How to fly Spaceplane in the most effective way?

[korda]

After a really high number of tries (often ending up in crashes at runaway) I finally managed to get my first Spaceplane to orbit, but I'm not fully satisfied...

It's more complicated than example planes I've seen here on forums (shown as simple examples of Spaceplanes that can reach orbit), because either I didn't make good enough design (I didn't try to make hard copy of what I've seen on screenshots) or I wasn't able to utilize it right; I don't know which one is the case here. My small planes were on good track to achieve Kerbin orbit, but I was ending up lacking fuel, even when I didn't left wasted fuel for jet engines.

I was trying to fly it this way:

- at beginning of flight I was going with almost 45 deg. up, gaining altitude as fast as I could

- when I saw Intake Air starting getting low (something about 10000 m.) I was changing angle a bit, going more horizontally and slowing down lose of Intake Air

- around 20000-22000 Intake Air was getting really low so I was being forced to enable rocket engine

Did I do it right?

[ThePsuedoMonkey]

How fast did you get it before firing the rocket?

[Shrike42]

In order to maximize your speed off of the turbojets, you need to cruise between 20,000 and 30,000 and keep your engines running as long as possible without stalling out. If you employ the turbojet intake stacking trick, you can keep your engines running for much longer, and keep pushing. It's possible to get to 2000 m/s velocity on turbojets alone, and wind up on suborbital 'hops'. Hitting the rocket engine once you're on a 60,000 m + 'hop' should let you get into orbit a bit more efficiently.

But you've got the right approach. If your plane can climb at 45 deg off the runway, do that and then start to level off around 18,000. Try to aim for the horizon and maximize intake air, building up speed and slowly going higher. Throttle down as your intake air starts to approach .08 per turbojet, and then throttle down further and further. Then kick on the Rocket engine and go for it.

[bsalis]

First up, if you have not done so already, i would put the outer two jets and the inner two jets on separate Action group keys. You will want to shut down the outer two first, and let all intakes feed the inner two before shutting them down.

Next up, do one or more test flights. Open up the Resources Tab. Then fly up to high altitudes, and purposefully cause an engine flameout while watching the IntakeAir on the Resources Tab. that will tell you the threshold that you need to be mindful of. Repeat this running on the inner jets only.

So armed with those numbers you should be able to do a better ascent. I would say run all 4 jets as high and fast as you can until you are not gaining much speed. Then engage the rocket and shut the outer engines down. Climb, then shut down the inner two jets when they are near flameout. Also close off all the air intakes to reduce drag.