G3X touch + GNX375 a minimalist EAB IFR panel? Backup "gyro"(G5) req'd? GTN650 instead of GNX375?

Discussion in 'Avionics and Upgrades' started by Narwhal, Feb 25, 2021.

  1. Narwhal

    Narwhal Pre-Flight

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    Go easy, I have no idea what I'm talking about when it comes to "technically advanced aircraft" as they relate to 91.205 and exprimental category aircraft.

    considering a "builder assist" EAB situation in the next year or so. They told me they could build an IFR panel on a tandem taildragger in a brief sales discussion, didn't hash things out in detail. I just want to expand my knowledge before furthering the discussion with the manufacturer.

    Would the 10.6" G3X touch PFD/MFD and a GNX375 (which is an IFR GPS navigator and ADS-B in/out 1090ES transponder) be sufficient for legal IFR instrumentation in an EAB aircraft (enroute nav and RNAV approaches to LPV mins)?

    I would most likely add a G5 backup instrument for safety, but would that be required by regulation? G3X alone seems to include all the instruments required by 91.205.

    This manufacturer prefers to use a separate radio tuning head, a GTR-200 for the VHF comm radio, stating that the G3X can be cumbersome to tune by itself. Panel space is at a premium.

    Would a GTN-650 be more practical than the GNX375 since it could function as the radio tuning head? I have minimal use for a VHF nav radio as included in the 650, and a seperate ADSB transponder would be required with the 650, adding cost and weight.

    Normally they just equip with a G3X and GTR200 radio tuning head, optionally a remote mount ADS-B transponder, which of course isn't IFR approved due to lack of IFR GPS navigator. No, IFR would not be my primary mission or even fall within the "90% of your mission" rule, but if IFR capability could be attained for just 2-3% additional cost and ~10lbs of weight, it seems prudent.

    Thanks for any insight.
     
    Last edited: Feb 26, 2021
  2. Cluemeister

    Cluemeister Line Up and Wait

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    I have the GNX375, G3X and backup G5. IFR experimental.
     
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  3. Narwhal

    Narwhal Pre-Flight

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    Pretty much what I want to do. Do you think it would be useful to have a GTR-200 VHF radio tuning head, or is the G3X pretty friendly to use? I have watched a few videos on the G3X and it seems pretty intuitive, but have talked to a friend that seemed very glad he had the GTR-200.
     
  4. Cluemeister

    Cluemeister Line Up and Wait

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    I have one panel mounted radio and one remote. I tune both of them from the G3x screen. The logic was in bumpy IFR I wanted to be able to touch a physical dial. Still working on my IFR ticket so not sure that was the right decision yet.
     
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  5. Cluemeister

    Cluemeister Line Up and Wait

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  6. Narwhal

    Narwhal Pre-Flight

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    Ah, so even though you have the panel mounted radio you still tune it through the G3X most of the time? That makes sense, because in Garmin's videos it didn't look to be a huge issue to tune the radios. I use a number pad to tune radios at work and have never had an issue, granted those are physical buttons which I'd expect to be significantly easier than a touchscreen in turbulence.
     
  7. Stewartb

    Stewartb Final Approach

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    The G3X Touch works great for tuning my remote radio and txp (GTR20 and GTX23ES). And working the autopilot. If you’re adding an AP for IFR I’d recommend a dedicated controller but the radios are no big deal at all. Tap on the top radio line and a half screen tuning page comes up. Same for txp. Really simple.
     
    Last edited: Feb 26, 2021
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  8. Jesse Saint

    Jesse Saint Line Up and Wait

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    The G5 is definitely not required, but it’s a cheap way to get a backup adahrs.

    I like having at least one physical radio for turbulence. Being able to tune it on the screen is also nice, although just being able to see the frequency on the screen is a big benefit.

    you can get a remote mounted transponder that has its own GPS antenna and is ADS-B compliant.
     
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  9. Stewartb

    Stewartb Final Approach

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    Today most G3X systems will incorporate a GDL50R. You’ll have backup adhrs on your phone or iPad. And that’s why I chose not to use a G5.
     
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  10. Stewartb

    Stewartb Final Approach

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    upload_2021-2-26_4-49-41.jpeg
     

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  11. Narwhal

    Narwhal Pre-Flight

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    Interesting point. I guess one would one be at the mercy of the DAR and manufacturer on whether or not they would allow they would allow IFR to be written into the airworthiness certificate of an aircraft with only a personal electronic device as an AHRS backup. Also, I presume an ipad would require a stratus/stratux etc for an AHRS source should an electrical failure render the rest of your avionics inop, granted I don't see how they'd have the regulatory standing to require it. I might try to go that route if I could though, especially for an airplane that would be flying very minimal IFR.
     
