Introduction to rockets and model rocketry 3 2

Introduction to rockets and model rocketry 3…… 2…… 1……Blastoff

This session with cover… • • Uses of rockets Principles behind rockets What is a model rocket Motors Construction tips/why do we need to sand ? Kits verses scratch build Sourcing materials Video examples UKSEDS Rocketry Training Day 2013, Sheffield University 2

Uses … Military – Blowing stuff up…No…no…no not allowed here. • Space – Yes…yes dreams are made of this, however not possible for us …YET. • Scientific Research – Science is awesome. Why would we not propel awesome to Mach 5. • Hobby/Entertainment – Who would not be entertained ? • UKSEDS Rocketry Training Day 2013, Sheffield University 3

Principles of rocket • An object at rest or in constant motion will stay at rest or in motion unless acted upon by a force • F = ma • Every action has an opposite and equal reaction A resultant force must be exerted on a rocket for it to lift off from a launch pad (first law). The amount of thrust produced by a rocket engine will be determined by the mass of rocket fuel burnt and how fast the gas escapes the rocket (second law). The reaction, or motion, of the rocket is equal to and in the opposite direction of the action, or thrust, from the engine (third law). UKSEDS Rocketry Training Day 2013, Sheffield University 4

What is a model rocket http: //www. youtube. com/watch? v=86 t. Ts. Pi 0 FPc UKSEDS Rocketry Training Day 2013, Sheffield University 5

Parts Fins • Fins are crucial to a rocket as they provide a restoring force when a rocket moves off course, therefore keeping it stable and flying straight up. • This is done by providing a moment around the CG which counteracts the moment from the aerodynamic forces which act at the CP • Fins can be bought from rocket website however geometries are limited. • Buying balsa sheets then cutting them out is the best way to make custom fins. • You will need a fin template (http: //www. robhouse. co. uk/rocksim/ ) to cut accurately around you. Training want all to be. University identical 6 UKSEDS and Rocketry Dayyour 2013, fins Sheffield

Parts Fins • Alignment – it is important your fins are all aligned and at the right distance from each other. • For scratching building I recommend making a alignment guide e. g. rolling paper round your body tube, printing one out etc • Also when your fins are glued on it is recommended to add fin fillets, this again increase strength, aerodynamics and aesthetics UKSEDS Rocketry Training Day 2013, Sheffield University 7

Parts Motor mount • Motor mount hold your motor in place • Centering and engine block are the most crucial parts • Motors mount can be made removable, therefore interchangeable • Cluster motors can be made canted • Centerings are best bought with their corresponding body tube. However it is possible to make your own • Model rockets come with an engine hook to stop the motor falling out and in high powered rocketry a retention system is used instead UKSEDS Rocketry Training Day 2013, Sheffield University 8

Parts Shock cord • These attach your parachute and nose cone to the body plus absorb a lot of the energy when the nose pops off a avoid the nose cone or parachute detaching from the rocket. • For model rockets this is normally Kevlar cord attached to an elastic cord. • Pretty easy to get from a shop. • Make sure you attach them properly and glue all knots so they cannot come undone. UKSEDS Rocketry Training Day 2013, Sheffield University 9

Parts Glue • Your model rocket is solely held together by this magical substance • Most material in model rocketry are paper based or wood so craft glue and wood glue are sufficient • However always use as directed, allowing for proper gluing time, so do not rush. • Be careful with application, too much glue adds weight and makes a rocket messy • Use the right glue at the right time. Super glue sometime is not that super UKSEDS Rocketry Training Day 2013, Sheffield University 10

Parts Parachute • This amazing device returns your hard work back to earth in a relatively safe manor, the alternative is not desirable. • Size depends on weight and descent rate but 12 -15 inches in diameter should do. • When attaching your parachute ensure the strings are not tangled and attachments are strong. • Always use wadding when launching, to avoid your parachute being burnt UKSEDS Rocketry Training Day 2013, Sheffield University 11

Parts Launch lug • Crucial item, this is what connects your rocket to the launch pad • Do not forget it which a lot of people do. If you are using a D motor your launch lug should be a 5 mm(1/4”) launch lug and below can use 3 mm(1/8)” launch lugs. UKSEDS Rocketry Training Day 2013, Sheffield University 12

