Schofields Flying Club Ltd - 1 Tower Road Bankstown Airport 2200
(PO Box 200, Georges Hall, NSW 2198 AUSTRALIA)
Phone: +61 2 9773 3611 Email: mail@schofields-flying-club.com.au
SCHOFIELDS FLYING CLUB NEWSLETTER - MARCH 2007
Schofields Formation in echelon right
Welcome to the March 2007 edition of Schofields News. There are the usual plus some new features - Ask the CFI by Pat Watson, X-File X072 (S.A.I. Ambrosini S.403) by Anthony Coleiro, Crosswind Operations by Pat Watson, Maui - Wowee! by Ken Raye, The Flight of G-EBMX by Peter Jones, London Calling Concorde submitted by Peter Blackbourn, and The Last Word from Latrodectus. As well, there's some of the usual administrivia that you've come to expect. So, read on and enjoy!
NEW MEMBERS FOR FEBRUARY: Welcome to Geoffrey Bedford, Jo Wong, Richard Daniel, James Robinson, James Chen, Heather Tyson, Malcolm Tyson and Pamila Wimalaratna.DUTY PILOT DRAW: The Volunteer Duty Pilot Monthly Draw for February ($50 free flying) goes to David Humble and Howard Elsey. The Club is appreciates the efforts our tireless band of volunteers generously gives in helping their Club and this is one small way of saying thank you!
THEORY TRAINING: The Club conducts training courses in preparation for the PIFR theory examination, and refresher training before attempting your AFR (aeroplane flight review). Here is your opportunity to get the very best tuition available in Australia, conducted by hand picked, specialist theory teachers. Next courses commencing mid-March.
FROM THE TOWER: The February-March issue of From the Tower, Bankstown's Air Traffic Control news circular, is now available (128kB pdf). It's aim is to provide the Bankstown aviation community with a bi-monthly source of news and information from an ATC point of view. You can download previous issues from our Downloads page.
ANNUAL GENERAL MEETING: The Club will be holding its Annual General Meeting on Monday 16 April 2007 at the Clubhouse. Come along and have your say!
DIARY DATES: The Club has a number of social and flying activities planned for 2007. You can check full details on our Coming Events page. Below is a summary of the programme for March and April 2007:
| Sat | 03 | March | NSW Interclub Competition Round 1 | Maitland |
| Mon | 19 | March | Committee Meeting | Clubhouse |
| Sun | 25 | March | Last Light Drinks | Clubhouse |
| Fri | 06 | April | Good Friday - Pulic Holiday | |
| Mon | 09 | April | Easter Monday - Pulic Holiday | |
| Sun | 15 | April | Club Competition | Bankstown |
| Mon | 16 | April | Annual General Meeting | Clubhouse |
| Wed | 25 | April | Anzac Day - Pulic Holiday | |
| Sun | 29 | April | Club Competition | Warnervale |
| Sun | 29 | April | Last Light Drinks | Clubhouse |
Patrick Watson
Last Newsletter I asked "at what stage of flight is lift the greatest". I added, "Give your answer in the context of a normal Airline flight". This question generated a lot of controversy. It is obvious that the question has a history, as indicated by comments on PPRUNE.
The answer is potentially quite simple but the arguments are complex. First of all we have to consider what is a "stage of flight". I would accept, take-off, climb, cruise, descent, approach and land are all stages of flight.Secondly a "normal airline flight" would preclude severe turbulence, steep turns (>25º bank), aerobatics, dive, steep descent, or any other regime out of the ordinary. Listed below are the most common answers received.
AT THE HIGHEST ANGLE OF ATTACK - AT THE STALL SPEED: Wrong answer. Not necessarily a stage of flight. Confusing CL, or coefficient of lift, with LIFT. LIFT considers coefficient of lift (angle of attack for a given wing shape), air density, speed and wing area.
