Graf Spee trying to escape back to Germany...

Historical what if discussions, hypothetical operations, battleship vs. battleship engagements, design your own warship, etc.
alecsandros
Senior Member
Posts: 3990
Joined: Wed Oct 14, 2009 2:33 pm
Location: Bucharest, Romania
Contact:

Re: Graf Spee trying to escape back to Germany...

Postby alecsandros » Mon Apr 06, 2015 5:51 am

... IMHO, Graf Spee's longer-ranged guns would produce earlier straddles and hits.
French 8" turrets had dispersion problems, IIRC, so obtaining 4 hits in one salvo would be exceptionally unlikely.

Long range 8" gunfire produced a ridicolusly low amount of hits. Battle of Komandorski Islands (1943) produced 0.37% hit ratio for the 2 Japanese cruisers and 0.45% for the US cruiser engaged. The first hits were scored 10 minutes after the battle commenced.

Guest

Re: Graf Spee trying to escape back to Germany...

Postby Guest » Mon Apr 06, 2015 12:16 pm

Alexandros,
Thank you for your feedback, I am trying to adjust the parameters for the simulation. I have separated the probability of gun hit in 2 main parameters: Target Acquisition and Ballistic dispersion.
The target acquisition has the following factors (for optical only in this case, no radar)
- distance
- optical signature of the target
- quality of the optical system
- crew status (combination of moral and stress)
- sea state

The ballistic dispersion parameters are:
- distance
- gun max range
- gun quality
- size of target
- speed/maneuver of the target

I agree with you that the 280mm lack of hit at the 15k/20k is overstated in the simulation, this is a bit influence by the very lucky hit on the front turret. I will run to further simulation but it is likely that I will need to adjust the ballistic side to provide more advantage to the longest range.
Your second remark on multiple hit from a salvo is correct, this rarely happen. I will check further into this and provide a mechanism to
correct.
Best Regards,
Ric

User avatar
Dave Saxton
Supporter
Posts: 2876
Joined: Sat Nov 27, 2004 9:02 pm
Location: Rocky Mountains USA

Re: Graf Spee trying to escape back to Germany...

Postby Dave Saxton » Mon Apr 06, 2015 2:42 pm

alecsandros wrote:... IMHO, Graf Spee's longer-ranged guns would produce earlier straddles and hits.
French 8" turrets had dispersion problems, IIRC, so obtaining 4 hits in one salvo would be exceptionally unlikely.

Long range 8" gunfire produced a ridicolusly low amount of hits. Battle of Komandorski Islands (1943) produced 0.37% hit ratio for the 2 Japanese cruisers and 0.45% for the US cruiser engaged. The first hits were scored 10 minutes after the battle commenced.

Agreed. The simulation doesn't have AGS scoring any hits until after 8 minutes of firing. Historically AGS had hit Exeter 4 times in the first 6 minutes from an average range of 21km, while following the Exeter through a 180* turn with its fire control. The only thing that saved Exeter at that point was the Germans shifting their fire to another target.

Additionally, AGS has radar ranging, not the French. I would expect AGS to hit first, much more often, and harder.
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.

User avatar
RF
Senior Member
Posts: 7490
Joined: Wed Sep 20, 2006 1:15 pm
Location: Wolverhampton, ENGLAND

Re: Graf Spee trying to escape back to Germany...

Postby RF » Mon Apr 06, 2015 5:23 pm

It seems that a key point here is the early interruption of fire from Anton turret.

It is not clear from this simulation whether the AGS 15 cm guns opened fire. Can you please clarify this.
''Give me a Ping and one Ping only'' - Sean Connery.

alecsandros
Senior Member
Posts: 3990
Joined: Wed Oct 14, 2009 2:33 pm
Location: Bucharest, Romania
Contact:

Re: Graf Spee trying to escape back to Germany...

