Grumman A-6 Intruder History

The best history ever written on the A-6 Intruder is by Mark and Rick Morgan:

I'm going to go out on a limb here, since I haven't seen it yet, and say that the second-best book on the A-6 Intruder has just been released:

Note that it's by Rick Morgan who I rely on as a subject matter expert. It's available on Amazon and at a substantial discount.

Plus if you buy this book, you'll help convince a publisher to contract with Rick to do a similar work on the A-3 Skywarrior, which I for one would welcome, and a follow-on that covers the A-6s post-Vietnam.

Fitting In IV

The maximum folded span on a U.S. Navy carrier-based airplane and how it changed over time is obviously a subject of interest to me. See:
http://thanlont.blogspot.com/2009/07/fitting-in.html,
http://thanlont.blogspot.com/2010/07/fitting-in-ii.html,
and http://thanlont.blogspot.com/2010/07/fitting-in-iii.html.

To recap briefly, the 1949 XF3H mockup review report mentions a limit of 25' 4" due to the requirement for two airplanes to pass in the hanger. The span of what was to become the A4D was 25' when it was first laid out by R.G Smith. Based on the actual or proposed spans of some early 1950s single-seat jets, the limit was subsequently increased to about 27' 6".

One answer based on this 1948 Douglas proposal illustration is that it depends. Princeton was an early Essex-class carrier. The aircraft shown, an XF4D proposal, has a computed span when folded of 25' 9.5" based on the diagram (it was actually 25' 6"):

 Note that the clearance on the left side is only 18," whereas the other two clearance points are two feet apart, and that the clearance on the right is dependent on the height of the wing and then perhaps on the wheel base of the main landing gear. In other words, the limit for the folded span could vary somewhat based on the specific configuration of the airplane. Also, a subsequent ship alteration may have increased the width of this pinch point or resulted in the narrowest passage being someplace else on the hangar deck (fire-door openings didn't count). Another constraint as previously mentioned was the width of the elevator and the desire to move two aircraft up to the flight deck or down to the hangar deck at the same time.

Making It Harder Than Necessary?

Designing a carrier-based aircraft means dealing with several constraints that don't have to be addressed by designers of land-based ones. These affected folded size, weight, strength, takeoff and landing performance, etc. and varied by carrier class. However, in general, the designer was required to accommodate the most onerous. One across-the-board standard was the number that could be parted in the first 200 feet of an Essex-class carrier deck.

In the years following World War II, there were four basic U.S. aircraft carrier types:

Note that the elevators, deck width, and landing areas were roughly the same size. The major difference in size was total deck area with the escort carriers, CVEs, having the least. They were also much slower than the others, having a top speed of a bit less than 20 knots versus more than 30 for the bigger carriers including the CVLs.

The speed difference had a major impact on landing and takeoff performance requirements, since wind-over-deck was critical and the most that a CVE could generate in no-wind conditions was its own top speed. Because lift varies as the square of speed, that meant that the benefit of wind-over-deck in no-wind conditions was not about 30% less but more than 50% less.

In the early 1950s, due to budget and other considerations, only a few CVEs were deployable. However, many more were mothballed and available for recall if necessary. As a result, design requirements for new programs like the S2F and even the A4D jet attack airplane required operation from CVEs. Northrop proposed an early version of a lightweight fighter to the Navy in the early 1950s, without success, that was specifically focused on operation from CVEs.

Block Island was among the last of the escort carriers to deploy as such (some went to sea later as aircraft transports or communication relay platforms). Here CVE-106 is operating AF Guardians in the early 1950s as an ASW carrier.

It was put into reserve on 15 January 1954.

Having to deal with the lower wind-over-deck capability of the CVEs did provide naval aviators with extra margin when operating from the faster carrier classes. It also meant that the A4D Skyhawk could be successfully qualified to operate from former Royal Navy Colossus/Majestic-class aircraft carriers that had been modified with an angled deck, more powerful catapults, and stronger arresting gear like Melbourne, shown here alongside Kitty Hawk.

Having a Problem?

Somehow a string of what amounts to gibberish (to me, anyway) got inserted into the beginning of the text of "And Now for Something Completely Different". The only browser that couldn't seem to cope with it was Internet Explorer. I fixed it both here and on the most recent post in Tailhook Topics (http://tailspintopics.blogspot.com/2012/12/f-4s-wing.html). Since I don't have Explorer, if those of you who do and have a hang, please let me know with a comment on http://ththomepage.blogspot.com/.

