Plane With Jet Engines & Rocket Fuel

[chatyakksp]

Noob question.... I understand that rockets use fuel and oxidizer and that the fuel containers for them already have the right balance by default.

I'm doing a mission for atmosphere scanning above 19Km and know that jet engines only work so far and then I need rockets to help with the height.

I keep the rocket engine off until I need it however by that time, some fuel has gone down in the rocket fuel portion just from flying - and the oxidizer runs out really quick relative to the fuel.

https://steamuserimages-a.akamaihd.net/ugc/839209486473125943/9B964AA8182EB283633197D31EECE96EF4EAD851/

Can anyone point me in the right direction on why oxidizer is going down so fast?

[bewing]

Fuel generally drains from all available tanks, equally. You have 6 tanks that hold liquid fuel, it looks like, but only two that hold oxidizer. So when the rocket is lit, the oxidizer is draining at the correct rate from both the tanks that hold it, and the liquid fuel is draining in a balanced way against all the tanks that contain LF. But you have a hell of a lot of LF on that plane, and a relatively small amount of oxidizer.

Edited July 9, 2017 by bewing

[qzgy]

1 hour ago, bewing said:

generally drains from all available tanks, equally

Exceptions being fuel lines and adjusting flow priority.

 

Rockets, which use oxidizer, are generally much more inefficient when compared to jet engines. Therefore, they consume more fuel quicker. Oxidizer being one part of this, it goes pretty quickly while on jets, you have very efficient source of thrust, but not as much versatility and thrust.'

I would say switch 2 of the outboard tanks to one that contains LF and Oxidizer. That should help fix the problem. Also - do you really need that many jets and solar panels? You do realize that jets (and maybe rockets, though I can't say for sure) produce EC, right?

Edited July 9, 2017 by qzgy

[Spricigo]

7 hours ago, qzgy said:

Also - do you really need that many jets and solar panels? 

No,  you don't need.  Actually all the drag and mass is seriously hindering that plane.