yuri_base

Jeff, are you saying that when flying in close proximity to someone above you you get more lift? Do they get more lift as well or get sucked down (even when not in your burble)? If you build a tight 20-way vertical stack, will it fly at 7:1 glide ratio? One thing is for sure: it'll look very much like Maxim's plane. Android+Wear/iOS/Windows apps: L/D Vario, Smart Altimeter, Rockdrop Pro, Wingsuit FAP iOS only: L/D Magic Windows only: WS Studio

Yo! There is a big confusion that gets repeated over and over again, and that is taking the concepts of powered flight and applying them to nonpowered gliding flight. The result is - wrong conclusions and delusions. First of all, the force diagram for powered and nonpowered flight is totally different. In powered flight, there are 4 forces: weight W, lift L, drag D, and thrust T. In level powered flight, these forces form a simple "+" shape: weight down, lift straight up, drag horizontal and pointing back, thrust horizontal and pointing forward. The sum of these 4 vectors is zero in sustained flight: W + L + D + T = 0 or simply L = W D = T If you know L/D for given trim, you can easily calculate thrust required for level flight: T = D = W/(L/D) Or vice-versa: if you know thrust during level flight, you know L/D: L/D = W/T In nonpowered flight, there are 3 forces: weight W, lift L, and drag D. In gliding nonpowered flight, these forces form a simple right triangle shape: weight down, lift pointing at an angle up and forward, drag pointing at an angle up and back. The sum of these 3 vectors is zero in sustained flight: W + L + D = 0 or by Pythagorean theorem W^2 = L^2 + D^2 since L and D vectors are perpendicular to each other and weight is triangle's hypotenuse. If you know L/D, you can easily calculate lift and drag: L = W*(L/D)/sqrt(1 + (L/D)^2) D = W/sqrt(1 + (L/D)^2) (these are simply that Pythagorean theorem rewritten in terms of L/D) Do the equations for powered and nonpowered flight look similar? Since you're sleeping, I'll answer for you: no. Totally different animals. Secondly, the design goals are vastly different. Airplanes need to take up a certain load, transport it from A to B as fast as possible with as little fuel as possible, and take off and land at slowest speed possible. Airplane can have cruise speed of 500kts and landing speed of 175kts. Now, we know that dynamic pressure is proportional to speed squared. So at 175kts the dynamic pressure is only 12% of that of at 500kts. How does it generate as much lift at only 12% of dynamic pressure as at 100%? To achieve this feat, big airplanes use several methods. First, the simplest one, is to increase angle of attack, which increases the coefficient of lift. But it may not be enough of a measure for such wide range, so it extends the flaps (increases surface area), increases the coefficient of lift by modifying the camber of the wing, and uses high-lift devices (various appendages that increase coefficient of lift), slats, and even lift from the fuselage. Everything is put in line to land that two hundred ton monster! From the formula for level flight T = D = W/(L/D) we see that the higher L/D, the less thrust is needed for cruise level flight. That's why in level cruise flight, the trim is streamlined as much as possible: flaps are flush with the wing, high-lift devices and other "stuff" are hidden as much as possible, the fuselage is horizontal (in-line with the airflow for minimum footprint). On landing, all those lift generating technologies are used to bring the big bird home safely. On take off and landing, they only care about generating as much lift as possible from limited airspeed, and for that they sacrifice L/D, the trust needed increases, but they simply crank up the engine to overcome the increased drag! Slow landing speed is achieved by increasing power to overcome the increased drag. Back to wingsuits. In high-performance suits, we look for only one number: L/D. There's only one person on Earth thinking about taking off in wingsuit and just a few thinking about landing one, but for the rest of us - straight L/D people, that is, not the extra gay flocking crowd - it's sustained flight at maximum possible L/D that's of interest. As you can see now - if you're not sleeping yet - none of the "technologies" used in airplanes to generate lift at the expense of increased drag - is useful for our purpose. High-lift devices - not useful. Poor L/D. Extending flaps - not useful. Poor L/D. Slats - not useful. Poor L/D. Any "cool developments" in powered aircraft should be taken through the prism of L/D: do they increase L/D or both L and D at the expense of lower L/D to achieve other goals? Using Concorde as an example when talking about wingsuits = nonsense. Let Concorde engineers have their problems and us - our problems. Using supersonic planes as an example when talking about wingsuits = nonsense. Supersonic - and powered at that! - aerodynamics is completely different from way-subsonic glide of wingsuits. Fuggedaboutid! Discussing wing profiles of various - subsonic or supersonic - powered aircraft as example for wingsuits = nonsense. Wing profiles for powered aircraft are chosen based on given design criteria - payload, speed, landing/takeoff characteristics. If they need to sacrifice L/D to meet these criteria - they will without blinking their eye. In trash can you go! Mentioning that powered aircraft use their fuselages to create more lift as an example for wingsuits = nonsense. Those supersonic jets strive for every inch of lifting surface to land on an air-carrier deck at ridiculously low speed compared to their supersonic cruise speed. Pure insanity! Etc. etc. etc. etc. Let's make 2008 special by thinking before we say something! Let's be a little bit smarter than in 2007. Remember, it's the Year of the Great Wingsuit Revolution, so don't relax! Yuri Android+Wear/iOS/Windows apps: L/D Vario, Smart Altimeter, Rockdrop Pro, Wingsuit FAP iOS only: L/D Magic Windows only: WS Studio

