by Jan Meyer
A sub-formation of a large formation is called a "piece". Many sequential dives have pieces moving or turning with respect to each other. Piece flying is the result of cooperative efforts from everyone in the piece. Individuals within the piece have specialized flying jobs. These jobs relate to specific piece maneuvers. Successful piece flying is doing your job and letting others do their job.
To Move and Turn
A review of individual moving and turning, with advanced techniques, is required to fully understand how to move and turn pieces. Championship quality individual moving and turning is accomplished without any change in fall rate.
Each jumper can move in three directions and rotate about three axes, as shown in Fig. 1. (Several aerodynamic terms are also defined in the figure.) Once all jumpers on a dive have levelidity, relative motion in the vertical direction is undesirable. Relative horizontal motion in this "level plane" is acceptable. Rotations about two axes, roll and pitch, are generally undesirable in standard RW. These motions lead to barrelrolls, backloops or frontloops.
Fig. 1: Axes jumpers can turn about or move along.
Each jumper's nominal fall rate (for a given jumpsuit and weight) is determined by the position of his hip joint. The more arched the hip joint, the faster the fall rate. A jumper's fall rate should be compatible with everyone on the same dive. For a given dive, each jumper assumes a nominal fall rate by adjusting his arch. Each jumper should be able to keep his body between his shoulders and knees in the same position in order to maintain levelidity. Adjustments in an arch indicate that the fall rate of the dive changes. The rest of a jumper's body is used to move and turn. The control surfaces are each jumper's arms and legs below the knees. These control surfaces are also used to balance any turns or movements induced by head movement.
Motion in the vertical direction is accomplished by adjusting the hip joint. Twists at the waist are undesirable, since they will induce a turn with a change in fall rate. Jumpers should keep the same arch and refrain from twisting at the waist in order to maintain levelidity.
Level Plane Translation
Lateral motion can be side to side or front and back. Any combination can be performed too. The method is to tip slightly in the direction of motion. To move forward, a jumper's shoulders need to be lower than his knees. A jumper can accomplish this by extending his legs, moving his arms further aft or a combination of both motions. To slide to the right, a jumper must make the right side of his body lower than the left side of his body without changing his arch or twisting at the waist. A jumper can easily accomplish this by extending his left arm, drawing in his right arm and pushing both legs to the left, Fig. 3. Similar types of body movements can be described for all other motions in the level plane. (Readers interested in these details should call or write SPSJ for more information.)
Level Plane Rotation
Jumpers perform effective turns by pushing in one direction with one side of their body and pushing in the opposite direction with the other side of their body. (In physics, this is called a couple.) A jumper should push to the left with his arms and to the right with his legs to turn right and pivot about his center of gravity, see Fig. 2. (Coordinated turns done by extending legs, as described in SPSJ V2, #1 "The Helicopter Maneuver", tend to move a jumper about a circle as he performs his turn, see Fig. 2a. This article is on advanced techniques, not beginner level methods.)
Extension to Piece Flying
Jumpers flying a piece should consider the piece as a big jumper. Each jumper then has the role of a part of the big jumper. Jumpers should tip the forward part of the piece down, relative to the aft part of the piece, to make it move forward. Left or right slides are accomplished by tipping the proper side of the piece. Turns are accomplished by having jumpers on opposite sides fly in opposite directions.
To Turn a Diamond
A diamond is a very common 4-way piece that is rotated in large sequential dives. Each slot on the diamond has a distinct job in turning the diamond about it's center. There are three tasks to perform while turning the diamond. First and foremost is to maintain levelidity. The second is to maintain proximity and the third task is to maintain synchronicity.
Levelidity is accomplished by keeping the same arch position throughout the turn. Jumpers who perform maneuvers by dropping their knees change their arch and thus change the fall rate of the diamond. Jumpers should perform the aerial maneuvers with the same arch position.
Proximity is accomplished by ensuring that the side of the diamond closest to the large formation's center point is slightly lower than the side of the diamond furthest from the large formation's center point. This keeps the small diamond driving towards the center point. Proximity is lost when the side of the diamond furthest from the center point is lower than the closest side. The diamond tends to slide away from the center point of the large formation. Proximity may be enhanced by looking towards the large formation's center point at all times. The side of the diamond furthest from the center should be higher than the closest side.
Synchronicity is accomplished by coordinating the turns of more than one diamond. One diamond should be designated as the pace-setter. All other diamonds should match the turn rate of this diamond. The wings from each small diamond should pass closest to the center point at the same time. Likewise, the tails and other wings should pass through the center at the same time. The points should return to the center at the same time too.
Individuals within a 4-way diamond have different jobs or "flying tasks" to do in order to turn the diamond. Suppose the diamond is to be turned to the right 360�. The point slides to his right throughout the entire turn. The right wing backslides throughout the entire turn. The tail slides to his left throughout the entire turn and the left wing moves forward throughout the entire turn. These motions are shown in Fig. 4. The combination of these movements turns the diamond about it's center point, similar to the motion of a pinwheel.
Diamond right turn:
Jumpers who try to do individual turns, end up misaligned with the diamond formation, as shown in Fig. 5. They end up out of their slot, even though grips may still be maintained. The small diamond formation will have lots of tension in all grips and it will be harder to maintain levelidity, proximity and synchronicity.
Improper diamond right turn:
To Turn a Sidebody
Sidebody docks are common pieces to turn in many dives. The easy slot is the one with no grips, #1 in Fig. 6. The harder position is the one with the grips. #1 extends his legs and draws his arms backwards as #2 shifts towards the knees of #1 and pushes his legs in the direction #1 is facing. Keep arching and avoid twisting at the waist.
Sidebody piece turns:
The Secrets of Piece Flying
There are no secrets to flying pieces. Physics is physics! Whether it's applied to an individual jumper or a group of jumpers, the same laws govern the motion.
Mechanically, jumpers have an easier task when flying in a piece than when flying as an individual. As noted in the explanation on diamond turning, each jumper only has to fly in one well defined direction to turn the diamond. However, a jumper must move part of his body one way and part of his body another way to do an individual turn.
Conceptually, piece flying is more difficult. The explanations of how to fly and turn pieces are usually skipped over in most dirt dives because it's hard to explain how to do it and what each jumper's job is in each slot. Make a point of determining the jobs of each person in the formation.
Originally published in Sport Parachutist's Safety Journal,
V2, #3 Jan/Feb. 1990.
Dedicated to enhancing sport parachuting safety by disseminating information about equipment, environments and human factors.