永利国际娱乐注册送56 会员中心 TAG标签
网站地图 RSS
英国作业 新西兰作业 爱尔兰作业 美国作业 加拿大作业
返回永利国际娱乐注册送56

代写英国硕士论文-HAROLD EDGERTON IN WORLD WAR II( The Structure of E(7)

时间:2012-05-23 14:02来源:未知 编辑:留学生作业 点击:
bomb and electronic flash. Figure 24 shows two aerial photographs, one taken with flash bomb technology and the other with Edgerton抯 electronic flash. Flash Bomb Electronic Flash Advantages ?Shadows

bomb and electronic flash. Figure 24 shows two aerial photographs, one taken with flash bomb
technology and the other with Edgerton抯 electronic flash.
Flash Bomb Electronic Flash
Advantages ?Shadows indicate heights of
subjects
?Lighter equipment
?Easy and safe to use
?Non-explosive
?Unlimited number of photos
per flight
?Operates at a range of altitudes
Disadvantages ?Number of photos per flight
limited by flash bombs on board
?Explosive material
?Operation at fixed altitude
?Problematic in inclement weather
?Heavy equipment
?Delicate bulbs
?Lack of shadow information
?Fogging of film when camera
and flash too close
Table 1: Comparison of Flash Bomb and Electronic Flash
47 Ibid, 288.
48 Harold Edgerton Papers, Box 80 Folder 6.
49 Edgerton, Moments of Vision, 138.
Figure 24: Photos Taken with Flash Bomb48 (left) and Electronic Flash49 (right)
22
In light of the advantages and disadvantages of the flash bomb method and the electronic flash
method, these two technologies served well under different conditions. Edgerton reiterates this
point, 揅ontrary to a first impression that these two distinctly different methods are competitive,
they complement each other in tactical uses.?0 His biggest challenge was not with the flash
bomb. Rather, it was with developing a technology quick enough to meet the urgent demands of
the armed forces. This is where Edgerton抯 work ethic excelled. In a letter written to Edgerton
in 1941, Lt. F.O. Carroll explained,
The probability of widespread use of flash unit for night photography is rapidly
increasing and it is indicated that the need for it will be urgent. It is therefore
recommended that the full size unit be developed with all possible haste.51
THE SIX ELECTRONIC FLASH MODELS
By the end of 1939, Edgerton had tested a quarter-scale prototype of his aerial flash in a B-18
bomber over Boston, resulting in the first photograph using aerial electronic flash techniques.
By March of 1941, Edgerton had begun testing his full-scale system over Boston, with MIT as
the subject of some of his first aerial photographs. Edgerton used these as initial demonstrations
to Goddard, who commended Edgerton for his work in August 1941:
Your flash development for aerial photography has received excellent recognition by the War
Department. They really believe that this development has tremendous possibilities, and I feel
that you should do everything possible to expedite the completion of the second unit.52
Besides his experimental trials between 1939 and 1942, Edgerton produced six different flash
units for use in aerial night photography, numbered D-1 through D-6. See Figure 25 for the
development and operation timeline for all models as well as a representation at the altitudes
50 Harold Edgerton, "The Past, Present, & Future of High Speed Photography" Journal of Physical Society of
America July 1947, 13. Harold Edgerton Papers, Box 105 Folder 32.
51 Harold Edgerton Papers, Box 77 Folder 10.
Figure 25: Timeline for Electronic Flash Development53
23
they operated at.
Each of his first three models
surpassed the previous one in
the amount of energy released
per flash. There is significant
improvement from one model to
the next, but D-1 represents the
greatest leap in technology
when compared to his pre-war
strobes. A visual comparison of
images of the Milk Drop and
Stonehenge (Figure 26)
illustrates the change in the
magnitude of flash intensities.
Figure 27 gives a quantitative
analysis of the energy per flash of the systems developed up to 1943.
The Strobotac, which was used during his consulting practices was held in close proximity to the
subject and did not require high light
intensities. The Strobotac released 0.135
watt-sec per flash, unlike the aerial
photography units where the smallest
energy level was 342 watt-sec, which
was approximately 2,500 times as
powerful. The largest flash unit was
about 250,000 times more powerful than
the Strobotac. Goddard also recognized
the challenge this application presented:
揟hey had succeeded in producing an
electric flash system for nothing larger
than a small hand-held Graflex camera,
and what I was asking for was a jump
from candlelight to sunlight.?7
Looking at the units themselves, the
differences in magnitude can be better
visualized. Figure 8 showed the
Strobotac unit manufactured by the
52 Harold Edgerton Papers, Box 77 Folder 10.
53 Synthesized from 揘ight Aerial Photography ?A Technical Story?ORDWES Laboratory, Wesleyan University,
July 1, 1954. Harold Edgerton Papers, Box 79 Folder 8.
54 Edgerton, Moments of Vision, 1.
55 Harold Edgerton Papers, Box 79 Folder 5.
