Forum: Technology

So if you did not take away all of the metal and put a coat of RCC on top of that then you would save weight and it would prevent it from breaking. Or if it were strategically place like only in the leading edges than it shouldn't break either. If the new 787 is made mostly of composite material then how come they use it if it would break easily? The Eagles nose is made of carbon fiber a lightweight composite material and that can handle the stress of military flight, so why not just put carbon fiber on the hot spots of the Eagle.

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Plus there are thousands of aluminum alloys and there is one that is lightweight, heat resistant, and durable for flight but it does not need to be an aerospace aluminum there is probably another alloy that is used for something else that would be compatible for the job of the speed run. With the speed run only being three minutes it would also allow for a safety margin. Three minutes is not that long so the Eagle could go 1875 mph for three minutes without any modifications other than a canopy with high temp glass so that it does not melt.

You don't seem to understand the chemical limits of aluminum. There is no magic formula. Aluminum by nature is brittle and prone to fatigue.

On the contrary, aluminum and its alloys can be made to almost any capacity depending on heat treatments:
http://www.engineersedge.com/aluminum_tempers.htm
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fiskerwad wrote:

On the contrary, aluminum and its alloys can be made to almost any capacity depending on heat treatments:
http://www.engineersedge.com/aluminum_tempers.htm
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I think you overlooked something important in aircraft design. Nobody is going to waste their time with aluminum in aircraft design outside of 2024 because of its strength relative to its weight. Aluminum alloys quickly lose their advantage for weight savings outside this composition. They can overcome fatique to an extent by doping aluminum with copper, but that makes it heavy. By the time you whip up the concoction you're dreaming of the weight of steel and its cost looks much more appealing.

But wouldn't it be possible to alloy aluminum with one of the helium isotopes? That would make it stronger and lighter?
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There is a titanium alloy that is made of mostly aluminum that would save weight and should only add a couple hundred pounds of weight, but two minutes is definitely reasonable it is not long and the Eagle should have enough fuel to give it plenty of tie to go 1875 mph for two minutes without any modifications. Two minutes should not hurt the metal since it is only 120 seconds at top speed.

Perhaps if the heat treatment was done correctly, the heat that was created at 1875 mph would finish the hardening process? The SR-71 was said to anneal itself when it flew, maybe that would work?
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SR-71 also had to go Mach 2 to stop leaking fuel. The Blackbird was purpose built to sustain Mach 3+ at over 80,000 feet for an hour. It did nothing else. Stop trying to turn a highly effective and versitile platform like the Eagle into something it is not.

Yeah but it is only two minutes and what about all the possibilities for the thousands of alloys out there there has to be one out of those that has the strength and weight to allow for the eagle to do that.

The canopy is the limiting factor, I believe. Why not make the canopy from an alloy and install EOTS/DAS from the F-35?
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Why not build the canopy out of the same material the SR-71 used? I would think advancements would now permit such a thing, but then again i'm only guessing!

Oh look, i'm at 500 posts! Shocked

The SR-71 also had steeply sloped screens not a bubble canopy. And the glass got to several hundred degrees and the crew had to wear space suits.

OR, we could build one of those droopy, movable noses like the SST had? Didn't the XB-70 have something like that too? And it was built of stainless steel. Add some compression lift and boron fuel and we could EASILY do 1875 mph for 2 minutes.
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sprstdlyscottsmn wrote:

The SR-71 also had steeply sloped screens not a bubble canopy. And the glass got to several hundred degrees and the crew had to wear space suits.

Fair point about the heat of the glass, though don't many aircrafts canopies heat up to the point that if you touch them you'll get burnt (as in the pilot flying them touching the canopy). I'd have thought that perhaps with modern manufacturing methods the same glass the SR-71 used for its windows could maybe, just maybe be formed into a canopy shape. I have no experience whatsoever with aircraft canopies so do please excuse me if that idea is icomplete nonsense from a professionals viewpoint.

I don't think the space suits are relevent to the glass issue though as the suits were worn because of the altitude the SR-71 flew at and not because of the temp the glass got to, or at least thats what I thought anyway but I could be wrong. Question

Forum: Technology

Composites and Alloys