Archive for July, 2009

Oh boy, what a lesson. I think this has got to be the hardest thing I’ve done in a while – not because there was anything technically difficult about the flying but that there was so much stuff to remember. Climb speeds, power settings, flap settings (more about this one later!), radio calls and, of course, checklists. The wind didn’t help either – it was gusting up to 30 knots.

At least there was no crosswind, though. There are three types of climbs – a normal climb, best angle climb and best rate climb. A normal climb is a slow, but comfortable (for the passengers!), climb with a low rate of climb and high speed. The best angle () climb is the slowest climb, but at a high angle. This is used to clear obstacles at the end of the runway. The best rate () climb is a tradeoff between the two – giving best rate of climb and a moderate amount of airspeed.

Climbing is done by applying full power, a little rudder to balance the plane (with respect to the slipstream’s effect on the aircraft) and lifting off the ground when airspeed reaches 60kt. After liftoff, the aircraft’s speed and rate of climb is dependent purely on the nose attitude. Each aircraft has a specific and speed. In the case of a Cessna 150/152, these are:

= 55kt

= 67kt (approximated to 65kt)

= 70 – 80kt

For some reason, when I was practicing the best angle of climb, the aircraft’s stall warning sounded a number of times. Next time, I should really ask why that was happening especially given that the aircraft’s stall speed is 40kt (and I was nowhere near it). I suspect the winds would have had something to do with it.

Levelling off from a climb to straight and level is a little different from the Power, Attitude, Trim sequence that I had learnt previously. Because the aircraft is travelling at a lower airspeed, the first item is now Attitude, followed by Power then Trim. The reason for this is that, on full power, changing the nose attitude to straight and level allows for an increase in airspeed to compensate for the lower airspeed during the climb. Once the airspeed is closer to the normal cruise speed, power is then adjusted to 2300RPM (or otherwise) and control pressure trimmed out.

It’ll take me some time to remember these numbers, but hopefully I’ll get them at some point!

Descending was a little more fiddly. There are three descent configurations – the normal descent for when you want to have a gentle descent down to terra firma (usually when you have some distance from the airport), the approach configuration (short distances) and the glide (shorter still). Normal descent was fairly simple – P.A.T, 2000RPM and trim for 75kt. The other two types of descent were the fiddly ones. The approach configuration is 1600RPM, with two stages of flaps and trim for 70kt. As the RPM is dropping below 2000RPM, the carburettor heat must be applied (to prevent icing). Again, PAT is the sequence, after carby heat is applied. Glide configuration, same deal but the engine revs are set to idle and trimmed for 60kt (best glide speed). Without power, trimming is a bitch. In both the approach and glide configurations, the ideal altitude lost (as shown on the vertical speed indicator) is around 500ft/min.

Just for my own revision, descent speeds in a C150/152:

Normal descent – 75kt @ 2000RPM

Approach configuration – 70kt @ 1600RPM (+ carby heat)

Glide descent - 60kt @ idle (+ carby heat)

When practicing the approach configuration, I experienced my first equipment failure. It seemed as though as our flaps weren’t functioning as they were supposed to (two stages of flap only extended one stage, and three+ stages of flap fully extended the flaps). That being said though, having no flaps isn’t really an emergency – it’s just a lost of a luxury.

During this flight, I was able to test drive (I mean, test fly!) the LightSPEED Aviation QFT SOLO headset which I had already tried on the ground and found to be a really comfortable headset. There are some rather lengthy and indepth reviews floating around the internet and as a student pilot with only 2.6 hours of powered flying to my name, I am probably not in an authoritative enough position to write up a full review. However, I can and will comment that they are indeed a very comfortable headset to have worn for that (just under a full) hour, that I was able to hear ATC very clearly (a problem with the school-provided headsets and right on time for my first flight doing the radio calls!) with much of the engine noise cut out and that the microphone actually worked! For $299, I was very happy with this purchase.

Next lesson is on medium level turns – so until next time!

