Hoop Gliders

I came across these hoop gliders several years ago, but I revisited them with my children when we were participating in the Tech Challenge 2016, Taking Flight. And just like the Birds of PLAY, we made these gliders to prototype (we thought using the gliders in the shape of birds would be fun at the competition) and understand the mechanics of flight.

Before you start, throw a plain straw. Does it fly well? Not really. It’s because the straw doesn’t have wings. It has nothing to generate lift. But when you add hoops, they act as wings, generating lift. And depending on where you put the hoops, your hoop glider will generate more lift or less. You experiment with sizes and locations of the hoops and decide what works best for your hoop glider. 

 This is what we're making today. 

These are quite simple to make, and they are incredibly fun to throw and watch them fly. This is a great project you can do with your children/students inexpensively. I hope you try this project and have a lot of fun.

List of Supplies:

·                     Straws (different lengths and diameters)

·                     Paper strips (copy paper, construction paper, cardstock, etc., whatever you have handy)

·                     Scissors

·                     Adhesive tape

Cut the paper in 1/2" or 3/4" strips. You can experiment with other widths, but these are the widths that seemed to work best. I also have three different sizes of straws. For my convenience, I made my hoop gliders with the wider, pearl drink straws. But I had students make hoop gliders with regular straws, and they did well with the smaller diameters, too. So, it really doesn't matter too much. Again, if you have different sizes available, experiment.

These paper strips are 3/4" wide. I like this width for no other reason than that it's the width of scotch tape. So, that's the width I use, but I've seen other project instructions online with 1/2" width instructions. Tape the ends of the strips together and make circles. You can experiment with lengths, but I tend to use 3", 6", 9" and 12" strips. I don't know why. I think it's the proportions that matter, not the actual lengths.

You can put as many or as few hoops as you want. But the minimum number is 2.

Have fun with where you put the hoops. Go crazy and fail spectacularly!

As you see, the left hoop gliders hoops are not aligned. The hoop in the back is attached in the middle, but the hoop in the front is attached to the right handside. Play with where you attach the hoops - in the middle, left side, right side, etc.

Just want to show you the different sizes of the hoops I attached. Again, the goal of these projects is to have fun.

I made 4 hoop gliders this morning. but when I conducted this project in class, some students have made as many as 10+ gliders. So, make a lot and have fun.

How to throw a hoop glider. Gently throw it forward.

 

This one flew pretty straight and far.

This one flew the farthest, almost toward the fence & the rose bushes.

This one was interesting to look at slow-mo, because the largest loop would swing back and forth between left and right. But it didn't fly far.

This one was all over the place, but interesting to watch.

It's a perfect day to fly gliders! Have fun!

Balloon Rocket Cars

I am always looking for an easy project I can do in a classroom of 30+ kids. If I can quickly put kits together, that's great, but many projects, especially when preparing for 30+ kits, take a lot of work and time. So, when I found a kit for this project for $1.20/kit, I jumped on it and bought 4 sets of 10 kits. But I realized that I could probably put a kit together cheaply with every day materials.

Putting the vehicle together took matter of minutes, which was great since I only had an hour for the project. Then they were asked to power it by attaching a balloon to it. They were given a choice of two different sized balloons as well as complete freedom to shape and attach the straws whichever way the students wanted to try. I like to tweak things a bit, forcing the students to figure things out on their own.

The students had a fantastic time trying out different weights, sizes, attachments and learned while having fun. Unfortunately, we didn't have enough time to try out the incline surfaces and frictional losses. But, I'm looking to continuing with it during next school year.

I hope you’ll have fun with this project!

