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APPENDIX D

Helicopter Characteristics

D-1. General.

a. This appendix discusses the characteristics of US Army aircraft (Chart D-1)

b. To efficiently load an AATF aboard helicopters, commanders and staffs must know the exact composition of the AATF, the essential characteristics of the types of helicopters to be used for the operation, and the methods of computing aircraft requirements.

c. Maximum ACIis are affected by altitude and temperature and will differ widely according to topography and climatic conditions common to specific zones or areas of military operations. ACLs will further vary based on the location of, approaches to, and exits from LZs; pilot proficiency; aviation unit SOP; type of engine in the aircraft; and age of both aircraft and aircraft engine. Therefore, two identical aircraft, of the same model and type, may not be able to pick up and carry identical loads.

D-2. References.

TM 55-450-15 provides detailed characteristics of Army aircraft, technical data, and guidance for computing aircraft requirements, and examples of detailed airloading and air movement forms.

D-3. Aircraft availability.

a. Aircraft availability is an overriding consideration in air assault operations. It is directly influenced by the adequacy and efficiency of maintenance and supply activities, and aircraft utilization and scheduling procedures, as well as by the distance of support units from the operating units.

b. Both the support and supported commanders should be aware that everyday use, over an extended period, of all available aircraft will result in a reduced mission availability rate for future operations. During periods of sustained operations, fixed-wing aircraft normally can maintain a greater percentage of aircraft availability for longer periods than helicopters. In the course of sustained operations, aircraft maintenance must be carefully considered and programmed so that heavy flying requirements will not cause a continual decrease in aircraft availability.

c. Supported unit commanders, staffs, and logistical planners must conserve the use of available aircraft by:

(1) Establishing acceptable availability rates prior to operational commitment.

(2) Establishing forward refueling and/or rearming areas to eliminate flying hours expended for those purposes.

(3) Utilizing surface means of transportation for logistical support whenever possible.

(4) Timely and coordinated logistical planning to ensure full utilization of all aircraft sorties and to avoid duplication of effort.

D-4. Capabilities and limitations of army aircraft.

a. Helicopters.

(1) Capabilities.

(a) Under normal conditions, helicopters can ascend and descend at relatively steep angles, a capability which enables them to operate from confined and unimproved areas.

(b) Troops and their combat equipment can be unloaded from a helicopter hovering a short distance above the ground with troop ladders and rappelling means, or if they can hover low enough, the troops may jump to the ground. The troop ladder can also be used to load personnel when the helicopter cannot land.

(c) Cargo can be transported as an external load and delivered to areas inaccessible to other types of aircraft or to ground transportation.

(d) Because of a wide speed range and high maneuverability at slow speeds, helicopters can fly safely and efficiently at a low altitude, using terrain and trees for cover and concealment.

(e) Their ability to fly at high or low altitudes and to decelerate rapidly, combined with their capacity for slow forward speed and nearly vertical landing, enables helicopters to operate under marginal weather conditions.

(f) Helicopters can land on the objective area in a tactical formation, LZ(s) permitting.

(g) Night and/or limited visibility landings and lift-offs can be made with a minimum of light.

(h) Helicopters flying at low levels are capable of achieving surprise, deceiving the enemy at the LZ(s), and employing shock effect through the use of suppressive fires.

(i) Engine and rotor noise may deceive the enemy as to the direction of approach and intended flight path.

(2) Limitations.

(a) The high fuel consumption rate of helicopters imposes limitations on range and ACL. Helicopters may reduce fuel load to permit an increased ACL. However, reducing the fuel load reduces the range and flexibility factors, which must be considered in planning.

(b) Weight and balance affect flight control. Loads must be properly distributed to keep the center of gravity within allowable limits.

(c) Hail, sleet, icing, heavy rains, and gusty winds (30 knots or more) will limit or preclude use of helicopters.

(d) Engine and rotor noise may compromise secrecy.

(e) Aviator fatigue requires greater consideration in the operation of rotary-wing aircraft than in the operation of fixed-wing aircraft.

(f) The load-carrying capability of helicopters decreases with increases of altitude, humidity, and temperature. This limitation may be compensated for through reduction of fuel load.

(g) Crosswind velocities above 15 knots for utility and 10 knots for cargo helicopters, and downwind velocities above 5 knots for either type of helicopter, will affect the selection of the direction of landing and lift-off.

b. Fixed-wing aircraft.

(1) Capabilities.

(a) Army fixed-wing aircraft can operate from relatively short LZ(s) if the terrain is fairly smooth and level.

(b) Fixed-wing aircraft have a greater range than rotary-wing aircraft and require less maintenance.

(c) On some fixed-wing aircraft, cargo can be transported as an external load suspended from bomb shackles on the wings and can be dropped with a high degree of accuracy from low altitudes.

(d) Landings and takeoffs at night or during limited visibility can be made with a minimum of ambient light.

(2) Limitations.

(a) Fixed-wing aircraft may require improved landing strips.

(b) Hail, sleet, icing, heavy rains, and gusty winds (30 knots or more) will limit or preclude use of these aircraft.

(e) A wind velocity of 8 to 10 knots affects the selection of the direction of landing and takeoff.

c. Special considerations. The capabilities and limitations of rotary-wing and fixed-wing aircraft are variable. Commanders of supporting aviation units provide specific data for each type of aircraft and operation.

