Recent content by NyeSpy

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    Need recommendation for rheostat or potentiometer

    I wired the two 7.2v NiCd in series and tried the lift fan again. This is an illegal configuration (over 9v), but that fan is an impressive bit of technology. Its too bad we cannot use it. :)
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    Need recommendation for rheostat or potentiometer

    As to target mass, we want to get as close to 2 kg as possible without going over. A 2 kg craft that hits the targeted time will score maximum points.
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    Need recommendation for rheostat or potentiometer

    A ton of great suggestions and questions here. As to the skirt, we are hoping to be able to fabricate one that has an open bottom which will minimize friction. If we cannot pull that off, we will try a closed skirt with lots of tiny holes (think air hockey table top). The push fan we...
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    Need recommendation for rheostat or potentiometer

    Just realized the issue with the lift fan and it will indeed need to be exchanged. 9v is below the minimum range for that particular fan. Found another that generates 1019 pascals static pressure that will operate with voltage as low as 5.5v. The students aren't the only ones learning! :)
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    Need recommendation for rheostat or potentiometer

    So it is impossible to operate a 12v fan with less voltage? Wouldn't it just run slower? Other teams seem to be successfully using 12v cooling fans. Confused. Fortunately it can go back if necessary.
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    Need recommendation for rheostat or potentiometer

    Just discovered the 8.4v NiMh on Amazon. :) I'm thinking that could make a huge difference. Worth a shot???
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    Need recommendation for rheostat or potentiometer

    We unboxed the fans today and started planning the build. The push fan is working marvelously, but the lift fan is definitely going to need more power than my 7.2v NiCd battery can provide. We even tried wiring both batteries together in parallel and the fan still will not spool up. It...
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    Need recommendation for rheostat or potentiometer

    This is indeed for Science Olympiad. We are not sure how well the rheostat idea is going to work. If we are unable to achieve consistent, reproducible results with the rheostat we will scrap that idea and go with the mechanical restriction of airflow. It is all about experimentation and...
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    Need recommendation for rheostat or potentiometer

    I cut and pasted from the original rule set which included the bit about brushless motors. In September, they released the following - "Hovercraft 4.i. should read: "Brushless motors and integrated circuits are not permitted, unless they are an integral part of and are imbedded into a...
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    Need recommendation for rheostat or potentiometer

    Brushless computer fans are OK also. Sorry for all the confusion... I could have posted all of the rules and regulations, but wanted to shorten my post by two pages. :)
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    Need recommendation for rheostat or potentiometer

    The lift fan can get full power. It will be on a separate battery and we won't need to adjust the voltage for that. It is the "push" fan that needs to be adjustable. We expect that most contestants will vary the amount of thrust by mechanically varying to flow of air to/from the push fan. We...
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    Need recommendation for rheostat or potentiometer

    Thanks for all of the input! I think I may go with that 6" bar rheostat. We'll have plenty of space on board the craft. I did hear back from the event coordinators regarding the transistorized PWM. They stated that there could potentially be issues with any design involving transistors or...
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    Need recommendation for rheostat or potentiometer

    I did. My head is still swimming. :) Is that something I can buy or will it need to be built? Still waiting for the judges to weigh in. I would be shocked if something this complicated would be allowed. The rules seem to indicate safety and SIMPLICITY. Here's a few more rheostats I...
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    Need recommendation for rheostat or potentiometer

    Yikes, $50 is definitely hard to swallow (considering I've already dropped $65 on fans). If it matters, the longest run time will be 25 seconds. Does that allow us to downsize any to a less expensive part?
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    Need recommendation for rheostat or potentiometer

    I am seeking a clarification on the rules. I am pretty sure they are going to say this is not allowed. Until I hear back, what do I need to be looking for in a rheostat or potentiometer? We want to have as much control over fan speed as possible (a lot of variation) without too much fear of...
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