51
votes
Accepted
Can commercial airliners fly over central Antarctica during winter?
Surface air temperatures aren't really going to be relevant for an airliner. The temperature of the troposphere doesn't vary that much. In fact, the troposphere is warmer at the poles (from Wikipedia ...
- 9,192
43
votes
Accepted
Why was the SR-71 made of titanium?
Because the specific strength of titanium at higher temperatures is better than that of steel (both are much better than that of aluminium).
Specific strength vs. temperature is shown on the above ...
- 63k
33
votes
Can commercial airliners fly over central Antarctica during winter?
They could, if only they were allowed to.
From
§ 121.161 Airplane limitations: Type of route.
(a) Except as provided in paragraph (e) of this section, unless
approved by the Administrator ...
- 63k
32
votes
Accepted
Would building a large asphalt square or painted dark black area create a "thermal generator" for glider use?
Yes, if it was large enough you could expect decent thermals from it, but not all the time. I've flown over mall parking lots where there is maybe 20 acres of asphalt, expecting a boomer, but no joy. ...
- 136k
23
votes
Accepted
If you depressurize an aircraft at FL340, will the temperature inside fall to match the temperature outside?
This depends entirely on how you depressurized it.
Depressurizing the aircraft by fully opening the outflow valve will lower the temperature somewhat, but will not bring it to that outside.
The ...
- 30.5k
22
votes
Does Nitrogen inside commercial airliner wheels prevent blowouts on touchdown?
Apart from the paragraph you quoted, here are a few more reasons.
Dry nitrogen is specified for aircraft use. I believe the rules say that any gas used cannot exceed 5% oxygen content. Because its ...
- 4,576
21
votes
Why was the SR-71 made of titanium?
There is a great article here that breaks it down in depth but its combination of factors made it the best choice, not a single factor (i.e. heat resistance).
But, in reality, the strongest titanium ...
- 102k
17
votes
How hot do internal parts of jet engine get?
This parameter is called Turbine Inlet Temperature (TIT)
Turbine Inlet Temperature (TIT) is the temperature of the combustion
chamber exhaust gases as they enter the turbine unit. The gas
...
- 3,078
15
votes
Accepted
Flex temperature isn't actually "fooling" the FADEC, right?
There are at least two misconceptions in your question:
The way I understand flex temperature is: It's a user interface for pilots to request a derating of engine power to reduce wear on the engine.
...
- 58.3k
12
votes
Does Nitrogen inside commercial airliner wheels prevent blowouts on touchdown?
There is some truth in the claim about inerting. Mostly, blowouts are as a result of high temperatures weakening the rim and tyre and increasing gas pressure within it, rather than being the result ...
- 12k
12
votes
Would building a large asphalt square or painted dark black area create a "thermal generator" for glider use?
I made a short LES simulation
The color is thhe potential temperature and the scale span is 1.8 K between blue and red. There is a hot patch 100 m x 100 m in the middle. There is 0.1 K.m/s (~110 W/m^...
- 1,089
11
votes
Does Nitrogen inside commercial airliner wheels prevent blowouts on touchdown?
In addition to what the current answers mention, it should be noted that the danger is not merely theoretical, though blowouts on touchdown aren't necessarily the primary concern.
Mexicana flight 940 ...
- 19.6k
10
votes
Accepted
What is the temperature of the air leaving the combustion chamber of a CFM56-5C?
Quick answer: At the design point considered, which is assumed to be takeoff conditions, a CFM56-5C combustor raises gas temperature to 1360°C (the share of the compressor in this raise is about 600 °...
- 82.5k
9
votes
Accepted
What temperature is the vapor that forms around a maneuvering aircraft?
I think I've linked to this resource in one of your previous questions.
NASA SP 514
On page 5 (pdf page 15), he derives an expression for the relative humidity around an aircraft.
$$ RH_l=RH_\infty\, \...
- 17.1k
8
votes
Accepted
Why Apollo 11 was launched in summer? (Performance question)
The temperature of the environment doesn't have a significant impact on the performance of a rocket engine. Air breathing engines have better performance in cold air because the mass density is higher ...
- 439
8
votes
How does latitude affect the air temperature at 8 km altitude where planes fly?
In the troposphere, air at altitude is colder than air at ground level. But surprisingly, air at altitude at the poles can be warmer than air at altitude at the equator. From the wiki article on ...
- 63k
8
votes
The phase having the hightest TIT for a flight mission
The highest ITT/TIT/EGT is always seen as brief transient during start, during initial takeoff thrust setting, or during slam accelerations (go-arounds). On the General Electric CF-34-3B1 (the engine ...
- 136k
7
votes
If you depressurize an aircraft at FL340, will the temperature inside fall to match the temperature outside?
Assuming the cabin is pressurized to a pressure equivalent of that at 8000ft, the initial pressure is on board is $P_1$ = 75262.4 Pa, and the temperature is T1 = 20ºC = 293.15K
At FL340, the outside ...
- 84.6k
7
votes
What can cause the engine temperature to be high in piston engines?
Low oil quantity, improper cooling, running excessively lean of peak. Excessive boost from a turbo or supercharger at high altitudes where sufficient cooling is not possible. Ther are quite a few ...
- 75.1k
7
votes
Accepted
How much aerodynamic heating do jetliners endure?
Based on the formula already shown in this answer, we can calculate the TAT (total air temperature), which is the temperature reached at the stagnation point1, from the SAT (static air temperature) ...
- 58.3k
7
votes
Would building a large asphalt square or painted dark black area create a "thermal generator" for glider use?
Yes. Sunlight is about 1000 W/m2. Absorbing it is a good way to get some heat.
We can improve on your design a bit. A good portion of sunlight is visible to the eye, but some of it is not. Not all ...
- 3,481
7
votes
Accepted
Why are the brake temperatures so high during the cruise?
The brakes will be above ambient temperature of the departure airport due to the braking action during taxing.
While airborn there is little airflow to cool down the brakes, so this temperature will ...
- 2,836
7
votes
Why was the SR-71 made of titanium?
NASA was the final operator of the Blackbird and this NASA report contains several valuable information about the SR-71. Just download and read it, it has no equation in it and it's written in a ...
- 16k
6
votes
Accepted
What is the operating temperature of a turbofan engine, and how is it kept at that temperature?
Q1: Assuming that by operating temperature you mean turbine inlet temperature, this article says the Pratt & Whitney F135 engine in the F-35 (JSF) has a TIT of 3600 °F (1982 °C / 2255 K), but that ...
- 4,543
6
votes
What is the operating temperature of a turbofan engine, and how is it kept at that temperature?
Yes, if you could increase the combustion temperature in the hot section of a gas turbine, you could dramatically increase the efficiency of the engine. The problem of course is finding materials ...
- 75.1k
6
votes
Can an S-duct fit a turbofan exhaust instead of the intake?
Yes they can, and it has been done in the Garrett AiResearch ATF3. Although the engine was not hugely successful, it is still being used in aircraft today.
From this answer:
The hot exhaust stream ...
- 63k
6
votes
Accepted
Cessna 182Q (parachute operation) - climb leaning with CHT
Don't bother will all that. Without a proper 6 channel Exhaust Gas Temperature gauge, and fuel injection, you can't hope to do any of that sort of anal-retentive leaning to the nth degree kind of ...
- 136k
5
votes
Accepted
Why is extreme cold weather a challenge at airports, since jets operate at extreme cold conditions in flight?
The extreme cold is not an issue so much as the weather that typically accompanies it and the fact that planes are not always designed to be started in extreme cold with out some assistance even if ...
- 102k
Only top scored, non community-wiki answers of a minimum length are eligible