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Author Topic: Torpedo Parameters  (Read 5880 times)
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MackStones
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« on: January 03, 2013, 11:07:59 AM »

When flying, I've been getting more questions about the torpedo drop parameters.  Despite reading the official 4.10 parameters and doing some testing, I've had trouble getting torps to work right most of the time.  I wanted to put together stuff I've found on the issue, and encourage others to chime in.

From the 4.10 Manual:

Realistic Torpedoes
WWII aerial torpedoes were delicate equipment that needed be dropped with some
precautions. Each torpedo type had an optimum altitude and speed of drop that allowed it to
hit the water with a determined, optimum angle. If the angle was bigger, the torpedo tended
to sink. If it was smaller, it did not enter the water and skipped on the surface. Also, the
torpedo could not be dropped from too high altitude, because if it impacted the water too
hard, its internal mechanism could be damaged.

Each torpedo type in IL-2 has its optimum drop parameters, of course some error is allowed,
but not too much.

• LT F5W (Italian Whitehead)
100m, 300Km/h

• LT F5B
40m, 250Km/h

• Mk13, Mk13a
30m, 205 km/h

• Mk13 late
180m, 400 km/h
(this torpedo had a much wider range of drop than the early one)

• Type91
30m, 240 Km/h

• Type91 late
60m, 330 km/h
(this torpedo had a much wider range of drop than the early one)

• 45-17
30m, 205 km/h

Also torpedoes had to run for some time into the water to arm their warhead, so torpedoes
cannot be dropped too close to the ship (distance should be bigger than 400-600 meters).
Torpedoes dropped on ground or directly on the ship (without hitting water) will not explode.

Circling Torpedoes
This patch also brings two new examples of torpedoes which are circling torpedoes that had to
be dropped from a safe height in areas such as harbours that were crowded with enemy ships.
These torpedoes run in circles for some time, if no ship was hit they self-destroyed.
Motobomba FFF and 45-36AV-A are the circling torpedoes implemented in IL-2.

Motobomba FFF (LT 350)
This weapon was designed by Italian designers Frefi, Filpa and Fiore (hence the name FFF).
The FFF was a 500 millimeters (20 in) diameter electric torpedo. It was dropped from high
altitude, a first small parachute was used to stabilize and keep a low fall velocity; around 200
m of height, a bigger parachute deployed, to assure a softer impact into water. The torpedo
26 / 35 was designed to steer concentric spirals until it found a target. It weighed 350 kilograms, and contained a 120 kilograms warhead. Its speed was about 15 knots and it had an endurance of
15–30 minutes. The FFF was used in small numbers and without success against Gibraltar, Alexandria and during convoy battles in August 1942. Later it was adopted by the Germans as the LT 350 and, used in larger numbers. It scored some successes against moored ships at Tripoli, Bone and Bari.

45-36AV-A
This Russian torpedo was based on submarine torpedo 45-36 (which in turn was based on
Fiume design). Adopted in 1939, it had a speed of 39 knots and a range of 4km. Drop height
was about 2000-3000m.

Torpedo-Kommandogerät
ToKG device is like a simplified torpedo data computer found in submarines. ToKG sets the
torpedo gyro angle which turns the torpedo once it enters the water. For example angle +30
would turn the torpedo 30 degrees to right. ToKG needs two input parameters from the player.
Target ship’s speed in knots and ship’s AoB (Angle-on-Bow).  ToKG is used with the old bombsight speed & side slip keys. Speed keys are used to input target ship’s speed in knots to ToKG. Side slip keys are used to input ship’s AoB (Angle-on-Bow).  Optional spread parameter can also be adjusted with bombsight angle keys. Increasing spread angle means that torpedoes will have different paths and therefore chances of hit can increase. Setting a spread of 6° means that left side torpedo will curve 3° to left and right side torpedo will curve 3° to right. The idea of the ToKG is to input these two parameters to the device which then calculates a correct torpedo gyro angle and feeds it to the torpedo. This way the pilot doesn’t need to estimate the angle and steer plane to take needed lead before the torpedo is released. With ToKG the pilot always aims the plane directly towards the target ship. Anyone who has played submarine simulations, knows that besides target ship’s speed and AoB, distance to the ship has also some effect to the torpedo gyro angle. However when the distance changes, angle remains somewhat constant. The optimum torpedo release distance for ToKG use is 2000 meters from the ship.  ToKG can be found from Ju 88A-4/Torp, Ju 88A-17 and He 111H-6 when torpedoes are carried. 

