How Airplanes Fly ?
- Thread starter KKArioKA
- Start date
Pilot-294
Senior Member
how jet propulsion works
jet engines and turboprops are easy enough to understand.
a couple things to understand first (all very simple things)
air forced at the same pressure from a larger sized tube into a smaller sized tube will flow faster I.E. fom the top of a funnel to the bottom, if you push the air at 5psi it will move at (for example's sake) 5 mph at the top and 10 mph at the bottom. this is because the air has to flow thru the whole funnel at the same pressure and the air cant just dissapear. so instead of building pressure, its easier for the air to flow thru the tube faster as it shrinks.
and hot air expands
a jet engine is comprised of 3-4 sections depending on the make. the turbines at the front, the combustion chamber in the middle, and the down tube and nozzle at the back (exhaust port or whatever you wish to call it)
and SOME not all jets have afterburners. basically an extra combustion chamber
the turbines are a set of fans that as you advance from front to back produce more and more thrust. this forces the air to compress more and more as it makes its way to the combustion chamber.
once the air makes the cumbustion chamber, it is already at a fairly high pressure. it is optimized to make as much thrust as possible once it is mixed with fuel and lit. more air=more O2=hotter fire. it is mixed with fuel at the front of the combustion chamber, lit on fire, and as it expands its forced out the back. at the rear of the combustion chamber there is one more turbine that uses the thrust from the engine itself to spin the front turbines once its started. more fuel is added to make the engine spin faster, less is slower.
next stage is the afterburner if the engine has one. basically more fuel is added to the exhaust (which is not completely burned and still has good air) and is lit again which adds more thrust.
the down tube is basically a smoothe tapered tube that gets skinnier as it goes towards the end. Since as explained air will move faster as it moves to the end of a tapered tube, this increases thrust. Some jets have nozzles at the end that increase and decrease the size of the opening. Adding or subtracting thrust. And some have thrust vectoring that basically forces the thrust in different directions to maneuver the airplane better along with its standard control surfaces.
Some thrust vectoring like in the harrier jump jet can be used to attain vertical takeoff and landing VTOL and short takeoff and landing STOL
I hope this answers your question well!
No pic from me of an engine I'm on my iPhone, I'll get one Monday unless someone else I feeling frisky! Lol
Hope I got everything right for ya!
jet engines and turboprops are easy enough to understand.
a couple things to understand first (all very simple things)
air forced at the same pressure from a larger sized tube into a smaller sized tube will flow faster I.E. fom the top of a funnel to the bottom, if you push the air at 5psi it will move at (for example's sake) 5 mph at the top and 10 mph at the bottom. this is because the air has to flow thru the whole funnel at the same pressure and the air cant just dissapear. so instead of building pressure, its easier for the air to flow thru the tube faster as it shrinks.
and hot air expands
a jet engine is comprised of 3-4 sections depending on the make. the turbines at the front, the combustion chamber in the middle, and the down tube and nozzle at the back (exhaust port or whatever you wish to call it)
and SOME not all jets have afterburners. basically an extra combustion chamber
the turbines are a set of fans that as you advance from front to back produce more and more thrust. this forces the air to compress more and more as it makes its way to the combustion chamber.
once the air makes the cumbustion chamber, it is already at a fairly high pressure. it is optimized to make as much thrust as possible once it is mixed with fuel and lit. more air=more O2=hotter fire. it is mixed with fuel at the front of the combustion chamber, lit on fire, and as it expands its forced out the back. at the rear of the combustion chamber there is one more turbine that uses the thrust from the engine itself to spin the front turbines once its started. more fuel is added to make the engine spin faster, less is slower.
next stage is the afterburner if the engine has one. basically more fuel is added to the exhaust (which is not completely burned and still has good air) and is lit again which adds more thrust.
the down tube is basically a smoothe tapered tube that gets skinnier as it goes towards the end. Since as explained air will move faster as it moves to the end of a tapered tube, this increases thrust. Some jets have nozzles at the end that increase and decrease the size of the opening. Adding or subtracting thrust. And some have thrust vectoring that basically forces the thrust in different directions to maneuver the airplane better along with its standard control surfaces.
Some thrust vectoring like in the harrier jump jet can be used to attain vertical takeoff and landing VTOL and short takeoff and landing STOL
I hope this answers your question well!
No pic from me of an engine I'm on my iPhone, I'll get one Monday unless someone else I feeling frisky! Lol
Hope I got everything right for ya!
Let me take a shot at turbofan vs jet engine. I may be horribly wrong, but that never stops me!
