A short clip brings you inside the cockpit of a B-52 strategic bomber flying a nuclear alert training sortie. And one of the coolest things is the scene showing a pilot wearing the PLZT goggles.
For the first time in modern history, cameras were allowed to enter the cockpit of a B-52H Stratofortress strategic bomber flying a nuclear alert training mission.
FIlmed by Dallas-based film producer Jeff Bolton, who recently filmed aboard a flying B-2A Spirit bomber, the new video, available at JeffBolton.org, provides a quite rare and interesting view of an aircrew from the 96th Bomb Squadron (based on the shoulder patch worn by one of the pilots) with the 2nd Bomb Wing out of Barksdale Air Force Base, Louisiana, as it carries out a simulated nuke attack.
Although quite short, the clip shows several interesting details: the nuclear weapons panel, the front panel and the nav station and, above all, it provides a glimpse at the rare Polarized Lead Zirconium Titanate (PLZT, pronounced “plizzit”) used by the B-52 pilots to protect their eyes from injuries caused by the initial thermal flash from a nuclear blast. It’s probably the first time I see these goggles worn in-flight.
As explained in details by Steen Hartov in an article published by Flightgear On-line (one of the most famous websites among flight helmets collectors and one of my personal favorites on this topic for years), nuclear detonations would cause “Flash blindness” making extremely difficult, if not impossible, for a pilot, to handle the aircraft for some time. Just imagine the impact of a temporary blindness on an aircrew flying in hostile environment who are not able to read instruments and operate systems.
“This flash swamps the retina, bleaching out the visual pigments and producing temporary blindness. During daylight hours, this temporary effect may last for about 2 minutes. At night, with the pupil dilated for dark adaptation, flash blindness will affect personnel at greater ranges and for greater durations. Partial recovery can be expected in 3 to 10 minutes, though it may require 15 to 35 minutes for full night adaptation recovery. Retinal scarring is the permanent damage from a retinal burn. It will occur only when the fireball is actually in the individual’s field of view and should be a relatively uncommon injury.”
Hence the need to use PLZT protective devices on the dual visor housing of an HGU-55 flight helmet (HGU-55E). Here’s another excerpt from Flightgear.dk website:
“The most advanced thermal flash protective devices in use are the PLZT goggles. These goggles are made of sandwich composite of polarized glass with an inner layer of a transparent electro-optic ceramic called PLZT. When linked to an electric current, the lenses are clear. But any dangerous flash of light, such as lightning or a nuclear blast, instantaneously breaks the circuit. This causes the lenses to go black, protecting the vision of anyone wearing the helmet. The designers of the PLZT goggle had found that the material could be discharged quicker than when charged to change the transmittance. Unfortunately, in order to obtain the desired switching speed, this meant that when the nuclear flash protective goggle failed, it was basically opaque.
PLZT is a ceramic material consisting of lead, lanthanum, zirconate, and titante and it can be electronically switched rapidly in polarity, such that when sandwiched with a near infrared blocking material and a fixed polarizing material, the visual transmittance can be varied from full open state (approximately 20%) to totally opaque within a ten-millionth of a second.
The protection device ( helmet-mounted special goggles containing four lenses) was developed under a $7.2 million contract managed by Aeronautical Systems Division at Wright-Patterson AFB, Ohio. The requirements for the goggles was orchestrated by Cal Crochet, SAC Life Support System program manager, who was the direct interface with Sandia Laboratories at Kirtland AFB, NM. The idea for the goggles came from Cal’s experience during his early days of flying helicopter (1957) at Eniwetok Atoll during nuclear tests under “Operation Hardtack” and later from his experiences with the flash curtain, gold goggles and eye patch problems encountered as a SAC B-47 and B-52 aircraft commander with the 306th and 509th Bomb Wings.
The PLZT material was developed by two engineers, Gene Haertling and Cecil Land, from the Sandia National Laboratories in New Mexico from 1961 to 1973 (U.S. Patent No. 3,666,666, May 30, 1972, “Ferroelectric Ceramic Materials”).
What initially was a visor lens for B-52 pilots was later refined into glass that fit entirely within the viewing ports of an airplane cockpit, with 6-in. diameter shutters in the viewing windows.
The original PLZT goggles, military designation EEU-2/P, were developed for nuclear bombers such as the B-52 and B-1 in the Strategic Air Command (SAC), where the crewmembers would hopefully be just outside the blast, radiation, and/or heat damage radii of the weapon. A later version was designated EEU-2A/P, the difference between them being that the EEU-2A/P changes to dark faster than the EEU-2/P. By 2003 Thermal Flash Protective Devices (TFPD) were required for all PACAF aircrews on SIOP missions. Either the MIL-G-635 or PLZT goggles at the wing commanders discretion would satisfy requirements for TFPD. On aircraft that were PLZT modified, it was recommended that the PLZT goggles be used.”
Make sure to read the whole article published at the Flightgear On-Line for additional historical details and some more photo of the nuclear flash protective devices.
Interestingly, the EEU-2 goggles are also in use with the B-2 Spirit. Here’s some detail about the way they are deployed operationally in the stealth bomber according to our friend Tyler Rogoway at The War Zone who talked to a source familiar with the Spirit:
“A source intimately familiar with the B-2 described how the goggles are deployed operationally. They’re kept sealed (they are a one-time use kind of gear) and there are limited numbers of them remaining in USAF stocks. Although pilots generally do not train with them on while flying, they do go through an orientation to familiarize themselves with the process of attaching them to their helmet, and to experience what it’s like to see through them. Our source described them as similar to wearing “thick glasses” with a limited peripheral view, but they aren’t extremely heavy and would in no way keep a well trained pilot from flying the aircraft proficiently during combat. An eyepatch was also provided to cover one eye; the idea behind the eye patch being, if the goggles failed to activate when a blast went off, one eye would remain usable.
In addition to fielding EEU-2/P goggles, the B-2 was also designed to accommodate a removable glass pane that mounted above the cockpit dash that would work just as the goggles do, turning opaque to protect the crew’s eyes during a flash. The glass pane leaves the dash inaccessible and it is supposedly easy to lean into if you forget it’s there when fitted. Even with this setup, during a nuclear operation the goggles would still be worn as a backup should that system fail. The technology described was originally tested on the B-1, but did not find its way its way into the aircraft operationally, but a modular version of it seems to be alive and well in the B-2.”
Ok, with all the required background information provided above and without further ado, let’s have a look at Jeff Bolton’s B-52 clip (BTW if you find some other interesting detail I may have missed, please let me know!)