CCITE

Creating fruitful and sustainable links between

innovative organisations committed to the improvement

of technological education for young people.

The Centre for Innovation in Technological Education in Cambridge http://ccite.org

Founder: Emeritus Professor Adrian Oldknow MA, MTech, CEng, CITP, CMath, CSci, FBCS, FBIS, FIMA, FRSA, MIET

Bloodhound “Race to the line” rocket car competition exemplifying iSTEM+, KIKS and SDA approaches

Park House School, Newbury, March 2017 Adrian Oldknow adrian@ccite.org The Bloodhound Super-Sonic Car project is building a car designed to reach a speed in excess of 1000 miles per hour. It received Government support on the condition that it would be a UK focus for STEM education inspiring future scientists, engineers and technologists. Last year its Education Programme included a very successful schools’ challenge called “Race for the line” in which secondary schools built model rocket-powered cars and competed for a national award. The competition has been extended this year to include primary schools as well. Park House School in Newbury is an 11-19 Academy which has been pioneering the iSTEM+ approach to integrated STEM education and skills and is a member of the Erasmus+ `Kids Inspiring Kids in STEM KIKS’ project. It is one of the 120 regional race Hubs for this year’s competition which took place on Monday March 20th. Twelve Year 10 students (14-15 year olds) built their own cars in groups of four students. Five of these students are Student Digital Ambassadors SDAs taking part in the KIKS project. They planned and led a one-day workshop for twelve Year 5 students from the nearby Falkland Primary School to design and build their own model rocket cars, again working in groups of four. The basic kit costs £7.50 and consists of a pre-drilled block of expanded polystyrene with wheels, axles and guides. The large hole at the back is for an Estes chemical rocket which powers the vehicle for the race. The slot at the base is for a BBC micro:bit which is used to transmit acceleration data over BlueTooth. The primary day on 10th March started with a presentation from Keira about how drag slows vehicles down. This was brought to life by my fellow STEM Ambassador, Ray Buckland, who had installed a `Wind Tunnel’ app on his IPad. The SDAs had prepared cut-outs of different vehicles which the Falkland students had to put in increasing order of drag. The first session was in Mr. Marshman’s Computing classroom. The groups were able to explore websites with a variety of aerodynamic car designs. They then worked on ideas for the profile of their own car which they drew life-size on paper. The photo on the right shows Keira working with one of the groups. The template shows the area in red which must be included in the final design. The group cut out their design and taped it on to the block ready for cutting out.

When this had been completed the whole group moved to a Design Technology workshop equipped with suitable tools. Oscar is using a hot-wire cutter to shape one of the blocks to its profile. Members of each group took it in turns to smooth the surface using sandpaper. Finally the axles and wheels were attached, and the whole thing was painted and decorated. In order to test the design, Ray built a wooden catapult to ensure that each car was launched with the same thrust. Part of the kit for a Bloodhound Race Hub is a pair of light-gates mounted 1m apart, controlled by a BBC micro:bit. When the car cuts the first infra-red light beam the micro:bit starts timing. When the car cuts the second beam the micro:bit stops timing and displays the time taken in milliseconds. Which of the 3 entries do you think went the fastest?

This was a very good day for all concerned. All was now set for the actual race event ten days later.

I took along a Casio high speed camera and tripod to record the runs on video at 210 frames per second. This enabled us to introduce the free Tracker software to the SDAs for video analysis. The screen shots show the analysis of one of the runs. I have posted the edited videos here. When you open a video clip in Tracker it automatically knows the frame rate at which it was recorded – and so already has access to a `clock’ for the experiment. You can step through the clip frame by frame, and so decide which bit of use for your analysis. You can use a `measuring stick’ to provide a scale by marking a known distance, such as between the legs of the workbench behind Ray. You can also drag in axes and rotate them so that one of them points in the direction of travel. Once all is set up, you select to create a new track. This just involves performing a shift-click on the same point of interest in each frame. The results are recorded in a table and

results can be plotted. The software will also compute numerical estimates of velocity and acceleration. The results can be analysed within Tracker – the screen-shot show a linear fir being applied to the displacement data. The slope of this line approximates the mean velocity of the car. The data can also be exported for manipulation, display and modelling in other suitable software such as MS Excel or GeoGebra. For the actual regional race event, the Army sends a group to carry out the rocket launching. The cars run on a wire which passes through the two loops screwed into the underside of the chassis. The event took place on 20th March 2017. Things didn’t go quite according to plan! The weather forecast for the day showed a heavy belt of rain due to arrive around noon. So some rapid phoning around was required to ensure the teams from the three participating schools were all there in time for an earlier launch programme. While the actual runs all went according to plan, another snag arose. As well as using the micro:bit based light gates for recording times over the mid-course measured metre, each car was supposed to carry a micro:bit and battery to send acceleration data in real-time via BlueTooth for telemetry using the Bitty data-logger App. Unfortunately the code which the Army guys were using with micro:bits did not get the required communication up and running – so this part of the event had to be abandoned. The winners of the local event go on to compete in a regional event next Term, so we hope we can see this in action then.

We can see that all the entries clocked competitive times over the

measure metre ranging between and 53.6 and 64.9 milliseconds. A

time of 50 milliseconds corresponds to a speed of 20 metres per second

or 1.2 kilometres per minute or 72 kph or about 45 mph! Of the three

Falkland’s entries, flames was just the fastest. We can track a run from

a video clip using the free Tracker video analysis software, but the

results won’t be very accurate because of the perspective distortion.

The next video clip shows a car travelling over the measured metre – with a rather threatening sky behind!

It was a pity about the weather, but, in spite of it, there were still some pretty smiley faces to be seen!

Fortunately the press were on

hand too, and the event was

covered by the Newbury Weekly

News. It also appears on the

school’s FaceBook page and on

the Bloodhound SSC page on its

new stem@parkhouse website.

The previous year was the first

time the `Race for the line’

challenge took place. The

Newbury news covered the event

that year which was held at the

The Kennet School in Thatcham.

Its video gallery has a great video

of a two-abreast launch:

“Project Bloodhound at Kennet

School

Project Bloodhound seeks to

inspire children about science,

technology, engineering and

mathematics. It uses a 1000 mph

world land speed record attempt

as a foundation and pupils have

to build and test the fastest

rocket powered car they can.”

So I will finish this piece with a Tracker analysis of the first few frames of the side-by-side launch: