Thermo-electrical Helicopter with siren

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Brice Lawrence Lawson
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1 :11:22 Uhr Thermo-electrical Helicopter with siren by Horst Wagner Please Note The OPITEC range of projects is not primarily intended as toys for young children. It is for teaching, designing and making to ensure that pupils experience a range of tools and processes. 1

2 :11:22 Uhr Foreward It is fascinating to see, how when you light a small candle in the model helicopter, within a few minutes the blades begin to turn and a siren sounds. This and other projects can demonstrated by constructing what is called a Seebeck device (Thermo-element) in which one side of the element is heated and the other cooled. Normally these are known as Peltier elements. They are made of small ceramic pieces with crystal blocks from Wismut and Tellur. The Peltier element system is used for a different purpose as is described in this project. Using the Peltier system direct current is sent through the connection wires ( eg 8 volt 3 Ampere) and then something remarkable happens. One side heats up to 60 degrees and the other cools to 5 degrees. You now have the principle of a heat exchanger similar to a camping cool box or a system which can be used to cool other machines. In our project we do not want to use the Peltier system in this way, on the contrary we do not want to apply electricity we want to extract it. So we are going to the opposite By heating one side of the element and cooling the other it will deliver 1-3 volts at Ma depending on the temperature difference. To produce this electricity we do not need turn a dynamo as on a bicycle, our system makes no noise and is a little bit like using solar cells. We are simply changing temperature difference into environmentally friendly produced electricity. Why is this system not well known or used commercially to produce power? There are many technical reasons why this system is not used commercially. One is that todays Thermo-elements are only 5% efficient and are expensive to produce. To achieve a better relationship experimental work is being undertaken to produce cheaper and more efficient Thermo-elements. Once this has been achieved they will have wider applications, for example, the temperature difference by burning waste and the normal outside temperature could be used as an economical way of producing power. Our project will, we hope, give you insight into this environmental way of producing power. Explanation of the terms used: We have used three different terms for the same thing, a Peltierelement is the same as a Thermo-element or a Seebeck element. The 3 terms however, describe different possibilties for their use. Peltierelement system: Here electricity is delivered to the element so that it works as a heat exchanger which can be used for cooling purposes. Seebeck sytem eg Thermo-element: In this system the temperature difference in the creamic plates is used to make a generator. 2

3 :11:22 Uhr Making the Seebeck - element system as developed by T J Seebeck (1821) Constantine wire Direction of current Solder point 1 warm Direction of current Solder point 2 cold Copper wire Measuring meter Schematic diagram layout of the Seebeck effect Thomas Johann Seebeck experimented in 1821 with joining different types of metal wire to form a circuit. As one soldering point was heated up and the other was cooling he noted that a current flowed in the closed circuit. However if both of the solder points were heated at the time nothing happened. These were the first thermo - electrical experiments and are named after the inventor and known as the Seebeck effect All thermo-generators since have been based on developments of this idea of using different materials How we can use the Seebeck element in modern technology and why? Instead of using two different metals a semi conductor material can be used, such as so called p and n doped Wisnu Tellurit which has a higher working temperature than normal metals. First experiments in the 1950s made use of this system and even today it is the most effective way of using materials to produce a temperature difference for generating electricity (and for cooling) a maximum of 5% temperature difference can be changed to electricity Todays Thermo generator systems are used in special situations The satellite Galileo is so far away from the sun that solar cells can produce little power. Here atomic energy produces the warmth which is cooled by the cold outside atmosphere. Also little known is that for many years all pipelines have used the system of thermo-generators to produce the power for their monitoring points. Here gas or oil out of the pipe is lit and the flame cooled with the air. Since 1999 a watch has been developed which uses thin film technology to produce a thermo element to power it, whereby the temperature difference between the body heat and the surrounding air make up the small thermo element to produce the power. Latest experiments in the development of thermo-elements will soon able to use thermo-voltaic and Photo-voltaic systems together, to produce environmentally free power Schematic diagram of the Seebeck Thermoelement with n and p doped Bi 2 Te 3 crystals: n doped Bi 2 Te Warmed ceramic plate (eg 100 degrees centigrade) Copper plate p doped Bi 2 Te 3 Metal plate at room temperature Seebeck voltage tapped here Looking at this diagram it might be confusing to see the two joining points, that were first envisaged by Seebeck Solution: When the two metal plates are joined, at room temperature, to make up the circuit, they act in same way as the solder joints. 3

4 :11:23 Uhr In most of the normal Seebeck elements (Peltierelements) all these basic principles are used one after the other (thermal, parallel, electrical serial) The systematic diagram of a thermo element made up from a variety of basic building blocks Thermal, parallel, electrical in series p n p n p n Thermo-voltage Warm side - ceramic Copper bands Cold side - ceramic The working effect of Seebecks experiment shown as hydro power generating station 1. Situation: no height difference 120,0 No height difference Generator does Water is still not produce power Water holder 1 Water holder 2 As both the water holders have no fall between them, the water cannot flow to move the generator. The same happens with the Seebeck effect ( Seebeck Generator) if there is no temperature difference. 2. Situation: A height difference between the water holders Water holder 1 Generator produces electricity Water flows Height 40,0 difference Here the system is easy to see working as the water flows down through the Generator So in short-no fall-no water flow and therefore no electricity is generated Water holder 2 If you use the same principle to temperature fall then you can see how the thermo-generator functions 4

5 :11:23 Uhr Warm side Cold side When a temperature difference is apparent the electricity flows through the connecting wires Thermo-element as supplied How does a Thermo-electrical driven helicopter work? If you have read through the notes on the previous pages it should not be too difficult to understand how the helicopter works. The Thermo-element in this model is activated by being heated with a tea light candle. One side of the element is heated to approximately 110 degrees centigrade whilst the other is cooled, this produces 2 volts at 100mA, enough to run both motors. The Thermo-element can only generate electricity as long as a temperature difference exists. The length of time the model will run, is however, limited by certain technical restraints. When the aluminium cooling tube has warmed up the temperature difference in the element will decrease, causing the rotor to slow and the siren become quieter. At this point, after about 10 minutes running, the candle must be blown out and the aluminium tube heat sink left to cool. The Thermo-element in this model can only take up to 140 degrees centigrade before the internal solder joints melt. There are high temperature elements available but they would be too expensive for this model. However, the working time can be lengthened by packing the heat sink tube with wet cotton wool. The water helping to absorb the heat. Using this method an extra 5 minutes running time can be gained, after which a pause must be made for the model to cool down On no account should another heat source ( eg. A cigarette lighter ) be used, as this will damage the Thermoelement beyond repair 5

6 :11:23 Uhr 1. Product information: Article: Functional model in project pack format Use: In Design Technology, Key stage 4 2. Material information: 2.1. Material: Aluminium ( Non ferrous metal )) Working: Joining: Finish: Can be sawn and filed. Gluing ( 2 part component epoxy) No special finish is necessary Material: Welding rod ( Copper coated steel) Tough, good conductor Working: Joining: Finish: Steel can be sawn, filed and formed. interlocking, soldering No special finish is necessary Material: Copper, non ferrous metal. Easy to shape, good heat and electrical conductor. Working: Joining: Finish: Can be sawn, filed and bent. Slotting together, gluing, ( Acrylic glue, 2 component glue) No special finish is necessary Material: Brass ( alloy made from copper and zinc) Hard, brittle, good conductor. Working: Joining: Finish: Can be sawn and filed. Soft soldering. No special finish is necessary. 6

