Warbird Information Exchange

A question for those of you who are restorers (or possibly even employees of these air museums):

I know the Natl Air & Space Museum restores their aircraft to a very high degree of originality, and they emphasize preservation. And I know they overhaul the engines to where they look like new. So that got me to wondering... obviously certain systems need to be *moved* to be best preserved; for example, I assume you'd want to at least pull the props through every so often, etc., rather than leaving those beautiful engines in a frozen position for decades.

So my question: do they have an ongoing, active maintenance routine for aircraft on display? If so, what kinds of things are done on a timely basis? I've never seen them actively working on exhibited aircraft - do they just let them sit there, and then assume that in 20 years or so they'll go revisit the airplane again? Clearly, airplanes hung from the ceilings can't be easily dealt with. (I'm thinking about both the NASM in Washington, as well as the Udvar-Hazy Center).

I had the same question about the National Museum of the USAF in Dayton (my personal favorite museum, btw).

Thanks in advance for any insights.

They don't turn the props, there is preservative oil in the cylinders and turning the prop will wipe it off, when they make intake gaskets they leave them closed to seal the engine, They install spacers in the gear so no oil or nitrogen is needed, and I would think they have something inside the wheels to make them solid.

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Matt Gunsch, A&P, IA, Warbird maint and restorations
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from a lot of their preservation pages NASM does the following as additional preservation; engine exhaust seals are solid except for a pin hole to prevent a vacuum from forming, engines are coated with a preservative that is flexible, yet prevents corrosion. Propeller keys are removed (to allow the props to turn, but not the crankshaft), landing gear struts have nitrogen removed and a spacer added, tires are filled with a non-hardening rubber solution. Rigging is close, but not tight to take the stress off the structure.

The NASM has been getting away from a hard restoration and more towards a soft restoration - a hard restoration would involved a 100% teardown and fix all damage repaint as new. A soft restoration is pretty much a cleaning, remove corrosion as long as it does not damage the artifact and generally clean the exterior with cleaners that will not damage the original paint. Any paint added (touch-up) is done in a manner that it can be removed easily. Electrical / hydraulic / soft rubber lines are preserved as is, generally photographed, cleaned, if the electrical cable are cracking, a wax based preservative is painted on to preserve what remains.

Any new parts manufactured in house is marked with NASM, the date and a serial number and recorded as not original.

NASM has moved to treating these aircraft more as a antique painting then a piece of machinery. When they take any original fabric off, this material is preserved.

This is just a general overview of the current policy at NASM, my suggestion is pick-up any of the NASM books (http://s158018161.onlinehome.us/1114pop/DSC00453.JPG)

Thanks for all the info. In fact, what inspired my question was that I just read their book, "National Air and Space Museum: An Autobiography", which was great about the history of many of the artifacts, but being published in 2010 wasn't current on their restoration practices. And I've also been following their restoration of "Flak Bait" (definitely using the softer approach you mention) with great interest, because both my mother and father worked at the Martin plant during the war, building B-26's.

There is a microcrystalline wax called "Renaissance Wax" that is used in museums to protect artifacts, and I believe they use that in many cases. For example, I believe it is the material referenced on the bottom of this page about the treatment of the Wright Flyer.

The book you want to pick up is Restoring Museum Aircraft by Robert C. Mikesh. Their blog post on "Restoring and Preserving Aircraft" also has some excellent information on their practices.

It's funny that you mention NMUSAF, the propellers on their Mosquito have labels specifically warning against turning the engine over:

(Source: Wikimedia Commons)

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Tri-State Warbird Museum Collections Manager & Museum Attendant

Warbird Philosophy Webmaster

I don't believe the NASM & NMUSAF collaborate on much or necessarily use the same protocols, based on conversations with both. The prop decal in the above post is one example. The insertion of a spacer in a shock strut at NASM and the intentional compression of all struts at NMUSAF is another.

Ken

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"Take care of the little things and the big things will take care of themselves."

Gotta say that I strongly disagree with any "soft restoration" technique. That just seems lazy.

The most glaring example would be the Ho-229 V3. The artifact is in such poor condition from improper storage for decades, and moisture and fungal rot. The wood is literally just powder in places. What is goal to preserve what is arguably neglect rather than returning the aircraft to represent what it was? I have looked at the careful work being done to restore the rotted wood, but I think replication would be a better method for long-term preservation. It's almost like a bondo job for a vintage car. I believe that the Ho-229 was given a spurious paint job by the Allies and it would be better to return it to the condition it would have been if it had been completed in the Gotha shop - natural wood or just the fireproof layer of paint.

Also look at the Ta-152 that had been given occasional repair work for years. Like the Ho-229, the Ta-152 does not even have factory or service paint on the outermost layers of paint. The Allies painted these captured aircraft multiple times. The only real way to return it to wartime condition would be a careful strip to document the correct paint and then redo it.

I fail to understand what is accomplished with "soft" restorations.

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"They done it, they done it, damned if they ain't flew." December 17, 1903

I agree!

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Ain't no sunshine when she's gone!

I think you have to pick your subject carefully.

Flak Bait is practically a time capsule. It requires very little more than careful cleaning and preservation.
I agree with the TA-152. If there is little left of the original then restore it as close as possible to operational.
He!!, I want to see the TA-152 fly!

