B-25 weapons thread

MiTasol · Nov 19, 2025

CATCH 22 said:
The 2 loop antennae are seen on some of those general-transports (check B-25 gen. Arnold or gen. Eisenhower). I do believe the second one is a back-up (double radio compass).

It is possible, considering the persons carried, that the two antennas were to allow the nav to triangulate the aircraft's position "instantly" rather than by taking one bearing then hunting for and finding a second known signal source given that the ADFs of the day required hand tuning the receivers.

CATCH 22 · Nov 19, 2025

MiTasol said:
It is possible, considering the persons carried, that the two antennas were to allow the nav to triangulate the aircraft's position "instantly" rather than by taking one bearing then hunting for and finding a second known signal source given that the ADFs of the day required hand tuning the receivers.

Quite possible in the case with the weather-plane - the both antennae are mounted with a distance one from another.
On the general's planes they were always together, under the nose. I think I read somewhere about doubling some of the systems on those important a/c. Below is the first B-25 of gen. Arnold (the one that still flies) - compare with the photo of the weather-plane. BTW don't know the purpose of the ring-antenna on top of the nose.

GrauGeist · Nov 19, 2025

CATCH 22 said:
BTW don't know the purpose of the ring-antenna on top of the nose.

The ring or "null loop" antenna was used for direction finding.

Greg Boeser · Nov 20, 2025

GrauGeist said:
The ring or "null loop" antenna was used for direction finding.

The Doughnut of Death.

MiTasol · Nov 20, 2025

GrauGeist said:
The ring or "null loop" antenna was used for direction finding.

And was usually part of an earlier type DF system. Three DFs on one aircraft appears an overkill but it may well be that the ring type was more sensitive on certain frequencies.

CATCH 22 · Nov 20, 2025

MiTasol said:
And was usually part of an earlier type DF system. Three DFs on one aircraft appears an overkill but it may well be that the ring type was more sensitive on certain frequencies.

I too think that this is an overkill. Maybe in this case the top loop antenna and one of the radio-compass DF-antennae was used for that instant location of the position, you mentioned before? The same configuration was seen on the very first B-25 s/n 40--2165 modified for company needs (transport, tests) by NAA:

Gen. Arnold's plane s/n 40-2168 was later used as a transport for other high ranking officers and then sold to the private market. The late nose-antenna was different:

GrauGeist · Nov 20, 2025

The "ring" antenna was extremely sensitive to weak radio signals, capable of fine adjustment to get a "fix" on the source.

Virtually all maritime/scout aircraft in the 1930's were equipped with the null loop direction finding equipment as well civil airliners, especially long distance types.

MiTasol · Nov 22, 2025

A new site - to me anyway.

B-25 History Project

B-25 Mitchell bomber history

b-25history.org

CATCH 22 · Nov 22, 2025

MiTasol said:
A new site - to me anyway.

B-25 History Project

B-25 Mitchell bomber history

b-25history.org

Since 2014. It is pretty good. I think they add some new details from time to time so it's worth checking the site periodically. Some very good photos from the "biography" of each B-25 they describe.

B-25 weapons thread

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MiTasol

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CATCH 22

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Generalfeldmarschall zur Luftschiff Abteilung

Greg Boeser

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MiTasol

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CATCH 22

Tech Sergeant

GrauGeist

Generalfeldmarschall zur Luftschiff Abteilung

MiTasol

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B-25 History Project

CATCH 22

Tech Sergeant

B-25 History Project

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