The Japanese Spruce Goose: The Kawanishi H11K Soku

Profile of the H11K from the Anigrand 1/144 scale kit
(Anigrand Craftswork)

By 1944, the US Navy's unrestricted submarine warfare against Japanese shipping had reached its highest totals in terms of shipping sunk and it was taking its toll on Japanese industry. As an island nation with few natural resources, Japan was dependent upon shipping for the importation of raw materials and oil for not just its industry but also for it military forces. The Imperial Japanese Army Air Force looked at using transport gliders to bring oil from Sumatra to Japan, but the fuel costs to do so outweighed the volume of oil brought in. The Imperial Japanese Navy, however, with its experience in operating large seaplanes, asked Kawanishi to develop a large transport seaplane to make up for the shipping losses. Kawanishi had already designed and put into production two large flying boats, the H6K (Allied code named "Mavis") and the H8K (Allied code named "Emily"). The H8K in particular was avery well-regarded flying boat design, even by the Allies. Kawanishi had also modified its production flying boats for the transport role as well. The transport version of the H8K was designated H8K-2L Seiku ("Calm Sky") and the company had built 36 for the IJN for transport duties aside from the prototype which was converted from a front line H8K. Most of the defensive positions were deleted to save weight save a 13mm machine gun position in the nose and a 20mm cannon in the tail position. The fuselage fuel tanks were reduced in size to allow for more cargo volume. An H8K-2L could carry up to 62 fully-equipped troops.

Overall configuration of the H11K Soku
(Airwar.ru)

The earlier H6K also had a transport version. It didn't have the space or load carrying capability of the larger and later H8K, but 20 aircraft designated H6K4-L were built and another two were converted from former front line H6K4 flying boats. And earlier production run of 18 aircraft designated H6K2-L were primarily passenger aircraft used by Japan's wartime airline, Dai Nippon Kokku. As passenger transports, they could accommodate 18 passengers and had sleeper berths.

Kawanishi's design for a large purpose-designed transport flying boat was designated H11K Soku ("Blue Sky"). Since metal alloys were desperately needed in the production of fighters for homeland defense, Kawanishi's H11K would have been made of wood wherever possible- making it in a sense a Japanese counterpart to the Hughes HK-1 "Spruce Goose". Starting out by scaling up the H8K but having a nearly identical fuselage keel, the H11K was powered by the same four Mitsubishi MK4Q Kasei 22 1,850-hp radial engines, each engine driving a large four-bladed propeller 14 feet in diameter. By comparison, the large Martin JRM Mars had 16 foot, 8 inch four bladed propellers. Most of the wings and fuselage made of wood. Under each wing was a fixed float for water stabilization. The fuselage had two decks- the upper deck had not just the flight deck but also quarters for the crew of five. The lower main deck could accommodate over 80 fully equipped troops, vehicles or an equivalent volume of cargo. To speed loading and unloading operations, the nose had split clamshell doors. Three machine gun positions were located in the fuselage for self-defense. 

The H11K mockup with its nose clamshell doors
(RC Groups Forum)

After presentation of the H11K proposal to the Imperial Japanese Navy, full design work began in 1944 with Kawanishi building a full-scale mockup of the H11K for inspection and review by the IJN at one of its facilities on the west coast of Japan. However, the deteriorating war situation meant that  the full-scale mockup which was nearly completed on was destroyed along with most of the Kawanishi facilities in a bombing attack on 1 April 1945. No further work was attempted on the H11K Soku after the attack.

Some comparisons with other large Second World War-era flying boats to give you an idea of the Soku's size:

Dimensions
Span: 47.97m 157.4ft
Length: 37.70m I23.7ft
Height: 12.55m 41.2ft
Wing area: 289.95m2 3,121ft2
Wing loading: 156.72kg/m2 32.1 lb/ft2

Weights
Empty: 26,405kg 58,213lb
Loaded: 45,550kg 100,420 Ib
Useful load 19,095kg 42,097b

Performance
Max speed: 470km/h 292mph at 5,000m at 16,404ft
Cruise speed: 369km/h 229mph
Landing speed: 144km/h 89mph
Range: 3,890km 2,417 miles
Climb: 11 min 30 sec to 3,000m (9,842ft)

Source:  Japanese Secret Projects: Experimental Aircraft of the IJA and IJN 1939-1945 by Edwin M. Dyer, III. Midland Publishing/Ian Allan Publishing, Ltd, 2009, p63-64.

The Grumman A-6E TRAM: Making the Intruder More Lethal

The patch worn by A-6 Intruder crews. Note the radar and TRAM sensor symbolism

The main variant of the Grumman A-6 Intruder to fight in the Vietnam War was the first production version, the A-6A. The next two variants, the defense-suppression A-6B and the night attack-optimized A-6C, were just modifications of the basic A-6A variant and both the B and C versions served in only small numbers given their specialized roles. The next variant was actually the tanker version, the KA-6D. With the experience of combat, the Navy went ahead with the A-6E variant in 1968 which improved upon the deficiencies of the A-6A and replaced many of the 1950s-era systems with more modern equipment. With combat experience in the skies of Southeast Asia and over ten years of technological advancements, the A-6E was a major upgrade in capability, reliability and maintainability over the A-6A, with newer engines, a digital nav/attack system, a single multi-mode radar (the A-6A had two radars, which is why the Intruder had such a portly nose), and built-in test equipment that allowed the bombardier/navigator (B/N) to test the avionics before takeoff. On 22 September 1972, VA-85 "Black Falcons" embarked aboard the USS Forrestal were the first unit to take the new A-6E on an operational cruise. 

