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2018-03-20

MEASUREMENTS  and  STANDARDS

Atlantic Air Combat™ essentially uses the imperials units.  This is not a denyial of the international SI standards, but results from the fact that most background data comes from British or US sources.   It's also the result of bad habits naturally but as these are a common feature among humans, the end product will offer a choice between metric, imperial, and US common units, and even some odd ones if it so happens that these would be better understood by some.   This page is both a reminder of the different values and a helping hand for conversions.  There is no lack of "conversion" websites, but one in particular catched our eye : http://www.convertunits.com  Very friendly, very easy to use

See also :
The Mach Number
AAC Propeller Thrust Calculator
AAC Range Calculator
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Distances 1 nautical mile 1.852 km

On AAC™ pages, distances are usually expressed in nautical miles (nmi).  They may some times show in kilometre (km), yards (yd) or feet (ft) but almost never in statute or land mile (mi)

1 nmi   1.150779 mi     1.852000 km
1 mi   1.609344 km     0.868976 nmi
1 km   0.539957 nmi     0.621371 mi
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Distances Radar Range

In this particular application, radar detection ranges are expressed in yards with any other value being a conversion of the basic data expressed in yards.  Use the tools for precise conversions

±2025 yards   1 nmi   1 nmi   ±2025 yards
1760 yards   1 mile   1 mile   1760 yards
±1094 yards   1 km   1 km   ±1094 yards
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Distances

Measures

1 yard = 3 ft 0.9144 metre

Sometimes, distances are thus expressed in yards, usually because of the background data retrieved.  Also, some dimensions may be expressed in imperial rather than metric values.  When so, such dimensions are shown like this : 10'03" for 10 feet 3 inches.

1 yard (yd)   =   3' or 3 feet =   0.9144 metre
1 foot (ft)   =   12" or 12 inches =   0.3048 metre
1 inch (in)   =   ...   ... ... =   0.0254 metre
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Altitude 1 ft = 0.3048 m|1m 3.2808 feet

Altitude is generally expressed in feet rather than metres, but here are a few quick conversions

3000 feet   =   914 m   1000 m = 3281 feet
9000 feet   =   2743 m   5000 m = 16404 feet
15000 feet   =   4572 m   15000 m = 49213 feet
30000 feet   =   9144 m   20000 m = 65617 feet
45000 feet   =   13716 m   30000 m = 98425 feet
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Speed 1 knot 1.852 km/h

In AAC™ aircraft speed is expressed in knots, meaning 1 nautical mile per hour.  According to preferences, speed may be expressed using other values :

1 knot   1.1507790000000 mph 1.852000 kmh or kph
1 mph   0.8689760000000 knot 1.609344 kmh or kph
1 kmh   0.5399570000000 knot 0.621371 mph    
1 m/min   0.0546806649169 ft/sec   0.055000 ft/sec    
1 m/sec   3.2808398950000 ft/sec   3.281000 ft/sec    
1 m/sec   196.8503937006000 ft/min   196.850000 ft/min    
1 ft/sec   18.2880000000000 m/min   18.288000 m/min    
1 ft/sec   0.3048000000000 m/sec   0.304800 m/sec    
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Weights 1 pound (lb) 0.4536 kg

With most NATO ordnance measured that way, weights are usually expressed in pounds with 0.454kg/lb being referred to.  The actual value of te pound is 0.45359237 kilogrames (rounded to 0.4536) or 2.20462 pounds to the kilogramme (rounded to 2.2046)

1 grain (gr)

0.064799 g or 1/700 lb - unit of measure for bullets weight - not in use in Atlantic Air Combat™.
"gr" may be erroneously used here and there on these pages but it should always be read as grams.

