Hughes/MD 500

[Aged Beef]

From what I was told file.

During my short time there at MDHI 08-10 I was aloud to inform my maintenance student this: In 1976 the 369D was Certificated (500D). The helicopter was considerably difference from the 369H series. The 369D had 5 main rotor blades (vs4) a "T" tail (vs "V" tail, a stronger drive system, and a Allison 250-C20B engine (420 shp).The Max speed was increased to 175mph (vs 150mph)
(I was Told)The speed increase was the main reason for T Tail. Air going over the main rotor disc stablized by the T Tail. Keeps aircraft from rolling over forward in high speed. Note: 1975-76 was the early YAH 64 Apache prototype flight period, Look at a early photo of the Tail section. (uniformity in marketing T tailed aircraft? "Hughes") T-Tail went away on the Boeing AH64. I was told the V-Tail out performed the T-tail in most flight envelopes but yet the Spec-Op folks have retained a T-tail variant.I hope this helps, It may be all rumor and trash