The compelling object at the center of this paper is an experimental prototype of a Nazi German jet powered fighter aircraft discovered by the Allies at the end of World War II and brought to the United States for study. Designed by the Horten Brothers (Reimar and Walter), this craft with a steel structure, paper-thin plywood veneers, and no vertical tail is regarded as a design predecessor to the stealth bomber. The aircraft, a model Horten Ho 229 v3 (the third and final version of this particular airframe) was captured when it was near completion in the Gotha workshop http://airandspace.si.edu/collections/artifact.cfm?object=nasm_A19600324000 Charcoal was said to have been added to the construction adhesives to make the aircraft invisible to radar.
While always a favorite of air flight/military history buffs, this craft has never been exhibited and has been the subject of increased interest in recent years due to what the paper’s author describes as a “sensationalized” documentary entitiled “Hitler’s Stealth Fighter.” This video, available on YouTube, is replete with inaccuracies including the assertion that it is stored in a “secret government warehouse” when, in fact, its current home is the Smithsonian’s Paul E Garber Facility in Suitland, Maryland. However, it will soon be moved to another disclosed location – The Udvar-Hazy Center in Chantilly, Virginia where it will have its big reveal.
In preparation for this move, conservators at the Smithsonian NASM carried out a technical study to inform treatment protocol for the stabilization of the unstable and extensively delaminating veneers. They sought to characterize and identify the adhesives and other materials employed and, in particular, seek evidence for the presence (or apparent lack) of charcoal.
The aircraft is 55.4 feet wide with a tubular steel frame. The engine rests in the center of the craft and it is covered in a plywood skin. There is a clear canopy for the pilot. Due to complications of working on the object in its storage location, the decision was made to disassemble the damaged plywood portions to allow for treatment of the panels in the conservation lab. The composite materials that were examined and analyzed included the plywood board, structural supports and spacer blocks including the adhesives used to attach these portions to one another.
After a literature review of plywood available in Germany before WWII, reference materials were acquired for the potential materials. A sampling protocol was developed and the object and reference samples were examined under visual and Polarized Light Microscopy, FTIR, Raman, and for selected samples XRD was employed. (There may have been other methods employed that I missed in my notes– GC-MS and 3-D microscopy were mentioned in the abstract – sorry if I have omitted something significant.) The analysis was done in conjunction with the Museum Conservation Institute.
The analyses yielded some unexpected results as some of the wood sample results varied from those specified by the Horten Brothers (as reported in their interrogation). However the substitutions of European Beechwood/Scots Pine for the specified birch was not very surprising to the authors given the materials shortages at the end of WWII. The adhesives tested were identified as urea formaldehyde and phenol formaldehyde. Confirming the presence of charcoal in the black paint/adhesive layers proved elusive. The black particles were difficult to separate from the matrix. PLM examination did not support the charcoal identification and they were found to be amorphous with XRD. FTIR analysis pointed to the presence of cellulose, hemi cellulose and phenolics. This could mean oxidized or charred wood – or neither.
Plans for treatment do not include repainting damaged areas as the author mentioned a growing trend toward exhibition of aircraft in a less heavily restored state. Beech veneers will be employed in areas of loss but were unavailable in the United States in the <1mm thickness required so must be ordered from Germany. Because the urea formaldehyde has cross-linked with age and become insoluble, the conservators are not as concerned as they might have been about adding new materials when they choose an adhesive to stabilize the veneers.
Details and updates on this research project and the treatment are available on the on the National Air and Space Museum’s Airspace blog http://blog.nasm.si.edu/restoration/horten-h-ix-v3-bat-wing-ship-may-2014-update/ The Bat Wing Ship is poised to be a popular attraction when it goes on exhibit – I know my interest has been piqued by this interesting talk!
Author: Eugenie Milroy
42nd Annual Meeting – Workshop, May 28, Respirator Fit Test Lecture and Respirator Fit Testing, May 29 by appointment, AIC Health and Safety Committee
In the past year have you:
- Grown a beard to emulate your conservation idol Steve Koob?
