# Norden Bombsight



## billrunnels (Dec 17, 2017)

Here is a copy of a flyer we used following WWII when appearing on a panel etc

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## airminded88 (Dec 17, 2017)

billrunnels said:


> Here is a copy of a flyer we used following WWII when appearing on a panel etc
> View attachment 476179



Amazing peace of memorabilia Bill.
Were those flyers made in the 90's?
I see the "50th Anniversary of WWII" stamped on them.


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## billrunnels (Dec 18, 2017)

airminded88 said:


> Amazing peace of memorabilia Bill.
> Were those flyers made in the 90's?
> I see the "50th Anniversary of WWII" stamped on them.



They were published in 1995 by the Minnesota Chapter of the 8th Air Force Historical Society which was founded in 1983. I served on the original Board of Directors.

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## airminded88 (Dec 18, 2017)

billrunnels said:


> They were published in 1995 by the Minnesota Chapter of the 8th Air Force Historical Society which was founded in 1983. I served on the original Board of Directors.



Pretty nice.
What are you personal thoughts about the Norden Bill?


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## stona (Dec 18, 2017)

The Norden sight was a superb instrument, there were other sights that could match it in the real world of operational bombing, but not theoretically. It and it's associated systems were however very, very complicated.

It was difficult to manufacture to the standard required (which is why many, later, sub-contracted sights were not capable of the accuracy of the original Norden built sights). In December 1943 Wright Field tested 200 M-9 Norden bomb sights, manufactured by Norden, Remington Rand, Borroughs, Lukas-Harold and Victor, finding them _"...to be inferior to those sights which were being produced about two years ago"_.
The first 600 sights produced by Victor were recalled, but Norden got the blame for providing _"incomplete, inaccurate and obsolete" _engineering data.

Colonel R.E. Jarman, technical executive of the Armament Laboratory at Wright Field expressed his frustration with the Norden Company when he wrote
_"...if I ever enter the Norden factory again and deal with their high executive personnel, it will be too soon."_

Something else, often overlooked, is just how difficult the sight was to maintain. The training of personnel to look after and maintain the sights once in service was something of a debacle, particularly for the Army.

Cheers

Steve

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## billrunnels (Dec 18, 2017)

airminded88 said:


> Pretty nice.
> What are you personal thoughts about the Norden Bill?


I
They were just as good as the people who used them. It took a good pilot to hold a steady altitude and indicated air speed of 150 mph and a good bombardier who did the correct calculations for the bombsight and could control flight on the bomb run.

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## airminded88 (Dec 19, 2017)

stona said:


> The Norden sight was a superb instrument, there were other sights that could match it in the real world of operational bombing, but not theoretically. It and it's associated systems were however very, very complicated.
> 
> It was difficult to manufacture to the standard required (which is why many, later, sub-contracted sights were not capable of the accuracy of the original Norden built sights). In December 1943 Wright Field tested 200 M-9 Norden bomb sights, manufactured by Norden, Remington Rand, Borroughs, Lukas-Harold and Victor, finding them _"...to be inferior to those sights which were being produced about two years ago"_.
> The first 600 sights produced by Victor were recalled, but Norden got the blame for providing _"incomplete, inaccurate and obsolete" _engineering data.
> ...



Excellent information Steve. Many thanks.

Cheers


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## airminded88 (Dec 19, 2017)

billrunnels said:


> I
> They were just as good as the people who used them. It took a good pilot to hold a steady altitude and indicated air speed of 150 mph and a good bombardier who did the correct calculations for the bombsight and could control flight on the bomb run.



Couldn't agree more with you there Bill.
After bombs away, what was the type of maneuvering that bombers took to get away from the target area?
Over the years I have come to the perception that after hoping slightly, lightened by the departure of the bombload, the bombers would enter a tight turn to left and proceed to pierce their way out of enemy airspace.

