How do paper airplanes fly physics


Heavy better thick paper Light better thin paper Time aloft for a paper airplane can be optimized by either throwing a paper airplane with a short wing span real high, and having it glide downward fairly quickly what I door making a fragile long wing span plane click launching it gently from as high as you can reach, or something in between. The primary tradeoff is wingspan - short wings can withstand a fast throw, but don't glide so well.

Long wings glide great, but can't be thrown hard. A basketball player with a vertical reach to 10 feet could seriously challenge my record. I think better flight times, and for me more fun is had, with the smaller swifter planes. To achieve this I launch the plane as fast as possible, straight up. As it ascends the force of gravity and the force of drag slow it down until it stops. From there the plane's natural stability ensures it begins slow gliding flight.

A simplified explanation goes like this: InKen Blackburn set a world record for a paper plane flight that lasted I have tried using highly cambered airfoils optimized for slow gliding, but they tend to degrade the ascent. I believe a nearly flat, uncambered airfoil does this.

For maximum height and for a good transition to gliding flight, the throw must be within 10 degrees of vertical. Also for maximum height, the throw must be as fast as possible. I used some of the principles of biomechanics science of the mechanics of the body together with baseball throwing techniques and shot put throwing techniques to develop the throw I use. I would like to thank my high school coach Mike Lauten for enrolling me in his biomechanics class. I estimate the plane leaves my hand at 60 miles per hour. This is based on two independent methods.

First, I have had my baseball pitches clocked with a speed gun at about 65 miles per hour, and I think my paper airplane throws are about the same speed. The second method was mathematical. Knowing the plane reaches a height of from 50 to 60 feet, and the drag coefficient of the plane, I determined the launch energy required kinetic. During the ascent the plane's angle of attack is near zero, resulting in near zero lift and allowing the plane to go virtually straight up.

This is crucial for two reasons.

  • There are many reference to low speed flight which are applicable to paper airplanes.
  • So as far as reducing drag goes, the thinner the better.
  • This is what happened to the modified plane—it experienced a greater amount of drag, which pushed it back more than the original plane.

In slow flight the plane is adjusted to produce a lift coefficient of about 0. If the plane were rigid, it would trim to the same lift coefficient at all speeds, with a sharp pull up into a loop at speeds higher than 10 mph. At the speed I launch it, it should enter into a 40 g loop, but it doesn't.

How do paper airplanes fly physics

The second reason zero lift is important is because of drag. If the plane stayed at its 0. The plane does not go to exactly zero lift, and spirals a bit during the ascent to maintain a near vertical trajectory. Sometimes I have to add some rudder deflection to aid the spiraling to improve the ascent. I have also experimented with introducing intentional asymmetries into the plane to aid spiraling.

So why and how does the plane go to near zero lift? I'm not really certain, but I think I have the answer. As I said, it would trim to a 0. I suspect the reflexed section the up elevator to pushes the rear portion of the wing down, producing a more curved airfoil which wants to pitch the nose down and trim at a lower lift coefficient. Also the weight of the fuselage at the middle of the plane results in a large root bending moment as the plane pulls g's, so that the wings flex upward added dihedral which effectively lowers the angle of attack and lift coefficient the plane ascends at, with the wings returning to their original dihedral as the plane slows.

I need to take some high speed video to analyze what happens during the launch. The airfoil of the plane also affects the launch. I have tried using highly cambered airfoils optimized for slow gliding, but they tend to degrade the ascent. I wrote a computer program to reproduce the flight of the world record paper airplane to learn what parameters were most important for a long flight.

One of the most important things I learned was that Cdo, zero lift wing read article, is more important in the ascent than it is in the descent. The airfoil optimized for slow gliding is not optimized for zero lift, and produces extra drag during the ascent.

