Glider & Dethermalizer Timer Build

Glider & Dethermalizer Timer Build

Day 1 building a Georgia Swift 19 balsa glider and a dethermalizer timer to release an airbrake flap. The flap is needed because this type of glider can catch a thermal draft and stay up for ten minutes or longer. The timer will release the crash landing flap after about a minute so the glider doesn't fly away forever!

All the glider parts, and extra stuff (like Silly Putty!) for the dethermalizer timer. I went with Loctite CA glue instead of Elmer's. The Loctite is like Crazy Glue, only it's a little bit gel-like in consistency, instead of watery, making it easier to apply without running everywhere.

Here are the wings, boring and flat. I shaped each wing using 80 grit sandpaper, much like shaping a surfboard.

The wing airfoil profile should be a Wittman SS4 "supersweep" shape. The wing is thicker in the center, thinner at the front of the wing, and paper-thin at the trailing edge. Ron Wittman took the balsa glider world by storm the year I was born, using his blunt-nosed, high in the middle wing shapes. His glider stayed up for almost 55 seconds. He set a world record!

The 'preferred' method of shaping is to lay a line of pins in an arc from tip to base denoting the high spot. Then you sand away from that. I used a drawn line. The ruler goes from a marked point on the tip to a marked point where it touches the leading edge. Then from that mark to the base. This is very easily reproduced on the other wing by just transfering the two mark points--then you just connect them with the ruler.

The leading edge is getting rounded off.

The wings started out as balsa "planks" that were uniform thickness. Much like a popsicle stick when viewed edge-on. Here you can see the airfoil form starting to take shape.

Here's where it gets totally awesome: the wings join in a 'V" shape at the center. Then I cut off the last 1/3 of each wing and sanded those edges so that when they were re-joined back in place they'd also form a "V" shape. The wings as a whole, also aim upward, while the nose points down. Kind of like it you're driving down the road and the front hood of your car opens up--it'll try to fly away: and this forms a dihedral wing. Actually I think this may be a double-dihedral (or maybe even a triple with all the Vees?" My radio control plane has dihedral (upswept) wings on it. Dihedral makes it harder too steer (which is why jet-fighters have zero dihedral) but it makes the craft float on the air, almost like a hot-air balloon. Very little effort is expended in getting an aircraft with lots of dihedral angle in the wings up in the air and keeping it there--a jet figher on the other hand doesn't glide, they tend to fall out of the sky on lose of power. Basically jet-fighters are like flying a cinderblock, given a strong enough jet engine it'll go up. If that engine conks out it falls almsot straight down. This design is the opposite of that!

Rudder joined to the rear of the fuselage. I kinda screwed up here. I  shaped the sides of the fusealge really, really thin. Almost as thin as the rudder. This severely weakens the rear, although later on I glued carbon fiber strips along the sides, which severely  strengthened, so it worked out.

Here's another photo of the really thinned-out rear fuselage. You can see here that the rudder and the fuselage are the same, near paper-thin thickness!

I located the area under the wing where the center of gravity should be, and I poked a nail through it sideways.

I then balanced the plane on an open vice on this nail. The more clay I added to the nose, the more forward it rolled. Like a teeter-totter! I got it pretty well balanced with yellow clay on the nose. After I add the dethermalizer apparatus I'll have to re-balance, but that's just adding or removing clay from the nose.

Carbon fiber strengthening strips. I cut them short so I could add extra pieces to the ultra-thinned out tail section.

The nose slopes down, and the wings point upward: dihedral. Then the wings "V" up at the center and each winglet tip. Plenty of lift!

Here is my new baby completed and test flown in one evenning! You can see the nose and fuselage sloping downward while the wings are angeled backwards. You can also see in the photo the three Vees: center and each wing tip.

So, how does it fly? Well, it's 1 degree Farenheit outside and windy and snowy. I've seen videos posted by the owner of Georgia Balsa Gliders posted on YouTube where he lobs it up into the air and it catches a thermal and stays up for quite a scary amount of time! I went outside and tossed this plane as weakly as I could, like dumping a kitten onto a bed for a nap--the plane sailed like a laserbeam at a (luckily) low and decreasing incidence to the ground. I have no doubt that if I chucked this glider with the same vigor I'd use on a regular paper airplane I'd be lamenting the fact that this thing entered the stratosphere and sailed out of sight! It really wants to glide up and away!!

