Bug: MK2 parts lift and backward drag is inversed

[JeQ]

I allways wondered why mk2 parts seems not work.
I did some research with aerodynamics on:
Other lifting surfaces gives more lift than backward drag when slightly angled to prograde.
MK2 parts gives more bacward drag than lift, approx same ratio than wings but opposite.

[miklkit]

Yes. There are mods for that. Personally this means to get to altitude as fast as possible to reduce drag, and it means the MK2 slow down faster when landing.

[gamename]

Good to know.

Was trying to do an 'early tech' space plane, saw the in-game text about mk2 lifting body, and figured I could try to get higher speed with a long mk2 body and minimal wings. I guess this explains why that seemed to make things worse. As I recall (I did a lot of disorganized trials), even a similar craft just with more wing did better than a 'mk2 missile'.

Would be nice to have a list of these counter-intuitive (counter-labeled :/) bugs.
Thanks for mentioning 'Aero on' .. hadn't known about that, will have to look

[ee]

higher cross section. it holds more fuel per unit length. So you'd expect some more drag at least.

[JeQ]

Originally posted by ee:

higher cross section. it holds more fuel per unit length. So you'd expect some more drag at least.

Not more back drag than lift tho (which makes it look those parts have them reversed). even basic 2.5m and 1.25m fuel tanks have more lift than backward drag, why would more wing shape part have worse lift/drag ratio? either basic parts are too good or mk2 parts are too bad.

[miklkit]

Not so. MK1 and MK2 parts hold the same amount of fuel. This is why it is best to use MK1 fuel tanks when possible on MK2s.

[ee]

Originally posted by JeQ:

Originally posted by ee:

higher cross section. it holds more fuel per unit length. So you'd expect some more drag at least.

Not more back drag than lift tho (which makes it look those parts have them reversed). even basic 2.5m and 1.25m fuel tanks have more lift than backward drag, why would more wing shape part have worse lift/drag ratio? either basic parts are too good or mk2 parts are too bad.

True. If so it seems like a bug. I wouldn't expect a lifting body to have anywhere near the efficient ratio of lift:drag as for a wing, but it should definitely NOT be as low as the inverse of it, and it should be higher than for a cylindrical fuselage.

If you peruse the list of examples of lift-drag ratios on the current wiki, the lowest you find is a house sparrow with a ratio of 4:1 . I'd expect a lifting body to be under this ratio, but optimistically above 2:1 assuming a modest and reasonable angle of attack. for ref, the wiki page: https://en.wikipedia.org/wiki/Lift-to-drag_ratio

If bug is verified, this deserves a prompt fix.

[desrtfox071]

Originally posted by ee:

Originally posted by JeQ:

Not more back drag than lift tho (which makes it look those parts have them reversed). even basic 2.5m and 1.25m fuel tanks have more lift than backward drag, why would more wing shape part have worse lift/drag ratio? either basic parts are too good or mk2 parts are too bad.

True. If so it seems like a bug. I wouldn't expect a lifting body to have anywhere near the efficient ratio of lift:drag as for a wing, but it should definitely NOT be as low as the inverse of it, and it should be higher than for a cylindrical fuselage.

If you peruse the list of examples of lift-drag ratios on the current wiki, the lowest you find is a house sparrow with a ratio of 4:1 . I'd expect a lifting body to be under this ratio, but optimistically above 2:1 assuming a modest and reasonable angle of attack. for ref, the wiki page: https://en.wikipedia.org/wiki/Lift-to-drag_ratio

If bug is verified, this deserves a prompt fix.

Game ceased development ages ago.

[JeQ]

i am wondering if this can be fixed just editing .cfg files of those parts somehow.

[miklkit]

There is a mod specifically for the MK2 that addresses this. It is "MK2 rebalance" and it is on CKAN. It works a lot like FAR but only for the MK2. I tried it and did not like it as it reduces drag by too much to suit me.

[ee]

Originally posted by miklkit:

Not so. MK1 and MK2 parts hold the same amount of fuel. This is why it is best to use MK1 fuel tanks when possible on MK2s.

I was surprised by the above. At least it is true for the liquid fuel only tanks on the full length segment of the lifting body fuselage. Perhaps on the lfuel+oxidizer does Mk2 hold more than Mk1? Visually it quite a bit larger.

So if Mk2 has no volume advantage, and not lift/drag advantage, then it is only good for looks and also it seems it acts structurally much less floppy and elastic versus Mk1 fuselage.

[miklkit]

Yes. The MK2 parts do add lift and drag and weight, but they also add bigger cockpits, crew compartments, and storage bays. This makes them more useful than the MK1 parts. And some people like their looks.

[gamename]

They do look cool. Seems like a kerbal could fit inside a service bay, maybe clinging to a ladder - although I think that would be 'outside', so no saving or warping. (Anyone else try to 'rescue' a stranded Kerbal by making him cling to a ladder on an unmanned probe?)

I guess the mk2 bicoupler could be useful to stick 2 engines on an otherwise mk1 vessel, but given this l/d stuff, ehhh