Cheers


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## billrunnels (Dec 19, 2017)

airminded88 said:


> Couldn't agree more with you there Bill.
> After bombs away, what was the type of maneuvering that bombers took to get away from the target area?
> Over the years I have come to the perception that after hoping slightly, lightened by the departure of the bombload, the bombers would enter a tight turn to left and proceed to pierce their way out of enemy airspace.
> 
> Cheers


After bombs away the pilot took over control and made a gradual formation turn right or left to clear the flak area. The turn began while the bomb bay doors were closing.

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## Hansie Bloeckmann (Dec 21, 2017)

Was is a true story about hair from a famous actress (Rita Hayworth maybe) being used for the crosshairs in this instrument?


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## stona (Dec 21, 2017)

Hansie Bloeckmann said:


> Was is a true story about hair from a famous actress (Rita Hayworth maybe) being used for the crosshairs in this instrument?



I've never heard that story.
Given the number of sights produced I rather doubt it. Also the thickness of the material was a factor in accuracy and had to be constant. The cross hair width could give a 10' error for an M-33 bomb dropped from 25,000' 
Cheers
Steve

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## billrunnels (Dec 21, 2017)

Hansie Bloeckmann said:


> Was is a true story about hair from a famous actress (Rita Hayworth maybe) being used for the crosshairs in this instrument?


I have no idea. It would make for a good publicity stunt and probably sharpen the sighting


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## Tim Moore (Dec 21, 2017)

That story has been pretty well debunked. The most popular version is that a lady named Mary Babnik Brown had blonde hair that had never been treated with chemicals or a curling iron, and was the only hair suitable for the crosshairs. In fact, that story was so pervasive that President Reagan sent her a thank-you letter on her 80th birthday. There is even an entire Wikipedia page on her and the myth. The other tale told is that black widow spider web was used. All of this is complete bunk. Try and imagine one woman’s hair supplying 90,000 Norden bombsights. The only grain of truth is that there was some interest by the War Department in using women’s hair in devices. 
I have restored dozens of Norden bombsights and can tell you that the crosshairs are etched on a glass lens. When I get home I will post a picture.

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## Gunsights (Dec 21, 2017)

Hi everyone,
I have this oddly modified Norden stabilizer
and was wondering if anyone here might
shed some light on it’s application?
As you see It has this large interface located between the stabilizer and Glide Bombing Attachment. I’ve never seen this before.
Any suggestions??
Thanks!


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## Tim Moore (Dec 21, 2017)

Here are some pictures of the crosshairs etched on a lens. Not hair. It is amazing that there is an entire Wikipedia web page with a bibliography and references about something so obviously false: Mary Babnik Brown - Wikipedia

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## Tim Moore (Dec 21, 2017)

Gunsights said:


> View attachment 476577
> Hi everyone,
> I have this oddly modified Norden stabilizer
> and was windering if the anyone here might
> ...


Really don't know, and can't find any reference pictures with that segment.

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## Tim Moore (Dec 21, 2017)

And another thing. That same Wikipedia article on Mary Brown talks about the bombsight being surrounded by “booby-trapped charges”. Sheesh.

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## pbehn (Dec 21, 2017)

Not an expert on hairs, or cross hairs but if you used human hair they would overlap, and if you were looking for the finest or straightest hair you would use hair from a blonde or ginger child ( I used to have one) and in any case many other animals have finer hair, away from hair I would think spiders webs were approaching the thinnest......amazing how stories grow legs and run, the wonder of the "net" doesn't stop these legends it actually makes them accepted "facts".

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## Tim Moore (Dec 21, 2017)

Guess I could learn how to do Wikipedia. Wouldn’t want to step on anyone else’s hard work but that article on Mary Brown is pure fantasy. Why can’t the truth suffice? That’s just one reason I love Bill’s posts. He was there and can tell us first hand, how it really was. Nobody that was referenced in that Wikipedia article was there or had even seen a Norden bombsight.


