B-17s in Pacific during WW2 hypothetical

wrote:

On 5 Oct 2005 12:18:58 -0700, wrote:

I'm aware that B-17s attacked Japanese Shipping during WW2
(battle of Midway comes to mind), but that they were way too
high and didn't hit anything.

Targets moving at 25+ kts. are difficult to hit.

Speaking hypothetically, would it have radically improved anthing
if the B-17 attacked from a much lower altitude?

Yes.

A lesser time of fall, certainly.
There were, apparantly some extreme examples. I've hears stories of
B-17s making night skip-bombing raids on Rabaul Harbor.

I'm thinking that the B-17 was a pretty tough plane, as proven
over bombing raids in Europe. And wonder if it could
survive the AA and CAP that the Japanese put up that so easily
downed the Vindicators? Speed and multiple engines come to
mind.

So do 8th AF losses over Europe to flak and fighters.

It's a big target, and a head-on run at a ship is a zero deflection
shot by its AA gunners.

Of course if the ships are inadequately protected or you can
overwhelm the defenses then you might be able to reprise the fate of
HMS PRINCE
OF WALES and REPULSE.

Most of the damage to Repulse and Prince of Wales was by torpedoes,
IIRC.

Still, would bombing accuracy have improved to a point that
hitting a Japanses CV would have been possible.

Yes, if you were willing to take the casualties.

I have this (crazy?) picture of a B-17 lining up with a Japanese
carrier (lengthwise) and dropping a stick of bombs on it. Wonder
what the spread would be at different speeds and the intervals
between bombs. Thanks, to the SBDs, this was not needed, but
just curious.

In horizontal bombing of a moving target you aim your bombs where
the
target will be, not where it is. (Query: could the Norden
bombsight factor in target speed, or was it designed to only engage
stationary
targets?) The captain of the target is watching the bomber and can
see the release. The ship is also manuevering to deny the bombadier
that nice target line that you desire!

The Norden worked by tracking the target - the Bombardier put the
crosshairs on the target, and started tracking it manually (Twist
knobs to keep the crosshairs on target) When the sight was properly
tracking, it would keep the crosshairs on target by itself. When the
appropriate release point was reached, as determined by the
airplane's altitude, speed, attitude, (You could be climbing or
gliding with a Norden, within certain limits) the ambient conditions,
and the bomb's ballistic characteristics as dialed into the sight, it
would automatically release the bombs.
There was a minimum altitude, which was driven by how fast the sights
tracking motors could drive the crosshairs.
So - since you weren't squinting at a spot on the ground, but
tracking the target relative to the bomber, it would compute for a
moving target. The Norden was developed by the Navy, y'know. I
think they had ships in mind. Every Torpedo Bomber could carry one,
for use in their level bombing role (Which they rarely did), and
every Patrol Bomber carried one.
The drawbacks are that if the ship jinks, it screws up the tracking
solution, and you've got to re-synchronize and let the sight settle.


Terminal velocity of the bomb is about 800 ft./sec. (per
naca.larc.nasa.gov/digidoc/report/tr/79/NACA-TR-79.PDF ). So for
every 5000 feet of altitude the bomb has to travel the ship's
captain
has about 6.25 sec. to get out of the way. Actually, he has a bit
more because the bomb has to fall some distance to achieve terminal
velocity. Then there's aircraft drift, wind, sea state, etc. to
consider. Not a simple problem, eh? :-)

That speed depends on the bomb. It's about right for a GP bomb shape,
but an Armor Piercing Bomb would fall faster.
But you're right - that bomb's falling a long time. It doesn't take
much to make it miss.

Come to think of it, the Carriers would and did perform evasive
movements, so skip that requirement that the B-17 would
line up with the keel of the carriers.

Ayup. :-)

Who was pretty good glide bombing in a Stoof using "Kentucky
Windage"!

The other options are skip bombing (A low fast approach, dropping the
bombs well short, and having them skip off the water into the ship's
side down near the waterline. The problems are that you've got to
fly straight at the target, giving his now highly motivated AA
gunners an easy no-lead shot, and the fact that you and the bomb will
be arriving at the ship at the same time. You can get hot with the
bomb, or, if it fuzes early, it blows up underneath you.
The other option is torpedoes. Army Medium Bombers - the early B-25
and B-26 in particular, could carry torps. The only problem, (Other
than the alien notion that the Army would drop torpedoes) was that
those airplanes really didn't like to slow down to the roughly 90 Kt
airspeed that was necessary to keep the torpedo from breaking up.

--
Pete Stickney
Java Man knew nothing about coffee.

On Thu, 06 Oct 2005 00:56:43 -0400, Peter Stickney
wrote:

snipped for brevity here and there

Of course if the ships are inadequately protected or you can
overwhelm the defenses then you might be able to reprise the fate of
HMS PRINCE
OF WALES and REPULSE.

Most of the damage to Repulse and Prince of Wales was by torpedoes,
IIRC.

You might be right. Of course, the torpedo bombers at Midway suffered
massive casualties because the targets were well protected by fighters
and motivated AA crews. If you can split the defense using a "HI-LO"
sort of attack (which was the tactic, IIRC) then your torpedo aircraft
might fare better.

