F-35 avionics system

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moon_light

New Member
So i recently saw this new blog about aircraft equipment
https://basicsaboutaerodynamicsandavionics.wordpress.com/ , the blog seem like a great collection of information and the author has managed to make it an enjoyable read without any of the fanboy or nationalistic stuff so i decided to share it here

About radar
https://basicsaboutaerodynamicsandavionics.wordpress.com/2016/04/12/radar-electronic-countermeasure/
https://basicsaboutaerodynamicsandavionics.wordpress.com/2016/08/11/radar-fundamentals-part-ii/

About ECM
https://basicsaboutaerodynamicsandavionics.wordpress.com/2016/03/29/electronic-countermeasure-ecm/

About stealth
https://basicsaboutaerodynamicsandavionics.wordpress.com/2016/03/04/stealth-techniques-and-benefits/

About ESM and geolocation
https://basicsaboutaerodynamicsandavionics.wordpress.com/2016/03/02/rwresm-and-passive-geolocation/
 
John Fedup

John Fedup

The Bunker Group
moon_light said:
So i recently saw this new blog about aircraft equipment
https://basicsaboutaerodynamicsandavionics.wordpress.com/ , the blog seem like a great collection of information and the author has managed to make it an enjoyable read without any of the fanboy or nationalistic stuff so i decided to share it here

About radar
https://basicsaboutaerodynamicsandavionics.wordpress.com/2016/04/12/radar-electronic-countermeasure/
https://basicsaboutaerodynamicsandavionics.wordpress.com/2016/08/11/radar-fundamentals-part-ii/

About ECM
https://basicsaboutaerodynamicsandavionics.wordpress.com/2016/03/29/electronic-countermeasure-ecm/

About stealth
https://basicsaboutaerodynamicsandavionics.wordpress.com/2016/03/04/stealth-techniques-and-benefits/

About ESM and geolocation
https://basicsaboutaerodynamicsandavionics.wordpress.com/2016/03/02/rwresm-and-passive-geolocation/
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Western airforces must be cursing the day the Internet came into being. Sure seems like a lot of free technical information is available. I guess spies already found this stuff long before it got posted on websites.:confused:
 
M

moon_light

New Member
  • Thread Starter Thread Starter
  • #3
John Fedup said:
Western airforces must be cursing the day the Internet came into being. Sure seems like a lot of free technical information is available. I guess spies already found this stuff long before it got posted on websites.:confused:
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Personally , i dont think spies care about these information , these knowledge may seem complex to us but to them it probably like the basics 1+1=2
 
John Fedup

John Fedup

The Bunker Group
moon_light said:
Personally , i dont think spies care about these information , these knowledge may seem complex to us but to them it probably like the basics 1+1=2
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IIRC, a scientific paper by a Russian scientist was the basis for conceiving the F-117. Basic scientific knowledge is important and so is the talent to apply it.
 
ngatimozart

ngatimozart

Super Moderator
Staff member
Verified Defense Pro
moon_light said:
Didn't the German have a stealth bomber even before that? Ho229 or sth?
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The Germans had the Horten brothers Ho229 which I believe flew some test flights, but never operationally. There is one aircraft in existence in the US and held by the USAF. If the war had lasted another year, the Ho229 had the potential to have devastated the allied bomber fleets. I believe that it had reasonably good low observable capabilities, but I am unsure whether or not anything official has made it into the public arena.
 
S

swerve

Super Moderator
John Fedup said:
IIRC, a scientific paper by a Russian scientist was the basis for conceiving the F-117. Basic scientific knowledge is important and so is the talent to apply it.
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IIRC Gerhard Löbert, the head of the German Lampyridae 1980s stealth project, said after it was made public, & someone questioned whether it was really independent of US work, given that it had adopted faceting like the F-117 that "Maxwell's equations have been public for over 100 years".
 
R

r3mu511

New Member
swerve said:
IIRC Gerhard Löbert, the head of the German Lampyridae 1980s stealth project, said after it was made public, & someone questioned whether it was really independent of US work, given that it had adopted faceting like the F-117 that "Maxwell's equations have been public for over 100 years".
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^maybe the question they should've asked instead was whether it was independent of Ufimtsev's work, hehe :D
 
S

swerve

Super Moderator
It would be interesting to know if the Lampyridae team knew of Ufimtsev's work.

Ufimtsev showed a way to calculate RCS before building a model. That method wasn't useful until computers could be thrown at it, which is why the USSR wasn't interested in it to start with. It was a step, which built on earlier work by people in other countries (e.g. the UK & Germany), as others later built on it. Low RCS aircraft could be designed & built without his work, but given his papers & significant computing power, it was much easier.

