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Wing Loading


Phr00t
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Hey all,

I fly a Dudek NemoMoto Large (27 m^2). I'm 140lbs (body) + 5.5kg (wing) + 56lbs motor + 6lbs gas + 7lbs equipment, which puts me around 100kg all-up weight. If I my weight divided by the projected area of my wing, I get a hair above 4 kg/m^2 loading. However, I know it is common knowledge that for PPG flying, you want to be on the high-end of your weight range on your wing. The Dudek Nemo Large is weighted for 80kg-115kg, so I fall at just about the center of the weight range.

I worry because my last few flights have been rather bumpy -- I think it might just be from some wind shear in the area, but other pilots do not complain as much as I about bumps, and they fly much faster in the air than I do (they fly Muse wings, which are also DHV-1). I know they are on the higher end of their weight ranges.

However, looking at other paraglider wings, their weight ranges are much lower for comparable sizes. For instance, the APCO Karma SMALL is only around 0.4 m^2 smaller, but the weight range is 60kg-90kg... so flying "heavy" on that weight scale would equate to being at about the same wing loading as I am on my Dudek Nemo.

Am I correct to be making such comparisons? Do you suspect I'd notice a reduction in bumps in the same air, if I was more heavily loaded on my wing? Any other suggestions?

Thank you!

- Jeremy

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Hi Jeremy.

How do you know other pilots, who are faster or more heavily loaded, are being "bumped" less?

Reason I ask is that other wings always look quite stable from a few hundred feet away even though they are experiencing exactly the same "bunps". Also one pilot's "bump" is another pilot's slight ripple, its all very subjective.

As far as your detailed question, no, I dont think being more heavily loaded will reduce the bumps. You will fly a bit faster so maybe be out of the bump sooner but the major downside of being more heavily loaded is that any collapses or other events will be more dynamic (meaning much faster and with much more energy) Most wings get their certification from what happens when the wing is tested at the top weight and max speed.

My advice is enjoy the bumps and learn to fly with them rather than against them. Imaging a canoist in white water...rolling and pitching with the waves, using body weight and controlling paddle to weave amongst the bumpy water, .....air is a fluid and just the same......technique and understanding make flying bumpy air enjoyable, not equipment changes.

You are actually at teh ideal (design) weight for your wing, it doesnt fly any better than that.

Paraglider pilots learn this stuff on an SIV course, learning how to recover a collapsed wing and how to fly the bumps. The confidence this gives is remarkable and I wonder why paramnotorists dont take advantage of an SIV.

Lastly your size and weight range comparisons are not really comparing like for like. The Apco may well be pulled into a tighter arc, so even though only slightly smaller the lifting area is considerably less. And the spect ratio may be different too.

The design load per square meter is the figure to compare for wings of a similar aspect ratio, otherwise the comparison is not helpful.

Francis

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Thank you for your helpful reply.

I don't know how "bumpy" these other guys are in the air.. they might be just as bumpy as I, but they are not thinking about "wing loading", so they don't complain/worry like I did. I was hoping I didn't have to go for an equipment change, so it is nice to hear you think increasing my loading wouldn't help.

My instructor suggested letting out my trimmers into the wind to improve penetration (which I guess would somehow reduce bumps?).. but I hear this also reduces stability.. so I haven't been to quick to try it.

Generally, I just keep a constant brake pressure in bumps, and let up on the brakes if I feel the wing go back any. However, what I really want to do in bumps is gain altitude to get out of the wind shear and find smoother air -- should I keep brake pressure while giving full power to climb out of the bumps, or would this risk too high of an angle of attack? I've heard the phrase "hands-up" to go up :-)

- Jeremy

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Very diffficult to give detailed instruction over the forum...but....

I dont know what you mean by "wind shear". I understand this to be the plane between to air masses moving in different directions or at different speeds or both. So climb above it or fly below it. This would not give rise to bumps but rather one big bump as you fly through.

You might be referring to the feeling that your wing wants to turn one way then another the face the wind This is likely to be near the ground, either lee rotor from obstructions (many hundreds of feet downwind) or thermal tendrils coallescing (bubbles swirling up from the gorund to merge together at one or two hundred feet into a thermal (lava lamp style;=)

Or you might mean actual thermals, as you enter your wing surges forward than rocks back, you swing underneath and drop, feels like a bump allright!

Or you might be flying in disturbed air after a windy day just got flyable (take offable). Often the air on such a day is in a pretty bad mood and taking off into it results in a punch up.

If it is thermals (most likely) they are your friend. "turn in lift" is the mantra. It is not optional, TURN IN LIFT. you feel the wing surge forward and you check it or you will swing underneath it. Instead lean to the lifting side and turn into it, as you swing through turn the other way and circle. You will climb without power.

Or you can just fly straight through and call it a bump.

either way the wing may collapse but a Nemo will pop straight back out, probably before you even notice. Just look where you want to fly and lean towards the flying half of the wing. A Nemo will fly straight on with half the wing down and re-inflate spontaneously,

Enjoy.

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i think this is very interestin i too have been thrown up and down and i would be interesting doing one of the courses which teach you to handle the air in a good way were would i get a course like this as it can only be beneficial?

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If you can get hold of a copy of Sky Wings there are plenty of SIV courses being advertised in the mag. One that l reccommend is by a pilot called Jocky Sanderson. He holds courses in Turkey and France. The one in Turkey, the take off is from a mountain 2000' and once airborne you can see the Blue lagoon and every landing is on a soft sandy beach.

Mike

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I generally only fly about an hour before sunset (and some past sunset with my strobe) -- so I can't imagine it being thermals.

