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The XW-35 was designed from the outset as a
megatons; the actual yield was 1.37 megatons with the shortfall due to poor burning of the secondary. By this time the Air Force had designated the XW-49, a simple modification of the TX-28 already successfully tested during the Redwing series. By August 1958 the first dedicated missile warhead design, the W-35, had been cancelled in favor of the W-49.