[7DeltaLima]

My daughter is in her first year of teaching second grade and she's wanting to do a short blurb on airplanes, building, how they fly, etc. Unfortunately, she has no clue other than she was in and out of the house "doing" high school a few years ago when I was building the 7A...

I would love to go help her with this in person but her first teaching job moved her from here in Iowa to the big town of San Antonio. Anyway, to keep a short story short, I've sent her some pics and video of the first flight but I'd like to provide her some material to help her out.

Thought someone out there may have some material that they use for ground school/explanation for Young Eagles that they would share so I could share.

Thanks in advance,
Doug

 

[L.Adamson]

One thing for sure, is that it's still "theory", so theory of flight, is certainly a good title!

If I was to give a presentation, I'd have to explain several principals, and then the fact, that there is still no final agreement or exact science after 100 plus years. Newton, Bernoulli , low pressure, high pressure, vacuum, down wash, and several other ideas add up to different versions of why planes fly.

L.Adamson

 

[Captain_John]

Check out this zip file from the www.youngeagles.org website:

http://www.youngeagles.com/voluntee...e - Car to Airplane Animation Zipped File.zip

When it is downloaded you can present the concepts to the children on a projector.

If I were introducing this curriculum, I would have the kids make paper airplanes and use them as manipulatives to aid in instruction.

CJ

 

[Coinneach]

The theory of flight is waaaay advanced for most second-graders. Tell her to keep it simple: "These are the wings, just like on a bird, they're what keeps the airplane in the air." Stuff like that is far more likely to hold their attention than discussions of lift/drag/thrust/weight.

 

[Captain_John]

That ought to take about a MINUTE!



With a group of kids that age, you need to dwell in minutia and keep it interesting. Manipulatives go a long way. The paper airplanes and a household fan will illustrate lift for them.

Basically, they need to play.

Have her email Steve Buss from the EAA. He may have some more stuff!

CJ

 

[pierre smith]

Good advice so far

I've had the opportunity to speak to kids about airplanes. A neat attention-getter is to ask if they've ever stuck their hand out of the window of their Dad's car going down the road, like this....then extend your arm with your palm parallel to the ground. Tilt your hand up a little and make it rise and tell them to try it next time.......the theory of lift...easily 'splained.

Regards,

 

[gbrasch]

wrightflight.org

You might try these folks: http://wrightflight.org/ I have flown kids for them, and they have a program they teach to kids in school, around 5th grade. Then the kids go up for a pretty good flight. They may be able to help.

 

[rfinch]

the fact, that there is still no final agreement or exact science after 100 plus years.

Utter nonsense. The Navier-Stokes equations fully explain the dynamics of fluids with a few esoteric exceptions unimportant to flight.

It's easy to explain flight to 2nd graders if one is willing to leave things a bit fuzzy. To stay in the air, an airplane must push down on air to hold up the weight of the airplane. Most kids have stuck their hand out the window of a car and felt the air resistance. An airplane's wing does the same thing, but moves air downward, keeping the airplane up.

 

[cytoxin]

is it theory or law

Utter nonsense. The Navier-Stokes equations fully explain the dynamics of fluids with a few esoteric exceptions unimportant to flight.

It's easy to explain flight to 2nd graders if one is willing to leave things a bit fuzzy. To stay in the air, an airplane must push down on air to hold up the weight of the airplane. Most kids have stuck their hand out the window of a car and felt the air resistance. An airplane's wing does the same thing, but moves air downward, keeping the airplane up.

if it was as you say, wouldnt it be called the laws of flight?

synonyms hypothesis theory law mean a formula derived by inference from scientific data that explains a principle operating in nature.


hypothesis implies insufficient evidence to provide more than a tentative explanation <a hypothesis explaining the extinction of the dinosaurs>.


theory implies a greater range of evidence and greater likelihood of truth <the theory of evolution>.

law implies a statement of order and relation in nature that has been found to be invariable under the same conditions <the law of gravitation>.

someone please explain to me how a wing flys off the bottom surface when a little bit of frost on the top kills its lift while the bottom is still clean.

 

[SvingenB]

It is all theories, mathematical relations that fits with observations. There is no "truth" or "law", only logical abstractions causing similar abstract results as observed by real measurements.

The Navier Stokes Equations (NS), can actually never be prooved right even if they should be 100% correct, because they are inherently chaotic, as is the nature of aerodynamics. Statistics shows they are very correct on larger scales (for most practical purposes like airplanes), but when going with a "microscope" on the finest details in turbulent flow, one configuration causes an infinite number of different results. The same is also true when measuring real turbulent flow. It is actually a paradox, the NS eq are probably one of the most exact and detailed set of equations ever made, so exact that they even model the chaos of nature even when chaos starts and when it stops, but how can you prove anything when it is chaotic?

Regarding 2'nd graders, I think they understand that airplanes needs wings like birds, and they need speed. But since airplanes cannot flap their wings they have to use engines to get enough speed.

 

[Bugsy]

2 Requirements to fly

Tell her that an Air Force Colonel says that flight requires only two things:

Airspeed and Money

with enough of both we can get anything airborne!

 

[Ted Johns]

if it was as you say, wouldnt it be called the laws of flight?

synonyms hypothesis theory law mean a formula derived by inference from scientific data that explains a principle operating in nature.


hypothesis implies insufficient evidence to provide more than a tentative explanation <a hypothesis explaining the extinction of the dinosaurs>.


theory implies a greater range of evidence and greater likelihood of truth <the theory of evolution>.

law implies a statement of order and relation in nature that has been found to be invariable under the same conditions <the law of gravitation>.

someone please explain to me how a wing flys off the bottom surface when a little bit of frost on the top kills its lift while the bottom is still clean.

