by Tommy H. Thomason

Sunday, March 6, 2011

Recent Topic Updates

Added a couple of pictures and made wording changes to the Trader/Tracer entry HERE.

The S2F Stoof entry HERE was expanded yet again today with cockpit information and a link to the Belcher Bits blog showing a problem in length with the aft fuselage for the S-2E/G and the changes required to shorten the forward fuselage for the S2F-1/2. You might also want to look at the comments for Kinetic kit information.

The F8U Crusader entry HERE has been updated with comments and corrections provided by Tom Weinel.

If you have a specific request rather than a compliment, correction, or addition pertinent to the topic, it's best that you send me an email rather than submit it as a comment. My email address is tommythomason@sbcglobal.net.

Friday, February 11, 2011

Super Fox

The A-4F was originally powered by the Pratt&Whitney J52-P-8B engine rated at 9,300-lbs thrust. Many, reportedly 100 of the 147 built, were modified for the P-408 engine, with 11,200 lbs of thrust. For some reason the Navy didn't bother redesignating them as they usually did for a change of this type and magnitude. Informally, they were known as Super Foxes. The only external indication of the more powerful engine is the bigger inlet required for maximum low-speed thrust. When stripped of unnecessary weight and drag for use as a MiG surrogate in dissimilar air-to-air combat training, it was a formidable foe with its relatively high thrust-to-weight ratio, very high roll rate, and a small visual signature.

I had heard about the increase in the inlet size on the Super Fox, but for a long time assumed that it was an interior change because it is so subtle. From the side, it is very difficult to discern the exterior bulge because the depth of the inlet did not change, at least not on the outside. The Blue Angels' A-4s were Super Foxes, but I defy you to see the bigger inlet in this picture of No. 5 beginning the dirty roll to the left on takeoff:

The A-4Ms were also powered by the P-408 engine and had the bigger inlets but again, from the side, it's almost impossible to tell. (If you read on and then come back to this picture, you may be able to see a hint of it.)

However, when viewed from below or directly above, the outward bulge in the first three feet or so of the exterior is very apparent.


Compare the exterior of the inlet in the picture above to this top view drawing of the stock A-4F:


From the side, the bulge can also be seen in certain lighting.
In this case, you can see the crease of the start of the bulge. Its begins at the panel line that cuts through the aft end of the inlet warning triangle. The change in contour, which is normally very hard to discern, then angles up and forward on the inlet so that there is no bulge at the top. A similar crease is probably present on the lower half of exterior of the inlet but isn't evident here.

Thursday, February 10, 2011

The F8F-8T Cougar

I've noted a couple of inqueries on modeling websites about the alternatives for creating an F9F-8T (TF-9J) from a single-seat F9F-8. This isn't as easy as it looks at first glance. The two-seat Cougar trainer had a new forward fuselage beginning at fuselage station 172 (pretty close to the aft end of the speed brake well) as well as a new canopy and a fairing aft of the canopy. However, neither the speed brakes nor the nose gear well was moved forward relative to the mid-fuselage so the wheel base remained the same. The trainer retained two of the four cannons. (For more see http://www.ginterbooks.com/NAVAL/NF68.htm)


The overall length increase (not counting the barrier deflector on the F9F-8 or the refueling probe on either the -8 or the -8T) was about 34 inches.

This provides a rough idea of the changes and what would be required if a conversion was attempted using a single F9F-8 fuselage:

Fortunately, there are alternatives in each of the major scales:

The Miniwing kit is 1/144th scale. It is reviewed Here

Until early 2016, there was no 1/72nd scale F9F-8T kit per se. There were at least four different conversions that been issued that can could be used with the Hasegawa Cougar: Airmodel AM-049 (vacuform fuselage and canopy), Esoteric/Body Job BJ-4 (resin fuselage, vacuform canopy, and decals), RVHP 7239 (resin and ?), and Falcon Triple Conversion III (vacuform fuselage and canopy) that also provides conversions for the F-106B and the Mirage IIID. The Airmodel conversion is pretty crude and probably a last resort. The Esoteric one is long out of production. The RVHP conversion is still available but might be hard to find. The Falcon conversion is still available from their retailer in New Zealand and from Hannants.

Paul Boyer converted a Hasegawa F9F-8 with the forward two thirds of the Esoteric fuselage. The Hasegawa parts are white and the Esoteric fuselage, resin colored.
Paul:  "(Esoteric) clearly used the Hase kit as the basis, but the tailpipe and hook area was solid and the bottom had a lot of bumps and bubbles. I chose to pitch it and cut it away and use the Hasegawa tail. Other problems encountered: The cockpit has vertical sidewalls that are even with the canopy opening, so there are no consoles. The white-metal seats sit too low, and the canopy is too bulbous in retrospect. Since the framing was indistinct, I may not have carved enough off the bottom. The nose-gear well is awful -- don't look in there."