AT THE HIGHEST SPEED: Incorrect. Interesting that this answer was also given by a professor at a top NSW University in the aviation department. He would accept no argument. Speed is only one component of lift. Maximum speed would be achieved when the nose is pointed directly at the ground. Not much lift is generated in that condition.AT THE POINT OF TAKE-OFF: Not necessarily correct. I would have accepted this answer with a correct explanation. As the aircraft accelerates down the runway, lift increases exponentially (as the square of the speed). As the pilot rotates, there is a significant increase in lift as CL or angle of attack is now added to the lift generated by speed alone. But not maximum lift. The weight of the aircraft is still partly supported by the wheels. At VLO (lift-off), the climb attitude has been established, the aircraft lifts off and commences climb. If the pilot aggressively rotates and puts a high load factor on the wing, then that could be an instant of maximum lift. However that is not normal - remember, I asked for an answer in the context of a normal flight. If the pilot gently rotates to the climb attitude, then lift transitions from "not much" to some value less than weight in the climb.
Rotating after take-off is no different to rotating in cruise from level flight to a climb. In order to prevent the tail scraping on the runway, pilots rotate gently, in the order of 3º per second to about a 10º pitch attitude.DURING CLIMB: Not correct. During climb, lift is less than weight. A quick study of the following diagram shows lift is less than weight in a climb. The four forces acting on an aeroplanes are vector quantities and have magnitude and direction. A measurement of the lift vector in the following diagram shows it is less than weight. The angles and lengths have been magnified for clarity, however the relationships are true. An aircraft does not climb because of excess or high lift. Rather it climbs because of excess thrust. In a steady climb the lift/thrust resultant must equal the weight/drag resultant. The greater the excess thrust, the greater the potential climb angle. As can be seen, lift is less than weight, it follows then that in steady cruise flight, when lift = weight, then lift must be greater than it is in a climb.
DURING A HIGH SPEED DESCENT: Incorrect. Lift is less than weight in a descent. Most airliners descend at zero thrust and rely on the forward component of weight to achieve a glide angle.
Surprisingly, the lift/drag ratio is of the order of 20:1. Adding thrust will decrease the glide angle or increase the speed. Speed on descent is usually limited by VMO. The following diagram shows the lift vector is less than weight. It is not drawn to scale as it would be impractical to draw a lift vector 20 times the length of the drag vector.THE CORRECT ANSWERS: Reference has been made in the above explanations to lift compared to weight. In a climb and a descent, lift is less than weight. Is there any time that lift is greater than weight? Perhaps. In cruise flight at a steady speed and constant altitude, lift equals weight. When is weight greatest? At top of climb. For example a Boeing B727-200 weighs about 80,000 kg at top of climb. Therefore lift equals 80,000 kg. That is a correct and acceptable answer for steady unaccelerated flight.
Is there any time when lift is greater than weight? Yes, in an acceleration. For example, during a turn or during a change from level flight to a climb or whenever there is a load factor greater than 1. This could also occur in turbulence. In the context of a normal flight, we can ignore severe turbulence and perhaps consider moderate turbulence at most.
During a turn, the load factor increases. Airliners turn at rate one, or 25º bank angle, whichever comes first. During a turn, lift is greater than weight. For example in a level 60º bank balanced turn, lift is twice the weight. However, the answer is to be in the context of a normal airline flight. Airlines do not normally exceed 25º bank angle or rate one turn whichever occurs first. In a 25º bank angle level turn, lift increases by about 10%. Therefore, a turn at top of climb would generate about 88,000 kg, whereas the same turn at the end of the cruise stage when the aircraft weighed typically about 70,000 kg, the lift would be about 77,000 kg which is less than top of climb level gross weight. Which all goes to show what a lousy question to ask a candidate at a job interview.
Sunset at midnight just north of the Antarctic Circle DEFINITIVE ANSWERS - in the context of a normal airline flight:
- at top of climb
- during a turn especially at top of climb
- during turbulence could be an answer. However it is transient in nature. Moderate turbulence increases the load factor - hence lift - by 30%.
THIS MONTH'S QUESTION: The next question is a lot easier. Again the first correct answer received together with a brief explanation gets points towards an end of year prize. Second and third also get points. The question: Consider this extract from a letter a pilot wrote home: "The sun setting directly ahead, confirmed my true track of 180º". Assume nil wind. What is the date?
Until next month, Happy Flying
Patrick Watson CP/CFI
X-FILE X072 - S.A.I. AMBROSINI S.403 DARDO - ANTHONY COLEIRO
S.A.I. Ambrosini S.403 Dardo The Italian S.A.I. S.403 was a refined version of the S.A.I. S.207 fighter, which had taken precedence over the earlier S.S.4 canard fighter (File X066 September 2006).