- Participated in a juice cleanse which inspired a new pattern of healthy eating and daily lunchtime walks?
- Had a little work done ?
- Contracted Hepatitis B while doing archaeological site conservation in an exotic foreign location? (I sure hope not!)
If you answered yes to any of these questions then you are a candidate for a respirator fit test even you don’t work in a place where an annual test is required. Facial hair, weight loss or gain of 20lbs or more and any other changes in the shape of your face may mean that the respirator you have been wearing is no longer tight-fitting. Serious illness may compromise your respiratory and/or other systems making respirator use dangerous.
I trust that those reading this are already aware of the importance of protecting ourselves from the potentially harmful chemical compounds (vapors and particulates) and other irritants (such as mold) that we may be exposed to in the course of our work. Depending on the risk, such protection might be afforded in a variety of ways such as via the use of laboratory fume hood, appropriate room ventilation systems including workstation elephant trunk style air outlets, and/or personal protective equipment (PPE) such as a dust mask or respirator.
If you don’t work in a museum or other institution with a designated health and safety officer following OSHA required guidelines, you might be unclear about what kind of mask is required for a particular contaminant and even what “fit testing” means. Personally, never having been “fit tested” before, I will admit that for years I wasn’t even 100% clear whether it meant “are you fit (in proper health) to wear a respirator?” or “does the respirator fit?” Of course it means both! These days all you need do is consult the very informative AIC Health and Safety Committee Wiki to get your fill of information about respirators and so much more
http://www.conservation-wiki.com/wiki/Health_%26_Safety#Personal_Protective_Equipment_.28PPE.29
As a conservator in private practice, I have no employer checking up on whether or not I am protecting myself. Several years ago I purchased a respirator, which seemed to fit well. While wearing it with the correct cartridges for the organic solvents I was working with, I figured “If I can’t smell the vapors it must be fine.” But I was never really sure that it fit and it is important to follow guidelines about the life of your cartridges to be sure you are getting adequate protection.
When I signed up for the respirator fit test, the AIC Health and Safety committee sent me the six-page OSHA Medical Evaluation Form (mostly check boxes with yes or no) to fill out and have signed by my doctor prior to fit testing. Keep this in mind if you plan to participate in fit testing at AIC next year – you must plan ahead and have this signed paperwork in hand or you will not be allowed to be tested! This form is available for download on the wiki.
The respirator fit testing consists of two steps, both of which fulfill the annual requirements mandated by OSHA. First, a brief Powerpoint, given by James R. Smith, Safety Coordinator at the Smithsonian Museum of Natural History, covered topics from the requirements of the Respiratory Protection Program (29CFR 1910.134) to hazards requiring a respirator, how to choose the correct respirator, care and maintenance, donning and doffing and training requirements for employers. The lecture was accompanied by handouts prepared by AIC Health and Safety and we were given a 10 question true or false quiz at the end.
I had scheduled my fit testing appointment prior to traveling to San Francisco. AIC Health and Safety asked participants to choose their top three time slots on the given date in order of preference. When I arrived, I noticed that there were still a couple of time slots available. I would highly recommend pre-registration for fit testing at AIC if you plan to do it next year because then you are guaranteed a spot.
The fit testing itself was quite simple. After donning my mask, James handed me a card with a poem to read while moving my head up and down, side to side and in a circular motion.
While I read this rainbow poem, he followed me with a little pen like device emitting an irritant smoke. I believe that the finale required bending at the waist. The test was brief and painless and I was relieved to hear that I had passed – particularly since I had already used the respirator on numerous projects. Once the test was over, James offered to prove to me that the respirator worked by allowing me to experience the irritant sans respirator. I declined saying that I trusted the test. However, he said that some people like to have proof and offered again. Somehow I took the bait and learned first hand that indeed, the gas is an irritant and my respirator is working properly.
Thank you to James, Kathryn A Makos, MPH, CIH (Industrial Hygienist (Ret.) Smithsonian Institution) and the rest of the AIC Health and Safety Committee for offering this service at the annual meeting.