Bill Gunston's conceptual stealth aircraft designs

[martinbayer]

Weaver,

I completely agree that engine and especially fan diameter is a major sticking point with respect to accommodation - that's why I said that the minimum achievable engine diameter for the required thrust would be a crucial question. In my understanding, at least some form of thrust augmentation like plenum chamber burning would certainly be required for the front nozzle(s) to increase thrust density for a constrained fan size, and the jet exhaust residue indicated in the drawings behind all four nozzles supports the notion that they are indeed all featuring combustion.

Martin

[Weaver]

Weaver,

I completely agree that engine and especially fan diameter is a major sticking point with respect to accommodation - that's why I said that the minimum achievable engine diameter for the required thrust would be a crucial question. In my understanding, at least some form of thrust augmentation like plenum chamber burning would certainly be required for the front nozzle(s) to increase thrust density for a constrained fan size, and the jet exhaust residue indicated in the drawings behind all four nozzles supports the notion that they are indeed all featuring combustion.

Martin

Hmmm - matter of artistic interpretation: I'd say the front nozzles (and the front of the rear nozzles), certainly in the side view, show distinctly less discolouration than the rear ones. You can find pictures of Harriers with dirty front nozzles, clean rear nozzles and any combination thereof: it seems to depend on what the surrounding fuselage is painted with and how recently the aircraft was cleaned, as much as anything. Remember that the air from the front nozzles of a Harrier is still at around 100 deg C, which is perfectly capable of "browning" an inferior paint, given enough time.

BG's design was presented in the context of a discussion of stealth, in other parts of which the author was highly dismissive of fast, SR-71ish designs due to the high IR signature of their exhausts. If his V/STOL design really does have PCB, then it's IR stealth would be that much more compromised, since the offending nozzles are not only on the lower surface of the aircraft, clearly visible from the ground, but must also heat up a considerable area of fuselage skin around them.

[martinbayer]

I agree it's largely a matter of conjecture at this point, and there is a definite danger of overinterpreting a highly notional illustration and attributing patterns and features that don't really exist. Keep in mind though that in a RIVET installation the nozzles at the rear of the aircraft would actually be the front nozzles of the engine... 

Martin

[Sauragnmon]

Well... I would consider, that if the design was aimed at stealth, and there was the PCB to amplify the engine thrust, the designers could have taken this into account when they built it, and similar to the YF-23, incorporated heat-soaking tiles around the parts of the fuselage that would be taking the brunt of the exhaust, which would help reduce the IR Signature and prevent the harmful heating of the fuselage.

[martinbayer]

Actually, it would be reasonable to postulate that the PCB would only be engaged during VTOL operations, just like afterburners are only used to temporarily increase thrust during certain flight phases and maneuvers, and would be shut down during cruise flight, thus helping to minimize the IR signature during critical mission phases.

Martin

[GTX]

Getting back to the initiating post - modelling BG's concept.  I wasa thinking parts of an F-15, Concorde (for the wings potentially) and Harrier II would be used.  Thoughts?

Regards,

Greg

[Weaver]

Getting back to the initiating post - modelling BG's concept.  I wasa thinking parts of an F-15, Concorde (for the wings potentially) and Harrier II would be used.  Thoughts?

Regards,

Greg

Think you're right about the Concorde wings: they'll need Harrier outriggers, of course. Not sure how the scaleorama works out though.The smallest Concorde kit I'm aware of is 1/144th and it's still pretty long: the final model would almost certainly have to be 1/48th, and maybe 1/32nd.

I think the canopy is more F-16 than F-15. The rest of the fuselage is pretty much a spindle-shape (reminds me of a squid, for some reason).

Of course, the discussion about it's viability leads to the question: do you model it as illustrated or adjust it's proportions to make it more credible?

[GTX]

I think the canopy is more F-16 than F-15.

Doh!!!  Typo - meant to say F-16.  In fact, one could also use the F-16's inlet as the starting point for the intake.

Regards,

Greg

[Hobbes]

Think you're right about the Concorde wings: they'll need Harrier outriggers, of course. Not sure how the scaleorama works out though.The smallest Concorde kit I'm aware of is 1/144th and it's still pretty long:

there's a kit of the Tu-144 in a 1:360 from Academy...

[Weaver]

Another observation about the picture: the radome is right in front of the canopy sill, so there's no actual room for the radar itself (it would be on the pilot's lap). Solutions? Well you could scale the whole thing up (advisable for other reasons) in order to separate the radome from a proportionally reduced canopy, or you could make the nose solid, i.e. not a radome at all. In other writing, BG decried the idea of taking the Soviets on air-to-air in WWIII, advocating instead a much denser SAM belt and counter-air operations against their infrastructure, so it's unlikely he would see his stealth design as having an air-to-air role, and therefore needing a radar.

One thing most commentators got wrong in the pre-F117 speculation days was that they completely ignored the importance of detail in stealth design. You look at an F-117 and every unsealed panel has zig-zag front and back edges, every external feature is suppressed or shielded. BG's design (and, in all fairness, many others) has, by contrast, uniformly rectangular panels, exposed gun muzzles, exposed engine nozzles etc...

[Weaver]

I think the canopy is more F-16 than F-15.

Doh!!!  Typo - meant to say F-16.  In fact, one could also use the F-16's inlet as the starting point for the intake.

Regards,

Greg

Don't think so: offer the two up against each other and there's almost no point of comparison. The F-16 intake is a perfectly conventional intake that just happens to be on the belly instead of the side of it's aircraft. The BG intake is effectively a modified flush NACA intake.

[GTX]

I think the canopy is more F-16 than F-15.

Doh!!!  Typo - meant to say F-16.  In fact, one could also use the F-16's inlet as the starting point for the intake.

Regards,

Greg

Don't think so: offer the two up against each other and there's almost no point of comparison. The F-16 intake is a perfectly conventional intake that just happens to be on the belly instead of the side of it's aircraft. The BG intake is effectively a modified flush NACA intake.

Please re-read what I said:  could also use the F-16's inlet as the starting point for the intake - I was looking at it from a modelling pov:  i.e. what do I use to bash together into something that looks like this drawing!

Re the engine discussion, BG simply refers to the engines as being RB.199 sized that pull out sideways.

Regards,

Greg

[Weaver]

Greg - I understood what you meant, but my contention is that if you start with an F-16 intake and take away all the bits that don't fit the BG design, you end up with nothing left. Put it another way: if you start modifying the F-16 intake the match the BG, then by the time you've got it looking something like, you'll have expended more effort than it would have taken to scratchbuild it.

Actually, since you'd have to scratchbuild the fuselage anyway, it wouldn't be that hard to scratch the intake: the lip is just an extension of the rear fuselage skin, cut off on a curved line. You then sculpt a taper onto the back of a F-16ish nose and cockpit section and slide it in. The tricky bit would be making the internal contours, but then that's always the case.

[GTX]

Fair enough.  I suppose I was looking at it from the pov of how to get the most out of a kit.  I was thinking one could take the fuselage of an F-16 (which you want for the cockpit/canopy), turn it upside down, cut and reshape where necessary, use lots of putty and card, add on bits from Harrier etc...

Regards,

Greg

[Weaver]

I see what you're getting at, but the trouble is that an F-16 forward fuselage isn't a body of rotation: it has a flattened underside and a "chine" that leads into the wing root, so if you rotated it 180 deg, it wouldn't mate up with the centre fuselage without an awful lot more work.

One way to get a 1/72nd F-16 canopy without wasting a whole kit is to get the Revell two-seater: it has the all the single-seater bits still in it, including the canopy. Don't know about 1/48th though.