"The conversion kit decals were nearly worthless -- no stenciling and only basic markings for a trainer and a Blue Angel bird. I found this one in the Ginter book on the F9F-8T/TF-9J. The blue sash on the nose is paint and it matches the blue stripe decals cut from solid color sheet for the tail. Note the blue stripes leave a white outline on the "NAVY" on the rear fuselage. No way I was going to cut that pattern into the decal stripes, so I applied each letter of "NAVY" onto white solid-color decal, let them dry, then carefully carved the letters out of the white sheet with white outlines. The rest of the letters and numbers came from various lettering sheets by Microscale and Scale-Master. The intake warning chevrons came from a Microscale Panther sheet provided by member John Huggins. Thanks, John!"


Will Alcott used the Falcon conversion to create a USMC Fast FAC. In this case, the Hasegawa kit is blue plastic, the Falcon vacuform is white, and the primer is gray:
The result is quite striking; yours may vary, particularly since the Falcon conversion doesn't come with decals: for example, the shark mouth is Will's combination of masked off black paint and red permanent marker:

Fortunately, Sword has now issued a 1/72 scale injection molded kit, SW 72093.
 It is based on the Hasegawa F9F-8 but was completely retooled and therefore different in detail, sprue configuration, etc. Only Martin Baker seats are provided but that is acceptable because the Grumman seats were soon replaced. This particular kit only provides decals for three different trainers:
However, it seems likely based on past experience that Sword will reissue the kit with USMC Fast Fac markings from the Vietnam War and also Blue Angels markings.

Collect Aire produced a 1/48th kit in resin which is reviewed Here
(It is out of production but might be found on eBay from time to time)

In mid 2014, Kitty Hawk released a 1/48th injection molded kit of the F9F-8T/TF-9J. See here for more details: http://tailspintopics.blogspot.com/2014/06/grumman-f9f-8ttf-9j.html

Fisher Models sells a 1/32 F9F-8T kit: See it Here on page 2.

The F9F-8T was originally delivered with Grumman-furnished ejection seats. However, in 1956 BuAer contracted with Grumman to install the new Mk 4 M-B seat in an F9F-8T for a demonstration. Flying Officer Sidney Hughes, RAF, successfully ejected from it at Patuxent River in August 1957 while on the runway at 120 kts.
The demonstration resulted in an order for Mk 5 ejection seats (the major difference was higher crashworthiness) for all the Navy fighters and the F9F-8T to replace the existing contractor-furnished seats.

The original Grumman seat is on the right and the Martin Baker seat used for the test is on the left (some of the details changed over time like the harness; the original RAF harness is shown).


Grumman seat installed
Martin Baker seat installed

Saturday, January 29, 2011

A4D-1 Vortex Generators

Vortex generators are small tabs mounted at an angle on the surface of the airplane skin. Their purpose is to introduce energy into the boundary layer, the slow-moving air immediately adjacent to an airplane wing or fuselage. They are added when required to solve problems found in flight test like buffet, wing drop, aileron effectiveness, etc. Their use is undesirable because they have to be mounted at an angle to the free-stream air, which adds drag. However, sometimes there is no other way to solve the problem.

The A4D is an example of their use to solve aerodynamic problems. An extensive trial and error program resulted in an interim pattern of vortex generators used on the A4D-1 and a different one on the A4D-2 and subsequent Skyhawks. Here is an example of a pattern that was evaluated and not adopted:
Note that there are vortex generators on the fuselage and upper surface of the wing adjacent to the fuselage as well as on the wing just aft of the leading edge slat.

The actual pattern used on production A4D-1s were on the leading edge slat itself along with six on the fuselage, in this case ahead of the mid-fuselage break. (There are also two on the wingtip itself.)
The ones on the slats were an alternating pattern of long and short and angled left and right.


Note that the barricade engagement fences have not yet been added to the slat as they would be on production A4D-1s.

The vortex generators on the fuselage were not always in a line vertically.
Sometimes the lower two were missing.

During production of the A4D-1, a different arrangement of vortex generators was developed for all subsequent Skyhawks. The ones on the fuselage were deleted, a different pattern (same number) was used on the leading edge slats and the wingtip, and a second row was added on the wing ahead of the ailerons. (Note the fences for barricade engagement on the leading edge slat.)



There are no kits of the A4D-1 as good as those of the A4D-2 (A-4B). However, the vortex generators are not the only difference between the -1 and A4D-2 (A-4B). A conversion from an A-4B also requires the removal of the inflight refueling probe and a "solid", i.e. non-ribbed rudder. The A4D-1 carried 150-gallon tanks early on as shown in the following picture. Note that every other vortex generator on the slat (which has been locked up) is edge-on to the camera, making them appear to be missing...


