Auto pilot certification?

Flying_Monkey

Member
Joined
Sep 5, 2019
Messages
32
It's understandable that Dynon is using it's engineering resources to do the design work on the types with the highest numbers of possible sales. The frustrating thing is that the experimental version of the autopilot can be pretty much installed on any thing a builder builds so long as they don't mind making their own mounts and control rigging.

I suppose the FAA is putting Dynon through a lot more hoops than common sense would dictate. As far as I know Dynon's autopilots haven't caused a lot of problems for all the experimental types they've been installed on. Unless the physics works differently for aircraft that fly using experimental certificates vs. type certificates. A lot of time spent doing proofs does not seem to be warranted. There are conceivably type designs that exhibit flight properties that might not be safe to fly with an autopilot. I don't know of any TC'd aircraft that are in that category since they would probably not get TC'd because it would be hard for a human to fly them as well.

The other thing that probably slows Dynon down is that they feel like they need to have all the installation parts (mounts and rigging parts) developed and on the shelf before they add a type to the AML. That isn't an FAA requirement. It's fairly common that low volume STC's installation designs that require the A&P to fabricate sheet metal parts like brackets. Most of the rest of it could be solved by calling out standard AN parts.

The only way Dynon is going to make a significant dent in their backlog is to hire an engineer to collaborate with type clubs or other type owner groups to develop designs and approved data and walk it through the FAA. Dynon could charge the groups for the engineer's time collaborating with the outside groups. As part of the contract for that collaboration, the resulting design and data could be signed over to Dynon.

A side benefit of that to Dynon would be that they would be getting their engineering underwritten by groups of owners that are willing to put their resources (read time and money) into the process and are likely to actually result in system sales. That takes it out of the realm of a market projection committing a lot of company time and money.
That all makes sense to me. I totally understand that they need to go after the models that will generate the sales and some of the common birds like PA28 have been dominated by Trutrak already so maybe they figure that is a lost segment? Ether way I am super happy with my HDX system - it is just amazing. The certified aircraft world definitely has its drawbacks. After I dont need the hauling capacity of the 6 I'd love to think about building an RV.... :)
 

Dynon

Dynon Staff
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Jan 14, 2013
Messages
13,492
Location
Woodinville, WA
The other thing that probably slows Dynon down is that they feel like they need to have all the installation parts (mounts and rigging parts) developed and on the shelf before they add a type to the AML. That isn't an FAA requirement. It's fairly common that low volume STC's installation designs that require the A&P to fabricate sheet metal parts like brackets. Most of the rest of it could be solved by calling out standard AN parts.
This part is actually not that bad, relatively. Once we've done the engineering and design, which is a prerequisite, we're pretty good about getting parts and kits to market. There are lots of reasons that it's more complex than E-AB AP installation kits, but a major one is that even though we wished that airplanes should be basically "the same" for their model run, the reality is different, and reconciling those differences to come up with a workable installation is often non-trivial (to say the least). The majority of the time and effort is in the former. The latter makes it easier for everyone to actually install (ie, a business decision that we think minimizes costs for everyone involved, which we care a lot about)
 

Bill Putney

New Member
Joined
Jul 28, 2019
Messages
14
Location
Port Townsend, WA (0S9)
You'd be in luck with the Navion. Even though there's been half a dozen models they all have the same control linkages. One design would work on all of them. They've had autopilots from Brittain, S-Tec and Century to name a few. Navions have also been made into remotely controlled target drones by the military and fly by wire test beds by NASA and several universities. The point is that they are aerodynamically stable and straightforward to control by servos.

The problem for me is that we're probably about 600th on the list of types you folks will get to. I'll be too old to fly by the time you get around to it. I'd like to offer some other ways to get your AML to include more of the obscure types that won't make it so difficult financially for Dynon. I know one Navion owner who is taking his airplane into experimental, just so he can install an autopilot. That's a pretty extreme measure to take to do something as simple as add 2 servos and a couple of lengths of control cable. 1000's of experimental aircraft have been equipped with better autopilots than the certificated types can get close to. The setup instructions don't vary which tells me that Dynon has designed these to work across a broad range of aircraft designs with out a lot of hardware hand waving. I know S-Tec has probably tried to convince the FAA that autopilots are so hard to do that only they can do them, but I think we've kind of seen through that by now.
 

chousley

New Member
Joined
May 15, 2020
Messages
12
I have a C172 with Dynon HDX SkyView w/ Autopilot. Have been having continuous issues with ALT hold. I will have the aircraft perfectly trimmed out for straight and level flight at a cruise power setting. Once I engage the auto pilot and Altitude hold if any conditions other than
completely smooth air I will get a "Trim Nose Down" message followed shortly by a "Pitch Slip" message. Autopilot will aggressively pitch and slow the aircraft by 20 KTS or more while only chasing 20 - 30 ft of altitude. Any ideas on a fix?
 

chousley

New Member
Joined
May 15, 2020
Messages
12
Not sure. Brand new owner and was not involved with the initial Dynon install (Thrust Flight / KADS) I will research that?
 
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