On your marks..Get set..Go

This week, the challenge was to build and test junk-mobiles for speed and durability.

The first phase of this task was to put together the buggy by making wheels on axles and attaching them to the chassis or body. A wheel and axis unit is a simple machine-but it's not necessarily simple to make it work well as part of a buggy!

image from http://www.education.com

Lots of design choices were made here- the number, size and positioning of the wheels and axles, the type of axle and the shape, size and material of the chassis. In our design brief we asked the kids to make sure the wheels and axle could freely spin and that the whole buggy would be light but sturdy.

Now to get down to testing. Ready, set, go!! What happens when we launch our buggy down an incline? There's the sheer delight of making something that moves of course. It's equally fun to see what happens when you smash your truck into the wall at top speed.

Some vehicles do unintended stunts! A complete 180 degree turn or interlocking wheels for the girls' team trucks. One intrepid truck climbs on top of another one. This can be fun, but the design brief is to try and make the buggy to go straight. Time to make sure the axles are parallel and the wheels aligned.

The classic wonky wheel problem is common. These CD wheels are nice and big -which means they have a higher gear ratio than little wheels. Their lightness is generally good too-because the buggy is not weighed down by its wheels. But-there's a bit of an issue with their tendency to flop over.

This triangular chassis helps to stabilize the axles and makes this large buggy quite successful.  

In this car. a design solution was using foam blocks to keep the wheels straight. Unfortunately this was not sturdy enough to support the chassis without the wheels tilting. Sometimes troubleshooting can be maddening -especially when you are running out of time. A veritable tape marathon to keep the CD wheels straight and non-wavering.

In this car, lateral movement of the axles makes the buggy turn corners.

In the second phase of this challenge we asked the kids to add a jet propulsion engine to their buggy. A balloon taped up to a straw is attached to the back of the chassis and works rather like a rocket booster. In theory, the air escaping from the straw-provides thrust which pushes the buggy forwards.

Perhaps two balloons will work better than one?

Best is a balloon with a short straw (to minimize friction for the escaping air). The placement of the balloon (and the direction the nozzle points in) is also critical to how well it works. The elastic quality of the balloon makes a difference too. Some types of balloons work better than others.

This car was light -and low on friction- and sped some way with this nice short balloon nozzle.

The finishing touch: add your own logo to the racing car to give it a personal touch. This was an great workshop of testing and improvement. Well done kids.

These design workshops are made possible  by the Toronto Arts Council.

Zip away!

In this week's session there were three small design challenges. We built mini zip-mobiles, zip carriers and zip target droppers.

Time to build a zip-mobile. The challenge: make a sturdy structure that will fly down the zip line in less than four seconds using a paperclip, 2 straws, 2 sticks, 2 washers, tape and scissors. To make a device that zips, consider what arrangement will avoid too much friction or drag and think about how your centre of gravity will affect the flight.

Most of the students easily figure out which material should be in contact with the zip line so that the zip-mobile slides quickly. The second challenge: now modify your zip-mobile to make a zip carrier that will transport a ping-pong ball down the zip line. You are given a cup as additional material. 

Our third challenge was a complex design problem. The students are asked to modify their zip carrier to transport a marble down the line and to drop the marble on a target part way down. This has to be done without touching the carrier directly. There are several ways to tackle this challenge, but all involve some serious lateral thinking!

One team tries a remote string release mid flight. In multiple test runs they discover that the release needs to be before the cup is above the target. This helps because the marble is already moving forward along the zip line and moves in a curved trajectory (not a direct line down) once it is released from the cup

Maybe it's better to release the ball from a trap door in the cup rather than using a tipping mechanism? After some experiments with vibrating the carrier mid flight, one group decides to stop the carrier and then pull out a lower release pin (without touching the cup). Ambitious plan.

One student realizes that if she ties a string from the release point to the bottom of the zip-mobile it will tip the cup at a set point and release the marble towards the target. This is an elegant hands-off solution that needs some refining to make it reproducible.

And finally, it's race time. Which designs move faster and why? How does their shape and weight affect their speed? And how do friction and drag slow them down? But most of all, why can't you tell that was not a tie!

Ready, set, ZIP!

This Fall we've played, picnicked, illuminated, streetscaped, posed, modelled, chored and shopped. And finally, we zip into the Holidays!

In our final sessions there were three small design challenges. We built mini zip-mobiles, zip carriers and zip target droppers.

