Inverted Spins

CHAPTER ONE

T-34C OUT-OF-CONTROL FLIGHT

WARNING

Application of power when not actually in a Steady-State Spin will

result in a rapid increase in rate of descent and airspeed.

102. INVERTED SPINS

Inverted spins are an interesting and spectacular realm of flight; a realm with which most pilots

are unfamiliar. Aerodynamically, the inverted spin is quite similar to the erect spin, since the

conditions required to enter an inverted spin are:

A stall at negative AOA, and

Yaw.

An inverted stall is more difficult to enter than an erect stall, although it CAN be done either

deliberately or inadvertently. In some aircraft, elevator authority is insufficient to induce the

negative load factor required to stall in level, inverted flight. However, inverted stalls can be

achieved in nose-high, slow airspeed, and inverted flight. For example, the T-34C can enter an

inverted stall from an inverted, 30 - 40 degrees noseup attitude by applying full forward stick.

Naval Air Test Center (NATC) evaluations of the T-34C spin characteristics revealed that while

recovery from an inverted spin was easily accomplished, the spin itself proved to be very

disorienting to the pilot. For this reason, the T-34C is not cleared for intentional inverted spins.

Disorientation experienced by the pilot during an inverted spin is primarily because the yaw and

roll occur in opposite directions. Pilots are more sensitive to motion about the longitudinal axis

than the vertical axis and are consequently more likely to interpret an inverted spin in the

direction of roll rather than the direction of yaw. Regardless of whether the aircraft is spinning

erect or inverted, the turn needle will always deflect fully in the direction of spin and is the only

reliable indication of spin direction.

In the T-34C Steady-State, inverted spins are characteristically flatter than erect spins with the

nose of the aircraft approximately 25 below the horizon.

Typical indications of an inverted, Steady-State Spin are:

Zero airspeed,

Two to three units AOA, and

Turn needle fully deflected in direction of spin.

The pilot will experience a load factor of negative one "G." In a standard inverted spin, the

average spin rate is approximately 140 per second and the aircraft will lose roughly 310 feet per

turn, descending at 8700 feet per minute (fpm).

INTRODUCTIONS AND SPINS 1-9