The Dethermalizer Timer

I found many plans online for "Silly Putty Dethermalizer Timers" that were similar. Martin Gregorie has a fantastic how-to build guide online with tons of background information. The best pictorial build guide online is by Tony Matthews. This is where I got my plans from. I modified the plans and workflows a little to suit my habits--also my end cap where the trigger arm attaches has a 1/8" tube over the 3/32" tube. I did this for looks (since I was having fun!) but that adds unnecessary weight and also makes the trigger end the same width as the rest of the assembly so it may rub against the fuselage if you're not careful on installation. The extra tube there does look awesome and really made it easy to drill the hole for the trigger. Without it I'd have been drilling directly into the 3/32" tube which would be a real bummer.

As you know from previous posts I've manufactured my own various non-newtonian liquids and putties in the past, but I went with the store-bought variety: peach putty in a red egg.

I also picked up three telescoping sized aluminum tubes: 1/8", 3/32" and 1/16" outside diameters. I cut them easily by rolling an Xacto blade on them and they eventually go shooting off.

Cutting them all to shape.

Crush the last 5/16" of the 1/6" tube into a flat paddle.

The paddle, which will be swirling within the Silly Putty. This will do two things: slow the timer's spin rate; and give a very consistant spin rate. It's a timer after all. It will be powered by dental brace rubberbands. You can get different sized bands for different pull strength-which means different amounts of time before the timer goes off.

A tiny piece of 3/32" tube goes over the paddle tube to act as a bearing.

Here's the paddle tube and bearing tube assembly placed inside the big piece of 1/8" tube. You can see the paddle inside. The paddle area will be filled with Silly Putty and then capped off.

My father gave me this awesome mini-vice today! It's on a wooden base with three long strips of wood. The outside two act as regular legs. the third one can be clamped into a larger vice--like it is here. Brilliant!

Not to get too confusing, but that silver drill tool is also called a vice. It's a 'pin-vice' that holds tiny drill bits the size of a pin. Spin it in your fingers and you can drill stuff. I've used this one before--it was particularly handy when I was building my submarine (featured in my other blog about the U-2540 Wilhelm Bauer) and when I was making a teeny-tiny ship in a glass bottle.
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I cut a small safety pin apart with wire cutters to get the rubberband holder / trigger part.

Packing the paddle end of the tube with Silly Putty. This turned out to be the hardest part!

The open end of the tube was filled with Silly Putty. Turning the trigger to set the timer made the Silly Putty run out of the tube. I need a plug. I had a dowel that fit, but the Silly Putty kept squeezing past it! So I took a wooden match stick and rotated it into the tube.

Here's a photo of the shaped match stick. It's only about 3/32" long. I cut if off and then glued and hammered it into the Silly Putty end of the timer assembly.

Here's the finished timer. What a beauty! A rubberband pulls on the trigger arm. The Silly Putty inside slows its turning. Eventually the arm rotates enough and the rubberband falls off--this frees up a dethermalizer / airbrake flap which causes the glider to slowly fall out of the sky. Since I can't turn off the wind-I have to turn off the aerodynamics of the glider to get it out of the sky.

The paper thin tail section of the plane warped as it was drying from it's coat of sealant. It was getting less and less warped as it dried, but for good measure I found a metal plate and flatted the tail using two huge and heavy magnets I took off some old stereo speakers a neighbor threw in the garbage.

There's the flap I cut out from some roof flashing metal. You could also just use some metal from a tin can--which might be stiffer and better. It'll be mounted on the side of the fuselage. The tail-end will be glued down to act as a hinge. The end nearest nose of the glider will not be glued. It will be held down by a dental rubberband attached to the dethermalizer timer. Once the timer goes off and the rubberband slips away the flap (which is facing forward into the wind) will be free to flap out sideways and cause the airplane to (softly) crash land. This setup keeps the plane from flying too far away.

