How does pitch stability work?

[@ecclesheat]

Awesome video Tim really well explained.

[@MooSurfer]

Excellent video Tim, really well explained so even I can almost understand it. Ready to start designing the Darren Beown Extreme Aircraft now!

[@mikedekock4437]

Great video. looking forward to the next one!

[@lizhikai5587]

Nice video about pitch stability. However, researches have shown that the vertical position of CoG also influences pitch stability. This may leads to critical behaviours such as auto-diving. I'm researching on this but have got little detailed knowledge. Have you investigated about this and would you like to discuss it? Thanks.

[@avianhanggliders1985]

Yes, this is called pendulum stability. The next video will go into pitch stability as it applies to hang gliders and I'll include that.

[@lizhikai5587]

@@avianhanggliders1985 Magnifique! I can share thesises that I've found about the theme.

[@nickcaci7238]

Seems to me we don’t give much thought on the outer tip flow control ( the last 3 to 4 feet of the span ) by utilizing narrow 1/8 inch gap flow slits from the 1/4 cord redialing aft to nearly to the trailing reinforced edge. ( This would be more practical on a single surface glider). At lower airspeeds high angle of attack, the slits will allow some higher pressure flow from below to transition up to the upper low pressure near the wing tip vortex rotation only instead of one large vortex we could have multiple smaller vortex’s reducing induced drag and lower stall speed. If only some ambitious HG designer could take an old bagged out Falcon onto a test vehicle rigged up with flow tuffs, leading edge smoke and cameras. We have already experimented with leading edge vortex generators which manly deal with boundary layer control at higher speeds in hang gliders and some trikes. I like to think we can somehow simulate what large soaring hawks do with there multiple wingtip feathers accomplishing multiple small vortex virus one large one.

[@ecclesheat]

How effective do you think the Combat tail would be at stopping a tumble?

[@avianhanggliders1985]

I'll be covering tumbles in the next video. Adding more area behind the centre of gravity (the further away the better) will certainly resist tumbling, so in that sense then yes, adding a horizontal stabiliser will act to resist it. Angling that tail down relative to the wing (longitudinal dihedral) also adds pitch stability too. The Combat also has a pretty wide nose angle though, also the planform of the wing (straight tapering) means you don't get the area further back from the wing tips, so that would count against it. So comparing a Combat with tail to other toplesses without tail, it's hard to say which is more tumble resistant. They all pass the same pitch tests, so do all have similar characteristics in terms of pitch stability. Pitch stability and tumble resistance aren't exactly the same thing though (although they are correlated), I'll need another half hour video to go into all this fully though.

[@ecclesheat]

@@avianhanggliders1985 looking forward to it. Love this stuff.