Monday, 13 August 2012

How to Make Plastic Planes to Graphene Rockets?

This is what I picture a graphene rocket to look like.

I was listening to Bill Nye on the Nerdist podcast this morning.  Bill Nye is awesome and one of several reasons I decided to go into science (and also for potential superhero/supervillain capabilities).  Telling science to the everyday man and exploring new frontiers is something I like to do and something I learned from Bill Nye's shows.

One thing that I did not know about Bill Nye is that he worked for Boeing and he was fairly passionate about talking about making better spaceships.  On the Nerdist Podcast he mentioned that an airplane like a Boeing 747 is about 30% fuel whereas a rocket is about 70% fuel.  That is a lot of fuel to be sending to people and things to space.  So every extra kilo of baggage the astronauts take costs a lot of fuel (so you cannot take your favorite pillow to space).

To save on fuel you would need to get rid of extra weight for things that you cannot get rid.  This can be done with ipads to save paper weight of the navigation charts, better designed seats, and lighter people. 

It was interesting listening to Bill Nye talk about the space and his work with the The Planetary Society.  He talked  about plastic planes or carbon fiber planes that they are making at Boeing.  Eventually someone like techies Elon Musk at Tesla and Space-X or former Microsoft Paul Allen will make a plane or a rocket but instead of steal make it out of plastic.  In fact Paul Allen and a company called Stratolaunch are already in development of this plane and booster rockets will be made by Space-X.  Seriously, check out the story here.   I am all for the post Howard Hugh's era of making private aeronautics research and development.  More billionaires need to take the helm and take to the skies. 

But is plastic the best material?  Should we  do people trust plastic?  Advances in plastic have been huge since Dustin Hoffman was introduced to plastics in 'The Graduate' Can it withstand space? 
Are there better materials to go to space?  I thought of graphene.

Graph what?  Graphene is a new material being researched that has all the properties to make a great rocket ship.  It is strong, light and thin.   How strong, how light and how thin?

For example as quoted directly:

“It would take an elephant, balanced on a pencil to break through a sheet of graphene the thickness of cling film.” said Columbia University Engineering Professor James Hone; continuing, "Our research establishes graphene as the strongest material ever measured, some 200 times stronger than structural steel." (emphasis added) Source: Scientific American online

A graphene sheet is only one atom thick, so it takes 3 million sheets on top of each other to be the thickness of one millimeter!
It is so strong because it is made of Carbon atoms double-bonded together in a lattice. “It would take an elephant, balanced on a pencil to break through a sheet of graphene the thickness of cling film.” said Columbia University Engineering Professor James Hone; continuing, "Our research establishes graphene as the strongest material ever measured, some 200 times stronger than structural steel."
(emphasis added) Source: Scientific American online

A graphene sheet is only one atom thick, so it takes 3 million sheets on top of each other to be the thickness of one millimeter!  It is so strong because it is made of Carbon atoms double-bonded together in a lattice.  

Graphene would be an excellent material to be used for a rocketship of the future.  It is unbelievably light.  It is unbelievably thin and it is unbelievably strong.  

However, the future is can be far away depending on how fast the research can be conducted, and whether it can be mass produced.  A couple of years ago I went to a conference and learned that they were making repoducable sheets of graphene using In order to make these lattices you need to use graphene on interfaces.  A really cool method made by researchers at Northwestern University in Illinois made for several applications using Langmuir Blodgett monolayers.  Another paper using the same technique can be found here.

A group in Sydney has recently made graphene paper.  This is 10 times stronger than carbon fiber. 

The LB monolayers  simple device allows the graphene to be one molecule thick then made into a lattice of molecules.  These simple devices starting from a kitchen sink of a housewife in England will help us make the best rockets to thrust us into space.  Hopefully, the research in this area will be successful and we will get to the moon, to mars or beyond....

Wednesday, 1 August 2012

'Don't be Splashy' Olympic Syncronized Diving

I was watching Olympic synchronized diving and was cheering on the Canadians.  The men's and women's teams both won metals.  It was my first time waching this competition and was suprised that they really judge splashiness.  One way to stop splashiness is to change the posture of the divers by using rocktape to help them streamline into the water.  What causes the splashyness?

The antithesis to divers are bellyfloppers.  Everybody has probably belly flopped at some point (not everybody is an Olympic diver).  So what is belly flopping and how does water's properties play into making splashes?

Two factors play here: the compressive strength and the shear strength. The compressive strength (and oppositely the tensile strength which is related to the surface tension) of a material like water depends on the molecules. The shape of water molecules determines how they line up (or don’t line up) when under pressure and compressed to move closer together. Atoms in a body of water will try to find an equilibrium position and distance themselves throughout the material (in this case the ocean) to return to equilibrium. The compression strength is what makes the belly flop hurt and makes me cringe. Compressive strength is measured in dynes/cm2.

