Bomber vs fighter

[pbehn]

Thought you might be interested in this version of the B-17:
https://en.wikipedia.org/wiki/YB-40_Flying_Fortress

Splitting hairs but the YB 40 had an essential element of a bomber missing, no bombs.

 

[GrauGeist]

Thought you might be interested in this version of the B-17:
https://en.wikipedia.org/wiki/YB-40_Flying_Fortress

The YB-40 and XB-41 concepts were failures...

They were so heavy, they were unable to keep up with the standard bombers after they had dropped their bomb load.

A good idea but a failure...

 

[pbehn]

The YB-40 and XB-41 concepts were failures...

They were so heavy, they were unable to keep up with the standard bombers after they had dropped their bomb load.

A good idea but a failure...

And so slow in the climb they were difficult to form up with

 

[mig-31bm]

The YB-40 and XB-41 concepts were failures...

They were so heavy, they were unable to keep up with the standard bombers after they had dropped their bomb load.

A good idea but a failure...

why dont they just let yb-40 fly together instead of with normal bomber ? , i mean with 30 machine gun and heavy armor they seem quite invulnerable

 

[mig-31bm]

Germans weren't firing Werfer-Granate 21 a single bombers but at formations. And even then it was not with the expectation of hitting a bomber (they were using time fuses) but of coming close enough to damage one or more while breaking up the formation/s so that gun attacks would be more effective.

The R4M wasn't a long range stand off weapon either, despite what Wiki says. lets look at it shall we?

"The anti-aircraft version of the R4M used a large warhead of 55 mm. with 520 g. (17.6 ounces) of Hexogen explosive charge, nearly guaranteeing a fighter kill with one hit. Each R4M weighed 3.2 kg and was provided with enough fuel to be fired from 1000 m., outside the range of the bomber's defensive guns."

Now that certainly sounds like a stand off weapon but one line later;

"A battery typically consisted of two groups of 12 rockets and when all 24 were salvoed in an attack, they would fill an area about 15 by 30 m. at 1000 m., a density that made it almost certain that the target would be hit. The R4Ms were usually fired in four salvos of six missiles at intervals of 70 milliseconds from a range of 600 m"

So what was the range?
And then we have this line "The Luftwaffe found the R4M missiles to have similar trajectory to the 30 mm MK 108 cannon in flight, therefore the standard Revi 16B gunsight could be utilized."

Now the 30 mm MK 108 had a MV of 500 m/s and the Luftwaffe gave an absolute maximum combat range of 900 meters at 3000 meters altitude and 1100 meters at 6000 meters altitude (thinner air) and an effective range of just 400 meters against bombers( it would be shorter against fighters) for the 30 mm MK 108.

600 meters is within the effective range of .50 cal machine guns mounted in power turrets.

I am not sure where the 15% accuracy figure for the Werfer-Granate 21 comes from as the math doesn't work quite right. Best case from the Wiki entry "While a single fighter's payload of two or four such rockets was extremely unlikely to score a hit, a mass launch by an entire fighter squadron (12-16 aircraft) as it arrived to intercept the bombers would likely score two or three hits, about 15% accuracy" is 12 aircraft at 2 rockets apiece (24 rockets) getting 3 hits which would be 12.5%. 16 fighters firing 2 apiece and getting two hits would be 6.25%. Please note that blast radius of 15meters from the 40.8 (90lb) warhead helped.

And " The low launch velocity also meant accurate aiming was difficult, as it was for the attacking pilot to accurately judge the distance to the target. As a result most of the rockets fired exploded either in front of or behind the bomber target. However, they did often achieve the effect of opening up the bomber formations enough for fighters to attack with conventional weapons."

The rockets sound cool but in actual fact never quite lived up to the hype, and this goes for the American, British, French and Soviet rockets of the 1950s too, Despite much money, time and effort.

See:
View: https://www.youtube.com/watch?v=Z_nAjPLlCKk

 

[pbehn]

why dont they just let yb-40 fly together instead of with normal bomber ? , i mean with 30 machine gun and heavy armor they seem quite invulnerable

Why would you attack an aeroplane that has no bombs? even a formation of them.

 

[mig-31bm]

Why would you attack an aeroplane that has no bombs? even a formation of them.

oh yeah , just realise that they can't carry bomb , but wait they actually faster than b-17

YB-40
Maximum speed: 292 mph (470 km/h)
Cruise speed: 196 mph (315 km/h)
B-17G
Maximum speed: 287 mph (249 kn, 462 km/h)
Cruise speed: 182 mph (158 kn, 293 km/h)

also it unlikely that the German know which airplane have bomb and which one doesn't

 

[Balljoint]

And that illustration gives a good idea of how little the B-17 was actually protected. The flight deck was afforded some protection *if* the attacking fighters followed Boeing's design, but they didn't. The windscreen wasn't armored glass, the nose dome was plexiglass, the side windows and observation dome just ahead of the cockpit wasn't armored.