56 Synthesized from Harold Edgerton Papers, Box 62 Notebook 14, p. 39.
57 Goddard, 244
Figure 26: The Milk Drop54 (left) and Stonehenge55 (right)
Energy Released Per Flash
0.135 342
3200
32000
Strobotac D-1 Flash D-2 Flash D-3 Flash
Watt-Seconds
Figure 27: Energy per Flash for Strobe Systems up to 194356
24
General Radio Company in 1935 under Edgerton抯 patent. The Strobotac can be compared to
the aerial flash units shown below. Figure 28 shows a D-3 system installed in an A-26 bomber
and the flash is being operated on the ground. Figure 29 shows two reflectors right before
installation.
In his first three units, there is an increase in energy per flash. Edgerton had to create systems
with greater energy output to enable flights at higher altitudes. Goddard explains, 揋reat altitude
to a reconnaissance pilot in World War II was money in the bank, it meant he had a much better
chance of coming home safely.?0 Delivering for this specific goal, Edgerton bettered his system
along this dimension provided that he could ready the units in time for successful operations.
Much like Draper抯 missile guidance system with increasing accuracy, Edgerton could believe in
a trajectory for his first three units. Table 2 shows the final specifications of these systems by
the end of 1943:
D-1 Flash D-2 Flash D-3 Flash
Operation Altitude
with f/1.5 Camera 1,000 ft 5,000 ft 20,000 ft
Energy per Flash 460
Watt-sec
3,000
Watt-sec
43,200
watt-sec
Capacity 75 霧
3500 Volts
375 霧
4000 Volts
5,400 霧
4000 Volts
Weight 150 lb 500 lb 5,400+ lb
Table 2: Specifications of Three Major Edgerton Flash Units61
However, the end of 1943 marks a shift as the models that follow the D-3 no longer increase
energy released per flash but rather are specific solutions to applications required by the army.
These customized solutions led to the D-4, D-5 and the D-6, which were modified versions of the
58 Edgerton, Electronic Flash, Strobe, 290.
59 Harold Edgerton Papers, Box 79 Folder 5.
60 Goddard,307
61 Harold Edgerton Papers, Box 77 Folder 4.
Figure 28: A D-3 Flash Unit in A-2658 Figure 29: Flash Units Before
Installation59
25
D-2 flash. Table 3 shows the specifications of the new units. D-4 was designed to be a
lightweight unit for low altitude flights in the South Pacific. D-5 incorporated use of standard
power inverters, which were also used in other navigational equipment like early radar. D-6 was
an improved version of D-5 that could work at higher plane speeds with less time required
between flashes.62
D-2 Flash D-4 Flash D-5 Flash D6-Flash
Operation Altitude
with f/1.5 Camera 5,000 ft 600-1,300 ft 5,000 ft 3,000 ft
Weight 500 lb 362 lb 1,400 lb 1,500 lb
Table 3: Specifications of Edgerton Flash Units Modified from D-2
Once the D-3 allowed photography from an altitude of 20,000 feet, it was no longer necessary to
pursue improvements along this dimension. Therefore subsequent models represented
improvements of the D-2 flash along other dimensions, including power requirements and
allowable plane speed.
One of the reasons the D-2 was the model in operation the longest was because it accommodated
alterations for specific purposes. In most cases, the manufactured D-3 models were reassembled
into D-2 models. Edgerton was personally involved in the re-engineering process when he took
a D-3 from Italy to England to be made into three D-2 flash units. After D-Day, sixty D-2 units
were ordered making it the most manufactured unit produced by the General Electric
Company.63
D-2 may also have lasted so long because it a fostered a good trade-off between weight and
altitude. Table 4 shows the planes that were available for reconnaissance and the units they
could carry. The table shows that the D-3 could only be used with an A-26, a luxurious
requirement during war times when planes with high bomb capacity were always being utilized
in attack fronts. Although the D-2 could not operate at the altitudes as high as the D-3, it was
nonetheless, more manageable. D-2抯 superiority over the D-1 is the ability to operate at higher
altitudes without a big impact on the weight of the unit by making more use of the plane抯 power
supply.
Admissible Flash Units
Plane Model Bomb Capacity
D-1 D-2 D-3
B-18 2,000 lb  
B-25 4,000 lb  
A-20 4,000 lb  
A-26
(aka B-24)
6,000 lb   
Table 4: Types of Planes and Flash Units They Could Carry64


推荐内容
  • 英国作业
  • 新西兰作业
  • 爱尔兰作业
  • 美国作业
  • 加拿大作业
  • 代写英国essay
  • 代写澳洲essay
  • 代写美国essay
  • 代写加拿大essay
  • MBA Essay
  • Essay格式范文
  • 澳洲66402
  • 代写英国assignment
  • 新西兰66402
  • Assignment格式
  • 如何写assignment
  • 代写英国termpaper
  • 代写澳洲termpaper
  • 英国coursework代写
  • PEST分析法
  • literature review
  • Research Proposal
  • 参考文献格式
  • case study
  • presentation
  • report格式
  • Summary范文
  • common application
  • Personal Statement
  • Motivation Letter
  • Application Letter
  • recommendation letter
  • Europe (24-hours)
    EN:13917206902
    china (24-hours)
    CN:13917206902
    在线客服团队
    全天候24小时在线客服 QQ:1455780998

    微信在线客服(24小时)

    微信公众订阅号
    XML 地图 | Sitemap 地图