The shear strength is like the shearing force or rigidity. Shear strength is measured in dynes/cm2. Water has zero rigidity. Like if you were to turning a round jar of water with a fish in it--the jar turns but the water does not, and the fish is still facing the same direction. This is because the sides of the jar slide across the water without affecting it--water has no shear strength. Put gelatin in the jar and you have a material with shear strength--and the fish will turn with the jar (do not try this at home). In the case of the belly flopper, since he jumped with his whole body parallel to the plane of the water he confronted the in-compressibility of water mentioned above.

However, during training the Canadians and other divers are likely to suffer severe injuries if they attempt a new dive and spin out of control.  One example is the German diver Stephan Feck who during his 3 meter spring board dive hit the surface of the water with his back after failing a pike.  See horrific video here.

What the Feck?

At several points during the evolution of the sport people created better tools to make the once named fancy diving safer and more fun.  A tool called the bubble machine invented by Herb Flewwellyn (a Canadian) in the late 1960's makes diving a little safer.  It works by creating a mass of bubbles in the center of the diving well.  The bubbles break the surface tension of water to create a "softer landing zone" .  The compressibility of the water would still be a factor but the initial hitting of the water may relieve some of the energy needed to break the water.

So the next time you dive in water you put your hands in front to break the water as the Olympic swimmers do, and, if you do it right, you slide right into the water without pain--again because water has no shear strength. You also displace as little water as possible making less of a splash. Diving like this would make me cringe less.

(Some info was found here in this great explanation of seismic waves).

Why Micheal Phelp's Shaves Himself and Surface Tension in the Olympics

Water sticking to the surface of skin

I love swimming.  I have been swimming well since I was young.  Although I never really participated in any races I would consider myself a decent swimmer.  I was watching the Olympic swimming and was looking at how these swimmers break the surface of the water.  There are several forces at play that can make a break a swimmer.  These forces are the resitant (surface area contact with water) and propellant forces.  With underwater cameras and understanding these physical principles it is possible to make swimmers faster.

Frontal resistance - the greatest ally or downfall of a swimmer caused when the body rides too low in the water.  To elliviate this swimmers roller the body in the water to reduce the surface area of their body on the water.

Skin Friction- is the area where the water is in full contact with the skin to travel at 0 m/s^2.  One easy way is to do what most swimmers do is to shave themselves and use body lotion.  Micheal Phelps and the rest of the Olympians probably do   This can decrease the time by about 1 second for every length of the pool.  A second way used biomimetics from understanding the surface tension of fish.  This is mentioned later.

Eddy Resistance - is caused by poor swimming technique and riding low in the water so small vortexes are still bound to the swimmer after each stroke.  The swimmer will want to get rid of these small eddy currents to propel the forward faster.

Lift - the most important to swimming shows that the Bernoulli principle affects swimming stating that the speed of the fluid particle increases as it travels through a horizontal streamline.  The S shaped pattern when the swimmers arm passes over the bodies axis of rotation produces lift like a propeller.

If one were to think that the swimmers technique is fully optimized frontal resistance, eddy currents and lift should be optimized as well.  The one physical factor that is more difficult to change would be the surface area contact with the water and the breaking of the surface tension.  Can swimmers swim better underwater if  they have the ability to change the surface tension on their skin and suits?

Some swimmers discovered that they could kick underwater faster than they could swim on the surface. Those who were great kickers would kick almost the entire length underwater and then surface right before the turn, do a stroke and a turn and go as far as they could underwater on the next length.

The result of this was that the International Swimming community decided that swimmers were supposed to swim, not just kick and now, at all levels of swimming, there is a 15 meter rule. That rule came into existence about 10 or 12 years ago and it requires a swimmer to be on the surface by the time they reach 15 meters from the start or a turn. If you go past 15 meters underwater you are disqualified (DQ). You'll notice that most lane lines have one red marker about 9 yards from the wall ... that is the same as 15 m from the other wall.

So breaking the water surface reduces the speed in swimming.   The surface tension will make a difference of a few tenths of a second which is about the time that is needed to win or lose a competition.  This is a difference between gold, silver, bronze and invisibility in swimming.  So controlling surface tension is important.  Could a swimmer cover themselves in soap to reduce the surface tension?

 A second way that is even more popular today with rocktape and new materials is to use compression suits with seamless fabrics and using a fish skin riblet.  The compression suits reduce muscle wobble.  The fish skin riblet designed by Speedo made with repetitive grooves of tens of millimeters to one millimeter grooves which can reduce the friction resistance of a fluid.  In fact films of this kind are made by 3M and are used in yachting to reduce biofouling.  Possibly, a surfactant or biofoam could be applied on the front side of a swimmers body to reduce the surface contact.

Swimming pools have dividers in the lanes that have a disc that rotate when hit by a wave to dissipate the surface tension waves in a competitive pool