XP-82/P-82B vs P-82C/D DF loop placement

[BarnOwlLover]

On the XP-82 and P-82B, what appears to be the DF loop is mounted on the rear fuselage opposite the main aerial. But on the C/D night fighter R&D aircraft, the DF loop was moved to inside the cockpit behind the pilot's seat. Was this due to equipment added for the night fighter/radar conversion, or some other factor?

 

[GrauGeist]

RFI would be a factor in relocation.

 

[MIflyer]

There was a change in the ADF equipment. The earlier models would have had the loop antenna either by itself or in a football fairing and it was not Automatic direction finding but .required the loop to be rotated manually. They could not put the loop inside the canopy because the primary mission was very long range escort and the airplanes featured the ability to fold back the seat headrest armor and let the pilot, fold back the rudder pedals, recline and take a snooze.

The full production models, the E, F, G went to the ARN-6, which used a different type antenna, similar to the ones used by the Germans, which was a dome sometimes mistaken for a light by the uninformed and also seen inside the canopy on F-86, F-94 and B-47. The ARN-6 was pretty much the standard USAF ADF and remained in service well into the 1970's.

 

[BarnOwlLover]

I'm wondering if those were used on RCAF P-51s post war?

 

[MIflyer]

I'm wondering if those were used on RCAF P-51s post war?

What, ARN-6 or DF loops? I can recall seeing what must have been an ADF antenna fairing on RCAF Harvards after WWII, but I don't know what equipment was used.

 

[BarnOwlLover]

I've seen the ARN-6 type device on the A-26 with a similar fairing. Some RCAF P-51s also had some device with a similar fairing, though most I've seen had normal antenna and no DF loops (though some existed?).

As to the F-82, the P-82C/D (radar-equipped P-82Bs) did have the DF loop behind the pilot's seat. And I don't think be it DF loop or ARN-6, that the pilot's head armor can be dropped back with either piece behind the seat.

But I do wonder if equipment changes lead to the DF loop relocation, as the C/D sprouted several antenna/aerials in addition to the radar pod.

 

[ThomasP]

I know the RCAF used the ARN-6 equipment post-war, but I do not know for how long or how common it was.

Here is a photo of a RCAF Mustang Mk IV with the ARN-6 antenna under the canopy behind the pilot. Note that the aft section of the bubble canopy is of a different shape than the 'standard' one for the Mustang Mk IV/F-51D.

RCAF photo

PS I think the ARN-6 is mentioned in one or more of the RCAF Mustang pilot's manuals.

 

[MIflyer]

Note that the aft section of the bubble canopy is of a different shape than the 'standard' one for the Mustang Mk IV/F-51D.

Very interesting! You know, the Dallas plant used some canopies that bulged out more than the ones used in Inglewood,

 

[ThomasP]

I wonder if this type of equipment was the reason they did so, or if there was some other purpose.

 

[MIflyer]

I wonder if this type of equipment was the reason they did so, or if there was some other purpose.

I suspect it was just because they got a different manufacturer for the canopy but I don't know. That ARN-6 antenna does need to be under an RF transparent cover; in the F-80 it was under that squared off black area on the upper nose. Note that RCAF Mustang has both the AN-104 VHF antenna and a long wire antenna, but the ARN-6 needs a "sense" antenna, a non-directional antenna that can be used to compare with the directional antenna, and that is probably what the long wire is for, as well as enabling reception of voice modulated signals for weather info and control tower communications.

I think the canopy difference is just like the prop being different; Dallas built as many K models with Aeroproducts props as they did D's with Ham Standard props. Squadron even used to sell "Dallas style" model kit canopies.