F22 mishap or more that meeets the eye?

I bet one could even get Linux to run on F-22 hardware, lol.

Total oxygen failure at high altitude will black out the pilot within seconds and he'll soon die unless the plane descends out of control into thicker air and he revives in time to regain control.
If it only partially fails, he might have time to dive to a lower breathable altitude before blacking out..
Sometimes partial failure will actually make him feel happy and he'll fly on at high altitude without realising there's a malfunction and will eventually black out.

WIKI- en.wikipedia.org...(medical)

reply to post by RichardPrice

Bus and socket technologies have hugely changed in computers over the past 15 years, with significant speed increases and error handling along the way.

The front-end has changed, considerably, sure. More has changed with the substrates between layers of board than the physical buses that front-end plugs into.

And not in the case of fiber optics - which have largely replaced the old cannon-plug style avionics in data-centric airframes.

A hardware DSP will always, always *always* outperform a distributed architecture for the same power, cooling and space requirements. Always.

Simply, no.

There are two basic computational tasks. Serial and parallel. Every task can be expressed in both a serial and parallel form, but some are more inherently one way or another (such as data compression being largely serial but raster rendering being ridiculously parallel).

The floating-point performance of a cheap, entry-level graphics processor runs circles around top-of-the-line x86-64 processing cores. You can run physical simulations of the hardware-specific design on the graphics card that complete just as fast as the DSP can operate. With comparable power requirements.

Certain specialized components - such as sensors, yes, will likely be custom designed (to interact with common bus interfaces, actually; much like your camera has a USB standard interface).

The only reason we do not use DSPs in everything is because they are essentially single-task orientated, while most super computers are designed to be used for multiple tasks.

You are talking about apples and oranges, here. The applications you are talking about are ancient. Back when you had the amplified radar return physically driving the electron beam on a CRT radar scope. That went bye-bye with the AWG-9 centered on the 8080(or 86) processor.

It's an ancient design philosophy, even. Even in the flight control avionics - (fly-by-wire) - the pilot is never directly in control of the aircraft. That is all run by computer. The computer takes the pilot's input and decides how best to contort the surfaces under the current and projected conditions to get the desired outcome.

Electronics are no longer the monkey in the middle. They are the crew that interprets and applies the orders of the captain.

But a modern aircraft is full of tasks that can be happily processed by single-task chips - there is extremely little general purpose computing involved in a modern aircrafts systems. Even the tasks you highlight can be handled much better by a hardware DSP than a general purpose computing architecture - they are well defined problems with well defined solutions, you put X in and want Y out. You will always put X in and want Y out. Therefor you do not use a general purpose computing architecture, you use specific hardware to do that.

Again, no.

The airframe is subject to thousands of different forces with monitors for them located throughout several hundred different arrays and sensors. There are sensors on the airframe that sense the load on the wing - artificially limiting the aircraft's turning performance to keep it from buckling under the G-forces of maneuvering. That has to be factored in with input from the pitot tubes - as there's an atmospheric anomaly detected at the nose and about to hit the port intake in three milliseconds.

You're not just processing a signal. You're computing in gigabytes of physical environment simulation while monitoring (and contributing to) the combat network, monitoring your own active/passive arrays, and presenting a clean, intuitive interface for the pilot to interact with.

You're talking about the hardware peripherals - the temperature sensors that run thousands of samples per second and process them for a slightly slower standard interface; the pitot tubes feeding the environment simulation, etc. Yes, those are application specific.

However, when we're talking avionics - we're usually talking about the central core the pilot interacts with. 50 years ago, yes, that used to be a CRT driven by Analog (and later, some digital) processors. The hardware was completely passive and required the pilot for everything.

Now, the avionics are interactive. It classifies radar contacts (processing even the smallest of returns), automatically counters jamming attempts, etc. It does more than a whole room full of RIOs could do, and feeds that information to the pilot (and Flight Officer, if present).

It sounds a bit excessive, until you see some of the results. Information processing and distribution is the new thing in warfare. "Black" super-x projects have largely been replaced by combat awareness networks and development of them.

There is an emergency generator being developed that will automatically activate as necessary, however, they won't complete testing until late this year, and will install it into 10-12 aircraft a month.

The current unofficial theory is that there is a combination of the Combat Edge upper body pressure suit, and a condition known as accelleration atelectasis(sp?) that is causing the hypoxia like symptoms in the pilots. The suit prevents the pilots lungs from expanding completely under the pressure of the oxygen system, and the atelectasis causes the sacs in their lungs to collapse. Since Raptor drivers can do two a day sorties, they don't have time to recover from this condition like U-2 pilots, who also suffer from the condition.

The Combat Edge upper pressure-garment worn by US Air Force pilots flying the Lockheed Martin F-22 Raptor might be the cause of the fifth-generation fighter's oxygen maladies, sources say.

While pilots need counter-pressure from the vest-like pressure garment to exhale at low cabin pressures found in the Raptor's cockpit, the Combat Edge and associated breathing systems might be providing too much pressure especially under g-loading.

"It just seems a little weird to breathe of off this thing," one source says. "Because you can't expand your lungs as easily because you have something restricting you."

The extra load imposed on the pilots by the added pressure under g-forces could be causing them to "over-breathe the system".

A compounding factor may be a condition known as acceleration atelectasis. The condition causes the pilot's lungs to have trouble bringing oxygen to the blood system because pure oxygen--93% oxygen in the Raptor's case-- and high gravity loads set up the pilots for a condition where the air sacs in the lungs suffer partial collapse.

www.flightglobal.com...