Good stuff, & useful for more than designing low RCS aircraft, but not absolutely essential.
 
gf0012-aust

gf0012-aust

Grumpy Old Man
Staff member
Verified Defense Pro
I've snapshotted the history of all the major players and timelines in the stealth primer elsewhere.....
 
gf0012-aust

gf0012-aust

Grumpy Old Man
Staff member
Verified Defense Pro
John Fedup said:
Western airforces must be cursing the day the Internet came into being. Sure seems like a lot of free technical information is available. I guess spies already found this stuff long before it got posted on websites.:confused:
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the east germans were regarded as probably the greatest tech harvesters of all time - and yet a fat lot of good it did them as they reached the tipping point where the knowledge they were securing was beyond their capacity to utilise even when handed on to the soviets

after the downfall of the wall it was apparent that they struggled and never were in a position to maximise what they had gathered.
 
R

r3mu511

New Member
swerve said:
Ufimtsev showed a way to calculate RCS before building a model.
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Fwiw, the technical content of Ufimtsev's paper (link to paper was in my first post above) is actually at a much lower level, as it was focused on a method of computation for the electric and magnetic fields produced by wave diffraction on simple geometric shapes (triangular wedge, disk, cylinder, cone, and other rotated paraboloids).

What he provided was a numerically computable approximation for the diffracted EM field strengths for these simple shapes which, though not as rigorous as those produced by the mathematical theory of diffraction, did not have as large a variation/error in values (when compared to experimental results) as those produced from the diffraction theory based on geometrical optics (he presents both in his paper as well).

Ufimtsev achieved the better results compared to geometrical optics because his work included focus on the currents induced on the surface of those simple shapes near the discontinuities/edges of the surface (what he termed as "non-uniform induced currents", as opposed to the "uniform induced currents", ie. current away from the edges, which was the focus of the geometrical optic approach).

As for the Germans, Ufimtsev does prominently cite Karl Schwarzschild several times in his paper as one of the early innovators in using the same computational method (what he terms the "physical theory of diffraction") in the computation of the wave diffraction of a slit. So this should make the German Lampyridae team happy as Ufimtsev credits a German physicist as an innovator of this computational approach, lol.

---

After that, it was then up to Denys Overholser (the mathematician at Lockheed) to actually take Ufimtsev's computation approximation method for triangular wedges and marry that with decompositioning a body into an aggregate of such simple shapes, computing the field strengths for each shape, and via the principle of superposition summing up the individual fields to give a resultant EM diffracted field value which when compared to the incident EM field strength would allow him to compute the RCS of the body he was studying.

swerve said:
Low RCS aircraft could be designed & built without his work
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In Rebecca Grant's book "B-2 Spirit of Innovation", that's exactly what she described about how Northrop went about in designing their XST aircraft (ie. the competition that led up to the F-117).

Since they didn't use Ufimtsev's paper and didn't have an equivalent to Overholser's "Echo-1" software being used at Lockheed, they instead relied on their historical experience in experimental testing/evaluation of RCS of actual USAF aircraft, with their XST design work progressing by bulding models and using actual range testing to validate their design.
 
S

swerve

Super Moderator
OK, so Ufimtsev provided a base on which a good method of predicting RCS could be built.

I've read that Northrop had its own software for predicting RCS, which predated the translation of Ufimtsev's main paper & was therefore written without reference to it, & gave a much looser approximation, therefore needing much more application of the old methods of models & range testing.
 
R

r3mu511

New Member
swerve said:
I've read that Northrop had its own software for predicting RCS, which predated the translation of Ufimtsev's main paper
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Do you happen to have any more info on this? Maybe the name of the person who worked on this software for Northrop? I'ld really like to read up on more papers which were used in the past by other manufacturers similar to the 1970's relationship of Lockheed to Overholser/Ufimstev's work.

gf0012-aust said:
http://www.defencetalk.com/forums/air-force-aviation/brief-history-lo-10856/
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Yup thanks, I read that article of yours right after I joined the forum. I'll admit though my tech interest is less on LO as a whole, and more on just RF scattering.
 
S

swerve

Super Moderator
r3mu511 said:
Do you happen to have any more info on this? Maybe the name of the person who worked on this software for Northrop? I'ld really like to read up on more papers which were used in the past by other manufacturers similar to the 1970's relationship of Lockheed to Overholser/Ufimstev's work.
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I'll have a look for it, & see if I can find the place I read about it again. IIRC it named the software, but I don't recall any mention of whose work it was.
 
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