Comparing and Contrasting: GRT and Dynon

As some people know, I have been flying with the dual-screen GRT Horizon 1 EFIS for a little more than two years (and 670 hours) in my RV-8. I was a fairly early adopter, and use it in IFR conditions whenever the need arises. When I started designing my panel, electronic flight displays were just beginning to become available, and my first iterations actually had a Dynon D10 as an ADI, along with an HSI and something like a VM1000 as an engine monitor. My first trip to Oshkosh gave me a chance to examine the four or five different EFIS systems available at the time, and I came away with the decision to go with GRT when I saw the sunlight readable displays and talked with the company founder and engineers. I have a good working knowledge of aerospace guidance and navigation systems, and liked what I saw in terms of design philosophy and robustness. This was clearly something that I could fly with! Coupled with the engine monitoring system that GRT had been building and selling for many years, I felt this was a great integrated solution that fit my requirements.

I have written a lot about flying the Valkyrie with the GRT systems, and have hopefully given people insights into just how flexible and informative it can be. This allows me to make maximum use of the airplane as a travel platform, as well as a local aerobatic machine with systems that I don?t have to worry about hurting despite g-loads and unusual attitudes. What I have resisted doing is commenting on how GRT compares to other available systems, because, quite frankly, I have not had enough experience (to this point) with any of the other systems to make a valid comparison. I could say that the GRT was GREAT ? but that didn?t mean that other systems weren?t as well. The recent project to upgrade Louise?s RV-6 that included a Dynon D10A and D180 has finally given me a chance to use these other systems enough to allow a valid comparison, so I thought that I would make a few comments that might help folks make their own decisions when choosing a glass cockpit option for their projects.

This is in no way intended to be a complete and final review with a firm recommendation as to which one I think anyone should buy! I would never be so presumptuous as to make that kind of recommendation to anyone ? there are too many variables in mission and means (what you intend to do with your panel, and how much you can afford to spend) for that to be useful. I have told people that comparing two different EFIS?s can be like comparing apples to oranges ? especially when you consider that some folks like apples, and some folks like oranges! There is no single right answer. But I can make some comparisons in a few areas that are important to me. I?ll say up front that I would choose the GRT again for my purposes. I also understand and stand by Louise?s (and my) decision to use Dynon in the -6. Having two planes that can be used as required allows us to optimize each one differently.

Once people have chosen to go with glass for their panel, the decision on which system to buy can and will be made on many different factors, some of which are inter-related. Sometimes, a particular factor (such as cost) will drive a person?s decision. In other cases, they can be equally weighted in terms of mission requirements. It is important to be honest about both your resources and your mission requirements before getting into the game. In general, we all have to compromise on requirements to fit things into a budget. Among the many ways to compare EFIS?s, are:

Features (what can it do?)
Reliability (How likely is it to continue doing it?)
Cost (What?s your budget?)
Company Stability (How long have they been around ? will they stay around?)
Maturity (How many units are in the field, and for how long?)
Robustness (both hardware and software)
Upgradability (can the system grow? What will new software features cost?)
Will it fit? (Does it work in your panel?)
Compatibility (Will it work with other systems/radios/GPS?s?)

Cost

Comparing cost can be tricky, because the systems have to be truly comparable. It?s easy to price a D180 with full engine sensors and compare that to a GRT Sport, with engine sensors ? you?ll find the Dynon to be cheaper ? but it doesn?t have the moving map capability that the GRT offers. Add in a GPS (to the Dynon panel) that will give you a moving map, and the prices come much closer. I?m not really going to say much more about cost because frankly, everyone can go out and crunch their own numbers. But to be fair, you have to start with a list of features, and then make sure that you include equipment to cover all those features if you want the results to be valid. Another thing to remember is that if you are building an airplane with a glass cockpit, the difference between systems might be a couple thousand dollars ? and that is a pretty small fraction of the overall finished aircraft cost. If you save $500 - $1000 and settle for less features than you want, you will probably be disappointed once you?re flying.

Reliability

OK, this is going to be subjective because quite frankly, reliability is better measured statistically rather than anecdotally, and a few units does not qualify as a statistical sample, but I can relate my experiences. My GRT units have very low serial numbers, yet they all powered up from the very start and ?burned in? during the build process for hundreds of hours in the workshop. After a month or two of occasional power-on testing, I experienced a slow ?roll-off? of the attitude, and called GRT. Within minutes, I was talking to Greg, the designer, and he asked me to ship the unit right back at his expense. The next day, I heard back that I had a unit with gyros from their original supplier which he was no longer using. The unit was repaired and sent back within a couple days, my building was never slowed down, and I have not had a single problem with the hardware ever since. I have had one time that I had to reload software due to my own mistake ? I let the unit go down ?dirty? by leaving the battery on, and had to load software from a thumb drive (I did this while taxiing to the runway). All software upgrades have installed as advertised and I have not experienced any bugs.

The Dynons had a few growing pains, all of which have been dealt with quickly by Dynon. Louise had to send the original D-10A back twice in the two years that she had it, once for a heading problem and the second time for a failed (dark) display. After building up the new panel with the new D180 and old D10A, we had a display board failure of the original D180 during a software upgrade. Dynon sent us a new one overnight, and let us return the dead one at our convenience. During troubleshooting to figure out why the DSAB (Dynon Systems Avionics Bus) wasn?t working, the D10A locked up hard, and they sent us a refurbished unit under the same arrangement. Then they sent us a new PAIR of units to further troubleshoot the DSAB problem, which turned out to be a floating socket in a connector in the harness. So we?ve had more trouble with the Dynons, but Dynon had been quick to address them.

Overall, based on this very limited experience, I have a lot more faith in my GRT?s than I do in the Dynons. However, the pair of Dynons give us two attitude platforms, so it is unlikely that they would both fail at the same time, unless there was a common software issue. Nevertheless, based on my experience so far, I have to say that I feel better with the GRT?s.