Well, powered flight is a fact, I've done it.

What we are quibbling about is exactly how it works. I tend to agree with Ralph, the science is very solid. Remaining theoretical discussions are at a level of minutia far below what any of us need care about.

There is both a theory and a law of gravity. We know what gravity does, but we don't know exactly how it does it. We could have both a theory and a law of flight, but scientists don't tend to bother with such distinctions for anything other than first principles.

Regarding frost on the wing:
Most wings are designed to take advantage of Bernoulli's principle, as well as Newton's. That is, the curved upper surface causes a partial vacuum to form above it, causing the airflow above it to be deflected downward, thus enhancing lift. Of course, the bottom of the wing deflects the air downward directly. When there is frost on the upper wing surface, the Bernoulli effect is not as strong, and the stall speed is increased. One could still fly the plane, but it would no longer fly according to the POH. Aircraft have flown with a ton of crusty ice on the wing, they have also stalled on short final as a result!

Symmetrical wings for aerobatic craft don't get much of a boost from Mr. Bernoulli, and tend to have a higher stall speed relative to the wing area loading as a result.

Here's a really good website for laymans (the only kind I understand) aerodynamics: www.av8n.com

PS: I doubt the second graders are ready for that website, but a 2nd grade teacher could easily glean some interesting tidbits for the students from it.

T.J.

 

[Alex]

Bernoulli is an Equal Opportunity Theory

Most wings are designed to take advantage of Bernoulli's principle, as well as Newton's. That is, the curved upper surface causes a partial vacuum to form above it, causing the airflow above it to be deflected downward, thus enhancing lift. Of course, the bottom of the wing deflects the air downward directly. When there is frost on the upper wing surface, the Bernoulli effect is not as strong, and the stall speed is increased. One could still fly the plane, but it would no longer fly according to the POH. Aircraft have flown with a ton of crusty ice on the wing, they have also stalled on short final as a result!

Symmetrical wings for aerobatic craft don't get much of a boost from Mr. Bernoulli, and tend to have a higher stall speed relative to the wing area loading as a result.

Bernoulli's principle is just as active no matter what airfoil you're using. The problem with frost on the upper surface is that the upper surface of an airfoil at a positive lift coefficient has a strong negative pressure gradient. What that means is that the air is decelerating over the back of the upper surface. This doesn't have anything to do with whether the upper surface is more curved than the lower surface (camber). Because of this negative pressure gradient, it is more prone to boundary layer thickening and flow separation (stall) due to roughness. If you were flying inverted, the bottom (now upper) surface of the wing would be more sensitive.

 

[Ted Johns]

Yup

Bernoulli's principle is just as active no matter what airfoil you're using. The problem with frost on the upper surface is that the upper surface of an airfoil at a positive lift coefficient has a strong negative pressure gradient. What that means is that the air is decelerating over the back of the upper surface. This doesn't have anything to do with whether the upper surface is more curved than the lower surface (camber). Because of this negative pressure gradient, it is more prone to boundary layer thickening and flow separation (stall) due to roughness. If you were flying inverted, the bottom (now upper) surface of the wing would be more sensitive.

Agreed. I could have emphasized that the camber on a typical wing enhances the always present Bernoulli effect, at a given angle of attack.

I didn't specify why frost on the upper wing reduces the Bernoulli effect, but I agree that the reason is flow separation. When the boundary layer tears away, the area of negative pressure is decreased.

 

[pczar3]

Some help from NASA supported site

Here is a NASA hosted site that has a variety of information at a variety of levels. Your daughter could probably adapt some of what is here and perhaps do a few of the simple demonstration experiments. Hope this helps.

http://www.allstar.fiu.edu/AERO/princ1.htm

Paul
pczar3
N694BP reserved

 

[7DeltaLima]

Thanks....

.... for the input folks. Don't know how I missed the car/plane link on EAA YE site. I'll pass the info on to the daughter.

Doug
working on the 10...QB this time...

 

[Captain_John]

You are welcome!

Simple stuff and something the kids can grasp.

It is what I would do.

Wish her well from a fellow teacher!

CJ

 

[Alex]

Common Misconceptions

This is from the site:
http://www.allstar.fiu.edu/AERO/fltmidfly.htm

The special shape of the airplane wing (airfoil) is designed so that air flowing over it will have to travel a greater distance faster, resulting in a lower pressure area

This is the common explanation that always bugs me, because it is simply not true! It is true that an airfoil at a positive angle of attack will cause a flow pattern in which the air on top is moving faster, but it is not because of the camber of the airfoil that this happens (i.e. the usual flat bottom curved top explanation is incorrect). Camber changes the lift coefficient at zero geometric angle of attack, and it increases the maximum lift coefficient, and it can improve stall performance, but it is not the reason why airfoils are capable of producing lift.

Once the familiar flow pattern is established, the following characteristics result:

1) The air on top is moving faster than on the bottom
2) The air on top is at a lower pressure than on the bottom
3) The air is given a downward impulse
4) The wing produces lift

None of these is more important than the others, they're all characteristics of the same phenomenon. But I think the important fundamental question that is missed in all of these discussions is:

"why does the air flow about a wing at angle of attack in the way that it does?"

The answer it turns out is that the sharp trailing edge enforces the location of the rear stagnation point. Once this stagnation point is established, conservation of mass and conservation of energy are sufficient to establish the familiar flow pattern around the airfoil. In aerodynamic analysis, this called the Kutta condition. If the Kutta condition is neglected in an inviscid fluid analysis, then an airfoil will produce no lift.

The Kutta condition is actually a viscous phenomenon. If the trailing edge is sufficiently sharp, then the inertial forces of the air trying to get around that corner ensure that the flow must separate there.