Key Moorabbin Tower Frequencies:

• ATIS – 120.9
• Ground – 119.9
• Tower East + Circuits – 118.1
• Tower West – 123.0

On start-up, listen to ATIS (120.9) – listen for:

• runways in use
• wind direction and speed
• cloud base and amount
• temperature
• QNH (air pressure)
• any special requirements
• ATIS code

Before taxi, switch to the Ground frequency (119.9), and listen for anything that may impact you.

On approach to the runway holding point, switch to the appropriate tower frequency (118.1 or 123.0). The call to tower then consists of:

• ‘Moorabbin Tower’
• Aircraft type, call sign
• Location
• Intention
• Dual or Solo flight
• Confirm receipt of ATIS code
• ‘Ready’.

For example – ‘Moorabbin Tower, Cessna BNM, Runway 35R, For Training Area, Dual, Received Charlie, Ready’.

The tower may then respond with three possible commands generally. These are prefixed by the call sign and may be:

• Hold Position (stay at the holding point)
• Line Up (move onto the runway, but do not take off)
• Clear for Takeoff (line up, and take off)

The command is then read back (as an action, ‘holding’, ‘lining up’ or ‘clear for takeoff’), suffixed by the call sign. For example:

Tower: ‘Bravo November Mike, Line Up’
VH-BNH: ‘Lining Up, Bravo November Mike’

For circuit operations only – make the call when downwind with call sign, followed by location and landing intention. For example, ‘Bravo November Mike, Downwind, Touch and Go’. Tower will respond with traffic information. If traffic is sighted, add ‘Traffic Sighted’ to callsign.

For arrivals (external or training area) – make call when over the airport’s two inbound points, Carrum or the old General Motors (GMH) factory, with ‘Moorabbin Tower’, type and call sign, location and altitude, ‘Inbound’, ATIS code. For example: ‘Moorabbin Tower, Cessna BNM, Carrum 1500, Inbound, Received Charlie’.

The tower will respond with communications similar to those below. The appropriate responses are listed below:

In both cases (circuit or arrival), once on approach to land, clearance from the tower for the type of landing will be given in the format: call sign, clearance. The response is the type of clearance suffixed by the call sign. For example:

Tower: BNM, Clear Touch and Go
You: Clear Touch and Go, BNM

After a full-stop landing and clear of the runway, change to the Ground frequency (119.9) and make the call ‘Moorabbin Ground’, Bravo November Mike.

Summary of Checks

On the Ground

• Prestart
• After start (ROSFARB)
• Taxiing
• Run-up (TMPFISCH)
• Line-up (PIST)

In the Air

After Landing

• After landing – (CFIT)
• Shut down – (BRAM)
• Switch off and secure aircraft

Read the rest of this entry »

Initially, this sounded like that the lesson (on the 12th of July) would be a pushover. Oh, boy, I was wrong.

It’s not too difficult to keep an aircraft flying straight and level once it’s at that point. What’s difficult, however, is being able to switch power settings and then being able to maintain that straight and level flight. I had a LOT of trouble with this. Not to mention the weather conditions – 15-25 knots at 330 (so, some crosswind for 35L/R) gusting to 30 knots. Needless to say, I didn’t do the landing today (although, it was quite nice on final and on flare).

Basically, there are four types of cruises: fast, normal, slow and precautionary. I can’t exactly remember the speed for these cruises (though I’m thinking it was 105, 90, 75 and 60 respectively), but the power settings are:

• fast – 2500 RPM
• normal – 2300 RPM
• slow – 2000 RPM
• precautionary – 2200 RPM, 1 stage of flaps

To maintain steady straight and level flight, one needs to maintain a constant amount of lift. The lift formula is:

where:

• is the lift force
• is the air density
•  is the airspeed (velocity)
•  is the surface area of the aerofoil (wing)
• is the lift co-efficient

The pilot can only influence three of these factors – airspeed, surface area of the wing (using flaps) and the lift co-efficient. However, in flapless flight, the pilot can not influence the surface area of the wings so this is ignored. Airspeed is correlated with the amount of power (using throttle) is applied. One component, according to the Thin Airfoil Theory, can be controlled by the pilot – the angle of attack. The TAT states that:

where:

• is the lift co-efficient
• is the angle of attack

This is, of course, a highly simplified lift co-efficient. It’s good enough for the purposes for piloting, but before you aeronautical engineers cry foul, I know that there is no mathematical relationship between lift and AoA (for some light reading on this topic, click here).

