Category 14 - Rotary wing aircraft - helicopter · MIL-STD-810H

2 tables appear under this heading.

1. PDF page 428

Helicopter	MAIN ROTOR		TAIL ROTOR
Helicopter	Rotation Speed 1P (Hz)	Number of Blades n	Rotation Speed 1T (Hz)	Number of Blades m
AH-1	5.40	2	27.7	2
AH-6J	7.95	5	47.3	2
AH-6M	7.92	6	44.4	4
AH-64 (early)	4.82	4	23.4	4
AH-64 (late)	4.86	4	23.6	4
CH-47D	Refer to TOP 01-2-603 (Paragraph 6.1, reference xx)
MH-6H	7.80	5	47.5	2
OH-6A	8.10	4	51.8	2
OH-58A/C	5.90	2	43.8	2
OH-58D	6.60	4	39.7	2
UH-1	5.40	2	27.7	2
UH-60	Refer to TOP 01-2-603 (Paragraph 6.1, reference xx)

MATERIEL	RANDOM LEVELS	SOURCE FREQUENCY (f_x) RANGE (Hz)	PEAK ACCELERATION (A_x) at f_x (GRAVITY UNITS (g))
General	W₀ = 0.0010 g²/Hz W₁ = 0.010 g²/Hz f_t = 500 Hz	3 to ≤ 10	0.70/(10.70 - f_x)
		>10 to 25	0.10 x f_x
		25 to 40	2.50
		40 to 50	6.50 - 0.10 x f_x
		50 to 500	1.50
Instrument Panel	W₀ = 0.0010 g²/Hz W₁ = 0.010 g²/Hz f_t = 500 Hz	3 to ≤ 10	0.70/(10.70 - f_x)
		>10 to 25	0.070 x f_x
		25 to 40	1.750
		40 to 50	4.550 - 0.070 x f_x
		50 to 500	1.050
External Stores	W₀ = 0.0020 g²/Hz W₁ = 0.020 g²/Hz f_t = 500 Hz	3 to ≤ 10	0.70/(10.70 - f_x)
		>10 to 25	0.150 x f_x
		25 to 40	3.750
		40 to 50	9.750 - 0.150 x f_x
		50 to 500	2.250
On/Near Drive System Elements	W₀ = 0.0020 g²/Hz W₁ = 0.020 g²/Hz f_t = 2000 Hz	5 to ≤ 50	0.10 x f_x
On/Near Drive System Elements	W₀ = 0.0020 g²/Hz W₁ = 0.020 g²/Hz f_t = 2000 Hz	> 50 to 2000	5.0 + 0.010 x f_x
Main or Tail Rotor Frequencies (Hz) Determine 1P and 1T from the Specific Helicopter or from the table (below).			Drive Train Component Rotation Frequency (Hz) Determine 1S from Specific Helicopter and Component.
f₁ = 1P	f₁ = 1T	fundamental	f₁ = 1S	fundamental
f₂ = n x 1P	f₂ = m x 1T	blade passage (BP)	f₂ = 2 x 1S	2^nd harmonic
f₃ = 2 x n x 1P	f₃ = 2 x m x 1T	2^nd harmonic	f₃ = 3 x 1S	3^rd harmonic
f₄ = 3 x n x 1P	f₄ = 3 x m x 1T	3^rd harmonic	f₄ = 4 x 1S	4^th harmonic