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 A1_GOLD
Joined: 5/6/2009
Msg: 86
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How do airplanes fly?Page 3 of 7    (1, 2, 3, 4, 5, 6, 7)

Put simply, an aircraft airfoil accelerates air and deflects it downward. Using Newton's third law of motion, that downward flow causes an upward force on the airfoil-- lift.


Your saying that the air under the wings go down like a rockets exhaust? For every action there is an equal and opposite reaction. That makes sense and would explain the thrust developed by the airplanes engines if they were pointed downwards but how do the wings do that?

I know that the way birds develop upward thrust is by flapping their wings, pushing air down, a third law phenomenon, but airplanes don't do that, flap their wings that is.

I've been looking for wind tunnel evidence of it for years! Something that shows the air deflected downwards under the wing. Could you direct me to an online video source that does please.
 aaamm
Joined: 7/5/2009
Msg: 87
How do airplanes fly?
Posted: 1/1/2010 8:05:13 AM

but airplanes don't do that, flap their wings that is.
Why would the wings need to flap? If the plane is moving forward due to the engines force, this causes the air force to go under the wing pushing the plane up due to the angle of the wing.
 flyguy51
Joined: 8/11/2005
Msg: 89
How do airplanes fly?
Posted: 1/1/2010 12:55:56 PM

Your saying that the air under the wings go down like a rockets exhaust? For every action there is an equal and opposite reaction. That makes sense and would explain the thrust developed by the airplanes engines if they were pointed downwards but how do the wings do that?

Not exactly. I'm saying that the air OVER the wing flows at a downward angle at the trailing edge of the wing. The faster the air moves, the less downward angle it needs to create lift in the amount required. That is why an airplane flying quickly is level to the ground, while the same plane flying slowly (fast/slow relative to that airplane) is tilted up relative to the ground-- or, more accurately, relative to the oncoming air-- i.e. angle of attack.

Why would the wings need to flap? If the plane is moving forward due to the engines force, this causes the air force to go under the wing pushing the plane up due to the angle of the wing.

Close, but it is the air going over, not under, the wing that is lifting the plane.
 aaamm
Joined: 7/5/2009
Msg: 90
How do airplanes fly?
Posted: 1/1/2010 1:04:10 PM

Close, but it is the air going over, not under, the wing that is lifting the plane.
Wellll really isn't it a reaction of both? You know the air below is creating a force as well as the air above the wing. I love to watch hang gliders, wouldn't do it myself because you have to land, but with them, they can almost just jump and catch the thermals. We have a great spot called High Rock near Penn Mar, in case anyone else has heard of it.

But I still think the pixie dust helps.
 flyguy51
Joined: 8/11/2005
Msg: 91
How do airplanes fly?
Posted: 1/1/2010 4:00:34 PM

Wellll really isn't it a reaction of both? You know the air below is creating a force as well as the air above the wing.

Yes, but it isn't a force that is beneficial to lift. I think you are working more along the lines of a parachute or airbrake, where air impacting a surface creates a slowing force. Ideally, a wing would work best if air only flowed over the top, but that cannot happen. It would also work best if it were infinitely long, as drag is created where the upper and lower flows meet at the wingtips.

Using Newton's 3rd law again, the flow under the wing lessens the downwash coming from the top.

Using Bernouli's Principle ("nooo!"), the air flowing underneath lessens the pressure differential being created.
 endlesslift
Joined: 12/31/2009
Msg: 92
How do airplanes fly?
Posted: 1/3/2010 9:47:44 PM
Fly,

Can you explain how a vacuum sucks the wing up (or reduced pressure).

I think this sucking force could be a new force of nature.

Endless
 aaamm
Joined: 7/5/2009
Msg: 95
How do airplanes fly?
Posted: 1/4/2010 11:27:32 AM
See I was always under the impression that pressure, wind turbulence and wind velocity effect the propellers and wings of an aircraft . As air does have a mass, how could it not be considered to be part of the flying process. Without top we have no bottom without bottom we have no top. The forces all figure into the equation. (Yeah, tons of math in physical science. How can science live without math?)
 aaamm
Joined: 7/5/2009
Msg: 99
How do airplanes fly?
Posted: 1/4/2010 5:37:40 PM
^^^^^Thank you.