The S.403 differed from the S.207 in having a new wing profile, redesigned tail surface in which the angle of incidence was adjustable in flight, a redesigned rear fuselage, a fully retractable tail wheel and the internal fuel and ammunition capacities were increased.
Three variants of the S.403 were studied, a light defence interceptor, a general-purpose fighter and a long-range fighter. The difference in the variants being the configuration of the armament and the addition of underwing drop tanks for the long-range fighter, otherwise the aircraft were all exactly the same.
Anthony Coleiro The structure of the S.403 was strong and sturdy and it leant itself to dispersed mass production as the greatest possible use of wood was used and the designers made only limited use of strategic materials to.
The machine was powered by a 750 hp Isotta-Fraschini R.C.21/60 liquid cooled engine with a 3-bladed constant speed propeller.
The prototype was completed late in 1942 and possessed excellent handling qualities with a maximum speed of 628 km/h at 23,620 feet. In January 1943 an order was placed for 3,000 of these fighters, this order superseded the order for the 2,000 S.207 fighters. Only thirteen of these aircraft had been completed when the new order was placed.
Tooling up for this fighter had only reached the initial stages by the time the Armistice was signed and as a result, all work was terminated on the S.403.
ACKNOWLEDGEMENTS
- The Complete Book of Fighters - William Green Gordon Swanborough
- War Planes of the Second World War - Fighters Volume Two - William Green
Patrick Watson CONTINUED FROM LAST MONTH'S NEWSLETTER...
Legalities
Part of an ATIS report says "... Wind 270 degrees 15, gusting 25, all crosswind..." What is the average crosswind? If you answered 20 knots, you are wrong. The correct answer is 15 knots. The ATIS is reporting the average wind is 15 knots gusting to 25 knots. If your aeroplane's maximum crosswind component is 15 knots, can you operate with this crosswind? Some people will say "yes", and add that they will land and takeoff when it is not gusting.
The definitive answer lies in your Operations Manual. Schofields Flying Club requires pilots to observe the maximum crosswind component and do not take off or land if the crosswind component - including gusts - exceeds the maximum for the aircraft. By the way, we do not differentiate between "Maximum" and "Maximum Demonstrated" crosswind component. Should you take gusts into consideration? There is nothing in the regulations or orders. The only reference to wind gusts is in the AIP. See ENR 1.1 para 73.2.1: "Note Wind gusts must be considered when assessing alternate requirements."
| Wind Gust - definition |
| A sudden, brief increase in speed of the wind. According to U.S. weather observing practice, gusts are reported when the peak wind speed reaches at least 16 knots and the variation in wind speed between the peaks and lulls is at least 9 knots. The duration of a gust is usually less than 20 seconds. |
How do you determine the crosswind component for your runway?
The crosswind component for a particular runway at a particular aerodrome is only available via ATIS or a Take-off and Landing report. In all other circumstances, the pilot has to determine it himself.Many aerodromes have AWIS. (Automatic Weather Information Service). The VHF AWIS frequency is listed in ERSA. AWIS and WATIR service provides real time wind information, the pilot is required to calculate the crosswind component. For example, "wind 360 degrees 25 knots". What is the crosswind component on runway 06? (By the way, AWIS wind is in degrees magnetic). There are a number of ways of determining the crosswind component.
ERSA: In the GEN CON section, find the CONVERSIONS - WIND COMPONENT page. Find the angular difference between the wind and runway directions. In this example (060 - 000) = 60 degrees. Find the column headed 60 then down to the 25 knot wind speed line. Read off the crosswind component (22 knots) at the intersection.ELECTRONIC CALCULATOR: The crosswind component is the sine of the angular difference between the wind and runway directions multiplied by the wind speed. Input: 60 SIN X 25 = 21.65
NAVIGATION COMPUTER: Rotate the azimuth until the wind direction (360) is under the TRUE INDEX. Draw the wind speed down from the grommet to any convenient scale to represent 25 knots. In this example each major grid represents 10 knots. Rotate the azimuth until the runway direction (060) is under the TRUE INDEX. Using the same convenient scale, read Crosswind component (22 knots) and headwind component if required, in this case 12.5 knots.
