It's my blog, so I'm going to indulge myself. Thank you, and you're welcome...whichever.
I saw this little 4-minute vid pop up this morning and having watched hang gliders do aerobatics on video and in person for at least 15 years or more, I just can't get enough of the righteous purity of this one.
...Let me set it up for you. First of all, note that the launch is near sundown. Why? You want very smooth air, no thermal activity, as thermals—especially in places like Utah in summer—can wreak havoc on a plan like this. If you hit a 2,000 ft per minute up blast whilst in the dives he's doing, it could take you to over 10 G. The glider will be A-OK, but he's not wearing a fighter jock pressure suit.
Next, pay attention to how the energy accumulated from the first dive is miserly guarded throughout (what I love the most). There was the first big dive and throughout the rest of the routine he just goes back to the till for some change here and there. Meaning: he never loses all his built up energy, but goes back in to keep it near the initial level. This is very important for aerobatics under glide, no power. He's exchanging attitude.
Next, he uses that stored energy at the end of a loop, and not go into another loop (as so very many do), but to do a roll. Realize: the straps he's hanging from are not rigid. Therefore, he must maintain positive G of 1+ throughout; otherwise he would immediately fall into the glider and that is hit & miss. These gliders are structurally designed to take negative G, but only for their own weight and structure—not a 170 lb guy falling into the sail at a point. Falling into the sail almost always results in a cute deployment (and a broken $6,000 glider).
OK, watch the video and then one more thing about it. ...About 4 minutes.
Willard with Smokes from Ryan Voight on Vimeo.
Perhaps my favorite thing beyond the R.A "Bob" Hoover-esq thing of keeping 1+ G in a roll, so as to not spill any liquids in the cockpit, was his spin at around the 2-minute mark of the video.
Hang gliders won't spin on their own. You have to put them in one and hold it (notice how he is fully pushed out). I've done these, but not while family is watching because it looks like a spiral dive. As soon as you relax, the glider recovers on its own. Do check that out, about 2m into the video.
As a final note, powered aircraft are fun and I did all my training in a tail dragger, a Citabria. I loved that, because even totally stock, they are moderately aerobatic and so from lesson 1 and way before my solo flights, I was doing spins. Here's what it looks like.
That's 28 spins and I've done 8 or 10 max (It's an altitude thing). But the thing is, once you reduce power to idle, bring up the nose to a stall and at the point of stall, kick the rudder right or left depending on which way you want to go, the aircraft just loves the spin and will stay in it so long as you hold the stick back full. Relax that full back stick, kick in a bit of opposite rudder, and recovery is a cinch. Then add power. Fly home.
Alright, so there's my built up flying indulgence...logged.