Physics paper airplane Bashny.Net

Being a father is almost graduate from high school, the author of the story was drawn into a funny story with an unexpected ending. It has informative and touching part of the political life. The following discussion focuses on the first person.

Please do not break the theme!





Shortly before the new year, the daughter decided to monitor its own performance and to learn that when the log is full fizichka hindsight, some pointed the extra quads and six-month evaluation of hanging between "5" and "4". You've got to understand that physics in the 11th grade - the subject, to say the non-core, all busy dressuroy for admission and exam scary, but it affects the overall score. Gritting heart of pedagogical reasons I was denied intervention - type figure it out myself. She podsobralas, came to figuring out right there and then rewrote some independent and received a six-month five. All anything, but the teacher asked in dealing with the issue register for a scientific conference, Volga Region (Kazan State University) in the section of "physics" and write any report. Participation of students in this shnyaga is to offset in the annual certification of teachers, and of the type "then certainly the year will close." The teacher can understand normal, in general, agreed.
Podzagruzilsya child, went to the organizing committee, took the rules of participation. Because the girl is quite responsible, I began to think and come up with some theme. Estesstvenno turned for advice to me - the nearest technical intellegentu post-Soviet era. In the Internet found a list of the winners of previous conferences (there give diplomas of three degrees), it is to orientate us, but to no avail. Reports were two varieties, one - "nanofilters innovation in oil," the second - "pictures of the crystals and electronic metronome." To me, the second kind of normal - children should cut toad, not to rub points for government grants, but we have ideas not particularly increased. I had to follow the rules, something like "preferred independent work and experiments.»
We decided that we will do some funny report vivid and funny without zaum and nanotechnology - to cheer the audience, it is enough to participate. Time was a month and a half. Kopipasta was fundamentally unacceptable. After some thought, we decided on the theme - "Physics paper airplane." I once spent his childhood in aircraft modeling, and my daughter loves airplanes, so the subject is more or less close. We had to make a finished practical study of physical focus and, in fact, write performance. Next, I'll post the theses of this work, some of the comments and illustrations / photos. At the end will be the end of history, that is logical. If it is interesting, I will answer the questions already deployed fragments.



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It turned out that the plane of the paper has a tricky stall at the top of the wing, which forms a curved zone, similar to the full aerodynamic profile.

For experiments took three different models.



Model №1. The most common and well-known structures. Typically, most imagine it was her when he hears the term "paper plane".
Model №2. "Boom" or "Spear". A typical model with a sharp angle of the wing and the proposed high speed.
Model №3. The model with high aspect ratio wing. Special construction going on the wide side of the sheet. It is assumed that it has a good aerodynamic data of high aspect ratio wing.
All aircraft were assembled from identical sheets of A4 paper. The weight of each aircraft - 5 grams.

To determine the basic parameters of the simplest experiment has been done - flying paper airplane was fixed camera on the background of wall with applied metric markings. As is known frame interval for video (1/30 of a second), you can easily calculate the rate plan. At the height of fall in the respective frames are glide angle and aerodynamic quality of the aircraft.
The average speed of airplane - 5-6 m / s, which is not in x and little.
Aerodynamic quality - about 8.



To simulate flight conditions, we need a laminar flow at a speed of 8 m / s and the ability to measure the lift force and resistance. The classic way of such studies - wind tunnel. In our case, the situation is simplified by the fact that the airplane itself has a small size and speed and can be directly placed in the pipe limited razmerov.Sledovatelno, we do not interfere with the situation when blown model is significantly different in size from the original, that due to the difference of the Reynolds, It seeks compensation for measurements.
When the pipe section 300x200 mm, flow velocity - 8 m / s, we need a fan with a capacity of at least 1,000 cubic meters / hour. To change the flow rate of the engine speed control is needed, and to measure - anemometer with appropriate accuracy. Speed ​​meter does not have to be digital, it is realistic to do with graduation deflecting plates on the corner or liquid anemometer, which has better accuracy.



Wind tunnel is known for a long time, it was used in the studies still Mozhajskij and Tsiolkovsky and Zhukovsky has elaborated a modern technology experiment that has not changed.
Tabletop wind tunnel has been implemented on the basis of a powerful industrial fan. For fan are mutually perpendicular plate, straightening the flow before it enters the measuring chamber. The windows in the measuring chamber provided with glasses. The bottom wall of the rectangular hole is cut for the holders. Directly in the measuring chamber is installed impeller digital anemometer for measuring the flow rate. The pipe has a slight narrowing of the output for the "backwater" flow that reduces turbulence at the cost of speed reduction. The fan speed is regulated by a simple household electronic controller.



Features tubes were worse than estimated, mainly because of the mismatch performance characteristics of the fan nameplate. Backwater flow also slowed down in the area of ​​measurement of 0.5 m / s. As a result, the maximum speed - slightly higher than 5 m / s, which, however, was sufficient.

The Reynolds number for the tube:
Re = VL? /? = VL /?
V (speed) = 5m / c
L (characteristic) = 250mm = 0, 25m
? (Coefficient (density / vyazskost)) = 0, 000014 m ^ 2 / s
Re = 1, 25/0 = 89 285 000014, 7143

To measure the forces acting on the aircraft used elementary aerodynamic balance with two degrees of freedom on the basis of a pair of electronic jewelry scales with an accuracy of 0.01 grams. The plane was fixed on two racks at the desired angle and is mounted on the first platform scales. Those, in turn, is placed on a movable platform with linkage horizontal force on the second scale.
Measurements have shown that the accuracy is sufficient for basic modes. However, it was difficult to fix the corner, so it's best to develop an appropriate scheme of fixing the markup.