WINDSOCK: The windsock not only gives a good indication of the direction but can also give a fair idea of the wind speed. Use the Primary windsock - that's the white one. The old style canvas windsocks that were used in the past were just horizontal at 30 knots.
A Primary Wind Indicator in 15+ knots of wind The modern lightweight windsock is horizontal with a windspeed of 15 knots or more. 5° below the horizontal would indicate 10 knots and 30° below the horizontal would indicate 6 knots. A windspeed of 3 knots or more will cause the windsock to rotate about its shaft and indicate the wind direction. Source: Transport Canada Civil Aviation AGA - 5.0 Markers, Markings, Signs and Indicators and FAA Advisory Circular 150/5345-27D - FAA Specification for Wind Cone Assemblies.
How to hold the controls when taxiing in strong wind conditions
Many times whilst taxiing I have noticed pilots either ignoring the wind or having the controls not correctly positioned. The major consideration here is to keep the main wheels firmly planted on the ground and the controls should be positioned at all times to achieve this. The usual thing is to rigidly grasp the control column to stop it flopping around or "snatching" in gusty winds and ignore positioning the control surfaces.
Here is a way to help you remember how to set up the controls for taxiing in ANY wind conditions:"Climb into a Headwind, Descend away from a Tailwind"
So - if the wind is blowing from ahead and the right, the control column should be back and ailerons right. If the wind is blowing from the left rear, the control column should be forward and ailerons left. If the wind is dead abeam from the left, the elevators should be neutral and the ailerons left.
All that is very hard to remember especially with all other distractions associated with preparing for flight. Hence my axiom to help your memory. "Position the controls as you would to Climb into a headwind, and descend away from a tailwind." This is illustrated in the following diagram.
Part 3 of Crosswind Operations in the next newsletter will discuss how to approach and land in a crosswind.
Patrick Watson CP/CFI
Maui from the B737
If you really want to see Hawaii, you have got to fly it! On I recent trip to paradise, I had the time to visit Maui and Maui Aviators for a flight around the islands.
After an early morning 20 minute trip from Honolulu by Aloha Airlines 737, I arrived at Kahului, which is the major airport for the island of Maui. Maui itself was actually formed by sedimentary material thrown up by the two volcanoes that dominate the island. Flying into Kahului on final between East Maui (Haleakala) and West Maui volcanoes gave a preview of the impressive scenery to come. Haleakala is still considered potentially hazardous.Kahului is on the windward side of Maui and, when the trade winds are blowing, light aircraft pilots get plenty of practice with crosswinds. It is an extremely busy, radar and towered airport operating in C class airspace that caters for 737s, 777s, L-1011s MD11s and many large private jets. In addition, the airport supports an impressive helicopter fleet specializing in scenic tours.
Leaving arrivals I walked to the Avis office and secured a four cylinder Chevrolet for US$25 a day. A short drive to the other side of the airport and I arrived at Maui Aviators. Of course the airport is security fenced and the gate was locked. Fortunately the gate is in sight of the hangar and Jonathan came over to let me in.
Kahului, the major airport for the island of Maui Maui Aviators are a Cessna Pilot Centre but having more time on Pipers, I had booked the Archer N6169J. I wasn't due to fly until 9.30am so I had plenty of time to pre-flight the aircraft and make some new acquaintances. I had brought along a Schofields shirt and cap and did a swap with Jon Muralt, the manager, for a couple of Maui Aviator T-shirts. It would appear that GA in Hawaii is under the same pressures that we are in terms of land space and lack of trainee pilots. Jon indicated that in all Hawaii, there are less than 300 GA pilots, so making a living with fixed wing aircraft is very difficult. It is a totally different story for helicopters with figures of US$160 daily start up and then US$60 per hour for pilots.
My guide and instructor, Darren Draholt arrived and we boarded the aircraft and taxied to the run-up area. After run-up, Darren got us taxi clearance and we followed a Dassault Falcon 900 private jet to the holding point. After the Falcon cleared the runway we obtained clearance, lined up and took off, heading east down the coast and over water. The first thing that was very evident was that it would take some time to acclimatise to the communications side of the flight. Between the American accents, the speed of delivery, and the amount of information exchanged, I was happy to let Darren make and take all the calls. The aircraft call sign alone was a mouthful!