Postby alecsandros » Mon Apr 06, 2015 7:19 pm

Guest wrote:The target acquisition has the following factors (for optical only in this case, no radar)
- distance
- optical signature of the target
- quality of the optical system
- crew status (combination of moral and stress)
- sea state




... It is a very complex simulation and I congratulate you on workig on it.

A thing to take into consideration though would be that Graf Spee did have and did use a gunnery radar, and that was the Seetakt of 1940 vintage. It could track a battleship at 25km with a range accuracy of 0.5%. The initial devastating salvos fired on Exeter (hit on the 3rd salvo !) were due to the Seetakt radar. After the first 10 minutes, Graf Spee suffered several 8" and 6" gun hit on her forward structures, damaging both gunnery directors and main radar.

Even so, AGS crippled Exeter (out of action for 13 months and considered to be broken up for scrap), and damaged Ajax (6 months in repair and refit) and Achilles (3 months repair and refit).

Francis Marliere
Member
Posts: 239
Joined: Mon Oct 18, 2010 3:55 pm

Re: Graf Spee trying to escape back to Germany...

Postby Francis Marliere » Mon Apr 06, 2015 8:13 pm

I would point out that even the best modelisation sometimes gives strange results. As a wargamer, I often see unexpected results in naval wargames : sometimes you can't hit a fish in a barrel and sometimes you hit against all odds. That doesn't mean that the model is bad : it's just good or bad luck.

User avatar
Dave Saxton
Supporter
Posts: 2876
Joined: Sat Nov 27, 2004 9:02 pm
Location: Rocky Mountains USA

Re: Graf Spee trying to escape back to Germany...

Postby Dave Saxton » Tue Apr 07, 2015 12:16 am

alecsandros wrote:
A thing to take into consideration though would be that Graf Spee did have and did use a gunnery radar, and that was the Seetakt of 1940 vintage. It could track a battleship at 25km with a range accuracy of 0.5%. The initial devastating salvos fired on Exeter (hit on the 3rd salvo !) were due to the Seetakt radar. After the first 10 minutes, Graf Spee suffered several 8" and 6" gun hit on her forward structures, damaging both gunnery directors and main radar.

Even so, AGS crippled Exeter (out of action for 13 months and considered to be broken up for scrap), and damaged Ajax (6 months in repair and refit) and Achilles (3 months repair and refit).


A few corrections Alex,

AGS's radar was not a 1940 model. It was installed during early 1938. Primary documents reveal that it was effective to at least 25km and as much as 30km. One account reports it was tracking Exeter from 27km. Its range accuracy was typically 100 meters regardless of range to target.

AGS only received two 8" hits during the battle. One of them was a dud.

Using the aft fire control position (which did not have a radar) AGS hit Exeter an additional three times between 0634 and 0639.
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.

ric_roc
Junior Member
Posts: 14
Joined: Tue Mar 10, 2015 3:46 am

Re: Graf Spee trying to escape back to Germany...

Postby ric_roc » Tue Apr 07, 2015 2:47 am

Thanks for the feedbacks!
I discounted the Radar firing control for the AGS based on Eric Grove's book (page 12), in a nutshell the "Seetakt" a 60 cm FuMG38G was effective to 15 km with not a sufficient bearing accuracy, the stereoscopic rangefinder was superior in bright hi-visibility conditions (13 Dec 1939). The radar was reserved for night and poor visibility. However the sources are mostly British so the usage of radar for gun control could have been unknown to them and underestimated, any German source ? (I have ordered Rosenack book, but it will take time for me as my German is quite rusted!).
For the lack of success of the 280mm there were 2 factors:
- A early hit jamming the Anton turret, putting half of the 280mm guns out of action for 19 minutes!
- The augmentation of the crews stress factor is based on being under fire and is aggravated by near misses and hits. The DKM Graf Spee was always under stress as only one of the two CA crew was under stress at any time of the action.
Note: I will also adjust the increase and the impact of the stress crew.

