Tough Puzzle About Airport & Airplane

On Bagshot Island, there is an airport. The airport is the homebase of an unlimited number of identical airplanes. Each airplane has a fuel capacity to allow it to fly exactly 1/2 way around the world, along a great circle. The planes have the ability to refuel in flight without loss of speed or spillage of fuel. Though the fuel is unlimited, the island is the only source of fuel.
What is the fewest number of aircraft necessary to get one plane all the way around the world assuming that all of the aircraft must return safely to the airport? How did you get to your answer?

Notes:
(a) Each airplane must depart and return to the same airport, and that is the only airport they can land and refuel on ground.
(b) Each airplane must have enough fuel to return to airport.
(c) The time and fuel consumption of refueling can be ignored. (so we can also assume that one airplane can refuel more than one airplanes in air at the same time.)
(d) The amount of fuel airplanes carrying can be zero as long as the other airplane is refueling these airplanes. What is the fewest number of airplanes and number of tanks of fuel needed to accomplish this work? (we only need airplane to go around the world)

Replies

Anoop Kumar

I think 6 planes will be needed.😒

Edit:
Will explain if it is correct😉
Prashanth_p@cchi

ianoop
I think 6 planes will be needed.😒

Edit:
Will explain if it is correct😉
Ya, it's correct. Can you please explain now?
Anoop Kumar

I hope it is understandable 😁
Prashanth_p@cchi

ianoop

I hope it is understandable 😁
Grrrrrr...... Not for me at least!!!!!!!!
Anoop Kumar

I am showing how much fuel they have at each stages... propagation is from right to left. ABC will fly to right while DEF to left. time can be calculated that at what time they will fly.

that bent arrow _| show fuel after transferring to other planes. Finally plane A will complete the circle.
#-Link-Snipped-# , Is my answer correct ??
Ankita Katdare

Nope 6 is not a correct answer.
Anoop Kumar

Ok, then I think I got that... Until the A will reach to 3/4th. B& C will able to fill their tank and,
in my solution E & F can be replaced by B & C.
Only 4 planes required. right
Ankita Katdare

I am not revealing the answer. Let all CEans rack their brains and come up the best one.
Saandeep Sreerambatla

There is nothing mentioned about speed of the flight, so a flight can take less time to reach a point and another flight can fly faster but it cannot stay still in air 😀

so I think the minimum number required is 3. Took 1 hour of my time 😀
Saandeep Sreerambatla

Now tell us the answer 😀
Ankita Katdare

English-Scared
There is nothing mentioned about speed of the flight, so a flight can take less time to reach a point and another flight can fly faster but it cannot stay still in air 😀

so I think the minimum number required is 3. Took 1 hour of my time 😀
Yep. The correct answer is 3.

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Tough Puzzle About Airport & Airplane

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