Gun precision / dispersion

[hans zurbriggen]

Hello Mr.Rico,
I stand corrected. I cannot find out nor remeber where I have read such info re. height of Bismarck class main rangefinder (40.5 meters).
You are correct, it should be around 32 meters and thus Tirpitz late radar antenna (6x3 meters) more or less from 34 to 37 meters (see https://www.kbismarck.org/forum/downloa ... hp?id=4120).
Thank you for correcting me.

Based on above, the maximum radar range, limited by horizon, should have been around 46 km against a similar ship. If TS60 ship-borne radar sets could detect ships at 60 km (https://www.kbismarck.org/forum/viewtop ... 368#p91368), it means refraction effect was heavily involved.

hans

[hans zurbriggen]

Hello Mr.fsimon,
reading back your posts, I noticed a sentence re. Sophie : "FuMO 31 "Sophie" with 400kW was cancelled in favor of "Hohentwiel" radar". Would you mind sharing your source about that ?
I think I have read that Sophie was on board Tirpitz by 1944, installed on a sponson on mast (antenna even visible here: https://www.kbismarck.org/forum/downloa ... hp?id=4120).

hans

[fsimon]

Hallo Hans,
page 169 in Fritz Trenkle: Die deutschen Funkmeßverfahren.
But that does not mean, that Tirpitz still could not have carried a test or prototype device. And Trenkle could also be wrong.
And the radar on Tirpitz' mast...could it be a Hohentwiel?
Best regards
Frank

[Thorsten Wahl]

This is the achieved detection range versus BB of the Funkmess ofGneisenau early 1941.

Screenshot 2022-07-13 135845.jpg (22.38 KiB) Viewed 9806 times

The gun laying Funkmess for battery "Grosser Kurfurst"
Could provide a firing solution up to at least until 33,6 km.

6067558_c2b1a4b59a77625635e7eb1924efa8cf_p.jpg (46.06 KiB) Viewed 9802 times

Another report indicates that Zielbeobachtungsschießen(ZB Schießen)was impossible due to electronic countermeasures/ interference , wich the "Brits" started circa spring 1941.

ZB Schießen includes spotting fall of shot.
Cap Nez gunlaying Funkmess equipment was at this time a Fumo 2 Calais B. Later replaced by a Würzburg Riese.



Spotting range of shell impacts same timframe(Gneis early 1941)
[

Screenshot 2022-07-13 145231.jpg (32.6 KiB) Viewed 9806 times

After about this time, basically all basic research into technology, that was expected not promising in the short term, was suspended by order of the Führer...Until they recognised they lay back...Sometime in 1943.


The Allies used the time "given for free" to them.

Regarding Hohentwiel: H was a fairly "primitive" and lightweight set only usable for tactical purposes. But it has very small size of antenna despite giving sufficent range. So the "true" gunlaying funkmess sets could be freed from tactical use.

[hans zurbriggen]

Hello Mr. fsimon,
antenna visible (https://www.kbismarck.org/forum/downloa ... hp?id=4120) on Tirpitz mast looks like a 'Palau'.
Hohentwiel radar often used Palau antenna. Did Sophie use same antenna too ?

hans

[Dave Saxton]

This is the achieved detection range versus BB of the Funkmess ofGneisenau early 1941.
Screenshot 2022-07-13 135845.jpg


The gun laying Funkmess for battery "Grosser Kurfurst"
Could provide a firing solution up to at least until 33,6 km.
6067558_c2b1a4b59a77625635e7eb1924efa8cf_p.jpg
Another report indicates that Zielbeobachtungsschießen(ZB Schießen)was impossible due to electronic countermeasures/ interference , wich the "Brits" started circa spring 1941.

ZB Schießen includes spotting fall of shot.
Cap Nez gunlaying Funkmess equipment was at this time a Fumo 2 Calais B. Later replaced by a Würzburg Riese.



Spotting range of shell impacts same timframe(Gneis early 1941)
[Screenshot 2022-07-13 145231.jpg

After about this time, basically all basic research into technology, that was expected not promising in the short term, was suspended by order of the Führer...Until they recognised they lay back...Sometime in 1943.


The Allies used the time "given for free" to them.

Regarding Hohentwiel: H was a fairly "primitive" and lightweight set only usable for tactical purposes. But it has very small size of antenna despite giving sufficent range. So the "true" gunlaying funkmess sets could be freed from tactical use.

S&G retained the early FuMG39 versions of Seetakt until after their arrival at Brest. This model had a power output of 2 kw using TS1 triodes.

At the time of the Channel Dash the radars had been replaced by the FuMG40 versions. These used the TS6 triodes giving 8 kw output. This gave about 20% boost in range performance. Later developments of FuGM40 included larger antennas operating common mode which gave a further boost of about 30% in range performance.

I agree, Hohentwiel was a very simple design not capable of fine precision or resolution. But the power output by using anode modulation was 50 kw. With a 2 ms pulse width the illumination energy was 100 kw. But otherwise H did not compare well to contemporary GEMA sets.

