USAAF philopshy of the heavies being able to defend themselfs

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Never flown over Europe have you. If you had you would realise that 50% cloud cover is probably about the best you can expect for large parts of the year. Even if there was a good fat anti cyclone parked over the target when you factor in industrial haze and smog 50% cloud cover is something bomb aimers would dream about.
 

Evidently you don't know a lot about using navigation devices like this or in later times devices like an NDB or even a Localizer. In the earlier case the sound was used in lieu of needle or indicator (or in the case of a VOR or Localizer a CDI). The radio wave is a "finite" course or heading and the amount of "crab" would be the difference between the known beam direction and the actual course of the aircraft (the direction the nose of the aircraft is pointing or what is read off the compass or DG) True course vs. true heading - navigation 101. The same principal is used today and yes, crews used this technique when tracking or navigating with LF devices of the day.

I don't know what you're trying to say about air density - the last time I took physics I don't remember anything about air density effecting LF radio waves in at least this application.
 
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Siegfried said:
Inaccuries would come from low altitude cross winds and errors in the timming circuits; in oboe these even attempted to compensate for the effect of air density or the speed of radio waves but nothing is perfect, especially over long distances.
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How do you change the speed of radio waves , as far as I know that is the speed of light,
 

1. B-17's and B-24's were bombing targets in small packets intermittedly, employing tactics designed to avoid or minimize interception. They did not simply fly in on the notion that they need not worry about fighters. It is still an Apples and Oranges comparison to the mass strategic bombing raids employed over Germany.

2. The self defending concept was not selective in it's application. It was a theory cultivated by the bomber cliche that defensive fighters were an obsolete concept. You are using specific attributes of that theory to promote the idea that the concept was in fact successful or as you put it "partially" successful dependant on Whom was being bombed. That is a selective and hindsight ridden argument. The SDB concept was universal and indepedant of target nationality. Use of higher altitudes did not eclipse the primary argument that the bombers would be able to ward off swarms of enemy fighters. Japan was more than capable of intercepting planes at 22-24K. The B-29's flew far above that to specifically avoid fighters but ran into problems with bombing accuracy. To say it would work against Japan or Italy under the same circumstances as it was introduced over Japan in late 1944 using B-29's is an argument that cannot be proven anymore than saying if Germany had only had 10 more armored divisions they'd have beaten the Russians. Events don't occur in a Vacuum. A dedicated effort from the get-go of WWII against Japan, or even Italy would have resulted in a response from those countries to the threat.

3. I fail to see how Japan's airforce being worn down mainly by attrition in Theaters outside of Japan and involving a plethera of mission profiles equates to Japan 'sucking' at shooting down bombers over Japan.

4. LeMay didn't send in the bombers during daylight at low altitude because it would have been cost prohibitive. A B-29 loss was not applicable to a B-17 or B-24 loss due to the expense involved. A single B-29 cost $605,000 per plane. That is nearly 3x that of a B-17. General Hap Arnold noted this difference enough to be quoted as saying that B-29 losses could not be viewed in the same vein as earlier 4E types, but rather that each loss should be equated to the loss of a naval vessel...thus the loss of even a few bombers was something to be avoided at all costs. This included ultra high altitudes for day bombing and night missions at lower altitudes. LeMay....gambling on Japan's night defenses not being as well developed as Germany's ordered the removal of guns in order to maximize payloads per trip as the effort to put so many 29's in the air was a huge problem due to servicability issues, one of the main reasons why LeMay was put in charge. Many of his methods went against the grain of conventional wisdom but he got results.

B-29 missions over Japan in my view are not so much an example of Self Defending bombers but rather the progenitors to the threat avoidance mission profiles of later day bomber tactics due to their complexity and cost which makes even small losses cost prohibitive.
 

Sure you can calculate cross wind via the aircraft compass heading and the heading of the beam in consideration of A/C speed, just a bit of trignometry. After carrying out this calculation you can't do anything with it without getting on to a radio telephone to tell the x-gerate opperators on the ground to shift the beam or the Oboe stations to shift the flight path. Both the x-gerate beam and Oboe did not allow the pilots to offset the flight path AFAIKT.