I say wind shear, because at the ground -- the wind is just about dead. However, once I get a few hundred feet in the air, my wing starts to sway and bump in the increasing winds aloft. I checked my GPS unit, and it said I was going 13MPH, so there was a ~11MPH wind difference between the ground and a few hundred feet. It is at this few hundred feet I start to not climb as much, because I worry about being under full power with the bumps. This causes me to stay in the "sheary" area... I should keep climbing and get out, I assume.

There ARE 900ft/270m mountains 2mi/3.2km south of where I was flying from, and the ~11MPH headwind was from the south. This might be the cause of some of the bumps, but I was under the idea that they were far enough away for the winds to settle before hitting our launch site.. *shrug*

Thanks again for the pointers!

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multiply the height of the obstruction by 700 and that is how far away the disturbed airflow will affect. 900 ft is a big hill! over 200 km away is out of range of that baby! yes that is wind sheer and the transition to smooth air above may be quite "interesting". Check the wind to the south of the mountain before flying. If it is strong you will get that sheer. What is the location?

If you are confident the wind above is not too strong try climbing out in a circle. This will keep your wing presurised and you will "slice" through the bumps. (not too tight, less than 45 degrees bank), use enough power to keep the turn and climb constant, All control inputs smooth and progressive.

:P

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you feel the wing surge forward and you check it or you will swing underneath it.

a 'little' picky I know, but just keeping it clear in the interest of.......well, clarity :D.... The above comment is not true of a reflex wing, you dont 'check it' (brake a little to stop the wing flying over your head) in fact quite the opposite (leave it alone to let it do its thing)

info taken from.... from http://www.flyparamania.com

Our Reflex technology and paramotoring

The biggest evolution in our sport, aside from improved engines and better understanding of Paramotor frame geometry, is the introduction of our reflex profiles, into wings developed specifically for powered flight. It is now generally recognized that it has helped turn our sport into a practical and relatively safe, fun form of flying.

:: What is Reflex Technology :: Video Demonstration :: Reflex Certification ::

Some History

History has a habit of repeating itself. In the early eighties, similar developments took place as pioneers of ultra light aircraft bolted engines onto their existing hangliders. Whilst these early ultralights flew ok, they were not ideal.

A wing designed for power had a completely different set of requirements. A new breed of wing with stronger construction, different handling and more stability, was born

I was privileged to have been part of these early pioneering days. My name is Mike Campbell-Jones and for some inexplicable reason I was imprinted with a passion for light weight flying machines. My experience spans through hangliding, ultra-lights, general aviation, gliding, ballooning and paragliding to present day paramotoring.

It proved particularly valuable when developing the original Reflex paramotor wing in 1994.

Understanding Reflex technology

Reflex profiles are not new; they were first used extensively as far back as the 1930’s in tailless aircraft, such as the Horten brothers flying wings or the Fauvel tail-less glider, It provided these wings with aerodynamic pitch stability, where there was none.

Hangliders also adopted reflex in profiles to give gliders a positive trim. It improved safety, as it helped prevent tumbling. The effect was simple enough, more reflex more pitch stability, though less speed and performance as the angle of attack was increased.

But used in a paraglider Reflex profiles have a different effect. Because unlike the hangliders or flying wings the angle of attack is maintained through the lines connected to the pendulum weight of the pilot suspended below, in the same way as a wing with a fuselage and a tail-plane, acts as a lever, controlling the wing.

Reflex profile enhances this pitch stability, by adding an effective elevator into the wing, whilst keeping the centre of lift/pressure close to the leading edge. The wing loading is higher, as less of the wings area is used for lift. So stability and speed are increased without the need to change the wings angle of attack.

There are many other factors but the end result is there is also more efficiency at speed and a greater speed range (a flatter polar curve). So a bigger distance between the stall and cruising speeds and generally less likelihood of being robbed of that precious air speed in turbulence.

For paramotoring, this is an exciting development. ....................

More informarmation on Reflex stuff and the rest of the explination

SW :D

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you feel the wing surge forward and you check it or you will swing underneath it.

a 'little' picky I know, but just keeping it clear in the interest of.......well, clarity :D.... The above comment is not true of a reflex wing, you dont 'check it' (brake a little to stop the wing flying over your head) in fact quite the opposite (leave it alone to let it do its thing)

Quite right, Simon. Jeremy is flying a Nemo so my comment is with that in mind.

But I flew a Paramania Revolution in quite interesting conditions recently, over several flights and found that it does just exactly as you describe. It is, in fact, quite astonishing !!!!!! When a paraglider "goes light" on one side you have to respond or take a collapse but the Revo goes light and just hangs there in the sky until it takes up the load again.

Astonishing :lol::lol::lol::lol::lol::lol::lol::lol::lol::lol::lol::lol::lol::lol::lol::lol::!: It made me giggle to fly it.

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My next wing might be a reflex one.. they always sound so interesting :-)

This is the field I take off from:

(url doesn't work)

Moody Bridge Road, Hadley, MA, USA :wink:

There are some mountains to my south.. however, not a bad place to fly (if it wasn't for the bumpy air)

Here is a video of me flying in the area (except for the first faceplant :wink:) -- no bumps during the video though.. I must have been above the bumpy air and never really "hung" out in it to really notice it before:

Do a Google Video search for "phr00t's hijinks"

Thanks!

- Jeremy

PS. I tried to put the URLs here, but I get some log_spam() missing function error :shock:

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I think you may have to make a few posts before you can post links??

To stop spammers.

Welcome by the way, would have said hi sooner but have been busy flying and teaching my arse off in the lush sun we have been having.

SW :D

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