Interstate TDR-1 assault drone

Of all the missions flown against Rabaul-or even throughout all of World War II- few were as unusual as the sixteen one-way sorties by unmanned “assault drones” in October 1944. Almost seventy years before the proliferation of unmanned aerial vehicles (UAVs) such as those used in the Global War on Terror, expendable radio-controlled drones were used to attack Rabaul. The TDR-1 looked conventional in almost every respect, with two inexpensive Lycoming six-cylinder engines, tricycle landing gear, and the capability to carry an external bomb or torpedo. A cockpit with flight controls was included for test or ferry flights, then faired over for the unmanned attack. Equipped with an RCA television camera in the nose, along with a gyro stabilizer and radar altimeter, the drones were flown by an operator in a stand-off TBM (General Motors-built) Avenger using radio control. Almost two hundred drones were manufactured, using lightweight tubular frames supplied by the Schwinn Bicycle Company, before the contract was cancelled. Most of the completed TDRs were shipped overseas with a unit called the Special Task Air Group (STAG)-1.

Before launching the drones against enemy targets, a live demonstration was conducted on July 30 for the benefit of the ComAirSols brass. Four drones carrying two-thousand pound general purpose bombs were directed by their control planes against Yamazuki Maru, a 6,500-ton merchantman beached on Guadalcanal. Technically the drones scored three direct hits, although one bomb failed to detonate. The fourth drone missed the superstructure by a matter of feet, exploding against the tree line. On the heels of that success, two missions were conducted against ships off southern Bougainville, along with other well-defined targets such as antiaircraft emplacements. Initial results due to malfunctions and equipment failures were disappointing. Nevertheless four separate strikes were flown against Rabaul by STAG-1 in October. Flying from Nissan in the Green Islands, each strike consisted of four drones for a total of sixteen sorties against Rabaul. A great majority either missed due to radio interference or malfunction, or crashed en route. (One of the wrecked drones was partially recovered by the Japanese, who discovered that the lightweight generator assembly and a sparkplug from one of the engines made an excellent cigarette lighter.) The last strike, on October 25, resulted in one direct hit on a secondary target, and a couple of hits on buildings near their intended target. The following day, the program was officially terminated.

On 27 September 1944, Special Task Air Group 1 arrived at Sterling Island, southwest of Bougainville, and Green Island with its Interstate TDR-1 assault drones. Pilots had flown these aircraft up from the Russell Islands. Then the manual controls were neutralized and a 1,000 pound general purpose bomb was hung under the fuselage. The aircraft were flown, under radio control from a following TBM, to targets in the Bougainville and Rabual area. Being guided by a television camera in the nose of the drone, the controller would dive the aircraft into the target – this at a time when few had even heard of television. While the results of these strikes were inconclusive, they did prompt Tokyo Rose, the Japanese propagandist, to broadcast stories about the American suicide pilots. Kamikaze strikes were yet to be conceived by the Japanese. After expending approximately 50 drones, the squadron returned to the United States. Little did any of us who watched these strange little airplanes skitter off the deck realize we were watching the granddaddy of the formidable cruise weapons of today.

Special Task Air Group One (STAG-1) was equipped with the Interstate TDR-1 pilotless assault drone.

This drone was a twin-engine, low-wing monoplane with a fixed tricycle landing gear and the ability to carry bombs. The aircraft was originally developed by the Naval Aircraft Factory in Philadelphia, Pennsylvania as the TDN-1 but because the factory was busy building the PBN Catalina, production was turned over to the Interstate Aircraft & Engineering Co. Although it had a cockpit for a pilot to test the aircraft, normal operation was for a TBF/TBM to control the drone via radio until it was over the target. The TDR had a TV camera in the nose and an operator in the TBF/TBM would control the path of the drone and aim it at a specific target.

5 October 1944

The USN’s Special Air Task Force (STAG 1), based on Stirling Island in the Treasury Islands, commences operations with Interstate TDR-1 target drones controlled from converted TBM-1C Avengers against Japanese targets in the southwest Pacific. Four Interstate TDR-1s, each carrying a 2,000-pound (907 kilogram) bomb, are launched against Japanese supply caves in the Keravia Bay, Rabaul, area of New Britain Island. One TDR hits in the vicinity of cave entrances; one misses the target area. Two are lost en route due to interference from communications frequency used by a motor gunboat (PGM) operating in the waters over which the drones fly.