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## Gnomey (Dec 23, 2017)

Good stuff Bill!


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## MIflyer (Jan 9, 2018)

Here are some shots of a Norden Bombsight. A friend of a friend of mine bought one back in 2013.

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## billrunnels (Jan 9, 2018)

MIflyer said:


> Here are some shots of a Norden Bombsight. A friend of a friend of mine bought one back in 2013.


great shots of the bombsight head.


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## Hansie Bloeckmann (Jan 9, 2018)

If it cost $10K to produce the Norden in 1940, how were they distributed in a squadron of B-17's. Did each aircraft carry a Norden, or did the USAAF equip just the lead aircraft with a Norden, figuring that the rest of the squadron would drop their bomb load in a "follow-the-leader" scenario?


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## billrunnels (Jan 9, 2018)

Hansie Bloeckmann said:


> If it cost $10K to produce the Norden in 1940, how were they distributed in a squadron of B-17's. Did each aircraft carry a Norden, or did the USAAF equip just the lead aircraft with a Norden, figuring that the rest of the squadron would drop their bomb load in a "follow-the-leader" scenario?


In the beginning each B-17 had a Norden, in fact all of the aircraft our crew used on missions in 1945 still had one. However later in the war(1944- ?) they started dropping on the lead and many aircraft did not have a bombsight. In addition to the war zone aircraft, each Bombardier School AT-11 had one as well as classrooms.

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## MIflyer (Jan 9, 2018)

The Nordens were taken out of the Doolittle Raid B-25's and replaced with a simple protractor and gunsight type of device made out of bent aluminum. At the altitudes they were flying the Norden was of no use. 

My high school math and mechanical drawing teacher was a bomb/nav on the Doolittle mission from the USS Hornet. After the war he reproduced a copy of the bombsight for a museum.

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## daveT (Feb 7, 2018)

I believe that many Norton Bomb sights are still around. Many Air Museums have one and many are in private collections. I have read that they were compromised early in the war and the Germans had copies of them. The Germans used medium bombing and had no use for them. There really was no need for such procedures to ensure they were kept secret.


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## wuzak (Feb 8, 2018)

MIflyer said:


> The Nordens were taken out of the Doolittle Raid B-25's and replaced with a simple protractor and gunsight type of device made out of bent aluminum. At the altitudes they were flying the Norden was of no use.
> 
> My high school math and mechanical drawing teacher was a bomb/nav on the Doolittle mission from the USS Hornet. After the war he reproduced a copy of the bombsight for a museum.



I thought that the Nordens were reserved for the heavy bombers.

Maybe that was later in the war?


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## wuzak (Feb 8, 2018)

billrunnels said:


> In the beginning each B-17 had a Norden, in fact all of the aircraft our crew used on missions in 1945 still had one. However later in the war(1944- ?) they started dropping on the lead and many aircraft did not have a bombsight. In addition to the war zone aircraft, each Bombardier School AT-11 had one as well as classrooms.



I believe dropping on the lead began in 1942 or 1943, after initial raids gave the 8th AF enough experience to change their methods.

In any case, a formation would still need several aircraft with the bomb sight, in case the lead bombers were shot down.

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## stona (Feb 8, 2018)

wuzak said:


> I thought that the Nordens were reserved for the heavy bombers.



Initially they were reserved for the Navy (the Mk XV). It was only in July 1931, as an indirect result of federal regulations on open bidding for military procurement, that the Army Air Corps was even aware that such a sight existed.
As war approached the USN had spent twenty years figuring out three methods for sinking ships (dive bombing, level bombing and torpedo bombing)and wasn't about to give up on any of them. This caused the Navy to hold on to thousands of Norden sights when the Air Corps had a critical need for them. 
They say Americans don't get irony, but the irony of the USN failing to use the Norden sight, developed by it at great expense, in WW2 must be obvious, though maybe not to the Army, which did use the sight, but had to subordinate its needs for the device to those of the Navy for more than a decade.
It's quite a story, and sometimes it makes you wonder whether the two services were serving the same country!
Cheers
Steve

