Advanced plane aerodynamics - FAR

[Torham234]

Hello everyone. I have a question for anyone experienced in the FAR mod. Recently I was designing a "flying wing" type aircraft. I am using the FAR and the procedural wings mod. I have made two very similar designs, witch for some reason have very different flight behaviour. My question is just what is the cause of this.

The first aircraft is the B13 stratospheric stealth jet. It is extremely fast and can easily achieve Mach speeds shortly after take off. At the cruising altitude it can fly Mach 5 without much difficulty.

Codename: B13

Weight: 5.19 ton

Fuel: 150

Cruise height : 27 km

Cruise speed: ~ 1600 m/s ( Mach 5)

The second is the B15 stratospheric long range stealth plane. B15 is only a fraction heavier, but for some reason it is much slower at all altitudes. It still handles more or less the same as the B13.

Codename: B15

Weight: 5.51 ton

Fuel: 320

Cruise height : 25 km

Cruise speed: ~ 1300 m/s ( Mach 4.2)

My question is, just why is B15 so much slower compared to B13? I have tried different air intakes on both planes, that does not seem to be the case. The B15 is just as slow with 2 ram intakes instead of the 4 radials. Its not just the cruise ceiling, the B13 is much, much faster straight after take off and after that at all altitudes. Yet the weight difference is only 0.32 tons at take off...

[Wjolcz]

different fuel tanks in the middle. the bigger ones have higher drag.

[Torham234]

Thanks for the info.

Its a little odd that it would make such a difference, but after some tests I have to confirm that the flatter fuel tanks have indeed much more drag over the simple tube. Shame really, because I like the B15 design much more...

[Read have Read]

Well I for one think the B13 looks cooler.

[s20dan]

I have found those radial intakes to be such a drag... *hears pin drop*

Replace them somehow with an inline intake and I think the performance between the two craft would be more similar... Or just remove your inline intakes on the B13 and replace them with the 4 radial intakes to see if that does indeed cause a lot of extra drag.

Edit:

The B15 is just as slow with 2 ram intakes instead of the 4 radials.

Oops, I should make a point to read every part of a post

Edited June 26, 2013 by s20dan