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Flights News On The Last Scheduled DC-3 service On Planet Earth

The DC-3 is the oldest aircraft in the market and we have a story on it in this October article.

To  get a ride on the last scheduled DC-3 airline service on planet Earth, you have to travel to Yellowknife Airport, located at 62 degrees ,26 minutes,32 seconds North by 114 degrees,23 minutes,51 seconds West. That will put you just 318 miles south of the Arctic Circle.

It is operated by locally-based Buffalo Airways which also operates other scheduled passenger, charter passenger, charter cargo, fire-fighting and fuel services. Its main is at Yellowknife Airport with two other bases at HAY River Airport and Red Deer Regional Airport in the Canadian Northwest Territories.

Yellowknife (the name comes from the hunting knives forged from the naturally occurring copper used by the local Dene people) ,is the only city and the  capital of the Northwest Territories and has a population of approximately 19000. The second largest town in the Northwest Territories in Hay River, with a population of approximately 3600. The total population of the Northwest Territories is about 45000 in an area that is double the size of the US state of Texas.

The challenge in this land is getting around the Canadian north, which can often be a hit-and-miss affair, especially in winter. The emptiness of this vast, featureless land, coupled with unpredictable and often ferocious weather conditions that have swallowed pilots, passengers and their aircraft whole ,never o be  seen or heard from again, is always a worrisome factor.

One pilot disappeared on a routine winter flight in 1964.His remains and those of his passengers were only discovered in 2003, almost 40 years later.

Travelling at 170 miles per hour, Buffalo Airways DC-3s can haul 7000 pounds of freight or 28 passengers to destinations throughout the Canadian North. About one half of its passengers are repeat customers.

Buffalo Airways has been operating its legendary DC-3 aircraft with their trademark green livery since 1970. Most of Buffalo Airways’ warbird airliners date back to WWII and include 13 DC-3s, a couple of DC-4s, and Curtiss C-46s, two Lockheed Electras (the company’s only two turboprops) and two Canadair CL-125 Fire Bombers.

Today it is the only airline in the world to fly, a seven day a week, scheduled DC-3 services between Yellowknife and the Hay River Airports. The flight takes approximately 45 minutes.

According to Mickey McBryan, the current general manager and son of the legendary Buffalo Joe McBryan, the founder, and current president of Buffalo Airways, the name came from one of Joes first flying jobs, counting buffalo. Mickey says his father made the first flight to Hay River around 1970, and has since made the flight over 7500 times.

Buffalo Airways, has been the subject of the popular Canadian reality television series,Ice Pilots NWT-a 13-episode real-life documentary series about an unorthodox airline in the Canadian North.

Yellowknife –based Buffalo Airways flies WWII-era propeller ‘planes-big old aircraft built by “Rosie the Riveter” that have remained virtually unchanged over the years. Rookie pilots defy bone-chilling temperatures to fly cargo and passengers through blizzards, breakdowns, and transatlantic journeys. It is an impossible job in a merciless place.

Every pilot starts at the bottom-as a “rampie” .they work the ramp in minus 10 degrees Celsius, and if they have what it takes they will eventually sit in the right seat of a DC-3, and  sometime in the future they will move to the left seat.

The climate demands courage, character and mental toughness. The pilots of Buffalo Airways have those traits, if they don’t, they leave. McBryan says they have about a 95% pilot turnover rate.

The real meat and potatoes of the Buffalo Airways business

are the freight. Three DC-3s are reserved for passenger service, and the others for freight. Depending on the load, they may use a DC-3 or DC-4.

Grocery stores and other merchants depend on Buffalo Airways to get supplies to them all year long,and winter is the biggest challenge.

The area does not have permanent roads, and the only way people can be resupplied in winter is by Buffalo Airways. At some point during the winter, Yellowknife is literally cut off from civilization. The pilots of Buffalo Airways’ job are to bring food, fuel, medicines and freight from civilization to remote, isolated settlements around the Arctic Circle.

They have hauled everything from dogsleds and dogs to the Stanley Cup, ice hockey’s top prize. The challenge has been and always will be the weather. In winter, temperatures can go to -40 deg.C and winds can gust to 40 mph, and there is a lot of snow.

Each spring, the mile-long ice bridge over the Mackenzie River breaks up and flows out to the Beauford Sea, severing the only “road” leading from southern Canada to Yellowknife. For more than four weeks, and another month each autumn, the city of Yellowknife remains cut off from the rest of the world. The only access to the city and its outlining settlements during those periods is by air and Buffalo Airways.

The pilots and passengers of Buffalo Airways may not think much about the fact that they are travelling in a virtual time machine that its designers had no idea it would out last all of them, and it is still going 75 years later.

