Hi folks
Well i have started the slow trip to renew my pilots license. I went up in a Cherokee 161 last weekend nad did some basic stuff like climbing descending steep turns just to get the feel for flying an aircraft again. yesterday was a more lessoney (is that a word?) exercise as we did the whole briefing before takeoff to discuss what we were going to do (in this case: stalls).
My instructor is a C-Cat who also works for Airways here in Christchurch New Zealand which looks after all the Air Traffic Control, maps, Flight guides, simulators, maintain airport equipment etc etc. Charles was a brilliant Instructor, easy to understand what he was trying to demonstrate and made me relax!
Here we are returning from our refresher lesson with Charles on the left. (I think the smile is because I didn’t kill him with my awesome flying skills!)
So this time we are in DUP the last Cherokee 140 still active with the club fleet. She flies really nicely and is quite quick (ie: not a dog like some of the ones we had on the line)
So stalls. For those going “so like a car stalls”. Um no. Stalling in an aircraft is basically making the aircraft stop flying. Not like Wiley E. Coyote where he stops in midair and drops vertically! An aircraft needs three things to fly. Speed through the air, smooth air over the wing and thrust from the propeller (or jet engine if you are rich!) A fourth one that can vary (as they all can) is the angle of attack, basically the angle the wing is at to the airflow.
So to stall an aircraft is to stall the wing or kill the lift enough so the weight of the aircraft overcomes the lift forces.
So I hear you ask how do we do this. Think of a car going up hill. What happens if we take our foot off the accelerator/throttle/gas pedal? Yeah the car slows down and then stops going forwards. Same thing in an aircraft. If you raise the nose a few degrees above the horizon and hold it there and close the throttle (and hold the nose up) eventually the airspeed decays past the ability of the wings to generate lift. The result for the majority of aircraft is a bit of a shake as the smooth air over the wings gets all turbulent and then the nose pitches down. Not a death dive vertical down, just belwo the horizon. If you leave the throttle close and keep the nose down the airspeed builds up and hey you’re flying again. BUT if you are close to the ground you may hit it before you get flying speed again. Not good! So when you do stall you push the controls forward slightly (release the back pressure you had to keep the nose above the horizon) and apply full power.
This accelerates the recovery of the airspeed so you can then pull back and get a positive climb rate. This is a basic stall and after doing a few by the third attempt I was losing less than 100 feet in recovery.
The more dangerous stall is one where the aircraft yaws or angles slightly in the horizontal plane at the stall.(See diagram)
What can happen with this kind of stall is the aircraft drops a wing as the nose pitches down. If you leave it alone the aircraft will enter a spin and YOU WILL DIE! Ok that was for dramatic effect. Might be true if you don’t get it out of the spin but what the lesson does is what to do if the aircraft does drop a wing. Some may say well it’s a rolling motion just use the controls to lift the wing back up. No no no! The reason the wing has dropped is it has stalled BEFORE the other wing. If you try and lift the wing by using the ailerons it will make it worse! So what do we do. Rudder people rudder. This controls the yaw axis of an aircraft and in this case using opposite rudder with pick this wing up or at least stop it going down!
Now visually this can look bloody scary. Not helping was Charles pointing out that good old DUP had some differences in incidence between the left and right wing. I think about a degree different on the left wing. In the diagram you are looking at a wing end on.
And for those who have done wing drop stalls in a Cherokee the left wing drops. So good old DUP was an enthusiastic left wing dropper.
So how do we make this happen? From level cruising flight pull the power back to 1500 rpm. Apply full flap and hold the nose up. Most Cherokees have a stall warning light and buzzer to say “Hey dipstick you are about to stall!” If you release back pressure that will most likely prevent a stall but if you ignore it then “rumble rumble” and the nose pitches down.
However if you ignore it with full flap, 1500 RPM and then nudge the throttle up another 100 or so RPM as this stall warning goes off then POW! The left wing falls as the nose pitches down and you get this view:
I call this the “Brown Trouser” view and it’s pretty scary as the aircraft is starting to rotate. This is the point where you kick opposite rudder controls forward and full power. Level the wings normally once you have flying speed. Stall/spins have killed a lot of pilots and it’s usually when they are low and slow coming into land. I read somewhere if you do a single rotation spin you lose about 700 feet. If you are at 600 feet you hit the ground.
I found that I kept on trying to twist myself in my seat to keep myself to the horizon and the third one I actually imparted some aileron (as in rolling the wing up) which is very bad. I recall trying to overcome this by actually orientating my “worldview” to the top of the instrument panel and concentrating on the throttle, rudder and airspeed during the wing drop.
It was time to return to Christchurch and I actually managed a good crosswind landing on the main runway at the airport so that’s something else i haven’t forgotten how to do. Back in the flight office of the aero club we debriefed. Charles was full of praise for my flying ability, not that I’m the world’s best pilot (I’m not!) but because I flew so well after logging flight time of less than an hour over the last 12 years! Yes I’m rusty and have quite a bit of re-learning (and some new control zone and radio procedures to learn) but I could still remember most of the check lists. All I need to do is fly more often. After some discussion we thought the best way to do the BFR is book some holiday and take a few flights with a B-Cat Instructor. That was each flight can count towards the BFR (as you need a B-Cat to sign a BFR.) This is also the most cost effective as I’m not doing refresher flying and then doing a BFR which may need more than one flight depending on how well I fly.
Yeah cost. My little flight of 0.9 (54 minutes) Dual cost about $260. Gulp! So the quicker I can pass the BFR the quicker I can eat again!
I’ll try and update this again after my next flight. So watch the skies…I may be above you!!
Or maybe:
But probably: