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Thread: Key Ignition vs. Toggle Switches

  1. #31
    Senior Member jrevens's Avatar
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    Default Re: Key Ignition vs. Toggle Switches

    Quote Originally Posted by SS7Flyer View Post
    You can run a very simple on-off-start ignition switch when using toggles for the ignition boxes.
    You can run an even simpler momentary contact on-off keyed switch for the start function, along with the ignition switches. That happens to be how they do it in the RV-12s, and that's what I did too. In fact I used the same compact, light weight switch that the RV uses too... pretty much like what is used on many alarm systems. The 2 ignition toggle switches are completely separate from that start switch. Which ever you use, you want to be sure to use an arc-suppressing diode on the start solenoid/contactor coil circuit to protect the contacts in the start switch from a possible large back emf pulse created when the coil is de-energized and the magnetic field collapses.
    John Evens
    Arvada, CO
    Kitfox SS7 N27JE
    EAA Lifetime
    Chap. 43 honorary Lifetime

  2. #32
    Senior Member Flybyjim's Avatar
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    Default Re: Key Ignition vs. Toggle Switches

    I am building the ss7 but have not yet ordered the firewall forward kit, is this not all included with this kit?. I would like to think Kitfox has these answers all worked out with this kit. The last kit I built, not a Kitfox had all the parts supplied with the two toggle switches and a start key switch.

  3. #33
    Senior Member jrevens's Avatar
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    Default Re: Key Ignition vs. Toggle Switches

    Quote Originally Posted by Flybyjim View Post
    I am building the ss7 but have not yet ordered the firewall forward kit, is this not all included with this kit?. I would like to think Kitfox has these answers all worked out with this kit. The last kit I built, not a Kitfox had all the parts supplied with the two toggle switches and a start key switch.

    My kit came with a standard ignition/start key switch made by ACS - a copy of the original Bendix switches. Some of us prefer to have separate switches for ignition and start, rather than the combo switch. There are people who claim to have had ignition module failures that they attribute to the combination switches, including at least one well-known Rotax supplier. This has been discussed on this forum in the past, Jim. There are some other advantages to having separate switches also.
    John Evens
    Arvada, CO
    Kitfox SS7 N27JE
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  4. #34
    Senior Member GWright6970's Avatar
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    Default Re: Key Ignition vs. Toggle Switches

    John,
    I purchased Bob Nuckolls' 12th Edition from him. It REALLY helped me with a lot of things, but I needed a diagram better than his Rotax 912 Figure Z-16; with Notes 2 and 3 not helping much to clarify things. I have no idea what that box is that the ignition module wires go to...I have a guess, but I hate guessing!

    I have been blessed by two builders who have allowed me to photograph their flying aircraft. In one of these aircraft the ACS OFF R L BOTH START switch is also installed with two toggle switches. On the other side of the panel, the ACS switch is clearly wired to the R and L contact points with wires appearing to be coming from the two toggle switches next to it. I am guessing that the toggle switches are installed in series between the ACS switch and the ignition modules. I do NOT see shielded wires... Much less the shielding being grounded. This got my curiosity really going to say the least....hence my original question.

    I have read and understand both sides of the ACS switch debate. I also have listened to discussions on the benefit of turning over the engine without the modules "on." I wish to therefore use BOTH the toggle switches and the ACS switch. I do have the ACS diode to install on the starter solenoid.

    (So I also gather that the shields are to protect the modules from electromagnetic compatibility and electromagnetic interference that can be introduced by the brown ignition wires.)

    SUMMARY
    From what I now gather from my Rotax 912 Installation Manual and your reply, I can run a shielded wire from each module to it's toggle switch, connecting the shields as described.... The ACS would then be wired as shown in the Kitfox manual except that the two "brown ignition" wires are attached to the toggle switches instead of the ACS switch. I will also install the diode.

    Thank you!!!
    Grover Wright
    Flying a KF IV-1200
    ROTAX 912UL

  5. #35
    Senior Member jrevens's Avatar
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    Default Re: Key Ignition vs. Toggle Switches

    You're welcome, Grover. Just one additional comment - I probably wasn't clear enough, but shielding is probably not needed on the ignition wiring for these Rotax engines. Again, the shielded cable is a little more robust and perhaps less vulnerable to serious damage than un-shielded cable. It's nice to be able to use the shield for the ground path on those particular circuits is all, and additionally you have shielding whether needed or not... (just in case?). FWIW, I wouldn't be a fan of using extra switches in series with the combination switch contacts. You're just introducing another potential failure point in the circuit, with no advantage at all that I can see. You would have 4 sets of contacts that have to be made instead of just 2, in order to make sure your engine is "safe" from accidental ignition. Simpler is better in this instance, IMHO. It sounds like you're not going to do that, and I believe that is what you are saying in your summary... that you will use the ACS switch, but just not use the ignition switching feature of it, only using it as a start switch. Is that correct?
    Last edited by jrevens; 12-02-2017 at 11:11 PM.
    John Evens
    Arvada, CO
    Kitfox SS7 N27JE
    EAA Lifetime
    Chap. 43 honorary Lifetime

  6. #36
    Senior Member GWright6970's Avatar
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    Default Re: Key Ignition vs. Toggle Switches

    (?... that you will use the ACS switch, but just not use the ignition switching feature of it, only using it as a start switch. Is that correct?)