Add to that, the gunner's positions afforded little protection and the tail gunner had little or no protection until the "Cheyenne Hood" was adopted and even then, the only real armor was a reinforced plate of glass. If you've ever read any accounts (or spoke with veteran crewmembers) of missions, there's plenty of stories retelling how schrapnel or MG/cannon fire ripped through the fuselage of the bomber, and the projectiles rarely passed through harmlessly.

And the larger the caliber, the more the damage, plus no amount of armor aboard the B-17 protected the crew from the 30mm minengeschoss round of the Mk103/108 cannon.

We've seen the effects of up-armor in the way of speed penalties with the YB-40 project.

And just to clarify, the chin turret wasn't incorporated into the B-17 until after the failure of the YB-40 project in 1943, the last of the B-17Fs being outfitted with the modification nefore the switch to the B-17G production.

There was some additional "armor" in the in the form of nylon antiballistic mats. These seem to be intended as protection against FLAK fragments and would probably not handle a hot round. I bought some surplus mats for protection against failed automotive flywheels. Fortunately, I have no idea if they would have helped.

 

[GrauGeist]

why dont they just let yb-40 fly together instead of with normal bomber ? , i mean with 30 machine gun and heavy armor they seem quite invulnerable

Only a few were field modified with a higher number of MG, the standard build included about 14 .50 cal. MG.
These positions were:
Chin turret: 2x.50
Dorsal turret: 2x.50
Ventral turret: 2x.50
Starboard waist: 2x.50
Port waist: 2x.50
Ball turret: 2x.50
Tail: 2x.50
Total: 14x.50
Standard field upfit: "Cheek" positions restored (1x.50 per side) brought the total number to 16x.50


So because with all the additional turrets and ammunition aboard, the aircraft wouldn't be able to carry the additional weight of bombs. Also keep in mind that the YB-40 was not only carrying more weapons, ammunition and armor but it was also suffering from decreased aerodynamics because of it's additional armament.

YB-40:
Empty Weight: 54,900lbs. (24,900kg)
Loaded Weight: 63,500lbs. (28,800kg)
Ammunition total: 10,700 (+/-) rounds

B-15G:
Empty Weight: 36,135lbs. (16,391kg)
Loaded Weight: 54,000lbs. (24,500kg)

 

[gjs238]

Wonder if results would be better the other way around - no defensive armament - returns us to the Mosquito strategic bomber thread.

 

[GrauGeist]

Wonder if results would be better the other way around - no defensive armament - returns us to the Mosquito strategic bomber thread.

Even the Mosquito ran into trouble by interceptors on occasion.

It would take some serious engineering to get something the size of a B-17 to outrun fighters...it's possible but I don't think practical.

 

[pbehn]

Wonder if results would be better the other way around - no defensive armament - returns us to the Mosquito strategic bomber thread.

After the RAF started using the Mosquito they never ordered a defensive gun on a bomber. Bearing in mind that 50% of bomber losses were to flak, maybe a better strategy would be to make those bombers fly higher and faster, that is with no defense apart from speed and height with enough escorts to protect.. Teas I know...another thread.

 

[CobberKane]

It's plenty if you put them on target and a B-17 is a relatively easy aerial target. However you are likely to run out of ammo after downing a couple aircraft

Going on the Luftwaffe's experience of a 2-3 % hit rate, expending 120 rounds of 20mm should result in 3-4 hits, about one fifth of the number of hits considered necessary to achieve a 50% chance of bringing a fortress down. So you would have to be about five times as good (or lucky as the average LW pilot to have a 50/50 chance of knocking down one Fortress, and ten times as good to get two - unless there is something about the 1 v 1 scenario that tips things hugely in the fighters favour.
I am disinclined to dismiss the Luftwaffe's conclusions. These guys were a very professional force and they were collating data to support operational decisions, not for misinformation or propaganda. They were the only air force ever tasked with tackling heavy bombers on a regular basis and it was in their interests to get the best data they could. Given that modern crash site evaluations can often narrow causes down to a single failed component, I don't have any trouble believing the Luftwaffe should have gotten a reasonable handle on the number of hits on a B-17 wreck. I've never seen the actual report and I don't read German anyway, but unless the report can be disproven or the methodology brought into doubt, it seems reasonable to use it as a benchmark

 

[mig-31bm]

Only a few were field modified with a higher number of MG, the standard build included about 14 .50 cal. MG.
These positions were:
Chin turret: 2x.50
Dorsal turret: 2x.50
Ventral turret: 2x.50
Starboard waist: 2x.50
Port waist: 2x.50
Ball turret: 2x.50
Tail: 2x.50
Total: 14x.50
Standard field upfit: "Cheek" positions restored (1x.50 per side) brought the total number to 16x.50


So because with all the additional turrets and ammunition aboard, the aircraft wouldn't be able to carry the additional weight of bombs. Also keep in mind that the YB-40 was not only carrying more weapons, ammunition and armor but it was also suffering from decreased aerodynamics because of it's additional armament.

