just before achieving orbit.

[dave1904]

2 minutes ago, Curveball Anders said:

I usually design the upper stage (or payload) to do it's job just shy of orbit, then I design a lifter that burns out just before achieving orbit.

yup best design imo. 

[miki1234]

Thx for all the replies. I think i need a little bit more science to reach a two person module. Any insights on easy ways to get science ? I haven't build a proper airplane yet..

 

[bewing]

Either build a proper airplane for the first time and explore Kerbin's surface, or build a little rover and explore the KSC campus (IIRC there are 31 minibiomes on the KSC campus that all give science points -- it takes an hour to gather them all but it's worth hundreds of points), or do a low flyby of the Mun (below 60km). A low Mun flyby works best if you've upgraded the Astronaut Complex once, so that you can EVA over each Munar biome.

Edited December 16, 2018 by bewing

[miki1234]

This is my older desgn

 

Now that ive gotten the two people pod i tried to make something like this but it's incredibly unstable to fly

Can someone explain?

 

[bewing]

1 hour ago, miki1234 said:

but it's incredibly unstable to fly

Can someone explain?

Two reasons: the vostok pods are bigger than the MK1 pods, and probably have more drag. So you are increasing the drag at the front end of your rocket -- and high drag at the front end makes your rocket unstable.

Additionally, one of the things that makes the MK1 design easier to fly is that it has a built-in "reaction wheel". Reaction wheels increase the amount of steering forces your rocket has available. We call it "control authority". Vostok pods do not have any built-in reaction wheels. To fly a vostok-based design, you either need RCS thrusters (which you need to unlock on your tech tree), or you need to add a reaction wheel.

 

 

[miki1234]

Thx. I think I dont have big enough reaction wheels..

 

[Loren Pechtel]

On 12/12/2018 at 8:53 AM, Kryxal said:

I was going to suggest getting to 270 km before raising your periapsis out of atmosphere even before noticing that the contract calls for suborbital.  The radiator's pretty useless, the parachutes on the lower stage probably aren't worth the bother, and KER or MechJeb's delta-v readout might be nice, but if you can hit orbit as-is, a few tweak should get you there.

Oh, and people are right about the decoupler, use the right size.

I play with Stage Recovery (a mod that recovers dropped parts when they go out of physics range if they come down gently enough) and chutes are basically never worth it on 1.25m parts--you'll spend more on chutes than you'll get back when you recover the booster unless it drops very close to the launch site.  Chutes only for things you actually need to recover--Kerbals and science.