Ranger instead of Ark Royal

[daveshoup2MD]

The difficulty of using bombs to sink battleships is well illustrated by the hits absorbed by Ise, Hyuga and Haruna in July 1945 from US carrier groups. Ise took at least 5x1000lb bomb hits (US fliers claimed 9x1000lb hits) plus numerous others. Those came from 4 carrier airgroups, each much larger than that of Ranger.

In 1948 the RN carried out dive bombing trials against Nelson while she was anchored in the Firth of Forth using 1000lb and 2000lb bombs. They had to reduce the bombing height from 8000ft to 6500ft after 39 straight misses! The conclusions reached were
1. All bombs had to be dropped from at least 5000ft to be effective
2. Dropped from 3000-4000ft in practice the bombs only penetrated 2.95-4.75 inches
3. It was not easy to hit a ship from those heights and certainly not from 5000ft
4. It was noted the target was stationary
5. Although not easy, Nelson’s armour was pierced, proving battleships were vulnerable to this kind of attack. ...

This reminds me of the US 9th Air Force trying to destroy bridges in 1943. My Fathers Bombardment Group came to the UK in the summer of 1943 thinking they could drop bridges with only a single squadron size attack group, from a safe altitude of 20,000+ feet. Eventually they were getting success from 15,000 & lower. They also jumped up the attack groups to 36 & 54 bombers. Sprinkling a few bombs from high (safe) altitudes did not get results.

In 1944 the Army Air Forces tried single engine planes making dive attacks on the bridges. The results sound something like those described above. The target had to be saturated from relatively low and vulnerable altitudes & nearly all the bomb strikes had superficial results. Aim enough bombs & eventually you get a critical hit somewhere & the targets collapses/sinks.

"Precision bombing from heavy bombers is very, very accurate -- the bombs always hit the ground."

[Richard Anderson]

This reminds me of the US 9th Air Force trying to destroy bridges in 1943. My Fathers Bombardment Group came to the UK in the summer of 1943 thinking they could drop bridges with only a single squadron size attack group, from a safe altitude of 20,000+ feet. Eventually they were getting success from 15,000 & lower. They also jumped up the attack groups to 36 & 54 bombers. Sprinkling a few bombs from high (safe) altitudes did not get results.

In 1944 the Army Air Forces tried single engine planes making dive attacks on the bridges. The results sound something like those described above. The target had to be saturated from relatively low and vulnerable altitudes & nearly all the bomb strikes had superficial results. Aim enough bombs & eventually you get a critical hit somewhere & the targets collapses/sinks.

I am afraid that is not really correct Carl. On 7 May 1944 the 365th Fighter Group attacked the Vernon and Mantes-Gassicourt bridges. At Vernon, eight P-47 dropped 16 1,000-lb bombs and cut the bridge in half. The larger Mantes bridge suffered heavy damage. Then, from 27 May to 6 June 1944, IX Fighter Command struck 13 bridges with a total of 1,181 sorties and 854 tons of ordnance. Twelve of the bridges were destroyed.

The main limitation was from Leigh-Mallory restricting bridge targets as being too difficult for fighter bombers and too likely to tip the Allied hand to the Germans. It wasn't until early May that the Loire bridges became targets and 24 May before all the Seine bridges went on the target list.

[paulrward]

Hello All :

Back in my college days, those of us who were majoring in what is now called STEM
( Science, Technology, Engineering, and Math ) noticed that the Liberal Arts Majors,
including the History Majors, seemed to be somewhat... shall we say... lacking...
in Math Skills. Most of them were required to take nothing more rigourous than
Basic Algebra, though a few of them had to take a class in Statistics and Probability.

In other words, while they understood basic arithmetic, anything over the number 10,
which used up all of their fingers, was pretty much a mystery to them.

Mr. Anderson Stated :

..........Then, from 27 May to 6 June 1944, IX Fighter Command struck
13 bridges with a total of 1,181 sorties and 854 tons of ordnance. Twelve of
the bridges were destroyed.......

OK, Lets do some basic Math. 1181 Sorties to destroy 12 bridges adds up to nearly
100 sorties per bridge. And 854 tons of bombs to do ditto, means that roughly
71 TONS of bombs were required to drop each bridge !

Considering that they were dropping 1000 lb bombs, that means that each bridge, on
average, required 142 bombs to knock it out.


Based on what happened in North Korea in the 50s, and North VietNam in the 60s-70s,
maybe Bridges were a lot harder to hit than some Historians think !