Do you have data for lift and drag as functions of angle of attack? And if yes, can you share it? Android+Wear/iOS/Windows apps: L/D Vario, Smart Altimeter, Rockdrop Pro, Wingsuit FAP iOS only: L/D Magic Windows only: WS Studio

That translates to 121mph horizontal airspeed. Taking into account that you're lightweight, can you really fly at 121mph AND have the best glide? You sure the wind was only 12kts? Who doesn't love the downwind ride in fast uppers! And the epic effort to stay upwind when you try to penetrate 100mph and fall straight down like a brick! Android+Wear/iOS/Windows apps: L/D Vario, Smart Altimeter, Rockdrop Pro, Wingsuit FAP iOS only: L/D Magic Windows only: WS Studio

I'm not making this up - I just calculated that the amount of energy generated by a terminal impact (120mph) of a 200lbs jumper is enough to lift a 6-pack of beer to 13,500ft. A ridiculous fact of elementary physics, but fact nevertheless. What a coincidence! P.S. Here's the calculation. The kinetic energy of a 200lbs (90.8kg) bogy moving at 120mph (53.6m/s) is KE = (1/2)MV^2 = 130600 Joules. A 6-pack of 12oz cans weighs about 5-6lbs (say, 2.5kg), to lift it to 13500ft (4120m) requires PE = mgh = 101000 Joules. By the way, that terminal impact energy is equivalent to 31 grams of TNT. Android+Wear/iOS/Windows apps: L/D Vario, Smart Altimeter, Rockdrop Pro, Wingsuit FAP iOS only: L/D Magic Windows only: WS Studio

There surely IS a magic formula, and it's very simple: Amount of weight you need to wear to increase your fallrate by dV is equal to your exit weight W times 2 times dV divided by your fallrate V without weights: dW = 2*W*dV/V This is a simple consequence of drag being proportional to the square of speed. I'll leave the derivation to interested readers. This formula is valid for small increments in speed - like a few mph. For large increments, simply square the ratio of the new and old speeds and that's your new total weight. Example: your exit weight is 150lbs and fallrate is 114mph. You want to match 120mph. You need to wear 2*150*6/110 = 16lbs weight. Using V = 120mph gives this table which should be good enough estimate in most cases: Fallrate increase in mph Weight (as % of your exit weight) 1 1.7 2 3.3 3 5.0 4 6.7 5 8.3 6 10.0 7 11.7 8 13.3 9 15.0 10 16.7 Next request for magic formula!

I think most of this almost 2x increase in lift and drag coefficients comes from increases AoA due to incorrect balance of armwing and legwing surfaces. While the 10% decrease in performance is due to different wing planform and smaller aspect ratio. Android+Wear/iOS/Windows apps: L/D Vario, Smart Altimeter, Rockdrop Pro, Wingsuit FAP iOS only: L/D Magic Windows only: WS Studio

That would be a meaningless comparison. We're discussing aerodynamics of wingsuits, not the progress that skydiving gear made in 50 years. It's either both you and Macareena in Razors with Trangos or both of you with chest mount reserves and huge rounds.

