ppl_03_e2

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Customer: Oleg Ostapenko E-mail: ostapenko2002@yahoo.com

Customer: Oleg Ostapenko E-mail: ostapenko2002@yahoo.com

CHAPTER 11: THE NAVIGATION COMPUTER

Let us assume that, following pre-flight mass & balance calculations, you discover that the weight of fuel in the aircraft’s tanks may amount to 150 lb without overloading the aircraft or putting the aircraft’s centre of gravity outside limits. You wish to know, therefore, what volume of fuel 150 lb represents in US gallons and litres, so that you can carry the maximum amount of fuel permitted by the mass & balance calculations.

You can use your navigation computer to carry out this calculation. You just have to adapt slightly the method that you have just learnt for calculating weight from volume.

This time, you place 15 on the inner scale of the computer, representing 150 lb of AVGAS, against 72 on the lb Sp.G. scale, using the cursor to assist you. (See Figure 11.18.)

Figure 11.18 Calculating what volume in US gallons or litres may be carried for an allowable fuel load of 150 lb.

Now rotate the cursor to line up with the US GAL index and read off, on the inner scale, the equivalent volume of fuel: 25 US gallons. (Your mental calculation based on AVGAS weighing about 6 lb per US gallon confirms the magnitude of the value represented by the figures 25.)

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Customer: Oleg Ostapenko E-mail: ostapenko2002@yahoo.com

CHAPTER 11: THE NAVIGATION COMPUTER

Finally rotate the cursor to line up with the km-m-ltr index and read off 95 litres. (Your mental calculation based on AVGAS weighing about 1.6 lb per litre confirms the magnitude of the value represented by the figures 95.)

You may use the CD-ROM to practise further volume to weight and weight to volume conversions.

CONVERSIONS OF UNITS OF VOLUME.

We will finish this introductory chapter on the use of the navigation computer, by carrying out simple conversions of units of volume. As we have just been carrying out fuel calculations, we will convert between US gallons, Imperial gallons and litres.

These calculations may well be necessary to a pilot flying in Britain or Europe, if he is operating an aircraft built in the United States of America. US aircraft inevitably have fuel gauges graduated in US gallons, whereas, in Britain and Europe, fuel may be uploaded in litres, Imperial gallons or US gallons.

We will, therefore, convert the total fuel quantity required for the Oxford Kidlington-

Ledbury - Wellesbourne Mountford flight, from US gallons to litres. Having decided to carry 35 US gallons of fuel, you see from the aircraft’s fuel gauges that there are already 20 US gallons in the tanks. Consequently you need to take on a further 15

Figure 11.19 Converting 15 US gallons to litres.

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Customer: Oleg Ostapenko E-mail: ostapenko2002@yahoo.com

CHAPTER 11: THE NAVIGATION COMPUTER

US gallons. The fuel bowser from which you plan to refuel delivers fuel in litres so, using your navigation computer, you calculate how many litres are the equivalent of 15 US gallons.

The operation is simple. Locate the yellow indicator annotated US GAL on the outer rim of the circular slide rule face of the navigation computer, and position the centre line of the cursor over the point of the US GAL indicator, as illustrated in Figure 11.19.

You now adjust the moveable inner scale so that 15, on the inner blue scale, representing 15 US gallons, is positioned under the centre line of the cursor. Now simply move your cursor to line up with the pointer of the red flag marked km-m-ltr, as illustrated in Figure 11.20.

Figure 11.20 15 US gallons is equal to about 57 litres.

The symbols km-m-ltr stands for kilometres-metres-litres; this flag is used for all conversion operations involving those three units. At present, of course, you are interested in litres.

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CHAPTER 11: THE NAVIGATION COMPUTER

Underneath the cursor’s centre line, read off the value 573. Knowing that there are about 4 litres in a US gallon, a quick mental calculation confirms that 573 is to be read as 57.3 litres. This, then, is the amount of fuel that you need to upload from the bowser.

All conversion calculations between units are carried out in this way. The CD-ROM will teach you how to make all types of conversions, and will give you practice in as many test questions as you wish.

CONCLUSION.

The aim of this chapter has been to teach you the use of the Dalton-type dead reckoning computer in carrying out the principal calculations that concern the pilotnavigator when preparing a cross country flight.

There are many other types of calculation which may be made on the navigation computer that we do not mention here.

