[Stiebler]

It's actually very easy to put a radar-warning-receiver (rwr) on the Type XXI.

This is because the Type XXI-FuMO391 radar was mounted by the devs on top of the schnorchel. All you have to do is change the type from 'radar' to 'rwr'.
In GWX2 the Type XXI *already* has this change made for you in the sensors.dat file (for the FuMO391 - sensor type is now 4 (= rwr), originally 1 (= radar).)

So to access this rwr earlier than in the mod, all you need to do is follow this procedure:
1. Make a copy of your GWX2 'LateWar Sensors' Mod in your mods folder. Rename it to something memorable, like 'Late_Sensors_TypeXXI'.
2. In the new folder, locate file submarine\NSS_Uboat21\NSS_Uboat21.sns (as Ref suggested), and change the starting date to whatever you want (year, month). Let us say to '19440101'.
3. Again, in the new folder locate file cfg\basic.cfg. Find [EQUIP 5] (radar-warning) near the bottom of the file and, in the same section, locate the entry 'IdX7=1279' (for the FuMO391). Change the values of 'Year7' and 'Month7' to a starting date just before the date you used in (2) above. Let us say Year7=1943, Month7=12. You might like also to change the 'Renown' to 0 (was 20000).
4. Now use JSGME to add your new mod 'Late_Sensors_TypeXXI' to your installation.

All should work fine now.

One final point:
You might wish to change the range of the rwr for the FuMO391 (the range in GWX2 in 9.5 km, which is far too long).
You can find the ranges in file data\library\sensors.sim. Change 'maxRange' and 'PreciseRange' for the FuMO391 to something like 5 km. Don't forget to make a copy of the original sensors.sim file first, and install it in your folder 'Late_Sensors_TypeXXI\data\library'.
[For the record, the *real* range of the schnorchel-mounted rwr was just *one* km! (for short-wavelength radar). That is why the schnorchels had tarnmatte added to them. But, for game purposes, 5 km is about realistic.]


Stiebler.