107 views

### Do airliners use more fuel at low altitude than high altitude? [duplicate]

Air density at lower altitudes is higher, and thus provides more resistance to objects moving through it. Is this higher density enough to practically impact the fuel efficiency of an aircraft flying ...
118 views

### How turbofan engine efficiency increases over altitude or speed? [duplicate]

I am confused a lot about the efficiency and thrust relation with altitude and velocity of an aircraft. If thrust is related to air mass flow and velocity diffrence of bypassed air - exhaust gases ...
72 views

### How do turbofan engines work efficiently at cruising altitude, when the air is thinner? [duplicate]

At FL350, for example, the air is considerably thinner than at ground level. How do jet engines efficiently provide thrust when considering fuel consumption for a certain throttle setting?
40 views

### Turbine engine combustion efficiency [duplicate]

What I read about combustion efficiency of jet engine is ratio of (Th-Tc)/ Th where Th combustion chamber temp and TC exhaust temp. I also read this efficiency reduces with increase in altitude and ...
8k views

### Why are many jet aircraft designed to cruise around FL350-370?

If the flight distance permits, the B737-800 will cruise at FL350, the A320 a little bit higher... Flying at FL370. Photo: Live from the Flight Deck by GolfCharlie232 (reframed) Elements such as: ...
8k views

### Why then don't aircraft fly even higher, for even greater efficiency? [duplicate]

After reading various superb QA on here I now see that (basically) aircraft are more efficient per passenger-mile, at higher altitudes. Why don't we go even higher, than current typical airliner ...
7k views

### Why are jet aircraft never designed with a slower cruise speed?

All jet airliners have a cruise speed between Mach 0.82 and Mach 0.85. At those speeds the aircraft are flying at their maximum subsonic speed. Any greater cruise speed would only be ...
8k views

### Is there any equation to bind velocity, thrust and power?

I am designing a remote controlled airship. I will tune it so that the lift given by Archimedes' Principle will exactly balance the weight of all the structure. It will be propelled by brushless ...
14k views

According to this video on jet engine blades, titanium is never used for the turbine, because it "melts and burns at the temperature of the flame". Only the blades of the compressor are made of this ...
2k views

### What is the relationship between power and fuel efficiency?

We were having a discussion in our ground school that power will make the plane ascend or descend and that you use the stick for speed, forward for higher speed and back for slower speed. So does that ...
6k views

### How far can a 777 fly with just one engine at altitude?

If a 777 pilot wanted to fly further than with both engines running, how many more miles could the plane go with just one engine running, at high altitude?
13k views

### Why has the maximum service ceiling of Boeing and Airbus products remained about the same for 30 years? [duplicate]

When Boeing introduced the 747-100 in 1969, its maximum ceiling was 45,100 feet; half a century later, when Boeing introduced the 777x, its maximum ceiling was 43,100 feet. Similarly, the maximum ...
8k views

### Why does fuel consumption decrease with increasing aircraft altitude?

I have a chart where the thrust ($F$) and the thrust-specific fuel consumption (TSFC) are plotted against the aircraft flying speed, for several altitudes (i.e. sea level, 3000 meters and 11000 meters)...