It is definitely possible to go too far though.
Memphis Belle is an example of a 25 mission B-17 that looks basically brand new.

The final thing that you will have to accept is that you will never please everybody.
The argument that something can only be original once weighs heavily in to the "soft restoration" / preservation category.

Andy

Belle was in poor shape from the years at Mud Island, plus outside storage, vandalism, and a 1980s repaint. So I think the only choice was major work.

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"They done it, they done it, damned if they ain't flew." December 17, 1903

another example is Shoo shoo Shoo Baby - the 1980's restoration was an abortion (good for the 1970's but very poor for Smithsonian standards) and the only way NASM can get her to their standards is a full tear down - which is one of the reasons Ol Betsy was traded so that NASM did not have to do much work to present a B-17.

As far as the Horten, yes and no, if the NASM did a full restoration as suggested, there would be hardly anything original on the ship and would defeat NASM standard of preserving as much original as possible. If you want to see the soft approach, one just has to look at the NASM P-38 (all original) or P-61. Both are stunning examples of time capsules of untouched original WWII paint and building techniques.
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There is a major difference between restoring for flight or restoring to preserve something for 200+ years -- the later is what NASM is intending
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As far as Memphis Belle, I miss her McDill AAF markings.

Hardly lazy. I could argue that "soft" restorations (i.e. conservation/preservation) take more effort than a "hard" one. Flak Bait is a great example. The amount of effort that went in to just conserving the rudder fabric is huge. Many comparable "hard" restorations would have completed a lot more in the same amount of time.


By the way, NASM has an excellent page all about their preservation of the Ho 229 if anyone is interested.


I would like to point out that this has been done on a number of occasions. Specifically, the Fleet Air Arm Museum's Corsair KD431 is an excellent example. I believe they discovered something about fallout detecting paint that would have been lost otherwise. The abstract on the Google Books page on the book about the preservation provides a good justification for this approach.


Well, as you likely know, the most famous aspect of the Ho 229 is it's supposed (and likely false) stealth capabilities. A "hard" restoration would eliminate any evidence of that.

Besides, there are far, far more "hard" restorations in the world than "soft" ones. Why not be satisfied with those? That's what bothers me when people suggest that NMUSAF should fly, say, their P-51. Are the 100+ flying in the United States alone not enough for you? (I don't mean to direct this last point at you specifically D9, so I hope you don't take it personally.)

Furthermore, having an original, preserved example means that you always have a "holotype" to use as a basis for a future replica. If someone wants to go built one (as they did with the Ho 229) the primary source artifact is available.


Agreed. The situation is different for different airplanes, and there is no one-size-fits-all approach.

EDIT: Fixed the broken link.

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Tri-State Warbird Museum Collections Manager & Museum Attendant

Warbird Philosophy Webmaster

As was already pointed out, Flak Bait is basically an untouched time capsule and worthy of any effort to preserve it in its current state. I would argue that the Ho-229 lost much of it's originality once the Allies finished construction on the example and slapped blue paint all over it. The NASM is doing fantastic work on the Horten, but if the goal is to leave the blue paint (and I hope that it is not) then it doesn't represent the original artifact. When captured the completed parts were paint green or unpainted.

If the almost complete He-219 is an example of a "soft" restoration, then I support the Ta-152 getting the same treatment. They have done an excellent job with the He-219. The Ta-152 deserved to shine as a final WW2 example.

The preservation work they are doing is fascinating if not revolutionary. The 229 is in terrible shape and is a mass of delaminated, crumbling wood almost as if beetles have devoured it. I am unsure if the work being done to stabilize it will hold over the decades, or would it have been better to recreate the structure and archive the original wood separate from the display. I just don't agree that pickling rot and corrosion is the best approach.

I have read the NASM website on the 229 conservation. They conducted lab samples on the wood to look for any "stealth" built into the aircraft. I think the stealth by design theory has been settled once and for all. There are accidental stealth properties in the aircraft but that was not why it was built. Also the model built by Northrop for the radar study is not a replica at all. The model department at Northrop constructed a wood and fiberglass shape to represent the 229 and it was not a copy of the aircraft.

A few pictures of the 229 remains show what the NASM is trying to conserve. It is a mess and they have an uphill battle to save it. It's only my opinion that precise reconstruction would perhaps be a better way to save and display the plane.

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"They done it, they done it, damned if they ain't flew." December 17, 1903

In a hypothetical, perfect world, going forward there will be no more restorations, only preservations, as items will be marked for museums while still in service and will all enter collections as time capsules. The best example at present is the NMUSAF MH-53; flown in combat in Iraq and delivered to Dayton in a C-5.

In the real world, however, we have artifacts that can be preserved, some that must be restored to varying levels, and ones that would have to be fully recreated to be seen.

The biggest impediment to all of this: funding. I'm too lazy to do the research, but I'd be fascinated to see the annual budget of our National Museums since 1950 to see what their purchasing power has been and what they've accomplished with those dollars. The Serian and Enola Gay come to mind as standard-setters, others not so much. The backlog of projects is staggering and, without copious funding, soft restorations become a necessary evil.

Ken

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"Take care of the little things and the big things will take care of themselves."

Can you re-post that link? It doesn't work for me.