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## MIflyer (Feb 8, 2018)

One thing I wonder about is the role of Bombardiers and navigators and where they intersected. With the B-25 they had a bomb/nav, one man that did both jobs from his position in the nose. With the Martin B-26 in Europe they had both a bombardier and a navigator, with separate positions, although soon after takeoff it seems that the Nav went down to the nose and argued with the Bombardier over where they were, since both were trained both as navigators and bombardiers. Heavy bombers like the B-17 and B-24 seemed to have separate people in those positions, too. 

By the way the Martin B-26 had the Norden bombsight, but in order for the bombardier to use the nose gun the bombsight had to be removed. I read of one mission where they were told to bomb an enemy troop concentration and then go down and strafe. The bombardier sighted through the Norden, dropped the bombs, and then as they turned around to strafe, removed the Norden and handed it to the Navigator, who held the bombsight while the Bombardier gleefully went to work with the .50 cal nose gun and the pilot strafed with the 4 package guns.

So how did they decide when they had a Bomb/Nav or separate positions?


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## Elmas (Feb 8, 2018)

That Norden could not do miracles is exemplified by this photo, taken from a bomber attacking Cagliari, 28th Feb. 1943.
Target was the harbour, that is clearly seen in the upper right part of the pic.
These bombs are going to miss of more than one mile, exploding in the open sea at the left.
Clear sky, less than a dozen fighters of the 51° Stormo to harass the bombers, very low AA activity.


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## Tim Moore (Feb 8, 2018)

How do you know they are going to miss? Look at the direction of several of the smoke columns in the picture. The Norden bombsight was designed to position the aircraft and release the bombs upwind of the target. Also, look at the lowest bombs in the picture, and you can see them being carried downwind towards the target.


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## Elmas (Feb 8, 2018)

Certainly the bombs nearest to the camera are going to miss. They are more or less on the vertical of the coast, the attack is vectored from NW to SE and the nearest land on that direction is Tunisia.
From the sun shadows on the bombs this was the second attack of the day, late afternoon.
Another attack on the same target, 31/3/1943.
Of course I didn't say that _all_ the bombs are going to miss.


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## billrunnels (Feb 8, 2018)

MIflyer said:


> One thing I wonder about is the role of Bombardiers and navigators and where they intersected. With the B-25 they had a bomb/nav, one man that did both jobs from his position in the nose. With the Martin B-26 in Europe they had both a bombardier and a navigator, with separate positions, although soon after takeoff it seems that the Nav went down to the nose and argued with the Bombardier over where they were, since both were trained both as navigators and bombardiers. Heavy bombers like the B-17 and B-24 seemed to have separate people in those positions, too.
> 
> By the way the Martin B-26 had the Norden bombsight, but in order for the bombardier to use the nose gun the bombsight had to be removed. I read of one mission where they were told to bomb an enemy troop concentration and then go down and strafe. The bombardier sighted through the Norden, dropped the bombs, and then as they turned around to strafe, removed the Norden and handed it to the Navigator, who held the bombsight while the Bombardier gleefully went to work with the .50 cal nose gun and the pilot strafed with the 4 package guns.
> 
> So how did they decide when they had a Bomb/Nav or separate positions?


I know nothing about B-26 procedures. On the B-17 the bombardier did the bombing and the navigator did the navigation. The navigator had no training on the bomb sight but could toggle the bombs in an emergency. The bombardier was certified in Pilot and DR navigation and could provide navigation assistance in an emergency. We worked as a team on missions.

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## Elmas (Feb 8, 2018)

Harbour of Cagliari, today.
It can be easy observed that the focal point of the release in the previous photo is the center of the main basin, and bombs are spread in a radius of more than one mile.
And this was, in my opinion, an extremely precise bombing, by WWII standards.
To the left there is the industrial harbour, not existing in WWII days.
Btw, I can imagine that my engineer Colleagues did design the Norden bombsigth to drop bombs upwind, and not downwind.... and in that photo the wind was very low, looking at the waves on the coast.


