Why doesn't a Jet Engine melt??, page 1

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Topic started on 20-5-2009 @ 05:14 PM by muzzleflash

It occurred to me that if the WTC was brought down by burning jet fuel fires, than why is it that jet engines do not melt?

i was very curious because jet engines seem to operate safely and the metal that they are made of does not melt or warp to any extreme degree (that i know of)

so how can jet fuel burn inside a jet engine without melting the metal of the plane?

i mean obviously it burns pretty hot right?

what is a jet engine made out of?

sorry for my naive thread/questions/curiosity

reply posted on 20-5-2009 @ 05:23 PM by GenRadek

Usually jet engines have titanium parts that can withstand such temp extremes. Hence why they dont melt. Steel would not be able to survive such high temps for a long period of time.

reply posted on 20-5-2009 @ 05:25 PM by muzzleflash

Originally posted by GenRadek
Usually jet engines have titanium parts that can withstand such temp extremes. Hence why they dont melt. Steel would not be able to survive such high temps for a long period of time.

so they use titanium? even the first jet engines?

i assume rocket engines are made from this material as well or no?

problem is, i cant find any info that actually details the materials used in construction, but rather almost all wiki's describe simply the construction and mechanics

reply posted on 20-5-2009 @ 05:45 PM by eniac

for some components, jet engines have to use materials with a very high resistance to heat.

If memory serves me right, the first production jet engine was that of the Nazis' ME-262, and they had a big problem because they couldn't get their hands on such materials (the Allies had them boxed in at this stage). So the 262's engine had to be rebuilt after about 10 hours of use -- parts of the engines just burned to s^^t.

I think titanium is used, and these guys reckon 'nickle based superalloys' are also used (whatever they are).

reply posted on 20-5-2009 @ 05:51 PM by reticledc

They don't melt? Really!?
I guess we need to find a better explanation to why we found a few black boxes but no engines in a particular situation we are all familiar with.
Well then, on with my life....

l8r sk8r

reply posted on 20-5-2009 @ 05:58 PM by CreeWolf

Jet engines are cooled primarily by "bypassed" air. Turbofans are especially efficient in this regard. And, of course, jets have an oil cooling system just like your automobile engine.

reply posted on 20-5-2009 @ 06:00 PM by ZombieJesus

Strong, lightweight, corrosion-resistant, thermally stable components are essential to the viability of any aircraft design, and certain materials have been developed to provide these and other desirable traits. Titanium, first created in sufficiently pure form for commercial use during the 1950s, is utilized in the most critical engine components. While it is very difficult to shape, its extreme hardness renders it strong when subjected to intense heat. To improve its malleability titanium is often alloyed with other metals such as nickel and aluminum. All three metals are prized by the aerospace industry because of their relatively high strength/weight ratio.

www.madehow.com...

This link should answer your question

Cheers

reply posted on 20-5-2009 @ 06:24 PM by Nipples

Engine thermal management schemes incorporate a number of the things listed above. Titanium is used in the less-hot regions of the engine, while nickel-based superalloy's, ceramics and exotic materials that make $1200/oz. platinum look like a steal are used for the hottest sections. As mentioned above, 'cold' air (cold relative to the temperature a given part is exposed to) is used to cool the hot parts, but this decreases engine performance. Therefore, engine thermal management is a never-ending dance of cost/weight/performance/life that hopefully closes to a solution.

For the record, parts do not need to melt to fail. Metals lose tensile strength as the temperature they are exposed to is increased, and thus a part of a given material under a given stress will fail via fracture when exposed to increasing temperature due to the material not being able to support the stress/strain at that elevated temperature. I refuse to open the WTC conspiracy Pandora's Box, but I will reiterate that metal does not need to melt to break - under stress it can (and will) fail at elevated temperatures well below it's melting point.

reply posted on 20-5-2009 @ 07:54 PM by FredT

reply to post by Nipples

Your are quite correct. If turbine sections expand with heat they could comeint contact with other part of the engine destroying it.

