June 01, 2011

Stalls and Spins

So, while flying yesterday (Which was brutal because it was 38 degrees with the humidity), I worked on Exercise 12 (Stalls) and Exercise 13 (Spins). I didn't get to take off because the crosswind was about 15 kts, but my instructor and I "co-landed", which was very cool :)

I'll start with discussing stalls. The stalls in a Katana are not very exciting (Anyone who've done stalls in the DA20, you know what I mean), but nonetheless aren't normal.

There are two main types of stalls, Clean Stalls (clean configuration, power at idle) and Dirty Stalls (landing configuration, very low power). To enter a clean stall, you first perform the HASEL check (for height, you want to be pretty high) and then two 90 degree clearing turns. Then, reduce power back to idle, and put the prop at the highest RPM setting. As the airspeed continues to drop, maintain back pressure on the stick. As the stall warning horn sounds, bring the stick back as far as it goes (this will feel very unnatural at first, but this is because the elevators aren't as effective at slow speeds). Keep maintaining directional control using the rudders, as the ailerons also aren't as effective. The airplane will continue buffeting (this is the stall), so to recover, lower the nose slightly below the horizon, and slowly increase power. Bring the prop RPM down to 2000 RPM, so that you don't overspeed the engine as you increase the power in a nose-down attitude. When the speed gets to an acceptable level, slowly level off and reduce power (you can also climb back to recover the altitude lost)

To perform a dirty stall, you also begin with the HASEL check and the clearing turns. You then reduce power to, in the Katana, about 16" Manifold Pressure, and as the airspeed enters the white arc, lower the flaps to the Landing setting. You then follow the same procedure as the clean stall. To recover, increase power to full, and retract the flaps. Like with the clean stall, bring prop speed down to 2000 RPM, and level off and reduce power, or climb back up to your previous altitude.

The spins, unlike the stalls, in a DA20-A1 are very exciting. You will only perform spins the same way as in a clean stall. After you do your HASEL check and clearing turns, you will begin to enter a clean stall. Your instructor will the induce yaw (usually to the left because that is where the aircraft usually tends to yaw because of other induced yaw), and the aircraft will pitch up and roll over, almost upside down, and you may lose some vision for a very brief period of time because of the G forces. You will then be spinning in the direction that your instructor induced the yaw. When your instructor tells you to recover, you apply full rudder in the opposite direction, but only until the aircraft ceases to spin. You will then be pointed almost directly at the ground, and then slowly pull up to recover from the dive (it won't feel very gentle, and you may lose some vision again :P). Then increase power to full, and reduce prop speed to 2000 RPM. When you gain airspeed again, you can either reduce power or climb to regain altitude lost.

SAFETY NOTES
-make sure you have tons of altitude available, because you will lose height very quickly in a spin (Make sure that your minimum recovery altitude is either 2000 feet AGL or the height specified in the POH, whichever is higher)
-many flight centres only allow stalls and spins with an instructor; make sure you know the rules of your club

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