F-35 avionics system

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r3mu511

New Member
Was reading up on diffraction (and hunting for some info on Northrop's work) and came across the textbook "Fundamentals of the Physical Theory of Diffraction" by Ufimtsev, which had a foreword by Kenneth Mitzner (who worked on the B-2 for Northrop), in which he said (in the quote "PTD" refers to Ufimtsev's physical theory of diffraction):

At Northrop, where I worked on the B-2 project, we were so enthusiastic about PTD that a co-worker and I sometimes broke into choruses of “Go, Ufimtsev” to the tune of "On,Wisconsin." At both Lockheed and Northrop we referred to PTD as "industrial-strength" diffraction theory...
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So it seems at least for the B-2, Northrop shifted to using Ufimtsev's methods to numerically approximate RF scattering.

There are alternative methods for numerical approximation of RF diffraction which like PTD account for the contributions from edges/discontinuities, but have more limitations than PTD. One method was devised by Joseph Keller around the early 1950s, called the "geometrical theory of diffraction" (GTD, and it's extension the "method of equivalent currents", MEC), but I haven't found any traces of a possible link of Keller's work to Northrop during their pre-B-2 development (ie. XST project).

For the timeline in question (1950s-1970s) published numerical solutions to RF scattering (which included edge/discontinuity effects) were either PTD or GTD based, so I'm really curious as to what Northrop might have been using for their pre-B-2 XST development.
 
gf0012-aust

gf0012-aust

Grumpy Old Man
Staff member
Verified Defense Pro
r3mu511 said:
For the timeline in question (1950s-1970s) published numerical solutions to RF scattering (which included edge/discontinuity effects) were either PTD or GTD based, so I'm really curious as to what Northrop might have been using for their pre-B-2 XST development.
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you also have to factor in the unmanned developments - and a lot of the RCS minimisation discoveries were also accidental side effects.

in the 50/60's they literally were using chicken wire and tar for blending and signal absorption
 
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r3mu511

New Member
^yup, definitely agree they had empirical, accidental, or even trial-and-error based techniques... but I have to admit I am more interested in what could be Northrop's historical numerical/theory-based method of RF scattering approximation used in their pre-B-2 project (ie. what was the computational model of the software @swerve mentioned which Northrop were using at the time)...
 
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USAF77

Banned Member
Interesting reference to the British Canberra. In the early '50s being able to fly a bomber at 70,000' was about as LO as you can get, tho that was a record altitude and not typical. But I get fuzzy thinking about cause I saw one of USAFs last operating ones on the tarmac, set for recce, in '79 during the Iran hostage grab.

Looking at its form ir seems that the English designers had radar LO in mind when they built it. Is that true?


gf0012-aust said:
look at the first 4 american manned versions of stealth aircraft - all take unique approaches to the platform design - all use different approaches and design philosophies

ditto for every unmanned development

http://www.defencetalk.com/forums/air-force-aviation/brief-history-lo-10856/
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gf0012-aust

gf0012-aust

Grumpy Old Man
Staff member
Verified Defense Pro
USAF77 said:
Looking at its form ir seems that the English designers had radar LO in mind when they built it. Is that true?
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the key phrase is LO.

in the late 40's through to late 50's it was about penetrating russian air space and being able to defeat their defensive systems. LO as a construct was not on the lexicon

the US tried doing this initially with aircraft such as the B45 but they were sitting ducks. The Canberras were able to penetrate high and fast and the russians had nothing that could intercept them at either the platform or weapons system level

in fact its easy to establish that the success of the canberra drove russian missile developments from the mid 50's on

the USAF actually ran rebadged RAF canberras for a number of years until they started delivering their own modified licensed versions
 
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USAF77

Banned Member
Thanks for the reply. That B57 was at an air base in S/E Turkey in Nov. 1979 right after our Hostages were taken at that embassy. Rigged for recce. I always wondered why we used that plane. It was the only time Ive ever seen one.

Looking at its Lines it always seemed to have fewer sharp angles, except of course for the tail. And since the Brits were on the cutting edge of radar at the time I always thought "maybe" it was designed to bounce less radar then other era war planes. Most of all because of its recce mission profile, along with that of a bomber.


gf0012-aust said:
the key phrase is LO.

in the late 40's through to late 50's it was about penetrating russian air space and being able to defeat their defensive systems. LO as a construct was not on the lexicon

the US tried doing this initially with aircraft such as the B45 but they were sitting ducks. The Canberras were able to penetrate high and fast and the russians had nothing that could intercept them at either the platform or weapons system level

in fact its easy to establish that the success of the canberra drove russian missile developments from the mid 50's on

the USAF actually ran rebadged RAF canberras for a number of years until they started delivering their own modified licensed versions
Click to expand...
 
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