7 :11:23 Uhr 3. Tools: Saws: Filing: Gluing: Soldering: Cutting metal: Use a Hacksaw for straight cuts. Note! The blade should be inserted with the teeth facing forward. The saw will only cut on the forward stroke. Be careful of sawn edges on metal they are sharp, remove the burr with a file. Use the correct grade of file according to the work in hand. Slots and notches can be made with a needle file. Note! Files will only cut on the forward stroke Use 2 component epoxy glue Do not apply the glue too thickly. Read the instructions on the packet before use! For soldering use a 60 Watt iron. Clean up the area to be soldered before starting and use a flux. Note! The hot tip of a soldering can cause burns, the iron should always be replaced in its stand after use! Use end cutters for trimming the welding rod Note! These will leave sharp edges which can cause cuts! Remove any burr straight away by filing! 4. Parts List: Part Material Amount Size Diagram Flight cell / Rotor / Skis Welding rod Metal (copper plated) 7 2dia x 500 mm 1 Brass tube 1 ø 3/0,5 x 100 mm 2 Motor pulley Brass 2 3 Cooler / holder Copper sheet 1 0,8 x 80 x 150 mm or 0,6 x 80 x 150 mm 4 Aluminium tube 1 ø 25/1 x 200 mm 5 Drive Thermo-element Various 1 5 x 30 x 30 mm 6 Motor 2 25mm dia. 7 Buzzer Siren V 8 Insulated wire mm 9 Tea light candle

8 :11:23 Uhr 5. Exploded diagram 1g 3 1h 7 1g 5a 4b 1f 4a 5a 3 7 1a 6 2a 1e 2a 1a 1 1d 1c b 4c 1i 1k 8 1i 1k 9 8

9 :11:23 Uhr 6. Planing Overview 6.1 Designing and making the fuselage sides 6.2 Making the flight cell 6.3 Designing and making the skids 6.4 Making the front and rear rotors 6.5 Making the candle holder, cooler and man rotor holder 6.6 Final assembly 6.7 Wiring and testing Important notes: - The Peltier-element is made from ceramic plates and is therefore breakable. ( Should the element be damaged, it can be repaired by bridging the broken crystals with solder ) - Before joining the copper sheet and welding rod, clean up the areas to be joined with steel wool, or emery cloth to ensure that the surfaces are grease free and clean. Also use a solderering flux. - We recommend using a multi-core electronic solder with an integrated flux core. This Thermo generator is not designed to run constantly. It should be stopped and left to cool every fifteen minutes. Constant running can damage the Thermo-element. - Do not touch the heat sink (aluminium tube and copper sheet ) this will be hot! - Beware of fire, light the candle carefully! - Remove all combustible materials from around the area of the model! - Be aware that the turning rotor blades can cause damage to the eyes of small children! - Do not let very young children near the model when is working! 6.1. Designing and making the fuselage sides For the sides of the helicopter you will need 2 welding rods (1) 500 mm long. Remove any burr with a file Bend the two rods (1) according to the plan on page 21 To make sure that the curves are smooth, place a piece of tubing or bar in a vice to bend the rod around. Check the shape continually against the pattern. Try not to use pliers for bending, as these can leave unsightly marks. Also make sure that the finished sides will lay flat on the plan. R 25,0 305,0 280,0 R 31,5 10,0 R 46,0 103,0 15,0 19,9 13,0 68,0 74,0 R 26,5 9

10 :11:23 Uhr To join the tail end of the helicopter sides (1/1a) a 15mm long (2a) a piece of brass tube (2) is needed. Make sure that the ends of the tube are free of burr so that the rod slides in easily inside. This is easier with a fine bladed hacksaw, work with care! Make sure that the brass tube (2a) is centrally placed over the join and solder it in position. To make this easier measure 7mm in from the end of the side frame and make a mark. Slide the tube up to this mark and solder it in position, this should leave 7 mm for the tail frame (1a) Trim off any extra rod at the tail end (1a) and solder the ends together to complete the side frame. 1 7,0 1a 2a Trim so that the tail parts meet Solder the tail together 6.2. Making the flight cell Take new length of welding rod (1) and use the remainders that you already have, to make the cross members (1b/1c/1d/1e) as shown in the diagram (see page 21 for patterns) 55,0 45,0 30,0 20,0 1b 1c 1d 1e Draw a copy of the plan (see page21) on a heat resistant material base (minimum 150 x 200mm) This base must be heat resistant because the cross members will be a placed on it and soldered to the side frames. 100,0 Ø 25,0 45,0 55,0 50,0 10

