Inverted Spin

[djpacro]

Let's start with Bill Finagin's article in Sport Aerobatics Magazine of May 2007:

 

A good starting point is to master flying inverted. … next, try turning 90 degrees left and right and recovering straight ahead while flying inverted. Note here that to turn right (as viewed from the cockpit) you must lower the right wing towards the ground. This requires deflecting the stick to the left, which feels very unnatural. Next, try practicing simple, straightforward stalls while inverted.

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you are ready to progress to inverted spins. Hopefully they will seem less scary when considered simply as the next step in a progression of inverted maneuvers.

 

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It feels strange using the stick, because movement appears to be reversed … Don't get hung up on these facts; just continue and keep learning – arguing just stops the learning process.

 

A good technique that might help you to understand control inputs is to get a model or use your right hand to “hangar fly” the maneuver. If you always use your right hand as the “airplane” when hangar flying, you will see that your thumb is always going to point in the direction of a left turn. Simply lower your thumb toward the ground and turn in the thumb's direction. Why are these seemingly trivial items important? We will see ….

 

Now we are going to do our first inverted spin … in a Pitts S-2C.

 

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Once we are upside down we keep things straight and level … We reduce throttle … and increasing our angle of attack to maintain altitude. As we reduce power to idle and continue to raise the nose … Add a final full forward deflection of the stick as the stall occurs. It is exactly like the one we use when upright, except our senses are all 'screwed up” … As it stalls we push either the … rudder all the way to the firewall and keep it there.

 

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There are two perspectives, one from the cockpit and another from the ground. From now on, we will define an inverted spin as “inverted left rudder spin” or “inverted right rudder spin”. If you are inverted spinning with the left rudder pedal depressed to the firewall, you will look over the nose and see that it is moving to the left.

 

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So, before we go brain-dead from our new maneuver, we simply reverse the rudder, remembering that the nose always move toward too much rudder, and observe the nose to slow in rotation. As it comes almost to a stop, we now release the forward pressure on the stick and let it come back to the neutral position.

 

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Always do this training with an instructor in the airplane with you.

 

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you are pumping a lot of adrenalin in your body, and as a consequence you will most likely fly like a gorilla and overcontrol your airplane.

 

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Not purposefully, just brain-dumb! But the combination of incorrect stick and faulty rudder pedal pressure can create some quite interesting figures.

 

So, let's move along … the inverted flat spin. Just reading this will give some the “willies” …

 

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when the stall warning comes we will lead a slight amount of right rudder to ensure the right wing stalls first and we will rotate to the right. As the aircraft stalls we push full right rudder pedal as we continue to hold the stick fully forward. As the plane enters the spin … we will now move the stick to the full right forward position. Most of us will call this “in stick” position as the stick is on the inside of the rotation of the aircraft. … The right wing lifts and makes the right and left wings more horizontal to the earth as the plane rotates in a tighter (smaller) diameter, thus increasing the rate of rotation.

 

As you move the stick to the right, increase your throttle to cruise power … We are now in a fully developed flat spin. Now we will reverse the procedure to recover.

 

First we reduce the power; next we remove the ailerons by centering the stick while maintaining a fully forward deflection. We are now in the exact same position as we were in recovering from the previous inverted spin.

 

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We will discuss other inverted spins in a future article. … there are other techniques, and some contain things that will be done differently as you progress.

However, a few important things to follow up before we get too far.

[djpacro]

right rudder pedal ….. stick to the full right ….. Most of us will call this “in stick” position as the stick is on the inside of the rotation of the aircraft

The aircraft is yawing to the right and rolling to the left so Bill's reference to the rotation refers only to the yaw. Pilot's typically identify the direction of roll more easily than the yaw especially in a steep spin where the nose is low and there is a lot of roll in the motion. With the flat spin, the motion is largely yaw.The ailerons primarily act in the direction of roll so let's refer to aileron deflection with respect to the direction of roll. Actually, I had never come across Bill's “in stick” term until I read the article again for this series of posts.

 

The term “inspin” is more generally used. For example, from Rich Stowell's book The Light Airplane Pilot's Guide to Stall/Spin Awareness:

 

“In-spin ailerons may assist in the recovery from flat spins in some airplanes, and from spins in some fuselage-heavy, short-winged designs (in-spin ailerons may result in additional antispin yaw and a steeper spin attitude with a lower spin angle of attack). We must consider, however, the potential downside associated with using in-spin ailerons during recovery. For instance, it's possible to confuse the roll generated by the ailerons as a prolonged spin, even though spin recovery has already taken place. The airplane could transition abruptly from a spin into a high speed, high g, rolling spiral. Also, determining the direction of the roll and then applying the correct input may be difficult in an unintentional spin, especially during an inverted spin. (During an inverted spin, for example, the airplane yaws to the left from the pilot's perspective, but rolls to the right; therefore, right aileron becomes the “in-spin” aileron during an inverted spin to the left.)

 

Whether it is an upright or inverted spin, the term inspin aileron referring to the aileron deflection with respect to the direction of roll is consistent. An inverted flat spin with right rudder – inspin aileron to aid recovery is stick to the left. An upright spin with right rudder – inspin aileron to aid recovery is stick to the right. (of course, inspin aileron does not aid recovery in all types)