How does pitch stability work?

In order to fly, an aircraft not only has to generate lift, it has to also be stable. What does this mean and does it happen? Hang gliders are flying wings so are unusual aircraft, in this video we look at how pitch stability is achieved for both conventional aircraft and unconventional aircraft such as canards and tandem wings.
I'm working on building a next generation hang glider design, as well as producing a technical series of videos to describe how hang glider (and more general aircraft) design works. Please support his work through my Patreon page, here: / hgdev

[@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.

[@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.