arj1 wrote:
Not even a license/enabler key?
If you buy the G5 as an HSI, no. If you buy the G5 as an AI then it is limited to being just an AI. But I don’t know if that is because of a block in the software or lack of connected sensors (e.g. magnetometer) for the AI version.
Airborne_Again wrote:
There’s no difference between the certified and non-certified versions, except the price and the paperwork. You can switch a certified G5 between HSI and AI as well. Ask me how I know.
Not even a license/enabler key?
HBadger wrote:
Yes sorry, they are all called G5, but there is still a difference between the experimental version vs the certified:
G5 is either Attitude Indicator OR DG/HSI USD 2,595.00
G5 Experimental (can be switched between EFIS and DG/HSI) USD 1,340.00
There’s no difference between the certified and non-certified versions, except the price and the paperwork. You can switch a certified G5 between HSI and AI as well. Ask me how I know.
Airborne_Again wrote:
Do you mean G5?
Yes sorry, they are all called G5, but there is still a difference between the experimental version vs the certified:
G5 is either Attitude Indicator OR DG/HSI USD 2,595.00
G5 Experimental (can be switched between EFIS and DG/HSI) USD 1,340.00
The configuration I would go for is this (prices in USD):
GMC507 1,239.00
G5 Experimental (can be switched between EFIS and DG/HSI) 1,340.00
G5 Battery pack 250.00
Servos 3x GSA 28 865.00 = 2,595.00
GAD™ 29 data interface adapter 499.00
GMU 11 magnetometer 370.00
But I suppose it has accelerometers to complement the barometric feedback.
Yes; internal. More instant than using an external attitude source like a KI256. They just aren’t accurate in absolute terms; for that you need a KI256 or some such, but then one rarely needs an “absolute pitch” because the pitch is integrated up or down anyway to achieve altitude hold. PIT mode is dead useful though for climbing to or near the operating ceiling.
the fact that I don’t have HDG function automatically means I cannot fly NAV
Well, one “could” do it, all you need is a crude yaw gyro, which is a peanuts-cost chip. But it should also be possible to track a GPS track without any yaw or HDG source, if you have a 5Hz+ GPS (which is standard today but wasn’t 20 years ago). It is much harder with a VOR/LOC because you just get deviation data, nothing absolute which could be tracked.
HBadger wrote:
don’t need a GFC 500 but instead can go with a G5X + GMC507, which changes the cost equation somewhat. Choices over choices :)
Do you mean G5?
That’s still a GFC500 system. The GMC507 is just a mode control panel, which you need with a G5 but which is optional with a G3X. The actual A/P computer is in the G3X or G5, depending on what you’re using. According to the Garmin GFC 500 web page, possible GFC 500 configurations are:
G5 + GMC507 + servos
G3X (+ optional GMC507) + servos
G500 + G5 (+ optional GMC507) + servos
All three variants are possible in both certified and non-certified aircraft.
Peter wrote:
It is difficult to have a stable control loop which runs LOC or NAV as the primary, or ALT as the primary, because you get a delayed feedback on these. In fact barometric feedback is especially crappy.
Interestingly, the KAP140 holds altitude very well, even though it’s not pitch based. But I suppose it has accelerometers to complement the barometric feedback.
Interesting. so it is all connected: the fact that I don’t have HDG function automatically means I cannot fly NAV. The Garmins do have heading information though, so it seems a fixable communication error.
I just learned that since I am flying an experimental, I don’t need a GFC 500 but instead can go with a G5X + GMC507, which changes the cost equation somewhat. Choices over choices :)
You cannot have a HDG mode without a heading source, which in GA avionics is normally a fluxgate magnetometer.
In fact GA autopilots cannot fly NAV (GPS or VOR/LOC) without a heading source, because they fly HDG as the primary target and then use the GPS/VOR/LOC deviation to adjust that. Same as they fly PIT as the primary target and use the ALT/GS deviation to adjust that. It is difficult to have a stable control loop which runs LOC or NAV as the primary, or ALT as the primary, because you get a delayed feedback on these. In fact barometric feedback is especially crappy.
Hmm, so based on the discussion, it’s the “safer bet” to just go with the AT-1 by Air Avionics. Price is similar to the PowerFlarm Fusion and at first glance I don’t see any advantage of the PowerFlarm Fusion over the AT-1.
Peter wrote:
BTW what is wrong with the TruTrak? Possibly there is no pitch trim, so altitude hold (ALT), VS, etc, become a bit “interesting”. It also can’t fly a heading, only a GPS track. But while the GFC500 can fly an ILS (very relevant to Europe) it can’t do it without GPS (it disconnects the GS if it loses GPS, reportedly).
The TruTrak is great on paper. It’s just that neither the original builder nor the people I talked to so far could get it to work the way it’s intended. Currently, it flies TRK mode, IAS climb to target alt, VS descent to target alt and ALT hold. It somehow receives GPS data which it needs for TRK mode. But so far no one could get it to work in GPSS, GPSV, HDG, NAV mode. It also doesn’t take the altitude bug from the G600 and I am not sure if it is capable of this even in theory. I haven’t tried ILS yet and not sure if it would work without GPS (which would make it superior to the GFC500 in that regard).
It is inferior to the GFC in two respects:
1) user interface is not intuitive
2) it doesn’t fly as smoothly. it is not 100% stable in straight and level flight, it’s always a bit “chasing”. And when e.g. changing altitudes it is quite abrupt. It feels as if the servos are more “crude” than with the Garmin system (I know the GFC700 very well) and cannot physically be as precise.
I do have electric pitch trim, but it is not coupled with the TruTrak. It gives a visual indication when it wants me to trim however.
All that being said, the more I think about it, the more I am inclined to give the TruTrak another shot:
1) Will get the TruTrak sent to USA to get the latest firmware on it
2) Will update the G600 and GNS530W onto the latest firmwares
3) Check if the wiring is all done correctly between the Garmins and the TruTrak, then also double check the software settings (e.g. ARINC 429)
4) Install the AT-1
I still need to figure out if there is an additional benefit of replacing the GTX-328 Mode S transponder (I guess ATC would be more happy to have ADS-B data, but for collision avoidance maybe the AT-1 is enough?). If I replace it with e GTX345 I have ADS-B In/Out, it integrates traffic into the Garmins, but I am missing FLARM. So the AT-1 + GTX-328 seems better still.
I’m also wondering what the use of the GNC-250XL GPS/COM is. Why did the builder put it there? The GPS functions are made redundant by the 530 / g600. and the COM doesn’t support 8.33MHz, so I basically use it exclusively as a 121.5 standby COM2.
i’m surprised no-one brought up ADL Golze weather yet. It seems a ADL150B would be great (the ADL190 and ADL200 have ADS-B Traffic but that is already taken care of by the AT-1). The ADL150B should integrate with the G600, which would be awesome.