1 ounce (oz) 1 lb = 16 oz 1 oz = 0.625 lb 1 kg = 35.274 oz 1 oz = 28.34952 g
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Weights tonne and ton (short or long)

The word "ton" is a false friend.  Undiscrimininately referring to "10 t" could either mean

1 ton (short) (ton) 907.1847400 kg = 2000.00000 lb 9072 kg 20000 lb
1 ton (long) (imperial) 1016.0469088 kg = 2240.00000 lb 10160 kg 22400 lb
1 tonne (metric) 1000.0000000 kg = 2204.62262 lb 10000 kg 22040 lb
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Weight Standards

In various instances, standard/average weights are referred to.  In particular

crew     200 lb                
airline passenger 225 lb         paratrooper 360 lb
casualty on stretcher 225 lb         commando 300 lb
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Surface

Surface has no practical use in AAC™, but for the sake of mentioning....

  1 = 10.7639104167 ft² rounded value 10.764 ft²
  1 ft² = 0.0929030400 rounded value 0.093
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Volume 1 gallon 4.5461 litres

In AAC™, volumes are generally expressed in imperial gallons (gal) although Aircraft Notes regarding american aircraft may have fuel volumes being referred to in US gallons (US).  As far as the imperial gallon is concerned the main conversion value is 4.55L/gal, but the real ones are:

Volume calculator   1 gallon (US) = 3.785411780 litres   ~ 3.7854 L
  1 gallon (US) = 0.832674188 gallon (IMP) ~ 0.8327 gal
  1 gallon (IMP) = 1.200950420 gallon (US) ~ 1.2010 US
  1 gallon (IMP) = 4.546091880 litres   ~ 4.5461 L
  1 litre = 0.264172051 gallon (US) ~ 0.2642 US
  1 litre = 0.219969157 gallon (IMP) ~ 0.2200 gal
Cubic inches to US gallons     1 inch³ = 0.016387000 litre        
    1 litre = 0.610237400 inch³        
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Fuel Weight

Standard fuel density values in AAC™ are arbitrary and shown herebelow in bold.  Real life values, gathered in US gallons are as follows (fuel weight at 15°C/59°F and 760mm of mercury barometric pressure

click Fuel

US gallon

Imperial gallon

Metric - Litres

click AvGas 6.0000 lb /US 7.2000 lb /gal 0.7200 kg /L
click JA1 (Airline) 6.7400 lb /US 8.0942 lb /gal 0.8076 kg /L
click JP4 (Military 6.5500 lb /US 7.8660 lb /gal 0.7849 kg /L
click JP5 (Military) 6.8200 lb /US 8.1902 lb /gal 0.8172 kg /L
click JPX (AAC) 6.3280 lb /US 7.6000 lb /gal 0.7600 kg /L

For the sake of reference purposes, conversion tools have been assembled, inspired by similar visuals published with http://www.streamline-ops.com/en/info/fuel_weight_conversion_tables/, although the values arrived are different - an error somewhere ?...

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Power Units AAC™ hp or lbf

Engine output is most commonly expressed in hp or in lbf rather than in kW or kN, the universal units of the day.  Accurate and rounded conversion values are shown below :

Piston }   1kW= 1.3404825737 hp or 1000

W =

1.34 hp
Turbines }     1kW= 1.3596216173 ps or 1000

W =

1.36 ps
        1hp= 745.6998715823 W or 1000

hp =

745.70 kw
          1hp= 1.0142777265 ps or 1000

hp =

1024.28 ps
          1ps= 0.9859232574 hp or 1000

ps =

985.92 hp
          1ps= 0.7354987500 kW or 1000

ps =

735.55 kW
Jet }   1kN= 224.8089438700 lbf or 1000

=

224.81 lbf
Rocket }   1 kN= 101.9716212980 kgf or 1000

=

101.97 lbf
        1 kgf= 0.0098066500 kN or 1000

=

9.81 kn
        1 kgf= 2.2046226294 lbf or 1000

=

2204.62 lbf
        1 lbf= 0.0044482216 kN or 1000

=

4.45 kN
        1 lbf= 0.4535923684 kgf or 1000

=

453.59 kgf
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SFC Specific Fuel Consumption lbs/hp/hr or
lbs/lbf/hr