AHRS Design features

To me, the heart of any EFIS is the Attitude Heading Reference System and Air Data Computer. Different companies have different acronyms for their systems, and GRT uses AHRS for theirs, but the bottom line is that what I see on the display (in terms of fancy graphics and cool features) is inconsequential if I can?t trust the navigation base to be stable, accurate, and reliable. The have been many threads on the VAF forums discussing how the various systems use airspeed for aiding the Nav solution ? Dynon uses airspeed, GRT doesn?t (as best I can tell). The GRT has never given me a bad in-flight solution. I had a chance to look at the Dynon in flight without the airspeed (I screwed up the connections on the first flight, and it had no pitot) and was able to see it have significant lag in both pitch and roll. But when hooked up properly, It appears to be stable and tumble-free, based on some limited aerobatics. I have talked at length with Greg of GRT about their AHRS software and hardware design, and am comfortable that it uses proven, state-of-the-art concepts and is reliable and robust. I can?t comment on the Dynon?s design, as I am not familiar with it, but then again, we have two of them. I actually have found it a little disturbing to have two different Air Data computers in the two Dynons ? while the attitude displays always seem to agree, it it hard to get the two altimeters to match ? and harder still to keep them matched. My GRT and standby altimeter match perfectly to 20,000? when I have the IFR cert performed ? I am not sure how well the Dynons will do yet. Remember the old saying about redundancy ? the man with two watches never knows for sure what time it is. The GRt does a great deal of internal checking on itself, and the software design is fairly sophisticated to make this happen

Integration

There is no doubt that one of the advantages that the GRT Horizon 1 has over the Dynon is that it?s moving map gives it the capability to truly integrate piloting/cockpit tasks. Whereas the Dynon gives you traditional cockpit information in an electronic format, the GRT takes that information, combines it in a way that multiplies its usefulness, and adds the capability to use the multiplied data for control. That?s a lot of stuff in one sentence, so let me explain. The Dynon has a good PFD layout, giving the traditional horizon, compass, airspeed, altitude, etc. It also has a nice HSI layout which can be driven by GPS or VHF Nav data. And of course, it has engine and fuel monitoring information. Coupled to a GPS it can give you more useful information on fuel state, such as miles per gallon, and fuel at the next waypoint. This is vastly superior to flying with traditional instruments and having to rely on off-line computations to tell you how the fuel will hold out. Now jump ahead to the GRT, which includes a moving map and database. With a flight plan in the system, or supplied from a GPS, it can tell you the expected fuel at all the waypoints on the route ? at a glance. When you bring up the HSI, it not only gives the familiar needles and pointers, but overlays this information on the IFR map, so that you see the locations of waypoints, intersections, and runways. Navigation is a no-brainer when flying an approach ? it is clear where you are at all times. The GRT also allows you to run multiple GPS sources, and to have simultaneous (and different) internal and external flight plans, so that you can be running one and ?what-iffing? with the other.

In addition to integrating the navigation picture into the equation, the GRT also integrates the autopilot into the system. You can control the autopilot from the EFIS Screen, either coupling it to the internal or external flight plan, or to the heading pointer on the moving map. This means that you can ALWAYS use the EFIS to control the autopilot, and don?t have to look elsewhere for information, then translate it to the A/P The Dynon (at least at this point) don?t have anything to do with the autopilot, but since they don?t really have any significant navigation data, this really isn?t to be expected. The GRT also gives you a full terrain database which allows for terrain warnings right where you are looking ? on your PFD or moving map. Granted, the moving map does not look like a sectional ? it is more of an IFR tool, showing waypoints, airports, an Nav aids ? but this is fine if you are IFR. For an additional cost, the GRT also allows you to display XM weather on the moving map, along with waypoints, along with terrain, etc?.in other words, it puts all of the information in one place for the pilot to absorb. You can twist the knobs to move the course line clear of weather and the autopilot will take you there ? simply amazing!

Features

This is probably one of the toughest and yet most important areas of comparison between any EFIS devices. There are so many different features that you can have, and in many cases, they are difficult to compare on a one to one basis. I will say up front that I believe the feature set of the GRT system to be much more complete and richer than those of the Dynon. But then, the Dynon is not as expensive of a system as the GRT Horizon. This is where the ?Apples and Oranges? factor comes in. However, many (but not all) of these features require nothing more than new software to make them appear ? I predict a software arms race is in the making!


The Dynon?s that we installed basically provide the functions of traditional gyros, airspeed and altimeter, engine monitoring, and fuel flow monitoring. The GRT does all of those things, but adds navigation functions, including a moving (IFR) map, flight planning capability, autopilot control, synthetic approaches, and flight recording. The GRT HSI functions as a full-featured RMI, displaying bearing pointers from two different Nav sources at once, as well as overlaying map and course information. The Dynon?s HSI can use either GPS or VHF Nav data, but I haven?t found a way to do both at the same time.

The GRT can display Nav CDI information on either (or both) the moving map/HSI or the PFD. The Dynon can display this on the HSI, but I haven?t found it on the PFD. This, of course, is again only a question of programming ? once the data is in the box, a clever programmer can do just about anything with it. One of the most remarkable features of the GRT (that it shares with even higher-end systems) is the ?Highway in the Sky? guidance boxes that are used with synthetic approaches and can be coupled to the glide slope. I have found no more intuitive method of flying an approach than keeping the velocity vector inside the boxes ? it is extremely easy to do. In fact, I think it makes the need for an approach-coupled autopilot more difficult to justify.

Clearly, the GRT has more features because it has more hardware options ? such as weather and terrain (and even traffic!). The Dynon does not yet support these function, and I don?t know if they are in the works or not. I am impressed with what the Dynon does, and it does those things fairly well, make no mistake about that ? but in the feature department, it is hard to beat the GRT (even with a more expensive unit).

