A picture released for public consumption which may or may not resemble a real project. A prime example would be some of the old Loral ads. Showing a table full of black boxes isn't nearly "sexy" enough for your average marketer so they had a picture of a stealth fighter in their ads that looked like what they thought stealth looked like back in those days. To this day that damn thing pops up with people saying "what aircraft was this?"pometablava said:LowObservable, could you please tell me what is a PR image?
Read what I wrote. I said it's fictional.doggedman said:has no basis in any actual program that I'm aware of
On the contrary, it embodies everything the public thought stealth would look like in those days: upper surface inlets, smooth curvy edges, inward canted tails, canards (because they looked futuristic so all future fighter drawings had them pretty much), and 2D exhaust.doggedman said:Indeed, looking at the design, except for the canted verticals and top mounted intake, it bears little homage to low observable aircraft design.
I see Hejja died suddenly about three months ago.doggedman said:The artwork you are showing was done by an artist named Atilla Hejja.
You seem to keep missing the forrest for the trees. I didn't say it WAS representative of a stealth aircraft, I said it was representative of what the public THOUGHT a stealth aircraft would look like.doggedman said:Atilla died of a heart attack. I became friends with him through another artist I know, John Batchelor. Atilla was one of the best aerospace artists I've ever met. You might be interested to know that he and John also designed the V-44, a 4 engine version of the V-22 that appeared in Popular Mechanics some time ago. I understand that Boeing and Textron have looked at the configuration and even had a CGI movie of the V-44 at the Farnborough air show in 2006.
I think a great deal of public information was and is available regarding Low Observable aircraft design. Two references that comes to mind are Skolnik's book as well as Pyotr Ufimtsev's work on ray tracing. None of these works reference canards, inward canted tails, or smooth curvey edges as a the essentials for an LO design.
The planform of an LO penetrator (a fighter, reconnaissance, or bomber aircraft that penetrates hostile, defended airspace) generally employs a straight leading edge for the fuselage, wings, and empennage. Straight, and if possible parallel, edges allow you to focus and reflect incoming energy in specific directions (spikes). The configurations of the Have Blue, F-117, B-2, A-12, YF-23, F-22, X-32, F-35, and Boeing's Bird of Prey all retain the same straight, parallel edge configuration to some degree. Attilla's fuselage and wing design employs a continuous compound curve which results in an omni-directional scattering source; anathema to LO design. The canted verticals also employ compound curves which would themselves be large scattering sources. As a separate note, radar absorbing materials are employed to attenuate or reduce the signature.
Whereas the planform employs straight edges, expanding the planform to accommodate volume does employ continuous compound curves in order to scatter incoming energy away from the source of emission. Looking at the B-2 nose on gives a clear illustration of this as the fuselage blending into the wing is a continuous compound curve.
Some aircraft, such as the Lockheed/Boeing Tier 3- Dark Star had nearly straight wings and a semicircular fuselage. This creates a nose-aft spike which is desired for surveillance aircraft as they fly parallel to threat radars vs. penetrating.
Canards have little, if anything to do with LO design. Neither does smooth curvey edges or inward canted verticals. Indeed both the F-117 and YF-23 had outwardly canted verticals. To the best of my knowledge only the Have Blue demonstrators had inwardly canted verticals and I believe Lockheed really regretted doing that. In fact LO design would want you to eliminate as many control surfaces as possible (fore, aft, or vertical). You are correct about the inlets, however, as the top mounted inlets allow you to obscure the engine front face and avoid the scintillation effect caused by the rotating machinery. One final point, LO aircraft designers for the most part are electrical engineers and Physicists who care primarily about electrical emissivity not aerodynamics.