The F119-PW-100 that comes on the F-22A Raptor

Integrally bladed rotors: In most stages, disks and blades are made from a single piece of metal for better performance and less air leakage.

Long chord, shroudless fan blades: Wider, stronger fan blades eliminate the need for the shroud, a ring of metal around most jet engine fans. Both the wider blades and shroudless design contribute to engine efficiency.

Low-aspect, high-stage-load compressor blades: Once again, wider blades offer greater strength and efficiency.

Alloy C high-strength burn-resistant titanium compressor stators: Pratt & Whitney's innovative titanium alloy increases stator durability, allowing the engine to run hotter and faster for greater thrust and efficiency.

Alloy C in augmentor and nozzle: The same heat-resistant titanium alloy protects aft components, permitting greater thrust and durability.

Floatwall combustor: Thermally isolated panels of oxidation-resistant high cobalt material make the combustion chamber more durable, which helps reduce scheduled maintenance. www.globalsecurity.org...

reply posted on 20-5-2009 @ 08:04 PM by GenRadek

reply to post by reticledc

uhh they did find the engines of what you are alluding to. banged up of course, but not melted.

reply posted on 20-5-2009 @ 11:29 PM by firepilot

Ughhh, one of the twoofers.

jet turbine engines are engineered for high temps, but even they can be harmed by high temps. They require a certain amount of air moving through to keep the temps below a certain level. Let the interstage turbine temp get too hot, it will damage the engine. When starting a turbine, it has to be spinning a certain amount, before introducing fuel to it, or it can be destroyed.

You cant compare structural steel with turbine grade high temperature metal alloys. I know for 9/11 conspiracy theorists, metal is just metal no matter what it is made of, and a burning building is apparently no different then a jet turbine.

reply posted on 20-5-2009 @ 11:52 PM by anonamousantichrist

It's late so I may be off here. However, I seem to recall most jet craft to be using kerosene as the fuel.

Kerosene becomes combustive in the open air at around 575 degrees F. Most aircraft alloys (recent ones anyway) can withstand that temp. When you combine the low combustion point with a forced air induction, keeping the turbine within "spec" should not be that difficult.

Please keep in mind, There is a strong possibility that I pulled most of the above statement directly from my rear end. As a result, it may be somewhat "off" factually speaking (or totally LMFAO).

AA

reply posted on 21-5-2009 @ 12:09 AM by Aim64C

reply to post by anonamousantichrist

I'd have to check the flash-point of JP-5, again... but most are designed with a very high flash-point (when the fuel ignites) to keep unintentional fires to a minimum.

However, the fuels burn much hotter depending on the circumstances. The flash-point is simply what temperature is required to trigger the necessary chemical changes that result in an exothermic reaction (fire/heat).

In a sense - they are modified forms of kerosene - though most jet engines are not incredibly picky about what they will burn. Many aircraft carry around a kit that can test various fuels and oils to see if they will provide enough power to put the aircraft in the air.

reply posted on 21-5-2009 @ 12:26 AM by Darkpr0

reply to post by muzzleflash

Well, it turns out that jet engines do melt when they operate outside of parameters that they were designed for. The best example of this is probably the MiG-25 Foxbat. A high-altitude, high-speed reconnaissance and interception aircraft, it went fast. Real fast. Top speed was Mach 3.2. But this little section from Wikipedia shows why Mach 3+ was not such a great idea.

Tumansky R-15

At dry thrust the engine could produce 7,500 kilograms force (73.5 kN, 16,500 lbf), and at military power (using afterburners) the output is 11,200 kilograms force (110 kN, 24,700 lbf). This allowed speeds of up to mach 3.2 in the Mikoyan-Gurevich MiG-25 (which used two engines). However, at speeds above mach 3, the force of the engine sucking fuel through the pumps overwhelmed the pumps' ability to limit the flow. At this point, the engines effectively became ramjets, as air began to bypass the low pressure compressors, accelerating out of control until the pilot could regain throttle control through using firewalls or compressor stall, or the tanks ran dry.

