Training the Best

I learned a new trick last week; spins. A spin is a difficult thing to explain because the only way I know how to explain it is in aviation language. It is a condition in which a stalled wing in combination with a yawing motion of the nose translates into a nose low autorotation.

For residents of North Carolina I can explain it this way: remember those seeds that fall from the maple trees? A spin looks just like that, the nose of the aircraft being the bulbous part of the seed and the tail being the wing part. There are two kinds of spins too; erect and inverted. In an erect spin the canopy is pointed towards the inside of the spin. In an inverted spin the canopy is pointed to the outside of the spin. We are not allowed to do intentional inverted spins because while you are in an inverted spin you experience negative 1 G, which is disorienting and may easily result in more negative Gs which really start to hurt as the blood rushes to your head. Remember hanging upside down from a tree? That's one negative G. Another concern is that the T-34C is only rated to -2.3 Gs while it can take 4.5Gs on the positive side.

So to get yourself into a spin, and yes we want to get ourselves into a spin; there is a fairly simple procedure. Starting at about 9,000' above the ground, you cut the power and bring the nose up to 30 degrees nose up. When you get rudder shakers (an electronic warning to the pilot that he is about to stall the plane) you lead with a little bit of rudder in the direction you want to spin. Soon thereafter the plane fully stalls and the nose starts to drop. Put your foot to the floor in the direction you want to spin and pull the stick back to your stomach.

Now the fun starts. The aircraft quickly starts to spin and descend towards the earth at 9-12,000 feet per minute (150 to 200' per second). The spin is not very violent in the T-34, it only rotates 120 to 180 degrees per second, but when you are trying to read gauges while you are being tossed around and the entire world is spinning past your cockpit it feels a lot faster.

We train to recover from spins because they are a very real possibility if we depart from controlled flight when doing aerobatics, but just as important is recognizing if you are really in a spin. If you are not actually in a spin and you apply the control inputs to recover from a spin you will only make the situation worse, so there are four instruments you have to look at first.

First and foremost is the altimeter. If you see 5,000' or less it's time to get the fuck out. You are descending at a very rapid pace and recovering from a spin takes a couple thousand feet. Also necessary to consider is how long it will take you to open the canopy, release your belts, disconnect your oxygen mask and radio cords, and dive clear of the aircraft. The manual says that this will take as long as 15 seconds and at 5,000' in a spin you only have 25 seconds before hitting the ground.

Next is the Angle Of Attack gauge; if it reads 30 units you are in an erect spin, three units and you are in an inverted spin.

After that is airspeed. 80-100 knots means erect spin, 0 means inverted. This is not an actual indication of your speed through the air; the error is due to the location of the airspeed probe; on the bottom of the wing. In an erect spin this probe isn't getting the normal amount of air, in an inverted spin this probe is shielded by the wing and seeing no airflow.

Then the turn needle, this tells you which way you are spinning. Which ever way the needle is pointing; apply full rudder in the opposite direction along with a bit of forward stick and the spinning should stop. Now you are nose down and the airspeed is building up quickly. Look up to the horizon, level the wings and pull. You'll pull between two and three Gs while recovering from this nose low attitude. Level the plane out, climb back up, and repeat. I actually really enjoy spins; they are a lot of fun. Some guys get sick during or after them and some just don't like them but I love them.

Most of the time you lose about 3,000' of altitude in a spin. If you start at 9,000' that means that you recover by 6,000'. This makes the instructors a little nervous and they are very quick to correct you if you are slow about applying the proper control inputs. I guess I would be too if my life was in the hands of a guy with less than twenty hours of flight experience.

So I'm back at it this week, hoping the weather holds out. I was supposed to fly this morning at 0700 but as I was driving in for my 0530 brief my instructor called and cancelled. I can't blame him, there were thunderstorms in the area and the radar showed no signs of clearing in the near future.

// posted by Josh @ 5/15/2006 11:59:00 AM