Respectfully :

Paul R. Ward

[Richard Anderson]

FFS

Results Achieved by Selected Attacks Against French Rail Bridges by Sections of Lines of Interdiction (Table 12 in Effectiveness of Air Attack Against Rail Transportation in the Battle of France, USAAF Air Evaluation Board in the European Theater of Operations, 1 June 1945)

First Line of Interdiction
Fighter Bombers - 11 cuts, 97 tons per cut
Medium Bombers - 32 cuts, 155 tons per cut
Heavy Bombers - 10 cuts, 330 tons per cut (includes 163 tons dropped without achieving a cut)

Second Line of Interdiction
Fighter Bombers - 5 cuts, 53 tons per cut
Medium Bombers - 5 cuts, 217 tons per cut
Heavy Bombers - 17 cuts, 185 tons per cut

All
Fighter Bombers - 11 cuts, 83 tons per cut
Medium Bombers - 37 cuts, 163 tons per cut
Heavy Bombers - 27 cuts, 239 tons per cut

All types - 60 cuts, 173 tons per cut

[Kingfish]

FFS

Results Achieved by Selected Attacks Against French Rail Bridges by Sections of Lines of Interdiction (Table 12 in Effectiveness of Air Attack Against Rail Transportation in the Battle of France, USAAF Air Evaluation Board in the European Theater of Operations, 1 June 1945)

First Line of Interdiction
Fighter Bombers - 11 cuts, 97 tons per cut
Medium Bombers - 32 cuts, 155 tons per cut
Heavy Bombers - 10 cuts, 330 tons per cut (includes 163 tons dropped without achieving a cut)

Second Line of Interdiction
Fighter Bombers - 5 cuts, 53 tons per cut
Medium Bombers - 5 cuts, 217 tons per cut
Heavy Bombers - 17 cuts, 185 tons per cut

All
Fighter Bombers - 11 cuts, 83 tons per cut
Medium Bombers - 37 cuts, 163 tons per cut
Heavy Bombers - 27 cuts, 239 tons per cut

All types - 60 cuts, 173 tons per cut

Just curious, what constitutes a "cut"?

The diameter of a bomb crater?

Would 2 or more overlapping diameters count as one cut?

[Richard Anderson]

Just curious, what constitutes a "cut"?

The diameter of a bomb crater?

Would 2 or more overlapping diameters count as one cut?

Cut as in the line was cut. If on a section of track a cut was just that, a place where the track was gone. It was found relatively easy to execute a cut by simply lining up along a length of straight track and dropping bombs - errors in range were then meaningless, while errors in deflection were normally small. The problem was single cuts, even from 1,000-lb bombs were relatively easy to repair. The solution there was death by a thousand cuts, nearly daily bombing to inflict many cuts, eventually isolating repair equipment from its supply sources.

In the case of a bridge, the bridge was gone, either a section of span or the entire bridge structure was collapsed.

One of the complications with bridges was that it was difficult to destroy the bridge piers, which often allowed a temporary span laid, but more often that was the case with a road bridge.

[Kingfish]

Cut as in the line was cut. If on a section of track a cut was just that, a place where the track was gone.

Let me rephrase the question: If a 500 lb bomb destroys a section of track, ergo a 'cut", then what would 6x 500lb bombs dropped in a tight, overlapping line constitute, a cut or 6 cuts?

[Richard Anderson]

Let me rephrase the question: If a 500 lb bomb destroys a section of track, ergo a 'cut", then what would 6x 500lb bombs dropped in a tight, overlapping line constitute, a cut or 6 cuts?

A cut. If it were six bomb cuts spread over 20 kilometers they might count it as six cuts, but in general a cut was caused by the attack of a squadron element on a single section of line. Line cuts were also only counted if they were of 24 hours duration or greater, so they were more of a moving figure than bridge cuts. For example, in the region Ouest on 10 June there were 35 line cuts, 48 on 30 June, 37 on 25 July, and 9 on 31 July.

Line cutting also involved the strafing of locomotives and trains. From 21 May to 5 June, it was estimated that 310 were damaged in region Ouest and 490 between 6 June and 31 August. That damaged added to the burden of the rail repair crews.

The last component were attacks on rail centers, especially marshaling yards and rail maintenance and repair facilities. In combination, it resulted in an average of 9.5 of the 13 main line routes closed in region Ouest during June and July, 5.3 to bridge cuts, 3.1 to track cuts, and 1.1 to rail center cuts.

[daveshoup2MD]

Let me rephrase the question: If a 500 lb bomb destroys a section of track, ergo a 'cut", then what would 6x 500lb bombs dropped in a tight, overlapping line constitute, a cut or 6 cuts?

A cut. If it were six bomb cuts spread over 20 kilometers they might count it as six cuts, but in general a cut was caused by the attack of a squadron element on a single section of line. Line cuts were also only counted if they were of 24 hours duration or greater, so they were more of a moving figure than bridge cuts. For example, in the region Ouest on 10 June there were 35 line cuts, 48 on 30 June, 37 on 25 July, and 9 on 31 July.

Line cutting also involved the strafing of locomotives and trains. From 21 May to 5 June, it was estimated that 310 were damaged in region Ouest and 490 between 6 June and 31 August. That damaged added to the burden of the rail repair crews.

The last component were attacks on rail centers, especially marshaling yards and rail maintenance and repair facilities. In combination, it resulted in an average of 9.5 of the 13 main line routes closed in region Ouest during June and July, 5.3 to bridge cuts, 3.1 to track cuts, and 1.1 to rail center cuts.