SUPPLIES:

For Vehicle:

• 1 Corrugated plastic or cardboard piece for the vehicle body (3 in x 5 in)
• 2 Plastic coffee stirrers
• 1 Plastic drinking straw, cut in two equal pieces
• 4 Foam disks for the wheels (~ 2.5 in in diameter and 0.5 in thick), but if you can't find these, you can cut them out from the same corrugated cardboard
• Tape

For Rocket Balloon Power:

• 1 Plastic drinking straw
• 1 Balloon any size, but I took balloons of various sizes to the classroom to show the students the difference in air-power (also, to show them that BIGGER isn't always BETTER)

INSTRUCTIONS:

• I used a delivery cardboard box to cut out my vehicle chassis (3 inches x 5 inches).

I was able to cut out several fairly easily and quickly. But I'm not sure I'd be up for cutting out 30+ sets x up to 12 classrooms. So, I would probably buy the kits, if I could still find them for $1.20/kit.

• Cut a drinking straw in half.

If you have a bendy straw, cut off the bendy part first. Then cut the rest of the straw into two equal pieces.

• Tape the cut pieces of straw on to the both narrow sides of the vehicle chassis, centering it across the width.

• Insert one end of the coffee stirrer into one of the foam disks.

• Insert the coffee stirrer with a wheel attached already through the already taped drinking straw on the vehicle chassis.
• Insert another wheel on the remaining end of the coffee stirrer.

• Do the same for the other side.

• Cut a drinking straw to your desired length.

If you have a bendy straw, you can decide what to do with the bendy part. Then cut the straw to the length you want. It's up to you to decide which length works for your design.

• Insert a straw into a balloon.
• Put a rubber band around the neck of the balloon over the straw.

DO NOT tie the rubber band too tight. It can collapse the straw, and it won't work well (I've learned from experience).

I decided to create two different designs to see if there's a difference in the distance the vehicle traveled.

• The 1st balloon rocket design has a straight straw piece inserted in the balloon.
• The 2nd balloon rocket design has a bendy straw piece inserted in the balloon.

The 1st balloon rocket design traveled farther with the vehicle than the 2nd.

NOTE: I tried 2nd balloon rocket design with the bendy part up and down, and both positions had problems. Why don't you try it and see what it does?

PROBLEM SOLVING:

• As soon as the students started testing their balloon rocket cars, they complained about the wheels coming off completely or their cars curving to the right or the left. I challenged them to come up with a solution to their problem.

Many started with taping the ends of their axel to stop the wheels from coming off, but it didn't stop the wheels from wobbling and not going straight (which was one of the requirements of the project).

• Some complained that their vehicles refused to move, even with a gigantic balloon attached to it.

They had taped the axel (the coffee stirrer) to the axel housing (cut drinking straw), and it couldn't rotate. Therefore, the wheels couldn't rotate, which prevented the vehicles from moving.

• Some students did blow gigantic balloons and learned that BIGGER isn't always BETTER.

Though the vehicles started fast, but they turned upside-down or rolled to one side due to the balloon rocket being too powerful for the vehicle. We tried to weigh down the vehicle, but it didn't work very well.

ADDITIONAL PROJECT IDEA 1:

This is part 1 of the add-on project I didn't get to do with the class.

• Measure how far a vehicle will travel on flat surface.

• Ramp 1 - Measure how far the same vehicle will travel on this inclined surface.

The plastic tub is 6 inches high, and the ramp is 22 inches long.

• Ramp 2 - Measure how far the same vehicle will travel on this inclined surface.

The plastic tub stack (2 tubs) are 12 inches high, and the ramp is 22 inches long. The steeper descent made the vehicle more unstable, and it crashed into the nearby wall.

ADDITIONAL PROJECT IDEA 2:

This is part 2 of the add-on project I didn't get to do with the class.

• Measure how far a vehicle with travel on flat surface (see project idea 1).

• Measure how far the same vehicle will travel on carpet.

NOTE: The car on the carpet will not travel as far as the car on the smooth surface. The difference in the distance traveled is the force lost due to friction.

SCIENCE BEHIND THIS PROJECT:

I love Newton's Second Law, because it's easy for people to understand.

Force = Mass x Acceleration.

I use this all the time when I do projects with students. Whether it's a kindergarten class or a sixth-grade class, I write F = ma on the whiteboard and explain the relationship between them.

