Altimeter Switches

Discussion in 'High Power Rocketry (HPR)' started by Theory, Oct 8, 2019.

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  1. Oct 8, 2019 #31

    FMarvinS

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  2. Oct 8, 2019 #32

    OverTheTop

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    I have done up to six on one pin.
     
  3. Oct 8, 2019 #33

    crossfire

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    I am done with switches. A few weeks ago I had my AMW Fibermax all ready and on the pad. Switch would not work. Took it back to my car clipped wires off switch. Twisted wires together altimeter fired right up. So back to the pad I went all went well. Twist and go has always worked for me and has never failed me.
     
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  4. Oct 8, 2019 #34

    cerving

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    It took 33 posts for twist-and-tape to come up? :) I would have figured about five...
     
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  5. Oct 8, 2019 #35

    mpitfield

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    Lol, I think that is a new record.
     
  6. Oct 9, 2019 #36

    heada

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    Well, the original poster said in post #1 that they didn't want twist and tape so do you count it as post 33 or as post 1?
     
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  7. Oct 9, 2019 #37

    Cameron Anderson

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    I'm a new convert to Wi-Fi switches. I'm a fan.
    My only request would be to have a multi-device-capable switch...one switch, one phone interface, but the ability to control a primary and back-up altimeter (or even a 3rd device as well). I ran an RRC2 and Marsa33 off one Wi-Fi switch by powering the switch with two 7.4v 600mah lipos in parallel. I needed to control both altimeters in the interstate coupler of my Nike 5.5" booster and there wasn't room for two separate switches so I made due.
     
  8. Oct 9, 2019 #38

    Theory

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    He did say that didn’t he...
     
  9. Oct 9, 2019 #39

    Hybrid33

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    it requires a tool to arm/disarm or you set a switch inside the e-bay and need something pokey to operate them. Solved that Problem this year At LDRS
    IMG_1251.JPG
     
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  10. Oct 9, 2019 #40

    cerving

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    Well, us old guys have a hard time remembering threads this long... :)
     
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  11. Oct 9, 2019 #41

    cerving

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    Running multiple devices from one switch is certainly possible, all you have to do is to connect the power for the devices together. If you're thinking redundancy (uh oh, THAT thread again...) you need one switch per device, and one battery or set of batteries per device. No single points of failure...
     
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  12. Oct 9, 2019 #42

    Steve Shannon

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    Whatever commercial switch you use, just make sure that it is rated for G-forces. Most are not.
    I’ve found slide switches and micro switches that are. I’ve never seen a keyswitch rated. They’re built for security, not reliability. I don’t like them for the same reason Fred cited for pull-pin switches, but even worse.
    The screw switches probably are not mainstream manufactured so I wouldn’t expect G-force ratings.
     
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  13. Oct 9, 2019 #43

    mpitfield

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    Anecdotally, I can tell you that the Featherweight Mag switch and the FingerTech micro screw switch will survive flights in excess of 50Gs.
     
  14. Oct 9, 2019 #44

    FredA

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    "G" rating is over rated.
    You don't really need "G" rating.
    You need a switch that won't open by itself.
    I use a very-non-G-rated switch, but with a few dabs of epoxy it becomes bulletproof.
     
  15. Oct 9, 2019 #45

    watheyak

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    This is/was a Fingertech switch. Probably more than 50 Gs and it still works!

    There was no need for a tool to disarm this one...
     

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  16. Oct 9, 2019 #46

    tOD

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    I'm building a redundant bay and was asking myself this question. Now I see I don't have true redundancy without two switches. Guess I'll order aWiFi switch for the Quark that's the backup for the Quantum.
     
  17. Oct 9, 2019 #47

    Steve Shannon

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    I didn’t say it clearly enough. What I meant was that I would consider using the screw switches even though they come without a G-rating.
     
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  18. Oct 9, 2019 #48

    Theory

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    Thank you all.

    I am thinking that I will either use the Missile works PCB switch that I have used in the past and simply work on my building skills OR go with the Finger Tech Robotics switches. I like the idea of working a solution to have a them arm / disarm without tools from the switchband, however, that may lead to other challenges.

    As for carrying a tool around, no worries there.

    Hope to officially kick this build off soon
     
  19. Oct 9, 2019 #49

    Cameron Anderson

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    I would like one Wi-Fi switch with multiple inputs and outputs just for ease, not necessarily redundancy, so I don't mind having 1 device control the power for 3 others. The Wi-Fi switch doesn't have the smallest footprint so three control options in one switch would be nice. I redundancy is my charges, that's about it. Modern electronics, properly set and wired, don't fail. I have yet to see an altimeter just not work...there is always some user error in set up or wiring.
     
  20. Oct 9, 2019 #50

    DAllen

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    Naaahhhhh...This is nothing compared to glue threads. This more of a "this is what I prefer to do" kinda thread rather than the "OMG WHY WOULD YOU USE THAT GLUE TO GLUE THAT TO THAT" discussion haha.
     
