US Hawks Hang Gliding Association

I'm opening this topic to discuss issues related to the weight (actual body weight) of hang gliding pilots.

In the "Hello US Hawks" topic, Robert had asked:

Robert Hutchinson wrote:What's the cheapest, safest, best, etc. way for me to get safely airborne in Wisconsin?

Rick had replied:

Rick Masters wrote:A crane.

But maybe the desire to fly would give you the incentive to lose 100 pounds.
I've seen it happen.
It's worth it.
Don't even think about it at 300.

There were a few other postings (please see the original topic), and then Robert replied:

Robert Hutchinson wrote:Well, that sounds a little discouraging, since I haven't weighed 200 lbs since I was maybe 14? MCRD was able to get me down to 215, but I kept passing out; later, during my days as a professional Karateka (with only about 1% body fat) I was most productive at 225!

Maybe that crane is an option...or a tandem rated kite!

That being said, just how physically demanding is the sport? While I might still be able to pass the PFT (especially once my age of 52 years were factored in), I would certainly 'pay the price' for my efforts!

Just how demanding is it? I think the answer depends on the type of flying you're doing. As Rick mentioned, coastal dunes are relatively easy. On the other hand, there are sites where the turbulence is so great that no amount of physical effort can overcome it (at least in the short term). Some air can even turn jet airliners upside down. I haven't flown the sites that Rick has flown, and I haven't had the experiences that Rick has had. But even in my own (fairly conservative) flying I've been in situations where all of my effort was unable to keep the glider on course for a few seconds of strong turbulence. My instructor, Joe Greblo, has emphasized that a pilot should always be prepared for air turbulence that could induce a 180 degree change in heading ... at least for a short period. Flying in air like that can wear you out very quickly even if you're in good shape.

So with those thoughts in mind, I think there are really 2 issues regarding weight. The first has to do with whether you can find a glider to carry your weight, and the second has to do with whether you could control such a glider under the conditions you might expect to fly in.

As discussed in the other topic, tandem gliders can carry 400 (or more) pounds. So I think that resolves the first issue.

It's also assumed that a qualified tandem pilot (who's only about half of the total payload) can control the glider with his (or her) strength. But tandem pilots are expected to be in good shape, and they generally fly in relatively "nice" air. So the second question remains unresolved. Rick was right to bring up the issue, but I think the answer depends on the individual's own conditioning.

By the way, this topic is a good place to mention a phenomenon that results from living in a 3 dimensional world.

The weight of a 3 dimensional object goes up as the CUBE of its dimension. So if you took a 6 foot person weighing 200 pounds and turned them into a 12 foot person (with the same proportions) they'd weigh 200 x CUBE(2). Since 2 cubed is 8, that means they'd weigh 8 times 200 pounds - 1600 pounds!!

But of course, since they're bigger, they'd be stronger too. But how much stronger? It turns out that your strength is proportional to the number of muscle fibers in your muscles. But that number is proportional to the CROSS-SECTIONAL AREA of the muscle ... and not its total volume. So the number of muscle fibers goes up as the SQUARE of the proportion change. So by doubling the size of our original person, the cross sectional area has gone up by the square of that increase. Since 2 squared is 4, that means they'd be 4 times stronger.

So ... if you double the proportions of a person (or animal or building) you will increase its mass by a factor of 8, but you will only increase the strength of its muscles and bones by a factor of 4. So as animals get bigger, it's harder and harder for them to have the muscle and bone structure to support their weight (at least on land).

This explains why an elephant needs such massive legs to get around while a little bug can climb a vertical wall with spindly threads of legs. It also explains why gymnasts are almost always tiny. Any activity that requires total strength with very little weight penalty (like Sumo wrestling) favors a larger size. But any activity that favors strength-to-weight will favor a smaller size.

