Timeline for Why is fuel usage discussed per time, not per distance?
Current License: CC BY-SA 3.0
11 events
| when toggle format | what | by | license | comment | |
|---|---|---|---|---|---|
| Oct 2, 2014 at 3:38 | vote | accept | Volker Siegel | ||
| S Oct 1, 2014 at 13:17 | history | suggested | CommunityBot | CC BY-SA 3.0 |
9 Gallons (= 54 minutes) are in the tank
|
| Oct 1, 2014 at 12:16 | review | Suggested edits | |||
| S Oct 1, 2014 at 13:17 | |||||
| Oct 1, 2014 at 2:20 | comment | added | voretaq7 | @supercat The as-flown distance is 200 miles in all of the examples (the aircraft is traveling along a straight (actually great-circle) 200 mile line from point A to point B) - I've included an image with an example flight fitting the hypothetical profile. The way I've always seen flight planning done wind doesn't change the flight plan distance (which is always measured relative to the Earth's surface), it changes your velocity. You could work it as a distance modification, but the math is much harder so we don't do that :) | |
| Oct 1, 2014 at 2:13 | history | edited | voretaq7 | CC BY-SA 3.0 |
Add an arbitrary 200NM trip plan image.
|
| Oct 1, 2014 at 2:01 | history | edited | voretaq7 | CC BY-SA 3.0 |
added 45 characters in body
|
| Oct 1, 2014 at 0:06 | comment | added | supercat | ...vary depending upon windspeed, though I'm not sure how much. Would that expectation be correct in practice? | |
| Oct 1, 2014 at 0:01 | comment | added | supercat | I would think ground distance traveled would often be a known rather than derived quantity (after all, in many cases the purpose of a flight is to travel between distances a known distance apart), but air distance traveled would be a derived quantity. In your example, the plane travels 10 nautical miles per gallon through the air, but depending upon tailwind/headwind would have to travel between 160 and 266 nautical miles through the air to move 200 miles on the ground. I would expect that the airspeed which would yield the optimal number of ground miles per gallon would... | |
| Sep 30, 2014 at 23:39 | comment | added | Pondlife | You might want to clarify that the legal reserve under (day) VFR is 30 minutes, not 5 gallons :-) | |
| Sep 30, 2014 at 22:48 | comment | added | voretaq7 | In your edits to the question you noted that operating costs are often expressed as dollars-per-hour as well - this is done for similar reasons: Fuel is a dominating factor in operating costs (and for the reasons above we track that per unit time). In addition many maintenance items are dictated on a time(hours)-in-service basis (oil changes, hot section replacement in turbine engines, inspection cycles, etc.), so it's convenient to break down operating costs that way. | |
| Sep 30, 2014 at 22:42 | history | answered | voretaq7 | CC BY-SA 3.0 |