Tailhook Topics

by Tommy H. Thomason

Thursday, November 26, 2020

Douglas A-4 Skyhawk: Early ECM Antennas

Defensive Electronic Countermeasures (DECM) against Surface-to-Air Missiles (SAMs) was a given for large Navy attack airplanes but not initially for the A-4 Skyhawk because of the size and weight of the electronics required. Losses over North Vietnam dictated its addition.

The exterior change was the addition of five antennas, three forward and two aft. One forward or one aft detected the radar pulse of four different kinds of fire-control radar. The ALQ-51 electronics then automatically transmitted a pulse from the other two forward antennas or the other one aft that misled the radar operator or confused him as to the location of the airplane, preventing guidance of the SAM to it. For an instructive video on the process, click HERE.

The antenna resembled a snow cone:

The forward transmitting antennas were located on either side of the nose landing gear actuator well. Two were probably required because there was no place to mount one aft of that or if there was, the airframe or stores might block the signal from it.

The antennas were exposed and therefore sometimes broken off. In that event or if they were not required, they would be replaced by a half-round black rubber ball as in the mount labeled 9 here:

A subsequent addition to the Skyhawk's ECM suite provided the pilot with a warning that a fire-control radar was tracking him to improve his chances of spotting a SAM fired at him and evading it in case it wasn't being spoofed. This was the APR-25. It utilized four antennas about the size and shape of small drink coasters, two facing forward and two aft. They were angled outward so the APR-25 electronics could analyze the strength of the pulse being received at each antenna, determine the direction it was coming from, and display that to the pilot on a scope in the cockpit.

The two aft antennas were mounted one on each side of the sugar scoop.

The two forward APR-25 antennas were colocated with the forward facing ALQ-51 receiving antenna in a larger fairing.

Thanks to Dave Dollarhide, Bill Egen, Carlton Floyd, and Jim Winchester for their help with this topic; any errors in the above were made by me. Comments, corrections, and additional information are welcome.






Monday, August 31, 2020

The Colorful TBM-3U

2 September 2020: Sword plans to issue a kit of the TBM-3U at the end of the year.

2 September 2020: The white store under the right wing is an AN/APS-4 radar. See https://tailspintopics.blogspot.com/2014/11/things-under-wings-anaps-4.html

Sword Models (https://www.facebook.com/swordmodels/) has just released three 1/72 scale kits of postwar TBMs (for a summary of all the U.S. Navy variants and a guideline for the presence of an internal or external tailhook, see https://thanlont.blogspot.com/2015/07/post-war-eastern-tbm-variants.html):

SW72130 Avenger AS.4

SW72131 TBM-3S2

SW72132 TBM-3R

The TBM-3R was the first real COD (Carrier Onboard Delivery) in the U.S. Navy. For more, see https://tailhooktopics.blogspot.com/2013/01/tbm-3r-cod.html

One of the significant differences among these versions is the various canopy iterations from the standard one with a prominent machine gun turret. As a result, the TBM-3R kit makes it easy to create a fourth and very colorful variant, the TBM-3U.


The U for Utility TBM was a modification of existing one involving the removal of all offensive and defensive equipment and addition of a target-tow capability. The canopy was basically identical to one of the TBM-3R variants.

This is a notional inboard profile:

Note that the tow reel might be mounted higher to fit within the width of the lower fuselage at that point. The circular structure on which the turret was mounted would probably still be present.

The tail hook might be internal or external depending on the TBM used for the conversion or removed entirely.

Internal

 

 External (note the cutback of the lower gun tunnel)

 This is probably a TBM-3J (note that it still has a rear turret) with the external tailhook removed:

The tow reel might look something like this, less the structure aft of the reel (this is the pod-mounted AD Skyraider tow mechanism):


Although later target-tow airplanes had engine gray fuselages, as of May 1946 they had gloss Sea Blue fuselages as well as an 18-inch wide walkway on the upper surface of the wings adjacent to the fuselage. The upper and lower surface of the wings and horizontal stabilizer were to be Orange Yellow as well as the vertical fin (the rudder was to be Insignia Red). A 36-inch wide Insignia Red band was also to be painted on the upper and lower surface of the wing about one third of the distance outboard from the fuselage to the wing tip.

Sunday, June 28, 2020

FJ-4 and FJ-4B Stores Pylons

Mads Bangsø asked for information on the FJ-4 and FJ-4B pylons. I knew the subject was complicated but had forgotten how complicated it was.

First, the FJ-4 was equipped with four external stores stations, outboard and mid-wing, and the FJ-4B attack derivative with six: outboard, mid-wing, and inboard.

FJ-4 pylons:
FJ-4B pylons:
 Unfortunately, I don't have any drawings or dimensions for any of the pylons.

Second, only the mid-wing stations on the FJ-4 were plumbed for external fuel tanks. On the FJ-4B, the outboard stations were also plumbed for external fuel tanks.

After that, it gets complicated. What I'll call "pylon adapters" could be mounted at the stores stations as on this FJ-4 target tug.
Note that when the mid-wing pylon was removed, the plumbing connections were covered by a small fairing. I'm pretty sure that one wasn't required on the FJ-4 outboard station.

Pylons suitable to the store to be carried were attached to the pylon adapter.

I don't know if the Sidewinder was carried on a bespoke pylon attached directly to the wing or it also utilized the adapter.

The pylons get really complicated on the FJ-4B:
All the stations could carry rocket pods or Bullpups (if armed with Bullpups, the right inboard station was used for a Bullpup-control pod.) The outboard stations were capable of carrying a 150-gallon Douglas fuel tank on a dedicated pylon and the mid-wing stations, the standard FJ 200-gallon tank, a Mk 7 nuclear weapon (left side only), or the North American inflight-refueling tanks. Note that the different stores required different pylons and some did not utilize the adapter but were attached directly to the wing.

Also, the inboard adapter was different:

Missing from the above display are the unique Bullpup pylons.

 However, the adapter on the right inboard station was utilized for a pylon to which was mounted the Bullpup control pod.

The refueling pods pylon (the right pod carried the hose and reel in addition to some fuel):
It appears to have been attached directly to the wing.

The Mk 7 pylon was also attached directly to the wing:
As was the outboard pylon for the 150-gallon tank (the tip of the outboard tank seems to be bulged but that is the nose of a tank mounted on the mid-wing station).
Whereas the 200-gallon tank on the mid-wing station utilized the adapter the same as the FJ-4:

The standard nuclear strike configuration was the Mk 7 and three external tanks:

Rocket pods were hung from pylons mounted on the adapters;

This FJ-4B has a pylon on the mid-wing station for bombs, no adapter (it appears to be identical to the pylon used for the inflight-refueling pods):

And lastly, when there were no adapters or bespoke pylons, a small fairing was substituted near the aft end of the station (the dark areas on the most outboard fairing are from the location of the national insignia), even for some reason, the inboard one, at least on the right side.

Wednesday, June 10, 2020

F8U-3 Monograph - Last Chance!

A big part of the McDonnell F4H-1 story is the fly off with Vought's F8U-3, the best airplane that the Navy didn't buy, according to George Spangenberg, the Director of BuAer's Evaluation Division at the time. Steve Ginter is down to his last box of my F8U-3 monograph that provides much more information and background on that program than I could include in my F4H-1 monograph. For the whole story, I recommend that you include both in your library.


If you do buy one or both, I suggest that you do so directly from Steve Ginter so he gets the full value of the sale:

For the F8U-3, see http://www.ginterbooks.com/NAVAL/NF87.htm

For the F4H-1, see http://www.ginterbooks.com/NAVAL/NF108.htm

Sunday, April 12, 2020

F4U-5 Redux

Why the chipmunk-like filled cheeks on the F4U-5? The reason was the addition of air ducts leading from the inlets on the cowl ring back alongside the engine to the -5's auxiliary stage superchargers aft of the engine.
For more, see https://tailspintopics.blogspot.com/2017/04/the-last-propeller-pulled-corsairs-f4u.html

Wednesday, April 1, 2020

Lockheed P2V-3 Neptune

Lockheed designed and built P2V patrol bombers with seven different dash numbers, all powered by the Wright R-3350 engines. The XP2V-1 first flew in May 1945 as the war in the Pacific neared its end. Three more dash numbers, generally associated with ever increasing takeoff horsepower, followed in fairly short order but none were built in large numbers due to the austere military budgets that followed World War II. The P2V-5, with yet another more powerful R-3350, first flew in December 1950, just in time to benefit from the resumption of military spending engendered by the Korean War. Almost 500 P2V-5s and MR.1s were built. It was followed by a relatively small quantity of P2V-6s, theoretically capable of fighting its way in and out of shipping lanes and harbors where it was to lay mines, and 287 of the final dash number, the -7, which was soon optimized for antisubmarine warfare.

 For a pretty good summary of the various Neptunes, click HERE

Since the Japan Maritime Self Defense Force utilized the P2V-7, it was appropriate for a Japanese plastic model-kit manufacturer to produce one in this configuration. It was first released in 1972 and has been frequently reissued with different decals. While some of configuration details, notably the canopy, are unique to the -7, "cottage-industry" conversion kit manufacturers have provided the details necessary to backdate the -7 to the -5. See http://tailspintopics.blogspot.com/2020/03/lockheed-p2v-5-vs-7-neptune.html

However, my main interest in the Neptune is that the Navy optimized a handful for a very specific mission after World War II, the delivery of a nuclear weapon from an aircraft carrier. This was the P2V-3C. While the conversion to a -3 is more extensive than creating a -5 from the -7, it is not a significantly higher degree of difficulty. For a detailed -3 conversion build-article by Edward Ellickson, aka TheRealMrEd, click HERE. It is profusely illustrated. Even though you may not be interested in a P2V-3 model, it is entertaining and informative, with lots of modeling tips and descriptions of a few problems necessitating creative solutions. Moreover, unlike some of us (me for one), Ed completes his challenging projects.
Edward Ellickson model and photo

While the P2V bomb bay wasn't big enough for the Mk 4 atomic bomb, it could accommodate the original Mk 1 and carry it a long way, particularly after fuel tanks were added to the nose and aft crew compartment. As a result, it was a quickly created placeholder until the North American AJ Savage, which was literally designed around the Mk 4, was ready to deploy. To reduce drag, the radar was moved to the nose and the upper turret was removed, along with the tail bumper and every other external excrescence.
The P2V-3C was to be deck launched from the big Midway-class carriers by utilizing JATO.

The initial plan was to recover it back aboard by the usual means, but after an evaluation of the degree of difficulty during field-landing trials at Patuxent River, the tailhooks were removed and the operational concept was to crane the P2V-3Cs aboard when required. This picture was taken during the tailhook proof-load testing at Lockheed.





More later...






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.