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## billrunnels (Feb 8, 2018)

Elmas said:


> View attachment 481772
> 
> Harbour of Cagliari, today.
> It can be easy observed that the focal point of the release in the previous photo is the center of the main basin, and bombs are spread in a radius of more than one mile.
> ...


A number of factors were considered when choosing the heading for the bomb run, flak concentration was one.

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## Elmas (Feb 8, 2018)

AA was mostly located in the two hills I've highlighted. But of course AA in Cagliari was not exactly equal to Essen.
When I was a lad (late '50) there were still one or two rusted cannons I use to play with in the upper one, as my Grandmother lived at the foot of the hill.


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## Tim Moore (Feb 8, 2018)

What I am stating is that you cannot make a determination based on a picture of a bomb after it has just been released as to where it will strike. You cannot know where the bomb will strike without knowing the trail value and the crosswind component and its resultant drift correction. The bomb will always land downwind of the point of release, the crosstrail distance. It will always travel forward of the point of release due to the velocity imparted to it by the plane. It will always land behind the airplane at the time of impact, the trail distance, due to forward and upward wind resistance. You cannot state based on a picture of bombs just released whether all, some, or none will strike the target without knowing those values. I have attached a picture with a description of these functions. I have also restored and operated dozens of Norden bombsights over the years and have attached a video with a visual demonstration of the solution of the bombing problem at the beginning.






_View: https://youtu.be/D8IxBv494jk_

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## Elmas (Feb 8, 2018)

I simply cannot understand how a bomb released from a plane wich is travelling at a f.l. of say 15000 ft and at 300 mph in the direction of the arrow could hit the target identified by the red circle. Those bombs will go undoubtely in the sea.
Surely my fault, laws of kinematics and dynamics of motion that I studied in the University years ago here in the old Europe are probably different than those that apply in U.S...


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## Tim Moore (Feb 8, 2018)

Carl Norden, born Dutch but who lived in Switzerland, was old Europe and he invented the Norden bombsight using those laws.

Perhaps this video clip could help you understand:


_View: https://youtu.be/CTPD3lzqYAI_


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## Greg Boeser (Feb 9, 2018)

MIflyer said:


> One thing I wonder about is the role of Bombardiers and navigators and where they intersected. With the B-25 they had a bomb/nav, one man that did both jobs from his position in the nose. With the Martin B-26 in Europe they had both a bombardier and a navigator, with separate positions, although soon after takeoff it seems that the Nav went down to the nose and argued with the Bombardier over where they were, since both were trained both as navigators and bombardiers. Heavy bombers like the B-17 and B-24 seemed to have separate people in those positions, too.
> 
> By the way the Martin B-26 had the Norden bombsight, but in order for the bombardier to use the nose gun the bombsight had to be removed. I read of one mission where they were told to bomb an enemy troop concentration and then go down and strafe. The bombardier sighted through the Norden, dropped the bombs, and then as they turned around to strafe, removed the Norden and handed it to the Navigator, who held the bombsight while the Bombardier gleefully went to work with the .50 cal nose gun and the pilot strafed with the 4 package guns.
> 
> So how did they decide when they had a Bomb/Nav or separate positions?