The engine literally runs out of control and basically goes into overdrive. It's akin to setting a guitar amp to 11. The result, however, is that the engine becomes useless as the heat and force exerted by such high speeds damages it to the point where it will need a major overhaul to be usable again. It's worth pointing out that this aircraft is not terribly old, so it's not something condemned to the annals of history.

Of course, the Soviets didn't have access to more modern superalloys or ceramics as we do now, but it just goes to show that even more modern engines can more or less melt themselves if they're not run properly.

Pr0

reply posted on 21-5-2009 @ 01:04 AM by anonamousantichrist

reply to post by Aim64C

Understood.
Thank you for the clarification Aim64C. It's a always a nice surprise when someone offers corrective criticism with a touch of class. Usually (as of late anyway and I'm guilty of this as well), the person offering some sort of correction also includes a nice, steaming, beetle infested, syringe of "truth serum" that usually involves demeaning, insulting name calling from that person's high horse. One would think that with the thin air up there, it would be hard to type. If there is a will, there is always a way I guess LMAO.) I know, I tend to get carried away.
It's in my nature......

after all, i am the anti christ and indulgence is my middle name

AA

reply posted on 21-5-2009 @ 11:17 AM by firepilot

you cant compare the temperature of burning kerosene or its flashpoint, to what goes on inside a inside a jet turbine.

There are multiple compressor stages, that greatly squeeze the air too before the combustion chamber, and the engine stages can be spinning at 30,000 rpm too. So the burning in a turbine is greatly under pressure too, which increases the temps. Some turboprop engines do not do all that well above 25000 ft since there is not enough air moving through it to keep things cool.

But yes, turbines can burn lots of different fuels, since it is a totally different dynamic than a piston engine. You can put gasoline in an F-16 and it would fly. You cant put jet fuel in a piston aircraft and expect to do anything

reply posted on 21-5-2009 @ 04:23 PM by punkinworks09

reply to post by firepilot

Theres a really good story about an israeli pilot, 1973 war?, whom found himself out of fuel over syrian territory.
He landed at anbandoned syrian outpost, filled his jet up with gasoline from a truck, and got it lit and flew it home.The story was a "drama in real Life" from readers digest.
Jet engines may run on a lot of things but they dont like gasoline so much, it has to much energy available.

reply posted on 22-5-2009 @ 04:07 PM by kilcoo316

Short answer - they would melt if it weren't for the internal cooling ducts within the blades.

Long answer - it would bore you to death and I'm too lazy to bother!

reply posted on 26-5-2009 @ 02:34 AM by Aim64C

reply to post by anonamousantichrist

You're welcome.

It's interesting to get into a lot of the details (it interests nerds like me) - but often many of these people tend to miss where the misunderstanding is occurring.

It's what happens when people lose faces to place with names and opinions. It somehow, in our minds, diminishes the importance of explaining something to a person while appealing to those among us who are hyper-competitive, intellectually, and like to leave no syllable left of 'the enemy's' statement/opinion.

I go into that mode from time to time, but try to realize that not everyone is here to rip words to shreds, and some are genuinely asking a question.

It also doesn't help when you deal with various 'truthers' from different communities asking loaded questions every time you turn around. That's an issue a bit more confined to ATS forums, however.

But - in essence, the answer to why a jet engine doesn't melt is similar to why a butane torch doesn't melt. It's built to maximize the energy transferred to the air (which is then transferred to some other object) - not to the torch, itself.

A million different factors aside - it's that simple. Melted torches are about as useful as a melted jet engine - so they are designed so that doesn't happen (in a variety of different ways).

reply posted on 26-5-2009 @ 02:45 AM by Kaytagg

reply to post by muzzleflash

Because jet fueled fires did not melt the WTC. Not that I'm saying this indicates conspiracy or whatever on the governments part, it's simply a fact that burning jet fuel will not be hot enough to melt steel.

Occam's razor.

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