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Old 05-04-2015, 04:46 PM
mike howie mike howie is offline
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Default Jolly Logic Two Holes

I am thinking of getting a Jolly Logic Two Altimeter. But I don't want to put all these holes in my rockets. Has anyone 'hid' the vent holes? Like drilling the vent in the launch lugs? Or are there other ways of making the vents less visible?
Thanks.
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Old 05-04-2015, 05:00 PM
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tbzep tbzep is online now
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Quote:
Originally Posted by mike howie
I am thinking of getting a Jolly Logic Two Altimeter. But I don't want to put all these holes in my rockets. Has anyone 'hid' the vent holes? Like drilling the vent in the launch lugs? Or are there other ways of making the vents less visible?
Thanks.

Years ago when Adept and others came out with barometric altimeters, they said you had to drill your hole on a normal straight portion of the BT, uncovered. Drilling it on a taper such as the NC or covering it with what amounts to a backwards hood scoop would cause increased or decreased pressure compared to ambient air and skew your readings. I don't know if doing it inside the launch lug would have a similar affect. I have never tested it, but I would assume the various companies have.

A simple way to semi-hide your vent hole is to locate it on a painted black area, then touch up the edge of the hole to keep the brown BT from showing. Don't use a Sharpie for the touch-up. It has a sort of pearlescent affect to it when placed next to both flat and gloss black paints. Paint the inside of the tube opposite of the hole with a little black paint if the BT has a small diameter. You will be surprised just how hard it is to see the hole until you get within a couple arm lengths from the rocket. Experiment with some scrap tubing and see whether you get better results with your brand of gloss or flat black.
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Old 05-04-2015, 05:30 PM
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BEC BEC is offline
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To add to this: if you want accurate results, the vent holes have to be on a smooth surface a good distance from any bumps or protrusions on the model. Inside a launch lug is not an option.

If you don't care about the barometric data from the unit (apogee altitude, ejection altitude, descent rate) but just want the accelerometer data (max/avg. Gs, motor burn time, coast time) you could do without the static ports.....

Holes in dark-painted areas is probably the best camouflage you can do and still have the device give you good data.
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