DSSCalc Title
DSSCalc Flight Computer for Windows/Pocket PC/Palm OS


Summary of Input and Calculated Values

(as of versions in all platforms shipping November  2005)


Main Menu
Time/Speed/Distance/Fuel
Altitude/Airspeed
Wind/Weather
  Wind Triangle
  Humidity/Clouds
  Sunrise/Sunset
Weight and Balance Menu
  Weight and Balance
  Weight Shift
  Percent Mean Aerodynamic Chord
Performance Menu
  Climb/Descent
  Takeoff Performance
  Fuel Check
  Linear Interpolation
  Turns
Navigation Menu
  Latitude/Longitude
  Time/Distance To Station
  Off Course
Conversions Menu
  Time/Distance Conversions
  Weather Conversions
  Volume/Weight Conversions
Memories


Time/Speed/Distance/Fuel:

Groundspeed Kts -- groundspeed in knots.
Distance -- distance traveled in NM.
Enroute Time -- time enroute in hh:mm:ss format.
Fuel (gallons) -- Total fuel, or fuel required (in gallons), depending on what you are calculating (distance you can go on total fuel, or fuel required to go a distance).
Fuel Flow (gal/hr) -- Fuel flow in gallons per hour, for determining fuel requirements.
Departure Time -- Departure time in hh:mm:ss format.
Arrival time -- Arrival time in hh:mm:ss format.
Fuel (pounds) -- Fuel in pounds, converted to gallons (6 lb./gal for AvGas, as set on the Conversions screen) for computations.
Fuel Flow (lbs/hr) -- Fuel flow in pounds per hour, converted to gallons per hour (6 lb./gal for AvGas, as set on the Conversions screen) for computations.
Fuel (liters) -- Fuel in liters.
Fuel Flow (ltr/hr) -- Fuel flow in liters per hour.
Fuel (kilograms) -- Fuel in kilograms, converted to gallons (6 lb./gal for AvGas, as set on the Conversions screen) for computations.
Fuel Flow (kg/hr) -- Fuel flow in kilograms per hour, converted to gallons per hour (6 lb./gal for AvGas, as set on the Conversions screen) for computations.


Altitude/Airspeed:

Pressure Altitude -- Pressure altitude in feet.
Temp C -- ACTUAL outside air temperature in degrees Celsius.
Indicated Temp C -- INDICATED air temperature in degrees Celsius.
True Airspeed -- True airspeed in knots.
Calibrated Airspeed -- Calibrated airspeed in knots.
Density Altitude -- Density altitude in feet.
Standard Temp C -- Standard temperature for the given pressure altitude in C, calculated only.
Mach Speed -- Mach speed (ratio of TAS to the speed of sound).
Temp Rise C -- Temperature rise from actual OAT to indicated OAT due to probe recovery, air compressibility and friction. Calculated only.
Calibrated Altitude -- Indicated Altitude as read on your altimeter, adjusted for installation errors.
Altimeter Inches Hg -- Barometric altimeter setting in inches of mercury (29.92 is the standard day).
Field Elevation -- Input only, used to compute True Altitude during an approach.
Field Temp C -- Input only, used to compute True Altitude during an approach.
True Altitude -- True Altitude above sea level, adjusted for non-standard temperature and pressure close to a reporting station. Uses the Field Elevation of the reporting station and the altimeter setting reported by the station, as well as the Temperature at your altitude if known and/or the temperature at the field if known. Used mainly during approaches at cold temperatures to compensate for altimeter errors in such conditions.


Wind and Weather Menu:

Select one of the options to select the type of problem you want to solve.


Wind:

Course -- True course in degrees, 0-360.
True Air Speed -- True airspeed in knots.
Wind Direction -- Wind direction in degrees, 0-360. Input or calculated.
Wind Speed -- Wind speed in knots. Input or calculated.
Heading -- Heading flown given the wind, in degrees, 0-360. Input or calculated.
Groundspeed -- Ground speed in knots. Input or calculated.
Crosswind Comp. -- Calculated crosswind component of the wind in knots, negative values are from the left.
Headwind Comp. -- Calculated headwind component of the wind in knots, negative values indicate a tailwind component.