Based on the numbers James posted (Stealth: L/D = 2.2, Vx = 65mph, Vy = 30mph (as derived from Vx by L/D given) and Vampire: L/D = 2.4, Vx = 100mph, Vy = 42mph (again, derived from Vx by L/D given)), we can get some insight into aerodynamic properties of Stealth and Vampire. Simply plug these horizontal and vertical speeds into that spreadsheet with wingsuit equations and see what the adjusted lift and drag coefficients are. For Stealth, they are Kl = 17.9, Kd = 8.12. For Vampire, they are Kl = 7.86, Kd = 3.28. (all times 10^-5, and in English units) Adjusted coefficients Kl and Kd are proportional to nonadjusted (classic, dimensionless) coefficients Cl and Cd and inversely proportional to wingloading. What is the total surface area of Stealth compared to Vampire? Robi and James could answer this question precisely, but suppose for a second that Stealth has 30% larger surface area. So from the numbers above it follows that Stealth has the coefficient of lift Cl 1.75x higher than that of Vampire and coefficient of drag Cd 1.9x higher. Is it good or bad? What does it tell us? I think it tells us a lot. Since both lift and drag coefficients increased (almost doubled), while the lesser dampening effect of the body (due to larger area of the wings) should have decreased, that means two things. First, it's misbalanced and the AoA settles on a too high a value. 2.2 corresponds to 24 degree glide angle, while 2.4 corresponds to 23 degrees. Not much of a difference, but what about the difference in pitch angle? Vampire is a steep suit: the pitch angle for best glide is below the horizon, usually from my experiences and observations of others, about 10-15 degrees below the horizon. That gives us AoA of about 8-13 degrees and results in very fast - and efficient, too - flight. What is the pitch angle for Stealth for 2.2? I wouldn't be surprised if it's flat with horizon or even slightly head-high, due to its overpoweringly large arm wing. That's at least 24 degree AoA. Slower and less efficient. Actually, as indicated by the above coefficients, a LOT less efficient. But in terms of L/D, part of this inefficiency is hidden by lesser dampening effect of the body since body now is smaller fraction of the total surface area. Arms wings can be relaxed to get more steep pitch angle, but then it decreases efficiency by other mechanisms. Or you can bend in the waist more forward and again, efficiency is decreased because the wing is now distorted too much. See, a lot of food for thought and further development can be extracted from just a couple of ordinary-looking numbers. Yuri Android+Wear/iOS/Windows apps: L/D Vario, Smart Altimeter, Rockdrop Pro, Wingsuit FAP iOS only: L/D Magic Windows only: WS Studio

But if YOU recreate Maussenna's suit today and YOU learn it as much as you know Stealth, will YOU glide significantly worse in it than in Stealth? If not, why do you think so? If yes, what's the progress? What's your L/D in Stealth? What would be your L/D in the 50 year old suit? Android+Wear/iOS/Windows apps: L/D Vario, Smart Altimeter, Rockdrop Pro, Wingsuit FAP iOS only: L/D Magic Windows only: WS Studio

The whole flock going at 117mph and doing 3 minutes? This should be called extra straight as opposed to the other popular term these days.

6 miles in 165 seconds = 131mph average ground speed. Minus 14mph for the wind = 117mph horizontal airspeed. 11000ft in 165 seconds = 45mph average vertical speed. Average L/D = 117/45 = 2.6. Do you think 117mph sustained horizontal airspeed over almost 3 minutes is a reliable number? If you passed James in Stealth on your flight, you'll be moving at 52mph past him?