Time to build a zip-mobile. The challenge: make a sturdy structure that will fly down the zip line in less than four seconds using a paperclip, 2 straws, 2 sticks, 2 washers, tape and scissors. To make a device that zips, consider what arrangement will avoid too much friction or drag and think about how your centre of gravity will affect the flight.

Most of the students easily figure out which material should be in contact with the zip line so that the zip-mobile slides quickly. 

This zip-mobile uses the sticks horizontally almost like wings. The design is symmetrical around the central attachment point which minimizes rotation.

Durability becomes an issue for this designer who wants to build a transporter for her stuffies at home. How can I make something really strong from such delicate materials? 

The second challenge: now modify your zip-mobile to make a zip carrier that will transport a ping-pong ball down the zip line. You are given a cup as additional material. 

Our third challenge was a complex design problem. The students are asked to modify their zip carrier to transport a marble down the line and to drop the marble on a target part way down. This has to be done without touching the carrier directly. There are several ways to tackle this challenge, but all involve some serious lateral thinking!

One team tries a remote string release mid flight. In multiple test runs they discover that the release needs to be before the cup is above the target. This helps because the marble is already moving forward along the zip line and moves in a curved trajectory (not a direct line down) once it is released from the cup.

Some of our young designers came up with a solution where the carrier cup is tipped as it smashes into a barricade. After some testing it becomes apparent that it's hard to get reliable accuracy when the cup is stopped at top speed.  The marble usually comes flying out at random sides, occasionally hitting your friends! Time to rethink the prototype…

Maybe it's better to release the ball from a trap door in the cup rather than using a tipping mechanism?
After some experiments with vibrating the carrier mid flight, one group decides to stop the carrier and then pull out a lower release pin (without touching the cup). Ambitious plan.

And finally, it's race time. Which designs move faster and why? How does their shape and weight affect their speed? And how do friction and drag slow them down? But most of all, why can't you tell that was not a tie!

            Thanks kids, for a creative and lively Fall session.  Hope to see you in 2016.

Ready, Set, Go?

This week, the challenge was to build and test junk-mobiles for speed and durability.

The first phase of this task was to put together the buggy by making wheels on axles and attaching them to the chassis or body. A wheel and axis unit is a simple machine-but it's not necessarily simple to make it work well as part of a buggy!

image from http://www.education.com

Lots of design choices were made here- the number, size and positioning of the wheels and axles, the type of axle and the shape, size and material of the chassis. In our design brief we asked the kids to make sure the wheels and axle could freely spin and that the whole buggy would be light but sturdy.

Now to get down to testing. Ready, set, go!! What happens when we launch our buggy down an incline? There's the sheer delight of making something that moves of course. It's equally fun to see what happens when you smash your truck into the wall at top speed.

Some vehicles do unintended stunts! A complete 180 degree turn or interlocking wheels for the girls' team trucks. One intrepid truck climbs on top of another one. This can be fun, but the design brief is to try and make the buggy to go straight. Time to make sure the axles are parallel and the wheels aligned.

The classic wonky wheel problem is common. These CD wheels are nice and big -which means they have a higher gear ratio than little wheels. Their lightness is generally good too-because the buggy is not weighed down by its wheels. But-there's a bit of an issue with their tendency to flop over.

In this car. a design solution was using foam blocks to keep the wheels straight. Unfortunately this was not sturdy enough to support the chassis without the wheels tilting. Sometimes troubleshooting can be maddening -especially when you are running out of time. 

Here's one way to improve the wobbles. Remove the heavy body. And use attached wheel hubs. This car has a nice streamlined shape. Impressive how this designer worked his way through the design challenge.

A veritable tape marathon to keep the CD wheels straight and non-wavering.

In the second phase of this challenge we asked the kids to add a jet propulsion engine to their buggy. A balloon taped up to a straw is attached to the back of the chassis and works rather like a rocket booster. In theory, the air escaping from the straw-provides thrust which pushes the buggy forwards.

Perhaps two balloons will work better than one?

Best is a balloon with a short straw (to minimize friction for the escaping air). The placement of the balloon (and the direction the nozzle points in) is also critical to how well it works. The elastic quality of the balloon makes a difference too. Some types of balloons work better than others.

This car was light -and low on friction- and sped some way with this nice short balloon nozzle.

Another lightweight car -with three wheels and a craft stick frame -incredibly fast.

This was an great workshop of testing and improvement. Well done kids.