I think I should be floating...I feel pretty dense at the moment cause I thought I understood flight. I also prefer the lighter parts of this thread where nasty comments aren't being hurled.

Some of you should check out the windmill thread. I still say that Don Quixote is the reason they only have 3 blades. http://forums.plentyoffish.com/datingPosts13587132.aspx No pixie dust involved with them.
 Island home
Joined: 7/5/2009
Msg: 100
How do airplanes fly?
Posted: 1/4/2010 6:34:17 PM
Without top we have no bottom without bottom we have no top

If you have no sides and turn it on it from horizontal to vertical you will have no top and no bottom and then perhaps need to choose which side your on.
Not sure if this helps with flying upside down.
maybe more about flying side on?

Just saying

aaamm
you cheat by floating
when you are denser than air
by walking on sunshine
and you do it so well
 endlesslift
Joined: 12/31/2009
Msg: 103
How do airplanes fly?
Posted: 1/5/2010 10:24:08 AM
NotTooFishy,

That's not buoyancy, that's called a hurricane.
 flyguy51
Joined: 8/11/2005
Msg: 105
How do airplanes fly?
Posted: 1/6/2010 4:43:40 PM
Appreciative, I am admittedly just a relative layman without a degree in aeronautical engineering, so I have the following questions/issues about what you are saying:

The air under the wing is pushing up on it, by pressure above atmospheric pressure

It is my understanding that the flow below the wing is below atmospheric pressure, and the flow above is even farther below atmospheric pressure. To tell you the truth, though, I never thought about where that pressure rates relative to atmospheric.

if the wing is concave below, of has positive angle of attack, then the air deflected by the wing's lower surface adds to the downwash (and the lift).

I didn't think that the boundary layer adheres to a concave surface. I would be interested to see pictorial or textual sources of this happening with a concave wing.

it would be reasonable to say that a speed-change causes a pressure change, a la Bernoulli's effect.

Where so many posters here, and so many books too, are wrong is where they say that, over the wing, Bernoulli's principle is causing the low pressure. No, above the wing, the low pressure is causing the high speed, via Bernoulli's principle, not the other way around.

The claims of these two paragraphs contradict eachother. Regardless, I would be interested in seeing cites that you feel are correct in explaining the true principle.
 ~DREAMS~
Joined: 1/8/2007
Msg: 106
How do airplanes fly?
Posted: 1/6/2010 6:11:23 PM

The claims of these two paragraphs contradict eachother. Regardless, I would be interested in seeing cites that you feel are correct in explaining the true principle.


I think i understand what he is say with that statement...

Go back to thinking in terms of water flow for a moment.

If you had an old jet ski and instead of floating it at the surface you were able to make it safe to submerge it without drowning it in a swiming pool you could likely see the effect.

Now for explanation lets say the output is completely under the water surface.

If you had a 1/4 plexiglass box tube made that is an open box on one end but tapers to round in the front to form a tight seal to the output of the jet ski motor and gassed it then the jet ski would not try to push to the side of the pool underwater very hard. However, If you made the other side identical then it would push through the water because the output whole is the same size as the input whole. The size of the box in the middle does not matter at all... If i understand him i think that is what he was trying to explain.

Same principle works with airplanes that go supersonic. The air is thinner up there but the faster you go the more it acts like water instead of air.

Turning up there in high speeds is very hard to do. The force required just to move the control surfaces is borderline extream.

using that cheap jet ski supersonic wind tunnel basically and different tencile strength fishing line afixing the design to the sides of the box to suspend it in the middle before submirging and starting the jet ski engine can likely allow you to see it in action.

I don't know the exact formula for you to be able to use cause math is not my thing.

