BrainTeaser

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Whirlydog

Senior Member
Joined
Nov 3, 2003
Messages
186
Location
Estancia New Mexico
Aircraft
dream
Total Flight Time
none
My company flew me overseas recently and looking at my flight times on the ticket I noticed something that seems a little strange at the time. Flying from the state to Europe the particular flight is 12hrs long, while the trip back is only 10. Thinking about it for a moment, I wonder how can this be? Weather patterns go from west to east, so a plane would tend to have a tailwind flying east and a headwind flying west. That would make you think it should be the opposite ie. 10hrs to fly east and 12hrs to fly west.

I figure out the answer. I thought this might be a neat brain teaser and wonder how long it would take before someone responded with the correct answer. Chuck B and other airline pilots or contintal flying pilots please don't respond. Let see what the everyday guy thinks.

Shawn
 
Earth's rotation west to east. The earth spins under the plane faster in one direction (east to west) than it does in the other direction (west to east).

Nasa launches missiles west to east because the earth's spin aids in gaining escape velocity.

Some of the trade winds go east to west. The weather dynamic of a low or high pressure system has the winds going one direction from a ground stand point.
I was taught in the army that if I had my back to the wind and I held out my left hand , the left hand would point to a low pressure area. Look at a satellite picture of the swirling cloud patterns they are in bands.
Columbus used them.
 
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The Air route taken. One over the pole while the other over the ocean. Longer route over the ocean.
 
Worm hole,

Time Warp,

Subspace Conduit,

The plane flew slower coming back.
 
Ray had it right. it is due to the rotation of the earth. imagine lifting off the face of the earth and holding still, after some period of time you came straight down. you would be further west than when you started. Do it on a globe, lift your finger off the globe, turn the globe west to east with your other hand then put you finger back down. See what I mean.

Yes you can have trade winds that travel east to west, but if you watch the weather every day we look to the west to see what is headed our direction. Thus is the reason I say the prevalent winds you might encounter are west to east.

Ray you had it right in your first post, before you edited it and made it more clear. I did not say so then, becuase I wanted to see a few other answers first.


You all have a good day ya hear.

Shawn
 
Whirlydog said:
Ray had it right. it is due to the rotation of the earth. imagine lifting off the face of the earth and holding still, after some period of time you came straight down. you would be further west than when you started. Do it on a globe, lift your finger off the globe, turn the globe west to east with your other hand then put you finger back down. See what I mean.

Yes you can have trade winds that travel east to west, but if you watch the weather every day we look to the west to see what is headed our direction. Thus is the reason I say the prevalent winds you might encounter are west to east.

Ray you had it right in your first post, before you edited it and made it more clear. I did not say so then, becuase I wanted to see a few other answers first.


You all have a good day ya hear.

Shawn
Click to expand...

Departure time and arrival time are local times for each city. They are not the flying time of the aircraft.

One of the best examples is with the SR-71. There is many examples where the SR-71 (using local times) they landed before they took-off. Using your logic they flew faster than the speed of light. It is fast but not that fast.

Leon
(kc0iv)
 
WhirleyDog- I have to disagree with your earth rotational speed causing any change in travel time according to your theory. If this were there the case-the rotational speed of the earth at our latitude is at or faster than the typical cruising speed of a commercial airliner. When crossing the Atlantic to the east- according to your theory - you would never get there as the earths surface is moving faster! Now- if we are talking putting a satellite into orbit, then most certainly an eastward launch gets to start out with this free speed that the latitude of the launch site gives it. Stan
 
While were on the subject of the earth rotation....now if you were to fire a projectile at a target...the earths rotation is a big deal.

North of the equator...you must aim to the left of the target when firing any direction.

Simple reason being....say you are north of the equator..and shooting towards the south. Your target is moving faster than you since its closer to the equator and it has a higher rotational velocity. You have to aim left to hit it.

Likewise shooting at a target to the north of you...your target is going slower than you and again you have to aim left of it.

This is still true even if your target is due east of you. You have to aim to the left as the target will drift to the north due to the earths rotation...and if your target is west of you...you still must aim left of it as your target will drift to the south.


Everything is just the opposite south of the equator.

The amounts of correction of course depend on the hangtime of the projectile....distance of latitude being crossed....and some other variables I do not know. I know reading one instance where a projectile traveling 25 miles had to have a correction of aim of around 400 feet. Pretty substantial when considering the size of the blast zone....unless its a nuclear weapon.:boom:
 
I'm going to have to amend my earlier post.
Sir Isaac Newton disagrees with my first statement.

Objects in motion tend to stay that way unless acted upon.
The gravity is constant. The earth's equatorial speed is constant. Do the math.
And we are matching that same speed through space.

It would have to be wind currents. Else balloons would never travel east. The earth would simply move underneath and the sun would never be out of sight of the balloon.