Humidity and Clouds:

Temp C -- ACTUAL outside air temperature in degrees Celsius, as reported from a weather station.
Dewpoint C -- Dewpoint temperature in degrees Celsius, as reported by the weather station used for Temp C.
Rel. Humid. % -- Percentage relative humidity.
Conv. Cloud Base AGL -- Estimated convective cloud base in feet AGL, as derived from temperature/dewpoint spread. Note this calculation is typically accurate to within 2-10%, but only in the case of good air mixing such as under convective conditions.
Cloud Base Temp C -- Estimated temperature of convective clouds at the base of the cloud, subject to the same restrictions given for the Convective Cloud Base estimate of good mixing of air and the assumption of standard lapse rate (which may not be a good assumption in unstable conditions associated with convective activity; when in doubt, find and use the actual lapse rate).


Sunrise and Sunset:

Month 1-12 – The month number 1 to 12 of the date you want to calculate the times for.
Day 1-31 – The day of the month number 1 to 31 of the date you want to calculate the times for.
Year (YYYY) – The four-digit year of the date you want to calculate the times for.
Latitude (+N, -S) – Latitude of location. Use positive values for North, and negative values for South.
Longitude (+W, -E) – Longitude of location. Use positive values for West, and negative values for East.
UTC TimeZone Offset – The number of hours to add or subtract to UTC (Zulu) time to get the local time at the location. NOTE: If you fail to specify this, the calculated times will be in UTC time.
Civil Twilight Begin – The beginning of Civil Twilight.
Official Sunrise – The time of sunrise. NOTE: A value of "99:00:00" means the sun does not rise on that date at that location.
Official Sunset – The time of sunset. NOTE: A value of "99:00:00" means the sun does not set on that date at that location.
Civil Twilight End – The end of Civil Twilight.

Weight and Balance Menu:

Select one of the options to select the type of problem you want to solve.


Weight and Balance:

Weight -- The weight in pounds for the item.
Arm -- The arm in inches for the item.
Moment -- The moment in inch-pounds for the item, given the current reduction factor.
Reduction Factor -- The reduction factor (a constant which is used to divide all moments for ease of display), typically 1 or 1000.
Next Item -- Click on this button to save the current item, perform the weight and balance computation, and prepare for the next item.
Gross Weight -- Calculated gross weight (total weight of all items entered).
CG -- Calculated Center of Gravity.
Total Moment -- Calculated total moment in inch-pounds, given the current reduction factor.
Leading Edge MAC -- Leading edge MAC, usually in inches.
Mean Aero Chord -- Mean Aerodynamic Chord, usually in inches.
Percent MAC -- CG as a percent of MAC, calculated.


Percent Mean Aerodynamic Chord:

Leading Edge MAC -- Leading edge MAC, usually in inches.
Mean Aero Chord -- Mean Aerodynamic Chord, usually in inches.
CG -- CG, usually in inches.
Percent MAC -- CG as a percent of MAC, calculated.

Weight Shift:

Gross Weight -- Total weight of the aircraft and all items in pounds.
Weight Moved -- Weight of the item to be moved, can be input or calculated.
Change In Arm -- Change in arm in inches, input or calculated.
Change In CG -- Change in CG, input or calculated.


Performance Menu:

Select one of the options to select the type of problem you want to solve.


Climb/Descent:

Groundspeed Kts -- Groundspeed in knots (NM/hour), used for both climb and descent problems.
Feet/NM -- Climb/descent rate in feet per NM (from an approach plate).
Feet/Min -- Climb/descent rate in feet per minute (as read on the VSI).
Slope Degrees -- Climb/descent slope angle in degrees (from an approach plate).
Slope % -- Climb/descent slope angle as a percent grade.
Feet to Climb/Desc – Total number of feet you are climbing or descending.
Time to Climb/Desc – Total time (in HH:MM:SS format) you are climbing or descending.
NM Traveled – Total nautical miles traveled over the ground while climbing or descending.