Company Stability and Responsiveness

I am fairly well convinced that the recent ?explosion? in the number of companies marketing electronic flight systems is not going to last ? there are only so many airplanes being built, and it is far more difficult to build a successful business than it is to design a flight instrument (which isn?t easy in itself!). ?Hobby? businesses (and neither GRT nor Dynon fall into that category, in my opinion) are going to fall by the wayside. In this respect, I think we?ll end up with a reasonable number of survivors that will give a choice all along the price curve. The survivors will be the ones that not only have a good product at the appropriate price, but have a reputation for honesty, integrity, and going the extra mile for their customers. I have had incredibly good results with GRT over the more than three years that I have dealt with them. They have always responded to questions, and been quick to provide service the one time I needed it. In addition, they have a remarkable policy on payment and delivery. Order when you want ? they will not charge you until they have a unit to ship. They are also very conservative about not over promising ? they will not talk much about what will be coming ? they prefer to deliver first, and then talk about stuff.

My relationship with Dynon is much shorter, but so far has been pretty good. Once we got into troubleshooting mode with Eric at Dynon, he went the extra mile sending us replacement units to try until we found the fault in the system. I felt like we were able to communicate on a technical level, and exchange ideas on the problem as we worked toward a solution. I can?t say whether or not everyone gets the same treatment as Louise and I did ? I certainly hope so. As EFIS manufacturers see interesting features in other company?s software, I suspect that the functionality of the surviving systems is going to converge, making it harder to tell them apart, At that point, attention to customer?s needs is going to become much more important in how builder?s select the systems they will buy.

Summary

In summary, I am not sure that I have really done a comparison between the GRT and Dynon systems so much as I have pointed out the features and the differences of both systems. I have tried very hard not to tell anyone which one they should pick, as that is none of my business ? I just hope that I have honestly laid out some of the similarities and differences, as well as what I found to be useful and/or lacking in each system. Given the two different systems in their current state of development, the GRT is the more complete and feature-rich choice. It is my choice for serious IFR work. The Dynon is a good lower-priced option, excellent for VFR cross-countries, and OK for lite IFR (A term that many people do not like, but one that I believe is realistic if you are willing to ruthlessly enforce personal weather limits). The truth of the matter is that very few RV pilots are going to use their airplanes for extensive IFR work. For that matter, I would bet that the percentage who routinely set out on long (half-continent or more) cross-countries is probably less than those of us who do. My fully-IFR airplane has made 10 very long cross-countries in the past year, and many, many shorter ones, and I?ve only shot a couple of approaches for real in that time. I thoroughly enjoy having all of the features of the GRT system even for VFR cross-countries, because it gives me so much insight into the big picture The Dynon?s give less, but that is probably enough for many people.

I love analogies (if you haven?t guessed by now) and this is sort of like comparing a Mazda Miata to a Ferrari. Both are sports cars, and both are a blast to use. The Ferrari can beat the Miata hands-down in a full-out performance situation ? but unless you go to a race track, where can you legally use anything more than the Miata can provide? Yet some folks want to own the Ferrari because they appreciate what it is, and what it can do (and might even occasionally use it slightly above the posted limit?.). The GRT provides a capability unheard of in light aircraft until only recently ? it can do just about everything useful that you will find in a big airplane EFIS (when coupled with a sophisticated IFR GPS). The Dynon serves as an outstanding replacement for traditional instruments in a cost-effective manner. I am sure that the features and functions for both will continue to grow, as will both company?s customer base. It?s good to have choices, because everyone has different needs. And that said?.rather than blather on pedantically, I will open the floor for specific questions!

(Please note ? I cannot address questions or comments about any systems other than the GRT or Dynon, because I haven?t flow them?well, with the exception of some experimental stuff that NONE of us can afford!)

WOW, thanks

Great writeup, Paul, and much appreciated. I'm finally getting around to the buy- the-avionics part (I'm on the 'interminable build plan') and got the same impression of GRT from talking to them, researching the stuff and following user posts. They made a lasting impression when they indicated that they designed it like it should be then priced it accordingly. Works for me.

That was a few years ago. Lately, I have to admit being tempted by some of the new dazzling displays, etc. but just don't get the same warm, fuzzy feelings like I do with GRT. A flying RV7A buddy and I were discussing my panel just this PM.. very timely.

Again, thanks for taking the time to share your experience and insight.

John

Good stuff.. at first I saw post after post... didn't know if you were just talking to your self.. or if we should read it..

Brilliant and timely!

Paul,

Great stuff, thanks! I have from the beginning felt like I'd end up with GRT's in my panel and this confirms their suitability to my mission (lots of cross-country with IFR "light" meaning planned exclusively to punch up or down through a layer).

Your comment

In fact, I think it makes the need for an approach-coupled autopilot more difficult to justify.

Click to expand...

really got my attention. I have been leaning heavily towards a TruTrak VSGV with the idea of having an approach-coupled 2-axis autopilot. I've even gone so far as to install the trim-sensing pitch servo already. The downsides compared to my other choice, the ADI Pilot II, are cost and not having the integrated AI as a backup. I like the form factor of the Digiflight more (2.25") and for my mission, the 496 could actually function as a backup for everything. I am several months from decision time on the panel so now is a good time for others' perspectives.

For context, my first stab at a panel plan is:
- Dual Screen GRT, Single AHRS, EIS in panel.
- Garmin 430W
- Garmin Xpndr
- Garmin 496 panel mounted on an arm, switchable from right to left so it sits under the pilot's GRT screen, XM weather and audio included
- Icom A6 handheld, panel mounted on an arm w/ship's power, dedicated antenna, and connection to ship's audio, switchable from right to left so it sits under the other GRT screen
- TruTrak autopilot - Digiflight II VSGV or ADI Pilot II
- homebrew Lift Reserve Indicator
- backup airspeed
- backup altimeter
- PS3000 intercom

Here is my first mockup of it:


I'd really appreciate your thoughts and anyone else's with TruTrak/GRT experience, specifically regarding the DII-VSVG vs. the ADI Pilot II.

