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airplane winglet project

Postby fyucherengineer » Fri Sep 21, 2007 7:45 pm

im a junior in high school in an advanced science program and for my semester research project i was thinking about doing the "winglets in wind tunnels" project on this site.


the only problem is that it says nothing about how to actually make the wing models. should i just carve them out of balsa wood or should i make a frame out of balsa wood and then cover it with some sort of plastic. i was thinking about the frame but im not sure exactly how i would make the curve that one of the winglet designs calls for. also should, in order to measure drag and lift accuratelly, should i make two wings like the two wings on each side of the plane, because i dont think id be able to measure lift accurately if i just had 1 wing on one side of the plane.

any help in this matter would be greatly appreciated.
Im hoping to present this project at regional competition, actually.

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Postby Craig_Bridge » Sat Sep 22, 2007 9:57 am

Sounds like you've chosen a great project area especially if your school or advisor has a wind tunnel with smoke capabilities so you can visualize turbulence.

You need to learn more about the wind tunnel you are going to be using in terms of size and velocities and how laminar the flow is so you can make effective use of the tunnel to make accurate measurements.

If you want to do a great Science Fair Project, before you think too much about how and what to build, you need to carefully formulate a hypthesis (see http://www.sciencebuddies.org/mentoring/project_guide_index.shtml and look at the scientific method). Knowing exactly what you want to compare and what you need to control between samples can greatly simplify what you need to build. It also helps in formulating what you need to control between test samples (weight, surface area, leading wing edge length, attack angle, cross section area, center of gravity, and possibly a whole lot more depending on the specific question).

Measuring drag and lift at wing tips and comparing between two wing tip designs is a measurement challenge. If you add a lot of non-tip surfaces into the mix it significantly increases the need for uniformity between large portions of the models you are attempting to compare wing tip behavior on.

Aeronautical engineering models for this purpose are typically made using CNC (Computer Numerical Control) milling to get the consistency needed.

For the do-it yourself experimenter, you probably need to come up with ways of modeling a smaller section or find ways of sharing pieces like using one basic wing and attaching different winglet sections to it in order to reduce uncontrolled variances.

Part of proving out your test aparatus is going to involve:
1) Whatever you are intending to measure in terms of winglet behaviors is statistically significant with respect to the properties of the base wing. In other words you don't want a base wing with a lot of lift if you are trying to measure the winglet lift contribution.
2) That turbulence at the non-winglet end is minimized or nulled out from your measurements or is far enough away and is consistent for all test samples so that it isn't a statistically significant factor.

Once you have considered what you want to measure and have done some research using the project hints at things to read particularly on turbulence and know what your wind tunnel is capable of, THEN you can figure out how big you wing and winglets need to be and how heavy to make them. Remember, you are NOT building something to actually fly, you are building something to measure some areodynamic property using a specific wind tunnel.

Do some more reading and post back with some wind tunnel information and any questions you have.

Keeping the construction methods simple will significantly speed up the evolution of your project. Unless you teacher or advisor has a LOT of experience and can tell you what sizes and weights can be accurately measured in your wind tunnel, you are going to have to do some crude experiments just to get a feel for the scale of what you need to build in order to make your measurements.

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