From Target: Rabaul: The Allied Siege of Japan’s Most Infamous Stronghold, March 1943–August 1945, by Bruce Gamble (Zenith, 2013) Kindle Loc. 7089-7112:
Throughout 1944 and well into 1945, bombers, dive-bombers, and fighter-bombers continued to hit Rabaul’s airfields to prevent their use; they kept a watchful eye on Simpson Harbor and attacked barges trying to resupply the garrison; they destroyed gardens to prevent the Japanese from growing food; and they strafed vehicles hauling supplies from remote caches. The number of sorties per month gradually declined, from a peak of approximately 2,200 in January 1944 to less than 300 by December. At the lowest ebb, an average of ten planes hit Rabaul every day, and the effort surged again in mid-1945 to more than five hundred sorties per month.
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 [Commander, Aircraft, Solomon Islands] 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 27, 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.