Hmmm. Some good points shoring up personal preferences here.
A starting declaration: I've a lot of time for both the fliers and the static museums, provided they're doing as good a job as they can. But
Both also have compromises.
Any airworthy warbird has compromises in terms of systems that aren't servicable as they aren't needed in civilian life, dummy guns, modern nav aids (hidden or not) and so on. The stuff that needs to work (engines, flight systems) does; but they'll be working using modern materials, which aren't original. All fine, but let's not kid ourselves it's like it was 'back in service'. The bonus is it flies, and can do was a non airworthy aircraft can't do, which is demonstrate some of it's operational capability. But again, there's an issue ducked here which is that it's 'part'. They don't demonstrate an actual strafing attack or bombing raid. You can't get the safety signoff.
On the other hand, as RickH has pointed out, national collections like the NASAM substitute non-original non airworthy parts, clearly marked, where necessary, so the aircraft is as complete, representative and original as possible.
This objective is a pot winning bonus, not the
aim of a flying warbird.
The RAAF Museum is currently restoring and conserving a de Havilland Mosquito PR.XVI. (it's a real one, btw, rather than a B.35 pretending to be a PR. XVI, as the NMUSAF has...) The undercarriage, engine bearers, props are all original to that aircraft; they've been NDT tested (will they bear the weight for 50 years?) conserved so they are stable for that 50 years, and go back on. In 50 years you can look at the aircraft, in detail, and it is as original as was built by DH and as used by the RAAF as the conservators and restorers can do. It would be much easier, and prettier to take NOS parts, or airworthy parts for the aircraft, but they aren't part of that aircraft's history. As long as the hoses and cables are stable, they can be reused; it has slothead, not crosshead screws in the wood. Some of that
can't be done with a flying warbird and other items are
unnecessary.
Museums which have incomplete of badly document aircraft are failing in their job of preservation for future generations. They should strive to get good parts to complete the aircraft. Generally, they aren't competing with people flying the type, but sometimes it does happen.
I think we started with a modification for flying safety (new brakes) which when an aircraft goes into a museum is both a waste and misleading - the right type of original brakes should be fitted; in an ideal world.
It's not about 'fooling the casual visitor'. This isn't a concors or show; it's providing accrurate, properly preserved artifacts for our great grandchildren. We don't know that a Mosquito or F-4 Phantom will be flying in 2100, I hope so. But we should have
properly preserved versions in museums, not shells.
Rick takes a cheap shot at the static museum's aircraft 'decaying' aircraft, which is sometimes fair comment. Speaking as one of the guys who helps clean the RAAF Museum aircraft, which were stabilised before going on show, so decay is minimal (and significantly slower than on an airworthy machine) that's not true of the top level museum. An active aircraft consumes parts, requires significantly more funding to maintain than a static one, and can be badly maintained as well, in some cases. Thankfully most operators are far beyond that today.
Engines. When the RAF Museum's B-17 flew into the UK, after it landed 'for the last time', its airworthy engines were swapped with time-expired examples on the flying B-17,
Sally B. A win win, and perfectly good engines suiting each aircraft. The Aviation museum at Moorrabbin, Victoria, Australia, has a complete Bristol Beaufighter. THe Hercules engines were regularly run up until the 1980s. They are not for sale, as they are original to that aircraft as built and used. It may be disappointing, but the engines belong to them to do as they wish with (or not.) (This is my understanding. I may be wrong, but the scenario stands.)
Finally, if I may, restoring an aircraft 'to airworthy' as some kind of 'best' and then sticking it in a museum is
generally absurd. By doing so you are junking a number of parts which go with that aircraft and are original; and you've compromised that aircraft's historical value. By all means fly it 'once' to prove it's airworthy (Shearwater Museum in NS, Canada did with their Swordfish) and it's a buzz for the restorers, and a great idea; but at least 25% of the work (and tons of paper) is wasted thereafter on what is a static machine.
I don't understand why so many people bang on as though we should have 'just static' or 'just flying' aircraft. For the foreseeable future we'll have both, doing different jobs, and complimenting each other's roles in history and commemoration. Just accept it, it's better than the alternatives anyway, surely? It takes a zealot or a m0ron to believe only one of the extremes is 'right'.
Ducks, runs...