Potential of Camber Variation in Airfoils for Improved Efficiency

[rocketboy]

Hey everyone,

I'm getting ready to start my IB Extended Essay in Physics, and sent a proposal to my supervisor for a study on the performance of various solid rocket engines. Unfortunately this topic was rejected because a) it involves highly explosive and flammable materials, b) apparently I need more advanced lab equipment and c) it is more like a chemistry topic.

So now I have a HUGE problem. I am supposed to have a topic and introduction and outline finished, and I don't even have a topic!

I was wondering if anyone here had any ideas for a physics topic that provides a problem which I would then come up with a hypothesis for, and then prove through experimentation. It also has to be outside of the high-school Physics curriculum, so I was thinking perhaps something on fluid mechanics or thermodynamics, since they are courses that I will need to take in aerospace engineering at university anyway.

Thanks SO much everyone!

-Jon

 

[NateTG]

You could look into the mpemba effect (hotter water sometimes freezes faster than cooler water). There's actually a whole thread on science project ideas that you should look at.

 

[rocketboy]

That sounds cool. I've browsed through the thread on science fair projects but most of them seem too...well, they don't seem in-depth enough for the kind of study I'm doing. It has to be between 3500 and 4000 words so it's fairly in-depth.

 

[NateTG]

That sounds cool. I've browsed through the thread on science fair projects but most of them seem too...well, they don't seem in-depth enough for the kind of study I'm doing. It has to be between 3500 and 4000 words so it's fairly in-depth.

Depth isn't about what you do, but about how you do it.

Let's see, my mother is strangely fascinated by the behavior of carbonated liquids when the seal on the bottle is cracked. As long as there isn't overflow, the fizzing occurs in waves. (I suspect this occurs because the liquid is reacting to the vapor pressure in the gas reservoir in the top of the bottle. If you have a seltzer bottle, you could look into modeling that behavior, and testing it. This would require very little in the way of equipment.)

If you'd like to do some more engineering-oriented stuff, you could look into nozzle characteristics for $CO_2$ rockets but that would probably involve using a lathe. You could test dimple patterns on the sides of bycicle wheels, or on boat hulls for that matter. Alternatively, you might look into the effects of spoke shape on aerodynamics. You could try bubbling air underneath a boat, and seeing if it reduces the friction. (I have no idea how much literature there is on this stuff.)

 

[FredGarvin]

You could change it from the solid propellant part of the rocket engine to the nozzle configurations used. I am positive you could fill up 4000 pages let alone 4000 words.

 

[EnumaElish]

"Optimal conditions" during atmospheric re-entry, descend & deceleration in relation to:
1. materials used
2. module shape, e.g. pointy nose vs. UFO-shaped (oval)
3. velocity
4. angle
5. braking mechanisms
6. other miscellaneous aspects (please specify): ___, ___, ___ and ___.

You could concentrate on anyone aspect or look at multiple aspects and how they interact. Some ground-breaking ideas come from basic obsrevations. The final shape of http://en.wikipedia.org/wiki/Image:SpaceShipOne_ground.jpg . If that's someone's science project, all they'd need is a badminton ball and racket. (Bringing a partner would be optional.)

 

[ohwilleke]

Your advisors did you a favor. I recall once trying to do a presentation on oil lamps for school and only realizing after parental intervention that I had designed not an oil lamp but a Molatov cocktail.

How about studying how the roughness of a wing affects the turbulence patterns it creates. You could do it pretty well with a videocamera, a whiteboard to use as a backdrop, a fan, a model glider, a pole and base to put the glider on, something to generate smoke with (like a tin can with newspaper burning in it), a well ventillated room, and various materials to cover the glider wing with (stickers, taped pieces of paper, sand paper, smooth aluminum foil, rough aluminum foil, etc.). It is an active area of research in aerodynamics right now so there is plenty of literature on the topic.

 

[neurocomp2003]

particle physics? planetary creation.
mmm and if you know anything about programming...fast physics-based simulations in 3D/game environments.

 

[CaptainQuaser]

I personally like kinematics, I did a trebuche in high school, very fun, and there is a lot of physics to play with, may be above your head for the time being though? Rotational dynamics is fun

 

[rocketboy]

Wow, thank you all so much for your help so far. Every single word put forth thus far has helped me in some way or another. I am going to keep looking deeper into these topics and discuss them with my parents and supervisor. I will certainly keep you all posted on what's happening, and more ideas are ALWAYS welcome!

Wow, I can't get over how much help/support you guys provided me with in such a short time period! Thanks again! This has taken a lot of pressure off my back just having these ideas thrown around. (By thrown I mean gently tossed.)

