For a 9-11 style burning building what is the smallest wing surface area required for a hang glider (or similar device) to be able for it get a 200 lb man safely to the ground at non-lethal speeds.
I dunno - do you consider broken limbs acceptable or are you hoping for injury-free landing?
Given the tight clearances around skyscrapers in downtowns such as NYC and Chicago, and the inevitable wild air currents you get from those much less what is kicked up by a fiercely burning building… I just don’t see this as a controllable descent. Particularly with someone with no flight training/experience whatsoever, but even with those skills I’m not convinced this is doable.
However… I’m sure someone more knowledgable about hang gliding will be along shortly.
Have you perhaps considered parachutes?
I read the OP and envisioned thousands of people smashing out their office windows and jumping out with their hang gliders…only to soar right into nearby buildings and then falling, and of course a few of them smacking right back into their own builiding, and very few, if any actually landing.
I’ve seen a number of experienced hang gliders eat dirt even when landing in open fields… in a crowded downtown? Nope.
Steerable parachutes seem like a better idea (more compact, easier to set up/control), but I think the OP wants lots of ‘escapees’, and parachutes are quite tall and wide compared to hang gliders.
You’re probably looking for something in the neighborhood of 3-4 lbs/sqft. Assuming the hang glider would weigh at least 40 pounds, that’s a minimum of 60 sqft.
But it’s almost certainly true that such a device would require some pilot skill.
Likewise for a modern sport parachute I seem to recall (back in my daring days) that some people were loading high-performance 0-P canopies up to around 2 lbs/sq ft. Bigger than a hang-glider but they weigh far less.
As Xema notes, this is not a device you’d give to a beginner.
There are very safe ram-air parachutes built for pilots and whatnot that were designed to bring an unconscious person down safely, no operator control. I saw some photos of them (big slow 7-cell, I think) in action, they were up around 270-300 square feet.
A regular round canopy might actually be a bit safer in this case - they pretty much go straight down. You’d need a big one to keep landing forces low when you consider panicky untrained folks landing on cement. Perhaps you could have a built-in ground proximity sensor that inflates an airbag under the person’s butt a few feet before landing?
Parachutes and gliders are totally unworkable. Much better would be some sort of friction chute that can be unraveled and you can simply hop inside and slide down. I’ve seen those before - they’re designed so that they apply enough friction to you that your ‘terminal velocity’ is very slow. You just jump in and slide straight down.
I believe there was some difficult problem with them that wasn’t overcome. It either cost too much, or they were too dangerous, or something.
It’s probably getting the guy that jumped in front of you out of the way before you pile onto his shoulders!
The challenge with any friction based device is that 100% of the potential energy of yor starting height is converted to heat that is then applied to your clothes & body. Some of the heat energy goes into heating the chute, but the rest (ballpark 50%) goes into heating you.
And for any meaningful height and quick transit through the system, that’s simply more heat flux than you can take without significant burns.
As well, all the heat you leave in the chute is there for the next person to experience. If a whole bunch of people are queued up to slide, the later folks are going to get cooked. Yes, the chute is continuously radiating heat into the environment, but at what rate? Not enough.
A big problem is that any high rise has so darn many people in it. One or two might be able to get away by parachute or glider… but there’s just not enough room between buildings to accomodate a couple hundred people - much less a couple thousand or even a few tens of thousands such as might get with a WTC type skyscraper.
There is already an Evacuchute on the market.
There is a commercial that has been running lately, (I don’t remember the product being advertised.) where a sign worker falls backward off the sign and just before he hits the ground, airbags inflate, ala the Mars landing technique. That is the rescue product I would like to have.