F-22 Structural And Ski Corrosion — Military Forum

Sponsor Message:


My Starred Topics \| Profile \| New Topic \| Forum Index \| Help \| Search

F-22 Structural And Ski Corrosion

kanban From United States of America, joined Jan 2008, 2468 posts, RR: 21
Posted (2 years 5 months 1 week 3 days 15 hours ago) and read 5012 times:

Support Airliners.net - become a First Class Member!

the attached article indicates the F-22 has been experiencing corrosion problems at the interfaces between metal and some of the radar absorbing materials...

http://www.bloomberg.com/news/2010-1...million-in-repairs.html?cmpid=yhoo

it goes on to say they are trying to prevent the same problem on the F-35

7 replies: All unread, jump to last

Shmertspionem From India, joined Aug 2006, 451 posts, RR: 1
Reply 1, posted (2 years 5 months 1 week 3 days 14 hours ago) and read 4965 times:

so was this the maintenance problem that required 30+ hrs maintenance per 1 hour flight or is this in addition to that problem?

I see they're fixing everything except the small drainage holes...... so basically no real way out of the problem?

Vi veri universum vivus vici

GST From United Kingdom, joined Jun 2008, 927 posts, RR: 0
Reply 2, posted (2 years 5 months 1 week 3 days 8 hours ago) and read 4865 times:

Corrosion at a join between composite materials (more specifically usually the bonding resin and the metal) and metals is nothing new, usually the metal can be treated with a hard wearing coating material being painted on or dipped in to. I wonder why it hasn't worked here.

Quoting Shmertspionem (Reply 1):
required 30+ hrs maintenance per 1 hour flight

Is that 30 man hours or 30 team hours? The first isn't so bad, the second would be worrying as heck.

Shmertspionem From India, joined Aug 2006, 451 posts, RR: 1
Reply 3, posted (2 years 5 months 1 week 3 days 1 hour ago) and read 4694 times:

Quoting GST (Reply 2):
Is that 30 man hours or 30 team hours?

30 team hours. it involved, removing and replacing parts, new adhesives and panels (don't know if that was the corroded parts - or if this is an altogether new problem)

Vi veri universum vivus vici

flagon From France, joined May 2007, 133 posts, RR: 0
Reply 4, posted (2 years 5 months 1 week 2 days 4 hours ago) and read 4397 times:

Quoting GST (Reply 2):
Corrosion at a join between composite materials (more specifically usually the bonding resin and the metal) and metals is nothing new, usually the metal can be treated with a hard wearing coating material being painted on or dipped in to. I wonder why it hasn't worked here.

I am assuming you are talking about galvanic corrosion between the carbon contained in typical composite materials and aluminum, anyway unless I missed something the report does not mention composite material in any way, it mentions stealth materials, stealth materials are not necessarily composite materials...

Stephane

connies4ever From Canada, joined Feb 2006, 3857 posts, RR: 13
Reply 5, posted (2 years 5 months 1 week 1 day 17 hours ago) and read 4226 times:

Quoting Shmertspionem (Reply 3):
30 team hours. it involved, removing and replacing parts, new adhesives and panels (don't know if that was the corroded parts - or if this is an altogether new problem)

I wonder what that number implies for ever operating the Raptor from austere fields ? Air dominance is not an issue in Afghanistan, for sure, but let's suppose it was. Could you fly the Raptor from Kandahar and have the a/c retain its' stealthiness ?

Nostalgia isn't what it used to be.

Shmertspionem From India, joined Aug 2006, 451 posts, RR: 1
Reply 6, posted (2 years 5 months 1 week 1 day 4 hours ago) and read 4060 times:

Quoting connies4ever (Reply 5):
I wonder what that number implies for ever operating the Raptor from austere fields ?

that was never a possibility - i read during the Qatar deployment (was it this year or last?) that 6 months of prep was required by technical teams to make the deployment feasible.

Vi veri universum vivus vici

Ferpe From France, joined Nov 2010, 1785 posts, RR: 57
Reply 7, posted (2 years 5 months 1 week 21 hours ago) and read 3946 times:

As far as I understand the problem it is more complicated then the CFRP carbon interacting with aluminium.

If I understand stealth technology right you need to make sure you have a wing/body/tail etc without any join gaps as seen by the radar wave otherwise every electromagnetic gap will work as a radar reflector (small cavities full of corners and angels, compare with the radar reflector you put on the top of the mast of a sailboat).

In other words you need to make a electromagnetically totally smooth surface for every surface of the aircraft, i.e. you need to fill every join at least the ones facing forwards.

So you need a material to put in all the joints. I understand it to be some filling material with even silver flakes or alike mixed in to make it electromagnetically conductive at the wavelengths in question (X-band fighter radars). Pair this with the need to have something in the CFRP that makes contact with this conductive material to make it one continous smooth surface (could be the carbon or some conductive mesh in the CFRP) and you have very easily an "electrical battery" setup between the two materials leading to electrochemical corrosion.

So you basically have corrosion in every join on the airframe. Though it might not be structurally dangerous rust does not make great electrical contact, suddenly you have a F22 that gets gradually more visible on the enemy radar! Wow!