Why do planes have a maximum flying height?

Question

I just saw that the cessna 172 has a maximum height of 13500 ft. What happens if you try to go higher?

Answer 1

You will suffer from hypoxia / possible engine faliure.

Answer 2

The air gets thinner, so engines will use more fuel, meaning fuel will run out quicky.

Also cessna's are light aircraft, the word 'light' means what it quite literaly says, so to keep the weight down they use thinner 'walls' (so to speak) - that means at higher altitude it will be easily for oxygen to seep out, therefore the pilot will sufficate.

Answer 3

The airs too thin, so the wings can't generate enough lift above that height causing it to stall.

Answer 4

The airframe would suffer from structural problems as the pressure would be too much for it to handle.

Also in some cases if you go any higher there isnt enough oxygen.

Answer 5

In an unpressurised cabin you would not have enough oxygen

Answer 6

As the airplane climbs, the air becomes thinner,reducing the amount of power the engine can deliver. Lower power reduces the ability of the plane to climb,and at 13,500 ft the climb rate would be down to 100 ft per minute.  Some models of light planes use turbochargers to compress the air going into the engine, allowing them to climb higher.   For example a turbocharged Cessna 182 has a ceiling of 20,000 ft.   There are other turbocharged small planes that can cruise as high as 25,000 feet.

   When you go above 12,500 ft in a unpressurized plane for more than a few minutes the pilot is required to use an oxygen system, and oxygen is required anytime you fly above 14,000.

      The thinner air does not reduce the amount of lift from the wings, because the thinner air allows the plane to fly faster.  Airplanes measure their speed through the air by measuring the air pressure hitting the front of the plane, and air pressure is all the plane cares about.  If a plane has the same power available  at  25000 feet as at 5000 feet, the airspeed reading will be the same, as will the air pressure against the  wings, but the plane will be flying over the ground faster.

      The altitude does not produce any extra stress on a unpressurized airplane.

Answer 7

The engines stall because they need air to cumbust and there is not enough at that alt. Next you would get light headed pass out and crash. The propellers don't have enough air to propell you foward. And finally the FAA does not want cessnas orbiting around the earth.

Answer 8

It wont. Some thing to do with thinner air and power output from the engine.

Same as car, on a test bed it could do 200 mph on the road wind resistance prevents it.

Answer 9

the cabin may depressurise

Answer 10

there isn't enough "air" to support combustion, causing the airplane to stall.

Answer 11

That is a nominal ceiling.  That applies to the C172 at maximum allowed weight and in a standard atmosphere.  Fly it considerably lighter on a cold day and it will fly many thousands of feet higher.

Answer 12

The Aircraft will have to be pressurised above that height. Large Aircraft carrying passengers, Boeing 747, Airbus A340 etc, have a pressurised cabin. They fly at Approx 36,000 feet. The pressure at that altitude is is much lower than sea level. At sea level we are subject to 14.7 PSI, this is what an aircraft needs to maintain at 36,000 feet.

This is why in the movies, Aircraft explode so violently, because of the high pressure inside in the aircraft (14.7PSI) equalizing with the low atmospheric pressure, just like a baloon popping, pressure always goes from high to low.

But most Aircrafts maximum heights are calculated to maximise efficiency.

Answer 13

Several reasons: The airframe can't support itself in such rarified air; the engines cannot get enough oxygen to provide reliable combustion and, at that height, oxygen or pressurisation is needed to support the humans that fly the aeroplane.

Answer 14

It becomes a spacecraft.

Answer 15

The service ceiling on the Cessna 172 may be somewhat higher depending on the model, up to as much as 17,000 feet, but the reason remains the same.  First, the service ceiling is not the absolute ceiling, but the (density) altitude at which climb rate is reduced to 100 FPM.  This is because air density is reduced to a point at which the engine is no longer producing sufficient power (climb capability being a function of excess thrust)and the wings no longer producing enough lift to climb at a higher rate.  At the absolute ceiling, the aircraft must be operated at best rate of climb speed simply to maintain altitude.  The physiological needs of the pilots with regards to oxygen have virtually nothing to do with it, as a simple nasal cannula will supply sufficient oxygen at these relatively low altitudes.

Answer 16

you go into orbit

Answer 17

Service ceiling height is the maximum altitude that aircraft can operate with acceptable performance in the rate of climb, thrust and airspeed.

The absolute ceiling height is the maximum altitude at which an aircraft can maintain sufficient height, airspeed and required thrust.

The lockeed U2 spy plane has the highest service ceiling of 85,000ft.

The main factor that restricts any aircraft from reaching an altitude in excess of it's absolute ceiling height is air density, and it is this that effects performance.

As an aircraft climb the air becomes thinner and the airspeed indicated in the AIS reduces.