However, the navigation system of the new A-6E proved to be a weak spot and a few short years after the A-6E deployed with the fleet, CAINS (Carrier Airborne Inertial Navigation System) was added to the Intruder. Using the Litton AN/ASN-92 which was the same INS system used on the Grumman F-14 Tomcat and Lockheed S-3 Viking, an Intruder B/N literally plugged the aircraft's INS into the aircraft carrier's navigation systems to get a quick and very accurate initial fix before departing on a mission. But the most dramatic improvement to the capabilities of the Intruder came about at the same time as CAINS. At the time, there were a number of Intruder combat veterans assigned to the Office of the Chief of Naval Operations (OpNav) and with the Naval Air Systems Command. They spent their time getting upgrades and improvements pushed out to the Intruder fleet like CAINS.

A-6C TRIM. Note the prominent ventral gondola for the sensor.

One of the officers, Lieutenant Commander Lyle Bull, was working in the Aircraft Requirements Directorate of OpNav and decided to see what he could do to make the Intruder a full-capability all-weather/night attack aircraft that they had always dreamed about in Vietnam. During the war twelve A-6As were converted into the A-6C which had a large ventral gondola that housed the TRIM (Trails/Roads Interdiction Multi-Sensor) unit that had a FLIR and low-light TV (LLTV) unit for night attack missions over the Ho Chi Minh Trail. Large and aerodynamically bulky, TRIM also suffered from the relatively primitive state of the art in sensor technology at the time. Bull decided that TRIM was a good starting point for an improved system for the A-6E. This improved system became TRAM- Target Recognition Attack Multi-Sensor. In his position with OpNav, Bull had seen the state of the art in infrared technology and made the astute observation that there was space in the Intruder for an internal installation- because, as he put it, "Pods and sailors are not compatible". In the A-6A there was a separate search radar and a track radar in the portly nose- with the A-6E, a new Norden unit combined the functions into one radar and there was now space where the track radar used to be in the lower portion of the nose section. Bull had figured out that a 400-pound installation would fit perfectly into the space. 

In briefing his superiors on what TRAM could do for the A-6E, he pointed out that unlike TRIM which could only search and identify targets, TRAM would also incorporate an internal laser designator to mark targets for the new generation of laser guided bombs under development. Combined with the advances in sensor technology, an A-6E TRAM had a drastically improved bombing accuracy with miss distances of less than 10 feet, while today routine, such accuracy was stunning in the 1970s. However, in the lean funding environment following Vietnam, money for the R&D for TRAM had to be raided from other Naval Air Systems Command programs. Bull's superior, Rear Admiral Donald Davis, authorized $15 million in initial funding with the warning that the funding came from other programs which mean Bull wouldn't be liked- "They'll be after your ass, so watch yourself", he warned. 

A-6E TRAM prototype. Note the compactness of the installation.

Both Hughes and Texas Instruments agreed to develop competing designs for TRAM and Grumman readily agreed to handle testing and integration. Both systems were broadly similar differing in sensor details. TI had the advantage having developed the TRIM sensor during Vietnam- however, Hughes' design proved to better in testing and it was selected for the TRAM contract. As part of the TRAM integration, Grumman took the opportunity to upgrade the radar so it was better integrated with the TRAM sensor along with a new intertial navigation system. TRAM B/Ns would remark on the ease and simplicity of operating the laser designator. 

The A-6E TRAM prototype made its first flight at Grumman's Calverton facility on Long Island on 22 March 1974. With only a year of systems integration testing, Bull's system proved to be winner and the Navy began to procure TRAM units for the A-6E fleet. The first production A-6E TRAM flew on 29 November 1975 with VA-42 "Green Pawns" at NAS Oceana getting the first examples on 1 December 1975. Combined with CAINS, by the early 1980s the entire A-6E fleet was flying the most lethal Intruder variant yet and by that time, a Direction and Ranging Set (DRS) and Airborne Moving Target Indicator (AMTI) were added to the aircraft. This all made the A-6E TRAM Intruder the most accurate all-weather attack aircraft in the fleet if not all of the US forces. It would culminate with the A-6E TRAM being responsible for 85 percent of all the laser designations and LGB drops during Desert Storm. 

Source: Intruder: The Operational History of Grumman's A-6 by Mark Morgan & Rick Morgan. Schiffer Publishing, 2004, p131-133.

Weighing only 55 lbs and about the size of a bass drum, the first geostationary communications satellites were the three Syncom satellites built by Hughes in the 1960s. Syncom 1 was launched on 13 February 1963 atop a Delta rocket from Cape Canaveral, Florida. All communications with Syncom 1 were lost when the apogee kick motor was only a second left from its 22 second burn to put it into geostationary orbit.

Syncom 2 was launched 26 July 1963 and was more successful. After a month in near-geostationary orbit with the USS Kingsport in Lagos Harbor, Nigeria, acting as a relay, Syncom 2 allowed President John F. Kennedy to speak by phone to Nigerian Prime Minister Abubaker Balewa from the White House in the first satellite conversation between two heads of state.

Syncom 3 was launched a year later and reached true geostationary orbit in time to broadcast the opening ceremonies of the 1964 Summer Olympics in Tokyo in the first continuous satellite TV broadcast across the Pacific. Syncoms 2 and 3 would operate until 1966, providing telephone service home for US troops in Vietnam.

The Syncom ground station dish was 85 feet across, cost millions of dollars and only had a single channel. Today's home satellite dishes are less than 2 feet across, cost under $100 and provide over 300 channels.

Source: Air & Space Smithsonian, September 2009. "Spin Doctors- How three engineers launched the comsat revolution" by Guy Gugliotta, p25.