Battleship Vittorio Veneto

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Gary
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Re: Battleship Vittorio Veneto

Post by Gary »

I think The only modern Battleship a VV came close to engaging was Prince of Wales during Operation Halberd.
If the Prince had caught her and engaged her long enough to allow Rodeny to catch up it could have been a repeat of Bismarcks final battle
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Dave Saxton
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Re: Battleship Vittorio Veneto

Post by Dave Saxton »

19kilo wrote:Good(ish) armor I guess. Too bad it couldnt stop the Fritz X.
I don't know of any battleship then existing with deck protection that could likely defeat the Fritz X. The possible exception may be Yamato, but the Musashi's deck protection was still defeated by a conventional bomb delivered by a dive bomber.
Entering a night sea battle is an awesome business.The enveloping darkness, hiding the enemy's.. seems a living thing, malignant and oppressive.Swishing water at the bow and stern mark an inexorable advance toward an unknown destiny.
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Re: Battleship Vittorio Veneto

Post by alecsandros »

Thorsten Wahl wrote: PS.
Fritz X
Fritz was released from the aircraft at a target height angle of around -65 degrees and even it falls in a slightly flatter ballistic trajectory the impact angle at the end was around 10-20 degrees from the normal, impact speed around 330+ m/s depending on height of release and could pierce then around 170 mm armor
Hi Thorsten,

I do not have the same perspective over Fritz X functionality.

"The guidance package was built around a Horn gyroscope, OPTA Radio control signal decoder, a Strassburg FuG-230b/E230 radio command link receiver, all powered by DEAG one shot batteries, and used to drive Hornasser solenoid control actuators for the ailerons and elevators.

In operation, the launch aircraft would send commands using a FuG-203 Kehl III radio transmitter, which received by the FuG-230b would be demodulated to generate steering commands for the control actuators. Eighteen preset frequencies in the 48-50 MHz bands were available. This was the first air launched Command to Line Of Sight (CLOS) guidance system ever used. A red coloured flare on the tail of the weapon was used to cue the operator when steering the weapon.

Performance claims include a glide range of 11 km for a 3,300 ft AGL release, and speeds between 235 and 486 KTAS. "

This roughly translates into 11.000m glide for a 1000m drop, or a 8.18* gliding angle, from the horizontal. Asuming a horizontal flat armor plate, the angle of impact would be 81.82* from the normal...

Furthermore:

"The new SD-1400X used a cruciform wing, angled at 28 degrees, and a segmented annular tail, with electromagnetically activated spoilers for pitch and yaw control. Experiments with pneumatic actuators are claimed to have caused problems at low ambient temperatures. The annular tail arrangement was intended to introduce drag at high speed and thus limit weapon terminal velocity, which proved an early impediment to accurate aiming - nevertheless the weapon's terminal velocity was transonic. Part of the tail was electrically insulated to act as a conformal antenna for the radio link. "

"The spoiler arrangement was situated between boundary layer fences, and six pairs were used, two pairs in the guidance control loop for pitch/yaw steering, and one pair for roll stabilisation, controlled by the rate gyro. Claimed trial Circualr Error Probable was 100 ft. "

"The operator tracked the weapon through the standard Lofte 7 bombsight, using a smokeless white/blue tail mounted flare or lamp, after problems with flare smoke plumes and green or red flares. Flare reliability is claimed to have been a problem. The guidance package was powered by a 24 Volt battery, this including the command link receiver, roll stabilisation loop and actuators. The weapon was to designed to be compatible with a range of FuG-203/FuG-230 datalinks up to the Kehl IV variant. An attempt to adapt the Duran/Detmold FuG 208/238 wire guidance system was abandoned. The guidance package was externally heated by air from the launch aircraft's deicing system prior to launch.

The SD-1400 delivery profile involved typically overflight at 20,000 ft AGL, bomb release after throttling back, with the bombardier then using a joystick to steer the bomb until impact.
"

I also have the following picture about the sinking of battleship Roma:
Image

My impression is that the bomb is gliding towards Roma, and not at all falling close to the normal.

====

The steering mechanism of the gldier-bomb allowed for changes in the angle of impact. However I doubt the operator in the bombardier would have the possibility of drasticaly modifying the attack angle, as the bomb's trajectory would become to difficult to observe through the bomsight. In practical terms, I would see it as a modification from danger space to hiting space, which I don't find realistic given the optical constraints.

Consequently, I don't know if the bomb's perforating capabilities were so extreme as one might think, coming from a 1.3 tons projectile. My intuition is that the claimed 130mm of homogenous armor is the best lead we've got. This coming at a realistic impact angle of 45-60* from the normal, if not more.