From WOP Forum Posts:

regarding circling torpedoes:

   drop it above 300/400 meters over the ships, and wait for a hit

   have had some success with 300kph/300m drops with this torp!

regarding Fw-190A-5 Torp. "Fiume" Torpedo (which is a UP3 add-in, not 4.10, and presumably is the same as the LT F5W Whitehead since Whitehead had a torpedo factory in Fiume)

   For the torpedo carried by FW-190 A-5/U-14 , I suggest this :
250 km/h and 50 m.

regarding the LT F5W:

I was getting some good runs with the LTW and LTW5 at 100m/300kph and 75m/300kph respectively. I tried to calculate the min/max parameters flying offline, but offline flight seems to have wider margins of error

From Posts in Other Forums (technically, Fora):

After training a couple of hours on the Quick Mission Generator with a Ju-88 and a SM-79 against a Target:Ship a got a 80%-90% success rate on dropping and hitting the ship. The trick is to know the appropriate speed and altitude limits of the torpedo, then get close to the ship at 50m above that limit, drop your nose a little and release during that slight dive at the right altitude. I drop them very close to the ships, around 400m and they always explode. But if I can carry bombs with anything, I always preferred the big explosive contain of them to the tiny torpedoes warheads.




Based on some quick tests using the TBM3 and the Kate, I have found the following speeds and altitudes effective for launching Mk13 and Type 91 torps.

Mk13:

Lowest successful altitude: 60
Highest successful altitude: 140

Speed range: 120-134 (you might be able to go slower but anything slower than 120 and you risk losing too much altitude)

Cruising methods:

Speed 120 = 44% throttle w/ combat flaps (slight altitude decline over time)
Speed 130 = 47% throttle w/ combat flaps (negligible altitude decline over time)
Speed 134 = 48% throttle w/ combat flaps (no altitude decline or increase noticed)

Type 91:

Lowest successful altitude: 13 (recommend 20, since 13 requires a very low speed)
Highest successful altitude: 50

Speed range: 110-150

It was rather hard to try and maintain altitude and modify speed to test all desired options so for this one I'm going to give you successful drop alt/ias combos. You can extrapolate from there

Alt 13 / IAS 110 = 47% throttle w/ combat flaps (slight alt decrease over time. Not recommended unless you started out with an alt of 20)
Alt 40 / IAS 120 = 52% throttle w/ combat flaps (slight alt increase. Might want to be at 30 since anything above an alt of 50 might not make it)
Alt 40 / IAS 150 = 66% throttle w/ raised flaps (no alt variation detected)

That last one surprised me, and it is also fairly easy to drop to a speed of 150 after diving from higher altitude and the increased speed means you're less likely to get picked off too easily


All things considered, I found using the TBM was much easier. It responded to controls way better and has a much better torp range imo. Also, the damn Altimeter on the Kate is too F'ing low on the dashboard! I would like to be able to see it AND the horizon at the same time, and when I'm at the proper Alt and heading THEN I look down to adjust my speed... with the Kate I have to dip down, look down... still too high... look up, dip down, look down.... oops, too low... upsie-daisy... look down, ok that's good... throttle back and adjust speed and hope to GOD I didn't overshoot the target already




 IL-2 Torpedo Parameters
• Mk-13~100mph/0ft
• Mk-13 (late)~200mph/200ft
• Type 45-12~150mph/50ft
• Type 91~150mph/150ft
• Type 91(late)~ 150mph/150ft
• LT F5b~150-180mph/150ft
• LTF5W~150-180mph/150ft





Yes, this all started with 4.10 and was made an option in 4.11 by switches in the arming screen for bomb fuzing and realistic torpedos. The official parameters I listed don't always work 100% of the time however... there seems to be another factor or randomness here that effects the "torpedo entering the water" but I can't quite figure it. It might be that a perfectly level aircraft attitude is required at release. Anyway, even if I'm perfectly within parameters it sometimes still breaks when entering the water.

Here's the specs I use (they are converted to feet and MPH and adjusted to the low side of the specs to minimize the occasional failure even when within the drop parameters) It also helps to use a speedbar mod to show MPH in 1 MPH increments and altitude in 5 feet increments. Example: while the stock speedbar might read 90 feet you could be really at 99 feet, or 120MPH when you are actually going 129MPH thus spoiling the drop.

