Tips for my SSTO?

[Cranium]

I currently have a very nice in atmosphere plane, but I am trying to push it into LKO. Unfortunately, the engines keep flaming out around 25Km, resulting in a flatspin that I have to recover from.

What can I do to improve this design?

I know that at some point, I have to add some tanks with oxidizer, so that I can use some radially mounted engines for finally reaching orbit.

[PolecatEZ]

Dude, you're doing it wrong. All those intakes are useless at high altitudes. You need the blue glowy ones, those work up high. The big scoops, turbines, and nacelles currently serve no useful purpose other than aesthetics. With a 3:1 or 4:1 Intake:Engine ratio and carefully reducing your throttle, you should be able to keep the engines active well into the 30-32km range. Also, you seem a bit over-engined - make the last engine a single rear engine in the center, this should also protect you from flameouts.

[Cranium]

Oh, okay. I was not aware that different intakes have different altitude efficiency ratings. So I could just swap out my front intakes for the 'blue glowy ones', and I can swap out the nacelles for fuel. I currently like my twin engine design in the center, though.

I can cut the drag then, by reducing the amount of intakes I have as well. I think if I get rid of the radial intakes surrounding the body, but leave the wing engine intakes, I should be fine, right?

[Daid]

You do not have any rockets on it? I don't think you can make it to orbit without any rocket engines on there.

[Cranium]

Yeah, no rockets yet, I was pushing it to the absolute limits of in atmosphere maneuvering before I add rockets.

[Hooligan Labs]

"Intake spam" is very common for doing high altitude jets: http://forum.kerbalspaceprogram.com/showthread.php/27682-Highest-jet-only-periapsis

Many fantastic SSTO designs are available here: http://forum.kerbalspaceprogram.com/showthread.php/11214-The-K-Prize-100-reusable-spaceplane-to-orbit-and-back?highlight=k-prize

One of them got the community spotlight for going all the way to Duna and back, carrying an orange tank!

I did a video on my SSTO for the Grasshopper challenge, but it used rockets instead. I lack the patience and/or skill to do it with jets.

[Cranium]

Alright, so any tips for improving the CoL and CoM? Currently, they are matched *almost* completely near where the intakes on the body are attached. It makes it fairly balanced for takeoff, and just makes it slightly rear heavy when in upper atmosphere, due to weight changes. It doesn't cause too much trouble, and the AvPa does manage to control it fairly well, with minimal correction from me.

[Naelo]

Alright, so any tips for improving the CoL and CoM? Currently, they are matched *almost* completely near where the intakes on the body are attached. It makes it fairly balanced for takeoff, and just makes it slightly rear heavy when in upper atmosphere, due to weight changes. It doesn't cause too much trouble, and the AvPa does manage to control it fairly well, with minimal correction from me.

It is a general design rule for SSTOs to have the center of lift just behind the center of mass to account for that.

This doesn't really negatively affect the handling at takeoff.

EDIT: If it ai'nt broken, don't fix it. Just remember that rocket fuel tanks have a lot more weight and more potentioal to shift your CoM.

[Syhrus]

I just finished a video about the basics, but it seems you've got those downpacked. At 25,000 you should be pushing the limits of your jet engines to get as much horizontal speed as possible. Once you're maxing that out to drag, you should have a pair of rockets to get you through the final levels of the atmosphere. From there, just fly like a normal rocket.

[Jokurr]

My SSTO only goes up to about 24-25 km before the rocket kicks in, or at a horizontal speed of about 1200 m/s. As far as the type of intake goes, the blue ones may or may not be better, I don’t know. But you don’t HAVE to use them exclusively, my SSTO only has 2 of them and 12 scoops for a total of 14 intakes, I can achieve orbit no problem. I wouldn’t worry about pushing your jet engines any further than what you’ve got, time to add a rocket to give you that final push.

[Cranium]

I think what I might do, is swap out the circular intakes for the high altitude ones, remove the intakes from the main body and top/bottom of the wing engine tanks, and swap out the central engines for aerospikes. I think I'm also going to swap out the body fuel tanks and engine nacelles for rocket fuel tanks of the same size, leaving the wing engine tanks as pure rocket fuel.

[Cranium]

-random refresh double post-

[Motokid600]

Have you considered the B9 pack? Some REALLY good stuff in their.

[Cranium]

I'd prefer not to use mods at the moment, because it's my first few weeks with the game. After I get some accomplisments under my belt, I might add some mods.

[baracksimposter]

having 2 aerospikes seems like a little too much thrust, try the LVT-909 or whatever it is called, if that dosent work use the small gimballing rockets and aerospikes don't have gimbal so you would have to use RCS because at that altitude your control surfaces wont work that well anymore.

Edited June 7, 2013 by baracksimposter

[Syhrus]

I actually find that aerospikes add too much weight to your craft. My designs use a pair of LV-T30's for the final stage into space, and then a smaller LV-909 for orbital controls once I'm clear of the atmosphere.

[Cranium]

Alright, so I took into consideration what you guys said. Unfortunately, I am still having issues. I ended up completely redesigning the plane. Can you tell me why it won't get above 27Km?

It currently runs out of oxygen at 27Km, but fuel is alright. I would like to see what you guys say, since I am still learning the Kerbal Physix.

[Galacticruler]

more intakes

thats the key.

[foamyesque]

If you can get to 27KM just turn your danged rocket engines on

[Cranium]

Intakes were the key! I just added some more, and I was finally able to get into orbit!

Melgas looks REALLY happy that he doesn't have to die on this mission!

My first EVA that did not end in complete disaster!

[CalculusWarrior]

Congratulations! SSTO planes are really hard, and you've accomplished it in your first few weeks with the game!