Getting an SSTO space-plane into orbit?

[Dinjoralo]

So, I've managed to make a plane that can get off the landing strip without veering into the hangar. So, how can I fly it into a stable orbit? The two main things I'm thinking will be issues are the jets not working at 18,000 meters, and the possibility of running out of fuel.

Here's a picture of the Spess Plenn. Marvel at how it can actually fly.

[Johnno]

All SSTOs have additional rocket engine(s) to boost them into orbit. Jets are fuel efficient but as you know can't function without air, so they're used to climb high and pick up initial speed.

[zxczxczbfg]

There are a couple of mods that add tanks filled with nothing but the IntakeAir resource, and lots of it, allowing you to operate outside the atmosphere. Other mods add airbreathing jet engines that can run off Oxidizer as well, for when the IntakeAir runs out. Some craft with particularly powerful jet engines can just fly really fast to pick up speed, then "slingshot" themselves into orbit unpowered, using only its high inertia and low drag to get itself onto a suborbital path. Allows for airbreather-only engines, but can make orbital maneuvering difficult without some kind of non-airbreathing thrust system.

Edited August 16, 2013 by zxczxczbfg

[Dinjoralo]

All SSTOs have additional rocket engine(s) to boost them into orbit. Jets are fuel efficient but as you know can't function without air, so they're used to climb high and pick up initial speed.

Oh, do they? Thanks for telling me, I'll rework my design a bit to add normal rocket engines.

[Bekiekutmoar]

I finally managed to get a small space-plane into orbit several days ago. A minimum of 2 air intakes for each air-breathing engine is required, 3 or 4 (or more ... !) is recommended. My ascending angle in the first 10 km is mostly between 15 en 30 degrees, after that 5 or even a little bit less. In the upper atmosphere the jet-engines will flame out inevitably but throttling back can kick 'em into action again. With my design I can increase speed to over 1700 m/s with jet-engines only, then the two LV-909's can finish the job and bring the craft into stable orbit. But this depends on your design ofcourse.

You better clear the dense atmosphere (below 30 km) before activating the rocket engine(s) to reduce atmospheric drag.

[lammatt]

try to load the stock aeris4A and mimick its build when you try to build a plane.

it's pretty good and basic and sounding indeed (tho many people argue the otherwise)

- minimal redundant weight on wings (lift just barely larger than the weight at takeoff)

- very agile (or some may say instable)

- a lot of spare fuel available upon reaching orbit (if you can achieve >1.4km/s speed before switching to rocket)

-----------------

anyways...

if you want to get a plane into orbit... you have to

- have enough lift

- have enough thrust

- get into reasonably high speed before the jets die ( a 80 x 80 km orbit takes ~2250m/s; and you probably want to get to >1.4km/s before you switch to rocket; depending on how much rocket fuel you have)

- have your center of lift trailing the center of mass for stablity (the more behind=> the more stable but less steer-able... you want to find a spot at with the plane is stable but steer-able)

Edited August 16, 2013 by lammatt

[glacierre]

@Dinjoralo

I am reasonably confident that a plane like you show in the first post will never get to orbit. The total thrust must be aligned with the center of mass, and by the looks of it, you have placed a couple of engines well over it.

This is not a problem at low height, where you have plenty of authority because of dense air (or maybe not, since you neither have canards...), but when you go higher (+20 km or so) you will not be able to compensate the torque any more and (in this case) nose will go down no matter what you do.

IMHO, for a craft that size, 2-3 jets should be enough. The... 5? 7? you have are way, way too much. More jets -> more fuel -> more weight -> more problems. If you are new to space-planes start small.

[Dinjoralo]

Yeah, there are six jets on there. I'll remove two of them, and make another two rocket engines for when I get to 180,000 meters. Thanks for the help, everyone!

Also, yay for being able to have an avatar!

Edited August 16, 2013 by Dinjoralo

[Camelotking524]

One big thing to remember is to cut back on your throttle after reaching thinner atmosphere. Like around 10km, start cutting back on the throttle with small increments to match the your lowering air intake. When you can no longer cut back on the throttle without slowing down, light the rocket engine and shut down the air breathers before the flame out.

[Dinjoralo]

One big thing to remember is to cut back on your throttle after reaching thinner atmosphere. Like around 10km, start cutting back on the throttle with small increments to match the your lowering air intake. When you can no longer cut back on the throttle without slowing down, light the rocket engine and shut down the air breathers before the flame out.

Oh, that's probably why my plane goes absolutely mental at around 10,000 meters. And I finally figured out how to set Action Groups, so I can turn off all the jets at the same time.

On an unrelated note, I'm starting to get annoyed with Jeb always being the pilot whenever I go to the hangar and back.

[Dinjoralo]

So, I've managed to completely ground the plane in only a few minutes, and after a good couple hours, it's back to a state where it can go up. And that's as far as I'm getting today, because I'm starting to get tired of this.

[unwisemonk]

You'll need some turbojet engines, and 2-3 intakes for each one. You will need much more oxidizer than liquid fuel.

[Zaeo]

you now know why we don't use space planes today, despite their capabilities.

[Spyritdragon]

The stock Aeris 4A has only 1 RAM intake and 1 radial intake per engine, and the radial intakes quickly lose their use, yet i can still get it to orbit with a reasonable success rate...

[lammatt]

WRONG

flip the plane top side down

you can see there's another pair of ram intake

there's a total of 3 intakes per engine

The stock Aeris 4A has only 1 RAM intake and 1 radial intake per engine, and the radial intakes quickly lose their use, yet i can still get it to orbit with a reasonable success rate...

[Dinjoralo]

Oh man, I got my plane into orbit! Thanks for your help guys, I learned a lot both making and flying this. Now I need to figure out how to set this thread as "answered".

Edited August 17, 2013 by Dinjoralo

[RC1062]

Any advice on how to fly the <insert suitable adjective> things? I've finally given up my professional pride and am asking for help. Yup, I've never got a SSTO up to orbit since space planes were added...

Here's what I got. I figure it should do the trick.

[Johnno]

Any advice on how to fly the <insert suitable adjective> things? I've finally given up my professional pride and am asking for help. Yup, I've never got a SSTO up to orbit since space planes were added...

Here's what I got. I figure it should do the trick.

Like mentioned before, have a look at the Aeris 4A.

As for your particular plane, I'd try changing several things;

- Swap circular intakes for RAM intakes.

- Remove 2-3 of the RCS tanks.

- Remove one cockpit.

- Add a bit more rocket fuel.

Depending on how well it's balanced, I'd recommend a reaction wheel as well. You could also check out this thread, regarding troubleshooting.

[Captain Sierra]

Any advice on how to fly the <insert suitable adjective> things? I've finally given up my professional pride and am asking for help. Yup, I've never got a SSTO up to orbit since space planes were added...

Here's what I got. I figure it should do the trick.

Not enough intakes or rocket fuel. Use Ram intakes if you can.

Do you have KSPX? If so, replace some of that monopopellant with the cylindrified fuel tanks by KSPX. If not, lose at least 2 of them. For a plane that light, you should be able to dock in under 100 units of monoprop and you have 600 there.

More intakes, more rocket fuel (perhaps less jet fuel) less monoprop.

You could probably shorten the wing some too and still be fine. SSTO planes are inherently fast so smaller delta wings provide enough lift and less drag.