Attaching ventilation eyelets for altimeter

Discussion in 'Rocketry Electronics and Software' started by MetricRocketeer, Apr 14, 2019.

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  1. Apr 14, 2019 #1

    MetricRocketeer

    MetricRocketeer

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    Hi everyone,

    A few days ago I received my new Jolly Logic AltimeterThree (JLAT). Just to begin experimenting, I plan to use the JLAT on some low-power rockets that I have -- namely, an Estes Drifter and an Estes Firestorm.

    I understand that, for ventilation purposes, I need to make at least three of four holes in the airframe evenly spaced around, and that each hole should have a diameter of approximately 2.0 to 3.5 mm.

    Making the holes should not present a problem using a standard drill. As I further understand it, the holes themselves are sufficient to provide ventilation. To strengthen the holes, however, and to make them more attractive, I should attach eyelets.

    Here's the problem. The holes need to start a bit more than 25 mm aft of the front end of the airframe. To get the underside of the eyelets to spread out, the instructions say to use either a Dritz #104T tool or a 574 pliers kit. But these devices will only reach in about 25 mm -- not deep enough into the airframe for me use the tools.

    Does anyone have any advice, please?

    Thank you.

    Stanley
     
  2. Apr 14, 2019 #2

    Rex R

    Rex R

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    use a small drop of ca on the edges of each hole, let them harden, then redrill sand if needed to remove the fuzzies.
    Rex
     
  3. Apr 14, 2019 #3

    MetricRocketeer

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    Hi Rex,

    Thank you for your reply.

    I want to make sure I understand what you are saying. You suggest forgetting about the eyelets altogether, right? Just use glue.

    And when you say CA -- I am always a little unclear on this -- that could mean wood glue. Is that correct?

    Stanley
     
  4. Apr 14, 2019 #4

    Titan II

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  5. Apr 14, 2019 #5

    MetricRocketeer

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    Hi Titan II,

    OK. Thanks. And very useful link.

    Stanley
     
  6. Apr 14, 2019 #6

    Rex R

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    correct, the thin super glue seeps into the tube and hardens the region around the hole(also the fuzzy fibers) letting you clean up the holes and eliminate the eyelets.
    Rex
     
  7. Apr 15, 2019 #7

    MetricRocketeer

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    Thank you Rex and Titan II for your very useful contributions. I am glad to know that I can proceed on this without having to use the eyelets.

    Actually, while I am on the subject, I would like to be able to use the eyelets. And if I could get the device deeper into the airframe, I would do so. Since I cannot, however, then using the thin super glue will be just fine.

    Thanks again.

    Stanley
     
  8. Apr 15, 2019 #8

    Rex R

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    there is a reason (or two) for the eyelet suggestion(and a downside). when one drills a paper tube it can leave 'stuff' in the hole which can collect paint from painting and mostly block the hole and cause problems for the altimeter, the eyelets prevent the holes from being blocked (by fuzzles), downside the eyelets may disturb the airflow over the holes and cause improper alt readings during the time the rocket is going fast. provided one has cleaned up the vents and has nice smooth unblocked holes, there is little reason to use eyelets...unless maybe one wants a sort of steampunk look :).
    Rex
     
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  9. Apr 15, 2019 #9

    MetricRocketeer

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    Not to misunderstand, I am all set on not using eyelets. It will actually make my work easier.

    But just to pursue this matter to the ultimate degree, I remember seeing a discussion as to whether the airflow over eyelet holes would or would not lead to improper altimeter readings.

    What do people think about this issue? If you could use eyelets, could they actually lead to incorrect altimeter readings?

    Thank you.

    Stanley
     
  10. Apr 15, 2019 #10

    dhbarr

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    This would be a fairly easy experiment to set up, actually.

    One rocket, several 'levels' of individual compartments, each with varying numbers and sizes of holes with / without grommets etc.
     
  11. Apr 15, 2019 #11

    John Beans

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    I have made rockets that use eyelets (just press them in a hole with some glue, no need for crimping tool), and they do look quite cool and can be added after painting. They do disturb the airflow at high speed, and you need to be aware of what the back side looks like, and whether it will snag anything on the inside.

    Best: vent holes that are crisp and flush with fuselage ("drill, superglue, sand, repeat" method prior to painting)
    Next best: any hole at all, including with eyelets that may distort pressure at high speed
    Worst: no holes
     
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  12. Apr 15, 2019 #12

    Curtis Enlow

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    Cosmetically, I love the look of an recessed, aircraft-style static port with a polished aluminum disc flush to the skin (which would eliminate the Bernoulli effect), but short of using a press and tooling to obtain the conforming radius I'm not certain how one could fabricate it...?

    [​IMG]
     
  13. Apr 15, 2019 #13

    John Beans

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    Try inkjetting on a metallic silver weatherproof label. Carefully cut a precision hole in the middle of it. That should mask any rough edges of the actual hole beneath it, and let you put labeling to look like a static port panel. And a label is thin and won't distort the airflow much at all.
     
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  14. Apr 15, 2019 #14

    Curtis Enlow

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    Ooooo, that's a great idea! One could also sandwich a circle of metal tape and drill holes, which should keep them nice & clean, and apply the tape to the tube with appropriate markings. That would look pretty cool...
     

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