Anthony Juma is the Editor  and Senior Aviation Director at Wings Over Africa Aviation. 
This is an Air Charter Company that specializes on Providing  Different Types of Fleet for Both Cargo & Passengers In Kenya|Uganda|Africa|East Africa|Tanzania|Burundi |Rwanda for Charter & Scheduled Flights The website has guided thousands of travelers to achieve their dream holiday. For more information and guidance, visit the site at http:// www.wingsoverafrica-aviation.com/index.php/our-fleet.html

 

Understanding & Using Solar DC-AC Inverters ? Part 5

Understanding & Using Solar DC-AC Inverters – Part 5

Inverters & safety

 

Finally, there are a couple of important safety aspects to bear in mind whenever

You’re using a DC-AC inverter. Many people assume that because an inverter is operating from a nominal 12V battery and it can’t deliver as much output as a normal mains power outlet, its relatively safe. Nothing could be further from the truth.

 

Even a low power inverter rated at a mere 60 watts has an output which is

potentially fatal, if you should end up connected across it. Such an inverter can

typically deliver up to about 360mA at 230V, which is over TEN TIMES the

current level needed to stop your heart and cause fatal fibrillation!

Needless to say higher power inverters are even more dangerous.

 

 

There.s also another kind of safety risk associated with inverters, which arises

from the fact that in many inverters, there.s a direct electrical path between the

mains-voltage output circuit and the low voltage input circuitry (including the

battery leads). This path is usually via the auto turn-on sensing, and possibly

also the voltage or current sensing used for output regulation.

 

When the inverter is being used to power a single tool or appliance, this internal

current path normally doesn.t pose any safety risk because the complete batteryinverter-

 

appliance system .floats. above earth. However if the tool or appliance

is faulty and develops a short circuit or severe leakage between its mains wiring

and its external metal case or frame (which would normally be earthed, when

it.s plugged into a mains power outlet), there.s a risk that the battery connections can become dangerously .live..

 

How can this happen? Think about it: if the leakage path to the appliance.s

frame happens to be from the side of its mains wiring connected to the .active.

side of the inverter.s output, and the frame of the appliance becomes connected

to earth, this will immediately raise the .neutral. side of the inverter.s output to

the full output voltage above earth .

 

and with it, the low voltage side of the inverter.s circuitry and the battery terminals as well. So if an unsuspecting person who also happens to be earthed should touch one of those safe-looking 12V battery terminals, they can receive a potentially fatal shock.

 

It.s for this reason that inverter manufacturers and suppliers generally advise

strongly against connecting an inverter into the permanent wiring of a house,

office or factory . especially in a way where the appliances connected to its

output tend to become automatically connected to mains earth, and/or linked

back to mains neutral (which is ultimately earthed, with the MEN system).

 

If you want to run a number of appliances from a single high-power inverter,

and have the convenience of permanent wiring and mains-type power outlets,

the safest approach is to have a wiring system and outlets that are kept totally

separate from any wiring that is connected to the AC mains and mains earth. The

outlets driven from the inverter output are also best left unearthed, and clearly

marked as .

 

INVERTER POWER: FLOATING..

 

This totally separate, floating system not only reduces the risk of accidental

shocks due to faulty appliances, but also helps to remind users so they don.t

accidentally plug inappropriate appliances into the inverter outlets.

In any case, always think twice before touching the terminals of a battery that

you know is being used to power tools or appliances via a DC-AC inverter.

 

Remember that there.s always a risk those battery terminals could deliver you a

much greater shock than you.d ever get from 13.8 volts, if one of those tools or

appliances should develop a fault.

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Understanding & Using Solar DC-AC Inverters – Part 4

Understanding & Using Solar DC-AC Inverters – Part 4

Sinewave inverters

 

As explained earlier, most DC-AC inverters deliver a .modified sinewave. output

voltage, because they convert the incoming DC into AC by using MOSFET

transistors as electronic switches.

 

This gives very high conversion efficiency, but the .alternating pulses. output waveform is also relatively rich in harmonics.

 

Some appliances are less than happy with such a supply waveform, however .

examples include light dimmers, variable speed drills, sewing machine speed

controls and some laser printers. Because of this, inverter manufacturers do

make a small number of models which are designed to deliver a pure sinewave

output.

 

Generally speaking these inverters use rather more complex circuitry than

the .modified sinewave. type, because it.s hard to produce a pure sinewave

output while still converting the energy into AC efficiently. As a result pure

sinewave inverters tend to be significantly more expensive, for the same output

power rating.

 

The most common type of pure sinewave inverter operates by first converting the

low voltage DC into high voltage DC, using a high frequency DC-DC converter. It

then uses a high frequency PWM system to convert the high voltage DC into

.chopped.

 

AC, which is passed through an L-C lowpass filter to produce the final

clean 50Hz sinewave output. This is like a high-voltage version of the single-bit

digital to analog conversion process used in many CD players.