Thanks in advance,

George

Well Paul, now I know how you got to 3000+ posts

Thanks for the EFIS lesson.

Paul,
Thanks for the write up on the two systems. While you've spent lots of hours with the GRT systems, it appears you've done some fair research and work with the Dynon products as well.

One thing I would ask you to describe is how capable you find the systems of doing everything at once. Since we are talking about single screens that can do EFIS, EMS, HSI, and Mapping all at once, do you feel like you can really do all of that effectively on one screen, or is a second screen a requirement? Also, what is the configuration like for both systems, setting up alarm values for the EMS and airspeed colors, and what's the wiring like?

I'd like to look into the pricing issue a bit more though. While you ask people to price things themselves, I think it's also fair to discuss the price for the actual systems described in the post. Price has always been something that Dynon works really hard at, and we are proud of our pricing, and how affordable it has made EFIS units for the experimental market.

Here's how we see the pricing for the systems you described:

Dynon D180, bright screen, probes, wire harnesses, fuel flow, HS34: $4940

GRT Horizon HS, EIS, GPS, ARINC, Fuel Flow, MAP, Fuel Pressure: $8790

That's a pretty huge difference, not the couple hundred dollars you referenced.

Weather on a GRT unit is $1500- you can get a standalone 396 for $1795, so if you want weather, a Dynon+396 is WAY cheaper than a GRT system, and just as legal as the GRT.

If you're a real IFR pilot, the GPS inside a GRT, or any other experimental EFIS isn't legal to fly. So you're gonna have a 430 or 530. In that case, all you need is an ARINC-429 connection for your HSI, which both of the systems above have. You don't get the ARINC-429 with the GRT sport until you buy the unreleased Sport HX (which they announced in April 2007) and the ARINC box, so you can't do lots of the IFR activities with GRT until you spend lots of $$ over a base sport.

GRT makes some great stuff, and it does lots of things we don't (and we do some things they don't as well). But $4000 will get you a lot of other toys for your cockpit, many of which are legal to use in the IFR environment. GRT does make a great Sport series of units as well, but they don't do everything you described, so people should really look into the available feature limitations there if they are going that way.

I agree that people should add it up themselves to see what they are getting. If price is no object, Dynon is not the system for anyone out there, but for people looking for performance per dollar, we still firmly believe that there is no better choice than Dynon.

A few other comments, just to clear up some points:

We'll put CDI and Glideslope from a GPS or VOR right up on the PFD. It's in the clutter menu.

We can do dual RMI pointers from seperate sources on the HSI as well.

The Dynon EMS systems do full engine data recording, and our next release will do EFIS and GPS logging.

We never take payment before shipping, just like GRT.

It sounds to me like your one GRT unit failed before you even got to fly it, and you had troubles with your Dynons as well. Why does this lead you to believe the GRT is more reliable? Many of the problems you had with the D180 were due to wiring (as you mentioned in another thread).

Finally, a personal question I have always wondered about: How do the GRT devices get the glideslope for the HITS display? Do they just always assume 3 degrees to the GPS designated runway, or do they use the actual glideslope that is being received by the LOC receiver in the plane?

Thanks!

Thank you, Paul, for an extremely well-written and timely summary. I'm ready to begin cutting holes in my panel, and you've verified all of my impressions, especially about how the GRTs and Dynons will integrate with other systems in my airplane, as well as with how they will integrate with the pilot(!).

I plan to enjoy the benefits of two GRT EFISs and a Dynon D-10A, so it'll be interesting to compare their operating characteristics, quirks, utility, and accuracy side-by-side every time I go fly.

Paul, Thanks for taking the time to make such an excellent write up! Its really difficult to find a real world comparison of any of the current crop of EFIS, especially from someone who has a good grasp of what's going on behind the pretty pictures. How did the installations of the two systems compare?

Pete

Quick Answers....

I am headed out the door for a vacation, but a few quick answers....

Autopilots: I may be a bit on the fringe, but I prefer to hand-fly approaches - at least in pitch, so I am happy with the simpler Tru-Track units. I have a Pictorial Pilot and an Altrak in the Val, and we put the ADI Pilot II in Mikey - they are essentially equivalent in function, and both give you a display to help hand fly if everything else gives up. I consider some sort of independent attitude platform ESSENTIAL to flying glass in IFR, and that is how I achieve it in my plane. On Mikey, of course, we have two separate platforms with the two Dynons, and a third in the ADI.

Multiple screens: Yes, to display a lot of information, you need to have a lot of screens. Dual head GRT is great. If I were building a DYnon system from scratch, I'd probably go dual D180's to get the real estate. The D180 and D10A is adequate, but the D180 is FAR easier to read (and the Superbrite option that Louise has is quite nice!)

Pricing: I'm going to let everyone add up their own numbers, because it isn't hard to do, but the numbers you posted aren't entirely direct. To the Dynon you have to add a D10A to get the system that I was reviewing. And then you would have to ad in some sort of moving map, so the spread between the two systems is nowhere near as dramatic as it appears. I don't use internal GPS's in any of the EFIS's, since I fly IFR, and use separate IFR certified GPS's for that - in the case of the Val, a 430, and in Mikey, we have elected to go VOR only for IFR, with the 396 being the GPS, map, and weather box. If a person is already going with a GRT, then adding XM weather is cheaper using their box than a 396/496. If a person goes with Dynon, then the 36/496 is a great option (that's what we did with Mikey).

New Fetaures: Thanks Dynonsupport for pointing out what you're working on - and what I have yet to find in the existing units! I tried hard to review what is actually THERE in both systems, and not try to predict what is going to happen. As I pointed out, software features are going to be limited only by the creativity of the designers and the demand of the users.