11 :11:23 Uhr Place the aluminium tube (5) in position on the pattern, holding it with a piece of sellotape so that it cannot tip Arrange the side frames of the helicopter on the base board so that the rear end of the frames have a gap of 12mm This gap is important as the drive motor for the rear rotor will be soldered here at a later stage. 12, Insert the cross members (1b/1c) between the side frames as shown so that they make a good contact. Solder them in position. Due to slight differences in length and angles each helicopter model will be slightly different! Once the cross members have been soldered in position and the solder has cooled, the complete helicopter can be turned over and the remaining two cross members soldered in position (1d/1e). 1c 1e 1b 1d finished cell 11

12 :11:24 Uhr 6.3. Designing and Making the skids Mark out and saw 4 pieces of welding rod (1), 2 each 130mm long (1i) and 2 pieces each 110mm long (1k). File the ends to remove any burr Bend the lengths (1i=130mm) as shown in the diagram (pattern on page 19) If possible bend two pieces together in a vice at the same time i 115,0 70,0 1k Bend the lengths (1k=110mm) as shown in the diagram (pattern on page 19) Solder the ends of each pair of skids (1i) together as shown. To solder the ends together, tape the skids together on a flat heat resistant surface. Solder here Once the parts of the skids have been soldered together solder the cross members (1k) in position. These must be at right angles to the skids and parallel. The cross members are set at 90mm and 25mm respectively from the ends of the skids. Use the aluminium tube to ensure the cross members are upright whilst they are soldered in position.! See diagram. 5 1k 90 72, , ,5 12

13 :11:24 Uhr Tape the completed skid assembly to the base board and solder the frame of the helicopter in place. Heat up the area to be soldered first and then introduce the solder!! 6.4. Making the main and rear rotor To make the main rotor mark out and saw 2 pieces 320mm long (1g) and one piece, 25mm long (1h) from the welding rod (1) and clean up the ends to remove any burr Mark the middle of parts (1g) and bend as shown ( patterns on page19) R 3,0 157,0 9,5 59,0 R 2,0 6,0 1g 2,0 4,0 1f Bend parts (1g/1h) according to the pattern and solder them together as shown. 1g 10,7 10 1h 1g For the rear rotor cut a length of welding rod as shown (1f) 100mm long. Clean up the ends and bend to shape ( pattern on page 19 ) Bend one end to the left and the other to the right! 1f 13

14 :11:24 Uhr 6.5. Making the candle holder, heat exchanger/cooler and main rotor holder Mark out and cut the copper sheet (4) (patterns on page 19) the parts (4a/4b/4c) as shown. Use a fine toothed saw or tin snips, remember to file the edges to remove sharp pieces of burr. The burr should be removed before the copper sheet is folded! 100,0 55,0 4c 51,0 4b 4a 65,0 15,0 55,0 80, Saw 2 lengths (5a) each 80mm long, from the aluminium tube (5), remove any burr Fold the copper sheet (4b) as shown 4b 30, Mark out the tabs as shown on the candle holder (4c) and make the cuts so that the tabs can be folded. 5,0 Ø 39,0 4c 14

15 :11:25 Uhr Now glue ( 2 component ) the aluminium tubes (5a) and the motor holder (4b)centrally on the copper sheet (4a) hold the tubes in place with sellotape until the glue has set. Firstly, roughen the areas to be glued with emery cloth! Read the instructions on the glue before applying it. Mix up enough glue for fixing the siren at the same time. 4a 5a 4b 5a Glue the siren (buzzer 8) to the underneath of the tea light holder. The cable from the siren exits on the narrow side of the holder. 4c schmale Seite zeigt nach hinten After the glue has set, shorten the black cable from the siren to 40mm, remove the insulation and tin the ends. Now mix the 2 component glue to fit the Thermo-element Insert the candle holder and siren into the frame of the helicopter so that the narrow part faces the rear and the cable also faces the back The front end of the candle holder should be level with the front cross member of the skids. (see diagram) Apply glue here 15