Expressed in mass of fuel per hour, related to the power output, either in "hp" for propeller driving engines or in "lbf" of thrust for jet or rocket engines

Alternatively ... gal/hp/hr or
gal/lbf/hr

If related to fuel volume, then always in imperial gallons (1 gal = 4.55 litres) rather than in other units, and the conversion is made as follows :

AvGas 7.2 lb = 1.000000 gal     1.00 gal/hp/hr = 7.200 lbs/hp/hr
1.0 lb = 0.138888 gal     1.00   lb/hp/hr = 0.139 gal/hp/hr
JPX 7.6 lb = 1.000000 gal     1.00 gal/lbf/hr = 7.600 lbs/lbf/hr
1.0 lb = 0.131579 gal     1.00   lb/lbf/hr = 0.132 gal/lbf/hr
International Units (SI)

As the game AI is likely to use SI units only, it will refer to the following converted values

  1 lb = 0.4536 kg            
and 1 hp = 0.7457 kW   1.00 lb/hp/hr = 0.6083 kg/kW/hr
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and 1 hp = 0.7457 kW   1.00 kg/hp/hr = 1.3410 kg/kW/hr
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and 1 kgf = 0.00980665 kN   1.00 kg/kgf/hr = 101.97 kg/kN/hr
  1 lb = 0.4536 kg            
and 1 lbf = 0.0044482216 kN   1.00 lb/lbf/hr = 101.97 kg/kN/hr
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Ammunition Weight per round

In real life, there is more than the weight of the round to take into account as ammos are set in a feeding system which has a weight of itself.  For example, the standard weight for .50 cal shells seems to be 33lb for 100 rounds.  More information might be found with another source of interest on the matter: http://www.pmulcahy.com/ammunition/autocannon_ammunition.html.  However, in AAC™, it is essentially the weight of rounds that is taken into account to try to figure out ordnance load.  Here are some values - those in dark red are default AAC™ values; others are sourced

   

Ammo

Round

Weight

Belt.100

Belt.500

Belt.1000

Belt.100

 

7.50Χ_55mm

34.g

0.0750.lb

–

29.23.lb

–

10.00.lb

30

7.62Χ–51mm

37.g

0.0816.lb

5.40.lb

–

–

10.00.lb

 

7.70Χ_56mm

33.g

0.0728.lb

10.37.lb

51.85.lb

103.70.lb

10.00.lb

 

7.92Χ–57mm

36.g

0.0794.lb

10.36.lb

51.81.lb

103.62.lb

10.00.lb

50

12.7Χ–99mm

115.g

0.2535.lb

33.00.lb

144.00.lb

288.14.lb

33.00.lb

52

13.2Χ–99mm

118.g

0.2601.lb

–

–

–

34.00.lb

50

12.7Χ107mm

125.g

0.2756.lb

–

–

–

35.00.lb

 

13Χ–64mm

75.g

0.1653.lb

–

–

–

24.00.lb

 

14.5Χ115mm

184.g

0.4056.lb

41.60.lb

–

–

42.00.lb

 

20Χ–72mm

200.g

0.4409.lb

–

–

–

46.00.lb

 

20Χ_82mm

183.g

0.4034.lb

–

–

–

42.00.lb

 

20Χ102mm

230 g

0.5071.lb

70.55 lb

–

705.47 lb

70.00 lb

 

20Χ110mm

260.g

0.5732.lb

76.19 lb

–

–

75.00 lb

  23Χ152mm

467.g

1.0295.lb

139.33.lb

–

–

140.00.lb

 

30Χ113mm

450.g

0.9921.lb

176.37.lb

–

–

175.00.lb

 

30Χ165mm

840.g

1.8519.lb

258.00.lb

–

–

260.00.lb

 

30Χ173mm

890.g

1.9621.lb

270.00.lb

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–

280.00.lb

   

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