Installation: This is pretty straightforward in both cases - I'd give the degree of difficulty the same score, and it's not high if you have some wiring experience.

Paul

hmmmmm

post removed, as it seemed to be to harsh for some. that was not the intent. and it has come to my realization that communication without an existing interpersonal relationship leads to people getting offended and feeling insulted. constructive criticism does not always present itself as such.

Panel Decisions

Paul,
Thanks for the writeup and the opportunity to see both panels earlier this month.

What changes, if any, would you make in your panel design if you were building this year (given the same mission and budget target you started with during your original build)?

In other words "if I knew then what I know now" about flying with your GRT...would the rest of your panel look the same?

Thanks,
Mike

Yep due to he major differences in the feature set of Dynons vs GRT, a more appropriate comparison will be with GRT and MGL's newest offerings!

Can't wait till someone can compare those two...At first glance, MGL seems to have most if no all of the GRT's features at close to half the price. The screen resolution has yet to win me over yet. I hope to see one at Osh. so can tell if it cuts the mustard.

Great writeup Paul! Of course Dynon is going to defend their units but it is impossible to compare the two because of the feature set differences and design intent.

The fact that the Dynon basically looses its mind on loss of pitot, and several reports of the display going blank, dark or flickering have caused great concern for me.

Everyone seems to be overlooking MGL but man I tell you if they deliver what they say they will, this market will be changing and changing fast to the builders benefit!

I think I'm glad I built my panel just before the glass revolution....

ahh, the beauty of a six pack

AlexPeterson said:

I think I'm glad I built my panel just before the glass revolution....

Click to expand...

nothing wrong with that.....as i am sure you know already.

Thanks Paul for the great post. After flying with my GRT system for two years I could not agree more. I do have the DigiTrak VSGV and while I agree that it is not a must I sure like two of the additional features it provides. One is the ability to set a target altitude and ascend or descend to it with your choise of vertical speed or air speed. That feature is especially handy in IFR to guard against busting thru the assigned altitude. The other is the coupled ILS or WAAS approach. I like to fly them by hand too but the capability of the auto pilot doing it (very accurately) is a nice option.

In response to George Jenson's panel lay-out and many others I see posted I would like to suggest the following: Many times I see dual screens placed like in an airliner panel, one on the left, one on the right. If you fly your RV as a single pilot, this important stuff belongs in front of your face, not the passengers. If you plan to fly IFR having the moving map on the far left that means the approach will be shown over there. Having to rotate your head that far to scan from the PFD to the map and HSI is vertigo inducing. My advice would be to establish an order of priority, e.g. 1) PFD, 2)map with horizontal awarenes data, 3) NAV and COM radio, etc. and attempt to place these items starting in the center of your field of vision in that order. The engine monitor can be on the right because it has alarms to draw your attention during an approach if needed.

Martin Sutter
building and flying RV's since 1988

Brantel said:

Everyone seems to be overlooking MGL but man I tell you if they deliver what they say they will, this market will be changing and changing fast to the builders benefit!

Click to expand...

If you will allow, I would like to respond without my MGL hat on.

Pilots like to compare EFIS. That's only natural. But it is difficult - perhaps outright impossible. Note that I am talking about the established players that have proven products out there and don't want to refer to "vaporware".

I'm going to make the bold statement that they are all the best and the worst and can do that at the same time. The reason is simple: These EFIS's are not created to a common design. They are different right from the word "go". The hardware is vastly different and so is the software. What you are seeing is the sum total of the thoughts and ideas that the people who designed these things have turned into reality.

You end up with a first approximation of the intended design - and from there it continues. Again - what comes out of it is what has been intended by the designers and the company that produces them as a whole.

GRT, Dynon, BMA, AFS and MGL are all capable of designing and producing the all singing and all dancing EFIS - right now. Would you want it ? Perhaps. Perhaps not.
For one thing - it may be a little bit more than you want to spend. Or it may be too big or too heavy. Most likely it will be much too complicated. Perhaps it will not be the most reliable in our typical rugged environments.

So, looking at what you can get right now - you have a lovely spread of fine hardware and software that has been meticulously designed by people with a passion for what they do - no matter what you need - you are likely to find something that gives you what you want at the price you want to pay. You have never had it so good.

Comparing product A with product B with the goal of deciding which is better is almost silly now. Rather - compare with the intention of which product is right for you and your particular needs - You may find that much more rewarding.

GRT's units are undoubtedly fine EFIS systems and I have yet to find somebody who is not happy with his. At the same time - Dynon has far more units in the field - that should tell us something, would you not agree ? Doubtless they must me doing something right.
These two products cannot be compared as they are made to do different things and within their design briefs both are excellent products.

Lastly - may I comment on failures as this has been mentioned. If you would like to buy an EFIS with a guarantee that it will never fail (or partially fail) no matter what - you live in the wrong universe. It's impossible - no matter how brilliant and good the design is. All you can do is MINIMISE failure. You cannot cancel it. Physics does not (yet) allow you to.
Failures of the display panel in particular (that is the actual LCD screen module) are reasonably common - mostly with a new product. This affects everybody, no exceptions. If you can point me to a manufacturer of LCD screens that makes sunlight readable displays with a zero lifetime failure rate - please do that, I would love to use those.

MGL hat on...

Having said all that - in my humble opinion (laced with a little bit of experience making around 20.000 electronic aircraft instruments in the last seven years) - you have a less than 0.25% chance of having a bad instrument (or part thereof) and this includes "Blow ups" due to incorrect installations. I don't think that is bad going and I bet other manufacturers will have similar figures to show.

Rainier
CEO MGL Avionics

Paul,

Excellent write-up! Thanks for taking the time.

