52
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 ...
- 9,122
44
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 ...
- 60.8k
34
votes
Accepted
How do fast-flying aircraft avoid overheating?
To avoid overheating, the usual trick is to select the right material:
The Concorde used a special aluminium alloy, called Hiduminium, which had higher strength at elevated temperatures and allowed ...
- 226k
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 ...
- 60.8k
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. ...
- 122k
31
votes
Accepted
What is the typical temperature of an airliner's hull during flight?
There are two primary factors that affect the skin temperature of an aircraft in flight: the air temperature, and the speed of the aircraft.
The air temperature where airliners cruise is relatively ...
- 70.8k
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 ...
- 19.4k
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 ...
- 4,526
20
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 ...
- 99.2k
19
votes
Accepted
How are temperature differences handled in a jet engine?
1. The combustion chamber
Temperature here is usually controlled via design of the chamber shape, in particular of the location where combustion occurs vs the airflow.
Image source
In the image ...
- 32.2k
16
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
...
- 2,550
15
votes
What sort of issues related to extreme heat (115°F, 46°C plus) would prevent takeoffs or landings?
Aircraft performance is a many-faceted topic. Insofar as it being so hot that operation is prohibited, a couple of things come to mind.
Aircraft performance figures are supplied by the aircraft ...
- 39k
14
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.
...
- 52.8k
13
votes
What effect does cold weather have on helicopter performance?
Cold weather definitely affects the performance of helicopters (as it does all aircraft), because it affects the density of the air they move through.
I will ignore icing so let's assume dry air.
...
- 31k
13
votes
How do fast-flying aircraft avoid overheating?
I'd like to answer with a focus on the SR-71, since I happen to have a book that gives details on its design.
Ben Rich was the lead of the propulsion and thermodynamics group for the SR-71, and Kelly ...
- 799
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 ...
- 11.9k
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^...
- 1,010
11
votes
Accepted
Cargo aircraft temperature
Many things including bottles containing liquids break when the temperature drops below zero, so the cargo hold is always maintained above freezing; 7°C is typical (source). This applies to both ...
- 344
11
votes
Accepted
Do jet engine exhausts usually glow orange?
Both images you posted are of Pratt&Whitney J58 afterburning turbojet that was used on the Lockheed A-12 and Lockheed SR-71 aircraft. That engine ran particularly hot.
The engine was designed for ...
- 55.8k
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 ...
- 19.2k
9
votes
What appears on EGT Gauge if the mixture is rich or lean?
The exact number on an EGT gauge is usually meaningless: The Alcor EGT gauge you'll find on many aircraft has no temperature markings on it - just 25-degree divisions, and a yellow "reference pointer" ...
- 68k
9
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 °...
- 68.7k
8
votes
Can heated air be provided in the cabin in commercial airlines?
The fresh air vents near your head at each seat can not be adjusted for temperature individually. Cabin temperature is controlled. Just ask a Flight Attendant to warm it up as they have a control ...
- 36.8k
8
votes
How do fast-flying aircraft avoid overheating?
There are multiple ways to avoid overheating.
The simplest method is to use a high temperature material- like Titanium in SR-71 or steel alloy in Mig-25; in Concorde, a special aluminum alloy (AU2GN) ...
- 99.6k
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 ...
- 429
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 ...
- 60.8k
7
votes
What effect does cold weather have on helicopter performance?
First, I don't think cold weather had anything to do the stopping of rotor. Probably a malfunction.
However, Helicopters do face a number of problems during flight in cold conditions
Ice ...
- 99.6k
Only top scored, non community-wiki answers of a minimum length are eligible