by Tommy H. Thomason

Tuesday, March 24, 2020

Lockheed P2V-5 vs -7 Neptune

Hasegawa occasionally releases their 1/72 P2V-7 (P-2H) Neptune kit (it was also sold under the Revell brand). There were more than seven notably different configurations of the Neptune but one of the most popular besides the -7 was the -5. It was produced with at least three different noses and three different aft fuselages (defensive armament, MAD installation, and sensor dispenser) and certainly the most colorful paint schemes not to mention its civil use as a fire bomber. Note that the OP-2E was a modification of the -5 and the AP-2H was a modification of the -7.

For the P2V-7 bow turret and the tail-gun installation on earlier P2Vs, see http://tailhooktopics.blogspot.com/2016/02/early-p2vs.html

One -5 configuration closely resembles the -7 but there are exterior differences. The most obvious is the enlarged canopy of the -7.
The need for a longer bomb bay resulted in the big radome being moved four feet forward. This required relocating the nose-landing-gear wheel-well forward and shortening it, in part by lowering the pivot point of landing gear for retraction (the shock strut travel also appears to have been reduced).
Note that I have been unable to find an accurate length of the P2V-5 with the observer nose. What is shown is at Fuselage Station 0 based on scaling photographs taken from the side at a distance to minimize distortion.

As part of the -7 redesign, Lockheed relocated the engine controls, which had been on a pedestal between the pilots, to the forward end of the overhead console. That required bulging the canopy upward. Another major change was adding a large radar repeater screen and overlaid plotting board to the center of the instrument panel. I'm not sure why the cockpit was moved forward a few inches.

 Note that the P2V-3 inboard profile included above should be very similar to the P2V-5's, which I do not have.
There were three different canopies.

The P2V-5 (P-2E) canopy was bulged laterally, the overhead hatch was enlarged, and the two small side windows were changed to one large window and a narrow oval one.

The overhead hatches appear to have been slightly bulged upwards as well.
Igor Kolokolov

One unusual feature of the later P2Vs (-5 through -7) is the asymmetric engine cooling/exhaust configuration. The right side of the nacelle was configured with one exhaust stack and two cowl flaps; the left side, with two exhaust stacks and one cowl flap.
The Hasegawa kit instructions are quite clear in this regard and need to be followed to the part-number letter, literally.

My build notes (for a P2V-3C) state that the cockpit floor provided in the kit should be placed under the locating pegs rather than on top of them. This was confirmed in another modeler's build review.

The main error with the kit involves the landing gear. First, the sit. As built, the model does not have the correct nose-up "sit". I think the main landing gear is possibly too long. Larry Templeton wrote that he had to increase the height of the nose landing gear strut by 1/8 inch to get it right.

Not quite as obvious but not too difficult to fix are the width and offset of the nose landing gear wheel well and location of the main landing gear laterally in its wheel well. This holds for all P2V dash numbers.

The upper part of the nose gear strut and the nose wheel itself are located on the center line of the airplane. However, the lateral strength of the strut is partly provided by a brace that extends to the right side of the strut. Only one side of the strut is braced in this case because the left side of the fuselage below the cockpit floor is dedicated to a tunnel leading forward to the compartment in the nose. As a result, the well is offset to the right. Up through the P2V-6, the nose wheel well extended 12 inches to the left and 24 inches to the right for a total of 36 inches. On a pretty good Lockheed P2V-7 drawing, it extends 12 inches to the left and only 18 inches to the right for a total of 30 inches. In both cases, the gear doors appear to be the same width, i.e. 18 inches on P2V-1 through -6 and 15 inches on the P2V-7.

                       Igor Kolokolov                                                  Bill Spidle             

Note the different distance between the right side of the wheel well and the lateral brace (1) as a result of the narrowing of the wheel well in the -7, the difference in the shape of the lower section of the nose gear strut (2), and the different location of the nose gear steering piston (3).

The Hasegawa kit has the main landing gear mislocated in its wheel well. The strut needs to be relocated inboard so the center of the distance between the outside of the strut and the outside of the wheel is on the center line of the nacelle.
The main landing gear strut and the side brace attached to it are mounted on the aft side of the bottom of the wing torque box. The "Y" retraction strut is not symmetrical as it is in the kit but displaced inboard and mounted on the front side of the bottom of the wing torque box. The wheel, when retracted, is located between the front of the wing torque box and the engine firewall.

Note, this is a P2V-3 main landing gear wheel well; the P2V-7's is different. See the links below for pictures of the -5 and -7 nacelle interiors.

One less notable error in the Hasagawa kit is the missing "kink" in the aft fuselage that was introduced with the production P2V-1s. In effect, the empennage was rotated 2° downwards at fuselage station 764.4, which was about half way between the leading edges of the vertical fin and the horizontal stabilizer as shown on this Lockheed P2V-7 drawing.
The omission of the kink is masked by the presence of the radome on the bottom of the fuselage. My guess is that this was done as the simplest way to increase the incidence of the horizontal stabilizer.

With respect to the horizontal stabilizer itself, the elevator appears to be very large relative to the stabilizer. The elevator is in fact represented by a less prominent panel line aft of what would be taken to be the leading edge of the elevator. Lockheed incorporated a variable-camber stabilizer to provide the smallest possible horizontal for the stability and pitch control requirements.
Aviation Week, 25 July 1949

There are at least two basic conversions of the Hasegawa kit to the -5: Falcon Triple Conversion VII and BlackBird Models. The former is vac formed and provides the bow and tail turrets; the latter is resin and comes in at least two versions: BMA 72029 Neptune MR.1 and BMA 72032 OP-2E.
Note that RedRoo distributes BMA 72029 with RAAF decals.
Although not in stock at the moment, their website is https://www.redroomodels.com/. They're easy to work with so take a look at their site and leave them a note to let you know when they have one available.

Hannants currently lists BMA72032 as not in stock but they do take back orders for it; decals are separate: they have Blackbird BMD041 P2V-5 decals for VP-2 and VP-5 and BMD048 decal for a Argentine P2V-5 in stock but don't currently list the requisite BMA 72029. See https://www.hannants.co.uk/.

The Falcon conversion can be found with a Google search.

Click HERE for an OP-2E build review on Britmodeler

Click HERE for an ambitious P2V-7 build on Britmodeler. 

Click HERE for details on the inside of the P2V-7 engine nacelle.

Click HERE for excellent walkarounds of a P2V-5 and P2V-7 configured as "Borate Bombers" that show some of the differences and details.









4 comments:

  1. Thats a very useful post. Thank you.

    Martin

    ReplyDelete
  2. Again, Tommy, an extremely useful post. Thank you.

    Martin

    ReplyDelete
  3. Tommy, is it true you are working on a Ginter Naval Fighters book on the Neptune?

    ReplyDelete
    Replies
    1. No, I'm working on a redo of the Naval Fighters F7U-3 monograph. It will be my last one, but then the F4H-1 monograph was also going to be my last one. I do plan to do a detailed post on the P2V-3C some day.

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