Lesson 6 - Stalls.

10 July 2011   cancelled due to weather.

17 July 2011   Warrior III - VH-TXH

In 12 years of paragliding I'd never intentional stall my paraglider - probably because it collapses into a ball above your head and all hell breaks loose.  But now I had to make a plane stop flying and fall out of the sky.

My lesson is booked for Sunday 10th July but when I wake up and look out the window and it looks like the weather gods have decided I have to wait another week. My first cancelled lesson. 

Stall by Jetfxer

The next week comes around and the weather is looking much better but when I arrived at the airport, I find out Jason is running very late and won't be able to make my lesson.  I'm starting to think this was not meant to be. 

Luckily Fenella has some time before her first lesson, so I’m not going to get out of it - to be honest I was hanging out for a fly. So once again I’m with a different instructor.  

We take-off and head to the training area and it’s time. 

• HASEL check – Height, Area, Secure, Engine and Lookout,
• Carb heat on, Power to idle,
• Keep pulling back to try and maintain height until,
• The stall alarm starts going off, Carb heat off,
• The buffering starts then plane stops flying and nose drops
• Let it drop, apply full power, keep it straight with the rudder
• As the speed builds level out and return to Straight and level flight.

THAT’S IT??? Clearly I’ve seen too many airshows. While I wasn’t expecting a hammer head stall, I was expecting a bit more of a reaction.

The next few were much the same non-event.  We did have one small wing drop but had it quickly under control with opposite rudder.  All in all, another fun day of flying.

Piper Warrior III VH-TXH,  Flight Time 1.2hr (Total 6.7hrs)

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Technical stuff

•      HASEL check – 

o   Height - 3000Ft+

o   Area – No over build up areas, preferably lots of paddocks,

o   Secure – Hatches, Harness and any loose items away,

o   Engine – Oil Temp & Pressure, Fuel Pressure, fuel pump on, carb heat on, and

o   Lookout 360^O clearing turn, (follow by 90^O turn after each stall)

• For the Warrior III VS₁ (Clean Stall Speed) = 50KIAS and VS₀ (Stall Speed with full flaps) =44KIAS
• The Stall angle of attack doesn’t change.  How the Stall speed does.
• Stall Speed is effected by

1.    Weight – VS₀ and VS₁ are measured at Maximum weight.  The stall speed will be lower when the plane is lighter.
              VS = √(current weight/Maximum weight) X VS_{(max weight)}

2.    Change in wing lift profile Ie Using Flaps, Slats, Damage to the wing, Icing etc.  As an example applying flaps increases the lift produced by the wing for the same angle of attack.  Icing on the other hand decrease the lift produced by the wing.

3.    Dynamic wing loading.  The stall stall increases by 2 main manoeuvres to watch out for  

a.    Turns In a turn the lift vector is banked, so more lift is required counter the weight of the aircraft.  Eg in a 60% bank the load factor is 2.  Increase in stall speed is √load factor ie. √2 =1.414.

b.    Drive recovery. Eg in a 2G pull out the load factor is 2 so once again increase in stall speed is √load factor ie. √2 =1.414.

4.    Use of Power. 

a.    Increasing power increases the airflow over the wing root and hence generates more lift.  It also acts at a lower angle of attack. 

b.    In a climb the power trust line is inclined and the vertical component therefore helps “lift” the plane.

• DON’T use the ailerons to pick up a Drop wing at the point of stall.  Using ailerons to try and level the plane will only increase the angle of attack of the dropped wing further.  This will further stall the dropped wing  making it worst.  Use the rudder instead.  The secondary effect of yawing is roll.
• As the Angle of attack increases the Centre of Pressure C_p moves forward.  At the point of stall it moves rapidly backwards, which causes the nose to drop (Which is a good thing)

Lesson 5 - Climbing and Desending Turns.

27 Jun 2011       Warrior III - VH-TYD

Besides learning how to do climbing and descending turns this was a lesson full of "first". 

 Up until now I've been flying first thing on a Sunday morning while is nice at quite at Moorabbin, but due to my daughter's concert I was going to be flying midday on a week day.   Flying Sunday morning has a number of advantages; 1) I can be back home again by 10:30 to spend the rest of the day with the family. 2) I rarely have to wait for other aircraft on the ground or in the circuit. 3) The weather has generally been better (winds lightly, less chance of rain). The only disadvantage has been the extended time in the run-up bay to bring the engine up to the correct operating temperature on cold winter mornings.

The second "first", was a different instructor.  Unfortunately my normal instructor was busy and I really wanted to fly, so I got him to suggest an alternative.  Collin is the head of training for the school so I knew I'd be in good hands.

Collin hands me the keys and maintenance release to TYD and I do to pre-flight walk around as normal.  This is where those "firsts" start to cause "differences" - the tanks aren't full. As I'm normally the first to fly the plane, the tanks are normally full.  This means I need to remember how to set the fuel volumes on the Avidyne EX5000 MFD.

I started her up and taxi to the run-up bay.   Time for the second difference - the engine is already warm. Instead of coming back to the engine checks (Mag, carb heat, & idle checks) after the oil temperature increases to 100C,  I get to do the run-up checks in the normal order.  

Time for the third difference - pre-flight safety brief and radio calls.  Up until this point this is something Jason has always done for me.  Collin seems a little surprised I haven't done them yet - something to follow-up Jason before my next lesson. So with Collin making the calls we taxi out and takeoff for the training area.

First up is Climbing turns.  I've actually been doing these ever flight already when I turn from upwind onto crosswind.  There are a couple of things to watch in addition to a level turn.  As I'm already climbing lift needs to be greater then weight and turning is going to make this worse.  So no more than a Rate 1 turn ie ~15 Deg  bank. The plane wants to increase the angle of bank due to the higher angle of attack and speed of the outer wing so I just need to make sure I'm maintain that bank angle with the ailerons.

After a couple of goes we try out descending turns.  As I'm now descending they is more lee way for generating the vertical components required to balance the weight of the aircraft and the therefore the bank angle can be high - up a medium (15-45 degree) turn.  The tendency for the plane to increase it's angle of bank is also reduced. While the outer wing is going fast it has a lower angle of attack and therefore the difference between the amount of lift is reduced.

After a bit of practice we head back to Moorabbin via Carrum.  Time for the last "difference" for the day - it's busy.  As we approach the reporting point there is another plane also making it's inbound call.  We are "Number 3" for 35L.

Another fun lesson.  Really enjoyed the "differences" and feel like the previous lessons are starting to come together.  I can now climb, descend, turn and fly straight and level.  If I put them all together I can effectively fly to the training area and back.  Once I've learnt how to land, make radio calls, and handle basic emergencies, I'll be able to go solo.  Next lesson - Stalls!

Piper Warrior III VH-TYD,  Flight Time 1.0hr (Total 5.5hrs)