Recent content by BobCannon

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    Can Computational Flow Dynamics Predict the Performance of CO2 Rocket Cars?

    Hi and thanks for the pointer towards Graphalloy bearings. This could be very useful as long as we can achieve an excellent polished finish on the axles. I agree with your thinking on the balance between rotating and non-rotating mass in the car. I remain convinced that this is significant in...
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    Can Computational Flow Dynamics Predict the Performance of CO2 Rocket Cars?

    I have come across SPICE as a circuit simulation tool, but not thought of it as a tool for analysing mechanical systems. We use small shielded ball bearing races 2 mm ID 5 mm OD about 2 mm wide. These have enabled us to produce some very fast cars. I would be interested in knowing about the...
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    Can Computational Flow Dynamics Predict the Performance of CO2 Rocket Cars?

    I found this equation to calculate the frictional torque in ball bearing races (http://www.smbbearings.com/SMBtechdata.htm) Frictional torque (measured in Nmm or Newton millimetres) Radial ball bearings: 0.5 x 0.0015 x radial load in Newtons* x bearing bore (mm) The website also quotes...
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    Can Computational Flow Dynamics Predict the Performance of CO2 Rocket Cars?

    Thanks Mike In the Bloodhound SSC class the rules are very simple, the cars must be machined from a single block of balsa wood. The wall thickness around the cylinder must be a minimum of 3 mm. The body between the from and rear axles must be a minimum of 15 mm diameter and the centre height...
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    Can Computational Flow Dynamics Predict the Performance of CO2 Rocket Cars?

    Hi All Mike, When you suggest Finite Element Analysis may be more informative than CFD could you give me a bit more of an idea how you would envision using it? My knowledge of the technique is very limited. I remember using it to simulate the decent of the lunar lander on a Teachers' course...
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    Can Computational Flow Dynamics Predict the Performance of CO2 Rocket Cars?

    Hi In the UK Denford run the competition and supply the bits and pieces. See their catalogue at http://www.denford.ltd.uk/cataloguemay09/index4.html I think Pitsco supply similar in the US. See http://shop.pitsco.com/store/default.aspx?CategoryID=84&by=9&c=1&bhcp=1 The UK competition has...
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    Can Computational Flow Dynamics Predict the Performance of CO2 Rocket Cars?

    Thanks for the interest in my thread. With regard to the effect of the size of the orifice I think this is quite controlled. A standard launch device is used which drives a spring loaded firing pin into the diaphragm so that variability has been minimized. Also the CO2 cylinders are stored at...
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    Can Computational Flow Dynamics Predict the Performance of CO2 Rocket Cars?

    Hi All Hope this is the right forum, I am looking for an applied approach! I am interested in modelling the behaviour of CO2 powered rocket cars. These small models are powered by releasing pressurised carbon dioxide from a “sparklet” cylinder. The model cars race along 24 metre long...
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