For completeness, here is an early A4D-1 cockpit:

And an early A4D-1 ejection seat:

Note that at least one A-4A was subsequently modified to have the additional row of vortex generators on the wing, while retaining the ones on the fuselage. Other A4D-1s are likely to have been modified to this configuration during Navy overhauls, as well as having the vortex generators on the fuselage deleted.
(The trough under the tailpipe is an experimental modification for IR suppression.)

Thursday, December 30, 2010

F8F Bearcat: -1 vs -2


The most obvious external differences between the Grumman F8F -2 Bearcat in the lead picture above and the F8F-1 were the 12" taller vertical fin and rudder and the 20mm cannon armament (the latter was also a feature of the F8F-1B, the B suffix indicating a change in armament) indicated by the longer barrels and the bumps on the upper surface of the wing.
The drawing above turns out to be incorrect. See http://tailspintopics.blogspot.com/2016/07/grumman-f8f-bearcat-vertical-tail.html

A not so obvious difference was the windscreen. See  http://tailspintopics.blogspot.com/2016/07/grumman-f8f-bearcat-windscreen.html

There was also a difference in the engine installation. Reportedly (see Davis Gandees comment below and HERE:) only the first 23 "pre-production" F8F-1s had 5 exhaust stacks.

According to Gandees (and a subsequent comment by anonymous), the remaining F8F-1s had three exhaust stacks. The following sketch showing a fairing added to the trough to cover two lower stacks is is therefore incorrect.


The -1 shown here has the production exhaust trough with the lower side raised above the wing to smooth the flow over the wing and horizontal stabilizer.

 This is the -2 trough with three exhaust pipes.

Air that had passed through the oil coolers was dumped through two "shutter" controlled doors between the inner main landing gear doors. These are the doors on the F8F-1:
Picture by Craig/J361 on Hyperscale

These doors were a slightly different configuration on the F8F-2. They were longer, extending farther forward, and had a scalloped cutout on the inboard side. Note that the F8F in the following picture is a warbird so the interior color of the landing gear doors and the wheel well shouldn't be relied on.
Picture by Ron Cline

A fixed oil cooler vent was also added across the bottom of the aft end of the -2 cowl (Mark Hayward picture of a warbird from the Prime Portal F8F Walkaround so again, the wheel well color shouldn't be relied on):


Mike West of Lone Star Models sells resin 1/48 F8F-1 and -2 cowls as well as other F8F improvements. Chris Bucholtz of Obscurco also offers a replacement F8F-2 cowl for the 1/48 Hobbycraft kit.

Some notes on the main landing gear wheel well: https://tailspintopics.blogspot.com/2014/07/f8f-bearcat-wheels-and-wheel-wells.html

With respect to the breakaway wing tips: https://thanlont.blogspot.com/2012/10/f8f-safety-tipsit-seemed-like-good-idea.html

For much more detail on the F8F Bearcat and operational usage, see Steve Ginter's excellent monograph written with Grumman's Corky Meyer. It's also available from Sprue Brothers.

Friday, December 10, 2010

Blog Entry Changes

28 December 2010: Minor additions and corrections on the FJ-3 and FJ-4 Fury (October 2009)

13 December 2010: Minor corrections for the AD-5W seating in the Wide Body Skyraider (December 2009)

10 December 2010: Added matrix of configuration differences by BuNo and production Air Force F-111s to the F-111B entry (October 09)

23 November 2010: Added information, including additional cockpit illustrations, to early Phantom IIs (November 09)

1 October 2010: Modified the F-111B entry to provide more comments on the Revell kit and a picture of the ejection seat canopy modification (October 09)

20 September 2010: Added comparison of F-86 and XFJ-2 windscreen (October 09)

Sunday, December 5, 2010

Vigilante!

19 November 2021 Update on bombing accuracy

This is once again a work in progress, last updated on 6 December in the AM. I'm on the road so I don't have access to all my files. There may therefore be more errors and misstatements in the following than usual. Even then, it will pale beside the information available at Bob Jellison's website.

When the first pictures of the A3J-1 were published in Aviation Week, I thought it was the most beautiful airplane that I had ever seen.  It was intended to replace the carrier-based, long-range atomic bomb delivery capability then provided by the Douglas A3D Skywarrior, except it was supersonic with a unique weapon delivery system. As it happened, only 59 were built, including the two prototypes, since it was the victim of a budget battle won by the proponents of the submarine-launched Polaris missile.