Crew on the B-26 and the B-25 varied throughout the war based on the mission needs. As originally designed, both carried a crew of five, however the first B-26 units to deploy used crews of seven - pilot, co-pilot, navigator, _enlisted_ bombardier, engineer, radioman and air gunner. B-25s carried a crew of six - pilot, co-pilot, navigator, bombardier, radioman, engineer/gunner. In the Pacific, a fully trained navigator was essential. The navigator's position was in a compartment directly behind the flight deck, so during flight it was common for the navigator to come forward and watch the action over the shoulders of the pilot and co-pilot. Once skip bombing was introduced, the bombardier was usually omitted from the crew to reduce manpower requirements, bombs being toggled by the co-pilot. However, even after most B-25s had been converted to strafer configuration, a few planes in each squadron retained the glazed nose for level bombing, each flight leader carrying a bombardier with bombsight, the others toggling on the lead ship's drop.
Mediums in North Africa and Europe generally carried a crew of six, combining the roles of bombardier and navigator in a single crewman, the "bombagator", though the lead planes usually carried a veteran lead bombardier and lead navigator. Low level ops proved too dangerous, so formation attacks at medium altitude became the standard procedure. Since precision group bombing placed more emphasis on concentration than individual accuracy, the "bombagator" or "togglier" toggled off their bombs when the lead ship dropped. The reason heavies retained fully trained bombardiers and navigators, while the function was combined in the mediums probably had to do with the greater demands placed on long range, high altitude operations compared to the shorter range missions at lower altitudes of the mediums. Regarding crew reductions, there were suggestions that mediums could dispense with co-pilots, since, it was said, their only real role was raising and lowering the landing gear. A block of B-26s, the B-26C-6, was produced without a co-pilot's position, but these were quickly retrofitted in the field by unit commanders.
Interestingly, the B-26 and B-25 were supplanted by the Douglas A-26, which had no co-pilot, the navigator assisting the pilot when necessary. Produced in glazed and solid nose configurations, it continued the practice of wingmen toggling on the lead ship's drop.

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## stona (Feb 10, 2018)

At least the bombardiers can see the target at Cagliari. The average circular error in such good conditions was around 900 feet, which is not bad, if not exactly precise.

The real problem came when the target was obscured. In the 456 days from January 1944 to March 1945 visual bombing with the Norden sight, by the 8th AF, was only possible on 132 days. Other methods, like timed runs, were far less successful. In late '44 the 97th Bomb Group attacked Pilsen Skoda after a forty mile timed run, and* missed by ten miles!
*
Senator Elbert Thomas (Utah), though he had religious and cultural reasons for his moral objections to strategic bombing, was not exaggerating by much when he said that precision bombing was "one of the outstanding hoaxes of military history".

Cheers

Steve

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## billrunnels (Feb 10, 2018)

stona said:


> At least the bombardiers can see the target at Cagliari. The average circular error in such good conditions was around 900 feet, which is not bad, if not exactly precise.
> 
> The real problem came when the target was obscured. In the 456 days from January 1944 to March 1945 visual bombing with the Norden sight, by the 8th AF, was only possible on 132 days. Other methods, like timed runs, were far less successful. In late '44 the 97th Bomb Group attacked Pilsen Skoda after a forty mile timed run, and* missed by ten miles!
> *
> ...


Depends on how you define "precision". In my book 900 feet from 25,000 feet is precise.

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## Tim Moore (Feb 10, 2018)

Daylight precision bombing has gotten a bad rap from a variety of angles. There are some points to be kept in mind:

1) It took several years to find out what targets were the most important strategically, especially oil refineries.

2) Results steadily improved during the war. General Lemay made two changes: He insisted on a straight run to the target without evasive action, and he chose the best bombardiers to be lead bombardiers, with the others in the group dropping on signal from the lead. The C-1 autopilot was introduced, allowing the bombardier to steer the plane much more accurately on the bomb run. The time over the target was increased. The types of bombs, particularly smaller ones, were changed, resulting in more accuracy. Finally, with air superiority won later in the war, it was possible to use lower bombing altitudes. What all this meant was that the Circular Error Probable (50% of bombs falling in a radius) went from 75 feet in prewar testing to around 1200 feet in 1943, but improved to 900 feet by 1945. When looking at how many bombs fell within 1000 feet of the target, this went from 10-15% in early 1943 to 40-60% in early 1945.