As in all good research, you have done a great job of stating the assumptions and pointing out issues that may have biased your findings. I wish the "journalist" out there would do the same when they write their articles. I once heard that research had found that taking ibuprofen (Advil) negated the effects of the "one aspirin per day thearapy" many cardiologist prescribe. Later, I found that the Bayer had sponsored the research. That impacts the degree to which I believe in the validity of the research and should have been in the original report of the study.

In this case, you laid it all out there. It would have taken you a whole lot less time to just write up your conclusions. However, we have the information we need to assess for ourselves whether your findings apply to our situations. I also appluad your willingness to "put it out there". You have nothing to gain from doing this and knew you would be opening yourself up to possible criticism.

To me the two products are just aimed at different markets. Dynon has chosen to be the low price provider and is making decisions that are consistent with that strategy. GRT is a quality (features, reliability, robustness) differentiator and they are making decisions that are consistent with that strategy. Dynon has to be careful and not add costs to their product. Their market is more interested in the price. GRT has to be careful and not try to cut corners and sacrifice quality just to save costs. Their market is more interested in features, reliability, and robustness. Since Paul likes analogies... Walmart doesn't sell Rolexes and you can't get your hash browns scatterd, covered and smothered at Ruth's Chris Steakhouse.

Kudos to both companies for their hard work and success!

Dynon combos....

Ironflight said:

......
Multiple screens: Yes, to display a lot of information, you need to have a lot of screens. Dual head GRT is great. If I were building a DYnon system from scratch, I'd probably go dual D180's to get the real estate. The D180 and D10A is adequate, but the D180 is FAR easier to read (and the Superbrite option that Louise has is quite nice!)
.....
Paul

Click to expand...

Paul... perhaps Dynon Support could chime in here... but I believe the preferred dual screen Dynon approach would be a D180/D100 combination.

Dual screens, two EFIS, but only one engine monitor "processing box". Dual D180s would imply two sets of senders on the engine...

D180/D100 is is $800 less than Dual D180s - and that doesn't include the second set of probes...

gil A

Quality

apatti said:

Paul,

Excellent write-up! Thanks for taking the time.

...... Dynon has to be careful and not add costs to their product. Their market is more interested in the price. GRT has to be careful and not try to cut corners and sacrifice quality just to save costs. Their market is more interested in features, reliability, and robustness.......

Click to expand...

Is there any actual data to back this statement up?
Paul seemed about equal on this when you took a harness connector error out.

As another analogy - an 90's Toyota Corolla has a perceived better quality than a similar Chevy...

When in fact they were produced on the same US production line...

gil A - most modern electronics is way up there on the reliability scale once the first few hours have been run - the "infant mortality" failure factor...

That's why I don't eat at Ruth's Chris anymore!

apatti said:

...you can't get your hash browns scattered, covered and smothered at Ruth's Chris Steakhouse.

Click to expand...

That's why I don't eat at Ruth's Chris anymore! Bummer they don't have Waffle Houses in Chicago

Seriously, apatti has it right. The two companies are targeting different customers, although there is some overlap in the customers and capabilities. I've still got "steam gages" in my -8 but would like better engine monitoring, but I'm basically frugal so a Dynon D-10 will probably be added soon, and about 10 regular instruments removed (MAP, RPM, EGT, CHT, Volts, Fuel level (2), Oil Temp, Oil Pressure, and Fuel Pressure). If I ever decide to upgrade to more glass I may go more upscale with GRT or Aspen, or maybe stay on the low end with a D-10A.

The only reason I have not bought already is I want to see the units at Sun-N-Fun this year before making a final decision. Hopefully there will be some specials available there I can take advantage of too!

I gotta say, I am very comfortable with round dials for flight instruments!

Iron, an engineer that can WRITE. Scary! Thanks for taking the time. As always, your posts are full of good information. Have a great vacation.

Rainier Lamers said:

If you will allow, I would like to respond without my MGL hat on.

Pilots like to compare EFIS. That's only natural. But it is difficult - perhaps outright impossible.

I'm going to make the bold statement that they are all the best and the worst and can do that at the same time. The reason is simple: These EFIS's are not created to a common design. They are different right from the word "go".

GRT, Dynon, BMA, AFS and MGL are all capable of designing and producing the all singing and all dancing EFIS - right now. Would you want it ? Perhaps. Perhaps not.

So, looking at what you can get right now - you have a lovely spread of fine hardware and software that has been meticulously designed by people with a passion for what they do - no matter what you need - you are likely to find something that gives you what you want at the price you want to pay. You have never had it so good.

Comparing product A with product B with the goal of deciding which is better is almost silly now. Rather - compare with the intention of which product is right for you and your particular needs - You may find that much more rewarding.

These two products cannot be compared as they are made to do different things and within their design briefs both are excellent products.

Rainier
CEO MGL Avionics

Click to expand...

Rainier, well said.

Thanks for your intelligent/knowledged and unbiased analysis.

If I am lucky enough to be allowed to build another plane when the 10 is all done, your system will be high on my list of "Which EFIS??"

az_gila said:

Is there any actual data to back this statement up?
Paul seemed about equal on this when you took a harness connector error out.

Click to expand...

Gil,

I should have been more clear. By reliability and robustness, I was refering to the system design not the acutal units themselves. I should have limited my use of terms to robustness and left out reliability. I don't know of any evidence that suggests one unit is more reliable than the other. And you would have to be careful using anecdotal evidence here since Dynon has more units in the field (so I have heard and that is consistent with what I would expect). Paul also pointed this out in his post regarding reliability.

However, my understanding (based on non-refuted posts here on VAF) is that the GRT system can withstand more environmental variation (i.e. loss of airspeed information) and can still function properly. That makes the GRT system more robust.

I don't know the particulars of how all this works. If this is strictly a software issue, I would expect Dynon can at some point change this and still keep the cost of their system where it needs to be. However, if increasing the robustness of their design requires newer more expensive hardware, here is where I say Dynon has to be careful and continue to make decisions consistent with their chosen (and successful) business strategy.

az_gila said:

As another analogy - an 90's Toyota Corolla has a perceived better quality than a similar Chevy...

