Future Maintenance - today's warriors vs. yesterday's

[ww2John]

This thread is NOT about a particular service or country's refusal to sell contemporary or near contemporary military aircraft to civilian owners for flight or display. If you want to bash those policies, please start another thread.
This is a sincere question about future maintenance on contemporary military aircraft IF they were ever to be allowed in civilian hands.
It seems to me that there are many contemporary military aircraft that are/were constructed using rather exotic materials, using rather exotic construction techniques, very specialized tooling & tools, etc. What got me started thinking about this was watching some vintage Lockheed footage showing them building the SR-71/A-12. Wow. Talk about exotic. Not that any civilian is going to own and fly an SR-71, but...
There are other fighter and ground support a/c that use materials and construction techniques far different from the WWII, Korean & Vietnam warbirds we see restored and operated by civilian entities today.
For the sake of discussion, lets suppose that an a/c like the F-22 Raptor was ever released to the civilian market, and assuming that $$ were not the major obstacle (in the context that today, if you have enough money for materials and personnel you can take 3 wrecks recovered from Russia and build a flyable P39), is it in the realm of possibility that a civilian owner could keep a Raptor flying 40-50-60 years from now? Or are the a/c materials, tooling, etc. in modern military a/c so exotic that it could not be feasibly maintained/restored/flown regularly?
Just wondering and not trying to start bashing (please see first sentence).
Thanks,
John

[PropsRule]

Perhaps not the materials, but the processes required to construct and maintain parts made from them are/can be exotic. I'd much rather build an all-aluminum vertical stabilzer for a P-51 from scratch than one for an F-22 out of carbon fibre.

I *have* made carbon fibre motorcycle parts, but they were all non-structural so it was relatively easy to just lay them up in my garage without worrying about temperature and pressure.

[The Inspector]

The more modern the piece of equipment, the more likely it is that when it's life use is done all the military would need to do is remove the electronics and wire bundles and crush them and make a couple of strategic cuts to the structure, and VIOLA!!! one permanent gate guardian.

As far as disposing of the carcass, you don't need dramatic cranes dropping blades, you simply cut it up, grind it up, heat it in an autoclave to an incredible temperature to burn out all the matrix and impurities and make new tape or weave out of the result.

Modern aircraft larger than private twins are pretty much all flown electronically (fly by wire/fly by light). The 777 only has rudder back up cable connected to any flight control it's fly by wire for all primary controls and the only cables on the 787 are the ones you would pull to dump the toilet tanks, so making a modern warplane inert is pretty simple!

Building structural CFRP components requires an autoclave (the bigger the part needing repair, the bigger the autoclave as it all has to go in to make the repair) and some fairly sophisticated engineering and knowledge of carbon fiber tensile properties, those can be learned but making the repair and making it safe are another can of worms. Right now, Boeings AOG (airplane on ground) repair folks and AOG engineering are learning as fast as they can how to repair a 787, simple things like the type of lights in the hanger can degrade the matrix in unprotected (primed or painted) CFRP and make it useless. They come over and chop pieces out of our training section and figure out the physical repair using our parts.

It quickly becomes a matter of scale and cost, and the bigger the scale, the less likely you can afford the cost, so accept that you or your kids will never be able to put a surplus F-22 in the air.

[ZRX61]

Perhaps not the materials, but the processes required to construct and maintain parts made from them are/can be exotic. I'd much rather build an all-aluminum vertical stabilzer for a P-51 from scratch than one for an F-22 out of carbon fibre.

Somewhere in my garage are some composite scrapers that used to be part of an F117 vertical If you drop them on a hard surface they sound like tin.....

I don't think the composite parts are going to be a problem *if* they start letting civvies fly F22's... it's going to be the Ti parts...

[The Inspector]

CFRP is basically just a really stiff piece of blanket, either woven or unidirectional tape and I'd be more concerned about UV A and UB B degrading the matirix than I would be about the Ti. I'd also be careful of slivers and splinters especially as the CFRP gets older, CFRP slivers, if not removed NOW can lead to E.R. mini surgery to lance open you finger and find/remove the smaller than a spiderweb slivers of the stuff before it becomes infected.
Ti has no known fatigue life and won't take a 'set' as steel or aluminum will. Bend a strip of Ti and it comes right back to where it was no matter how many times you bend it. One of the things the guys in the black suits discovered was that the SR-71 got better the more you flew it.

[ZRX61]

CFRP is basically just a really stiff piece of blanket, either woven or unidirectional tape and I'd be more concerned about UV A and UB B degrading the matirix than I would be about the Ti. I'd also be careful of slivers and splinters especially as the CFRP gets older, CFRP slivers, if not removed NOW can lead to E.R. mini surgery to lance open you finger and find/remove the smaller than a spiderweb slivers of the stuff before it becomes infected.

Tell me about it Odd thing about CF splinters is the black spec with the red rash around it looks EXACTLY like an anthrax sore (I worked part time for Hudson Bay many years ago, there were posters all over showing what to look for). Another hazzard from CF is inhaling the dust from sanding, VERY bad ju-ju! I started on composites with Ciba Geigy at Duxford (on the other side of the M11 to the usual place) back in the '80s. I prefer aluminum

Local Community College here teaches aerospace composites & Northrop have been hiring EVERY graduate that can pass the background check.

My comment earlier about the Ti V CF was more about the expense of fabricating replacement parts: Composite repair/fab is fairly straighforward, Ti can be a bit of a bugger.

[JDK]

It's an interesting question. Just going in a different direction to the technologically literate above...

At the end of W.W.I it was said that civilians wouldn't be able to operate an SE5a (the F-22 of its day). A doctor in Southern England used it as his runabout on his rounds in 1920.

