by Tommy H. Thomason

Tuesday, January 31, 2012

AD Skyraider Modeling Notes Redux

I've added some more information and illustrations on the nose flaps and the asymmetric fin to the AD Skyraider Modeling Notes here: http://tailspintopics.blogspot.com/2011/10/ad-skyraider-modeling-notes.html

Thursday, January 26, 2012

Nuclear Banshees Redux

Thanks to the Gerald Balzer collection as channeled by Mark Nankivil, I now have much better pictures of Mk 7 and Mk 8 nuclear weapons loaded on the F2H-3/4 Banshee. (Note that in the picture above, this -4 does not have the triangular fairing on the leading edge of the horizontal stabilizer that was added to cover an aft fuselage stiffening modification.) As a result, I've updated the Nuclear Banshee post here: http://tailspintopics.blogspot.com/2009/11/nuclear-banshees.html

F9F-3 Panther


The only notable differences that I know of between the Grumman F9F-2 and -3 is that 1) the -2 was powered by a P&W J42 engine and the -3, an Allison J33 and 2) the -3 with the J33 engine was never modified to carry bombs or rockets as the -2 was. The -3 was delivered first, to VF-51 to replace their FJ-1s. The picture above was taken during carrier qualifications aboard Boxer. Only 54 F9F-3s were produced; most had the J42s substituted for the lower-thrust J33s and were redesignated as -2s. According to Baugher (http://www.joebaugher.com/navy_fighters/f9_3.html), the changeover was accomplished in October 1949.

The earliest F9F-3s and -2s also appear to have a slightly different ejection seat headrest. See  http://tailspintopics.blogspot.com/2016/03/early-us-navy-ejection-seat.html

I'm therefore not sure whether VF-51 deployed with -3s per se. It and sister squadron VF-52 were aboard Valley Forge in the western pacific in mid-1950, just in time to be in on the start of the Korean War. LT(jg) Leonard H. Plog of VF-51, reportedly flying a -3 (BuNo 123071, modex 109S), made the first carrier-based jet kill, a North Korean Yak-9., in July 1950

A picture of VF-51 F9F-3s, according to the caption, deployed aboard Valley Forge is provided below. Note the lack of "Navy" and "VF-51" on the side of the aft fuselage, the unusually large number on the nose, and the large "104S" under the left wing. The later markings would be smaller and in addition to "Navy"and the squadron identification on the fuselage, there would be "Navy" on the underside of the left wing. The erosion-resistant leading edge treatment (see http://tailspintopics.blogspot.com/2012/01/corogard.html) on the leading edge of the wing, inlet, tip tank, and empennage is also clearly less wide on these F9F-3s:

Hobbyboss has  recently released a 1/72 kit of the F9F-3. I don't know if they have corrected the errors in their F9F-2 kit (see http://tailspintopics.blogspot.com/2011/05/172nd-f9f-2-panther.html).  Markings are provided for VF-51. However, VF-51 made a second Korean war deployment, only in -2s aboard Essex, and it appears that the markings in the kit are those of VF-51's F9F-2s, not its F9F-3s. In the photos I've seen so far like the ones above that are definitely VF-51 F9F-3s, neither "Navy" nor "VF-51" is marked on the aft fuselage. In a movie clip, I did note a red area at the top of the fin and on the nose, unlike the above. F9F-3 109S reportedly never got a kill marking, either, as shown in some illustrations.  (See www.history.navy.mil/nan/backissues/1990s/1997/mj97/plog.pdf)

In any event, the stores pylons should not be used; the J33-powered F9F-3 were never modified to carry rockets as shown on the box art like the -2s were.

Tuesday, January 24, 2012

F-111B Redux

Late last year, I found more F-111B photographs as well as bits and pieces of documentation in the files at the Grumman History Center. I've used them to update on the F-111B post (http://tailspintopics.blogspot.com/2009/10/grumman-f-111b.html) with better illustrations of the various tailhook installations, the short-nose forward fuselage shape, and the nose landing gear.


Tuesday, January 17, 2012

F-111B Inflight Refueling Probe

I'm now pretty sure what the F-111B inflight refueling probe installation looked like, both originally and as planned for the production aircraft.

Thanks to Ray Geminski, we now have a photo of the short-nose probe extended:
My guess is that this is #5, BuNo 151974. One of the test points for #4, BuNo 151973, the day in crashed at Grumman was an evaluation of inflight refueling so it also had a probe.

The probe for the original short-nose design was located just aft of the bulkhead that the radar was mounted on. It swung up from the left side of the fuselage.

And then swiveled forward into position like the A-6 Intruder's.

In this picture, you can see what look like two of the three doors associated with the probe. My guess is that the lower door was hinged on its forward edge. The middle door was attached to the probe (see the picture above). The upper door was hinged on its right side and covered the opening at the base of the probe.

Although the probe was not installed on the first two or three flight test aircraft, it was on the fourth for certain because an inflight refueling evaluation was planned on what would be its last flight. I believe the picture of the unpainted F-111B and the one with the probe extended are both #5.

The extension of the nose for production allowing a more straightforward installation. The probe was now stowed on top of the nose under two doors and rotated up into position without having to swivel.
However, it doesn't appear that either of the two flight-test aircraft with the production nose had this installation. This was probably because the contour of the upper nose was different between the radome and the escape capsule on these airplanes. They were fitted with the original escape capsule whereas the production airplanes were to have a lower interface between the windscreen and the upper nose for better over-the-nose visibility. (See http://thanlont.blogspot.com/2009/03/f-111b-carrier-trials.html) In any event, the airplane had more than enough internal fuel for the typical flight-test mission so inflight refueling was not required.