When blowing patterns were measured two main parameters - the resistance force and the lifting force depending on the flow rate at a given angle. It was a family of characteristics with quite realistic values ​​allowing to describe the behavior of each aircraft. The results are summarized in the charts with a further valuation scale relative speed.



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Model №1.
The golden mean. Design best suits the material - paper. The strength of the wings corresponds to the length, the weight distribution is optimal, so well-built aircraft are well aligned and flies smoothly. It is the combination of these qualities and ease of assembly make this design so popular. Speed ​​is less than the second model, but larger than the third. At high speeds, it is already beginning to interfere with a wide tail, before stabilizing model perfectly.
Model №2.
Model worst flight characteristics. Large sweep and short wings are designed to work better at high speeds, which is what happens, but not enough lift force increases and the aircraft really flies like a spear. Moreover, it is stabilized in flight properly.
Model №3.
The representative of "engineering" school - a model specifically conceived with special characteristics. High aspect ratio wing really work better, but the resistance is growing very rapidly - a plane flying slowly and can not tolerate the acceleration. To compensate for the lack of stiffness of the paper used in numerous folds toe wing, which also increases the drag. Nevertheless, the model is very revealing and flies well.

Some results by visualization of vortices
If you add to the flow of the source of the smoke, you can see and photograph the streams envelopes wing. We have had no special smoke generator, we used incense sticks. To increase the contrast of the filter used for processing photos. The flow rate is also reduced because the smoke density was low.
Formation of the flow at the leading edge of the wing.



Turbulent "tail."



It is also possible to investigate flows with short threads, glued on the wing, or a thin probe with a thread at the end.

It is understood that a paper airplane - it is primarily a source of joy and a perfect illustration for the first step in the sky. A similar principle is used in practice hovering just flying squirrels do not have a large national economic significance, at least in our band.



More practical is the likeness of a paper plane "Wing suite" - a suit-wing for parachutists that allows for horizontal flight. By the way, the aerodynamic quality of this suit is less than that of the paper plane - no more than 3.

I came up with the theme, the plan - 70 percent, editing theory, bits of iron, general editing, the plan performance.
It is - the whole theory has collected up to the translation of articles of measure (a very time-consuming, by the way), images / graphics, text books, presentations, reports (there were a lot of questions).

I miss the part where generally considered the problems of analysis and synthesis, allowing to build a reverse sequence - design characteristics of the airplane on the set.



In view of the work we can put on a mind map coloring indicates the performance of tasks. Green color is marked items that are at a satisfactory level, light green - questions that have some limitations, yellow - the area affected, but not developed adequately, red - promising, need further study (funding is welcome).



A month passed quickly - the daughter of digging online, chasing a pipe on the table. Scales kosyachit, airplanes blown away by the theory. The output will get a decent 30 pages of text with pictures and graphs. The work was sent to the Correspondence tour (only a few of thousands of jobs in all sections). A month later, horror of horrors, posted a list of classroom presentations, where our side by side with the rest nanokrokodilami. The child sighed sadly and began to sculpt a presentation to 10 minutes. Immediately expelled reading of - to act, so vividly and intelligently. Before the event organized and run with the timing of the protests. Sleepy morning the speaker with the right sense of "I do not remember and I do not know," drank at KSU.

By the end of the day, I started to worry, no response - not a greeting. There was such a precarious state when you do not understand - a risky joke was successful or not. I do not want to teenager somehow left side is history. It turned out that everything was delayed and its report has fallen by as much as 4 pm. Child sent SMS - "all told the jury laughs." Well, I think, okay, thank you though do not scold. And about an hour later - "diploma of the first degree." That was completely unexpected.

We thought about everything, but against a completely wild pressure and lobbied the participants received the first prize for good, but unformatted job - it is something quite out of the forgotten time. After she had told me that the jury (rather authoritative way, at least QPSK) lightning nailed zombie nanotechnology. Looks like everything is gorged in the scientific community that implicitly put an unspoken barrier obscurantism. It got to the ridiculous - the poor child was reading some wild nauchizmy, but could not say what measures the angle during his experiments. Powerful supervisors paled slightly (but quickly recovered), a mystery to me - why they had to arrange a disgrace, and even by children. As a result, all the prizes were given nice guys with normal living eyes and good themes. The second diploma, for example, get the girl with the model Stirling engine that smartly run it on the chair, change the mode smartly and intelligently commented on any situation. Another diploma was given to the guy who was sitting at the university telescope, and there is something looked out under the supervision of a professor who clearly did not allow any foreign "aid". To me the story inspired some hope. In what is the will of ordinary, normal people to the normal order of things. Not habit of injustice foregone conclusion, and the willingness to efforts to restore it.

The next day, at the ceremony, to the winners went Chairman kommisiya reception and said that all of them ahead of time enrolled in the Physics Department at KSU. If they want to do, you just have to bring the documents out of the competition. This privilege, by the way, really existed once, but now it is officially canceled, as well as additional preferences canceled medalists and olimpiadchikam (except, it seems, the winners of the Russian competition). That is - it was pure initiative of the Academic Council. It is clear that the crisis is now on the physics students and not torn, on the other hand - this is one of the normal faculties with good level yet. Thus, correcting four, the child was in the first row enrolled. Oh, how it will dispose of it - can not imagine, know - otpishu.

A daughter would pull such a job?

She also asked - like Dad, I do not own all done.
My version was. You did very, you know what is written on each page, and to answer any question - yes. You know about the area longer present here and friends - yes. I understand the overall technology scientific experiment from idea to result + side research - yes. Significant work - no doubt. I put forward the work on common grounds without protection - yes. Protection - approx. The jury qualified - without a doubt. Then this is your reward for the conference students.

I - acoustics engineers, a small engineering company in the aviation system engineering ended, was still studying then.

© Lepers MishaRappe

All ... Davolno interesting article, at least I thought so!

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