3 ms·
It saves fuel for the downwind leg of the trip. However, it's worth noting that if the outward (downwind) and return (upwind) legs are affected by the same win
by jfk13 8y ago
It saves fuel for the downwind leg of the trip.
However, it's worth noting that if the outward (downwind) and return (upwind) legs are affected by the same wind, the outward savings are more than offset by the extra fuel needed for the return. Suppose the journey in your example is 200 miles. With no wind, that's an hour each way, so 2 hours total cruising time.
With the 100mph wind, the outward journey only takes 40 minutes (200 miles at 300mph), but the return takes 2 hours (200 miles at 100mph) for a total cruising time of 2:40, and a significantly greater total fuel burn.
(In practice, airlines may route the two legs quite differently to optimize better, taking advantage of the tailwind in one direction while avoiding it as much as possible when going the other way.)
- cyberferret 8y agoI distinctly remember my CFI in flying school brow beating it into us rookie pilots that "what you lose in a headwind, you never regain in the tailwind on the way back", and explaining it to us long handed on the blackboard. Seems illogical, but the math stacked up as in your illustration above.
- TomVDB 8y agoMy standard way to think about stuff like that is to extrapolate to infinity: even if your tail wind were infinite and you’d arrive in 0 time, your way back would have infinite headwind and you’d never make it back. Conclusion: increased wind increases the round trip time.
- photojosh 8y agoI know this principle quite well from... riding a bike. Wind resistance dominates as soon as you get above a casual riding speed.