The Norden worked by tracking the target - the Bombardier put the
crosshairs on the target, and started tracking it manually (Twist
knobs to keep the crosshairs on target) When the sight was properly
tracking, it would keep the crosshairs on target by itself. When the
appropriate release point was reached, as determined by the
airplane's altitude, speed, attitude, (You could be climbing or
gliding with a Norden, within certain limits) the ambient conditions,
and the bomb's ballistic characteristics as dialed into the sight, it
would automatically release the bombs.
There was a minimum altitude, which was driven by how fast the sights
tracking motors could drive the crosshairs.
So - since you weren't squinting at a spot on the ground, but
tracking the target relative to the bomber, it would compute for a
moving target. The Norden was developed by the Navy, y'know. I
think they had ships in mind. Every Torpedo Bomber could carry one,
for use in their level bombing role (Which they rarely did), and
every Patrol Bomber carried one.
The drawbacks are that if the ship jinks, it screws up the tracking
solution, and you've got to re-synchronize and let the sight settle.

Thanks for info on the Norden. I was not aware of its roots.

Terminal velocity of the bomb is about 800 ft./sec. (per
naca.larc.nasa.gov/digidoc/report/tr/79/NACA-TR-79.PDF ). So for
every 5000 feet of altitude the bomb has to travel the ship's
captain
has about 6.25 sec. to get out of the way. Actually, he has a bit
more because the bomb has to fall some distance to achieve terminal
velocity. Then there's aircraft drift, wind, sea state, etc. to
consider. Not a simple problem, eh? :-)

That speed depends on the bomb. It's about right for a GP bomb shape,
but an Armor Piercing Bomb would fall faster.
But you're right - that bomb's falling a long time. It doesn't take
much to make it miss.

IIRC an AP has to hit a solid target to detonate. A GP bomb would
often detonate at water entry, or could be fitted with a shallow depth
fuse (I don't know if an AP bomb could be similarly fitted). While a
hit is better than a miss, a near miss by a large GP bomb can still
cause significant damage to a ship by weakening or opening seams.
Multiple near misses can be fatal.

Come to think of it, the Carriers would and did perform evasive
movements, so skip that requirement that the B-17 would
line up with the keel of the carriers.

Ayup. :-)

Who was pretty good glide bombing in a Stoof using "Kentucky
Windage"!

The other options are skip bombing (A low fast approach, dropping the
bombs well short, and having them skip off the water into the ship's
side down near the waterline. The problems are that you've got to
fly straight at the target, giving his now highly motivated AA
gunners an easy no-lead shot, and the fact that you and the bomb will
be arriving at the ship at the same time. You can get hot with the
bomb, or, if it fuzes early, it blows up underneath you.

Skip bombing was widely used against merchant targets, but it's more
problematical against a warship due to the volume of AA fire the crew
faces. I see it as VERY costly against a high value military target
surrounded by a screen of escorts in an AA formation.

The other option is torpedoes. Army Medium Bombers - the early B-25
and B-26 in particular, could carry torps. The only problem, (Other
than the alien notion that the Army would drop torpedoes) was that
those airplanes really didn't like to slow down to the roughly 90 Kt
airspeed that was necessary to keep the torpedo from breaking up.

Skip bombing and torpedo attacks have the same difficulty: you have to
get in close to the target, slow and at low altititude. Against
merchant ships this is a doable thing. Against a properly protected
high value target you will loose a LOT of aircraft (a la Midway).

Bill Kambic

wrote:

On Thu, 06 Oct 2005 00:56:43 -0400, Peter Stickney
wrote:

snipped for brevity here and there

Of course if the ships are inadequately protected or you can
overwhelm the defenses then you might be able to reprise the fate of
HMS PRINCE
OF WALES and REPULSE.

Most of the damage to Repulse and Prince of Wales was by torpedoes,
IIRC.

You might be right.

He is. All the significant damage was due to torps. IIRR Repulse suffered
either one or two hits by 250kg.bombs, but the damage was relatively minor.
It was the five torp hits that sank her, and the 7 or so (and no bomb hits
IIRC) that did for PoW.

snip

The Norden worked by tracking the target - the Bombardier put the

crosshairs on the target, and started tracking it manually (Twist
knobs to keep the crosshairs on target) When the sight was properly
tracking, it would keep the crosshairs on target by itself. When the
appropriate release point was reached, as determined by the
airplane's altitude, speed, attitude, (You could be climbing or
gliding with a Norden, within certain limits) the ambient conditions,
and the bomb's ballistic characteristics as dialed into the sight, it
would automatically release the bombs.
There was a minimum altitude, which was driven by how fast the sights
tracking motors could drive the crosshairs.
So - since you weren't squinting at a spot on the ground, but
tracking the target relative to the bomber, it would compute for a
moving target. The Norden was developed by the Navy, y'know. I
think they had ships in mind. Every Torpedo Bomber could carry one,
for use in their level bombing role (Which they rarely did), and
every Patrol Bomber carried one.
The drawbacks are that if the ship jinks, it screws up the tracking
solution, and you've got to re-synchronize and let the sight settle.

Thanks for info on the Norden. I was not aware of its roots.

For a history of the Norden as well as most other pre-war US (and allied)
bombsights, see "America's Pursuit of Precision Bombing, 1910-1945", by
Stephen L. McFarland. The book includes details of how it worked, the
political fight between the navy and the Army over control of production
and access to it, development and production issues, German pre-war
espionage that rendered moot most of the elaborate wartime security
measures (they had a similar tachymetric bombsight of their own), accuracy
achieved in test and combat, statistical studies of the factors that
degraded accuracy, and so on.

snip

Guy