Parts • Any magical parts of a model or high powered rocket that have mystified you before ? UKSEDS Rocketry Training Day 2013, Sheffield University 13

Motors http: //www. estesrockets. com/media//catalogs/Estes_2013_Catalog 2. pdf UKSEDS Rocketry Training Day 2013, Sheffield University 14

UKSEDS Rocketry Training Day 2013, Sheffield University 15

Motors • Class Total Impulse • I 320. 01 -640 N·s Total Impulse (Metric Standard) (Imperial Standard) • A 1. 26 -2. 50 N·s 0. 29 -0. 56 lbf·s • B 2. 51 -5. 0 N·s 0. 57 -1. 12 lbf·s • C 5. 01 -10 N·s • D 10. 01 -20 N·s 2. 25 -4. 48 lbf·s • E 20. 01 -40 N·s 4. 49 -8. 96 lbf·s • F 40. 01 -80 N·s 8. 97 -17. 92 lbf·s • G 80. 01 -160 N·s 17. 93 -35. 96 lbf·s • H 160. 01 -320 N·s 1. 13 -2. 24 lbf·s 35. 97 -71. 92 71. 93 -143. 83 lbf·s • J 640. 01 -1280 N·s 143. 84 -287. 65 lbf·s • K 1, 280. 01 -2, 560 N·s 287. 66 -575. 3 lbf·s • L 2, 560. 01 -5, 120 N·s 575. 31 -1150. 6 lbf·s • M 5, 120. 01 -10, 240 N·s 1150. 61 -2301. 2 lbf·s • N 10, 240. 01 -20, 480 N·s 2301. 21 -4602. 4 lbf·s • O 20, 480. 01 -40, 960 N·s 4602. 41 -9204. 8 lbf·s UKSEDS Rocketry Training Day 2013, Sheffield University 16

Types… • Sports rockets – Just for fun • Cluster rockets – Two or more engines at once • Multistage – Two or more rockets used one after the other in • flight High performance/ Competition UKSEDS Rocketry Training Day 2013, Sheffield University 17

Types… • Cluster - Rockets that have more than one motor burning simultaneously. • The benefit of this is having smaller, cheaper and more easier to develop thrusters, which can the provide a larger take off thrust of a bigger engine. Clustering is suitable for when you need more thrust at liftoff to launch larger or heavier rockets. • This total liftoff thrust/impulse is equal to the sum of the thrust/impulse of your constituent motors, • Example: If you used two engines in cluster this would be equivalent to a motor that is twice as powerful but burns just as long. UKSEDS Rocketry Training Day 2013, Sheffield University 18

Types… • Example: Two B 6 in cluster vs Single C 6 • So this would produce the same power as a C 6 but in half the time therefore this would actually be equivalent to a C 12 engine which does not exist. Which add a level of versatility. Consequently you could also lift double the maximum weight of a B 6 or C 6 with this configuration. UKSEDS Rocketry Training Day 2013, Sheffield University 19

Types… • Important things when designing a cluster rockets is building you rocket strong to handle this extra power as you can effectively get the thrust of a high-powered engine with the right configuration. • Also how you design your motor mount to hold all these engines. http: //www. rocketshoppe. com/info/Engine_Clusters. pdf • It is important that the thrust must be evenly balanced around the centerline of the rocket. If there is more thrust on one side your rocket will veer off course and become unstable. Additionally making the engines as close to the centerline as possible, therefore if one motor fails the rocket will not loop dangerously near the ground. • https: //www. youtube. com/watch? v=-Zzp. PY 4 g. Mk. Q UKSEDS Rocketry Training Day 2013, Sheffield University 20

Types… • Cluster UKSEDS Rocketry Training Day 2013, Sheffield University 21

Types… • Multistage – Rockets that use more than one engine which in succession. • The benefit of this is to achieve a high altitude because each stage is jettison so the last stage is very light and can coast for a long time. • There are two ways to stage a rocket, direct and indirect staging. • Direct staging is used for black powered motors, the lower stage engines ignites the upper stage. This is relatively simple process and design once you understand how the staging works and ensure your rocket is stable http: //www. apogeerockets. com/Tech/How_2 -Stage_Rockets_Work UKSEDS Rocketry Training Day 2013, Sheffield University 22