Saturday, January 7, 2012

Corogard

Corogard*—also spelled Corrogard, Coroguard, Coro-gard, etc—was required by the Navy on the forward facing edges of inlets, wings, and empennages of some airplanes beginning in the mid 1950s. It was a clear epoxy paint that provided an additional degree of erosion and corrosion protection to those surfaces. The Navy specified that it be "aluminized" by the addition of aluminum power.

It's not clear when this requirement was first implemented. Don Fogal found a reference to the requirement in Squadron/Signal, Navy Air Colors, Vol. 2, 1945-1985, which cited specification MIL-C-18263(Aer) dated 23 February 1955 that revised paint and markings, including the introduction of the new gray/white paint scheme.

"The leading edges of airfoils and frontal surfaces were to be painted in an approved rain-erosion resistant finish. At this time the approved finishes for metal surfaces were an aluminized color and those approved for glass fiber reinforced plastic assemblies varied from Natural Tan to Black. The erosion-resistant finish was to be applied in such a manner that it would extend from the first row of rivets or fasteners on the upper surface to the first row of rivets or fasteners on the lower surface."

The use of Corogard or a clear erosion-resistant coating on the leading edge of the wings and empennage of jets predates this document and was not necessarily limited to the first row of rivets. However, the width of the erosion-resistant application was almost certainly controlled by a paint and marking for each airplane type and therefore always the same. For example, this is the Vought drawing that defines it for the F8U wing.
Note that the Navy repair and overhaul might differ.

The leading edges of Navy jets were originally painted with the overall color.

However, high speed flight tended to remove the paint from the leading edges of the wings and empennage. The original fix appears to have been to leave these surfaces unpainted as on this early F9F Panther.


 Also see http://tailspintopics.blogspot.com/2012/01/f9f-3-panther.html

Note that the amount unpainted surface on the Panther was subsequently increased.

There was likely some sort of corrosion protection provided on the leading edges, possibly a clear coat or post flight oiling. In any event, the use of the Corogard to protect the leading edges soon became standard. The practice was reportedly initiated at Grumman although I haven't been able to confirm that.




This is an example of the requirement for leading edge protection on the McDonnell F-4 (F4H) at a Navy Repair and Overhaul Facility:

This is a picture of the Sageburner F4H at the Smithsonian's Silver Hill storage facility. I'm not sure how soon the inlet was covered after the airplane was placed in storage by the Navy.

Since it was a relatively thick coat of clear epoxy mixed with aluminum powder, the perceived color and shininess varied with lighting and length of time since it had been applied. Some knowledgeable observers report it as being close to silver when new but that it weathered to a light gray. Another reported shade is close to aluminum lacquer paint. Another description is “semi-gloss medium metallic gray.”

Note the difference in the following two pictures between the leading edges of the wings and vertical fins.

It gets even more difficult to see in gray-scale pictures:

Unless the application is fresh and the lighting is right:

There are very complicated ways to replicate it, but I tend toward just spraying on matte silver.

It appears that at some point the Navy stopped using Corogard and left the leading edges natural metal, for example on the F-14. A subsequent innovation was to use a yellowish tape on the leading edge, possibly only subsonic jets. The lack of paint on the leading edges of F-14s is described here but the link has become broken.

*3M filed for the wordmark "Corogard" in October 1951 and it was registered a year later. It is described as a "transparent protective coating material applied in liquid form ... said protective coating material drying after application to form a hard, tough transparent film." 3M allowed the trademark to expire in 1993.

Tuesday, January 3, 2012

Not a Jeep

David Collier provided me with a correction to a caption in Air Superiority. On page 49, there was a picture of an early F6U with an NC-1. I had written "The yellow low-slung jeep-like cart carries the array of batteries need to start these early jets." It turns out that this was the replacement for the jeep that lugged eight batteries around the deck and it didn't provide electrical power from batteries.

The new three-wheel NC-1 was equipped with a gasoline-powered generator to provide 24-volt current and also alternating current. It supplemented the fixed power stations at the catapults so the jets could be started elsewhere. The new starter jeep was modified from a standard jeep by O.E. Szekely & Associates of Philadelphia. The two wheels in the front were turned by the engine (i.e. front wheel drive) and did not turn for steering. The steering wheel (now mounted straight up and down) was connected to a third wheel under the back of the cart, allowing it to be turned in its own length. Deliveries began in late 1949 or early 1950.
The configuration changed over time. The one above may be an NC-1A, the suffix possibly added with the wedge in the hood covering an engine modification. The one wheel in back was apparently replaced by two and "training wheels" or "roll bars" were added at the rear corners to eliminate tip-over incidents. David provided the picture above as well as the following to illustrate the different configurations.

No anti-tip provisions, no wedge on the hood.

Wedge on the hood, training wheels:
 
No wedge on the hood, skids on the rear corners:

The NC-1/1A can be created from a jeep kit with some work. Alexsandr Survorov aka Phantom wrote about it here: http://www.dishmodels.ru/gshow.htm?p=5835&lng=E

This is a picture from that article of his conversion of an 1/72nd scale Hasegawa kit:
The NC-1A was replaced in the 1960s by larger, low-slung vehicles with turboshaft jet engines turning the generators. They could also be employed to tow aircraft. For more on flight deck tractors and start carts over the years, see http://www.carrierbuilders.net/forum/index.php?showtopic=1176

For more on the later tow tractors and power supply vehicles, see http://robdebie.home.xs4all.nl/models/mule.htm