3) Defending against daylight precision bombing required an enormous amount of Germany/Luftwaffe resources, around the clock with the Americans by day and British by night.

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## stona (Feb 10, 2018)

_"Depends on how you define "precision". In my book 900 feet from 25,000 feet is precise."_

I would agree, but it wasn't as precise as had been achieved back in the US, and it wasn't precise enough to make all the calculations done for the number of bombs (and bombers) required to destroy a target to be correct.
For example, Research showed that the 500lb M-43 with 267 pound of TNT created a crater two feet deep and nine feet in diametre in sandy loam with an instantaneous fuse.
If the calculations of the Bombs and Fuzes Subsection were correct (in fact they were too optimistic) the eight M-43s typically carried by a B-17 would damage 32,000 square feet. The Eighth Air Forces average circular error of 900 feet was an area 79 times greater!
Richard Hughes, then head of Eighth Air Force's Operational Planning Section concluded:

"The pre-war myth of a bomb in a pickle barrel from 20,000 feet was quickly exploded, and, to the intense disappointment of the regulars, it became apparent quickly that to destroy, or even to hit, a given target was going to call for a vastly heavier weight of attack than had been dreamed of in pre-war doctrine. Contrary to all expectations, with a few notable exceptions, the strategic bombers of the 8th and the 15th Air Forces seldom succeeded in achieving real precision bombing."

This is not a criticism of the men doing the bombing. I think you all did a remarkable job in unimaginably difficult circumstance. It is a result of huge over optimism among some senior, but still relatively young, airmen who developed the US pre-war doctrine. The doctrine quite literally developed around an unproven technology in the Norden sight. Good as it was, it was impossible to achieve anything like the experimental results operationally. It's why you and your comrades flew so often, for so long and in such huge formations. The eventual cost of the combined bomber offensive to the US and UK in treasure, but more importantly blood, was far in excess of anything anticipated.

A more fundamental problem for the US planners was the weather. It didn't matter how good a sight was, if the target was obscured by cloud it was useless. An air force and its personnel, assembled and supplied at a vast cost, cannot simply sit on its behind for three days out of four because of bad weather. The result, in a worse case scenario, was missing by ten miles.

Cheers

Steve

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## Elmas (Feb 12, 2018)

_"Error": difference between the value which has been computed and the correct value._

Let’s assume a B17 that is going to do his final bombing run, as in the following picture. Please excuse the bad quality of the drawing, made in hurry.







Instruments say FL 25k, speed 220 kts.
FL: what is the error due to the instrument between the real value of FL and the indicated one?

Plus or minus 1%? 2%? 5%? 10%?

An error is certainly introduced into the sistem.

Speed. Again: 220 knt plus or minus 1%? 2%? 5%? 10%?

We are introducing another error.

And these are “readings from instruments”. Now will see the “educated guesses”.

Wind speed at FL and on the ground?

Direction of the wind at FL and on the ground? When Mistral is coming here in the Mediterranean you can have a gentle SE sea breeze on the ground but, looking at the clouds at 20k you can see them galloping in the sky from NW… Of course there could be some device to measure the drift, but again, what error in this device?

And now to things that are so aleatory that could not even be guessed.


How is the gradient of temperature and air density between GL and FL? The distribution will be linear as in B, increasing with the FL as in A or decreasing as in C?

For just this, different density of the air, a bomb can miss by _hundreds_ of _yards_, not _feet_.

And all this for a bomber wich is flying all alone in a perfect route to a perfectly visible target.

But bombers fly in formation so, if the Leader is in the center and perfectly straight to the target the planes to the left and to the right will miss of more than 300 yards.








If we now add, like salt and pepper, Me-109s and Flak, and as tomato sauce the weather conditions of NE, we can easily understand that the words of Senator Elbert Thomas (Utah) were pure truth.

Of course: better to have a Norden than a lesser device or not to have a device at all: but Norden was certainly not a panacea.