I wish I had a magic calculator with a big red button labeled "L/D" :) It's not possible to calculate L/D from only the numbers you gave because the effect of the wind on glide ratio depends on you horizontal speed. What was the duration of your flight? And how do you know that you actually had constant 12kts wind all the way down? Android+Wear/iOS/Windows apps: L/D Vario, Smart Altimeter, Rockdrop Pro, Wingsuit FAP iOS only: L/D Magic Windows only: WS Studio

So for Stealth for L/D=2.2 the sustained horizontal speed is 65mph and vertical 30mph? What are your sustained horizontal and veritcal speeds for Vampire's L/D=2.4? Android+Wear/iOS/Windows apps: L/D Vario, Smart Altimeter, Rockdrop Pro, Wingsuit FAP iOS only: L/D Magic Windows only: WS Studio

Justin, what glide ratio you're observing in SM1? Android+Wear/iOS/Windows apps: L/D Vario, Smart Altimeter, Rockdrop Pro, Wingsuit FAP iOS only: L/D Magic Windows only: WS Studio

James, what glide ratio you're observing in Stealth? And what is your glide ratio in Vampire? Android+Wear/iOS/Windows apps: L/D Vario, Smart Altimeter, Rockdrop Pro, Wingsuit FAP iOS only: L/D Magic Windows only: WS Studio

Here's a table illustrating the "significance". At L/D = 1.0 - typical glide ratio for lazy flocks - both lift and drag are 71% of the weight. So we can say that drag is as significant for flocking as lift. At L/D = 2.5, lift is 93% of weight and drag is 37%. For a high-end sailplane with L/D = 80, lift is 99.99% of weight and drag is only 1%, but we can't say that this tiny drag is insignificant, because they put a lot of research and $$ to get that 1%. L/D Lift/Weight Drag/Weight 0 0.00 1.00 0.5 0.45 0.89 1 0.71 0.71 1.5 0.83 0.55 2 0.89 0.45 2.5 0.93 0.37 3 0.95 0.32 3.5 0.962 0.275 4 0.970 0.243 4.5 0.976 0.217 5 0.981 0.196 6 0.986 0.164 7 0.990 0.141 8 0.992 0.124 9 0.994 0.110 10 0.995 0.100 12 0.99655 0.08305 14 0.99746 0.07125 16 0.99805 0.06238 18 0.99846 0.05547 20 0.99875 0.04994 25 0.99920 0.03997 30 0.99944 0.03331 35 0.99959 0.02856 40 0.99969 0.02499 45 0.99975 0.02222 50 0.99980 0.02000 60 0.99986 0.01666 70 0.99990 0.01428 80 0.99992 0.01250 90 0.99994 0.01111 100 0.99995 0.01000 Android+Wear/iOS/Windows apps: L/D Vario, Smart Altimeter, Rockdrop Pro, Wingsuit FAP iOS only: L/D Magic Windows only: WS Studio

I've never seen shark's skin. Is it like sand paper or more like gaffers tape? Android+Wear/iOS/Windows apps: L/D Vario, Smart Altimeter, Rockdrop Pro, Wingsuit FAP iOS only: L/D Magic Windows only: WS Studio

For air, hitting the vertical membranes of the [almost] closed cells head-on is about as bad as hitting the stagnant air in front of the open cells. I think that small inlets are to make the wing more rigid. High dynamic pressure created by high speed provides plenty supply of air, so inflation is not a problem. Imagine a thin inflatable mattress (like ThermaRest). When you inflate and seal it, it's quite rigid. If you make many big holes in it and maintain the same pressure dynamically by a pump, with air running out of the holes, the mattress won't be as rigid as before. More rigid wing means it can be flatter spanwise. The lift vectors from all areas of the canopy are now pointing more vertically, resulting in higher lift. Android+Wear/iOS/Windows apps: L/D Vario, Smart Altimeter, Rockdrop Pro, Wingsuit FAP iOS only: L/D Magic Windows only: WS Studio

Ok, ok, let's stay on topic, boys! The topic is not "Bigger is better!" or "Size does matter!" If it were, I'd have posted a picture of the biggest airplane or biggest nipple in the world (we all know who's the happy owner of it, his name has 5 letters: J, a, r, n, o). Maxim's airplane with 20 wings is an apotheosis of thoughtless "more is more" approach to development. "The Wright Brothers built a plane with 2 wings... well, I'll build a plane with 20 wings!!! Woooohoooo!!! I wins, u sucks!" The point is, we reached the end of the road. We maxed out the size of fabric, but we haven't applied any of the basic aerodynamics ideas to it. Wingsuiting made as much progress in the last 80 years as from Wright Brothers to Maxim. Rebellious minds of all countries, unite in the righteous struggle for the beautiful wingsuits of the future, against flying mattresses!!! If not YOU, who will make the future?! Android+Wear/iOS/Windows apps: L/D Vario, Smart Altimeter, Rockdrop Pro, Wingsuit FAP iOS only: L/D Magic Windows only: WS Studio