• Mk13, Mk13a
120 mph (205kph)
90 ft (30m)
-----------------------------------------------
• Mk13 late
240 mph (400kph)
590 ft (180m)
-----------------------------------------------
• British Mk13 (RC4 only)
240 mph (390kph)
900 ft (280m)
-----------------------------------------------
• LT F5B
150 mph (250kph)
130 ft (40m)
-----------------------------------------------
• LT F5W (Italian Whitehead)
180 mph (300kph)
320 ft (100m)
-----------------------------------------------
• Type91
140 mph (240kph)
90 ft (30m)
-----------------------------------------------
• Type91 late
200 mph (330kph)
190 ft (60m)
-----------------------------------------------
• 45-17
120 mph (205kph)
90 ft (30m)
-----------------------------------------------

Torpedo release distance should be greater than 1200 / 1800 feet from a ship to allow for arming.
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CIA_Luth
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« Reply #1 on: January 03, 2013, 11:24:51 AM »

wow,  thats a lot of information.  thanks for your hard work Mack.  im going to copy this thread and put it on my desktop for a quick reference.  thanks!
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CIA_Luth
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« Reply #2 on: January 03, 2013, 11:33:12 AM »

BTW, in the mission Eisbar, the arming screen for the FW torp lists a particular type of torpedo,  which is i believe the italian whitehead you mentioned.  but,  when i checked my loadout in my personal stats, it lists the torpedo as the LT5FB,  which has different drop parameters.  maybe this is a bug in the mission?  or i missed something at the arming screen.  ill look again next time the mission comes up.  but this could explain why we were experiencing torpedo drop failures.
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MackStones
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« Reply #3 on: January 03, 2013, 12:09:54 PM »

Very interesting.  I'll do some more searching.

It does make some sense because the parameters given on the WoP Forum post for the Fw-190 torp seem to match those of the LT5FB more than those of the Whitehead.
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Drawbar
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« Reply #4 on: January 06, 2013, 06:05:03 PM »

There seems to be some difference betw HSFX an UP.

Same B5N2 parameters I always used in UP results in a fail in HSFX.

These settings work 100% for both B5N2 torps in UP.


HSFX uses different cockpit, maybe that has something to do with it.

DB
« Last Edit: January 06, 2013, 06:20:38 PM by Drawbar » Logged

KU_rigamortis
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« Reply #5 on: January 07, 2013, 01:09:39 AM »

Different gauge increments

« Last Edit: January 07, 2013, 01:16:05 AM by KU_rigamortis » Logged
Sorbifer
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« Reply #6 on: January 07, 2013, 04:55:45 AM »

It looks like a flat and stable flight 50m over the water, 140kph, right? Picture above the same, just a bit faster... There is no need in Kates to make a little move down right in the moment of dropping torpedoes, just like in Italian plane?
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OstBlock.
Sorbifer.
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wespe
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« Reply #7 on: January 07, 2013, 04:37:23 PM »

Sorbifer,
  There is no need to move the nose up or down when launching a torpedo.  That tactic is just for the uneducated and people who write comments on YouTube.  Keep the plane level and use good data.

Japanese Torpedo Data:
Type 91
  Drop Height:  20m -60m
  Drop Speed:  135 - 155 kias

Type 91 Late
  Drop Height:  20m-70m
  Drop Speed:  135 -165 kias

Here's some photos I posted a year ago, which Faust kindly put in a "Tips and Tricks" thread on the Zeke's forum.

Here's how it looks on the gauges.

B5N2 (Kate):
(showing 145 kias and 50m)




G4M1 (Betty)
(Airspeed gauges indicate 135 and 146 kias but what I really wanted to show was what the drop altitudes looked like on the gauge.  To be safe, I'd drop when the needle just touches the top of the mark designating zero.  That should put you in the 30m to 40m alt. range) 




Changes:
Those boobs at HSFX, in their infinite wisdom, decided to change the interior of the B5N2 Kate.  At higher torpedo dropping altitudes it's difficult to see the target ship as it disappears under the nose of your aircraft too soon.  I recommend dropping from 25m.

G4M1 Betty:  The old Betty had the altimeter in 250m increments.  The HSFX version has it in 50m increments.  Not that big of a deal.  Just drop your torpedo when the needle touches the side of the zero mark as shown above and you'll be fine.

     

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