YB-40:
Empty Weight: 54,900lbs. (24,900kg)
Loaded Weight: 63,500lbs. (28,800kg)
Ammunition total: 10,700 (+/-) rounds

B-15G:
Empty Weight: 36,135lbs. (16,391kg)
Loaded Weight: 54,000lbs. (24,500kg)

but according to statistic they still faster , even if they are alittle bit slower than b-17 without bomb can the b-17 fly a bit slower for the yb-40 t catch up with them ?

 

[pbehn]

but according to statistic they still faster , even if they are alittle bit slower than b-17 without bomb can the b-17 fly a bit slower for the yb-40 t catch up with them ?

From what I have read here on this forum the YB 40 was heavier than a loaded B17 and the extra guns produced more drag they were slower to the target and from the target, the chronic rate of climb made real problems joining up in formation.

 

[CobberKane]

but according to statistic they still faster , even if they are alittle bit slower than b-17 without bomb can the b-17 fly a bit slower for the yb-40 t catch up with them ?

I suspect the best defence of all would always be to get out of the danger zone ASAP - loitering so a YB-40 could keep up would be counterproductive

 

[Shortround6]

After the RAF started using the Mosquito they never ordered a defensive gun on a bomber. Bearing in mind that 50% of bomber losses were to flak, maybe a better strategy would be to make those bombers fly higher and faster, that is with no defense apart from speed and height with enough escorts to protect.. Teas I know...another thread.

Not quite true. Depends on how you classify the Lincoln bomber or when it was ordered. The RAF also used B-29s as the Washington.

Higher and faster works to some extent but runs into lousier bomb accuracy which means (for targets smaller than a large city) more bombers needed to get same number of hits and more bombers means more losses. Strangely enough a single B-17 sometimes had an option available to it for evading enemy fighters. If running light ( bombs gone and around 1/2 fuel) and starting at close to 30,000ft it could actually out climb a number of different fighter types.

 

[Garyt]

Going on the Luftwaffe's experience of a 2-3 % hit rate, expending 120 rounds of 20mm should result in 3-4 hits, about one fifth of the number of hits considered necessary to achieve a 50% chance of bringing a fortress down. So you would have to be about five times as good (or lucky as the average LW pilot to have a 50/50 chance of knocking down one Fortress, and ten times as good to get two - unless there is something about the 1 v 1 scenario that tips things hugely in the fighters favour.

The reports I have read don't say a 50/50 chance of knocking down a B-17 with 20 rounds - merely that the estimate is 20 20mm rounds to knock out a B17, and that 4-5 20 mm rounds from the front would down a B-17.

That's 800 rounds fired for a non-frontal assault, or 180 rounds for a frontal assault.

I'd also guess the low chance to hit comes from pilots firing out of range or at least effective range, you more rookie pilots or those that are afraid to close.

More skilled pilots would get more rounds on target, less skilled of course less.

I think I remember reading where Saburo Sakai stated they changed to head on attacks against the B-17's.

 

[parsifal]

Not quite true. Depends on how you classify the Lincoln bomber or when it was ordered. The RAF also used B-29s as the Washington.

Higher and faster works to some extent but runs into lousier bomb accuracy which means (for targets smaller than a large city) more bombers needed to get same number of hits and more bombers means more losses. Strangely enough a single B-17 sometimes had an option available to it for evading enemy fighters. If running light ( bombs gone and around 1/2 fuel) and starting at close to 30,000ft it could actually out climb a number of different fighter types.

That has led to permutations for strikes, the so called Hi-Lo-Hi or Hi-Lo-Lo approach, over target and withdrawal. It is correct, in a general sense, that since the war, dedicated bombers have overwhelmingly sged their defensive guns and use speed and altitude to try and survive, along with various passive defences.

 

[parsifal]

I'd also guess the low chance to hit comes from pilots firing out of range or at least effective range, you more rookie pilots or those that are afraid to close

There are permutations on this as well. Some really experienced and exceptional pilots like hartmann could shoot out the centre of a dime at three miles. They were the really deadly one. but if you have a standard mount in which the armament is calibrated to converge at 250m and you start shooting at 500m, straght away you are going to reduce the possible hit rate to about 1/6 of what heat your mount is carrying. You need to have your mount set up properly to fire at a given range, or converge at a given range. its better to overestimate your convergence needs than to underestimate, because firing at ranges less than the convergence will be a lesser grouping, but still a grouping, and not sprayed allover the sky.