"Two-thirds of F-22 Raptor fleet suffering from corrosion"

Eh... Typically the Russians had better aircraft, overall. They were better designed and were of better quality because of nationalism and the lack of competition (turned out to be a good thing when it came to "let's build a good one for Mother Russia"). Lowest Bidder mentality has exacted a toll on our military, today.

The biggest problems Russia has with maintaining its aircraft are related to the absolute lack of material to do maintenance with due to lack of money.

Although, yes, they do have issues with their aircraft - it's simply that their engineers were quick to take note of problems they had with aircraft and design future aircraft with those in mind. Because of the communist economy - price wasn't really a concern - quality was.

Although we had an overall better military than Russia did - a number of their ground forces (aside from the AK-47) had issues, as well as their naval forces.

reply to post by Aim64C


Aim64C, first of all let me say how sad I was when the best bird we had was retired. I loved the Tomcat in spite of its maintenance requirements, and instead of dumping money into new wonder projects, a next generation of the Tomcats should have been the priority.

You are dean on with the inherent problems of composites being used so extensively.

F-177s clearly showed that when their wings were suffering catastrophic failures under level flight.

Stealth does give an edge from long range, but when it gets to business of warfare, you always have to get up-close and personal to get the job done, and stealth is not an option there.

While - yes, this can be 'remedied' through maintenance procedures - the fact remains that it's a rather dangerous design flaw that will end up costing even MORE money for an already golden bird.

Exactly. I’m just not sure if it’s a design or a concept flaw.

I never stopped thinking why Russians put stealth concept on the back burner when they were the ones that created the RCS calculation algorithms that Skunk Works boys based their entire project on.

it is also worth its weight in gold.

I’ll actually do to math on that one.

Please tell us when exactly F-117s were falling out of the sky from wing failures in straight and level flight. If you mean the ONE that crashed at an airshow that was determined to be caused by human error at the depot it had just come out of. They failed to inspect the wing bracket and it failed in the display. They failed to install 4 fasteners in the "Brooklyn Bridge" assembly that held the left wing on.

Originally posted by iskander
You are dean on with the inherent problems of composites being used so extensively.

Composites only account for 24 percent of the materials used on the F-22A Raptor, metal alloys account or 61 percent and the rest, as indicated by the graphic, is a radio permeable material used exclusively for the construction of radar dome.



High Definition Version

Originally posted by iskander
Stealth does give an edge from long range, but when it gets to business of warfare, you always have to get up-close and personal to get the job done, and stealth is not an option there.

Right, I take it this is another one of your general grand personal narratives, your opinion has been duly noted, now lets get back to reality.

Originally posted by iskander
I never stopped thinking why Russians put stealth concept on the back burner when they were the ones that created the RCS calculation algorithms that Skunk Works boys based their entire project on.

The "Russians" never really developed a 'stealth' program like the US did with the same level of investment, research and development mainly because they never grasped the concept as early as the US did not with the same level of interests. Also, US researches realized that a formula initially developed by a Russian civilian scientist could be used to model programs which would accurately measure the given radar cross section of a design. US stealth efforts were well underway at that point and were not dependant upon this discovery. So lets not try to suggest by generalization more than what actually happened, you know, history.

But nah, the mighty "Russians" were the first to be acutely aware of 'stealth' and of every facet of it design and how it applied to warfare. Therefore they were able to bypass the research, development and trials phases altogether due to simply omniscient knowledge. Despite all operational history, facts conclusions and trends pointing otherwise the 'stealth' concept is a failure and not useful simply because the "Russians" choose not to develop it, and they must have chose not to develop it due to uselessness. For any other reason used to attribute their lack of progress in the field is simply preposterous given that these are after all the "Russians" we are talking about here.

Originally posted by iskander
I’ll actually do to math on that one.

I'd blush if I were you, if you have to even think about doing the math...

Originally posted by Aim64C
And, why, pray tell, would you make the access panels out of metal when the rest of the plane immediately around it is made out of composites?

You do not know which of the seventeen access panels have been effected, and as the graphic illustrations below show the composition of the aircraft varies widely from area to area; note also the number of access panels. Furthermore maybe in an ideal fantasy world with no real life factors and or applications to consider you can design an aircraft which is corrosive free and made entirely of composites. However I'm sure the developers who spent decades and billions researching the design must have, perhaps, realized reality. That, without even considering secondary factors, in order for the aircraft to achieve a certain level of performance, capability and structural integrity throughout its flight envelope the current metals found on the Raptors would have to be used.



High Defenition Version



High Defenition Version

Originally posted by Aim64C
That should be sealed off rather well.

Let's see, the inherent (see necessary) materials used in the radar absorbing filler itself is the key behind the corrosion when applied to insulate the gaps between the access panels. Now we should insulate the filler with another filler from the access panel edges. [sarcasm]I think we just found a solution for those idiot engineers[/sarcasm].

Originally posted by Aim64C
Titanium is rather corrosion resistant - but they should just make a dang composite access panel.

See above post(s) for clarification on the composite and titanium issue(s).

reply to post by Zaphod58

Please tell us when exactly F-117s were falling out of the sky from wing failures in straight and level flight.