I will run another simulation tonight! Then I will go back to the historical simulation.

Best Regards,
Ric Roc

ric_roc
Junior Member
Posts: 14
Joined: Tue Mar 10, 2015 3:46 am

Re: Graf Spee trying to escape back to Germany...

Postby ric_roc » Tue Apr 07, 2015 2:59 am

There was a question whether the 150mm did open fire, as it was under IA control I did go back to the log files:

The 150mm opened fire at 17:13 (distance to target 18.66km). They only scored one hit. They were under local OFC!

Best Regards,
Ric Roc

ric_roc
Junior Member
Posts: 14
Joined: Tue Mar 10, 2015 3:46 am

Re: Graf Spee trying to escape back to Germany...

Postby ric_roc » Tue Apr 07, 2015 3:31 am

Simulation run #2

17:00 DKM Graf Spee discover french Cruisers in the NE, it goes on starboard at 100 increase the speed. It is early in the DKM Graf Spee cruise, max speed is 26kn.

17:01 The french Cruisers picked up the dark smoke of the DKM Graf Spee engines on SW and power up to full speed on 170

17:05 As the French Cruisers are now less than 25km away the DKM Graf Spee open fire on the MN Dupleix

17:08 The French Cruisers open fire at 23km

17:11 The MN Dupleix is hit on the deck

17:13 DKM Graf Spee is speckled with splinters from a near miss from MN Algerie (each french cruiser has a different burst color). All three boats not are steering evasively.

17:19 Double hit from the MN Algerie 203mm

17:21 one more hit from the MN Algerie, however a 280mm land on the MN Dupleix superstructure blowing off the airplanes and causing fire.

17:22 Another hit on the superstructure of MN Dupleix put out of service the main OFC unit.

17:24 MN Algerie land another 203mm shell on the DKM Graf Spee deck damaging the Arado floatplane catapulte.

17:25: DKM Graf Spee start to lay a smoke screen, MN Dupleix speed drop to 28 knots. The crew is battling the fire due to the floaplanes gazoline.

17:29 Coming out of the smoke screen on 260, the DKM Graf Spee open fire on the MN Algerie at a distance of 9500m

17:31 Major hit on the MN Algerie from a 280mm shell.

17:32 Another hit on the MN Algerie, second fore turret is out of action. The MN Dupleix score one 203mm hit on the DKM Graf Spee belt (distance 10km)

17:33 Another hit on the MN Algerie, major damage on the front, both 203mm turret are now out of action. MN Dupleix score another penetrating hit on the DKM Graf Spee broadside.

17:34 MN Algerie is crippled, down to 20knots max speed and brake off behind a smoke screen, MN Dupleix score another hit on the DKM Graf Spee damaging the OFC (distance 8000m). MN Dupleix brake off also behind the MN Algerie smoke screen. Due to waterline damages the DKM Graf Spee is now reducing the speed to 20 knots.

This a strategic victory for the allied as the Force X will be able to catch up the DKM Graf Spee shadowed by the 2 crippled CA.

Final Score:
DKM Gref Spee has some sections flooded., speed dropped to maximum 20 knots. The main OFC system is damaged. It will be an easier target to HMS Hermes string-bags. Allied narrow strategic victory as both French CA are badly crippled and will have to retire to Dakar. The statistic are:
DKM Graf Spee: 148 280mm shells fired, 18 hits
MN Algerie: 158 203mm shells fired, 11 hits
MN Dupleix : 173 203mm shells fired 13 hits
Note : near misses causing splintering damage are counted as hit

Even if the 2 CA are badly mauled, the consequences for them are not as bad. They will slowly go back to Dakar for repair. For the AGS it is different, there is no german base around! The consequences of the much lower damage are dramatic, most likely the AGS is condemned.
Attachments
iOS Simulator Screen shot Apr 6, 2015, 3.24.32 PM.png
(133.49 KiB) Not downloaded yet

User avatar
Dave Saxton
Supporter
Posts: 2876
Joined: Sat Nov 27, 2004 9:02 pm
Location: Rocky Mountains USA

Re: Graf Spee trying to escape back to Germany...