I looked at flight times between Atlanta and Dallas. It's the same both ways.
2 hours and 31 minutes.
 
Wow a few more amswers than expected. But I will stand by my simple answer.

1. The flight path to and from are the same. Air speed is probably a close match also both directions

2. The actual flight times are based on 1000s of flights with head/tail winds averaged into the account.

3. The Prevelent winds these planes face are winds are west to east. Yes there can be weather patterns that will be opposite in nature. I will use this as proof: Every year in albuquerque we have a Hot air balloon fiesta. They have a helium balloons race to see who can fly the furthest. Every year these balloons travel east (carried by winds). There has never been a case where these balloons traveled west. North an south? yes but also with an eastern gradient with it. Also a rew years back we had several groups trying to circumnavigate the globe in a helium/ Hot air ballons. If you look at their flight paths it was always in a west to east direction. All this means is that the prevelent winds are usually west to east, and going faster that the earth is rotating in the same direction. With this being the case why would I have a shorter flight going agaist the wind than flying with the wind?

Al, I have not read the article you put a link to. Maybe I will change my mind afterwards, but at the moment I sticking with my theory

4. We are talking actual flight times, so time zones are not part of the question.

5. Stan I do not fully understand your input about always aiming left of a target. But I think it is proof that the earth rotation is a major factor determaining where and how you target your missle. That would mean that earths rotation must be taken into account, and thus could easily be part of the reason why flight time is shorter heading west than it was flying east.

6. coriolis effect? not sure where this might come in.

7. Stan in your first post you disagreed: "I have to disagree with your earth rotational speed causing any change in travel time according to your theory. If this were there the case-the rotational speed of the earth at our latitude is at or faster than the typical cruising speed of a commercial airliner." Normally when one is discussing speed it is in relation to the earth, (as if the earth is not moving at all). when I say that I am driving 60 mph, I do not include the speed of the earth in the equation.

8. If the rotaion of earth is not the answer, consider this; you have a person driving from the east coast to west coast and another driving from the west coast to east coast. Each starts at sunrise and stops at sundown driving at "equal speed". Will each driver have the exact same amount of time driving or will one have a longer period of time to drive?

Sometime the simple answer is the correct one. Unless someone can prove me wrong, I believe the answer is still due to the fact the earth is rotating west to east under the plane thus reducing the flight time to get from point A to B

Shawn
 
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it is due to the rotation of the earth.
Shawn, the rotation of the earth has nuthn to do with it. Otherwise i could be do'n hundreds of mph in me gyro. [ one way at least :), and always flyn backwards the other way. :(]
If it did, jets would only need to leave the ground, stay there, letn the earth rotate beneith it, the land wen the destination turned up.
Be we know that cant happen [ unless you go high enuff to be in space] coz the air we fly in is traveln round with it, so we must propel ourselves through it.

I recon your just flyn one way in a faster plane than your returning in. Thats pretty simple. ;)
 
Shawn: Hey...I am not the argumentative type. I dont want to turn "your" thread into something negative...ok?:D
 
Shawn: My fat finger accidently posted my previous message.


Anyway...I just want to say that there isnt any flying difference due to the earths rotation....or driving. I do know that airlines have scheduled routes...and if say they have extra built in time...like a couple of hours..they will save fuel and fly slower.....I mean why rush to get there and then such sit and wait when all that fuel could have been saved? On the other hand...they may have a route where they dont have much reserve to get there...so they are on high cruise....because missing the next leg is more costly.

The only other reasons have to be either different routes....and the winds.

As far as the earths spin effecting some artillery shells...it most certainly does because it is a "free projectile" Once it leaves its launch site...its bearing is set ...and the target either drifts towards or away from it.

For example...I live in Illinois...30 miles north of Champaign. There are artillery shells that will travel that far. Since I am north of Champaign...I am at a higher latitude. The equator being at 0 degrees latitude is going the faster....roughly 1000 miles per hour at the surface. The north pole is 90 degrees latitude and is going 0. Anyway....Champaign is south of me and is going faster than where my artillery shell launcher is. I therefore have to aim to the left ...or east of Champaign to hit my target. As the shell is lobbing in to Champaign to the east....Champaign is slowly catching up and if my calculations were correct...my target and my projectile will meet. Its again a free projectile and its "hangtime" , distance to target...and angle that its trajectory is crossing the lattitude lines all play into how much correction is needed. I do not know that information but someone that say is in the Army and does this stuff for a "killing" (bad play on words), would know.

Likewise if I missed my target in Champaign..and they fired back.....they are moving faster than I...and they would have to still aim to the left of me....or west of me. I would then slowly drift under the shell and if there calculations were correct.....I am toast.


Shawn...please believe what you want...just do some research...its an interesting topic. :yo:

Stan
 
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