D-5. Methods of determining army aircraft requirements.

a. Weight method (Chart D-1).

(1) The weight method is used when the total weight to be transported is the determining factor. However, this method is not accurate enough to compute requirements for units that must transport major items of equipment and also maintain tactical integrity. Aircraft requirements are determined by dividing the ACL (payload) of each aircraft into the total weight of the force to be airlifted. Whenever the weight method is used, care must be taken so that any one load does not exceed the ACL of the aircraft being used and that any one piece of equipment is within the size and weight limit of the aircraft. This method of aircraft estimation is not particularly accurate and should not be used below division level.

(2) Example of UH-1 using the weight method.

(a) Total weight to be transported 60,970 pounds.

(b) Allowable cargo load 1,700 pounds.

(c) 60,970 divided by 1,700 equals 35.8 or 36 UH-1s.

b. Type-load method.

(1) The type-load method is the most efficient method to be used in the conduct of air assault operations and in operational planning. Army aviation units are frequently required to support numerous major units operating over expansive tactical zones. Standardization of type loads within the theater of operation ensures responsive and effective airmobility with a minimum of time required for planning. The use of type loads does not limit the flexibility of a ground tactical unit to be airlifted. The type-load method can also be used at battalion and company levels to plan and conduct air assault and joint airborne operations.

(2) The use of type loads provides a drill-type SOP operation, thereby reducing the time required for planning and computation, and reducing the confusion and error common to air assault operations conducted with minimum advanced notification.

D-6. Sample load types for army rotary-wing aircraft.

a. UH-1. Maximum ACL for the UH-1 is 2,000 pounds. As fuel is reduced following the initial airlift, the troop load may be increased to eight or nine for subsequent lifts.

Cargo Weight (lbs) Total
(1) 7 personnel 1,680 1,680
(2) Bulk cargo 2,000 2,000
(3) 1 ea Mule (slingload) 900
Load on Mule 1,000 1,900
(4) 1 ea 1/4-ton trailer 565
Load on trailer (external load) 500 1,065

b. UH-60. Maximum ACL is 11 to 13 troops, depending on the aircraft seating configuration.

Cargo Weight (lbs) Total
(1) 11 personnel 2,640
1 ea 1/4-ton truck with trailer 3,500 6,140
(2) 7 personnel 1,680
1 ea M102 howitzer 3,195
40 rds ammo (A-22) 2,400 7,725

c. CH-47. Type-load data is based on an aircraft maximum gross weight of 33,000 pounds on a standard day at mean sea level. As density altitude increases, or when the aircraft is required to operate at higher altitudes, the payload is reduced accordingly.

Cargo Weight (lbs) Total
(1) 20 personnel 4,800
1 ea A-22 container (slingload) 3,000 7,800
(2) 8 personnel
Mules (loaded) 6,000 7,920
(3) 22 personnel 5,280
3 ea 81-mm mortars 282
150 rds ammo (slingload) 2,250 7,812
(4) 16 personnel 3,840
2 ea mortars 4.2-inch 1,200
100 rds ammo (slingload) 3,000 8,040
(5) 6 personnel 1,440
1 1/4-ton truck with 1/4-ton trailer 3,870
(slingload) 3,000 7,940
(6) 6 personnel 1,440
2 1/4-ton truck 5,200
1/4-ton trailer with load 1,000 7,640
(7) 3 personnel 720
1 M101A1 howitzer with sec equip 4,680
40 rds ammo 2,400 7,800
(8) 2 personnel 480
1 ea 3/4-ton truck 5,917
with cargo 1,500 7,897
(10) 3 personnel 720
1 1/4-ton truck with 1/4-ton trailer 3,870
1 Mule (loaded) 2,000 6,590
(11) 4 personnel 960
1 1/4-ton truck with MRC-95 radio 3,000
1 1/4-ton truck with 1/4-ton trailer 3,870 7,830
(12) 33 personnel 7,920 7,920
(13) 1 M102 howitzer 3,195
60 rds 105-mm ammo 3,600
Equip 430 7,225

d. CH-54. Type-load data are based on an aircraft maximum gross weight of 38,000 pounds on a standard day at mean sea level. As density altitude increases, or when the aircraft is required to operate at higher altitudes, the payload is reduced accordingly.

(1) Sample pod loads.

Weight (lbs)

(a) Mixed cargo

(b) 1 3/4-ton truck with trailer

(c) 150 rounds 105-mm ammo (boxed)

(d) 7,200 C-rations, individual

(e) 67 troops at 240 lbs ea

10,000

8,000

17,000

12,550

16,080

(2) Sample 4-point slingloads.

Weight (lbs)

(a) 2 1/2-ton truck

(b) Road grader (front see)

(c) Road grader (rear see)

(d) HD6 Bulldozer

(e) Personnel carrier M113

13,000

9,000

14,000

16,000

18,000

(3) Sample single-point slingloads.

Weight (lbs)

(a) 4,500-gallon fuel bags

(b) CH-47 helicopter minus engines and blades

(e) CH-34 helicopter, complete

(d) OV-1 Mohawk

(e) 155-mm howitzer

(f) 100 rds 155-mm ammo

13,200

16,000

8,500

12,000

14,000

14,000

 



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