The nuclear bomb was carried internally but not dropped. Instead it was propelled rearward, attached to empty fuel tanks, out the back of the airplane at about 30 knots, not at the same speed as the aircraft as is sometimes stated and the store also did not get sucked along, affecting bombing accuracy as is frequently reported; it worked as advertised. However development of satisfactory accuracy and reliability of the bombing system was not achieved by the time it was apparent that Polaris was the better alternative for the requirement.
Before the bomber version was cancelled, however, the range of the Vigilante was to be improved with the A3J-2. Additional fuel was added by increasing the height of the fuselage over the wing and adding two additional external stores pylons. The extra weight was accommodated with a bigger wing and flaps and the addition of boundary layer control to the leading edge flaps. The engine inlet was also modified. Note that in the -2 prototype, the bleed air piping for the leading edge slats ran forward in the armpit of the wing.
The Navy ordered 18 -2s but only two were completed as such. The next four were built to aerodynamically represent a reconnaissance version, the A3J-3P, and used for transition training in the replacement air group squadron. (The leading edge BLC piping was relocated to above the wing and integrated with the overwing fairing.) The last 12 became the first RA-5Cs, the redesignation of the A3J-3P in November 1962.

These two pictures illustrate the difference in wing planform between the A3J-1 and the RA-5C.
If you look closely at the pictures (click on them first) you'll see two different positions of the unusual A3J/RA-5 lateral control system, one to roll left and the other to roll right. There were two sets of spoiler/slot/deflector controls on each wing, one to raise it and the other to lower it. The spoilers were hinged at the leading edge and the deflectors at the trailing edge to direct air flow through the slot.
All four sets were opened simultaneously to function as a speed brake.

The RA-5C was probably the best, certainly the most capable, reconnaissance airplane the Navy ever operated from carriers. It has never been replaced with anything comparable. It was fast, with good range/endurance, and big enough to carry an internal equipment pallet and a belly pod that could be fitted with cameras, side-looking radar, and electronic signal detectors. It retained the weapon delivery capability using the stores pylons but it is unlikely that it was ever used as an attack airplane, considering the RA-5C's value as a reconnaissance platform and that relatively few were assigned to each carrier air wing.

Counting the 12 A3J-2s that were completed as RA-5Cs, 91 RA-5Cs were built for a total of 156 aircraft:
2   XA3J-1s                     BuNos 145157/8
57 A3J-1s (A-5As)          BuNos 146694/708, 147850/863, 148924/933, 149276/299
2   A3J-2 prototypes        BuNos 149300/1
4   YRA-5C (YA3J-3P)  BuNos 149302/5
12 RA-5C (A3J-3P)        BuNos 149306/17
43 RA-5C (J79-GE-8)     BuNos 150823/842, 151615/634, 151726/151728
36 RA-5C (J79-GE-10)   BuNos 156608/653

The nomenclature above is not precise in all cases since it is intended to differentiate between the various contracts, initial intentions, etc. Note that -3 is not a typo.

The 91 RA-5Cs built were augmented by conversions of earlier production. Not all sources agree, but Joe Baugher's website provides a list of conversions by BuNo. According to his tally, there were 43 A-5As converted including one of the A3J-1 prototypes. In addition, the first six of the original order of 18 A3J-2s were rebuilt to the RA-5C configuration, for a total fleet of 140. Some sources state 134, with the difference likely being the omission of the two A3J-2 prototypes and the four YA3J-3Ps. Of course, due to attrition (almost half of the A-5s built were destroyed in accidents and combat), the fleet never totaled 140 aircraft at any time. In fact, the production line was restarted, a very rare event, to build the last block of aircraft in order to bring the numbers back up to a satisfactory level.

The last new-build RA-5Cs were slightly different in addition to being powered by the J79-GE-10, which had a notably different afterburner nozzle.

Also see http://tailspintopics.blogspot.com/2012/12/j79-exhaust-nozzles.html

The engine inlet of the last new-build aircraft had a different outboard shape, being straight instead of curved, and a small leading-edge extension was added along the side of the nacelle.

Early RA-5C inlet:

Late RA-5C inlet and leading edge extension:

There were, of course, detail changes over time to the ECM antennas, tail cone, etc. It also appears that some of the conversions from A-5As (and a couple of early build RA-5Cs) were to the later build inlet configuration with the leading-edge extension like BuNo 146702 shown here. Note that the RA-5C vertical fin tip slopes downward from front to back due to the addition of an IFF antenna.
From photographs, Craig Kaston has identified the following BuNos as receiving the late-build configuration: 146702, 149276, 149287, 149299, 149301, 150831, and 151630. Note that the last two were originally delivered as RA-5Cs in the early configuration.

Trumpeter has produced both 1/72nd and 1/48th kits of the RA-5C. It is reportedly a mix of features of the early and late configurations, but the major knock on the kit is the shape of the forward fuselage and vertical fin. For comparison, here are Rockwell drawings. (The first one shows the tip of the vertical fin as being roughly straight across, which is incorrect for almost all, if not all, of the RA-5Cs.)


As usual, Steve Ginter offers one of the best monographs on the subject, North American A-5A/RA-5C Vigilante Naval Fighters Number 64. It is also generally available from Sprue Brothers, along with lots of other Vigilante kits and stuff.

   To be continued...