Types… • Composite motors (High powered motors) require indirect staging, where there is a device onboard the rocket that will ignite the upper stage at a chosen time. This is because composite motor ignite from the top of the stack and not the bottom like a black powered motor. • Therefore additional electronics are required on board, this will consist generally consist of a timer and battery, these can fortunately be bought, then if you are feeling brave you could design one yourself. • What starts the timer ? Typically two simple methods are used, pull pin and g-switch. • Pull pin is simpler and cheaper however g-switch is safer and more reliable. UKSEDS Rocketry Training Day 2013, Sheffield University 23

Types… • However there altimeters that can also do this, plus flight computer packages which can fire the rocket only once if meets certain requirement (tilt) for added redundancies and safety. • I recommend someone adventurous or decent at programming could make an Arduino or Raspberry Pie based system which could do this. • http: //youtu. be/PLS 8 s. FNJOz 4? t=2 m 40 s UKSEDS Rocketry Training Day 2013, Sheffield University 24

Types… • Performance/Competition rockets- Rockets that are designed to a specific high performance target. • Most commonly these are optimized for speed or altitude, also more speed does not necessarily mean more altitude so there are different aspects to optimise for both • These rockets normally take careful consideration when being designed and built to perform to their best to achieve a target. UKSEDS Rocketry Training Day 2013, Sheffield University 25

What else do you need…. • • Launch Pad (this guides you rocket) Launch controller Building equipment e. g. sand paper, glues, hobby knives etc Location, ideally a rocketry club UKSEDS Rocketry Training Day 2013, Sheffield University 26

Construction Tips • I cannot go through the whole of how to construct a rocket in such a short time, but apogee rockets, an American rocket supplier has a You. Tube channel with many videos on construction. • http: //www. youtube. com/user/apogeerockets • http: //www. youtube. com/watch? v=5 w 0 LJ 7 Hw 72 w UKSEDS Rocketry Training Day 2013, Sheffield University 27

Construction Tips Sand till you have no fingers • Drag of a rocket is a big factor which will affect the performance of any rocket. • Drag compromises of two components, skin friction drag and pressure drag. Pressure drag is to do with how air moves around the rocket. • Skin friction drag comes from the boundary layer which is attached to the rockets surface, so a smoother rocket means less skin friction • Also it makes your rocket look better UKSEDS Rocketry Training Day 2013, Sheffield University 28

Construction Tips Sand till you have no fingers • Sanding should be done in stages using a coarse grit progressively using finer grits. • A good range of grits to use are 240, 360, 600, 1200. However this will depend on the material you sand. UKSEDS Rocketry Training Day 2013, Sheffield University 29

Construction Tips Before applying glue • Model rockets are held together by glue. So insuring the best possible strength of you bonds it crucial. • So one glue might not be best for everything, this will depend on what your are gluing to what. • Before gluing it is recommended to lightly sand the contact areas, this reveals clean untouched material plus give materials a larger surface area. • The grater the surface are for a given area the stronger your bond will be. UKSEDS Rocketry Training Day 2013, Sheffield University 30

Construction Tips Built in Fins • Mainly for Mid/High powered rockets fins are built in. • What this means is that the fins actually go through the body tube, this increases the strength of the bond to the body tube. UKSEDS Rocketry Training Day 2013, Sheffield University 31

Construction Tips Fin fillets • These are used to increase the strength of your fins • They also provide better aerodynamic behavior at the root edge of your fins. • Normally made from glue or putty which is then sanded or covered by filler then sanded UKSEDS Rocketry Training Day 2013, Sheffield University 32

Construction Tips Finish • You are not finished till you have a finish • Finishing your rocket again is not just for making it look nice but if you do it right, your rocket will be smooth the sail through the air. • Before finishing sand your rocket thoroughly by using filler and sanding it down repeatedly. • Once this is done choose a colour scheme and paint, glossy has a decent finish. UKSEDS Rocketry Training Day 2013, Sheffield University 33