That's quite a day's worth of work! I originally didn't care about the glider and just wanted to build a dethermalizer timer. Now that I built the glider I really like it and don't want to cut into it to mount the timer and flap! But I'm afraid to fly the glider without one. Next Sunday I'll work on this again and decide what to do.

Check back here for either: a video of my timer-less glider sailing out of sight forever; or of my beautiful glider with the dethermalizer apparatus hacked onto it.

Decisions, decisions...

Throw it to me! I can catch it good. 

Non-Newtonian Fluid is the Best Kind of Fluid

Non-Newtonian Fluid is the Best Kind of Fluid

In my continuing assault on Isaac Newton I will demonstrate how boring old Newtonian fluids (like water) are less fun than non-Newtonian ones. First, we need to get our hands on a non-Newtonian fluid.

To make a non-Newtonian fluid we can just mix laundry spray starch and white glue. This will make a shear-thickening non-Newtonian fluid. Under stress it thickens and hardens (increases viscosity), once the stress passes it turns into a runny liquid. Put it in a cup and its like white glue you can stir with your finger. Poke your finger into the cup forcefully and it will harden into a single blob and you can pull it out of the cup!

Here's how quickly it is to make, it's actually easier without the gloves-they're too slippery to get a good gauge on the mix:

Here's my non-Newtonian fluid in action. Slap it and it hardens enough to let me peel it up off the plate. Wait a second and it'll drizzle down as a liquid:

There are many variations of non-Newtonian fluids besides shear-thickening ones.

Ketchup is a shear-thinning non-Newtonian fluid, which is why people smack (shear) the ketchup bottle to get it to thin and flow out faster. Xanthum gum is added to ketchup for just this effect.

If you put this spray starch and white glue mixture in a ketchup bottle the only way to keep it from pouring out would be to keep smacking the bottle! If you wanted it to thin and flow faster your just leave it alone for a few seconds. If you slap it hard enough it will instantly harden and break into two pieces, only to flow back together of left alone for a few seconds.

It seems pretty weird, but I've dealt with having a non-Newtonian fluid and the problems that it can cause:

I play a variety of bowed instruments. Rosin is used on the bow to let it grab the strings of the violin, cello or as in the photo above a double bass viol. The rosin looks and feels like a cube of yellowish glass:

This is the harder rosin I've used for years, but recently I started playing the huge upright double-bass which required me buying newer, softer rosin. It's in the red canister next to the violin. The softer rosin seemed like regular rosin: hard, produces a white powder when rubbed with the bow and will shatter into a zillion pieces if hit with a hammer; however you leave the canister on its side after a few days the seemingly glass-like rosin will ooze out. Leave it as a blob on a shelf and it will slowly pancake out: spreading and flattening, and eventually oozing off the edge.

Now, some people will tell you that regular old glass is a fluid that oozes over time, but they're wrong. Glass is a solid, although it isn't a crystallized solid so it's an amorphous solid. Crystals are rigid lattices of ordered molecules. Fluids and gases are unlatticed unordered molecules. Glass is unlatticed, unordered yet rigidly bound. Glass is a solid.

Most rosin for instruments is a solid, so solid on fact that it sometimes crystalizes. However bass rosin is much softer relative to regular rosin-although if you found a piece on the sidewalk you'd probably assume it was a chunk of old, broken glass.

Common myths: old glass windows are thicker at the bottom because the glass oozed down. Wrong: the spun old glass and cut it, the outside edge was always thicker and it was installed thick edge lower. A glass shelf will bend in the center over time so it's an oozing liquid. Wrong: it bends for the same reason wood shelves bend, it was too thin and/or too overloaded or gravity just got the best of it.

Polymers are repeating molecular units. They tend to create semi-crystalline structures and glasses. It tends to make things "plasticy" and in fact it gives the name for polystyrene is polymer of styrene (styrene being obtained from benzine).

What else has a crystalline structure? The starch spray in our non-Newtonian fluid. It has a semi-crystalline structure, that helps bind the glue into big molecules that are a polymer. Starch itself is considered a polymer. Adding a little borax powder* to the mix would make it a stronger polymer--strong enough that it would stop being a thinning/thickening liquid and become a rubber-like blob that you could throw and bounce off the walls. If you add an enzyme it will break the polymer up into smaller units (monomers) which changes its properties. Stringing together units of silicon yields a semi-liquid silicon polymer, which we call Silly Putty!