    John,
    You are correct. I will NOT be running the module brown wires on to the ACS switch. I will run the module wires to the toggle switches ONLY.

    I will be using the shielded wire and grounding both ends... Even though I read an EAA Sport article that said to ground only one end.

    Again, thank you!
    Grover Wright
    Flying a KF IV-1200
    ROTAX 912UL

  7. #37
    Senior Member jrevens's Avatar
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    Default Re: Key Ignition vs. Toggle Switches

    Quote Originally Posted by GWright6970 View Post
    (?... that you will use the ACS switch, but just not use the ignition switching feature of it, only using it as a start switch. Is that correct?)

    John,
    You are correct. I will NOT be running the module brown wires on to the ACS switch. I will run the module wires to the toggle switches ONLY.

    I will be using the shielded wire and grounding both ends... Even though I read an EAA Sport article that said to ground only one end.

    Again, thank you!
    OK, that's good... except- you DON'T ground both ends. The engine end is the only connection to ground. The other end goes to the switch.
    John Evens
    Arvada, CO
    Kitfox SS7 N27JE
    EAA Lifetime
    Chap. 43 honorary Lifetime

  8. #38
    Senior Member GWright6970's Avatar
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    Default Re: Key Ignition vs. Toggle Switches

    John,
    Ok... I have a shielded wire. I place a molex connector on one end on the internal wire conductor and slide that pin into the molex 6 pin connector.

    I take the other end of this shielded wire, and place a terminal on the internal wire conductor, and then this end is connected to a toggle switch leg.

    I then install a pigtail from the shield on the end near the module and land that on a ground near the modules. The shield on the toggle end gets a pigtail attached and the pigtail is grounded to the switch housing.
    (That takes care of the wires between the toggle switches and modules.)

    I take a different wire, place a terminal end on each end; and connect one end to the other toggle switch leg, and the other end goes to the ground connection.

    Does this work?
    Grover Wright
    Flying a KF IV-1200
    ROTAX 912UL

  9. #39
    Senior Member GWright6970's Avatar
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    Default Re: Key Ignition vs. Toggle Switches

    Only a few more wires to go!

    Thank you everyone!! Huge thanks to you John!
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    Last edited by GWright6970; 12-03-2017 at 12:02 AM.
    Grover Wright
    Flying a KF IV-1200
    ROTAX 912UL

  10. #40
    Senior Member jrevens's Avatar
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    Default Re: Key Ignition vs. Toggle Switches

    Quote Originally Posted by GWright6970 View Post
    John,
    Ok... I have a shielded wire. I place a molex connector on one end on the internal wire conductor and slide that pin into the molex 6 pin connector.

    I take the other end of this shielded wire, and place a terminal on the internal wire conductor, and then this end is connected to a toggle switch leg.

    I then install a pigtail from the shield on the end near the module and land that on a ground near the modules. The shield on the toggle end gets a pigtail attached and the pigtail is grounded to the switch housing.
    (That takes care of the wires between the toggle switches and modules.)

    I take a different wire, place a terminal end on each end; and connect one end to the other toggle switch leg, and the other end goes to the ground connection.

    Does this work?
    Sorry... no. It works, but not as I described.
    OK, here we go... you have two ignition modules and they will both be wired the same way, individually, with 2 separate, shielded single conductor cables. To do it as I described (as per Bob Nuckolls) you are not going to ground anything at the panel on these circuits. You use the shields as a conductor to ground at the engine, not specifically just as a shield grounded at the engine, as you describe. The center conductor goes to the ignition module on one end, and to a switch terminal on the other end. The shield goes to the ground at the engine (like you said) and the other end of it goes to the common terminal on the switch (with a pigtail also). There is no additional wire going to a switch terminal, and again, no grounding at the panel or “switch housing” on these particular circuits. Then of course, the switch needs to open the circuit when it is “on”, and close the circuit when it is “off”. I guess you could say the object of doing it this way is to ground the module remotely at the engine, with a switch at the panel. You could do the same thing with a simple 2 conductor cable, but this way uses the shield as one of the conductors, so that it does “double duty” by acting as a shield, grounded at only one end (the engine), when the switch is “open”.
    John Evens
    Arvada, CO
    Kitfox SS7 N27JE
    EAA Lifetime
    Chap. 43 honorary Lifetime

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