on PPC airspeed which remains relatively constant  whether climbing, descending, or in level flight. When enough thrust is added to produce level flight,  the relative wind stream becomes horizontal with  the earth; the angle of attack and speed remain about  the same. Just as described in the  Pilot’s Handbook  of Aeronautical Knowledge for the airplane, thrust  equals total drag for level flight. [Figure 2-16] When in straight-and-level unaccelerated flight: LIFT (L) = WEIGHT (W) and  THRUST = TOTAL DRAG (D T ) The center of gravity ( CG) is the theoretical point  of concentrated weight of the aircraft. It is the point  within the PPC about which all the moments trying to  rotate it are balanced. The most obvious difference in  the center of gravity for a PPC is the vertical position  compared to an airplane, as it is much lower than the  wing. The  Pilot’s Handbook of Aeronautical Knowl- edge  accurately states the center of gravity is gener- ally in the vertical center of the fuselage. The same  is true for the PPC. However, the PPC wing is high  above the fuselage (cart) creating the unique pendu- lum effect flying characteristics of the PPC (which  will be covered in detail later). In a two-seat PPC, the second seat is typically behind  the pilot’s seat, and the center of gravity is usually  located directly over the rear passenger seat. There- fore, the center of gravity location does not change  significantly with or without a passenger. Fuel tanks  are typically located near the center of gravity so  any differences in fuel quantity will not significantly  change the center of gravity fore and aft with different  fuel quantities. When excess thrust is added to produce climbing  flight, the relative air stream becomes an inclined  plane leading upward, while angle of attack and speed  remain about the same. Just as described in the  Pilot’s  Handbook of Aeronautical Knowledge for the air- plane, the excess thrust determines the climb rate and  climb angle of the flight path. [Figure 2-17] Figure 2-17. Powered parachute in climbing flight.  Figure 2-16. Powered parachute in level flight.  Center of Gravity 2-8