When in fact they were produced on the same US production line...

gil A - most modern electronics is way up there on the reliability scale once the first few hours have been run - the "infant mortality" failure factor...

Click to expand...

Gil,

This is an interesting point. Many years ago a Harvard business professor (David Garvin) conducted research on "what does the word quality mean?" He found that we routinely use 5 different definitions of the word "quality". An example of two of them: manufacturers usually refer to quality as "meets spec" while consumers (users) define quality as "fitness for use." These are completely different. An aircraft manufacturer could claim their aircraft climbs at 50 fpm and as long as it does that they can claim quality. However, most of us "users" would not view that as quality.

Garvin also identified 8 dimensions of quality - features, performance, conformance, reliability, durability, aesthics, serviceability, and (to your point) perceived quality. Certainly what we perceive the quality to be affects the actual quality of the product. I once reviewed a very interesting article for a conference on this topic. The article was entitled "Is Quality a Self-fulfilling Prophesy?" The gest of their empirically-based research was that people who purchased high-end cars were far more likely to take care of their vehicles (i.e. preventative maintenance, replace worn components sooner) than people who purchased low-end vehicles. Obviously, a car that is well-maintained will perform better than one that is not. This, of course, prepetuates the perceptions that the high-end cars have better quality.

Sorry, for getting off-topic here. I just find this sort of thing interesting. And, yes, that scares me!

Good Post Paul. I really don't know anything about other EFIS Systems but what I have read. A test hop in a RV6 with GRT's Systems inspired me to build an RV6, I just felt like I could immediately understand & assimulate the information displayed much better than steam guages. Hence, I have GRT Horizon 1 Systems.

In dealing with GRT, "THEY HAVE TREATED ME LIKE GOLD", the people there are the best of any company I have dealt with concerning all matters. For someone struggling with this decesion, it should be so easy.

Hummmmmm

ALL interesting posts.......However, I still do not know which efis I want..!!

Leaning towards the voyager.....if it ever materializes..!! cough, cough

Paul,
May I ask...what autopilot are you using?
Thanks.

GRT vs Dynon

Holy Moly Paul......how much did Greg pay you to write this??? I have dealt with Greg too and he is an outstanding guy, has great architecture, and speaks our language, but this post sure sounds like a commercial for GRT. I had a couple minor problems with my GRT and they were very helpful and responsive to my fix and would not hesitate to do business with them again. I've also had a Dynon, one of the first D10's, #7 I think, and never had any trouble at all. I flew it for 3 years and as far as I know it is still functioning perfectly. Does it have a moving map? of course not, it's a flight instrument. Having the capability to navigate around weather is possible with either system if equipped comparably - the Dynon system along with a G-396/496, which includes terrain - with just a couple clicks. The Dynon doesn't talk to your TruTrak yet, but big deal. Why is pushing one button so much easier to push than another? Having 2 Dynons and 2 ADC's is bad??? What's wrong with redundancy? I agree the way GRT builds their EFIS is good, probably as good as certified (since Greg designs architecture for certified systems - probably knows what he is doing), but I know many Dynon users (including me - I had Dynon and GRT in my first airplane), and don't see any difference in the reliability issues. Both companies have minor problems and they both are very good at addressing them. The primary difference as I see it is price. With GRT you get 'probably' certified technology at a homebuilt price. With Dynon you get 'possibly' the same technology, but at a distinct price advantage. No moving map with the expected interface, true, but you can buy it as a separate system, get the same functionality, provide another level of redundancy, and still save money. For many of us, that's important. Dynon says they will eventually own the entire panel and with the DSAB, they are on their way. I'm not trying to run a commercial for Dynon - just provide a little balance. I may have both in my new RV-8 (probably not), but both companies will be survivors and are committed to the homebuilt industry. Price is the noticeable difference, but they offer a totally different set of data, since Dynon is not a navigation instrument. When Dynon finally offers a NAV system, they will probably also offer an autopilot which will couple to all other Dynon systems in your panel via their digital avionics bus, and that is truly state of art, just like the newest certified systems. You are obviously pro GRT, I'll say I am pro Dynon just to have a v.s. point of view.

Scott

A few comments

Well, I guess this thread generated some interest while I was en route to my ski vacation!

Cytoxin: If you would have read the original post carefully, you'd find that the D10A has had two failures, and the D180 one. Dynon addressed both very promptly. As far as the cabling being "my fault", and your thought that I was lucky that Dynon didn't charge me, well, the cabling and connector with the problem was supplied by Dynon with the D10A two years ago. AS for troubleshooting, I was on the phone with Dynon repeatedly, they were very helpful, and we mutually chose our troubleshooting steps. There was no coercion on my part, and Dynon suggested trying different units. That is how troubleshooting works - methodically, until you find the problem.

Scott: I am very sorry that you feel that this was a GRT commercial. If you read the posts carefully, you will find that in the end, I point out that the two systems are for different purposes, and therefore are....different! I am a trained evaluator of flight systems. I tried to point out my assumptions and where I was coming from. As for accusing me of being paid by Greg, I find that insulting in the extreme. I don't know you, and I see that you are fairly new to the community, and I will give you a break and not assume that you are being paid by Dynon.

This post was presented because I had received NUMEROUS requests from people to contrast the two units, since I have had a chance to fly them both. For those that find the information useful, you're welcome. for those that don't, I hope that I have not offended you to badly.

Gill: You're absolutely right about using two large screen Dynons - you'd buy a D100 and D180 - I wasn't thinking at that level of detail when I posted, as I was headed out the door. And the superbrite Dynon is a great screen!