-Jon

 

[rocketboy]

Ok, I've decided to go with the aerodynamics suggestion, and so far I've typed up the outline for the experiment...kind of a proposal to my supervisor. What I'm going to do is make my own wind tunnel out of plexi-glass and the whiteboard for one side, and then at one end I'll have a leaf-blower for the wind source. Should work pretty well. I figure I'll put grooves in the sides of the tunnel for the wing to sit in, with ball bearings so that when the air flows across the wing, the wing is able to rise in the grooves.

The only question is, how am I going to attach different materials to the wing while maintaining its' shape? I don't want to have to glue them, because then I would need a new wing for each material.

Thanks everyone!
-Jon

 

[FredGarvin]

In a perfect world, you should use a different model for every different scenario.

Have you given any thought to introducing a smoke wand so you can visualize the streamlines?

 

[NateTG]

The only question is, how am I going to attach different materials to the wing while maintaining its' shape? I don't want to have to glue them, because then I would need a new wing for each material.

If you're only using the surface, a vacuum could work very nicely.

 

[jubs]

ON a side note you might need to look into modeling and similtitude if you plan on applying it on a large scale. It is not too difficult of a concept from the early stages of it that I have studied.

 

[rocketboy]

In a perfect world, you should use a different model for every different scenario.

Have you given any thought to introducing a smoke wand so you can visualize the streamlines?

I would like to use a different model for every different scenario but I also want to keep the cost to a minimum.

Yes my good friend ohwilleke proposed the idea and suggested the smoke wand above, I love the idea!

If you're only using the surface, a vacuum could work very nicely.

You mean, a vacuum inside the wing that sucks the material to it? If so that's a really interesting idea, I'll look into that, thanks.

ON a side note you might need to look into modeling and similtitude if you plan on applying it on a large scale. It is not too difficult of a concept from the early stages of it that I have studied.

Thanks, I'll check it out.

 

[Danger]

The only question is, how am I going to attach different materials to the wing while maintaining its' shape?

If the school is paying for the materials, I would recommend that you go with Fred's suggestion since it's the most professional approach. You could make a mould of your wing design and cast several versions out of fibreglas, expansive foam insulation, acrylic resin or similar.
If that's not practical, maybe you can obtain the kind of adhesive used in Post-It notes.
Finally, as Nate pointed out, drilling an array of 1/2mm holes all over the surface, making the rest of it airtight, and introducing a vacuum source from the 'root' end of the wing would work nicely. We used the same technique in screen printing to maintain the substrate in position and it's very effective. Perhaps you could even tap the intake side of your leaf-blower as a vacuum source. (Make sure that all of the vacuum holes are covered, because any leakage decreases the effectiveness severely.)

 

[EnumaElish]

You shouldn't assume that an interchangeable wing is always going to be the cheaper option. If you concentrate on two materials (or designs) only, you need to build only two permanent wings. As you increase the number of different wings that you want to test, an interchangeable wing might become cheaper.

 

[FredGarvin]

I guess you should clarify one thing that you may be looking for. Are you going to be taking static pressure measurements on the surface of the airfoils? If all you are interested in is the streamlines and possibly location of seperation, etc... then you could get away with a kind of wrap around the shape. I would only be worried about having protuberances in the airflow that could give you some headaches. If you are going to be making pressure measurements then I would say that the only way to do it properly is to make a new one for every material.

 

[rocketboy]

Ok, for the past few days I have been doing research so that I can narrow my topic down a bit. I have come up with another idea for my essay, and was wondering what you guys thought of it...in other words, do you think it would make a good extended essay?

The idea is to look into how wings with different aspect-ratios (ie fighter wing vs glider wing) and comparing the amount of lift that each type create at various speeds. To do this, I would build my wind tunnel, and then put the wing/model on the end of a see-saw-type device, with a scale at the other end, so that when the model lifts up, it causes the other end of the see-saw to go down, either pulling on an accurate scale, or pushing down on one. I would investigate the wings at various wind speeds, and learning how the aspect-ratio of a wing's design affects lift, and thus how the wing is designed according to its purpose.

What do you think? Questions? Comments? I'd be glad to hear them!

Thanks everyone,
-Jon

 

[FredGarvin]

Aspect ratio is not going to be the leading reason for lift in airfoils. The airfoil shape itself will be the main factor there. I am sure aspect ratio will play a bit of a role, but I suspect not as much as you may think. The thing that a high aspect ratio wing gets you is higher efficiency especially at higher altitudes. Tip losses are less drastic on a longer wing. You may run into some problems trying to make a wind tunnel big enough to handle a long wing as well. Also remember that a long wing will deflect a lot. Do you have a way to overcome that and get a true reading on your scale?

However, it sounds like a pretty good idea to study. If you were looking at possible options, you could replace "aspect ratio" with varying camber in the airfoil in stead. That may be a bit easier to test and manufacture. Just a suggestion. You are doing well with your line of reasoning. Keep it up.