A jet engine generates thrust by the compression of air through the turbine blades and ignition of an air-fuel mixture in the rear portions of the turbine train. The energy produced by combustion is used to both turn the turbine blades ahead of the area of combustion and to provide thrust for the jet by pushing it forward.
And now that I typed this, I see P-294 has basically said the same thing in much more detail!
A turbojet, as found on many large jet aircraft, uses the combustion to drive a large turbofan to pull the airplane forward, much like a propeller. As P-294 said, the thrust generated by a turbofan
A jet engine generates thrust by the compression of air through the turbine blades and ignition of an air-fuel mixture in the rear portions of the turbine train. The energy produced by combustion is used to both turn the turbine blades ahead of the area of combustion and to provide thrust for the jet by pushing it forward.
And now that I typed this, I see P-294 has basically said the same thing in much more detail!
A turbojet, as found on many large jet aircraft, uses the combustion to drive a large turbofan to pull the airplane forward, much like a propeller. As P-294 said, the thrust generated by a turbofan
Pilot-294
Senior Member
Pilot-294
Senior Member
so here are a few quick an easies that i figured i would tackle in my boredom today since they where posted in the thread as would be covered.
- Flap
flaps are extensions on the trailing edge of a plane's wing as they extend they do a couple of things. they add length to the top of a wing and that increases the low pressure zone above the wing. it adds drag to the bottom of the wing, and this does 2 things, it slows down the air underneath creating a larger high pressure zone, and that drag slows the airplane. this basically lets an airplane fly at speeds lower than stall speed and it will slow an aircraft down as needed. a plane will generally land with full flaps which allows the slowest landing speed possible. and a plane will take off with some flap. not enough flap to create tons of drag, but enough to create lift and take off faster.
- Stall
a stall is really simple, as formerly explained, lift is the force that keeps an airplane in the air and "lifts" the plane straight up. generally, the faster a plane flies, the more lift is attained. lift is opposite weight. drop something heavy and wingless (an apple) and you understand what weight does to an object without lift.
understanding this; a stall is what happens when a plane slows down so much that the lift created cannot compete with the weight of the plane. and the plane drops. when this happens it is best to nose down slightly, and increase throttle. this will add airspeed to your plane and lift and will generally counter your stall. unless your plane has spun.
- Spin (not on the list but while we are talking stall)
a spin is where one wing becomes more stalled than the other wing, this makes the airplane not only drop, but to spin in the direction of the stalled wing.
note that NOT all airplanes are recoverable in a stall. some planes just can't do it, and some are too close to the ground.
once you spin there may be a few different ways to recover. but this is the way my flight instructor told me to do it
acronym PRAY
P: Power off, don't shut down, but idle the motor
R: Rudder opposite, if your spinning left, yaw HARD right. spin right, yaw left.
A: ailerons neutral, just the way it sounds, center the stick.
Y: Yoke neutral, meaning your elevator. center the stick.
PRAY your high enough to recover
PRAY your aircraft is recoverable
PRAY you don't spin (unless you want to and your good enough to)
PRAY God likes you, cus when you hit the ground, the next thing you see will count on it.
by PRAYing you will drop your nose, increase airspeed, and counter the yaw of the spin. and hopefully be able to return to level and controlled flight
- Ascend rate / Descend rate
basically exactly the way it sounds. it is the rate at which an aircraft is climbing or descending. by ascending you gain altitude. by descending you lose altitude. normally measured in feet gained/lost : feet travelled.
your airplane is climbing and for every 20 feet it flies foreword it gains 3 feet. glide rate is +3:20 or if it descends at these same rates, drops 3 feet every 20 feet its rate is -3:20
just a couple of ideas explained to expand the topic.
- Flap
flaps are extensions on the trailing edge of a plane's wing as they extend they do a couple of things. they add length to the top of a wing and that increases the low pressure zone above the wing. it adds drag to the bottom of the wing, and this does 2 things, it slows down the air underneath creating a larger high pressure zone, and that drag slows the airplane. this basically lets an airplane fly at speeds lower than stall speed and it will slow an aircraft down as needed. a plane will generally land with full flaps which allows the slowest landing speed possible. and a plane will take off with some flap. not enough flap to create tons of drag, but enough to create lift and take off faster.
- Stall
a stall is really simple, as formerly explained, lift is the force that keeps an airplane in the air and "lifts" the plane straight up. generally, the faster a plane flies, the more lift is attained. lift is opposite weight. drop something heavy and wingless (an apple) and you understand what weight does to an object without lift.
understanding this; a stall is what happens when a plane slows down so much that the lift created cannot compete with the weight of the plane. and the plane drops. when this happens it is best to nose down slightly, and increase throttle. this will add airspeed to your plane and lift and will generally counter your stall. unless your plane has spun.
