Huge dv for spaceplanes?

[Scottiths]

So I have finally been able to design, build, and fly space planes that SSTO successfully. However I have noticed something on MechJeb 2.0 stats. The mechjeb stats tab says I took 7000 delta-v to get to orbit. I only had 1200 delta-v in the rocket stage though. Is this normal? Or do I need to seriously rethink how I design space planes? Basically what happened is I burned a lot of regular fuel and kicked in the rockets for only the last 1200 or so. So maybe the jeb readout is high because it assumed I used oxidizer with that fuel? I don't know.

Here is the plane in question. It has the Kerbal Crew tank designed by someone (I forget at the moment) that seats 6 kerbals. Other than that and mechjeb 2it is entirely stock.

Here is a picture of it (and a link in case the picture dosent load because I am inept at it)

img https://www.dropbox.com/s/4dt4vvlj2jz5h7a/screenshot49.png img

[UmbralRaptor]

Airbreathing designs really do use a ton of ÃŽâ€V to get to orbit. It just doesn't matter because the Isp of KSP jet engines is >20,000 s most of the time.

[Scottiths]

So I am not doing something wrong then? Because I read somewhere on these forums that the advantage of space planes is that they use relatively less fuel and are entirely reusable. I get the reusable part but as far as I can tell they consume TONS of delta v. (how did you make the real delta? What is the alt code )

Or maybe I am confusing dv with fuel consumption... Because it only consumed something like 200 L of fuel (but the readout said 7000 dv).

[RoboRay]

You are confusing delta-v with fuel consumption. Yes, you required a lot of delta-v, but the engines delivering that delta-v were extremely fuel-efficient jet engines. So, your actual fuel quantity consumed was considerably lower than if you have simply delivered 4.5km/sec with rockets.

[Scottiths]

Ok, it all makes sense now. Thanks for the clarification. I should have noticed this myself really, the whole plane only carries something like 500L of fuel jet fuel

While I am here though, are there any tips for re-entry to get back to KSC for a landing? I have tried several times now, and I can land just fine but I can't do it on the runway (which would be cool)

I come really close though... One time I actually ended up landing next to the runway because I couldn't tell I wasn't lined up right.

[RoboRay]

Are you gliding after reentry, or do you still have fuel remaining to operate the jet engines? If you've got fuel, reentry anywhere near KSC should allow you to fly to the runway.

If the issue is getting properly lined up with the runway, remember that it runs due east/west. So, if you're aimed right at it and your heading is 090 or 270, you're in position and on-heading. To help you get lined up, make some little rovers with unmanned pods and park them just off each end of the runway, and drive another one or two a few km west of the runway, staying in line with it. Their location markers on the screen gives you a great visual reference for getting lined up even before you can see the pavement.

[Scottiths]

I like the rover Idea... I might set up a huge line of them leading to the runway