Approach Lights Redux

It's surprising how often something new shows up for something old. I wrote about approach lights here: http://thanlont.blogspot.com/2012/04/night-carrier-landings-in-beginning.html

It was just brought to my attention that the F-4 had a green light on the left side of the fuselage that the LSO could use at night to determine roll attitude when he could not see the position light on the right wingtip, e.g. if the Phantom was turning left for lineup. It can be seen in this picture just below the crossbar in the A in NAVY. It looks like it is at the same waterline as the left-wingtip position light. I'm surprised that it is flush rather than protruding like a similar one is on the E-2.

The picture is cropped from a walkaround by Howard Mason of an F-4J on the Prime Portal website here: http://www.primeportal.net/hangar/howard_mason/f-4j_155563/

And Now for Something Completely Different

While doing research for my book on the development of U.S. Navy carrier-based jet fighters, I came across a cryptic reference to a proposed rocket-propelled interceptor.

I dismissed it out of hand although the Germans had not. In World War II, they developed the cannon-armed Me 163 interceptor that was rocket powered and had very high performance. One of the first aviation books that I remember reading as a preteen was Rocket Fighter by Mano Ziegler, a WW II Luftwaffe pilot who flew it.  Although legend has it that the Komet was more dangerous for its pilot than the B-17 crews that he was attacking, it was reportedly easy to fly and phenomenally fast for the time. The main problem was its fuel, C-Stoff (57% methanol/ 30% hydrazine/ 13% water), and oxidizer, T-Stoff (80% concentrated hydrogen peroxide / 20% oxoyquinoline. The combination was hypergolic, meaning it ignited just from being mixed, without the need for an ignition source. The Germans developed a process for safely fueling the Komet but a crash on takeoff or landing (particularly from the rough-and-ready fields available) was likely to result in an explosion or fire.

It turns out that the rocket-propelled interceptor proposal was a paper dated 8 June 1950 that was written by a U.S Navy officer, Commander Robert C. Truax, who was also literally a rocket scientist. It was a summary description and analysis promoting the development of a destroyer-based, rocket-powered interceptor.  In this case, furfuryl alcohol was the fuel and  nitric acid was the oxidizer. A small engine was provided for services and cruise;  a much larger one provided the thrust and control for vertical takeoff and acceleration.

In Truax's mission scenario, the interceptor would be launched vertically from the fantail of a picket ship, in this case a Gearing-class destroyer that would carry five of the aircraft.

After a flight profile measured in minutes, it would descend by parachute to the sea, from which it would be recovered to be prepared for its next mission.

 The range depended on the profile flown, ranging from zero ballistic (70 nm) to full ballistic (150 nm). Top speed was about Mach 4.

(Note that the full ballistic profile meant a recovery about 80 nautical miles from the launch point for a straight-out mission.)

An AN/APS-25 radar was to be used to locate and navigate toward the incoming bombers. 1,500 lbs of the 13,000 lbs gross weight was allocated to the weapons, which were yet to be defined. Aerial mines detonated by proximity fuses were one possibility.

In his paper, Truax noted that significant experience had been gained since the war with liquid-fuel rockets, including over 200 flights of the Bell X-1 with a rocket as its sole power plant. The Douglas D-558-2 was about to fly with a rocket engine. The smaller rocket engine in his design was one in development under contract to the Navy.

Although far-fetched, Truax's proposition received formal consideration at the Navy’s Bureau of Aeronautics and garnered at least one letter of support. However, even if the Korean War hadn’t become a distraction shortly thereafter, it seems very unlikely that the Navy would have taken any action on his rocket-powered interceptor after BuAer's review.

Truax retired from the Navy in 1959 as a Captain and went on to a career at Aerojet, after which he founded his own company, Truax Engineering. Among other things, he designed the Skycycle X-2 for Evel Knievel’s Grand Canyon jump. For more on Truax, see http://en.wikipedia.org/wiki/Robert_Truax .

F7U-1 Cutlass

My long overdue monograph on the F7U-1 Cutlass for Steve Ginter's Naval Fighters series is finally done and at the printer.

It is available from Amazon: http://www.amazon.com/dp/0984611479 , Sprue Brothers, Specialty Press, and Steve Ginter himself (http://www.ginterbooks.com/NAVAL/NAVAL.htm).

I guarantee that it has pictures and illustrations that you haven't seen before.

The F7U-1 was ahead of its time in many ways.

(Swept national insignia wasn't authorized until March 1955.)

Rogue markings were indicative of much more audacious decisions that resulted in F7U-1 development falling well behind schedule and the production program being terminated. I hope you agree that I've done its story justice.