Cheers,
Alex
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Re: Battleship Vittorio Veneto

Post by Thorsten Wahl »

Performance claims include a glide range of 11 km for a 3,300 ft AGL release,
this belongs to Glidebomb HS 293
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Re: Battleship Vittorio Veneto

Post by alecsandros »

Thorsten Wahl wrote:
Performance claims include a glide range of 11 km for a 3,300 ft AGL release,
this belongs to Glidebomb HS 293
Yes, but the navigation system was the same...
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19kilo
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Re: Battleship Vittorio Veneto

Post by 19kilo »

It was imppressive.......one plane, one bomb, one modern fast battleship, at sea and manuevering...........sunk.
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Re: Battleship Vittorio Veneto

Post by Thorsten Wahl »

navigation system is not relevant for case angle
FX was a horizontal pentrator
whilst HS 293 was a vertical penetrator

some calcualation
release speed of aircraft was 300 km/h so FX got a horizontal speed of ~83 m/s
in case of Roma time until impact was ~40 Sek
at around 40 seconds after release FX acchieved ~300m/s vertical speed
using angular relationships - case angle was ~83-85 degrees
Meine Herren, es kann ein siebenjähriger, es kann ein dreißigjähriger Krieg werden – und wehe dem, der zuerst die Lunte in das Pulverfaß schleudert!
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Re: Battleship Vittorio Veneto

Post by alecsandros »

I don't know what "case angle" is.

What do you think about the picture I attached, if you say Fritz X had such a steep diving angle?
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Re: Battleship Vittorio Veneto

Post by Thorsten Wahl »

oh sorry I made a write error :oops:
83-85 must be 73-75 degrees

case angle = angle of fall

from the attached photos you cannot derive the vertical speed of the bomb and also there is no timeframe included, and FX has a starting horizontal flight speed of ~ 83m/s wich should be roughly the same at the complete time of the bombfall.
Meine Herren, es kann ein siebenjähriger, es kann ein dreißigjähriger Krieg werden – und wehe dem, der zuerst die Lunte in das Pulverfaß schleudert!
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Re: Battleship Vittorio Veneto

Post by Mostlyharmless »

Just looking at the vertical component of the velocity and the mass of the SD 1400, the armour needed to resist a Fritz-X should give you immunity to a shell from Iowa or Yamato at about 37,000 to 38,000 metres. Fritz-X was fitted with a large body to stop the terminal velocity going too close to the speed of sound, 340 m/s at sea level, as that would make it inaccurate.
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Re: Battleship Vittorio Veneto

Post by Thorsten Wahl »

Mostlyharmless wrote:Just looking at the vertical component of the velocity and the mass of the SD 1400,
wrong velocity of fall is independent from mass.

But ther is a limit of velocity somewhere dependent on the air resistance of the falling bomb.

Where does the knowledge comes from, that a projectile moving supersonic becomes inaccurate?
Meine Herren, es kann ein siebenjähriger, es kann ein dreißigjähriger Krieg werden – und wehe dem, der zuerst die Lunte in das Pulverfaß schleudert!
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Re: Battleship Vittorio Veneto

Post by Bgile »

Thorsten Wahl wrote:
Mostlyharmless wrote:Just looking at the vertical component of the velocity and the mass of the SD 1400,
wrong velocity of fall is independent from mass.

But ther is a limit of velocity somewhere dependent on the air resistance of the falling bomb.

Where does the knowledge comes from, that a projectile moving supersonic becomes inaccurate?
I don't know what his source is, but I believe that aircraft during that period tended to be come difficult to control when they approached supersonic speeds. Maybe the control surfaces lost their effectiveness after the bomb became supersonic.
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Re: Battleship Vittorio Veneto

Post by Mostlyharmless »

I also don't know the best source for this. An article "The Dawn of the Smart Bomb" at http://www.ausairpower.net/WW2-PGMs.html says "The annular tail arrangement was intended to introduce drag at high speed and thus limit weapon terminal velocity, which proved an early impediment to accurate aiming - nevertheless the weapon's terminal velocity was transonic." My understanding was that there was quite a lot of wind tunnel development before a working bomb was developed and that much of the the structure added to the SD 1400 was designed to reduce the terminal velocity. Of course the added structure meant that it no longer fitted in a bomb bay and this made it harder to supply heating to ensure that the gyros were not frozen when it was dropped which all helped to keep the design team busy.
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Re: Battleship Vittorio Veneto

Post by Mostlyharmless »

However, the fins are also needed to supply "lift" when the controls change the angle of attack. There is more information at http://www.warbirdsresourcegroup.org/LRG/fritz.html. I confess that I had believed that the bomb was surrounded by a case to make it fatter and slower but that may not be true.
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Re: Battleship Vittorio Veneto

Post by lwd »

Thorsten Wahl wrote: wrong velocity of fall is independent from mass.
But ther is a limit of velocity somewhere dependent on the air resistance of the falling bomb.
Not quite right. The acceleration due to gravity is independent of mass as is the force of friction. However this means that the accereation due to Friction equals the frictional force divieded by the mass of the object and terminal velocity is where the two accerations are equal.
Where does the knowledge comes from, that a projectile moving supersonic becomes inaccurate?
The science of how to use control surfaces in the supersonic region was rather new at the time. The faster a projectile is moving the harder it is to steer as well. Artilery shells were supersonic and relataivly accurate but unguided. Then there were things like compressabilty that come into play near the sound barrier. The stresses of going transsonic are also significant.
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