However, all functions of the navigation computer are taught on the navigation computer training CD-ROM which accompanies this book. Please study the CDROM carefully before taking your navigation examination.

Bear in mind, too, that despite this being the age of the digital computer, the traditional Dalton-type analogue computer will give you all the accuracy you require for the navigation calculations you will perform during flight planning. The Dalton-type navigation computer does not, of course, need any kind of power source other than yourself, so it will rarely, if ever, let you down.

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Customer: Oleg Ostapenko E-mail: ostapenko2002@yahoo.com

Customer: Oleg Ostapenko E-mail: ostapenko2002@yahoo.com

CHAPTER 11: THE NAVIGATION COMPUTER QUESTIONS

Representative PPL - type questions to test your theoretical knowledge of The Navigation Computer.

1.If magnetic variation in a certain part of the world is given as so many degrees East, then:

a.True North is East of Magnetic North

b.Compass North is West of Magnetic North

c.True North is West of Magnetic North

d.Magnetic North is West of Compass North

2.Select the correct option to fill out the blanks of the table below:

a.4°E, 277°

b.4°W, 271°

c.4°W, 277°

d.4°E, 271°

3.Using the wind face of your flight computer, complete the table shown below:

c.015 90

d.015 97

4.Using the wind face of your flight computer, complete the table shown below:

c.057 190

d.055 188

5.Using the wind face of your flight computer, complete the table shown below:

a.129º 90 knots

b.123º 120 knots

c.102º 90 knots

d.124º 92 knots

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CHAPTER 11: THE NAVIGATION COMPUTER QUESTIONS

6.Using the wind face of your flight computer, complete the table shown below:

7.Using the wind face of your flight computer, complete the table shown below:

a.285º 100 knots

b.275º 100 knots

c.270º 95 knots

d.279º 105 knots

8.Using the circular slide rule on your flight computer for distance, speed, time and conversion calculations, complete the table shown below:

9.Using the circular slide rule on your flight computer for true airspeed (TAS) and altitude conversions complete the table shown below. Assume that indicated airspeed (IAS) is the same as rectified airspeed.

a.115

b.150

c.193

d.120

10.You are planning a cross-country flight on which your desired track is 340º True. Your planned TAS is 89 knots and the forecast wind speed is 130/14. What true heading must be flown to maintain this track, and what will be your groundspeed?

a.335º True 101 knots

b.345º True 76 knots

c.335º True 76 knots

d.345º True 101 knots

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Customer: Oleg Ostapenko E-mail: ostapenko2002@yahoo.com

CHAPTER 11: THE NAVIGATION COMPUTER QUESTIONS

11.Using the circular slide rule on your flight computer for true airspeed (TAS) and altitude conversions complete the table shown below. Assume that indicated airspeed (IAS) is the same as rectified airspeed.

12.Using the circular slide rule on your flight computer for distance, speed, time and conversion calculations, complete the table shown below:

13.Using the circular slide rule on your flight computer for distance, speed, time and conversion calculations, complete the table shown below:

14.Using the circular slide rule on your flight computer for distance, speed, time and conversion calculations, complete the table shown below:

FOR THE REMAINING QUESTIONS, ASSUME THAT AVGAS HAS A SPECIFIC

GRAVITY OF 0.72.

15.What is the weight in lb of your fuel load if your aircraft’s tanks hold 25 US gallons?

a.149 lb

b.68 lb

c.25 lb

d.180 lb

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Customer: Oleg Ostapenko E-mail: ostapenko2002@yahoo.com

CHAPTER 11: THE NAVIGATION COMPUTER QUESTIONS

16.What quantity of fuel can you carry in US gallons if you calculate that your aircraft may carry 230 lb of fuel?

a.69 gallons

b.41.5 gallons

c.32 gallons

d.38 gallons

17.What is the weight in lb of your fuel load if your aircraft’s tanks hold 75 litres?

a.54 lb

b.68 lb

c.25 lb

d.118 lb

18.What quantity of fuel can you carry in litres if you calculate that your aircraft may carry 150 lb fuel?

a.69 litres

b.21 litres

c.95 litres

d.63 litres

The answers to these questions can be found at the end of this book.

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CHAPTER 12

FLIGHT PLANNING

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CHAPTER 12: FLIGHT PLANNING

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