Robert, I'm looking at this from the perspective that there are good ideas, wishful thinking and bad ideas.
Games that take you over ten feet off the ground come with serious, potentially life changing (or life-ending) consequences.
If you are a big-boned guy and not a blob of fat on a medium frame, you might have a chance.
It's a matter of wing loading.
It all comes down to numbers and available equipment.
You could train on a school's 330 Condor and buy a used 60-pound Falcon 2 225 for real flying.
You can find the big Falcons fairly cheap on the used market.
Here's the specs.
http://willswing.com/wp-content/uploads/manuals/Falcon_2_10th_August_2005.pdf
There are other, probably better choices, but this is fine to look at wing loading.
One of my favorite gliders was a double-surface Moyes Meteor 190.
That sucker was double-sleeved all over the place because it had been used with a trike.
It weighed 90 pounds but that didn't matter because hang gliders don't weigh anything when you get them flying above your shoulders at takeoff. They all support their own weight.
I weighed about 180. My parachute, helmet, instruments, radio, water, heavy clothing, boots, camera food and medical kit brought my hook-in weight to 205.
The whole deal weighed 295 pounds. It handled like a dream. The wing loading was perfect for cross country and a stand-up landing out at high density altitude in light wind was possible.
295 lbs / 190 sq ft = 1.55 lb/sq ft
Your hook-in weight with ankle-support boots, helmet, parachute and harness would be 15 or 20 pounds over the rating of a ten-year-old Falcon 2 225. You would have to lose that weight first.
That should be easy. Probably will happen carrying that Condor around, anyway.
(A word of warning: don't settle for smaller gliders! Keep looking for the right one.)
Your wing loading would be excellent and the single surface Falcon will be easier to land. The weight of the whole deal would be 360 pounds.
360 lbs / 225 = 1.60 lb / sq ft
After you become proficient with the Falcon, you can transition to a large double surface ship.

Great posts by both you guys; Thanks Rick and Bob.

Bob, by your statement, it seems that there could actually be an upper limit to the weight of a pilot based on the eventuality of necessary muscle-mass to control a given wing area required to carry it! I'm now wondering what that theoretical limit might be...and how would one calculate it?

Rick, thanks for that follow-up; I also had seen the Condor 225 and wondered of its potential suitability. Also, after glancing at the spec sheets, I can see a fraction of what I don't know...WOW!

Now, you calculated a wing loading of 1.6#/sq.ft. and said that it would be excellent...from my previous reading on the subject, it seems that greater wing loading provides for greater maneuverability, while lesser wing loading makes for a gentler flight. Do I understand correctly? Is 1.6 the ideal for a beginner? Also...air density...Wisconsin is a significantly cooler climate than CA, this should provide for greater wing loading...right?

This is kind of getting interesting...

Hey Robert,
There is a boat towing operation (meaning boat towing hang gliders.) down at Lake Pepin on the Mississippi River.
When I get older into my 80's and can't carry a glider or just myself up a hill I could still Platform Launch (PL) from on a boat
equipped with a payout winch/reel. I and the glider would be equipped with flotation. I could land by skiing in on the surface of the lake on the pontoons hooked to the hang glider. Since a hang gliding boat towing operation doesn't require walking on the water or even running for that matter. There is no need to get into running shape for a landing.
The link will take you to a boat towing operation on Lake Pepin.
I've done many boat tow flights with my own boat rig and soared the 375' - 400' cliffs on the Wisconsin and the Minnesota side of the Mississippi River for an hour at a time. First I would fly then my boat driver would switch tasks with me and he would fly.
https://www.youtube.com/watch?v=AdtUfUJPwa8

First, thanks to Rick for your thoughts. (Robert, Rick is one of the "walk on water" people in the sport of hang gliding).

Second, I think Bill's ideas for water towing are also excellent. (Robert, Bill's experience with towing/landing on water is legendary).

Robert Hutchinson wrote:Bob, by your statement, it seems that there could actually be an upper limit to the weight of a pilot based on the eventuality of necessary muscle-mass to control a given wing area required to carry it! I'm now wondering what that theoretical limit might be...and how would one calculate it?

My comments about size (it does matter) relate to everything that you do that scales with your weight. That includes hiking up hills, climbing a tree, doing chin-ups, doing push-ups, and controlling a hang glider with the strength in your arms. In all of those activities, the forces required scale up with your weight (which grows as the cube of your size), but your strength scales up with the cross-sectional area of your muscles (which only grows as the square of your size). So the bigger you are, the harder it is to do the same things that seem easy for smaller people (like the spider walking up the side of a wall on spindly little legs). And that assumes that your proportions are the same (just scaled up and down). If the proportions are different (a hefty build versus a thin build) then things get worse.

