wilheldp_PE
PE, LEED AP, SPAM KING
How come I have never thought of this? How DO planes fly upside down?
Good Question
- Thread starter wilheldp_PE
- Start date
Help Support Professional Engineer & PE Exam Forum:
How come I have never thought of this? How DO planes fly upside down?
snickerd3
Taking suggestions
no clue...i'll leave it up to you experts figure out and then pretend i knew it in later conversations
Sschell
Dude?
the slats change the shape of the wing.
and momentum.
and rainbows with butterflies.
and momentum.
and rainbows with butterflies.
wilheldp_PE
PE, LEED AP, SPAM KING
Unicorn farts?
Sschell
Dude?
^now thats just silly.
Last edited by a moderator:
Capt Worley PE
Run silent, run deep
Where's Flyer when you need him?
Flyer_PE
Jr. PE / Sr. Company Pilot
The aviation term is Angle of Attack. It's basically the difference between the direction the wing is pointed and the direction it is actually moving. A flat board will work as a wing, just not a very efficient one.
Wolverine
Uncanny Pompadour
I was going to guess that when a plane is flying upside down, it actually has to fly down a bit, which is actually up, in order to stay up, which is actually down if you're sitting in the cockpit, but is up if you're standing on the ground.
Either that, or else they use Rainbow Power.
I think Flyer is just making stuff up.
Either that, or else they use Rainbow Power.
I think Flyer is just making stuff up.
Capt Worley PE
Run silent, run deep
Why couldn't Emory make the outside loop in The Great Waldo Pepper?
Flyer_PE
Jr. PE / Sr. Company Pilot
Flyer_PE
Jr. PE / Sr. Company Pilot
When upside down, you push forward on the stick and hope the Rainbow Power holds out until you can get back upright.
There I was at 25 thousand feet with three engines on fire....
DVINNY
2-time 10K winner
I get it.
It's like when I walk on the ceiling. I squat to get my head higher, and I jump to get closer to the floor. Simple enough.
It's like when I walk on the ceiling. I squat to get my head higher, and I jump to get closer to the floor. Simple enough.
Wolverine
Uncanny Pompadour
This thread takes a nose-dive in 3...2...1...
I like to have my co-pilot push forward on the stick, then pull up real fast.
Last edited by a moderator:
Capt Worley PE
Run silent, run deep
I can hold a mirror pointed up at the ceiling. It looks like I'm walking on the ceiling. is that the same principle?
When I first saw that XKCD comic a week or two ago, I had to look it up for myself.
The first thing that occurred to me was that stunt planes fly upside down a lot and I was angry that I never thought about them in terms of the simple airfoil lesson.
Wikipedia saved me:
http://en.wikipedia.org/wiki/Airfoil
http://en.wikipedia.org/wiki/Angle_of_attack
Flyer is right, of course... especially about the rainbow power.
The first thing that occurred to me was that stunt planes fly upside down a lot and I was angry that I never thought about them in terms of the simple airfoil lesson.
Wikipedia saved me:
http://en.wikipedia.org/wiki/Airfoil
http://en.wikipedia.org/wiki/Angle_of_attack
Flyer is right, of course... especially about the rainbow power.
Form follows function.
Most planes can't fly upside down due to the mechanical systems, pumps, etc, won't work properly upside down. Also, most commercial planes are made for fuel efficiency, which means a substantial amount of lift from the wing is designed-in (high ratio of upper camber to lower camber is the primary).
Planes that can fly upside down fall into two categories: those that can loop and do other basic tricks, and those that can fly any direction without any issue. The wing design is a major design element. Military planes have not only the internal systems, but their wing design often has nearly an even ratio of the upper to lower camber. The wings barely provide any lift at all, the engines do - that is one reason that military fighter jets are both loud and fuel-inefficient. Stunt planes also generally have the same characteristics. http://en.wikipedia.org/wiki/File:F-16_JeffCO.jpg As shown here, there's very little camber, and the wings are fairly flat.
Wings that are designed for short term upside down have a similar design to planes that don't - but, they have systems that work properly, and a medium ratio of upper camber to lower camber. Correcting by steering "down" will give effective lift.
Another aspect is stalling. Stalling may mean either a loss of wing lift, or the engine itself has stopped. Nearly all planes will stall (lift) if below a certain airspeed or too high of an angle. A loss of wing lift can be made up for by engine thrust, again a reason that fighters are loud.
It is more costly, although it is possible to design a low stall (an "unstart", where the engine is not working) speed, or even engines that don't stall, even if the plane is moving backward - e.g. when the nose is pointed up, and the plane is falling. Again, engine thrust can overcome a lot. A stunt or fighter plane that loses engine thrust (unstart) will fall, about like a rock, due to not having much wing lift. A commercial plane, like a Cessna, or a 747 has a huge wing lift and can glide fairly well, in emergency situations - http://en.wikipedia.org/wiki/Gimli_Glider.
Engine thrust: for example: An F-15 has a total thrust of about 58,000 lbf, and weighs 81,000 lb (.71 ratio). A 747 has a total thrust of about 190,000-266,000 lbf and weighs 735,000 - 975,000 lb. (.25-.27 ratio). Therefore, the F-15 has three times the engine thrust per pound as a commercial airliner.
Most planes can't fly upside down due to the mechanical systems, pumps, etc, won't work properly upside down. Also, most commercial planes are made for fuel efficiency, which means a substantial amount of lift from the wing is designed-in (high ratio of upper camber to lower camber is the primary).
Planes that can fly upside down fall into two categories: those that can loop and do other basic tricks, and those that can fly any direction without any issue. The wing design is a major design element. Military planes have not only the internal systems, but their wing design often has nearly an even ratio of the upper to lower camber. The wings barely provide any lift at all, the engines do - that is one reason that military fighter jets are both loud and fuel-inefficient. Stunt planes also generally have the same characteristics. http://en.wikipedia.org/wiki/File:F-16_JeffCO.jpg As shown here, there's very little camber, and the wings are fairly flat.
Wings that are designed for short term upside down have a similar design to planes that don't - but, they have systems that work properly, and a medium ratio of upper camber to lower camber. Correcting by steering "down" will give effective lift.
Another aspect is stalling. Stalling may mean either a loss of wing lift, or the engine itself has stopped. Nearly all planes will stall (lift) if below a certain airspeed or too high of an angle. A loss of wing lift can be made up for by engine thrust, again a reason that fighters are loud.
It is more costly, although it is possible to design a low stall (an "unstart", where the engine is not working) speed, or even engines that don't stall, even if the plane is moving backward - e.g. when the nose is pointed up, and the plane is falling. Again, engine thrust can overcome a lot. A stunt or fighter plane that loses engine thrust (unstart) will fall, about like a rock, due to not having much wing lift. A commercial plane, like a Cessna, or a 747 has a huge wing lift and can glide fairly well, in emergency situations - http://en.wikipedia.org/wiki/Gimli_Glider.
Engine thrust: for example: An F-15 has a total thrust of about 58,000 lbf, and weighs 81,000 lb (.71 ratio). A 747 has a total thrust of about 190,000-266,000 lbf and weighs 735,000 - 975,000 lb. (.25-.27 ratio). Therefore, the F-15 has three times the engine thrust per pound as a commercial airliner.
D
Dexman PE
^^ heh, heh. He said thrust per pound...