Heading down the coast at 1500 feet we over flew sugar cane and pineapple fields and Darren pointed out the 20 million dollar estate of Jim Nabors (Gomer Pyle). Darren also told me that many celebrities such as Oprah Winfrey and Eddie Murphy maintain residences on Maui.
Opening scenes of Jurassic Park were filmed here The coastal strip narrowed quickly as the slopes of Haleakala dominated the landscape. The famous Hana highway was just visible as it wound its way from Kahului to Hana. This road has over 600 sharp curves and 54 one-lane bridges that wind through lush rainforest terrain.
We soon reached Hana airstrip projecting into the ocean and rounded Nanualele Point to pass the town of Hana and Hamoa Beach, 'Alau Island (at Koki Beach), the "sacred" Seven Pools of 'Ohe'o Gulch. At this point whitecaps indicated strong winds and severe turbulence. Up ahead was the gravesite of Charles Lindbergh at Kipahulu, but that would have to keep for another time.
After completing a 180 degree turn we climbed to 2000 feet and followed the coast back to Kaluhui's controlled airspace. Darren obtained clearance and we took a direct line from Opana Point to Nakalele Point. Molokai came into view and we crossed the water to marvel at the famous sea cliffs that drop some 3000 feet into the ocean. During the right months, (Dec - mid May), the waters here are home to humpback whales which can easily be seen from the air. Molokai is small, being only 38 miles long and 10 miles wide. It is largely unspoilt and has only 75,000 visitors a year. It is the only island apart from Ni'Ihau where Hawaiians are in the majority.
Continuing north, Darren pointed out the valley and coast where the opening scenes of Jurassic Park were filmed. Before long the settlement of Kalaupapa came into view. Starting in 1866, Hawaii's victims of Hansen's disease (Leprosy) were dumped on the peninsula and left to die. Today, Hansen's disease is treatable and is one of the least contagious of all communicable diseases. With the arrest of the disease, the remaining small community of resident patients on Kalaupapa chooses to live in the only home they've ever known.
Kaluapapa was our turning point and peering down into the blue waters, the hull and conning tower of a Japanese midget submarine was clearly visible, having run aground after the attack on Pearl Harbour in 1941.
Descending to1500 feet we retraced our route back to Kahului. Helicopter tour traffic was reasonably heavy and radio calls were exchanged identifying each aircrafts position.We were cleared to join on left base and after a small drift courtesy of the cross winds, we touched down and headed back to the parking bay.
If you want to see green vegetation, spectacular scenery and blue waters, I would highly recommend that you look up Jon at Maui Aviators and take a flight. Take one of the instructors/guides with you and you will get the full tour.
Ken Raye
Schoies Member
On Boxing Day 1926 a De Havilland 66 of Imperial Airways flying over the Mediterranean sent out the signal: "The Secretary of State for Air, Sir Samuel Hoare, would like to thank you all and all the other destroyers cooperating today for your valuable assistance, and would like to take this opportunity of wishing you all a happy New Year."
The
Some of the crew on Chopper
Hatchett's history-making flight signal was acknowledged promptly by HMS Vanquisher, one of several destroyers positioned in the Mediteranean watching closely the progress of G-EBMX. The flight was appropriately timed. It was almost the beginning of a New Year, and the birth of the two new eras in air transport and the history of Imperial Airways, later to become BOAC. The signal was sent by a curly-haired 25-year-old radio operator called Edward Hatchett - "Chopper" to his friends.
Opening
It seems that he and his cumbersome Marconi AD6 transmitter were making airline history. It was probably the first time wireless telegraphy had been used in civil aircraft air to ground - or, more precisely, air to sea - communication.
The flight of G-EBMX and its passenger load of VIPs also marked the opening of Imperial Airways Empire routes.
It had left Croydon that Boxing Day bound for Delhi. The journey took several days, but it opened the way for Imperial Airways and later BOAC to build up the largest network of worldwide unduplicated route mileage in the airline business.