Don.t reverse polarity!

 

A lot of electronic equipment designed to be operated from a battery is fitted

with an internal diode in series with one battery lead, to protect the equipment

from damage if the connections to the battery are accidentally reversed.

 

But this type of reverse polarity is generally not fitted to DC-AC inverters, because of the heavy current drain involved. The additional voltage drop introduced by a diode

would degrade the inverter.s regulation too much, quite apart from wasting power and hence reducing the overall efficiency.

 

If reverse polarity protection is provided, this is usually in the form of a

protective fuse or circuit breaker in series with the battery leads, plus a reversedpolarity power diode connected across the inverter.s DC input (after the fuse: This means that when the battery leads are connected with the correct

polarity, the diode is reverse biased and remains dormant. But if the battery

connections are accidentally reversed, the diode is forward biased and suddenly

conducts . blowing the fuse and hopefully protecting the inverter itself.

 

This system generally does provide protection against reversed-polarity damage

to most of the inverter circuitry, without degrading its efficiency or output

regulation. However the price you pay is that an accidental reversal of the

battery connections still blows a fairly expensive high-current fuse, and

sometimes also destroys the protective shunt diode as well.

 

Probably for this reason, some lower priced inverters don’t incorporate any

specific protection against accidental reversal of the battery leads. So with these

inverters, you have to be especially careful to connect the battery leads correctly.

Even with inverters which are provided with protection, it’s still a very good idea

to double-check the connections before clipping on the second battery lead.

Remember that a mistake will almost certainly mean a blown fuse at least, and

possibly a long delay until you can replace it!

 

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Understanding & Using Solar DC-AC Inverters – Part 3

Understanding & Using Solar DC-AC Inverters – Part 3

Capacitive loading

 

Actually there.s a different kind of problem with many kinds of fluorescent light

assembly: not so much inductive loading, but capacitive loading.

Although a standard fluoro light assembly represents a very inductive load due

to its ballast choke, most are designed to be operated from standard AC mains

power. As a result they.re often provided with a shunt capacitor designed to

correct their power factor when they.re connected to the mains and driven with a

50Hz sinewave.

 

The problem is that when these lights are connected to a DC-AC inverter with its

.modified sinewave. output, rich in harmonics, the shunt capacitor doesn.t just

.correct. the power factor, but drastically over corrects . because its impedance

is much lower at the harmonic frequencies. As a result, the fluoro assembly

draws a heavily capacitive load current, and can easily overload the inverter.

In cases where fluorescent lights must be run from an inverter, and the lights are

not going to be run from the mains again, usually the best solution is to either

remove their power factor correction capacitors altogether or replace them with a

much smaller value.

 

Auto starting

 

Many inverters are provided with a power switch, and must be turned on before

they supply AC power. However some models are provided with .auto turn-on., so

they stop working when the AC load is removed, but turn on again automatically

when a load is connected. This allows the power switch of an appliance or tool to

be used to control the inverter.s operation as well, conserving battery energy

while still allowing the appliance to be operated in exactly the same way as

when it.s connected to the mains.

 

In most cases this auto turn-on system uses a sensing circuit connected into the

inverter.s output loop, and designed to detect when the appliance switch is

closed . to complete the high voltage circuit. This allows a small DC sensing

current to flow, and this current is used to turn on the inverter.s MOSFET drive

circuitry.

 

When no DC flows in the output loop, the drive circuitry is disabled and no

pulses are fed to the gates of the MOSFETs. As a result they don.t conduct, and

the inverter doesn.t operate. Only a very small .standby. current is drawn from

the battery.

 

Note, however, that because this kind of auto turn-on circuit uses a small direct

current to sense when the appliance has been turned on, it relies on the

appliance providing a DC path when its mains switch is closed. If the appliance

doesn.t provide such a path, the auto turn-on circuit won.t work.

So with some appliances, the inverter may still need to be turned on and off

manually when it.s needed.

 

Frequency stability

 

Although most appliances and tools designed for mains power can tolerate a

small variation in supply frequency, they can malfunction, overheat or even be

damaged if the frequency changes significantly. Examples are electromechanical

timers, clocks with small synchronous motors, turntables in older .vinyl. record

players and many reel-to-reel tape recorders.

To avoid such problems, most DC-AC inverters include circuitry to ensure that the

inverter.s output frequency stays very close to the nominal mains frequency:

50Hz in the case of Australia, New Zealand and most European countries, or

60Hz in North America.

 

In some inverters this is achieved by using a quartz crystal oscillator and divider

system to generate the master timing for the MOSFET drive pulses. Others simply

use a fairly stable oscillator with R-C timing, fed via a voltage regulator to

ensure that the oscillator frequency doesn.t change even if the battery voltage

varies quite widely.

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