Takeoff Performance:

PLEASE NOTE these are approximations to help you determine the likely effects of up- or downslope, head or tail winds, and changes from Gross Weight on your takeoff performance. In all cases refer to your POH first, and if the manufacturer does not give data for slopes, winds or weight use these calculations as a guideline. Note that experienced bush pilots on sloped fields will often add an extra 20% to 50% over the numbers computed here as a safety factor, and you should too!

POH Takeoff (feet) -- Zero wind, zero slope takeoff distance computed for your current weight/density altitude from the POH, in feet.
% POH Weight -- The percent of the weight used by your POH to determine the POH Takeoff distance you are actually loaded at; for example, if your POH used 2900 pounds as the weight used to determine the POH Takeoff distance and you are actually at 2600 pounds, enter 89.6 here because you are flying at 89.6% of the POH weight.
Headwind -- Headwind component in knots (use the Wind dialog to compute headwind component if necessary). Use negative values for tailwinds.
Liftoff Spd (KTAS) -- Your liftoff speed in Knots TAS; be sure to adjust for density altitude.
Slope Down Degrees -- Down slope in degrees. Use negative numbers for up slopes.
Slope Down % -- Down slope as a percentage. Use negative numbers for up slopes.
Est Takeoff (Feet) -- Estimated takeoff distance in feet given the wind, weight and slope. Remember: your airplane may vary significantly from this value, factor in an additional 25% to 50%!
Breakeven Headwind -- The headwind component at which a headwind exactly balances out an up slope effect, or a tailwind exactly balances a down slope effect, so that mathematically it would make no difference if you take off uphill or downhill. Note that terrain may play a more important role in which choice to make!


Fuel Check:

Start Time – Time the Start Fuel value was valid (hh:mm:ss).
End Time – Time the End Fuel value was valid (hh:mm:ss).
Elapsed Time – Time elapsed between Start and End times.
Start Fuel – Initial fuel value (in any units, but Start/End/Burn Rate must all use the same units).
End Fuel – Final fuel value (in any units, but Start/End/Burn Rate must all use the same units).
Burn Rate/hr – Fuel burn rate per hour (in any units, but Start/End/Burn Rate must all use the same units).
Burn Out – The time at which all fuel will be exhausted.
Minutes Reserve – Number of minutes of reserve fuel you wish to maintain.
Reserve Starts – The time at which you will begin to use your reserve fuel.


Linear Interpolation:

A good example of interpolation is an aircraft power chart. For example, given a 9.5 gph fuel burn (Data Value 1) at 5000 ft (Data Point 1), and a 7.5 gph burn (Data Value 2) at 10000 ft (Data Point 2), what is the burn (Interpolated Value) at 8000 feet (Desired Point)? All data points and values can be times, lat/longs or numbers.
Data Point 1 -- The starting data point for which you have a value.
Data Value 1 -- The value of the item at Data Point 1.
Data Point 2 -- The ending data point for which you have a value.
Data Value 2 -- The value of the item at Data Point 2.
Desired Point -- The data point for which you want to interpolate a value.
Interpolated Value -- The interpolated value at the Desired Data Point, given the values at Data Points 1 and 2.


Turns:

Airspeed Kts -- Airspeed in knots (NM/hour).
Std Rate Turn Bank -- Degrees of bank at the given airspeed for a standard rate (2 minute) turn.
Pivotal Altitude Ft -- The pivotal altitude in feet for the given airspeed, for ground reference maneuvers.
Bank Angle -- Degrees of bank angle you are flying in a turn.
Turn Radius Ft -- The turn radius in feet given the bank angle and airspeed.
Turn Rate /sec -- The turn rate in degrees per second given the bank angle and airspeed.


Navigation Menu:

Select one of the options to select the type of problem you want to solve.