Oboe III did allow free form approaches to target and its possible the path could be controlled from the aircraft rather than from the base station, also GEE-H since the interrogator was on the aircraft instead of the base station.
 
as MIflyer illuded to in his post way back.... the b10 was able to out run and fly higher than the fighter ac of the day....the p26 peashooter...so i guess they figured a b17 would fair the same or better against fighter pursuit. perhaps they also looked at the limited fuel capacity of fighter ac and decided that they bombers would only be in harms way for a short period and they would be able to deal with that. this whole argument was one of Chennault fought for in his early days...but of course "contemporary wisdom" won out and the "bomber will always get there" for lunch bunch prevailed. but not for too long as lessons learned in the skies over europe did prove they may get through but you may also lose a large number of them doing so.
 
pbfoot said:
How do you change the speed of radio waves , as far as I know that is the speed of light,
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The speed of light varies inversly in proportion to the refractive index of a substance, moreover the refractive index varies with the frequency under consideration. High density optical glass will slow light down to 2/3rds its speed depending on frequency. It's why you can change the path of light with a lens or prisim.

Radio wave velocity is also varies with the density of materials it propagates through.

The speed of light is constant but only in a vacuum. Oboe was effected by air density and altititude and was adjusted accordingly.
 
Completely, and utterly, wrong. Oboe's course accuracy had a spread of 35 yards (3 feet more than the wingspan of a Lancaster.) Read the memoirs of Professor R.V. Jones, who states that Oboe was the most accurate radio bomb-aiming system of the war, with an error radius of 120 yards (which is dozens, not hundreds.)
Oboe did not "ride a beam," which is why the Germans took so long to figure it out. The boffins worked out, by triangulation, the position of the target, and the distance of that target from the "Cat" transmitter. The pilot was briefed to fly a curving flightpath (called "Boomerang" by the Germans) at the precise distance from Cat. The transmitter sent a signal to the Mosquito, which amplified it, and sent it back, enabling the operator to work out its precise position with regard to the required flightpath.
The transmitter then continued to send the signal, consisting of either a stream of dots (at 133 per second,) if the Mosquito was too close, or a stream of dashes if too far away; they even allowed for sideways trajectories of the bombs, as they were being released on a curving flightpath, so the Mosquito was briefed to fly inside the line of the target, not directly over it. Knowing the height and speed of the Mosquito, the second transmitter (known as "Mouse") was able to signal (with fives dots and a dash) when the bombs should be released.
In December 1942, the British set up a test, and (contrary to usual procedure) warned the Belgian resistance that they were attacking the headquarters of Sector 7, in the Novitiate near Florennes. A small force of Mosquitoes was sent, and, within 48 hours, at great risk to themselves, the Belgians had reported back the yardage distances of the bomb falls; one had actually hit the building, which is surely a testament for Oboe's accuracy (if you read the right books, of course.)
Another example of Oboe's proficiency was during "Operation Manna," when aircraft dropped food containers within 100 yards (30 metres) of drop points (not zones) designated by the Dutch resistance.
 
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Again re-read what I wrote!!! - this has nothing to do with shifting beams. The beam is set to a given desired heading! When you start drifting you make small heading corrections to get the "center" tone. Eventually thru trial and error you can "crab," adjusting your "COURSE" to compensate for the wind drift which will be the difference between the course of the tone and the heading the aircraft is flying. This is the same principle when flying an NDB, the difference here is with an NDB is you have a needle pointing at the "beam." Read the above post as well!
 
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Siegfried said:
Oboe was effected by air density and altititude and was adjusted accordingly.
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Only at the greatest distances. "Radio Probagation" due to humidity affectes LF radio waves the most at greater distances. If adjustments were made due to air density proagation, they were done so for specific applications. As frequencies were increased in later navigation equipment, propagation was not even a considertion to the crew of the aircraft.
 

I have Jones's book, though not on me at the momment but its clear that Jones is allowing his use of lay language to make his point sloppy.

Oboe didn't have an "accuracy" of 35 yards it had a "resolution" of 35 yards. Accuracy is something else. The pilot of the Oboe equiped aircraft received a morse code dot-dash or dash-dot to tell him if he were too far to the left or right (+/-17 yards) of the centerline of the circular bomb run. The centerline of the beam could be further out depending on range.

For instance if the timming circuits of Oboe were 0.05% accurate then they would induce an 100m error at 200km range and a 200m error at 400km range. On top of that the further out you go from the cat and mouse stations the higher you have to fly which adds in further errors from the longer bomb fall.

