Icarus: My first attempt at an SSTO (stock). (I think it can get into orbit)

[Finwolf]

Spinning isn't caused by the engines. Your lift is in front of the CoM. Check that in the SPH. Use tweakables to check dry mass and wet mass CoM in relation to the lift. It should always be just behind the CoM.

[I_Killed_Jeb]

You really don't need 2 turbojets for your mk.III design...

[Armchair Rocket Scientist]

Made some more changes, added two more fuel tanks, and had to move the clamp-o-tron further up. I think I could have made it to refuel but I guess the tanks changed where it takes fuel from, jets were full, and I lost all fuel for the engine at the amount in the second picture.

http://i42.tinypic.com/14aet50.jpg

http://i39.tinypic.com/2ql63q9.jpg

Unless they're hidden inside the RCS tanks, that design doesn't have any fuel lines. Adding a pair from the outboard tanks to the center tanks should fix that. For good measure, you can add a pair going from the central tanks back out to the jet engines. That should solve your fuel flow problems.

I also notice you have 193 units of excess liquid fuel. This is WAY more than you need for cross-range capability. Swap the two jet fuel tanks for either a single jet fuel tank or a FL-T400 with all the oxidizer removed (FL-T400 has more fuel for a smaller dry mass, but has a slightly lower impact tolerance) and save over a ton. With less mass to lift into orbit, you can remove some of the LFO tanks as well.

For flying a single kerbal into orbit and back, a plane with a liftoff mass of 10 tons should be more than sufficient. I've done it with 6, and that's with only 2 intakes. Others have made working craft even lighter.

[XOIIO]

I put them underneath the wings posting that. I think once I know how to actually get these things into orbit the most efficient way, then I won't need as much, maybe I'm just really sucking at piloting them, I probably am. I saw scott Manley's video of one where he had enough to get into LKO, launch a probe, return and fly back without refueling. He was using a mod pack though so maybe he had some higher fuel capacity parts. Can't recall the exact video.

[XOIIO]

Unrelated to this, but I decided I want to make a small VTOL vehicle, I came up with the Jetstream VTOL car, this is a sneak peek, it will have a thread all of it's own tomorrow, or sooner depending how long I can stay awake, but it's pretty awesome

[Giggleplex777]

You don't need that big of a plane for it to be a SSTO. My latest one weighs 5.5 tons!

The R.A.P.I.E.R. makes SSTOs sooooo easy.

[Spartwo]

Agreed even though they aren't better than composite engines.

[kizentheslayer]

lol looks a lot like my first ssto i eventually except i had a t15 on the back instead of the airospike. I would rub out of fuel on me just short of a full orbit. I think i ended up sticking the second stage up of my duna rocket on it and called it a shuttle

[Jouni]

Spinning isn't caused by the engines. Your lift is in front of the CoM. Check that in the SPH. Use tweakables to check dry mass and wet mass CoM in relation to the lift. It should always be just behind the CoM.

Often it's just easier to remove excess wings, until there is barely enough lift to take off before the end of the runway. The more lift the spaceplane has, the more careful you have to be with balancing it to ensure safe re-entry and landing.

Take this monster as an example:

With 37.2 tonnes of mass and four R.A.P.I.E.R. engines, the plane accelerates to around 105 m/s at the end of the runway, which is enough to raise the nose but not enough to take off. To get the thing off the runway, you have to raise the nose and use thrust to compensate for the lack of lift. Later, during jet-powered ascent and acceleration, you need to maintain a 27-degree pitch just for level flight, and a bit more to keep climbing steadily.

On the way down, with a dry mass of 18.2 tonnes, things look completely different. There is now enough lift for easy flying, and the control surfaces are more than adequate to compensate for the lack of balance. The plane remains fully controllable all the way down, and it's the easiest plane of its size to land I've ever built.

[Finwolf]

My point was to make the desing so you don't have to compensate. It's pretty fast and easy to check CoM relation to CoL. I usually use lots of wings and I don't have a problem with spinning.

[Jouni]

My point was to make the desing so you don't have to compensate. It's pretty fast and easy to check CoM relation to CoL. I usually use lots of wings and I don't have a problem with spinning.

Spaceplane design has many trade-offs. If you concentrate on balance, you have less control over the appearance of the plane and the order of the components, and adding and removing parts becomes harder.

I did a little experiment with the spaceplane in my example. I increased the dry mass by 3.4 tonnes by adding a large RCS fuel tank behind the main hull of the plane. This changed the balance so that CoL was in the front of CoM during takeoff, but it was nothing the plane could not handle. Getting to orbit took a bit more fuel than usual, but the plane could still have reached my refueling base at 120 km.

After the deorbiting burn, I tried to make a gliding landing to KSC runway. Unfortunately CoL was still in the front of CoM, so the plane was a bit unstable with large angles of attack. Because of that, I had to restart the engines to reach the runway. The landing went fine, except that the poorly attached RCS tank fell off at touchdown. Still, it was a pretty nice example of the flexibility of the flies-like-a-brick approach to spaceplane design.

[Bean]

Now that I am a bit better at flying them I got similar results, although I had a bit less liquid fuel and half as much oxidizer. I am going to swap out the engine nacelles, I hardly see them used.

What ascent profiles do you guys use? I pretty much get to a 50 degree angle as fast as I can upon liftoff, wait to 20km, nose down, and try to keep level and get as much speed as I can, then nose up 90 degrees and rocket until my AP is good. (mix of a couple tips ive seen and trial and error.)

I go straight up at 70 degrees until around 16km, then level off and build speed while gradually climbing, with this SSTO it was around 2000m/s at 30km before I switched to rockets, then I just did a little pulse to keep the apo at 80 when it dropped to 70 (due to drag) and once out of the amto, circularize at apo