In an earlier post of mine i mentioned one of my designs i made shaped like an "H"

normal supersonic shapes have a hard time turning up there because if the roll to turn the air is so thin they lose to much alt to quickly to make turning that way valid. this too can be seen in that water tunnel.

with the H design it allows pressure on all sides so if you roll to turn it does not lose alt as quickly but requires massive force applied to the control surfaces to cause the roll.

Basically using pitch and roll to stear the plane. many of the current supersonic craft out there now use the yaw to turn by altering the thrust on the engines because like i said the force required to adjust control surfaces at those speeds it too great.

get up around mach 7 and things get really crazy ;)

However, if you were to use the extreem pressures generated BY those speed to use to power the control surfaces greater control is possible.

like example... using small inlet holes in the leading edges of the wings that are tapered would increase the pressure of the output to avoid equalization of the pressure. That output could then be connected to a piston like an air piston used to adjust the control surfaces.

Since the pressure is great trying to open and close those control flow inlets would be an issue but if the openings were built like a camera shutter not as much pressure would be needed to open and close them in small bursts. A computer would need to be in control of those though due to the delay between the human brain and physical movement to handle all the adjustments needed to keep the plane stable. that would be a lot of shuttle pulses per second acting upon the various control surfaces to keep the plane from rolling or pitching out of control. yaw could easily be handled by the engines though.

Get up around mach 10+ in the air and the pressure outside of the air craft would likely be similar to the deep parts of the ocean and cause the plane to crush in on itself unless again there were inputs shaped like a funnel to increase the inside pressure of the craft to equalize to keep it from imploding.

Just a few of my thoughts.... Not sure if they are correct but they seem to work with my limited observations and testing i did many years ago when i had more materials available to me due to having a better job.
 A1_GOLD
Joined: 5/6/2009
Msg: 107
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How do airplanes fly?
Posted: 1/7/2010 7:09:51 AM

That's not buoyancy, that's called a hurricane.


Now that's what you call Air Power!

I must thank you all. I had forgotten that once upon a time I had wanted to be a pilot. Absolutely fascinated by Rutan designed home built planes in the 70s. Can't find anything as exciting now as his Quickie (Model 54) or EZ. Sweet stable exciting machines something to make you look forward to a calm Spring or Summer day's outing.

Is there anything as exciting out there now? A little airplane a couple of people can build over the Winter?
 aaamm
Joined: 7/5/2009
Msg: 108
How do airplanes fly?
Posted: 1/7/2010 7:41:01 AM
^^^^^Your post reminded me of the movie Secondhand Lions (2003). What a wonderful movie. There is an airplane in it that the men fly. I won't give anything anyway, cause I think everyone can get something from that movie.

I like the water comparison. When I have flown and had turbulence, it was just like when we were on Lake Erie as a kid in our cabin cruiser, The High Six.

Like I have said before, I enjoy watching people hang glide as well as birds. They ride the thermals, I always feel I see them floating on not under the air.
 ~DREAMS~
Joined: 1/8/2007
Msg: 109
How do airplanes fly?
Posted: 1/7/2010 10:30:43 AM
With my design, pitching up at mach 7 is enough to break through the pressure barrier and escape the air to head out into space.

That means No rocket, No expencive fuel, and no pilot is even needed within the craft to go from take off from the waters surface out into space without simply deflecting off the barrier like the SR-71's ran into for troubles....

basically they screwed up on their choice for the fuel source, take off and landing surface choice, and control surface design. (My opinion at least)

My ship looks like an SR-71 on steroids. A cross between the SR-71 and the fictional ship called "the o'neill" (even though it was designed LONG before that series ever hit TV)

http://upload.wikimedia.org/wikipedia/en/4/48/O%27Neill_class.jpg

Can't show the actull picture of my design though... I am sure you can figure out why
 ~DREAMS~
Joined: 1/8/2007
Msg: 110
How do airplanes fly?
Posted: 1/7/2010 11:09:20 AM
forgot to add this.... hummm what gasious substance is located in the upper atmosphere as well as in space? HUMMMM but using that for fuel would not require needing a huge re-fueling plane or gas stations stops being placed all over the place up there to get things done