Paul

Fantastic Times

Paul,
Great post. I also fly dual GRT and many people have ask me about EFIS systems. I tend to think they do not totally understand the complete functionality of the GRT system as compared to the Dynon and Advanced systems. As you stated the Dynon (and in my opinion the Advanced system) are great to replace the 6 pack. Even though the Advanced system now has a moving map they are still working on adding many of the features included in the GRT.
I think your post will help a lot of builders get a basic understanding of the two different systems and their capabilities. GRT, Dynon and Advanced all have great systems. It is a fantastic time we live in when many of our home builts have better panels than many airliners that are still flying today!

GRT vs Dynon

Paul,
Wow,,,,I guess I really offended you. I didn't think you actually got paid by GRT, just trying to emphasize a point that the post sounded biased in my opinion. I should be more sensitive with the words I choose, and I'm sorry for not doing that. I wish I was getting paid by Dynon. Actually I wish I was getting paid by GRT, then I could afford their screen instead. I'm sorry Paul, I shouldn't use sarcasm with people I don't know. Take care.

Scott

Scott Hersha said:

Paul,
Wow,,,,I guess I really offended you. I didn't think you actually got paid by GRT, just trying to emphasize a point that the post sounded biased in my opinion. I should be more sensitive with the words I choose, and I'm sorry for not doing that. I wish I was getting paid by Dynon. Actually I wish I was getting paid by GRT, then I could afford their screen instead. I'm sorry Paul, I shouldn't use sarcasm with people I don't know. Take care.

Scott

Click to expand...

Thanks Scott - the internet is a funny place that way! Peace.

Paul

Roger mentioned Advanced Flight Systems, which is also on my interest list. Can anyone offer a "used 'em both" comparison with Dynon and/or GRT?

Paul, thank you for your post concerning the merits of these EFIS units. I am in the decision stage and leaning towards the GRT camp.

A post such as yours always sparks debate but THAT IS WHAT I NEED! Thanks again.

Dynon does not support third party autopilots and has said that they never will. I know they are developing their own autopilot but I must have a autopilot that is a separate system. I hate to think what would happen if the Glass goes belly up. With Dynon that will take out the A/P as well. Even with Blue mountain Avionics they support third party autopilots and produce there own system at the same time.
What good is a great EFIS if you can not integrate it with an Autopilot?
Dynon, GRT, Blue mountain, Advance.... They all have had there problems and all of them have boosted features that are not available now. Blue Mountain had a rocky start but now has a pretty solid performing EFIS and with the new software release they now have good autopilot system. Looks like they all have a pretty stable platform by reports I have read. To me it comes down to integration with current navigation radios and autopilots.
Simplicity is also a concern. I do not want to have 20 button presses in order to have my A/P fly a simple ILS approach.

Dan: I'll probably have input too late to help you. D10A and AFS 3400 are both in my panel which is nearing completion at Stein's. If you're still interested in a few months give me a holler. Bill

Thanks Bill. No problem waiting a bit. I'm gonna leave avionics until the very last.....things are happening so fast we might have a system with autoland by next year <g>

Poor assumption

jeff beckley said:

Dynon does not support third party autopilots and has said that they never will. I know they are developing their own autopilot but I must have a autopilot that is a separate system. I hate to think what would happen if the Glass goes belly up. With Dynon that will take out the A/P as well........

Click to expand...

That may be a bad assumption if you run a D180/D100 combination for redundancy. If the "smarts" that keep the autopilot sensible and the plane upright are in the EFIS, and if you have dual EFIS sources....

We need to see how Dynon does their autopilot.... too soon to make this assumption.

gil A

Although I show up as new in terms of number of posts and registration date, I have been a part of the RV community for more than 15 years and a lurker here since the beginning. I have become increasingly interested in ownership (yes I took the $______ ride) as opposed to being a casual viewer and would like to comment from that perspective.

I thank those people that are willing to comment on their experiences without fear of what other's may say. I thank the people that follow up on original posts and provide further information to those of us that for one reason on another, simply don't have access to their experiences.

I hope all of you appreciate what you are giving to the rest of us. There is no way to measure the value that is provided. Thanks.

az_gila said:

We need to see how Dynon does their autopilot.... too soon to make this assumption.

gil A

Click to expand...

It has been a while sense Dynon has updated us regarding there A/P. My point is while I am in the stage of panel planing for my next project I have to leave out Dynon as a contender. I have been burned in the past with promises of Gee Wis bang features only to be disappointed that it was all talk. A lot of time goes into a panel design. I do not want backup EFIS glass just so I can have redundancy of an autopilot. And I am sure not going to design a panel around future ware.
My frustration with Dynon is I want to incorporate there EFIS into a project I am working on now but I can not get past the fact that they will not support any autopilot that they do not make AND the fact that they do not have a autopilot. In my opinion this makes bad business sense. But what do I know?
I'm only the customer.
Just so I am not being misunderstood. I think Dynon has a great product. All four of the current front runners have a great product. GRT, Blue Mountain, Advance, Dynon.... None of them has what I think is the perfect system.

jeff beckley said:

All four of the current front runners have a great product. GRT, Blue Mountain, Advance, Dynon.... None of them has what I think is the perfect system.

Click to expand...

Hi Jeff,
Probably the most important thing I took away from Paul's great write-up is that you need to assess your mission and fit the equipment that meets your needs. It sounds like you're doing this.

I just wanted to mention that there are other EFIS vendors out there besides the 4 you mentioned. Even though some are brand new, they're worth considering.

I have over 12,000 hrs total flight time, only 150 in RV's. A significant amount of the 12k was autopilot on, perhaps 7K. When I fly the RV the last thing I want is an autopilot. I can't believe you guys do all this hands on to build your own airplane then want to be hands off to fly it.

As far as IFR goes no amount of cockpit equipment will make the RV an all weather flyer. IFR in a SE piston plane is a marginal game where you lose in ice, snow or power plant failure. Fly the RV as the man intended. If you want to push buttons save gas and money and use MS flight simulator.

........ wait........

ok...........


Nomex flight suit on......


ok, flame away.........