16 :11:25 Uhr To avoid the overheating and possibly destroying the Thermo-element ensure that a drop of glue is applied to each corner of the ceramic plates, so that they are glued together. Apply glue to one side of the Thermo-element which does not have wires coming out and stick it to the middle of heat exchanger (4b). The glue must applied thinly! The thinner the layer the better as there needs to be as much conductivity as possible between the two surfaces. When gluing the Thermo-element down, use a circular movement and apply gentle pressure to ensure the glue spreads evenly. Any glue which seeps out under the sides does not need to be removed. Ceramic plate with the cables is uppermost! 6 Glue the corners of the ceramic plates 6.6. Final assembly The heat exchanger and Thermo-element should be mounted about 40mm from the candle holder and fixed to the frame of the helicopter. To do this place an object about 40mm high (spare aluminium tube) on the candle holder, lay the heat exchanger/cooler on the top. The top runners of the frame should pass inside motor holder. Mark the tops of the runners with pencil inside the motor holder and remove the heat exchanger. Now bend the motor holder on these lines left and right so that a gap of 25mm remains for the motor. Finally bend the holder so that it passes around the motor. Top markings 25,0 bend here ca. 40,0 41,6 Object with 40mm height Bend the holder around the motor so that it fits snugly Shorten the black cable on the Thermo-element to 40mm, remove the insulation from the ends and tin the ends. Now replace the heat exchanger back into the frame of the helicopter ensuring that it fits squarely. When you are happy adjust it so that the Themo-element is centrally placed over the flame of the candle. Finally the motor holder can be soldered to the helicopter frame. 16

17 :11:26 Uhr Remove any packing from both the motors (7) and place a drive pulley on each shaft (3) To mount the drive pulley lay the pulley on a table top and press the motor down! Place one motor between the tail supports and adjust it so that the cables (seen from the front) pass down the along the tail support arm. Mark where the motor fits the tail structure. Remove the motor and clean up the contact points where it meets the frame with emery cloth The second motor is placed in its holder and adjusted so that the cable protrudes from the rear (as seen from the front of the helicopter) Mark the contact points where the outside meets the holder, remove motor again. Clean up these contact points with emery cloth Shorten the motor leads to 30mm, remove the insulation and tin the ends with solder. Apply flux to the contact points on the motors and the tops of the pulleys. Tin the top of the pulleys and solder the motors back in position, either in the holder or in the tail frame. Be careful not to overheat the motor casing when applying solder Tin the middle section of the rotor blades with solder. 3 cable solder points solder points Lay the helicopter flat and solder the rear rotor blade to the top of the motor pulley. Tin here 17

18 :11:26 Uhr Place the helicopter on its skids and solder the main rotor to the motor pulley Wiring and testing Solder the black cable from the motors (7), siren / buzzer (8) and the Thermo-element to one of the top metal runners on the helicopter frame Cut a 80mm long strip from the black cable, remove the insulation from the ends and then tin them. Isolate the joints with sellotape. The next stage is to guide the red cables from the siren (8) and Thermo-element (6) and the main rotor motor towards the tail rotor and solder them all together. Finally join the red cable from the rear rotor motor to the other red cables. Tape all the wiring together along the tail frame so that it looks neat. Insulate the solder joints black cable red cable red cable cable red cable black cable red cable black cable Final test: Light the tea light candle and leave it to burn for about a minute, so that the wick is fully alight Important! Remember to pay attention to the safety rules on page 9 regarding the working model 18

19 :11:26 Uhr Bending pattern: Main and rear rotor Skids, and cross members Heat exchanger, candle and main rotor holder Scale 1 : 1 4c 1g 4b 4a 1h 1i 1x 1g 19

20 :11:27 Uhr 20

21 :11:27 Uhr Layour plan: Scale 1 : 1 55,0 Bending pattern: Fuselage side Front Scale 1 : 1 50,0 100,0 1a 45,0 1 21

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