Postby Dave Saxton » Tue Apr 07, 2015 3:35 am

ric_roc wrote:Thanks for the feedbacks!
I discounted the Radar firing control for the AGS based on Eric Grove's book (page 12), in a nutshell the "Seetakt" a 60 cm FuMG38G was effective to 15 km with not a sufficient bearing accuracy, the stereoscopic rangefinder was superior in bright hi-visibility conditions (13 Dec 1939). The radar was reserved for night and poor visibility.


Grove is not correct about the range attainment. It was effective to at least 25km. That is based on primary documents data. Bearing accuracy without lobe switching is not a problem in conditions of good visibility because the radar range would be used in combination with optic bearing data in such conditions. The official documents for range accuracy of the optical range finders as tested on the panzerschiffs has been posted in these forums. It reads within 30 meters at 230hm range, which is amazing. Some people refuse to believe this, but that is what the document reads. In comparison large range finders of this type are usually considered to be at best accurate to 1% of the range. That would be 230 meters at 230hm, while the radar was accurate to within 100 meters at any range. Either way the range data available to AGS's firecontrol would have been significantly superior than its opponents.
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.

ric_roc
Junior Member
Posts: 14
Joined: Tue Mar 10, 2015 3:46 am

Re: Graf Spee trying to escape back to Germany...

Postby ric_roc » Tue Apr 07, 2015 3:39 am

For comparison I added top view of:
MN Algerie
DKM Graf Spee
HMS Exeter
That explain the staying power of the 2 French CA
Attachments
Comparison.png
Comparison.png (168.29 KiB) Viewed 621 times

ric_roc
Junior Member
Posts: 14
Joined: Tue Mar 10, 2015 3:46 am

Re: Graf Spee trying to escape back to Germany...

Postby ric_roc » Tue Apr 07, 2015 3:53 am

Dave,
thanks for the info on the german ORF, it is much better that what I have in the model and I will "upgrade" in my next release! It is not exactly a surprise due to the quality of the german optic industry.
Best regards,
Ric roc

alecsandros
Senior Member
Posts: 3990
Joined: Wed Oct 14, 2009 2:33 pm
Location: Bucharest, Romania
Contact:

Re: Graf Spee trying to escape back to Germany...

Postby alecsandros » Tue Apr 07, 2015 6:35 am

ric_roc wrote:Dave,
thanks for the info on the german ORF, it is much better that what I have in the model and I will "upgrade" in my next release! It is not exactly a surprise due to the quality of the german optic industry.
Best regards,
Ric roc

... During the retreat phase of battle for River Plate, Achilles was straddled 2 times from 23km by AGS, forcing the British cruiser to retreat to 25km.

As Harwood wrote: "3. The fire of the enemy’s 11 inch guns at a range of 13 miles was very accurate; this emphasises the necessity of zigzagging (speed permitting) to throw out the enemy’s ranged plot. A drastic alteration of course at the moment a salvo was fired was found to be desirable."

Steve Crandell
Senior Member
Posts: 630
Joined: Wed Feb 05, 2014 7:05 pm

Re: Graf Spee trying to escape back to Germany...

Postby Steve Crandell » Tue Apr 07, 2015 2:49 pm

I wouldn't think that at 26,000 yds a cruiser would be able to change course fast enough to make a difference, considering time of flight of 11" shells at that range and a several hundred yard salvo spread. It would also of course slow the cruiser quite a bit if using a lot of rudder, something that would seem necessary. Wouldn't it take 10 to 15 seconds or so to even apply full rudder?


Return to “Hypothetical Naval Scenarios”

Who is online

Users browsing this forum: No registered users and 1 guest