9 October 1944

The USN’s Special Air Task Force (STAG 1) continues operations from Stirling Island in the Treasury Islands, Solomon Islands. Four Interstate TDR-1 target drones controlled from converted TBM-1C Avengers are launched against Matupi Bridge, Simpson Harbor, Rabaul, on New Britain Island. Antiaircraft fire, however, downs three of the TDRs; one is lost en route to the target.

15 October 1944

The USN’s Special Air Task Force (STAG 1) operations continue from the Nissan Island, Solomon Islands, as four Interstate TDR-1 glide bombs are launched against Matupi Island, Bismarck Archipelago, as part of coordinated attack by USMC PBJ Mitchells, F4U Corsairs and SBD Dauntlesses against Simpson Harbor Rabaul, New Britain Island. (Matupi Island is located in Simpson Harbor.) Poor picture reception and pilot error results in none of the TDRs hitting their targets.

17 October 1944

The USN’s Special Air Task Force (STAG 1) (Commander Robert F. Jones), based on Stirling Island in the Treasury Islands, Solomon Islands, continues operations as Interstate TDR-1 target drones are launched against Japanese installations near East Rabaul on New Britain Island. One of the four hits the objective; a second hits a target of opportunity; a third is lost due to the failure of a vacuum tube in the drone receiver; a fourth may have been shot down (light and inaccurate antiaircraft fire is noted).

18 October 1944

The USNs Special Air Task Force (STAG 1) operations continue as three Interstate TDR-1 drones are launched against a lighthouse on Cape St. George, New Ireland Island. None hit the target.

19 October 1944

The USN’s Special Air Task Force (STAG 1) based on Stirling Island in the Treasury Islands, continues operations with Interstate TDR-1 target drones. Two flights (one TDR each) are launched against Japanese gun positions west of Ballale. Ballale Island is a small island south of Bougainville. In the first, one drone misses its target during its run; in the second, the drone drops part of its ordnance [the two four-100-pound (45 kilogram) bomb clusters] on the target before it crashes.

20 October 1944

Special Task Air Group (STAG 1) operations continue from Stirling Island in the Treasury Islands. Three Interstate TDR-1 target drones controlled from converted TBM-1C Avengers are launched against Japanese gun positions west of Ballale Island located south of Bougainville: one is lost, one makes a hit with its bomb but crashes before it can be directed into its ultimate target (the beached Japanese freighter serving as an antiaircraft gun site off the Kahili Airfield on southern Bougainville and christened the “Kahili Maru”), the last achieves a bomb hit and crashes into “Kahili Maru” as planned.

23 October 1944

The USN’s Special Air Task Group One (STAG-1) operations continue in two missions; three TDR-1 target drones each guided by TBF-1C Avengers are flown against beached Japanese ships in Moisuru Bay and off the south end of the Kahili airstrip on Bougainville Island. In the first mission, one TDR scores a direct hit on “Kahili Maru” the beached Japanese freighter serving as an antiaircraft gun site off the Kahili airstrip; in the second, one TDR scores a direct hit on “Kahili Maru” while another hits a beached merchantman in Moisuru Bay.

25 October 1944

At Stirling Airfield (Coronus Strip) on Stirling Island in the Treasury Islands, In the Russell Islands, the last attack in a month long demonstration of the Interstate TDR-1 assault drone is made by Special Task Air Group (STAG-1), thereby concluding the first use of the guided missile in the Pacific. During the demonstration a total of 46 drones are expended, of which 29 reach the target areas: two attack a lighthouse on Cape St. George, New Ireland, Bismarck Archipelago, making one hit which demolishes the structure; nine attack anti-aircraft emplacements on beached ships achieving six direct hits and two near misses; and 18 attacked other targets in the Shortland Islands and Rabaul areas making 11 hits.

The TDR was a remotely-controlled aircraft — a cockpit was provided for ferry flights.  It was a clean twin-engined monoplane with fixed landing gear.  The TDR was fitted with a TV-camera in the nose, and could carry a bomb or a torpedo. The TDR was used in some attacks in the Pacific in 1944. Type: TDR-1 Function: attack Year: 1942  Crew: 1  Engines: 2 * 220hp Lycoming O-435-2 Speed: 225km/h   Ceiling:   Range: 685km Armament: 906kg

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