An airburst, however, would not have the same effect even with a yield of several hundred kt’s. Remember that blast effect does not scale up with yield. Its been years since I read up on this but, from memory, it requires something like an eight-fold increase in yield to double blast effect.

Can be calculated as:

r = (Yield/2.5kt)^0.33
The radius is then for 4.6psi overpressure (at optimum explosion height).

Just to get an idea what ~5psi overpressure means, Little Boy had a yield of 15kt, so its 5psi radius was about 1.8km.
Now, if we increase to 120kt, the 5psi radius becomes 3.6km, or an increase of 100% for an eightfold yield increase.
That explains the quest for megaton nuclear weapons in the 50ies and 60ies, where assumed accuracy was small and only few warheads made it at all. Considering the demonstrated accuracy of bombers in WW2, a Little Boy nuclear weapon might miss enough to fail to destruct a target (like a factory area).

Thermal effects have roughly the same characteristics, while radiation increases even less with yield.

EL/L-8222 – Comprehansive Self Protection Pod

I like the more and more dot.com-oriented naming strategy. Everything is “joint”, “advanced” or in this case “comprehensive”. When does the Apple iJam make its debut, where you can jam the opposing SAM site and discuss the event in a Web 2.0 enabled blog on the net in real time.

That is true, however we do know that damage that would cause the immediate destruction of a P-51 or Spitfire was regularly shrugged off by the Jug’s. I have the great fortune of being close friends with Hub Zemke Jr. and had the pleasure of speaking with his father before he passed away. In his opinion(and I think his opinion certainly matters more than mine) the P&W 2800 that they used was responsible for bringing many pilots back who otherwise would have been lost. There are very few recorded fighters flying home and then being scrapped because they are too damaged for repair. Of those very few the majority are radial engined.

Cheers
Gary

I don’t want to make a point versus the old man’s experience, but you’ve made a statement versus a turbo-prop versus a radial engine. A turbo-prop doesn’t have water cooling, so it may be equally survivable … or not.

The stories from WW2 are sometimes misleading, as the losses are normally not exactly tracked by cause. Dead pilots cannot tell a story. And other influence factors may sometimes mask the conclusion.

I take it you are talking about the Wright R-3350 Duplex-Cyclone? I’m not in a position to judge the combat damage resistance of a turoprop but from what I hear the radial would probably be the better choice. I know of cases were FW-190s and various other radial engined WWII fighters returned to base shot to pieces with bullets and shrapnel embedded in the engine, split cylinders, bleeding oil etc. That has to count as five star reliability.

The problem with that statement is that you don’t know how many aircraft crashed due to engine damage. If the history tells us of 20 occasions where P-47 returned to base with severely damaged engines, there may be another 100 lost aircraft due to engine damage. Nobody researched the reason for lost aircraft, not in war, when the aircraft crashes somewhere. That is what you call “silent evidence”.
And how would a turbo-prop score, which in the end weights considerably less per produced hp and you could use that saved weight for additional armor.

Materials: please no one claim that any weight can be saved using composites. The nature of its operational environment would make composite aircraft completely unsuitable. Weight savings are secondary issue.

LO is what the F-35 is, the F-22/B-2A sits on the border between LO & VLO.
VLO is a tail-less design like the X-47B, i.e. that exhibits ‘broadband stealth’ characteristics.
Taken to it’s extreme, VLO would embody replacement of reflective internal metallic structural spars to defy LW radars in the 2GHz regime.

If anything, Sweetman lends tentative support for the F-35- citing the limitations of X-47B-type automation and the necessity for the man-in-the-loop F-35- but VLO- it aint.

Also the time frame must be taken into account. For 1991 the F-117 was “very low obeservable”, as it wasn’t actually observed. Today, the F-117 cannot penetrate an airspace any more.
When the F-35 enters service, air defenses will develop counter-stealth tactics. And there are quite a few options.

The most crucial point has been missed.. Is he right?, so far all we have had is personal attacks…

Is the basic concept he proposes correct? that there are three main sorts of stealth, and that LO & VLO stealth has some drawbacks.

I think what he has written has merit, I have always found Mr Sweetman to be very insightful and very good at crafting technical subjects in easy and humourous manner. (perhaps he needs more smilies in his piece for the benefit of others here:D).

Why is it that stealth is perceived by some as more effective than jamming?

Its the difference between looking for something transparent vs having sand thrown in your eyes, either way you can’t see the target.

I don’t think Mr Sweetman is biased against the F-35 but he does show his experience in the industry when he takes what LM or the USAF say with a large pinch of salt due to the string of broken promises that have come before.

That’s not bias that’s experience. so there’s never any need to compare Mr Sweetman or anyone to Carlo Kopp… not even Carlo…:diablo:

Cheers

He is right, but he doesn’t really say anything new.
He just says, that air power will be important in the future, that stealth is important and that sensors will increase in importance.
He does not hail a single concept.
Every open-minded school boy knows that stealth in aircraft like the F-22 and F-35 has some limitations. And one can expect more effective sensors to proliferate, partly outsmarting the stealth aircraft.

The point he makes about UAVs & UCAVs is correct, too. Here again, anything stating anything essentially different just doesn’t understand the limitations of automation.

The linked presentation is a good read.
Some points he makes are essential, and often not understood.

What’s the spooling down time of a RR Pegasus – and how does it effect the crew escape time of the Harrier while in the hover stage of flight?

I’m presuming of course, that the spooling down time of a tubofan increases in parallel with the increase in the By-pass ratio…?

I’m not sure about the last comment. Turbofans have probably more inertia, but at the same time the fan does actual physical work, so is slowed down.
When looking at large bypass turbofans at airports, you recognize that engines slow down considerable within a time frame of one minute.
Anyways, the N1/N2 speed over time after fuel cut off would look like a 1/x function: huge speed loss in the beginning, and a longer time with some residual shaft rotation.

1/x: http://www.matheplanet.com/matheplanet/nuke/html/uploads/6/7723_1_3.jpg