- Spin (not on the list but while we are talking stall)
a spin is where one wing becomes more stalled than the other wing, this makes the airplane not only drop, but to spin in the direction of the stalled wing.
note that NOT all airplanes are recoverable in a stall. some planes just can't do it, and some are too close to the ground.
once you spin there may be a few different ways to recover. but this is the way my flight instructor told me to do it
acronym PRAY
P: Power off, don't shut down, but idle the motor
R: Rudder opposite, if your spinning left, yaw HARD right. spin right, yaw left.
A: ailerons neutral, just the way it sounds, center the stick.
Y: Yoke neutral, meaning your elevator. center the stick.
PRAY your high enough to recover
PRAY your aircraft is recoverable
PRAY you don't spin (unless you want to and your good enough to)
PRAY God likes you, cus when you hit the ground, the next thing you see will count on it.
by PRAYing you will drop your nose, increase airspeed, and counter the yaw of the spin. and hopefully be able to return to level and controlled flight
- Ascend rate / Descend rate
basically exactly the way it sounds. it is the rate at which an aircraft is climbing or descending. by ascending you gain altitude. by descending you lose altitude. normally measured in feet gained/lost : feet travelled.
your airplane is climbing and for every 20 feet it flies foreword it gains 3 feet. glide rate is +3:20 or if it descends at these same rates, drops 3 feet every 20 feet its rate is -3:20
just a couple of ideas explained to expand the topic.
teflyer
Full Circle
Nice explanation! Really like the acronym. Very useful!
On flaps, doesn't some of the lift come from the airflow being directed down by the flaps?
Also, how do you know a wing is stalling in a windtunnel? I see these videos on airfoils in windtunnels and they increase the angle of attack until they reach a stall point and wind vortices from the wing are going wild. Can you determine the stall point by looking at how the air moves around the airfoil?
On flaps, doesn't some of the lift come from the airflow being directed down by the flaps?
Also, how do you know a wing is stalling in a windtunnel? I see these videos on airfoils in windtunnels and they increase the angle of attack until they reach a stall point and wind vortices from the wing are going wild. Can you determine the stall point by looking at how the air moves around the airfoil?
Pilot-294
Senior Member
some of the lift may come from a downward force but in essence the flaps really change not only the shape of the airfoil, but the angle of attack as well. so both ways would be correct in theory. try to think of flaps and ailerons changing the overall angle of attack to change lift and cause movement. once the trailing edge of an airfoil is moved down and out, the chord length changes and follows the flap down as well. but it remains stationary at the front unless slats are involved, but lets omit those until later. so basically the wing chord changes in angle and length where the flap extends and changes the shape of the wing itself.
this is my understanding of the process anyhow.
and about the wind tunnel? the wing is mounted on pressure sensors to measure lift attained. they then calculate how much lift is necessary to fly the craft (or wing itself) and compare (could be as simple as how heavy the said wing is). if lift is less than weight set for the test. a stall is achieved.
this is my understanding of the process anyhow.
and about the wind tunnel? the wing is mounted on pressure sensors to measure lift attained. they then calculate how much lift is necessary to fly the craft (or wing itself) and compare (could be as simple as how heavy the said wing is). if lift is less than weight set for the test. a stall is achieved.
Pilot-294
Senior Member
I'm sorry I havnt been too active on this thread lately, I have been busy between my scratch build and keeping my sanity before I leave for BMT idk when I'll get to helping on this thread again as my sanity is questionable at best haha :black_eyed:
I'm terribly sorry I can't be much help at the moment... But if I do get the chance to I'll help out where I can
I'm terribly sorry I can't be much help at the moment... But if I do get the chance to I'll help out where I can
Basically what I think a fan-wing does is to move the air on top of the wing to under the wing. Since it's taking air away from the top of the wing, pressure is reduced; and since it's putting the air under the wing it increases pressure. The pressure difference creates lift. I think that's how it works...
teflyer
Full Circle
I found this:
http://www.fanwing.com/desc.htm
I thought the rotor forced air on the top of the wing so that the air on top is moving even faster than on the bottom and the pressure difference would be higher. I think that is mechanically induced circulation effect.
The website claims that it is very fuel efficient.
http://www.fanwing.com/desc.htm
I thought the rotor forced air on the top of the wing so that the air on top is moving even faster than on the bottom and the pressure difference would be higher. I think that is mechanically induced circulation effect.
The website claims that it is very fuel efficient.
Similar threads