It's Fidel's contribution to wingsuit revolution. Android+Wear/iOS/Windows apps: L/D Vario, Smart Altimeter, Rockdrop Pro, Wingsuit FAP iOS only: L/D Magic Windows only: WS Studio

I could do a 3 minute flight if I jump from stratosphere. :) The armwing pressure is about that in Phantom, definitely lighter than in V-2. Solid inflation, semirigid inserts in the leading edge, Fidel Castro fiber inserts that help profile the wing and big hand grippers all help reduce the arm strain. Android+Wear/iOS/Windows apps: L/D Vario, Smart Altimeter, Rockdrop Pro, Wingsuit FAP iOS only: L/D Magic Windows only: WS Studio

Yo! We're in "more is more" phase of wingsuit "development" right now. Well, what do you think? Is more more? Is less less? Is more less? Is less more? Or we're in "get the talented aerospace engineer see our retarded stuff and laugh and show us the basics" baby period? Or should we just start from scratch, learn those basics and start designing amazing lean&mean flying machines of the future?! Yuri Android+Wear/iOS/Windows apps: L/D Vario, Smart Altimeter, Rockdrop Pro, Wingsuit FAP iOS only: L/D Magic Windows only: WS Studio

I flew Rigor Mortis a couple of times on New Years in Z-Hills and it does rock! Some of you probably heard the words I said after the first flight on it: "Fuck yeah, sound ideas DO WORK!" Glide ratio: after exit, I could immediately feel something different (while looking at clouds around and below me): I can go there... no, wait a second... I can go THERE, and THERE, and THERE, and THERE... and still return to DZ. The feeling of increased horizontal range I can cover and the need to adjust my flight pattern was striking. Inflation: arm wing is completely sealed by gay spandex sleeves, the inflation is superb. Any wingsuit that has wings and body sharing the same pressure now seems to be absurd. Why would you need to inflate the "fuselage"?! To get more drag? Leading edge: it's smooth and semirigid (RM has semirigid foam insert). When you fly the feeling is as if you have rigid wings. Arm pressure is quite light. I wish the leading edge was more profiled and "pointy". Balance: it's off. I couldn't put the pitch angle into more aggressive stance due to overpowering lift from the arm wing. "Spanish whore" analogy when referring to leg wing spread is not enough - he needs to make the leg wing 4-6 inches longer ala V-1 to compensate for armwing's superb inflation and lift. The speed was not sufficient, I could feel there's potential there. I had to bend in my waist too much to get more horizontal speed, but it decreased the glide. Turns: were surprisingly sharp. It's almost like you just think you want to make a turn and the suit already does it. Deployment: felt a bit twitchy due to high pressure in the wings. It's just a matter of getting used to. Thumb cutaway cable: great idea! Less time is needed to look at your arms than look down left and right. Usability: The suit was quite tight on me, so it sucked: sitting in a tightly packed plane with 10 horny men about to commit sodomy in the air aka "flocking", in those tight lycra arm sleeves, with armwing inserts spreading the wings out, felt like an end of my virginity... this suit totally sucks! Although hooking it to the rig was supereasy. Zippers as armwing attachments? Not for BASE, thank you. Overall: great suit. It's good to see sound ideas and bright thinking at work. Disclaimer: what do I know, I only made 2 jumps on RM and flew as well in it as after 100 jumps on V-2. BUT: everything, including RM, pales in comparison with what will see in our fucking amazing revolutionary 2008. Fasten your seatbelts, monkeys!!!

Gay holding hands pajama parties??????? *gasp* How can I sign for one??? (As a photo reporter, of course.) Tell me all about it. Android+Wear/iOS/Windows apps: L/D Vario, Smart Altimeter, Rockdrop Pro, Wingsuit FAP iOS only: L/D Magic Windows only: WS Studio