  12. Stewartb

    Stewartb Final Approach

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    If you use a GDL50R for ADS-B in you’ll already have a backup ADHRS. Talking to Garmin I was told that should the GDU screen fail the GSU info is still bluetoothing to my devices. In a perfect world the EIS info would backup via bluetooth, too, but no joy. My G3X has never had a hiccup but I do run it through a TCW BBS. Ship’s power is the likely fail point of the system.
     
  13. CA182R

    CA182R Pre-Flight

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    These guys specialize in making G3X Touch panels for Slings. https://midwestpanels.com/

    Their YouTube channel is very informative. Check out the video "GNX or GTN to equip your aircraft build for IFR?"

     
    Last edited: Feb 26, 2021
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  14. asicer

    asicer Final Approach

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    Have a look at the Trig TY91. Control head is about 2.25" wide by about 1.25" tall. It follows the SL30/SL40 protocol so it can be remote controlled by the G3x. Also has a built-in 2-place intercom.
    [​IMG]
    [​IMG]
     
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  15. Narwhal

    Narwhal Pre-Flight

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    Talking with sales today, this is the IFR panel they recommend. I will probably not want the autopilot though. It costs $7,000, about 6 or 7 lbs of extra weight, and I can only imagine the extra maintenance were it to ever break.

    The rest of the panel is an additional $20k over the VFR-only G3X, installed. I think I would be happy with it.

    G3X
    GNC355
    G5
    GTX-45R
    pitot heat

    panelc.JPG
     
  16. Salty

    Salty Final Approach

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    More than adequate for the type of ifr I’d fly in while in a tandem tail dragger. I wouldn’t fly hard IFR in that type, but if you’re going to, you probably want the AP
     
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  17. Stewartb

    Stewartb Final Approach

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    The G3X will drive a 2-axis autopilot with the addition of two $750 servos. No other added equipment is required. Garmin’s servos have a great reputation for reliability.

    Admittedly I’m biased. I’m not interested in IFR in a Cub. Do you have much Cub time?
     
    Last edited: Feb 27, 2021
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  18. Narwhal

    Narwhal Pre-Flight

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    My contact said the autopilot would be controlled by the G5. Maybe the autopilot was included in the $20k ifr package, not 100% clear as I’m still over a year away from the build. I didn’t know the G3X and G5 could do that!
     
  19. Stewartb

    Stewartb Final Approach

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    My G3X drives my 2-axis AP. If you want to add a yaw damper you need to add a controller.
     
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  20. Narwhal

    Narwhal Pre-Flight

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    I have about 5 hours of PA18 and PA14 time, so no. I did love my PA18 time so far. If they weren’t $250/hr to rent, I’d have more time. One of them had dual G5’s. This is a very ancillary aspect of the airplane and I’m half tempted to just forget it and go VFR. The problem I have is wrapping my head around having that nice big G3X and being limited to VFR, even if it’s hardly a limitation. I expect the FX3 to be a 120 knot/135 mph cruiser on 8.50’s though, so it would be a reasonable cross country machine, in theory.

    That’s the same speed as my current 182, believe it not, which is in theory ifr capable, but in practice a single VOR with no DME or GPS is pretty useless.
     
  21. Stewartb

    Stewartb Final Approach

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    Sounds like you need an RV! By next year FX-3s will be pushing $400K. A guy really needs to know what he wants at that price point. My Cub world is all about slow and short. The only reason I have 35” tires is because they don’t make 40s. Have you talked to Legend?
     
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  22. asicer

    asicer Final Approach

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    If you are counting ounces, a GNX375+Trig TY91 is a little bit lighter than a GNC355+GTX45R. The tradeoff is a couple square inches of panel space and maybe a little bit of transmit power.
     
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  23. Kenny Phillips

    Kenny Phillips En-Route

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    Chance that I'd rely on an iDevice for a secondary attitude reference whilst flying in actual = 0.
     
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  24. Stewartb

    Stewartb Final Approach

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    Fair enough. Show us what your G3X backup solution is.
     
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  25. Ravioli

    Ravioli Final Approach PoA Supporter

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    GTN650. Of course. It's the Bonanza of navigators.

    There are other more logical and practical options, but there is only one answer.
     
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  26. AlphaMike

    AlphaMike Pre-takeoff checklist

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    answer = GTN750
     
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  27. Narwhal

    Narwhal Pre-Flight

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    Well, I did decide to order the new airplane (an FX3).

    Have to decide between this for $0 extra (except I think they could put an airgizmos mount for a Garmin aera 760 or an Ipad Mini instead of the obsolete Garmin aera 796, and add $3k for a GDL-50r ADS-B in+AHRS source):

    [​IMG]

    This for +$30,000 and +4 lbs:

    [​IMG]
    Or this for + $50,000 and +8 lbs (IFR):
    [​IMG]

    (oh yeah and those are the prices without the autopilot).

