Understanding Ho Ho Ho

How DOES he do it??

It used to be that people took it on faith that Santa Claus and his reindeer could fly. Long before we became the skeptics we are today, no one really cared how the big guy accomplished his seemingly impossible trek through the atmosphere every Christmas Eve.  We just believed.  But, alas, times have changed.  Now people want to know exactly how – or even if – Santa does it each year. And the only way to keep them happy is to demonstrate through reason, logic, and pure, hard science that maybe, just maybe, old St. Nick can actually get in the air with his sleigh and reindeer, zip around the globe and deliver his toys of joy.  So, I decided to look at what Santa purports to do each year, and realized he’s harnessed some basic rules of physics, aerodynamics, thermal dynamics (my favorite), a little reindeer biology. Let’s just say it’s a combination of air speed, lift, fairy dust and the magic Christmas spirit.  (the exact combination is a trade secret that Santa does not even share completely).

His Sleigh
It all starts with the sleigh.  While most contemporary artists draw Santa’s sleigh as the classic 19th century wooden carriage, that can’t be accurate. It just doesn’t fly, you might say.  In order to get airborne, I found out the sleigh is constructed of super-thin aluminum alloys (Santa calls it “elfluminum”) that cuts down on weight (and when Santa’s inside, reducing weight is very important).

Very important is the curved front end, that creates lift – putting more pressure under the sleigh than over the top.  To make sure the wind beneath his sleigh exerts more pressure than the wind above it, Santa has designed it much like the folks at the airlines – curved on top and flat on the bottom. That design increases the air speed above the wings, which is vital since, faster air speed results in lower air pressure and contributes to that much-desired lift.

It’s called Bernoulli’s Theorem https://en.wikipedia.org/wiki/Bernoulli%27s_principle, discovered by 16th century Swiss mathematician Daniel Bernoulli. His observations of fluid dynamics are at the heart of flight lift.  But let’s just say someone else a little further to the north might have known about it centuries earlier.

With the properly designed sleigh underneath his jelly belly and bag of endless toys, Santa then has to generate enough speed to get the lift needed to take off. Airplanes do it with powerful engines. But engines, of course, are very loud and would wake the children of the world as Santa makes his rounds.  That’s where his reindeer come in.

The Reindeer
Reindeer are hearty enough to survive conditions at the North Pole but quiet enough so as not to disturb his young customers as the big guy flies over their homes and lands on their rooftops.  Normal reindeer can run fast – by animal standards, at least – about 35 mph. That’s a lot slower than the 150 mph threshold when most jumbo jets take off but, of course, the reindeer have something else helping them out – their antlers.  These appendages also create lift.  With the air rushing underneath those antlers at a higher pressure than the air above, the nine reindeer can generate lift of their own and get airborne at lower speeds than otherwise needed.

Once in the air, some other parts of the reindeer’s anatomy help Santa stay up without crashing or destroying all those toys. On the ground, the reindeer generate the force needed to move forward by stomping their extra-wide hooves as they run. Normally, that force only sticks around for as long as there is something – like the ground – to react to the force of the reindeer’s kicking.  But this is Christmas, so, once in the air, to help keep them airborne, some scientists observe “good for kicking and paddling through the air.”  Scientists also think that the reindeer’s hollow hair is something special – which helps insulate their bodies in winter time – and allows the wind to blow right through the animals’ fur without creating that dreaded drag or slowing Santa down.

The Delivery
Based on census data, there are about 2 billion children (persons under 18) in the world. But, since Santa doesn’t visit all the children, that reduces his workload to about 15% of the total – 378 million according to Population Reference Bureau. At an average census rate of 3.5 children per household, that’s 91.8 million homes – assuming of course there is at least “one” good child in each home.

Santa has 31 hours of Christmas to work with, thanks to the different time zones and the rotation of the earth (he travels east to west which seems logical). This works out to 822.6 visits per second. This is to say that for each household with good children, Santa has 1/1000th of a second to park, hop out of the sleigh, jump down the chimney, fill the stockings, distribute the remaining presents under the tree, eat whatever snacks have been left, get back up the chimney, get back into the sleigh and move on to the next house. Makes perfect sense to me.  Assuming that each of these 91.8 million stops are evenly distributed around the earth (which, of for the purposes of our calculations we will accept), we are now talking about .78 miles per household, a total trip of 75-1/2 million miles, (not counting “necessary” stops to do what most of us must do at least once every 31 hours), plus feeding the reindeer.

This means that Santa’s sleigh is moving at 650 miles per second, 3,000 times the speed of sound. (For purposes of comparison, the fastest man- made vehicle on earth, the Ulysses space probe, moves at a poky 27.4 miles per second) but hey, he’s Santa.

The payload on the sleigh adds another interesting element. Assuming that each child gets one small gift (2 pounds), the sleigh is carrying about 321,300 tons, not counting the reindeer or Santa, who is invariably described as “overweight”. On land, conventional reindeer can pull no more than 300 pounds (we’d need 214,200 reindeer).  This is precisely why Santa sprinkles them with magic Santa dust.

Basic Science Proves it All
So, let’s see – over 300,000 tons traveling at 650 miles per second creates enormous air resistance – this will heat the reindeer up in the same fashion as spacecrafts re-entering the earth’s atmosphere. A lead pair of reindeer would absorb 14.3 QUINTILLION joules of energy. Per second. Now, of course normal reindeer could not withstand this amount of heat (the entire reindeer team would be vaporized within 4.26 thousandths of a second) – that’s why Santa put Rudolf and his shiny red nose at the lead. (Duh!)

And, if Santa didn’t have his special red suit that Mrs. Claus made for him, he would be subjected to centrifugal forces 17,500.06 times greater than gravity. A 250-pound Santa (which seems ludicrously slim) would be pinned to the back of his sleigh by 4,315,015 pounds of force. But of course, he’s protected by his magic suit, and the air barrier around him (second duh!)

According to Arnold Pompos, a really smart guy at Purdue University, Santa would have to travel a total of 160,000,000km – further than the distance from the Earth to the Sun –  at a speed of 4,705,882km/h, far slower than the speed of light, but still fast enough that the air resistance would likely to vaporize Santa, along with all the children’s gifts… if he wasn’t riding a magic sleigh of course – (third duh!)

All in all, I still enjoy the love and joy and magic of Santa and his reindeer – on behalf of all the KHT Elves, loving every minute of your PIA (Pain in the @%$) Jobs, Merry Christmas to All and to all a good “flight”

To track Santa, go to www.noradsanta.org .

 

 


 

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