As for a theoretical limit, that really depends on what you need to do. If you're in very smooth air, steering a hang glider is like driving a car. But as the air gets more turbulent, the forces you'll need to apply get greater and greater. At some point, even if you can move your weight as far as possible (constrained by the control bar and your hang strap) and as fast as possible, you still cannot apply enough weight shift to overcome the forces on the glider by the moving air. Those are conditions we all hope to never find. But if there's anyone on this forum who's experienced that kind of air ... my money would be on Rick Masters.

Robert Hutchinson wrote:This is kind of getting interesting...

There's a lot more to the sport of hang gliding than most people realize. We've been working on a free training manual for the US Hawks, but we've been stalled for a number of reasons. So until we actually finish it (and even after we do), there's a book by Peter Cheney called "Hang Gliding for Beginner Pilots" that I recommend. It has been the official training manual of USHGA, but I don't know if they still use it or not. If you can get a copy it might be helpful to you. Here's what it looks like:



You can also keep asking good questions and embarrass us into completing our own training manual.

Thanks guys, that boat-towing thing looks kind of fun! So, without being towed, what kind of running speeds are we talking about?

Robert Hutchinson wrote:Thanks guys, that boat-towing thing looks kind of fun! So, without being towed, what kind of running speeds are we talking about?

It's past you bed time Robert!
As experience is gained you can select what speed to run at to take flight.
At the smooth hill at Point of the Mountain Utah I have just leaned forward on the edge of the hill and lifted off into an 18 mph wind. When the wind died a little maybe one or two steps were needed. With no wind coming into the hill one could take a sled ride down to the bottom but at my age 68 I would pull a hamstring running fast enough to lift off.
Let's say a pilot takes off a hill with a ten mile and hour wind coming up the hill. He may have to run eight miles per hour.
But if a second pilot also hooks in the two would not have to run to achieve a 36 mph airspeed it would require much less even though two pilots were hanging from the same glider. The reason for this is the lifting force of the wind increases in a logarithmic progression not arithmetically.
A wind speed of 2 mph going to 4 mph the lifting force isn't just doubled the force jumps to 16.
I may have picked the wrong words there but I think you catch my drift??

I'm headed for bed it's 00:13 hours here.

you calculated a wing loading of 1.6#/sq.ft. and said that it would be excellent...from my previous reading on the subject, it seems that greater wing loading provides for greater maneuverability, while lesser wing loading makes for a gentler flight. Do I understand correctly?

No. Each hang glider is designed to carry a pilot within a certain weight range. Light pilots with light wing loading have to pull themselves further to the side in roll and farther forward or back in pitch than heavier pilots. The ship flies faster with heavier wing loading but the glide is the same. This is why racing or cross country pilots flying double-surface gliders will carry ballast, sometimes taking their wing loading over 2.0 lb/sq ft, so they can cover more ground at higher speed. But they always dump the ballast before landing. You want to land with light wing loading.

It's best to learn on a forgiving single surface glider. They are the slowest and most maneuverable of hang gliders. At it's upper range, the Falcon 2 225 is designed for a 300 lb hook in weight that translates to 1.6 lb/sq ft. As I just mentioned, if you overload the wing with a higher hook-in weight, it will fly faster and land faster. However, on a single surface ship, you will not have the same glide because you have a huge span of crossbar tubing perpendicular to the flow of the wind that degrades your glide ratio the faster you fly. The higher the wingloading rises above the design spec, the less will be your pleasure and safety and room for error.

air density...Wisconsin is a significantly cooler climate than CA, this should provide for greater wing loading...right?

No. Wing loading is a constant and is not a function of temperature. Performance parameters such as sink rate are temperature and air density related. I may have confused you with the term "high density altitude." Thus refers to air at 7000 feet, for example, being warmed by the sun in the afternoon until it has the unhappier characteristics of air at 9000 feet. Cross country pilots run into this all the time when they run out of lift a hundred miles from launch, flare at landing and fly into the ground. You're not going to run into this problem for a long time, if at all.

Also, any of Dennis Pagen's early hang gliding books from the late 1970s are treasures.