Making Model Gliders

KIT GLIDER

I have recently started making model gliders.  The first glider I built was a balsa wood kit bought from the local hobby shop.  The kit consists of 7 pieces.  2 wings, 1 tail plane, 1 vertical fin, and fuselage and 2 wing supports.  

Kit glider

Before assembling the kit, I had to use sandpaper to give the wings a shape like an aerofoil.  Next I used SuperGlue to attach the wing supports to the fuselage and the wings to the fuselage and wing supports.  Lastly, I attached the tail pieces.

Kit Glider wing supports

The most time consuming part was shaping the the wing profile, and the most difficult part was getting the angle of the wings the same on both side.

Kit Glider replacement fin

It flew quite well.  After a few hard landings, the tail fin broke off, and I replaced it with a plastic fin. The heavier fin meant I had to add some weight to the nose. It still flys quite well.

HOME MADE GLIDER MK1

My next model glider was a home made copy of the kit plane built from balsa wood.  I cut out all of the pieces using a craft knife.  I shaped the wings and assembled the plane as described for the kit.  This glider was a lot lighter than the kit, mainly due to the balsa fuselage.   I added sticky tape trim-tabs to the outer wings.  The glider flew really well, until it had one too many hard landings.

Mk 1 built from scratch using balsa wood

Home made Mk 1

The material I used for the fuselage a mistake, as after one or two hard landings, the fuselage broke just behind the wing.  I used a wooden kebab stick, which I split down the middle, to repair and reinforce the fuselage.  After another few hard landings, the balsa broke yet again, just behind the reinforcing.  I added another layer of reinforcing, combined with added weight on the nose.  This has resulted in a really fast glider that can handle high wind speeds.  The trim tabs help during slow flight, but are too floppy to make much difference when I throw the glider really hard.

Mk 1 Fuselage repairs

HOME MADE PIZZA TRAY GLIDER

After doing some research on the internet, I found a video by GrandDadIsAnOldMan on how to build a glider using a styrofoam plate.  The next time we had pizzas for supper I built my Mk 2 glider.  I cut the fuselage from some scrap ply wood and built the wings and tail plane from the styrofoam trays that came with the pizza bases. 

Mk 2 Plywood fuselage and polystyrene wings

Instead of using SuperGlue, this time I used a hot glue gun to assemble the model.  I got the centre of gravity wrong, so I had to add some weight to the nose.

Mk 2 nose weight.  Ply wood and hot glue

The glider was very light and after a few flights in a moderate wind, a wing broke off.  After repairingthe wing, I added a layer across the topof the wings for strength.

Mk 2 - Broken Fuselage

The next problem was the fuselage.  After a few more test flights, it broke in the same place as Mk 1, just behind the wing.  Obviously, the ply wood I had used was not very strong.  This time I used a split chopstick to reinforce the fuselage.  Then the tail fin broke off.

Mk 2 - Trim tabs

CONCLUSIONS

If you want to make a model glider, be sure to use strong wood for the fuselage, or reinforce the fuselage BEFORE it breaks.  Bamboo chopsticks work really well for reinforcing.

If you use styrofoam for the flying surfaces, you will need to reinforce that too.

Happy building!

Big Bubbles

We made big soap bubbles this week. We mixed one cup of dish washing liquid, 10 cups of water and half a cup of glycerine in a big plastic basin. the basin was quite shallow, so we did not have to make too much.

Then we took a wire coat hanger and bent into the shape of a giant magnifying glass, and wrapped string around the outside. After everything was ready, we made bubbles. The mixture lasted about a week. We just added water and a little dish washing liquid now and again. The longest bubble tubes were about 1.5m long and the biggest bubbles were over 40cm in diameter.

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A bubble has just popped behind Euan's head. You can see the bubble mist in the air.

See more bubble pictures.

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Hot Air Ballons

Today we used a plastic garbage bag, a gas cooker, a cardboard box and a hot air to make a hot air balloon. Before we started Euan fetched a bucket of water just in case anything caught fire. It was very windy outside so we had to make the ballon inside.

We opened the top and bottom of a cardboard breakfast cereal box and made it into a tube. This went over the gas burner to act as a chimney. We lit the cooker and kept the flame very small, then put the chimney over the flame, making sure it was not too near the flame.  The gas heated the air and sent it up the chimney, then sucked in cool air from the holes in the cooker.

With one person on either side of the cooker, we held the bag over the cooker and watched as it filled with hot air. When it started to tug, we let it go and it shot up to the ceiling.

We did not put weights on the bottom of the bag so it tipped over quite easily and let all of the hot air escape.  Then the bag floated gentle down to the floor.

 After a while, the bag got too hot and the plastic started to melt. Next time we will try making the bottom a little heavier, and maybe make the opening a little smaller.

All the pictures are on https://picasaweb.google.com/ReeceSwart/20110130_Hot_Air_Balloons_Part_1#.

Carbide Flames

We saw a methane experiment on TV, and we decided to check if it would work with acetylene.

First we needed to make some stuff. We needed a gas generator. We cut the centre out of the lid of a hot chocolate bottle, and glued a plastic funnel on top. Next we took some pipe the builders had left in our garden, and fitted it onto the funnel. The plastic bottle may melt, but glass bottles are too dangerous to use in case they explode.

Next we got the bubble bucket ready. We put a little water into a plastic bucket and added quite a lot of dish washing liquid. Then we put the free end of the builders pipe into the soapy water, and put a brick on top to keep the pipe under water.

The last thing we had to make was a long distance fire lighter. We tied a candle onto the end of a long stick, and lit the candle.

We put some carbide into the gas generator, added some water, and screwed the lid on quickly. Dad said this was the dangerous bit, so he did this part. the carbide in the bottle started to fizz and the gas generator got quite warm, so we put it into another bucket of water to keep cool.

Very soon, the gas started bubbling out of the end of tube under water, and made lots of bubbles. I took the burning candle and stuck it into the bubbles and woosh, we had a great big flame followed by lots of black smoke.

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We took turns lighting the bubbles until it stopped bubbling. The gas coming out of the generator was very smelly.

Vinegar cork gun

We took some bicarbonate of soda and put it into a plastic bottle.  Dad said we must use a plastic bottle because a glass bottle is very dangerous if it breaks.

When there was enough bicarbonate of soda in the bottle we added some vinegar, and quickly put a cork into the bottle.

Very soon it went pop, and the the cork shot out of the bottle.

We tried again, but did not have enough vinegar, so we mixed some lemon juice with the vinegar.  This time the mixture in the bottle made lots of bubbles, but the cork stayed in so I picked up the bottle and gave it a good shake.

Very soon the cork popped out and went flying across the garden.

Bubbles and surface tension

The other weekend, we decided to learn about surface tension.  I took a plastic plate and filled it with water, then sprinkled pepper on the surface of the water.

Once everything was still, I added a few drops of dish washing liquid and watched the pepper speeding around the surface of the water as the soap changed the surface tension.

I wanted to make patterns, so I added some food colouring to the water.  The green colour just sank to the bottom.  It was boring, so to make it fun again, I took a straw and started blowing bubbles.  That was the best part.