Flying 'Tweety-Bird' - Part One. Introduction to "Low Performance" Aircraft

I decided to jump in and try my hand at the Aero Club's other recreational aircraft, a CA-25N Gazelle - aptly named Tweetie.  You'll see why!  There was no particular reason, just that the Tecnam was out for a couple of days with maintenance and I thought it would be interesting to be qualified to fly either.  This aircraft falls under a different category than the Tecnams or the Jabiru.  It's considered a low performance aircraft.  What is low performance, you ask?  Any aircraft with a normal cruise speed of eighty knots or higher is considered high performance - everything below that is low. Tweety cruises at 70 knots.  What does this mean for a pilot?  Well, in RA-Aus terms, it is another qualification to add to my pilot certificate and will possibly open up to other aircraft in the future. 

 

Meet Tweetie!

The first thing I noticed when walking up to this new bird was that, aside from the cowl and the wingtips, it is almost completely a fabric-covered aircraft.  Wings, fuselage, tail feathers - all fabric.  Even between the two struts that go down to each main landing gear has fabric stretched between.  The CFI took me through a daily inspection.  There are a lot of connections and bolts to check.  Fortunately, most of them are on the outside of the aircraft, so they are easy to inspect.

The other big difference from my previous aircraft is - no flaps.  None.  This leaves the space for full-span ailerons!  These are in four segments and I imagined that they would give her a very sporty roll rate.  Other notable aircraft with full span ailerons are designed for aerobatics, like the Extra 300S.  I don't think for a moment that this is in the same category, but it is fun to dream!

The Gazelle is powered by a Rotax engine, similar to the Tecnam - although this is the smaller engine producing 80 horsepower, versus the Tecnam's 100 horsepower variant.  With the empty weight similar to that of the Tecnam yet more drag, power management is important.  Especially on climb-out. I was warned that some new converts to the aircraft get tricked by the sloping nose, raise it to the horizon and run out of speed very quickly!

The cockpit is very small!  It's so small, that I didn't need any pillows (err... height deficit rectification devices) or anything to reach the rudder pedals - even though the seat doesn't move!  Speaking of rudder pedals, see the loops up above them?  They are the brakes, just like a GA aircraft.  That part will take some getting used to, as my muscle memory is trained to grab a lever in the centre of the cockpit to actuate the brakes.  Apparently this aircraft also has a wishy-washy control on the ground.  "The hardest thing about flying this aircraft is taxiing it!", says the CFI.

When we got in and started up, apart from all the switches and buttons being in different spots, it was pretty straight-forward.  I warmed the engine for a bit while I went over emergency procedures in my head.  After a moment, it was warm enough to complete a run up.  Here came the next difference!  It has a sprung throttle - if you let it go without tightening the friction nut, it slowly moves to full throttle!  Was a bit of a shock when taxiing I took my hand off momentarily to hit a switch!   Wheee!

We wallowed over like the QE2 and lined up on 18. The CFI gestured that I should do the take off.  With that, I poured on the coal and we started to move down the runway.  First to the right, then to the left, right, left a bit, left a bit more, right again, left, right.  Finally there was enough speed and airflow over the tail feathers that I could raise the nose and have better rudder authority!  Not long after that we were climbing out at the leisurely speed of 60 knots indicated.  As I turned crosswind, the reality of flying a low-inertia aircraft set in.  At this speed, the crab angle to lay off the moderate wind was far more than I'd ever need to in the Jabiru or the Tecnam.  I departed the circuit and continued our - err - deliberate climb out to the training area for some upper airwork.

The trip out to the shores of Lake Burrumbeet took a while at this pedestrian speed, but it is not what this aircraft is designed for!  I looked out the window on my left and my eyes made their way down to the ground.  It wasn't long before I realised that I was looking almost straight down!  The door is see-through right to the bottom and bulges out a little - which means you can see the main landing gear, and also how slow your groundspeed actually is!

We completed some steep turns, which were fun because the clear panels above our heads mean we once rolled over in to the turn, I could see into the turn through the roof!  The turns were fairly easy, but did need quite a lot of rudder in and out of the turns to counteract the considerable adverse aileron yaw from those large control surfaces.  Stalling was next.  This is pretty-much a non-event in the Gazelle.  It takes a lot to get the nose up high enough, and then it doesn't actually stall... It just mushes along in a slight descent.  Now we got up to the real stuff: Side-slipping!  Having no flaps to steepen a descent, this aircraft is very good at this manoeuvre.  The large rudder and square fuselage make it quite effective.  Manny chose not to teach me this in the Jabiru because the slender, round fuselage does not lend itself to the sideslip.  Plus, it has flaps.  The CFI got me to sideslip left and right, moderately at first - then as much as I could manage!  It is a strange feeling to have the world come at you from the side window!


I then did a practice emergency glide and it was time to head back to the circuit for a couple of touch and goes. One advantage of a slow flying aircraft is that you have plenty of time on downwind to complete your checks - handy when you're still getting the feel for an aircraft!  The Tecnam was the opposite.  Downwind was over in what felt like no time at all!  I joined mid-downwind from 45° and completed the circuit.  I flared a tiny bit higher than I wanted to, and as a result landed a little harder than I'd like.  It is nothing that the strong undercarriage couldn't handle, though!  I resolved to do a better job the next time around.  

As we got most of the way downwind, we heard another aircraft (a rather speedier one, too!) announce that they were joining mid downwind.  My instructor said, "He'll catch up to us in no time.  No matter, let's turn base here and do a glide approch."  Cool. In my mind I was thinking that the aircraft would sink like a stone, so I kept the aircraft close to the airport.  It actually glides fairly well, and as a result I had to aggressively side-slip almost all the way to the flare.  Awesome fun!

I taxied back to the hangar, taking my hand off the throttle momentarily to switch various switches off.  Each time I did, I'd forget to nip the throttle friction nut tight and the spring would start pulling the engine towards full power.  I'd catch it before we sped up too much, but it certainly did keep me on my toes!

This introduction flight was fascinating.  The aircraft is similar enough that it doesn't feel too foreign, but it certainly is different enough to require significant forethought on my part!  I think I will continue with the other part of the conversion later when I have a chance.  It certainly is not a cross country machine, but it would be a great plane to jump in and do some circuits, or even a leisurely local scenic flight.