P-51-1 Radios Accurate Miniatures Got Them Wrong

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MIflyer

2nd Lieutenant
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9,394
May 30, 2011
Cape Canaveral
Accurate Miniatures brought out a series of 1/48 models of the Allison Mustangs, including the Mustang Mk Ia, the P-51-1, the P-51A, and the A-36A. These are very fine kits and are head and shoulders above kits such as the 1/48 Monogram P-51B. Accurate Miniatures are to be commended in attempting to get the radio equipment depicted in these kits correct, but they did not quite get there, producing a rather odd combination of features.

Osprey Modeling Manual No. 19, "North American P-15 Mustang" shows details of a superb build of an Accurate Miniatures P-51-1, but further compounded the flaws in the kit by making up some additional incorrect details out of thin air.

The AM P-51-1, A-36A, and P-51A kits (all I have, but then again I have a total of 18 of them) all attempt to depict the SCR-274-N radio installation. SCR-274-N is an LF receive and HF transmit/receive installation that features separate receivers and transmitters for each band. Typically, there were three receivers and two transmitters, although it was pretty easy for units to change that arrangement as required. Different frequency transmitters and receivers could be swapped out very easily. When they arrived in the CBI the Air Commandos found their P-51A's offered an advantage over other fighters in the theater since they could be fitted with radios that enabled them to talk directly to the ground troops they were supporting, an idea that sounds utterly logical from today's viewpoint but was all but radical for that stage of WWII.

Here is a page from the P-51A maintenance manual, showing the SCR-274-N installation. The three receivers were down low behind the pilot's seat while the two transmitters were up above. It seems likely you could not even see the three receivers without dismantling something but the two transmitters were quite obvious though the rear side windows.

P-51A-274N-110.jpg


Here is a shot of three receivers being installed in a P-51A at the NAA factory. The receivers as well as the transmitters were mounted on racks which were hard to see easily, basically covering the bottoms of the radios. The wiring was at the rear bottom of the racks and thus was al but invisible.

274in51A.jpg


Here is a shot of one receiver and one transmitter. The receivers had drum-shaped objects clipped to the rear top; those are dynamotors that serve as power supplies, converting the 28VDC of the aircraft to 250 VDC, The transmitter dynamotors were located separately, along with the modulator that enabled AM transmissions.

DSCF4198.JPG
DSCF4202.JPG

Now, here is picture from the Osprey book. What AM did was supply kind of a weird combination of transmitters and receivers. The "radio rack" has not two but three pieces of equipment that look like transmitters but have depictions of dynamotors at the rear such as receivers actually have. Then the Osprey folks added some wiring on the top rear of the transmitters, which provides excellent but inaccurate detail. The actual airing harnesses for the SCR-274-N sets were at the bottom rear of the transmitters and receivers and I doubt you could see them in 1/48 scale. What you could see was the antenna wire, which would have been white and extended from the antenna connections of the receivers and transmitters over and up to that square box mounted behind the pilot;s seat, which was the RF meter.
P-51-1RAdios.jpg

So, if you want a more accurate Accurate Mustang, take that radio rack they provide, cut off one of the transmitters and all three of the humps in the back and fill in the resultant holes accordingly. If you have two sets of those radio racks and want to depict the receivers down below, cut off the front of those three transmitters to make them shorter, fill in the holes, and paint dials on at the top of the front face of the receivers.

Good luck!
 
Accurate Miniatures brought out a series of 1/48 models of the Allison Mustangs, including the Mustang Mk Ia, the P-51-1, the P-51A, and the A-36A. These are very fine kits and are head and shoulders above kits such as the 1/48 Monogram P-51B. Accurate Miniatures are to be commended in attempting to get the radio equipment depicted in these kits correct, but they did not quite get there, producing a rather odd combination of features.

Osprey Modeling Manual No. 19, "North American P-15 Mustang" shows details of a superb build of an Accurate Miniatures P-51-1, but further compounded the flaws in the kit by making up some additional incorrect details out of thin air.

The AM P-51-1, A-36A, and P-51A kits (all I have, but then again I have a total of 18 of them) all attempt to depict the SCR-274-N radio installation. SCR-274-N is an LF receive and HF transmit/receive installation that features separate receivers and transmitters for each band. Typically, there were three receivers and two transmitters, although it was pretty easy for units to change that arrangement as required. Different frequency transmitters and receivers could be swapped out very easily. When they arrived in the CBI the Air Commandos found their P-51A's offered an advantage over other fighters in the theater since they could be fitted with radios that enabled them to talk directly to the ground troops they were supporting, an idea that sounds utterly logical from today's viewpoint but was all but radical for that stage of WWII.

Here is a page from the P-51A maintenance manual, showing the SCR-274-N installation. The three receivers were down low behind the pilot's seat while the two transmitters were up above. It seems likely you could not even see the three receivers without dismantling something but the two transmitters were quite obvious though the rear side windows.

View attachment 721244

Here is a shot of three receivers being installed in a P-51A at the NAA factory. The receivers as well as the transmitters were mounted on racks which were hard to see easily, basically covering the bottoms of the radios. The wiring was at the rear bottom of the racks and thus was al but invisible.

View attachment 721243

Here is a shot of one receiver and one transmitter. The receivers had drum-shaped objects clipped to the rear top; those are dynamotors that serve as power supplies, converting the 28VDC of the aircraft to 250 VDC, The transmitter dynamotors were located separately, along with the modulator that enabled AM transmissions.

View attachment 721241View attachment 721242
Now, here is picture from the Osprey book. What AM did was supply kind of a weird combination of transmitters and receivers. The "radio rack" has not two but three pieces of equipment that look like transmitters but have depictions of dynamotors at the rear such as receivers actually have. Then the Osprey folks added some wiring on the top rear of the transmitters, which provides excellent but inaccurate detail. The actual airing harnesses for the SCR-274-N sets were at the bottom rear of the transmitters and receivers and I doubt you could see them in 1/48 scale. What you could see was the antenna wire, which would have been white and extended from the antenna connections of the receivers and transmitters over and up to that square box mounted behind the pilot;s seat, which was the RF meter.
View attachment 721245
So, if you want a more accurate Accurate Mustang, take that radio rack they provide, cut off one of the transmitters and all three of the humps in the back and fill in the resultant holes accordingly. If you have two sets of those radio racks and want to depict the receivers down below, cut off the front of those three transmitters to make them shorter, fill in the holes, and paint dials on at the top of the front face of the receivers.

Good luck!
Excellent article, I just noticed this one. Great information. Just another thought, the Tamiya P-38J and F/G kits both have nicely detailed SCR-274N sets, if you are doing an aircraft with SCR-522 (any in Europe or Pacific in 1944 or later) then you have some beautiful SCR-274Ns to put in the P-51.
Dave
 
Accurate Miniatures brought out a series of 1/48 models of the Allison Mustangs, including the Mustang Mk Ia, the P-51-1, the P-51A, and the A-36A. These are very fine kits and are head and shoulders above kits such as the 1/48 Monogram P-51B. Accurate Miniatures are to be commended in attempting to get the radio equipment depicted in these kits correct, but they did not quite get there, producing a rather odd combination of features.

Osprey Modeling Manual No. 19, "North American P-15 Mustang" shows details of a superb build of an Accurate Miniatures P-51-1, but further compounded the flaws in the kit by making up some additional incorrect details out of thin air.

The AM P-51-1, A-36A, and P-51A kits (all I have, but then again I have a total of 18 of them) all attempt to depict the SCR-274-N radio installation. SCR-274-N is an LF receive and HF transmit/receive installation that features separate receivers and transmitters for each band. Typically, there were three receivers and two transmitters, although it was pretty easy for units to change that arrangement as required. Different frequency transmitters and receivers could be swapped out very easily. When they arrived in the CBI the Air Commandos found their P-51A's offered an advantage over other fighters in the theater since they could be fitted with radios that enabled them to talk directly to the ground troops they were supporting, an idea that sounds utterly logical from today's viewpoint but was all but radical for that stage of WWII.

Here is a page from the P-51A maintenance manual, showing the SCR-274-N installation. The three receivers were down low behind the pilot's seat while the two transmitters were up above. It seems likely you could not even see the three receivers without dismantling something but the two transmitters were quite obvious though the rear side windows.

View attachment 721244

Here is a shot of three receivers being installed in a P-51A at the NAA factory. The receivers as well as the transmitters were mounted on racks which were hard to see easily, basically covering the bottoms of the radios. The wiring was at the rear bottom of the racks and thus was al but invisible.

View attachment 721243

Here is a shot of one receiver and one transmitter. The receivers had drum-shaped objects clipped to the rear top; those are dynamotors that serve as power supplies, converting the 28VDC of the aircraft to 250 VDC, The transmitter dynamotors were located separately, along with the modulator that enabled AM transmissions.

View attachment 721241View attachment 721242
Now, here is picture from the Osprey book. What AM did was supply kind of a weird combination of transmitters and receivers. The "radio rack" has not two but three pieces of equipment that look like transmitters but have depictions of dynamotors at the rear such as receivers actually have. Then the Osprey folks added some wiring on the top rear of the transmitters, which provides excellent but inaccurate detail. The actual airing harnesses for the SCR-274-N sets were at the bottom rear of the transmitters and receivers and I doubt you could see them in 1/48 scale. What you could see was the antenna wire, which would have been white and extended from the antenna connections of the receivers and transmitters over and up to that square box mounted behind the pilot;s seat, which was the RF meter.
View attachment 721245
So, if you want a more accurate Accurate Mustang, take that radio rack they provide, cut off one of the transmitters and all three of the humps in the back and fill in the resultant holes accordingly. If you have two sets of those radio racks and want to depict the receivers down below, cut off the front of those three transmitters to make them shorter, fill in the holes, and paint dials on at the top of the front face of the receivers.

Good luck!
There are a couple of things to note about that photo of a transmitter & receiver. First, the receiver front panel has been modified; a common conversion for amateur radio use post-war. Second, the receiver appears to be actually an ARC-5 with an SCR-274N top cover. Most ARC-5s has a black crackle finish while the SCR-274Ns were bare aluminum.
 
The predecessors to the ARC-5's, Navy radios built prior to Pearl Harbor, were black wrinkle. There was some mixing of black wrinkle and bare aluminum radios. For the receivers, the Pre-ARC-5 Navy radios, SCR-274-N and ARC-5's were interchangable. For the transmitters the ARC-5's had differences from the others and were not interchangable. Note that in the photo of the SCR-274-N being installed in the P-51A one of the receivers has a black wrinkle adapter even though the set is bare aluminum. And I have only seen bare aluminum VHF ARC-5 receivers and transmitters, which were very different in both appearance and electronics from the others.

Yes, that particular receiver has been modified with a phone jack and the installation of controls in the front panel adapter. It is easy to take an adapter and mount the controls and phone jack in it, leaving the rest of the set original, but relatively few people went to that much trouble and it was not unusual for them to rip the whole adapter mount out of the radio, for no obvious reason.

"Just another thought, the Tamiya P-38J and F/G kits both have nicely detailed SCR-274N sets,"

Well, that is interesting! The Monogram 1/48 B-17G has some SCR-274-N sets inside, where you can't see them and the Monogram 1/48 B-26C has some mounted on the back of the nose compartment. We know from the excellent photos that the 5000th P-38 Yippeee came off the production line with SCR-274-N but I have not opened the box of my 1/48 Minicraft kit of that airplane to see if they were faithfully reproduced.
 
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The predecessors to the ARC-5's, Navy radios built prior to Pearl Harbor, were black wrinkle. There was some mixing of black wrinkle and bare aluminum radios. For the receivers, the Pre-ARC-5 Navy radios, SCR-274-N and ARC-5's were interchangable. For the transmitters the ARC-5's had differences from the others and were not interchangable. Note that in the photo of the SCR-274-N being installed in the P-51A one of the receivers has a black wrinkle adapter even though the set is bare aluminum. And I have only seen bare aluminum VHF ARC-5 receivers and transmitters, which were very different in both appearance and electronics from the others.

Yes, that particular receiver has been modified with a phone jack and the installation of controls in the front panel adapter. It is easy to take an adapter and mount the controls and phone jack in it, leaving the rest of the set original, but relatively few people went to that much trouble and it was not unusual for them to rip the whole adapter mount out of the radio, for no obvious reason.

"Just another thought, the Tamiya P-38J and F/G kits both have nicely detailed SCR-274N sets,"

Well, that is interesting! The Monogram 1/48 B-17G has some SCR-274-N sets inside, where you can't see them and the Monogram 1/48 B-26C has some mounted on the back of the nose compartment. We know from the excellent photos that the 5000th P-38 Yippeee came off the production line with SCR-274-N but I have not opened the box of my 1/48 Minicraft kit of that airplane to see if they were faithfully reproduced.
The main circuit differences between the ARC-5 & SCR-274N transmitters were their tank circuits. One was series-fed while the other was parallel-fed. The ARC-5 & SCR-274N series of transmitters & receivers were a real milestone in communications technology. Compare thse Western Electric designs with the old GE- designed boat anchor BC-375!
When I received my Novice license in 1953, I was living in Newport, RI and New England was a hotbed of VHF activity so I used an SCR-522 as an AM transmitter on 2M. Later, I moved to WV an used a BC459 on 40M CW.
 

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