Kits verses scratch build • A model rocket kit comes with all the parts you need to construct a certain rocket • Example: Magnum Hornet UKSEDS Rocketry Training Day 2013, Sheffield University 34

Kits verses scratch build • Scratch built rockets are designed and built from scratch, normally with an aim or some sort of design challenge. This is your starting point. • Producing a design on a rocketry CAD software helps with analyzing stability and simulation, plus visualisation. UKSEDS Rocketry Training Day 2013, Sheffield University 35

Kits verses scratch build Scratch build considerations • Is my design stable and safe • Does it meet my specification • Can I get all the materials I need • Construction • Cost • Recovery UKSEDS Rocketry Training Day 2013, Sheffield University 36

Kits verses scratch build Pros of Kits • All the parts are provided • Model have been tested and proved to work well • Normally cheaper than buying individual parts • Shorter time scale • CAD files readily available • Easiest and recommended for beginners Pros of scratch build • Design to a certain specification • Designs are only limited by your resources, so they can be as crazy as you want. • Your own creation and unique • Greater understanding of rocketry UKSEDS Rocketry Training Day 2013, Sheffield University 37

Materials Common materials. • Cardboard – Body tube • Glassine – Body tube • Quantum tubing - Body tube • Fiber glass - Fins, Body tubes, nosecones • Carbon Fiber, Body tubes, fins • Plywood, Internal structures • Plastic – Nose cones • Metal – Nose cone tip (dangerous), bolts and hooks etc • Other – Light, strong and suitable for their use UKSEDS Rocketry Training Day 2013, Sheffield University 38

Sourcing Materials • Sourcing materials can be quite problematic as places to get rocket specific items are few and far apart in the UK. • First you need to know what you want to buy, this can be from your design. It is also a good idea to split what you need into rocket specific items and items readily available: • Rocket specific • Fins (Balsa, Plywood) • Body tube ( Strengthen Cardboard) • Nose cone • Motor mount • Parachute UKSEDS Rocketry Training Day 2013, Sheffield University 39

Sourcing Materials • Readily Available items • Fins (Balsa, Plywood) • Body tube ( Strengthen Cardboard) • Shock cords/Nylon/Kevlar • Hooks Once you have that we need to go shopping. UKSEDS Rocketry Training Day 2013, Sheffield University 40

Sourcing Materials • There are two main places to go. www. rocketandthings. com www. modelrockets. co. uk • However they do have a limited amount of stock and order items from America etc only a few times a year. • So you may find you need to order from both to get al your parts or neither has them. • In this case send an email to make sure, the try finding alternative sources, there a few in Europe e. g. http: //www. rebelrocketry. com/shop/index. php UKSEDS Rocketry Training Day 2013, Sheffield University 41

Videos • • http: //www. youtube. com/watch? v=_e-sev. UOpec http: //www. youtube. com/watch? v=z 7 f. Lp. Kt 56 Jk http: //www. youtube. com/watch? v=rfn. DEry. I 3 Dk http: //www. youtube. com/watch? v=5 LL_W 2 Fd. EFA&feature= plcp UKSEDS Rocketry Training Day 2013, Sheffield University 42

Research, Links and information • Shops http: //www. modelrockets. co. uk/shop/index. php http: //www. rocketsandthings. com/ http: //www. estesrockets. com/ http: //www. rebelrocketry. com/shop/index. php • Websites http: //www. ukra. org. uk/ http: //www. apogeerockets. com/ http: //howtobuildmodelrockets. 20 m. com/index. html UKSEDS Rocketry Training Day 2013, Sheffield University 43

References • http: //web. mit. edu/16. 00/www/aec/rocket. html • http: //blog. siriusrocketry. com/2013/07/chris-michielssonsmodel-rocket. html • http: //www. stormthecastle. com/model-rockets/the-estes-hiflyer-rocket-part-2. htm • http: //blog. siriusrocketry. com/2013/07/chris-michielssonsmodel-rocket. html UKSEDS Rocketry Training Day 2013, Sheffield University 44