On flat surface (1st diagram): F = ma = F (Balloon) - F (Ground friction)

• The total of all the forces acting on our vehicle will result in acceleration.
• How fast the vehicle will accelerate will depend on the size of the force acting on the vehicle.
• When the air in the balloon is pushed out of the straw through the back, the balloon is pushed forward. When the balloon is pushed forward and is taped to the vehicle, the vehicle moves forward with the balloon.

Actually, F=ma is too simple. What it really means is that F = ma = F (Balloon) - F (Ground friction). But in most cases, we assume F (Ground friction/Resistance) = 0 on smooth surfaces because it's very, very small.

On a ramp (2nd diagram): F = ma = [F(Normal) - F(GravityY)] + [F(Balloon) + F(GravityX) - F(Ground friction)]

• The total of all the forces acting on our vehicle will result in acceleration.
• How fast the vehicle will accelerate will depend on the size of the force acting on the vehicle.
• When the air in the balloon is pushed out of the straw through the back, the balloon is pushed forward. When the balloon is pushed forward and is taped to the vehicle, the vehicle moves forward with the balloon.

If the ramp is smooth, F (Ground friction) = 0, too. F (Ground friction) depends the smoothness of the surfaces, not the angle of inclination. And conveniently, [F(Normal) - F(GravityY)] = 0, because they are equal and opposite forces.

So, the long equation is shortened to F = ma = [F(Balloon) + F(GravityX)].

NOTE 1:

In kindergarten, I use addition/subtraction to get them to understand the relationship between the three. If F is constant, and m is big, a is little and vice versa.

NOTE 2:

If you want to solve for F(GravityX), the mathematical equation is

F(GravityX) = F(Gravity) x sine(angle).

If you want to solve for F(GravityY), the mathematical equation is

F(GravityY) = F(Gravity) x cosine(angle).

NOTE 3:

In More Air-Powered 2, Frictional Forces, F(Ground Friction) is not 0.

The car on the carpet will not travel as far as the car on the smooth surface.

The difference in the distance traveled is the force lost due to friction.

Bridge Building Series - Truss Bridge 2

Truss Bridge 2 – Straws & tape (A challenge project)

This project needs more accurate taping, which might be a tad difficult for primary students. However, I've done this project with a group of 3rd graders, and they were able to build sufficient truss bridges.

Supplies:

·         A bag/box of straws

·         Tape

·         Scissors

·         Small cups

·         Paper clips

·         Weights – pennies, paper clips, etc. Anything is OK as long as they weigh the same. You want to compare how much different bridge designs can support

    

Instructions:

1.      Cut a bundle of straws to same size (~2 1/2 inches long). Leave some for different lengths. These will be cut to size.

2.      Tape four pieces together to make a square. Tape uniformly across all places. Create enough square to span an opening that is 10 inches wide.

Created bottom of the truss bridge first, then continued to build the sides of the bridge. (These squares measure to 11 inches in length.)

3.      After creating several squares, put cross bracings diagonally (cut these to size).

4.      Put the top pieces last and enclose the truss bridge.

5.      Place the truss bridge between two desks, tables, chairs, etc.

6.      Hang a small cup in the middle of the bridge (use hole puncher and paper clips) and load it with pennies, paper clips, etc. to weigh it down and test its strength.

Same amount as beam bridge

Added more coins

Added another bucket full of coins.

7.      Different size straws, too much tape on one side vs. the other side, etc. will create imbalance and weaknesses in the bridge structure. Try to balance taping, straw usage, etc. on all sides.

This straw and tape truss bridge was much stronger than I expected. I think I could have added another bucket of coins, but I ran out of bridge space. Maybe you can build a longer bridge and test how many buckets of coins your bridge will hold. Of course, the longer the bridge span, weaker the bridge. So, you might have to consider the bridge span vs. support strength of the abutment.

Remember, Engineering is all about failing and trying, again. So, try and try, again.