So what does this mean for the pilot? Basically, control of lift in an aircraft correlated as such:

If the pilot increases their airspeed, the aircraft will gain more lift and will subsequently climb if the angle of attack is kept constant. If the pilot decreases their airspeed, the aircraft will descend if the angle of attack is constant. So, in order to maintain level flight, the pilot will have to reduce the angle of attack at higher power settings in order to maintain constant lift and vice versa for lower power settings. This means that, at the fast cruise setting, the nose attitude will be above the horizon marginally. At the normal cruise setting, the attitude will be about 3-4 fingers below the horizon and further below in the case the slow and precautionary cruise settings.

To change power settings and maintain level flight, follow this checklist:

• Power
• Attitude
• Trim

In order to maintain straight flight, the pilot needs to keep the ailerons level and the aircraft in balance. This is done by putting more pressure on the rudder pedal on the side indicated by the balance ball on the turn co-ordinator (below). S/he will also need to use a reference point in the horizon in order to maintain a good heading.

This lesson was challenging, as there was a lot to learn about how power settings influenced the flight of the aircraft – and how to manage it so that it is straight and level. Add some atrocious weather conditions and you have a party! But, I guess, the challenge of flying is half the fun of it. Unfortunately, I wasn’t able to get a lesson for next week due to the club going on a fly-away, so I have booked my next lesson (on climbing and descending) on the week following.

This is a bit of a retroactive post, because these lessons were almost a week ago (and that I only installed the blog tonight!).

My first lesson was on the 9th of July (which also happened to be 18 months since I started seeing my partner). This lesson or, more accurately, slightly extended trial introduction flight was on the topic of Effects of Controls in a Cessna 150 (VH-BNM). The ground briefing for this was markedly short, having already being familiar with these through my glider training. So, in this lesson I was taught how to taxi and was able to do it for most of the time during our trip to the holding point for 35R (there were certain points where my instructor, Arpana, took over).

Taxiing techinque is something I really need to work on, I’ve found. It’s pretty much a case of keeping a good lookout (and plenty of clearance for your wings!) and putting on some throttle so that we get some momentum, and cutting it back slightly once moving. From there, I need to use rudder and a bit of differential brake to turn and stay on the yellow taxi lines.

Once at the holding point for 35R, Arpana took over and lined us up for takeoff after the the appropriate radio calls. Then, she gave me the controls to takeoff. I was a little hesitant, but gave it a good shot. She, of course, talked me through it at critical points which was good. To take off, I put the throttle on at max power, used rudder to maintain centre-line (as much as possible) which was typically slight right due to the slipstream effect and started climbing at 60 knots.  She then talked me through getting to the training area. Once there, we did a bit of playing around on each of the controls to look at the behaviour of the aircraft given inputs to certain control surfaces.

This was only a short lesson – 0.6 hours – so we were soon headed back to the airport via Carrum inbound. Then, I was offered the opportunity to land the aircraft. On my first flight. “Oh dear”, I said to myself. I really had to think back quite a bit as to how I landed gliders and try to apply them as much as I could with this plane. The fact that she helped out by controlling the throttle for me was quite nice given that fact. The landing itself was, surprisingly, uneventful. I didn’t flare up as aggressively as I probably should have cause it was a harder than usual bump – but a good landing according to Arpana. I guess the training did kick in a bit .

What I found to be the key difference between landing a Cessna 150 and a glider (Blanik L-13) was the angle of attack on landing. Because the Blanik uses speedbrakes which creates serious drag, to maintain safe speed near the ground () of 70 knots you need to point the aircraft down by quite an amount – felt something like 30 – 40 degrees down, almost flying pointing to the ground. Landing the Cessna was not quite like that (not yet, at least!) and was just descending gently until the threshold. Otherwise, landing either aircraft was fairly similar…