Edgar Brooks said:
Completely, and utterly, wrong.
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Hah.



In both these cases Oboe was opperating at relatively close range which means less ranging errors and less bomb drift. In addition multiple bombs were dropped. It stands to reason one or two would get close. Yes Oboe could be accrurate but I stand by my point that it was far more inaccurate than the exaggerated triumphalism that the affable RV Jones put in his book. Engineers, Project managers and Sales folks are just as prone to exaggerate the accomplishments of their pet projects a WW2 pilots tended to overclaim.

Brown in his history of WW2 radar states Oboe as achieving a real world accuracy of around 220m. (from memmory) When you consider that Bomber command was then dropping bombs on markers dropped by Oboe it stands to reason that a Lancaster dropping of flares using an Mk.XIV optical bombsight is not going to be any more accurate than a B-17 dropping directly using an optical bomb sight.

The Germans were aware of the technique used by Oboe. Their EG-ON II system worked in exactly the same way using two Freya radar IFF transponders to do the same job as cat an mouse. The main difference was that the commands were passed on to the pilot manualy via voice rather than automatically embedded as morse code into the interrogation pulse.d

It did have advantages as it worked of prepared cards and so could fly an arbitrary non circular approach. As to why it took so long to discover Oboe, that is another story.
 

OK it could be I'm not getting something, I am an electrical engineer not a pilot so I have some preconceptions.

So if I can do a little thought experiment to nut things out with you.
1 Immagine a Mosquito doing 350mph with a 50mph cross wind flying at 20,000ft (6000m).
2 The angle of the crab relative to the designated essentially linerar flight path will be inverse-tangent(50/250) which is 8.13 degrees).
3 the aircraft crew only have the following information a/ TAS, b/ ground speed, c/altitude, d/ angle of the crab relative to the designated flight path.
4 from the above information they can work out the cross wind (which is 50mph) from 350 x tan(8.13)
5 A bomb released at 20,000ft will take 36 seconds to hit the ground, in fact more like 45 seconds due to terminal velocity.
6 During this 45 second fall a 50mph (22 meters a second) cross wind could push a bomb of course 45 x 22 = 1000m. Of course the bomb will not accelerate to 22m/s immediatly.
AFAIKT a 250kg bomb with a frontal Area of 0.25sqm and a Cd of 0.2 will create a drag of 224 Newtons at 50 mph. From F=ma this should create an acceleration of 1m/s.
So roughly the bomb could be pushed of around 200 by cross wind. I'd have to use a spreadsheet.

The only way I can see that being compensated is to ofset the flight path about 100m.

Oboe crew 'may' have been able to do this if the aircraft transponder incorporated a small adjustable delay (say 1 microsecond = to about 150m) that was ofset by the timming circuits in the cat interrogator and computer on the ground. Once having the cross wind the crew could adjust the transponder delay slightly to shift the path of the aircraft to the left or right.

Calulating head wind is a no brainer but cross wind is harder.

Surely there must be an English Boffin with a working Oboe set that could tell us!
 
The problem with all of the major combatents attitudes towards bombers is that their stratagy and tactics had not evolved in consideration of radar.

Without radar a raid is discovered only around the time the raid crosses the border, there is little warning. It take a lot of time to assemble all of the reported information. Basically the raid is only intercepted after it has penetrated fairly deeply into the defenders territory. Finally when it is intercepted it will be only by a small number of aircraft as the defenders fighters have not had time to assemble and of neccesity are dispersed.

In this situation the "bomber will always get through" is probably right.

The development of radar completely changed everything. Large well organised fighter waves could be vectored onto the bombers even before they crossed into the defenders territory.

Even if a bomber is as effective at shooting down a fighter as the fighter is the bomber it is a loosing proposition as the bomber costs 4 times as much as the fighter.

In this situation a 270mph bomber opperating against 370mph fighters guarantees interception.

However a bomber penetrating at fast cruise of 330mph will likely evade interception.
 
Siegfried said:
I have Jones's book, though not on me at the momment but its clear that Jones is allowing his use of lay language to make his point sloppy..
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Only to someone trying desperately to "prove" how poor British technology was. I, too, have the book, and am intrigued by your "sloppy" jibe, since everyone else that I know, who has also read it, has said how understandable and non-technical the book is.
Will you ever get into your head, THERE WAS NO BEAM; the Cat transmitter sent a signal, the Mosquito amplified it and returned it, and Cat calculated, from the time delay, the aircraft's relative position to the desired flight line, and, thereby, the "accuracy" of its relative position; I won't get into accuracy vesus resolution, since that's pure semantics, and designed to fog the issue. There was no "dot-dash," or "dash-dot" signal either (proof, if ever it was needed, that you don't read, properly, others' entries); there was a stream of dots, or a stream of dashes. How, exactly, in 133 pulses per second, could a radio operator tell if the sequence was -. or .-?
Do you have proof of the existence of these "errors," in the so-called "trimming circuits" (which were back at the transmitter, not in the aircraft) or are you, yet again, using guesswork as "proof?" You are also ignoring the point that it was the Mouse station that calculated the bomb release point, using information on the local conditions sent back from the crew; the aircrew didn't use a bombsight, since it was redundant.
Hah.
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Silly. Sneering signifies a loss of the argument.
In both these cases Oboe was opperating at relatively close range which means less ranging errors and less bomb drift.
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No, it doesn't; bomb drift is caused by the ambient weather conditions, not distance from these shores. Since every target was worked out by the triangulation method, distance made no difference, either, since the position of the target was fixed accurately, and the flightpath worked out from that.
In addition multiple bombs were dropped. It stands to reason one or two would get close.
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Not if your figure of hundreds of yards error is true. So your claim, now, is that, 35 years after the end of the war, and having retired, Jones exaggerated the stories for some mythical gain, which only seems to germinate in your fertile imagination.
Or, to put it another way, Lancaster bombsights could be the equal of B-17's bombsights, even at night. And the RAF weren't just dropping bombs on the Oboe markers; they had a Master Bomber, who would direct them onto the best aiming points, and how much "aim-off" to allow, if the markers were inaccurate. Never heard of Brown, but I note that your assertion of "hundreds of yards" error is now down to 250 (7 times the wingspan of a Lancaster,) which is not quite so dramatic.
No, it didn't; the Freya transmitters used the old system of beams, while (I repeat, ad nauseam) OBOE DID NOT USE BEAMS.
It did have advantages as it worked of prepared cards and so could fly an arbitrary non circular approach. As to why it took so long to discover Oboe, that is another story
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No, it isn't; without any beams to latch onto, the Germans couldn't figure it out, for months.
 
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Yards or feet?

250 feet would be approximately twice the wingspan of a Lancaster, 250 yards would be 6 times.
 

You're over engineering a simple process. That's why sometimes engineers make crappy pilots!!!!

Read on how to navigate with an ADF and how NDB instrument approaches are completed, then read Edgar Brooks post below on how the system was actually used.
 
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BC also used low level visual marking by pathfinders (Lancs and Mossies), used sky marking flares when the cloud cover was too thick for ground marking and bombed individually.

The Master bomber would also remark the target if the TI was losing visibility. Also, more than one marker would be used for the target.

Only a handful of an 8th AF bomber formation carried the Norden bomb sight. The Norden required a long straight run up to the target, so as soon as there was opposition from the Luftwaffe and flak units the procedure of individually bombing a target was no longer desirable. So the 8th AF bombed in formation, to maintain their defensive box formations on the run in to the target.
 
Wusak - true the 8th (and 15th) bomber on the lead crews. Having said that, each squadron of 9-12 B-17/24 had a lead bombadier sighting on a specific target. It was'nt as if the Bomb group toggled on one a/c.

With a decent formation in a staggered box, win tip to wing tip spread was ~2000 feet/666 yards from high to low groups on a maximum effort Group (~50) formation

Another thing to consider when you are watching old film of formations going to target. Usually a Maximum of two Bomb Groups would be tasked for a specific Aiming Point. If so, they would be in trail rather than eschelon so the wing tip to wing tip horizontal spread would be the same over the target.

As you know a multi Task Force effort of say 750 B-17s and B-24s in April 1944 might be tasked to strike 15 separate targets in 7-10 general areas.

Normally, for Europe one target might be CAVU and another obscured by clouds. For the latter, the Wing CO had the authority to re-direct to another (pre-determined) target, thence to a Target of Opprotunity if secondary was also obscured.

The reason the Scouts were formed in summer of 1944 was to send a small force of Mustangs all the way to the target and report conditions, then fly to alternate and perform same recon - all the time communicating with their assigned task Force CO.
 
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