Sorry but some of those people working in places like in texas are so smart they are TOO smart for their own good and let their ego's blind them to the most obvious of solutions. the more moving parts you have, the more complex it becomes, the more complex it is means the more prone to failure it is, and failure of even one crucial system or part in any air craft is deadly. Most designers pushing the boundries do not exactly incorporate redundant systems into their designs in order to save weight.
 aaamm
Joined: 7/5/2009
Msg: 114
How do airplanes fly?
Posted: 1/7/2010 6:29:00 PM
25,700 miles per hour is about how fast Superman flies. So he flies twice as fast as he has to, 11,200 mph is what I understand is necessary in lay terms to break our atmosphere. But da planes except for Black hawks (I think I have right plane) doesn't go beyond our atmosphere right? Soooo...this doesn't matter to planes and how they fly right? (And yeah, just books and college physics and math, no degree in either. But love reading the posts and following them.)
 ~DREAMS~
Joined: 1/8/2007
Msg: 115
How do airplanes fly?
Posted: 1/7/2010 9:57:52 PM

Mach 7 isn't fast enough to get into orbit or escape from the Earth's gravity. A low circular orbit requires about 4.9 miles per second. Mach 7 is only roughly 1.4 miles per second. Escape velocity is roughly 7 miles per second.


So saith public released information....

Would not want people to know the "exact" requirements or you just might have every back yard builder cobbling stuff together.

I will give you a little tip that you can take or disregard.

Until you try something yourself never assume what you have read is accurate.

Quickest way to deter anyone from doing anything in life is to impose huge seemingly unreachable limitations within any materials they would have access to that they may be learning from.

basically put... Go mach 7 at 72,000 feet and yank the stick back wait 5.3824 seconds then come back here and tell us where you ended up.

You see sir i know your reply is not accurate because you made a statement like that without even asking the weight of the craft that would be going mach 7.

So how can you sit in front of your computer and tell me what the escape velocity would be for a ship you know not what it weighs to calculate the effect of gravity upon it.

What you gave me is the escape velocity of a huge assed rocket or shuttle weighing thousands of tons. read that from the broshure from the trip to nasa musium?

Some smart people down there. But stick too many smart people in one room and nothing gets done cause everyone wants to work on their own stuff....

PSSST here is a tip i already gave my weight now recalculate and you will see only mach 6.6 was trully needed to get through the pressure bubble.
 ~DREAMS~
Joined: 1/8/2007
Msg: 116
How do airplanes fly?
Posted: 1/7/2010 10:00:25 PM
But da planes except for Black hawks


Blackbird. But the planes are actully blue. The name Blackbird might have come because they were only flown on missions at night but not sure on that part.

I had a thought about rudder control.... on supersonic airframes.

If you look at normal planes you see the part that moves is at the back of the rudder section....

That mean in order for the rudder to be moved in either direction you need a massive force applied at a constant...

Like in jet liners that force is applied by hydralics.

But when i see air craft design i see that whole system as WRONG and flawed and backwards...

Instead of just part of the rudder moving like a boat is how they made it. But why make it like that?

Too much force is required.

Instead move the WHOLE rudder and have the front of the rudder be what moves.. that way all you need for pressure for it to turn would be enough for the rudder to decide if it is moving right or left. after that point you just need a step ratcheting system in place to stop the rudder from flopping all the way left or right.

basically put... the only force needed would be just a nudge and then it would be the job of distance limiters to control how fast and how far the ruddle moves...

Just my opinions. sorry just wanted to add that because i realised i did not explain it in the earlier post.
 A1_GOLD
Joined: 5/6/2009
Msg: 119
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History
How do airplanes fly?
Posted: 1/11/2010 7:58:02 PM
All the discussion of spy planes got me thinking.

