Orange tank ssto?

[Cloakedwand72]

How do I make a orange tank ssto that can get a low stable orbit with enough delta v to dock to a station and fly back down?

[Tecorian]

Hmmm... do you mean these tanks, which we common know from the space Shuttle?

I think, these are indended to get rid of them after launch.

If you mean, building a STTO with mostly @stock-parts, have a look on my "standard-ssto"

I simply attached two big tanks on each side of the wings and use only a rocket motor for propulsion.

Not like the common sstos with partly airbreathing engines, you have to gain very quickly height above sea level.

I use a LFO engine from a mod, somekind realistic for KSP 1 (not for the real world) with a thrust of 1.500 and an isp of 315

dockingport is in the nose of my shuttle

Initially, i have LFO for about 5.000 m/s onboard, in a low orbit of about 80.000 m will have  still have about 450-475 m/s in reserve, enough for all manouvers in orbit around Kerbin

And yes, its possible to paint these tanks also in orange

 

 

Edited June 14, 2024 by Tecorian

[king of nowhere]

2 hours ago, Cloakedwand72 said:

How do I make a orange tank ssto that can get a low stable orbit with enough delta v to dock to a station and fly back down?

ssto is a very generic term, and so are your requirements.

if by "orange tank" you mean the 36 tons one, just strapping a skipper engine underneath should give you over 4000 m/s, enough to orbit with some spare for docking.

if you want a spaceplane, you make it like you'd make any other spaceplane... i don't understand the question, really.

[Vanamonde]

8 hours ago, Cloakedwand72 said:

How do I make a orange tank ssto that can get a low stable orbit with enough delta v to dock to a station and fly back down?

I wish I knew. I failed many times and only succeeded once, largely by luck. 

[Lt_Duckweed]

@Tecorian @king of nowhere

"Orange Tank SSTO" is somewhat more rare nowadays but used to be common shorthand for an SSTO that can take a 36 ton Jumbo-64 tank to orbit as payload.

On 6/14/2024 at 2:50 AM, Cloakedwand72 said:

How do I make a orange tank ssto that can get a low stable orbit with enough delta v to dock to a station and fly back down?

The key for SSTO spaceplanes is:

1. Reduce drag.  Make sure any rcs, solar panels, radiators, etc are stuffed inside a payload or cargo bay, and only open it up once in space.  Make sure you don't have any flat blunt surfaces with open attachment nodes facing directly into or away from the airstream (you need to cap the node with a part which approximately matches the size of the flat surface (example: 1.25m nosecone on the front of a 2.5m tank won't help much.  Use a 2.5m nosecone).  If you want to get fancy, try using "Wing Incidence" to build in the angle of attack on your wings.  Wings in KSP need some angle of attack to generate lift, but fuselage parts with an angle of attack generate lots and lots of drag, so you want the body pointing prograde and the wings angled up so that you can get lots of lift from them.
2. Proper ascent is very important.  Engines are heavy, so you want as few as you can get away with, so you want to add just enough rapiers to take off by the end of the runway (even if that is done by literally falling off the end of the runway), and punch through the speed of sound.  If your rapiers can get you to at least ~450m/s at sea level, you are good to go for the rest of the flight.  Once you reach ~450m/s at sea level, you want to slowly start ascending, gently nosing up over ~30 seconds  up to an angle of around 20-25 degrees.   Hold this until you are getting close to 10km altitude, then begin leveling off very slowly.  The ideal goal is to hit 18-20km at the same time as you hit around 1400-1500 m/s and finish leveling out.  The goal now is to very slowly climb to around 21-22km while you finish gaining all the speed you can on rapier jet mode.  You want to get to at least 1600m/s, even better if you can get over 1650m/s or even 1675m/s.  Then, you want to turn on your nervs (if you have them) and swap the rapiers into closed cycle rocket mode (if you have oxidizer).  You don't really need to pull up here other than a tiny handful of degrees.  Your sheer speed and you approach orbital velocity will naturally push your apoapsis out of the atmosphere and raise your nose.  Then you just coast your apoapsis and perform a small circularization burn to enter orbit.

