The advent of Stealth aircraft

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Visionist
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The advent of Stealth aircraft

Post by Visionist » 07 Jul 2007 13:29

This is more of a question than a WI, but does anybody know what , if any, ideas were circulating around WW2 as regards aircraft invisible or low observable to Radar?

Back then, to make a stealth plane required construction from wood. The British Mosquito was made from plywood, decreasing weight and tapping the skills of British woodworkers.

Today, we often hear of the "Legendary Mosquito", about it's massive speed, superior handling, elite flightcrews, highly accurate bombings etc.

But I have heard nobody state it was hard to detect. Was this possible advantage not known when it was designed?

The Germans had several flying wing projects, notably the Horten XVIII, whose proposed wooden construction would have given it a high lift/thrust to drag/weight ratio, giving it superior range, speed and altitude performance.

Perfect for dropping something deadly on Manhattan then.


But did the engineers realise such an aircraft would be nigh on invisible to US defence Radars, or was this an ulterior, unknown benefit of a wooden construction?

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Post by TexasRanger » 07 Jul 2007 14:22

The Germans historically were capable of tracking the Mosquito on radar. You can get a pretty big radar return off of an airplane's engines, which cannot be made of wood. The Mosquito's wooden construction was a result of a desire to save resources.

The Horten XVIII apparently had steel tubes in its fuselage, so I don't know how stealthy that would be...

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Post by Tim Smith » 07 Jul 2007 14:36

I suspect that metal airscrews (propellors) are great at reflecting radar energy as well. So I doubt if any prop plane can be as stealthy as a jet.

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Post by Visionist » 07 Jul 2007 14:56

Tim Smith wrote:I suspect that metal airscrews (propellors) are great at reflecting radar energy as well. So I doubt if any prop plane can be as stealthy as a jet.


One problem facing jet aircraft is that a radar can "see" the entire, relatively large fanblade area, which is why stealth designs bury the engines deep within the fuselage and feature very fine mesh intakes, the openings smaller than a radar wavelength.

A wooden construction may have been useful for maintenance, since aircraft like the B2 Spirit spend 90% of their time grounded, undergoing cosmetic skin smoothing.

With a wooden plane, you can just sand it smooth, but you have to repaint the whole thing...



Was it possible (at least for the US, maybe not Germany) for the manufacture of ferrous paint, containing millions of microscopic iron balls, which absorb the Radar signals (used on the SR71 I believe), to have occured during the war?

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Post by phylo_roadking » 07 Jul 2007 18:22

Okay, first off the SR71 Blackbird is NOT a "Stealth" aircraft - the paint does absorb a SMALL percentage of radar beamed at it, but not very much. The surface coating is heat resistant because the the SR71's main defence from SAMs at the time of design in the late 60's-early '70s was its speed and altitude, allowing it to escape the Soviet surface-to-air missiles that brough down Garu Powers by outrunning them.

But I have heard nobody state it was hard to detect.
...in other words, it was EASY to detect! :-)

DeHavilland were quite far down the pecking order for aircraft-grade dural and aluminium when they were driving the Mosquito porject. What they DID have was a decades of expertise in building twin-engined racing aircraft among others, using traditional materials. The Mosquito was actually as technically advanced at the Spitfire - its fuselage was a stressed monocoque - just made of shaped and bonded plywood rather than aluminium!

The very large tailplane and Mossie's wide wingspan were its undoing when it came to being painted on radar. But again its main defence was its speed, the Mosquito could out run most Axis fighters throughout the war in a straight line.

(remember, its NOT just "unobtanium" paint coatings absorbing radar that make a plane "stealthy", thats just icing on the cake. What REALLY does it is designing an aircraft who's silhouette generates very few retruns....either by VERY limited cross section - very few upright surfaces on a flying wing! - or in the case of the F117 Stealth Fighter, by combining the barest possible control surfaces in canted, non-upright profile with "faceting" of fuselage surfaces to break up large flat areas. This legendarily makes it impossible to fly without computer assistance, as its general non-aerodynamic profile requires constant changing of pitch and trim.)

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Post by HistorianSr » 10 Jul 2007 18:56

If you read about the Jack Northrop flying wings, you will find they were difficult to detect on radar. The similarity between the B-2 Stealth Bomber and the Gotha Go-229 (or Horten Ho-IX) is difficult to ignore.



HSr

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Post by maltesefalcon » 10 Jul 2007 23:36

Stealth aircraft were only useful once precision gudied weapon systems were available; complete with night vision targeting.

This would enable fairly small raids to accomplish what took thousands of sorties previously.

Stealth or not, it would be hard to miss the signature of a 1000 plane raid.

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Post by Visionist » 10 Jul 2007 23:57

maltesefalcon wrote:Stealth aircraft were only useful once precision gudied weapon systems were available; complete with night vision targeting.

This would enable fairly small raids to accomplish what took thousands of sorties previously.


Indeed, and the Germans had developed both precision weapons and low light tv to a proficient degree by war's end.