Thanks for the details above; interesting way to approach what we later (well, I think it was later) referred to as BDA...

[Carl Schwamberger]

This reminds me of the US 9th Air Force trying to destroy bridges in 1943. My Fathers Bombardment Group came to the UK in the summer of 1943 thinking they could drop bridges with only a single squadron size attack group, from a safe altitude of 20,000+ feet. Eventually they were getting success from 15,000 & lower. They also jumped up the attack groups to 36 & 54 bombers. Sprinkling a few bombs from high (safe) altitudes did not get results.

In 1944 the Army Air Forces tried single engine planes making dive attacks on the bridges. The results sound something like those described above. The target had to be saturated from relatively low and vulnerable altitudes & nearly all the bomb strikes had superficial results. Aim enough bombs & eventually you get a critical hit somewhere & the targets collapses/sinks.

I am afraid that is not really correct Carl. On 7 May 1944 the 365th Fighter Group attacked the Vernon and Mantes-Gassicourt bridges. At Vernon, eight P-47 dropped 16 1,000-lb bombs and cut the bridge in half. The larger Mantes bridge suffered heavy damage. Then, from 27 May to 6 June 1944, IX Fighter Command struck 13 bridges with a total of 1,181 sorties and 854 tons of ordnance. Twelve of the bridges were destroyed.

1181 sorties, then 98 per bridge destroyed, or 91 sorties per all 13 for a 93% success rate, if the Vernon and Mantes-Gassicourt bridges are included then 1197 sorties or 90 sorties. I don't have accurate information for total sorties vs bridges run by the medium bomber groups of the 9th Air Force. It looks like in the Spring of 1944 a 54 plane group of B26 were considered sufficient for a high probability of dropping the bridge. But, I also notice attack groups as small as 36 were used as well. Further obfuscating this were techniques developed of dividing the attack group into two, with the second following shortly behind the first. If the first salvo dropped the bridge the second would divert to a alternate target. That made it yet more difficult to estimate sorties per bridge attacked or destroyed or attacked. Less than 100 but more than 36? The difference between the 365th FG & my fathers 386th Medium Bomber Group would have been the number of bombs per sortie. Twice the 1000lbrs, and six to seven crew risked vs one pilot.

I've seen claims the SBD & SB2C diver bombers had better results but have never seen numbers.

The main limitation was from Leigh-Mallory restricting bridge targets as being too difficult for fighter bombers and too likely to tip the Allied hand to the Germans. It wasn't until early May that the Loire bridges became targets and 24 May before all the Seine bridges went on the target list.

Which target list? My fathers squadron the 555th was trying to bomb bridges in 1943. There appears to have been a hiatus on that & Marshaling yards became their favored transportation target for some time. The problem of actually hitting the bridge at a tension or bearing point got some attention over the autumn and winter, but its not clear how often those were attacked in those months.

[Carl Schwamberger]

Let me rephrase the question: If a 500 lb bomb destroys a section of track, ergo a 'cut", then what would 6x 500lb bombs dropped in a tight, overlapping line constitute, a cut or 6 cuts?

A cut. If it were six bomb cuts spread over 20 kilometers they might count it as six cuts, but in general a cut was caused by the attack of a squadron element on a single section of line. Line cuts were also only counted if they were of 24 hours duration or greater, so they were more of a moving figure than bridge cuts. For example, in the region Ouest on 10 June there were 35 line cuts, 48 on 30 June, 37 on 25 July, and 9 on 31 July.

These line or track cuts became regarded by air crew as a waste. The repair workers had prepositioned ballast, sleepers and rails dispersed along the railways. Filling in a single 500lb bomb crater & reconnecting the track could be accomplished in hours. (Unless the SS killed your repair crew, but thats a different story.) Conversely bridges averaged weeks to replace. Months for the larger rivers.

Line cutting also involved the strafing of locomotives and trains. From 21 May to 5 June, it was estimated that 310 were damaged in region Ouest and 490 between 6 June and 31 August. That damaged added to the burden of the rail repair crews.

This over the long haul was productive. Rundsteads staff in February or March 1944 was predicting a complete collapse of military railway traffic in 3-4 months. Between looting of rolling stock for use in Germany & the east, declining replacement manufacture, and Allied attacks ramping up from 1943 the rail capacity was insufficient at the end or 1943 & decline was seen as accelerating.

[/quote]The last component were attacks on rail centers, especially marshaling yards and rail maintenance and repair facilities. In combination, it resulted in an average of 9.5 of the 13 main line routes closed in region Ouest during June and July, 5.3 to bridge cuts, 3.1 to track cuts, and 1.1 to rail center cuts.
[/quote]

Damage to the service facilities and loss of rolling stock in the Marshalling yards dovetailed with the previous point about direct attacks on the trains. It took longer to restore the tracks in the yards, but it was still relatively quick. The airlway services did stretch things out through a system of dispersal of repair facilities and marshaling service, creating a lot of small and hard erto locate targets. But, those were less efficient/productive as well.