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  21. Oct 9, 2019 #51

    ghostfather

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    upload_2019-10-9_15-43-10.png
    I prefer to use "insert before flight" switches, inserting the metal plug from a banana plug (tapped to accept a threaded insertion tool, or long bolt).
    The plug has to be inserted to turn it on.
    Using the "remove before flight" sort I've had failures during high G launches where the flimsy contacts would separate and reset the altimeter.
    Now I use almost exclusively magnetic switches, and once forgot to drill air holes for the barometric altimeter.
    With a plug, I always had a big enough hole. Only made that mistake once.
     
  22. Oct 9, 2019 #52

    Buckeye

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    Back to post #1. What is wrong with using two of the switches that you like and work well?
     
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  23. Oct 9, 2019 #53

    Chris_H

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    This switch survived a ballistic burial and an AV bay fire from the LiPo's. Switch still works. The other side looks better. It is in good enough shape that it has also survived numerous attempts at putting it in the trash.

    I have not had any real need for wireless switches, but I leave that option open just for 'extreme problem solving'. I would have difficulty trusting them fully.

    [​IMG]
     
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  24. Oct 9, 2019 #54

    Theory

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    Nothing really other than I anticipate challenges with lining up a pair of them with static ports places at perfect 90 degree intervals. As the build progresses this may prove to be a non-issue, however, as I love to over analyze every aspect of a build, I wanted to address the switches before I began purchasing pieces.
     
  25. Oct 9, 2019 #55

    Stable1

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    Can you elaborate?
     
  26. Oct 10, 2019 #56

    ghostfather

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    Using a plug, I always had a big enough port hole in the rocket to insert the plug to arm the electronics (insert before flight). This insertion port is big enough that it also serves as port for the barometric altimeter.

    Using a magnetic switch, I don't need a big port hole. One of the first time I used a magnetic switch on a new rocket, I forgot to drill a port to get air to the altimeter. The altimeter couldn't sense the outside air pressure, and therefore didn't pop the chute at apogee or at altitude. It came it ballistic.

    Luckily it wasn't anything big or expensive, and I was able to recover the chutes and altimeter for re-use. Learned from it.

    In the past I had a phase where I liked to fly the really fast burners (Vmax, for example) just to see whether the fins would stay on ;-)
    Fast burning motors create a high G force at launch.

    At the time I used a similar switch, but with "remove before flight", meaning that it closes when removing the non-metal plug/rod/pin, arming the altimeter. The contacts inside the switch are just spring metal that spring together when the pin is removed. I don't know whether the switch was worn, or the orientation of the switch to the launch direction was ideal to be affected by G forces, but at launch it momentarily lost power to the altimeter causing it to reset. The result was that the altimeter was still rebooting at apogee, but recovered, armed itself or detected a launch (don't know how) and pushed the main out at 200 meters altitude. Of course it was coming in ballistic, and shredded the main chute. Damaged the rocket beyond repair, but the electronics were fine.

    Looking at the recorded flights from the altimeter, one launch recorded about a half of second of data (on the ascent), and a second launch recorded a launch, but was able to detect altitude and pushed out the main.

    After that happened, I decided to go with "Insert Before Flight" switches (Normally Open) that others were using. Had to build a special tool to insert the pins, and had to tap the end of the pins to work with the tool. It's a bit more work, but I feel it's safer.

    That said, most folks will never have failures with "Remove Before Flight" switches. It may be a consideration for anyone doing extreme flights or high G flights to use another switch that can't spring open under G forces.
     
  27. Oct 10, 2019 #57

    FMarvinS

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    _____ ______ _______________ _______________ ______

    Steve,

    I've had no problems using pull-pin switches during high G flights. If you decide to retry them then, as Steve Shannon suggests-purchase ones with G ratings. Also, many of mine are set horizontally on the AV bay sled so that gravitational forces are perpendicular to the plane of the movement of the switch arm.

    Fred
     
  28. Oct 10, 2019 #58

    dvdsnyd

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    Fred, Would you be able to provide a visual on this setup, including the disconnect and shut capability?
    Thanks,
    Dave
     
  29. Oct 10, 2019 #59

    FMarvinS

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  30. Oct 10, 2019 #60

    FMarvinS

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    David,

    My posts related to pull-pin switches and if that is what you are referring to, I can send a few photos within a few days. Please let me know if the following descriptions are related to your question. I am currently building an AV bay for the Wildman Drago 4XL (great kit!) and I can send you pictures, although the bay is not near completion, of the horizontal encasement position for 4 switches utilizing one rod. A second picture will show the "guts" of a single switch in its 3D printed enclosure with the rod (which is a bicycle spoke) securely in place by being screwed into the attached spoke nipple.

    Fred
     

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