*Borax powder is sodium borate a natural compound of the element boron, which is what you want to get in the laundry aisle.

Boric acid is hydrogen borate is an acidic form of borax that is either a natural compound or manmade using the element boron with sulfuric or hydrochloric acid; as such it is acidic. Borax crystals are usually crystallized boric acid. They are sort of not the same. Kind of like ice is frozen water and good for putting in soda, ice dipped in acid is not quite the same.

Boron is B
Boric Acid is H3BO3

Borax is (NA2B4O7)(10H2O)

When dry boric acid crystals are added to water it grabs electrons and becomes weakly acidic. This weak acid is used in eye washes and hygiene products to combat yeast.

You'll also remember boron in its elemental form has awesome properties when used to lace blocks of paraffin wax during out experiments with slowing down radioactive neutron particles in my previous post "My Radioactive Dime".

Where else is boron/borax used? Taxidermy!

This is part of my Game fowl Collection: photo-books by Hiro; my bird Alouicious (named after the teddybear from Brideshead Revisited); and copies of Feathered Warrior (a catalogue where you can buy fighting spikes and the live-fertilized eggs of *past* fighting champions). 

Alouicious is actually from an organic market in Rochester Hills - not a fighting bird (so if you were upset when you thought he died in a cockfight, but relieved he was just normal food-then you're a hypocrite, unless you're vegan). LOL.

Here's a pic of my room-mate Boris the Book Boar visiting Melvindale Public Library during a charity event.  He came all the way from the Black Forest in Germany!

As you can see, boron is very useful! But enough of boron for now, it's time to get back to starchy polymers...

Boron has an incomplete set of electrons (in a compound) and seeks them out to bond with. This gives boron (not boric acid) many uses in the adhesives industry, including mixtures involving our good old friend starch! I see this all the time (I'm a librarian) in bookbinding pastes. One great glue for paper (used to make cardboard poster tubes) made from a water soluble synthetic polymer is polyvinyl alcohol (PVA) with boric acid added to it. 

Usually polyvinyl alcohol (PVA) has a formula of (CH2CHOH)n), but this particular chunk of PVA is actually:

 (-(CH2CHOH)n-(CH2CHOOCCH3)m-)

PVA is sorta weird in that it's not made up of chained monomers, it's polyvinyl acetate that is polymerized, and then the acetate is converted to alcohol! It's very bouncy:

PVA is  (CH2CHOH)n or it is -(CH2CHOH)n-(CH2CHOOCCH3)m-

Glucose is C6H12O6

Starch is C6H10O5

As a side note: the specific gravity of this PVA ball is 1.24 according to the MSDS (Material Safety Data Sheet) provided by the manufacturer, Chang Chun Petrochemical. It sinks in water, but if you tip the bowl it's in it only slowly rolls to the lower side.


Here's a weird enzyme vs polymer test: chew a saltine cracker. Your saliva will break up the polymers and the crackers will get sweeter and sweeter as you keep chewing (and not swallowing) and adding more crackers. The monomer of starch is glucose. Glucose is a simple sugar. Simple sugar is sweet. It's the enzymes in your saliva (not the acids) that do this.

As a polymer, starch tastes like bread or potatoes. Break it up into its glucose sugar monomers and it's sweet! Glucose attracts water around it. Starch just attracts other starch around it. Glucose grabbing water can cause swelling and other problems-especially in the bloodstream of humans. It also causes plants (which store sugar/energy in the form of glucose) to need more water to make the glucose happy. The result is thirsty plants.

Many plants have wised up and stored their glucose in the form of longer chains of starch: the plants aren't so thirsty and the starch isn't bothered by whatever water is in the plant (too much water can mess with the glucose storage). Glucose in plants and animals calls for a balancing act with the amount of water, starch doesn't really care so much.

So...I guess have to find someone besides Newton to blame for the constant barrage of cantaloupes "oozing" off the glass table? Cantaloupe polymerization via face rubbing? I don't want to be taxidermied. Meow.

Oink!