The De Havilland 66 was capable of carrying only 14 passengers, at a maximum speed of 90 mph - maybe 120 mph with a strong tailwind.
The destroyers positioned below were not there just as a display of British naval might. Spaced at regular intervals, their job was to pick up the eminent passengers should G-EBMX be forced to ditch! Fortunately, they weren't needed.
Before that first Morse message, Imperial Airways, like most other carriers, was using wireless telephony, or straight speech. This was the responsibility of the captain. The majority of traffic was between Britain and the system was sufficient.
Conducting a pre-flight on G-EMBX But once Imperial Airways decided to inaugurate its Earthshrinking, it had two communication problems to overcome. On a good day, wireless telephony had a range of of only 80 miles. On a bad day it was anybody's guess. Then there was the language barrier.
The answer was Morse code. A range of 200 miles, and no language problem.
Chopper Hatchett had joined Imperial Airways that same year, 1926, and after a spell with Radio Repair and Overhaul at home and abroad, was one of six men selected to become the world's first aircraft radio operators.
They were given a brief training course and licensed.
Chopper's was the first to be issued to an operational radio operator. Licences numbered one, two and three were held by the examining body. He got licence number four.
Mr Hatchett, now 71, lives in Selsdon, near Croydon. He worked for imperial Airways and BOAD for 34 years before retiring in 1958.
It isn't over-dramatic to call him one of the pioneers of civil aviation. He accepts the epithet modestly and recalls with quiet enthusiasm the days when flying was "really flying".
G-EMBX over the Pyramids His main concern, obviously, was with radio, but in the 1920s there was less demarcation on a flight deck. Whatever your particular job, you were probably a Jack of all trades.
As such, people like Chopper were involved not just with one particular aspect of getting an aircraft from A to B, but with the overall industry of flying and the problems that needed ironing out in those early days. Mot the least of these was navigation.
In the 1920s navigation aids were crude and unreliable. You were safest when you could follow landmarks.
Chopper explains: "The majority of navigation was done on sight. In an open cockpit, doing at the most 120 mph, at anything between 50-500 feet, it was possible.
"You had a compass, but more often than not that had a bubble in it." It was often fickle and unreliable, too.
"As one time, for some odd reason, pilots were finding themselves a long way off course - in some cases as much as 60 miles," Chopper recalls.
Degrees
"No one could understand why until one day during a flight I took off my helmet and hung it on a peg near the compass. As I did so the needle swung visibly through several degrees.
"The magnets in the helmet headphones - unknown to us - playing havoc with the compass bearings.
Marconi AD16 aircraft set "Radio helped, of course. Theoretically you should have been in touch with one station or another all the time. Theoretically. In practice you were often very much alone.
"In the main, the radio communications we used were effective, but there were problems. In the desert in particular, sandstorms were a problem. Dust can rise and settle very high up and seriously affect transmissions."
Today, the hardships and the risks of that era when men like Chopper created the airline business seem inconceivable.
In an age when many people regard flying as only marginally more exciting that catching a bus, when passengers are cosseted with good food, drink, music, films and all the amenities of a five-star hotel, consider again that historic flight to Delhi in the dying days of 1926.
One of the navigational lifelines the crew of G-EBMX clung to as they drove over the Syrian desert was, incredibly, an endless furrow in the sand. As long as you stuck to it, you were on course.
It was a furrow that Chopper knew well. During his RAF service before joining Imperial, he and a colleague, backed by a supply team, dug it by dragging a snow plough with motor vehicles across the desert.
From BOAC News, February 2 1973
Submitted by Peter Blackbourn
Today's aircraft communication systems bear little resemblance to the comparatively crude methods used in the pioneer era. In the 50 or so years since the Marconi AD-6, advances in technology have produced systems that would have appeared as incredible to the pilots of the '20s as the conception of an Apollo mooncraft.
Our primary high quality short range radio telephony systems today revolve around VHF radio, by which clear audible speech can be transmitted over a range of 250 nautical miles and is almost 100 per cent reliable.The higher you fly, the greater the range. A range of 260 miles represents a height of about 40,000 feet. Concord, by flying at 60,000 feet, will have a VHF range of about 310 nautical miles.