What is needed is an airfoil which produces low drag during slow, high lift flight, but more importantly has low drag during the ascent. I believe a nearly flat, uncambered airfoil does this. Certainly a flat airfoil is ideal for low drag at zero lift, but it can work at higher lift coefficients also. The flat wing at high lift results in a steep pressure gradient near the front of the wing on the upper surface, which likely aids transition to a turbulent boundary layer which is needed for low drag at high lift.

I plan to do more airfoil tests during the spring of '97 to help find the best airfoil for long flight. I have found pitch stability to be important also. The plane not only needs to be stable, but it needs to have just the right amount of stability.

Power Point do physics fly airplanes paper how high level

Pitch stability is controlled by how nose heavy the plane is, and that is controlled by the size and number of folds down the sheet of paper. The flexibility effects apparently only produce a small change in pitching moment, so the stability must be fairly weak to allow a significant change in trim angle of attack. Too little stability results in erratic gliding flight, with frequent stalls as the plane drifts slower than the desired angle of attack. One way to improve gliding stability is to tighten the turn radius. As a plane circles in flight it introduces a pitch rate. Natural pitch damping tends to try to nose the airplane down with positive pitch rate.

As pitch rate increases with angle of attack, so does the nose down pitching moment due to pitch rate, thus providing added pitch stability to source plane. The tighter the circling, the better the stability. A drawback to this scheme is the increased load factor, and degraded gliding performance as the plane circles more tightly.

Many times I set the circle size, by adjusting the rudder deflection, just small enough to keep the plane from porpoising pitching up and down into a stall.

Generally circles less than 20 or 30 feet in diameter noticeably increase sink rate. This represents the lowest how do paper airplanes fly physics of change of potential energy power which is the minimum product of drag times velocity. Generally the minimum sink rate for gliders is just above stall, and that's true for paper airplanes as well. For those interested in the details and math, finding the minimum power required involves taking the equation for powered required, differentiating with respect to velocity, and setting this equal to zero standard calculus procedure for finding the minimum or maximum of a function.

For the world record paper airplane this gives a minimum sink speed of about 2. The weight is determined by the thinnest paper which can withstand the launch throw, which is about 24 pound paper, which is about. The wing span of the world record plane is about 7. I have to be careful when adjusting the elevator deflection for my plane, to trim it near, but not past the stall angle of attack determined by throwing, readjusting, throwing During the fall of '96 I decided to try to design a better airfoil section for my plane to decrease the Cdo.

I used the PROFOIL program see my aeronautical engineering links to design several candidate airfoils. The new airfoil shape seemed to work. Previously only a small fraction of the planes I build really seam to "float", many sink at over 3 or even 4 feet per second for a world record attempt I make about planes over several weeks, and use the few best ones which launch and glide the best. I reasoned that if I could find a better airfoil more info I would not only have a better plane, but one I could make more consistently.

Unfortunately the new airfoil shape degrades launch performance see sect. New airfoil Pressure distribution I have also tried a version of the world record plane which does not have a fuselage, it is a flying wing with no dihedral, but uses the wingtips canted up and out at an angle for the dihedral effect. The idea is to eliminate the "V" shape of the fuselage and use that part of the paper to maximize the wing span to reduce the sink rate. Unfortunately I have not been able to achieve good ascents, with low launch heights as a result.

This modification noticeably affects the flexibility which allows good launches. Another area for study is washout, the relative angle of attack of the tip of the wing compared to the root of the wing. This could improve the span-wise lift distribution which could improve the "e" in the sink rate equation. As the plane is folded, there is a tendency for positive washout, with the wing tips at a higher angle of attack than the root. I have tried to construct test planes with the wings set with negative washout, with the tips at a lower angle of attack than the root.

This is more typical for real airplanes as it promotes a better stall pattern, with the root stalling first. It should also provide a better span lift distribution for reduced induced drag due to lift drag.