Imagine a Horten stealth bomber dropping a guided nuke on Fort Knox?!

Stretching things, certainly, but imagine it?...

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Post by JonS » 11 Jul 2007 00:26

The Tupolev Bear is notoriously easy to spot because of it's propellors, not because of it's size.

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Post by TexasRanger » 11 Jul 2007 12:37

HistorianSr wrote:If you read about the Jack Northrop flying wings, you will find they were difficult to detect on radar. The similarity between the B-2 Stealth Bomber and the Gotha Go-229 (or Horten Ho-IX) is difficult to ignore.



HSr


You can see the engine intakes from the front of the Horton Ho-IX, at least from the pictures I can pull up from the internet. This means you'll get a nice big radar return.

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Post by TexasRanger » 11 Jul 2007 12:52

Visionist wrote:
maltesefalcon wrote:Stealth aircraft were only useful once precision gudied weapon systems were available; complete with night vision targeting.

This would enable fairly small raids to accomplish what took thousands of sorties previously.


Indeed, and the Germans had developed both precision weapons and low light tv to a proficient degree by war's end.

Imagine a Horten stealth bomber dropping a guided nuke on Fort Knox?!

Stretching things, certainly, but imagine it?...


Stretching things quite a bit -- it looks like Fat Man was higher than the projected payload of the Amerika bomber, and Little Boy sits right on the limit. Neither was a 'guided' bomb. (We've also had a previous discussion on the German nuclear program.) While both the Western Allies and the Germans developed guided bombs to a certain degree (AZON, Fritz-X), I do not believe guided weapons became really widespread until the Vietnam war. (The famous example is Thanh Hoa Bridge, which was attacked with 'dumb' munitions repeatedly (800 sorties) with little success, then twice with F-4 phantoms armed with laser guided bombs, successfully.)

Fort Knox is also in Kentucky, which is a little ways in from the coast.

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Post by Visionist » 11 Jul 2007 13:36

TexasRanger wrote:
Visionist wrote:
maltesefalcon wrote:Stealth aircraft were only useful once precision gudied weapon systems were available; complete with night vision targeting.

This would enable fairly small raids to accomplish what took thousands of sorties previously.


Indeed, and the Germans had developed both precision weapons and low light tv to a proficient degree by war's end.

Imagine a Horten stealth bomber dropping a guided nuke on Fort Knox?!

Stretching things, certainly, but imagine it?...


Stretching things quite a bit -- it looks like Fat Man was higher than the projected payload of the Amerika bomber, and Little Boy sits right on the limit. Neither was a 'guided' bomb. (We've also had a previous discussion on the German nuclear program.) While both the Western Allies and the Germans developed guided bombs to a certain degree (AZON, Fritz-X), I do not believe guided weapons became really widespread until the Vietnam war. (The famous example is Thanh Hoa Bridge, which was attacked with 'dumb' munitions repeatedly (800 sorties) with little success, then twice with F-4 phantoms armed with laser guided bombs, successfully.)

Fort Knox is also in Kentucky, which is a little ways in from the coast.


This is going off topic, but what WOULD have been the effects of the US losing all the gold in Fort Knox (and I believe the original copy of the Constitution was stored there) during the war, as well as the considerable surrounding military garrison?

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Post by phylo_roadking » 11 Jul 2007 15:03

You can see the engine intakes from the front of the Horton Ho-IX, at least from the pictures I can pull up from the internet. This means you'll get a nice big radar return.


It wasn't Northrop's jet powered flying wing that showed up its negligible radar image - it was his earlier prop-driven test models with air intakes just being oblongs on the wing leading edge.

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Post by LWD » 11 Jul 2007 15:58

Visionist wrote:....
This is going off topic, but what WOULD have been the effects of the US losing all the gold in Fort Knox (and I believe the original copy of the Constitution was stored there) during the war, as well as the considerable surrounding military garrison?

The loss of the gold would hardly be a big deal in WWII it might afterwards. However the gold would hardly be lost unless it was actually in the fire ball. The chance of even a stealth bomber making it that far and hitting the target are so close to zero that no one can tell the difference. Note if the weather is good people will see the bomber and Knox is several hundred miles from the coast. Plenty of time to scramble fighters. Then of course they have to find Knox. I suspect even finding Kentucky would be non trivial for the LW at this point in time.

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Post by TexasRanger » 11 Jul 2007 16:46

phylo_roadking wrote:
You can see the engine intakes from the front of the Horton Ho-IX, at least from the pictures I can pull up from the internet. This means you'll get a nice big radar return.


It wasn't Northrop's jet powered flying wing that showed up its negligible radar image - it was his earlier prop-driven test models with air intakes just being oblongs on the wing leading edge.


I have read that the YB-49 supposedly disappeared from radar 'at certain angles', but I have not heard anything similar regarding the prop aircraft.

Also note that the YB-49 was reportedly not particularly stable, and the Northrop flying wing bombers were reportedly worse bomb platforms than comparable conventional designs.

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