There’s a test flight video shot by a chase plane, showing the wingtip leading edge of the left wing snap and “unravel” exactly like composites do.

Feel free to find it your self. Try NASA archives, they might have it.

Fracture physics, while metals are more linear, composite designs are a lot more complex in managing structure loads, because unlike with metals, a composite point failure will cause a chain reaction failure, kind of like a sweater unraveling when the string is pulled.

www.sri.com...

So wow, that's TWO F-117s that had wing problems, one of which was caused by a QA failure, and one early enough that they were using a chase plane. That's certainly a trend showing for composite materials!

[edit on 11/5/2007 by Zaphod58]

reply to post by Zaphod58

So wow, that's TWO F-117s that had wing problems, one of which was caused by a QA failure, and one early enough that they were using a chase plane. That's certainly a trend showing for composite materials!

It is a trend, and it is statistically systematic.

Here’s an example;

The bad news: Fixing the structural flaws on the F-22A Raptor could cost more than $1 billion, in a worst-case scenario.

The good news is the Air Force won�t have to pay the whole bill.

www.airforcetimes.com...

The Air Force has discovered in its most expensive fighter jet structural flaws that could cost roughly $1 billion to test for and fix, according to service officials.

F-22A Raptor program officials have found weaknesses in structures that attach the wing and tail to the plane�s fuselage, the officials said. A portion of that $1 billion will be used to address aircraft panel corrosion issues.

www.airforcetimes.com...

When ground temperatures are above 120 degrees, the stealthy jet�s avionics begin to shut down after 44 minutes, Air Force officials said. That meets the service�s requirements, but can be too short a time to prep the aircraft for its mission, especially if any last-minute repairs are needed.

www.airforcetimes.com...

October 2007 article states that each panel replacement will cost $50K, that’s PER plate on every Raptor.

Further more, corrosion of the top 4 panels leads to chain reaction galvanic corrosion through out the entire airframe.

We live in an era when a couple of aircraft types seem to have gone on for ever and ever, the DC-3 / Dakota and the B-52 (no doubt due to massive over-engineering and intensive maintenance).

We have apparently forgotten that the forces of nature that degrade the strength of materials, such as metal fatigue and corrosion are just that - forces of nature! Yes, to a LIMITED extent, these problems can be overcome (read delayed), but it is inevitable that in the end these forces will prevail.

In the case of the F-15, the US public (and no doubt the decision makers) have been convinced that the airframes can last longer than the period (cycles) for which they were designed - but on what basis? Do current engineers think that the engineers of 30 or 40 years ago were idiots? In contrast to aircraft such as the DC-3, even aircraft designed 40 years ago, were designed to be no stronger (hence heavier) than they needed to be to endure for their planned life cycle. Do current engineers believe that they can alter the laws of nature? Perhaps they do, but if so they are deluding themselves - and the public.

Nothing, repeat NOTHING lasts forever, especially items made from metal, and short of replacing the metal structure of an object, nothing is going to make it last forever!

Of course this situation is not confined to aircraft, evidence the recent bridge collapses (metal fatigue), steam pipe failure/explosion in New York, etc.

The laws of nature require that every metal bridge will have to be replaced after 'x' number of cycles - there is absolutely no other alternative - you cannot make a metal bridge last forever - it is like talking of perpetual motion, while friction exists perpetual motion is IMPOSSIBLE!

This attitude even seems to extend to the automobile. Yes, advances in lubrication have allowed the extension of time between oil changes (TBO in aviation terms), but they have not eliminated them - and they never will. Unfortunately, the importance attached to vehicle servicing by our grandfathers has now been totally lost on this generation. We no longer service to prevent failure - we just throw the item away when its (shorter than it should be - due to lack of servicing) life is over.

If society can afford such waste then, fine, but let's not deceive ourselves into thinking we can make the same item last forever, just because it will last some finite time without servicing, or component replacement.

So it is well to remember that if we build, say, a bridge then we are not only committing to the cost of the bridge and its maintenance, but eventually it's total replacement after a given amount of usage. In the case of underground structures (such as New York's steam pipes) we had better plan, during its design, for the ability to replace parts or all of the structure. Unfortunately (and no doubt catastrophically) designers (and legislators) only plan for the life of the product not for what has to be done to eventually and inevitably replace the item.

Surely, much of the blame for this falls upon the shoulders of politicians (with the tacit approval of the electorate) who will not make the hard decisions to replace systems BEFORE they planned life has expired, but rather to extend the life of the systems (on obviously shaky and optimistic grounds) merely to get re-elected.

An obvious lesson (which I believe will go unheeded) is the case of the F-15 (and the Nimrod), is that you cannot plan the life of a system such as a warplane - and thus its replacement - on a peacetime utilisation rate, especially when the lead time to introduction of a replacement system is in the order or 20 years or more. If the F-15 structure cannot be repaired, just how many years will it be before the USAF is back to its capability level before the wings started falling off? Perhaps never!

And this from the 'most powerful' nation on earth. How pitifully weak we humans really are!

The Winged Wombat