Often do how paper fly airplanes physics your community

Initial tests showed degraded launch characteristics, and no noticeable glide improvement. I think I will try for zero washout, as this should provide the lowest drag during the ascent. I have also recently found a report which relates that low aspect ratio wings less than 2 have a tendency to have increased suction peaks at the wing root, which might provide a lift distribution similar to negative washout.

Most have flight times from seconds.

New York, [A good reference] Selig, M. This force is called drag. This pulls air molecules farther apart, which means they put less air pressure on the top of the wing than the bottom. Get a glass of water and take a good look at it, it's density is the mass of the water contained in the area bounded by the glass. How does this affect the plane's flight? So far none has worked as well as the original, but I keep trying. This can be related to Newton's first law stating that in the absence of an external force, a body at rest remains at rest and a body in motion remains in motion. I have tried using highly cambered airfoils optimized for slow gliding, but they tend to degrade the ascent.

One of the goals of my research and testing is to be able to make the "good" planes on a repeatable basis. The best way I know to do this is to understand the physics involved, and then work on solutions. I have found that the physics involved can get quite complex, and it is difficult to get definite answers from my tests. I do think I am making progress, and hope to continue to improve my understanding and ability to consistently make good planes. I do actually try to invent new design to tackle the world record. So far none has worked as well as the original, but I keep trying.

I suspect there are much better designs waiting to be discovered, and no doubt in the future one of these better designs will hold the record. In March of I participated in a BBC paper airplane contest in London, England. The building was huge, but was unheated, with cool rainy conditions outside. Paper airplanes hate humidity. I'm not sure if its due to the relative humidity, or absolute humidity, but generally if its rainy outside, the paper is going to have even worse than normal structural properties. Normally I rely on the resilience of the paper to hold the wings at the proper dihedral angle during gliding flight.

Even on dry days, the paper eventually "fatigues" and is unable to support the root bending moment of the wing, resulting in "floppy" wings with increasing dihedral angles. On humid days I may get only two or three good world record throws from a plane. The problem is that it takes at least 2 or 3 flights to make the proper adjustments to the check this out and elevator for optimum flight times.

Back to the contest, I was having a horrible time trying to get my planes adjusted before the wings fatigued. Going into the last round of the competition I was in third place 15 seconds, the best flight of the day being about 16 seconds. I was extremely lucky to get a My plane design uses the maximum wing span for dry conditions, with many of the competing designs having shorter spans which were less affected by the conditions, allowing them valuable adjustment throws.

The skill of the other contestants was outstanding. Some of the other participants have even subsequently submitted record flight claims to Guinness - so far they have not had their record flights authenticated, but it may only be a matter of time. But I'm not going down without a fight!

Do paper how physics airplanes fly help

I'm still working on my planes. Naturally paper airplane books talk about paper airplane aerodynamics, but usually in a simplistic manner. There are many reference to low speed flight which are applicable to paper airplanes. Here are a few. Mueller, "Experimental Determination of the Laminar Separation Bubble Characteristics of an Airfoil at Low Reynolds Numbers", AIAA, May [Not directly applicable to paper airplanes, but covers some of the wing flow physics, and contains many references] "Proceedings of the Conference on Low Reynolds Number Airfoils" - These conferences have been held several times - I see the Proceedings referenced a lot in low Reynolds number papers.

Books Blackburn, KD and Lammers, JL, "The World Record Paper Airplane Book", Workman, [Why paper airplanes fly, and why they crash] Blackburn, KD and Lammers, JL, "Kids Paper Airplane Book", Workman, [Similar content to 1st book, concerning why paper airplanes fly, more hands-on experiments to demonstrate principles. Also a teachers guide for this book is available from the publisher with more paper airplane information] Hoerner, S. Includes references to low Reynolds number drag throughout] Hoerner, S. New York, [A good reference] Selig, M.

Stokely, publisher, [Dr Selig at the U. There have been several releases of his "Airfoils at Low Speeds", also known as "Soartech", with some info available on the internet].


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