The range of VHF can be increased by using greater power to transmit signals, but the less the reliability. Theoretically, under certain meteorological conditions, VHF can transmit over 2,000 miles, but at that stage, reliability is low.
Then there is the long range high frequency transmission (HF). In optimum conditions range is unlimited, but reliability is only 75 per cent. That means that roughly only seven out of ten calls can be guaranteed to get through.
Selcal equipment as fitted to VH-HQR BOAC's own radio system, "Speedbird London", provides direct long range communications with our aircraft all over the world. It is a purely company concern, completely divorced from normal ATC.
The high frequency single sideband system uses single sideband techniques and the reliability is increased to about 90 per cent.
The selective call alert system (SELCAL) makes it possible by means of a bell sounded on the flight deck to alert crew that they are wanted on the radio. The system is used on occasions when normal radio watch has been suspended because of heavy interference on HF.
If technology continues to advance at its present rate - and given enough money to turn technical know-how into operational systems - what can we expect in the future?
Greater advances are likely in the field of automatic landings with microwave landing systems; in methods of detecting clear air turbulence and in data communication systems which will enable ground control to monitor the state of nearly all an aircraft's major systems.
From BOAC News, February 2 1973
Submitted by Peter Blackbourn
POSTSCRIPT: "Speedbird LDOC station has pulled the switch - it is with some sadness, and not a bit of disapointment that we report the demise of Speedbird London SSB LDOC (Long Distance Operational Control) station.The big switch was pulled for good on 26 August 2006 at 2300 UTC at the end of the late shift. British Airways, in their wisdom, have given the contract for provision of HF LDOC services to Stockholm Radio and US based company, ARINC who, strangely, seem to have the worldwide monopoly on the ACARS system. presumably market forces had the upper hand and Stockholm put in a cheaper bid that the previous incumbents, Air Radio Ltd, who had operated the service for the last three years since BA's communications branch, (Speedwing Communications) was dissolved. Speedbird London has been on the air, barring breakdowns since first established by BA in 1968. Stockholm Radio have their own website, their HF and Marine frequenciess are listed there, or at least they used to be. First Concorde, now Speedbird London. It's the end of an era."
WHEN IS LIFT GREATEST? Firstly, let's not confuse MASS with WEIGHT. MASS is a dimensionless quantity representing the amount of matter in an object. The standard unit of mass in the International System (SI) is the kilogram (kg). WEIGHT is the force exerted on an object because of its position in a gravitational field. It is equal to the mass of the object multiplied by the magnitude of the gravitational field. A FORCE is an influence that causes a body to accelerate. the SI unit of force is the Newton (N) which is defined as the force that would give a mass of one kilogram an acceleration of one metre per second per second (ms-2). Force is a derived quantity, given by the equation: force = mass × acceleration.
In Antarctica, Earth's gravitational field is greatest Newton's theory of gravitation (which was largely superseded by Einstein's theory of relativity) is still sufficient to explain that a gravitational field is proportional to an object's mass and inversely proportional to the square of the distance from the centre of the object. Therefore, the earth's gravitational field increases the closer we get to the centre of the earth. Gravity or, more precisely, the acceleration due to gravity, 'g', has a value of about 9.78 ms-2 at the equator and about 9.83 ms-2 at the poles (because the earth's radius is greater at the equator). These values are at mean sea level and gravity decreases with altitude or elevation; at 30,000 feet over the equator, 'g' is only 9.75 ms-2. So when is lift greatest? Consider these conditions:
- at a geographic pole ('g' is greatest)
- at low altitude in level flight shortly after take-off ('g' is greatest and the aircraft would have the greatest MASS because its fuel load would still be high)
- in a level, balance turn
FEEDBACK AND CONTRIBUTIONS: Well, that's your Newsletter for this month. With help (in the form of contributions) it might be possible to continue to produce a newsletter every month. Don't forget to check the latest news on the Club's website at www.schofields-flying-club.com.au. Contributions, comments, feedback, and suggestions to latrodectus@schofields-flying-club.com.au.
THOUGHT FOR THE MONTH: Good judgment comes from experience and experience comes from bad judgment. Learn from the mistakes of others. You won't live long enough to make all of them yourself.
Latrodectus
© 2003 Schofields Flying Club Ltd. All Rights Reserved.