LIFT COEFFICIENTS FROM SPIN SONDES-ROUNDS AH-126 TO AH-131 INCLUSIVE.
JOHNS HOPKINS UNIV SILVER SPRING MD APPLIED PHYSICS LAB
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Round AH-127 was fired to flip two 3 in x 6 in Gu-2 fins from -1 to 1 degrees at about 2 seconds after firing. The record showed clearly the reversal of spin at t 2.15 seconds and good measurements were obtained at w 0. Rounds AH-129 and AH-131 were flipped from 0 degrees to 2 degrees, and, therefore, no data exists for w 0. Accordingly, in the records for these rounds, no point exists at which the dynamic angle of attack is equal to zero. It is of interest to note that in all three rounds, the spin velocities reached higher values at subsonic linear velocities than at supersonic velocities. In one round, an increase of 75 was noted. This indicates that the lift tends to be reduced by reduction of the effective span of the wing at subsonic velocities and this is compensated for by increased angular velocity, i.e., if the relationship tan alpha rwv is valid, w must decrease with V, unless r itself is effectively reduced. In our rocket r apparently is reduced in the transonic region more rapidly than is V itself. Author