By 1943 GEMA ship board fire control sets featured:

Phase coherant operation.
Phased array scanning antennas.
Lobe on Receive Only operation.
Commom mode operation.
Fine range and bearing accuracy.
Fine range and bearing resolution.
Frequency agility (over a narrow band)
Range performance well exceeding 30 km.

(many of the above features were available from May 1940.)

Late war, a strictly tactical GEMA set, code named Sophie, came avialable which offered far better performance to Hohentwiel using the same size anttena. Sophie featured:

400 kw using spark gap modulated TS60 triodes.
800 Kw illumination energy.
New high resolution signal processing and presentation modules code named Paris II
Frequency agility over a wide band.

[fsimon]

Good to see you again, Mr Saxton, Dave, if I may.
Do you know, if the 2x6m vertical polarized antenna of the FuMG 40 / FuMO 26 used common mode like the large 3x6m horizontal polarized antenna?
How did the ship borne control radars make use of the electronical scan? Was the electronical scan only used in elevation to measure aircraft, i.e on the FuMO 26 on Prinz Eugen using the "owl ears" and on the large 3x6m system? Or could it also be used in azimuth for spotting the fall of shot?
If so, what kind of display was used for that?
So many questions...I am sorry

Best regards
Frank

[fsimon]

With the inputs of Hans and Thorsten I made some updates to the Fire Control Radar summary:

GE early 1.JPG (133.38 KiB) Viewed 9726 times

GE early 2.JPG (100.58 KiB) Viewed 9726 times

[fsimon]

Late war FCR:

GE late 1.JPG (113.93 KiB) Viewed 9726 times

GE late 2.JPG (71.99 KiB) Viewed 9726 times

Notes GE late.JPG (32.53 KiB) Viewed 9726 times

[Thorsten Wahl]

PG range versus Destroyer 1944 with Funkmess
This could be the Fumo 81 Berlin set.

the "owl ears" on the large 3x6m system" indicate the presence of the Fumo 81 Berlin Set as Berlin had air search capabilities including measuring target height.

Fumo Performance PG vs destroyer.jpg (37.95 KiB) Viewed 9713 times

[dunmunro]

Radar in a Town class cruiser - 1943-44:

https://youtu.be/t-fJ255jMH4

[Dave Saxton]

The Berlin antenna was plastic "polyrods" or "fingers" spinning around on a horizontal plate, inside a radome.* The presentation was on a PPI.

I'm pretty sure "owls ears" refers to the FuMO26 module PB for vertical, but I could be wrong.

*Note: Mk8 also used polyrods.

[Dave Saxton]

Good to see you again, Mr Saxton, Dave, if I may.
Do you know, if the 2x6m vertical polarized antenna of the FuMG 40 / FuMO 26 used common mode like the large 3x6m horizontal polarized antenna?
How did the ship borne control radars make use of the electronical scan? Was the electronical scan only used in elevation to measure aircraft, i.e on the FuMO 26 on Prinz Eugen using the "owl ears" and on the large 3x6m system? Or could it also be used in azimuth for spotting the fall of shot?
If so, what kind of display was used for that?
So many questions...I am sorry

Best regards
Frank

As far as I know the earlier installation on PG (actually called Flakleit-G) was not common mode.

The signal was measured by phase across the receiving antenna. The minunum signal was presented at the center on a CRT. The stronger signal strength was presented on the screen to left and right of center. As long as the signal presented to the left and right on the screen matched, then the antenna was pointed directly at the target to an accruracy to within 0.10 degrees. In the case of the fall of shot, if the splashes were left or right of the target it would cause a larger presentation on the left or right on the screen.

In the case of Flakleit-G, additional send and receive antennas were installed so target height could be measured. Additional presentation modules were just added for the vertical. Once common mode came into use, it was no longer required to add additional receiving and transmitting arrays for vertical. It could be done using existing dipoles. The 6x3 meter antenna had 64 dipoles.

The technology was available by 1940 and was used on the new model FuMG40 (ie..FuMO 26/27) sets. If the older sets FuMG39 (ie..FuMO23 and so forth) employed lobe switching it was a totally different method called peil verfaren A/N.

Bismarck was equipped with the phased array technology as indicated in AKVS trials reports, indicating Bismarck had blind fire capability and the newer model radars.

[fsimon]

Thank you for your replies, Thorsten and Dave!
Here are the "owl ears" on Prinz Eugen. 2x4m antenna plus the side attachmets for elevation.

PE owl ears 1.JPG (51.71 KiB) Viewed 9651 times

PE owl ears 2.JPG (55.61 KiB) Viewed 9651 times

[fsimon]

I understand, that the earlier 2x4m antenna was not common mode. I understand that the 3x6m antenna was common mode and horizontaly polarized. I was wondering about the 2 x 6m antenna on Scharnhorst's aft mount and Scheer and Lützow, since the 2x6m antenna appeared at around the same time as the large 3x6m antenna.
Best regards
Frank