Some further tips:

1. It may be that the above ascent profile makes you explode from overheating.  Generally this is due to one of two things:  either you have too much twr and accelerated too fast at too low an altitude, or you didn't use heat resistant parts.  Ideally you redesign for lower twr (since that means less dry mass and thus more dv) or use more heat resistant parts in the areas that were most vulnerable.
2. Generally, some good benchmark numbers when starting out are that you should aim for at least 20-25 tons of mass on the runway per rapier engine, and 1 wing area per 4-6 tons of mass on the runway (you can see wing area of a wing part by right clicking it in the part selection menu on the left in the VAB).  The engine number can comfortably be pushed above 30, even to 36tons, when you are quite practiced at building efficient craft, and experts can go even higher than that when taking off from the flat area around the KSC instead of the runway, but 20-25 is good to start.

As for designing a craft specifically for hauling an orange tank, you have to make a decision early on: will you use a fairing open at one end, or a Mk3 bay, to carry the fuel tank?  Using a fairing is a lot lighter, but requires more expertise to build an effective plane, so we can throw that aside for now.  You will need a long MK3 bay to hold the tank, and you can probably also squeeze in a reaction wheel, batteries, and solar panels in it on one end.  If you don't want the craft to be crewed, we also need a probe core of some kind.  We can probably target a total mass of the craft of 120 tons to start, so we will need around 5-6 rapiers, and 20 to 30 total wing area.  One of the best wings for the job is the big s wing.  It comes with free liquid fuel storage of 300 units in each wing, which saves on tanks, and has a wing area of 5, so you need 2-3 pairs of them.  Then we add control surfaces, landing gear, and any other goodies you want.   Lastly, we want to pack any remaining mass budget with fuel tanks.  As a general rule of thumb, I have found that even with a very efficient ascent, you need at least twice as much mass of lf/ox mix for rapier rocket mode as you need pure liquid fuel for jet mode, but probably at least 3x as much so we have margin for maneuvering is space.

Now it's time to test it.  Take it out for a spin and see how it performs.  Did it do amazing first try and reach orbit? Great, you can either take it as is and start using it, or if you are like me, see what tweaks you can make to make it even more efficient.  Did it not do so great, and fail to reach orbit?  It's time to debug.  Probably if it can't it's an issue with high drag, you can see how much drag each part is producing individually in their part windows by toggling on the "Show aero debug data in part action windows" debug option in the cheat menu, Alt-F12 => Physics => Aero.  There is also an option to bring up an Aero data GUI that will show you overall aero stats about your craft.

 

And if you really want to go down the rabbit hole and start your journey to being an SSTO wizard, I recommend watching this video (it's really long but also really worth it): 

 

And if you want to take your wizardry up a whole other level, also check out my playlist "Kerbal University".  Be warned, it's really dense so only jump in if you really want to go into the nitty gritty:

 

Edited June 17, 2024 by Lt_Duckweed

[Cloakedwand72]

On 6/14/2024 at 1:22 AM, Tecorian said:

Hmmm... do you mean these tanks, which we common know from the space Shuttle?

I think, these are indended to get rid of them after launch.

If you mean, building a STTO with mostly @stock-parts, have a look on my "standard-ssto"

I simply attached two big tanks on each side of the wings and use only a rocket motor for propulsion.

Not like the common sstos with partly airbreathing engines, you have to gain very quickly height above sea level.

I use a LFO engine from a mod, somekind realistic for KSP 1 (not for the real world) with a thrust of 1.500 and an isp of 315

dockingport is in the nose of my shuttle

Initially, i have LFO for about 5.000 m/s onboard, in a low orbit of about 80.000 m will have  still have about 450-475 m/s in reserve, enough for all manouvers in orbit around Kerbin

And yes, its possible to paint these tanks also in orange

 

 

Gonna try that design later! How does she fly? By orange tank carrier rocket I’m meaning skylon ssto that can carry the 36 tone fuel tank with spare to dock to station and deorbit.