    I'm starting to consider maybe just keeping the thing VFR-only, but I go back and forth day to day. I have about 6 months to decide.

    Interested if anyone has any ideas about long-term reliability between the choices in terms of future maintenance hassles, resale implications, etc. I don't intend to ever sell the airplane but I don't want to have sometehing weird that no one would want if I did need to.
     
    Last edited: Mar 12, 2021
  28. Cluemeister

    Cluemeister Line Up and Wait

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    C!
     
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  29. GeorgeC

    GeorgeC Administrator Management Council Member PoA Supporter

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    It's a Cub. Minimal VFR. Leave a blank in the middle for a RAM ball so you can mount an iPad or Aera since it's gonna change every few years anyway. Put in a 345 so you get an AHRS that can drive an AI in case you need it.
     
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  30. Ryan F.

    Ryan F. Cleared for Takeoff

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    Your call -- all looks nice. If it were me, I'd go basic! It's a Cub, that's part of what makes them so enjoyable. That VFR-only panel is still far more capability than most would ever dream of needing in a Cub. The idea of a modern digital autopilot in that little bugger is mind-bending... impressive, but... why?
     
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  31. farangutan

    farangutan Pre-Flight

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    If I spent hundreds of thousands on an airplane I'd want it to legally be able to punch through an easy layer of clouds to get in or out. Those panels look very slick, but I think you may be able to save money somewhere and I don't know enough to advise on that.
     
  32. asicer

    asicer Final Approach

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    Basic VFR. It's a Cub. Save money and weight (those ounces add up).
     
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  33. Peter Anderson

    Peter Anderson Pre-takeoff checklist

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    It’s experimental. You don’t need Garmin stuff. You could do a IFR panel with an autopilot much cheaper by looking at other companies. GRT is a great example of affordable stuff. If i was building a plane I would want it to be IFR capable just in case.


    Sent from my iPhone using Tapatalk Pro
     
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  34. farangutan

    farangutan Pre-Flight

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    Those carbon cubs have incredible useful load and just two seats to fill. Less than a dozen pounds for some peace of mind and also to maintain IFR currency in your own plane without having to rent a plane with the avionics. If the budget allows it, go for the IFR or set yourself up to add IFR capability on your own in the near future.
     
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  35. farangutan

    farangutan Pre-Flight

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    Another note, getting caught unprepared in IMC trying to set yourself up for an approach and you will wish you had an autopilot. I don't have a working one and a few times I wish I did.
     
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  36. Stewartb

    Stewartb Final Approach

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    Much of why I like a Cub is when the weather is bad I can land just about anywhere and wait it out. Where I take a Cub doesn’t work with IFR. If I happen to get into a bad visibility situation? My G3X Touch is more than capable if providing me what I need to get out or get down. Way better than round gauges. So why do I have an auto pilot? Because my total investment to add it was $1500.00. Do I use it much? Nope. Occasionally I use the wing leveler. I call it my chicken switch. Not for why you might think. I can activate the AP and eat a sandwich or a piece of chicken and let the plane fly itself. And I like the idea that I can have a pinch hitter control the plane on those days I’m getting beat up in turbulence and just need a break. CC’s option prices are way too high but that’s consistent with the price of their planes.
     
    Last edited: Mar 13, 2021
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  37. GRG55

    GRG55 Final Approach

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    ^^^I have a similar view of things. I use my Husky is a VFR airplane in the back country. Even though it is IFR capable (courtesy of the prior owner) it's not something I'm going to use for any intentional IFR work.

    It is so darn stable in pitch when trimmed out it doesn't really need an autopilot for that axis. But I do have a wing leveller that can follow a heading, for the same sort of reasons Stewartb described above. It's nice when the fishing hole is bit of a cross-country hike to get to.
     
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  38. Narwhal

    Narwhal Pre-Flight

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    Stewart, thanks for all your help! Do you have any problems using the G3X as the way to tune your comm radio? CC tries to put GTR-200 in all their G3X builds because they say it is cumbersome (plus there is going to have to be a remote radio even if one isn’t in the panel). I have heard some people say it is fine though. I can’t see your whole panel in the earlier photo but it looks like you use your G3X to tune your comm radio.

    I am going to tac aero to train and try this stuff out in a few months too, and will probably make my decisions after that.
     
  39. Stewartb

    Stewartb Final Approach

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    Comm and txp are remote and tune thru the G3X. Very easy. Tap the top margin where frequency is displayed and a screen opens for tuning. Same for setting altimeter, entering fuel qty, and so on.
     
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