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## Hansie Bloeckmann (Feb 12, 2018)

billrunnels said:


> A number of factors were considered when choosing the heading for the bomb run, flak concentration was one.


Thanks, Bill. As a large number of Allied bombers were "taken out" by German Flak batteries, I can clearly see why the AA batteries locations, as well as wind and climate conditions, could influence the flight path, both to target, and also for the return leg. Hansie


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## Hansie Bloeckmann (Feb 12, 2018)

Elmas said:


> _"Error": difference between the value which has been computed and the correct value._
> 
> Let’s assume a B17 that is going to do his final bombing run, as in the following picture. Please excuse the bad quality of the drawing, made in hurry.
> 
> ...


Elmas, could you please repeat that quotation here? I, for one, would very much like to hear it.


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## Hansie Bloeckmann (Feb 12, 2018)

Tim Moore said:


> And another thing. That same Wikipedia article on Mary Brown talks about the bombsight being surrounded by “booby-trapped charges”. Sheesh.


Mr. Moore raised a good point in his post. What "self-destruct" mechanisms were part of the Norden Bombsight- If B-17 was hit and crash landed (with the crew hopefully all parachuted out safely) and the aircraft and its components recovered by the Luftwaffe, would they be able to duplicate the Norden. Somewhere I read that the first series had a "cup" designed for the muzzle of a 1911-A-1 .45, or other issue USAAF sidearm, so that the bombardier or other crew member could shoot into that orfice and seriously damage the lenses--that might well be an "old wives' tale", like the one about an actress donating hair for the cross hairs of the aiming lens. Can anyone clarify this?? Thanks-- Hansie..


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## Elmas (Feb 12, 2018)

Hansie Bloeckmann said:


> Elmas, could you please repeat that quotation here? I, for one, would very much like to hear it.



Post #42 above, posted by Steve (stona)
_"Senator Elbert Thomas (Utah), though he had religious and cultural reasons for his moral objections to strategic bombing, was not exaggerating by much when he said that precision bombing was "one of the outstanding hoaxes of military history"._


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## billrunnels (Feb 12, 2018)

Hansie Bloeckmann said:


> Thanks, Bill. As a large number of Allied bombers were "taken out" by German Flak batteries, I can clearly see why the AA batteries locations, as well as wind and climate conditions, could influence the flight path, both to target, and also for the return leg. Hansie


They did a great job in planning the route.


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## Tim Moore (Feb 12, 2018)

There was no self-destruct device in the Norden bombsight. The bombardier was to use his pistol and fire two shots into the rate end and one through the eyepiece. Pardini debunks this myth in his book, "The Legendary Norden Bombsight." There is mention in this book and in Hallion's book, "America's Pursuit of Precision Bombing, 1910-1945" of either a Mark 5 Mod 1 or Mark 15 Mod 1 destructive device designed by the Navy, but there are no records of it ever being installed or used. Likewise, there is mention of an 18" cylinder with 15 pounds of magnesium designed to be ignited and turned on the bombsight as a blowtorch, but this seem fantastical and no reports of this being used, either. (Imagine doing that while wearing an oxygen mask.) The confusion probably stems from the fact that there were thermite grenades on the bombers designed to destroy the entire _aircraft, _but nothing of this sort for the bombsight. Having restored dozens of Nordens, I have never seen any evidence of such a device.

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## Tim Moore (Feb 12, 2018)



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## stona (Feb 13, 2018)

The security measures were pointless as the Germans had details of the sight in 1938. 

I've said before, nobody in their right mind would try to copy one of the Nordens of the type(s) in question. They might be more interested in how it solved the various elements of the 'bombing problem' but would be sensible to develop their own sight. I don't know if the Norden influenced German sights, there are as many opinions as people you ask!

It is a remarkable instrument, the Norden, but the principles on which it is based were hardly unknown to other nations.

Cheers

Steve

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