Forum: Technology

TEG, just reading up this thread and I guess I'm curious to how well strategically placed composites in lieu of aluminum would hold up to sustained mach 2+ heat stress? Thanks...

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Depends on what type of 'composite' your talking of? Some are designed for heat, others are not? The Space Shuttles use a composite on their leading edges too.

I don't know too much about composites, except for the minimal amount of carbon-fiber parts used in the engine nozzles.

Shrug

TEG

That_Engine_Guy wrote:

Depends on what type of 'composite' your talking of? Some are designed for heat, others are not? The Space Shuttles use a composite on their leading edges too.

I don't know too much about composites, except for the minimal amount of carbon-fiber parts used in the engine nozzles.

Shrug

TEG

Thanks for response. I guess I was just reading on Wiki about the boasted use of leading-edge composites forinstance, as claimed per some of the J-11B modifications.

So yeah, for disclosure sake, my bias would support a modified F-15Xx including higher use of properly mixed composites both for heat-durability and weight considerations. If they can get reduced RCS out of higher composite construction, then more power to them.

And if they can someday upgrade power w/ Thrust Vectoring PW-232 plants, then just maybe we can get TEG on board for a speed run? Salute

Aren't composites lighter than aluminum alloys. Wouldn't that also save weight and give the F-15C the ability to go 1875 mph for five minutes without a worry for that safety concern, and then get back to a tanker or base that is close by.

mustang65 wrote:

Aren't composites lighter than aluminum alloys. Wouldn't that also save weight and give the F-15C the ability to go 1875 mph for five minutes without a worry for that safety concern, and then get back to a tanker or base that is close by.

How long do you suppose it takes an F-15 to reach its maximum speed(and the fuel burned to do this)? Now that you're at maximum speed and burning fuel at a high rate, you still need to have enough fuel left so you have a safety margin when tanking and/or landing. If you fly at max speed for 5 minutes, you're not going to have a margin for safety. You still haven't answered the most important question- what is the point of this?

Yeah and with the decreased weight form the composite material the F-15C should be able to get to 1875mph quicker and have less of a worry for high temperatures at such a high speed.

Are composites lighter than aluminum alloys, and aren't they able to with stand more heat then aluminum and titanium alloys?

Most composites suffer problems with hardness and stiffness characteristics. The skin of the leading edge made from composite wears off, especially in the extremes of sand and wind blown dust. Your parts may also end up heavier in comparison the stainless or aircraft grade aluminum due to the lack of stiffness. Composites are not the fixall or endall to engineering.

But I bet there is a composite out there that would have the durability to withstand the heat and stress of high speed flight.

Yes it's called the Space Shuttle, and we all know how heavy they are. LMAO

Give it up Mustang!

Your space shuttle uses carefully tiled ceramic pieces on the leading edge. They are about as inert as material gets yet it still requires it to be pieced together because one monolithic piece would crack and disintegrate in flight.

My point exactly!..

Elite 1K Joined: May 26, 2005 - 08:39 PM Posts: 1496

madrat wrote:

Your space shuttle uses carefully tiled ceramic pieces on the leading edge. They are about as inert as material gets yet it still requires it to be pieced together because one monolithic piece would crack and disintegrate in flight.

Actually the leading edges and nosecone of the Shuttle are made from carbon-fiber reinforced carbon composite material (RCC or C/C for short). It's a lightweight high temperature tolerant but brittle material that would be entirely unsuitable for an all-weather atmospheric aircraft.

You could use something to reinforce it can't you? I mean if it was designed to take the stress of coming back to Earth then it must be able to take a couple of high g turns or a speed run. You could strip some of the metal maybe and put some RCC coat above that so it would save some weight and provide protection against the heat. With less weight the Eagle could get to 1875 mph considerably faster.

The RCC is only a coating for the outside of the shuttle, and is laid down on top of it's conventional aluminum structure.

Forum: Technology

Composites and Alloys