Round the World Flight For Solar Powered Plane - PeachParts Mercedes-Benz Forum

Mistress · #1 06-26-2009, 04:20 PM

pretty cool stuff

http://www.independent.co.uk/news/science/roundworld-flight-planned-for-solarpowered-plane-1721067.html

Kuan · #2 06-26-2009, 04:33 PM

I wonder how many amp hours that 400kg of Lithium Ion batteries provides.

Phil · #3 06-26-2009, 05:16 PM

Look up the Helios airplane although I don't think they flew it that far.

MTI · #4 06-26-2009, 05:18 PM

Wonder how good the cells are under a full moon.

t walgamuth · #5 06-26-2009, 11:42 PM

I was thinking he would fly always following the daylight. Maybe that's easier said (sitting here at my computer) than done.

Palangi · #6 06-26-2009, 11:46 PM

Quote:

Originally Posted by t walgamuth

I was thinking he would fly always following the daylight. Maybe that's easier said (sitting here at my computer) than done.

Without actually doing the math, I would guess that you would need to be going at around 700 mph in order to avoid running out of daylight.

Chas H · #7 06-27-2009, 12:02 AM

Quote:

Originally Posted by t walgamuth

I was thinking he would fly always following the daylight. Maybe that's easier said (sitting here at my computer) than done.

At the equator it would require about 1000mph. The speed requirement would decrease as one moved towards the poles if we disregard the effect of the earth's axis tilt.

RML · #8 06-27-2009, 12:20 AM

Quote:

Originally Posted by Palangi

Without actually doing the math, I would guess that you would need to be going at around 700 mph in order to avoid running out of daylight.

My guess is that it would have to be faster than that. The circumfrence of the earth is about 25K miles, and if you divide that by 24 hours , you get 1,042 mph that the earth is going around. So to stay in the same spot, you have to be going that speed. But you do not fly on the surface of the earth. Lets say you fly at 10K feet. That is about 2 miles up so you add 2 miles to the diameter on each side, and that makes the circumference jump to 37,700 miles. To cover that and stay in the same place, you need to be going 1,571 mph. But you don't have to stay in the same place unless you always want the sun right overhead. You can extend the trip and lower the speed by starting out in mid morning and landing in late afternoon. So that will bring the speed down to around 1,257 if you take 30 hours to make the trip instead of 24.

Seems to make sense to me but I welcome any corrections to my logic.

Chas H · #9 06-27-2009, 12:33 AM

If we use 25,000 miles as the circumfrence (not the diameter) and divide by PI (3.14) we get 7962 miles as the diameter of the earth. We then add 4 miles to that and multiply times PI we get 25,013 miles. The speed to cover that in 24 hours is still 1042 mph.

RML · #10 06-27-2009, 12:36 AM

Quote:

Originally Posted by Chas H

If we use 25,000 miles as the circumfrence (not the diameter) and divide by PI (3.14) we get 7962 miles as the diameter of the earth. We then add 4 miles to that and multiply times PI we get 25,013 miles. The speed to cover that in 24 hours is still 1042 mph.

Whoops, I meant the circumfrence is 25K. I'll edit it.

RML · #11 06-27-2009, 12:41 AM

Quote:

Originally Posted by Chas H

If we use 25,000 miles as the circumfrence (not the diameter) and divide by PI (3.14) we get 7962 miles as the diameter of the earth. We then add 4 miles to that and multiply times PI we get 25,013 miles. The speed to cover that in 24 hours is still 1042 mph.

Yep. You are right. I wasn't watching my numbers carefully. I added 4K miles to the diameter instead of 4.

Chas H · #12 06-27-2009, 12:42 AM

Quote:

Originally Posted by RML

Whoops, I meant the circumfrence is 25K. I'll edit it.

But adding 4 miles to the diameter of the earth won't give 37,700 miles in circumfrence.

t walgamuth · #13 06-27-2009, 09:41 AM

I have a pretty strong feeling that that solar plane will not do 1000 mph!

RML · #14 06-27-2009, 10:19 AM

Quote:

Originally Posted by t walgamuth

I have a pretty strong feeling that that solar plane will not do 1000 mph!

Maybe if you add a few auxiliary diesel engines.

Palangi · #15 06-27-2009, 12:09 PM

Quote:

Originally Posted by RML

My guess is that it would have to be faster than that. The circumfrence of the earth is about 25K miles, and if you divide that by 24 hours , you get 1,042 mph that the earth is going around. So to stay in the same spot, you have to be going that speed. But you do not fly on the surface of the earth. Lets say you fly at 10K feet. That is about 2 miles up so you add 2 miles to the diameter on each side, and that makes the circumference jump to 37,700 miles. To cover that and stay in the same place, you need to be going 1,571 mph. But you don't have to stay in the same place unless you always want the sun right overhead. You can extend the trip and lower the speed by starting out in mid morning and landing in late afternoon. So that will bring the speed down to around 1,257 if you take 30 hours to make the trip instead of 24.

Seems to make sense to me but I welcome any corrections to my logic.

Yes, just a quick mental calculation would be, earth is approx 24k miles in circumference, therefore it would take approx 24 hours at 1000 mph to circumnavigate. That assumes, however, that you would stay at the same local time throught the trip. Take off at noon, always flying at noon, land at noon, for example.

The logical thing to do would be to depart westbound at sunset. The sunset terminator, which is advancing westward at 1000 mph would outrun you if you were going, say, 700 mph. Eventually the sunrise terminator would catch up to you, but, in the meantime, you would always be in dayylight. The exact speed required to make that happen could be calculated, but, doing so would make my head hurt.

It's all just theoretical nonsense anyway. Westbound would be against the prevailing winds, so you would be screwed anyway.