This effects the rate at which an aircraft can climb and the amount of airspeed needed for sufficient lift.

Allthough some people might relate airspeed to actual speed, the airspeed is measured differently to the speed over the ground.

Becuase the air is thinner at higher altitudes the air required for engine combustion is also effected. To achieve the required air compression a higher speed through the air has to be achieved.

Since the engine performance is reduced the already effected airspeed and climb rate is further reduced making an acceptable rate of climb impossible.

Cessna's and other piston prop aircraft have a mixture control which alters the ratio between fuel and air mixture, this is a requirement on these aircraft since engine performance alters at different altitudes.

To understand what limit's an aircraft in climbing any higher you have to look at aircraft that have reached the limit in what aircraft can achieve.

The U2 reconnaissance plane achieves 85,000 ft by flying close to it's stall speed and near to it's maximum operating speed, known as the coffin corner.This means it can easily stall if it lost 10 knots or overspeed and break up if it gained 6 knots.

The glider like characteristics of the wing means that the U2 has a stall speed of under 50 knots, and when flying at 85,000 ft can ahieve level flight of 50 knots but a ground speed of 500 knots.

If it was to fly higher it would stall and then break up due to stall speed being equal to the critical mach number.

Although passenger jet's and cessna's would never be in this situation it is stall speed that would be reached first.

Answer 18

the engine will cut out unless you have a turbo

the carb will almost certainly freeze also, starving the fuel supply

Answer 19

you'll fly into outer space and get lost

Answer 20

The air at high altitudes is not dense enough for the airplane wings to generate enough lift to hold the plane in the air. A good example is throwing a paper airplane into the wind, if you throw it straight is will pitch up.

Answer 21

It is down to pressure and temperature, temp up there is around -50 degrees, and this is very thin air.

The pressures are immense and 32,000 feet is the best cruising height for a Boeing 747 757 type vehicle, due to the thin air causeing less friction (drag) on the aircraft. Although there is enough drag to lengthen the entire plane by some inches, it is designed to stretch and flex too. We Criise at this height for better fuel economy. Being told to cruise at a different altitude affects the fuel amount used and the airline's profit margins. So they ask for 32,000 feet.

So cruising height is usually determmined as a result of laws of physics rather than a ceiling height. The physics reates to the strength of the machine, the size and shape of windows and the pressures it is designed to withstand!

What is the height limit for the Space Shuttle?

A Cesna is like a roller skate in a Porsche 928 world.

Answer 22

As aircraft climb to higher altitudes, the air outside the craft gets thinner. Airplanes are pressurized at high altitude to afford passengers and operators comfort. The ideal situation would be for the aircraft to be pressurized and maintained at ground level pressure, this is asking too much of engineering of the fuselage would require it be incredibly strong, and subsequently too heavy and expensive, fuel economy wise to fly, in order to withstand the forces imposed on the outside of the aircraft by the pressure maintained inside. Most of the various specifications of jet airliners remains classified.

A typical commercial aircraft cruises at about 28,000 to 35,000 feet. This represents up to  6.5 miles of altitude.

Military aircraft are often able to fly considerably higher than commercial aircraft. In the case of these aircraft, the plane itself is not pressurized but instead the pilot wears a pressurized suit that keeps him contained in a pressurized environment.  U 2 spy planes soar to  altitudes of up to 90,000 feet. The Stealth Bomber cruises at around 50,000 feet, or about 8.5 miles, and so do many other combat aircraft.



The answer to your question is, the maximum altitude of a particular aircraft is determined by the strength of its exterior, weighed against the comfort of the passengers, at the required pressurization to maintain comfort at a certain altitude. Aircraft must be limited in their design by their body weight criteria, and subsequently are  compromised in their limited ability to withstand the forces imposed upon the airframe at higher altitudes.

Does that make sense?

This is not even taking into consideration the fuel intake characteristics and injection/carburation of the engines used in applications at high altitude. That is an issue best left for aeronautical design engineers with an extensive mathematical background and training. Probably someone Chinese, thanks to Bush and his minions.

Answer 23

Max height is based on lift , airspeed and air density . Some answers you have been given say the engines would go out - truth is they do go out on all engines and only a small % of gas is burnt , the engines work more as fans blowing the plane along at very serious altitudes . It is fuel vapour you see in the sky as trails . Altitude limit is set when plane becomes unstable . These limits are discovered in wind tunnels long before the planes of a type ever lift off .

If a plane goes above its limit it goes into a condition known as dutch roll where the plane cannot keep a straight heading so one wing lifts then plane turns other wing lifts and the plane continues like this until it either stalls or breaks up .

Answer 24

There wouldn't be enough air to generate lift and oxygen for engines