Latitude/Longitude:

NOTE: You should enter Lat/Long values as if they were Time values, using colon : to separate the degrees, minutes and seconds. You can use decimal numbers (151.2345), degrees:decimal minutes (151:32.554), or degree: minutes:decimal seconds (151:32:33.45). On the display, the colons will be converted to degree and minute markers. Note that lat/long and time values are equivalent, and are stored identically, so it is possible to have a time value on the display that still functions as a lat/long entry.
You may enter an ending lat/long and initial True Course and distance will be calculated, or you can enter a distance and radial (True Course) from the starting point and the ending lat/long will be computed.
Latitude 1 -- Latitude of starting point. Use positive values for North, and negative values for South.
Longitude 1 -- Longitude of starting point. Use positive values for West, and negative values for East.
Latitude 2 -- Latitude of ending point. Use positive values for North, and negative values for South.
Longitude 2 -- Longitude of starting point. Use positive values for West, and negative values for East.
Great Circle Distance -- Great Circle distance from the starting to the ending point.
GC Init Tr Crs/Radial -- Initial True Course from the starting point. Note that the course typically changes over a Great Circle route, so this is only the initial course from the starting point.
Rhumb Line Distance -- Rhumb line distance from the starting point to the ending point.
RL True Crs/Radial -- Rhumb Line True Course from the starting point. Note that rhumb lines have a constant course over the entire distance.


Time/Distance To Station:

This screen solves the time/distance to station problem, in which you turn off course (10 degrees, for example), then time how long it takes to reach the radial that is the same amount off as you turned off course (in this example, reaching the 150 radial when you started on the 140 radial and turned 10 degrees off course).

True Airspeed Kts – True Airspeed (TAS) in knots.
Time Bearing Change – The amount of time (in HH:MM:SS format) that it took to reach the target bearing.
Degrees Bearing Change – The number of degrees of bearing change traveled in the time specified.
Time To Station – Time to the station in HH:MM:SS format.
NM Distance to Station – Distance to station in nautical miles.


Off Course:

This screen solves the "off course" problem, in which you have determined you are off course by a certain distance and need to know how many degrees to turn to arrive at the destination. You can use SM or NM on this screen as long as all three Miles values use the same kind.

Miles Flown – Miles you have flown so far.
Miles Off Course – Miles you are off course (distance from where you are to the original course line).
Miles To Fly – Miles remaining to be flown to the destination.
Degrees Correction Angle – The correction angle to turn back towards the course to arrive at the destination location.


Conversions Menu:

Select one of the options to select the type of problem you want to solve.


Time/Distance Conversions:

Nautical Miles, Statute Miles, Kilometers, Feet, Meters, Inches -- enter any of these and the others will be computed.
Time (HH:MM:SS) -- Time as a time format hh:mm:ss.
Time (Decimal Hrs) -- Time as a decimal format (i.e. 2.3 hours)
Time (Decimal Mins) -- Time in minutes as a decimal format (i.e. 14.7 minutes)


Weather Conversions:

Degrees Fahrenheit/Celsius -- enter either of these and the other will be computed. Note in the Calculator mode you can use the "F > C" and "C > F" buttons to convert between temperature types as well.
Inches Hg, Millibars -- enter either of these and the other will be computed.


Volume/Weight Conversions:

Gallons, Liters, Imperial Gallons -- enter any of these and the others will be computed.
Lbs Fuel -- Pounds of fuel computed using the fuel lbs/gal input to gallons, then converted to pounds.
Kg Fuel -- Kilograms of fuel, computed using the Avgas lbs/gal input to gallons, then converted to kilograms.
Fuel Lbs/Gal -- Sets the pounds per gallon of fuel used throughout the program, traditionally 6 lb/gal for AvGas (100LL) in most POHs (but 5.8 is closer to reality).
Pounds, Kilograms -- enter either of these and the other will be computed.


Memories:

Memories 0 through 9 are represented here. You can store to the memories by clicking on the appropriate menu button Memory 0 through 9. This screen gives you a convenient way to see all of the items currently stored.