James May, a British TV reporter, recently narrated a show called "James May on the Moon". Within the show he boards a U2 'NASA' spyplane and flies in it to 70,000 feet. I've never seen anything quite as beautiful concerning flight. You might look it up on YouTube as "Ride on a U2 spy plane". It puts flying to edge of space in good context.

I've never seen anything like it.
 endlesslift
Joined: 12/31/2009
Msg: 123
How do airplanes fly?
Posted: 1/16/2010 11:31:27 AM
I was just looking at the original post.

The little airplane at http://www.rubber-power.com is rather interesting.

Did you realize that the design of an airfoil for a small air plane such as the rubber-power one is different than for a larger one such as a remote controlled aircraft or even a commercial jet?

The rules change for different sized things.
 endlesslift
Joined: 12/31/2009
Msg: 124
How do airplanes fly?
Posted: 1/16/2010 11:31:58 AM
I mean when you think of it, isn't the wing on that airplane upsidedown?
 ~DREAMS~
Joined: 1/8/2007
Msg: 125
How do airplanes fly?
Posted: 1/16/2010 12:45:46 PM

I mean when you think of it, isn't the wing on that airplane upsidedown?


smartest thing i have seen you post
 ~DREAMS~
Joined: 1/8/2007
Msg: 126
How do airplanes fly?
Posted: 1/16/2010 8:13:40 PM
This one has some EXCELLENT views to see some of the things i was talking about.

http://www.youtube.com/watch?v=yqW5oOskPIM&feature=related
 ~DREAMS~
Joined: 1/8/2007
Msg: 127
How do airplanes fly?
Posted: 1/17/2010 11:12:35 AM
Ok I know there are lots of thoughts and theory's on how airplanes fly going back to the kitty hawk days.

Compression is how planes fly.... Study things with a microscope and you can see as an airplane lifts off the ground the mass of the plane pushes against the molacules in the air.... those bang together and get all excited... those molacules then push back which results in lift....

take a piece of cardboard that is ridgid and wave it in the air.... feel that resistance?

That is the result of the same effect on a much smaller scale.

It has nothing at all to do with air flowing over the wing, it has nothing at all to do with creating vortex cousions. It has everything to do with density of the air molacules within the air....

The denser the air the easier it is for a plane to take off and fly.... the thinner the air the longer that plane has to travel down the run way in order to lift off the ground...

People are sometimes afraid to fly when it is raining or foggy out but those are the best days to fly....

Those are the days that a plane can take off the fastest and climb much steeper angles of attack to achive their target altitude because the air is denser during those times...

because that is the case is why it discredits most other theory's even if they seem to work in the designing of air craft....

It is simply energy at its finest... kinetic energy that is...

When those planes push the air molacules kinetic evergy is created and that results in them pushing back. Due to the shape of the planes and the angles of the wings the planes lift off the ground and fly because using the controls they are basically focusing that push back effect in the direction they wish to go....

That is the principle of flight for the laymans form of understanding... which can easily be seen using water which happens to be what our air is made of....

SEE? not that hard to understand once you think about it, and understand a little bit about how things work at the molecular level. The space between molacules is squishy and does not particulaly care to be pushed so it results in that whole for every action there is an equal and oppisate reaction stuff .... Flight is the by product is all.

It does not matter what shape you use at all.... if you can push air molacules they WILL push back.... Yeah that means even a square box could fly.....

but that might put those aerodynamic specialists out of work because the more streamlined they are making things results in higher forces that are required to achive lift....

Don't believe it????? take a look at some of the BIGGEST airplanes in the world... they are some of the most underpowered planes out there because they have the mass required to push due to their NON streamlined shapes.... while some of the nice slick looking smaller planes have to have bigger engines on them than those heavies because they do not deflect enough air to achive lift without the higher speeds and thrust.

There is the principles of flight according to ~DREAMS~....LMAO feel free to test it all you want.. it works and is valid....EVERYTIME
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