When the Harrier was coming up for retirement, the word was it was never going to be a private civilian operable aircraft - good on Art Nalls!

I'd have said that a non air force operated four-engine five-crew nuclear bomber was not viable. Wrong again.

No comment on structures with these, of course - technically all are 'conventional' in their day - but analogue complexity in a degree we can understand with the Harrier, which in essential terms was the same in its day for the SE5a.

That said it would be interesting to plot relative costs (fuel per hour, say) and see if the graphs show an exponential growth.

Current lunatic fringe wishlist here in Australia is for a display F-111, after their recent retirement. It won't happen due to US Defense requirements and cost - despite the complexity it could be done, but the old cost-benefit is just beyond any market.

Again, you could see a maintainable hours (or number of personnel required) growth (per hour flight) and equipment infrastructure requirement. In that we can see the growth of what really is 'high technology' from the SE which could be maintained in part with carter's tools, wheras very little of the Harrier or Vulcan can be maintained with even standard aeronautical equipment - as far as I understand that is?

Just a few thoughts,

[RickH]

We have a quote posted inside the nosegear door of the F-4.

"The Impossible is Possible ! "

More than one skeptic said these would never fly !



But having said that, these are of more conventional construction. Even the honeycomb is repairable using fairly straightforward techniques.

[The Inspector]

I agree that older, more 'sheet of tin' aircraft can be brought back with enough money and time but both the A4 and the Rhino are mid 50's design technology. If, forty five years from now someone stumbled onto an abandoned EUROFIGHTER airframe that had been completely stripped of all it's wiring and electronics and computers, it most likely couldn't fly again as that individual would need to design and manufacture computers and wiring harnesses and connecters to make the flight controls operate, and the airframe would have most likely have been 'de-milled' with DOTCOs making safe repairs all but impossible to the average guy. "Tom, I'm gonna turn the two car garage into a big autoclave" won't happen unless you are Paul Allen. Nothing is impossible, but I doubt that TITANIC will ever make port. There is a vast ocean of difference between the good Doctor patching his SE5 with a shirttail and some pot glue and doing the complex math of how many laminations and in which specific directions in what order, under what heat and pressure you need to repair the big hole that was cut out of your newly aquired CFRP jet hulk.


I'm concerned when I see that Ben DeBumpa has smacked the barriers in his F-1 ride, tearing off all the suspension and destroying the right side of the car, yet it's back on the grid the next morning. I don't recall seeing Peter Matchett showing us the portable autoclave that FERRARI carries around to each race to do proper repairs. As the driver, I'd be pretty spooked about climbing into something that was repaired using duct tape to hold the parts while the bonding was agent cured overnight by a mechanic using a handheld heat gun and then going 200+ MPH but then I have at least a rudimentary understanding of tensile strength and shearing forces.

Basically, a MORGAN +4 and a MAZDA MX 5 are both sports cars, one can be fixed and maintained with little more than a pair of pliers, a keyhole saw, a screwdriver, and a small hammer. The other one is so computer reliant and computer driven that Joe Average cannot maintain it properly tuning it 'by ear' old, Flintstones technology vs. computer driven technology. Example, if the 'check engine' light comes on in your new car, it's usually because you didn't screw the gas cap down tight enough last fill up, you can go to the dealer and have it reset with a computer plug-in or tighten and loosen the gas cap yourself about 95 times to reset the sensor, but, since the gas cap is part of the closed loop system of the powertrain, the sensor gets activated.

[PanzerJohn]

Theres a pair of ready to go Su 27 Flankers for sale here..

http://www.prideaircraft.com/flanker.htm


now they are fairly hi-tech.

[ZRX61]

I'm concerned when I see that Ben DeBumpa has smacked the barriers in his F-1 ride, tearing off all the suspension and destroying the right side of the car, yet it's back on the grid the next morning. I don't recall seeing Peter Matchett showing us the portable autoclave that FERRARI carries around to each race to do proper repairs. As the driver, I'd be pretty spooked about climbing into something that was repaired using duct tape to hold the parts while the bonding was agent cured overnight by a mechanic using a handheld heat gun

Next time you're in the UK go take a look around an F1 shop....

[The Inspector]

I understand the ones in the race shop, my statement about good old Ben misplacing turn 6 addressed repairs at the track, does Williams carry an autoclave to Singapore to do 'at site' repairs? Do they fly the wreck back to the shop, fix it and fly it back overnight? I'd guess that answer is "NO". I seriously doubt that any F-1 team would allow any of the 'great unwashed' into their race shops just because you 'thought it would be cool to look around' remember the big stink (and huge fine) over Williams having Ferrari info a couple of years ago?

[PanzerJohn]

F1 teams don't fix, they replace.

[dhfan]

That's right, if the tub's damaged they rebuild the car around a new one.

Before even getting into composites, go back another generation. At an open day at DH at Hatfield in the early 80s I saw huge lumps being chomped out for wings of some sort, Airbus or 146 I guess. Could anybody afford to buy a lump of aluminium the size of a house, mill 98% of it to swarf, and turn it into a wing skin?

[ZRX61]

That's right, if the tub's damaged they rebuild the car around a new one.

Before even getting into composites, go back another generation. At an open day at DH at Hatfield in the early 80s I saw huge lumps being chomped out for wings of some sort, Airbus or 146 I guess. Could anybody afford to buy a lump of aluminium the size of a house, mill 98% of it to swarf, and turn it into a wing skin?

You should see the "milling machine" Rutan has at Mojave.

ok, found it, It's not quite as big as I remembered:
50x20x8ft
http://www.scaled.com/services/cms_mill.html