[nturner]

I am interested in other builders/pilots views on installing and using either a vacuum system with artificial horizon etc or a Dynon type system.

What do you prefer to use and why?

I am building an RV7A and have been thinking about which way to go and would appreciate other peoples views. I know there may be a cost difference but what are the advantages/disadvantages etc.

 

[painless]

I'll be the first to chime in. Let me preface this by saying that I have not gotten my 6A flying yet (REAL close), so take that into consideration.......

I went with a Dynon (EFIS) for several reasons. First was ease of installation. No vacuum lines to install. Also, no need to service/replace a vacuum pump *when* it fails.

Then there is the weight consideration. One EFIS unit replaces at least 4 instruments (ASI, VSI, Articial Horizon, ALT) which add up in weight. In the case of the Dynon, you also enjoy a cost savings.

Panel space is also saved by consolidating several instruments into one.

I also like the fact that I can look at one spot on my panel to get all the flight info I need.

I have the backup battery in my Dynon in case the master goes Tango Uniform.

I guess the only thing I am concerned with is the fact that it is an electronic device and electronic devices, especially ones that are driven by computer chips, can go nutso at times. That is why I have a backup ALT and an LRI. To be fair to the EFIS units out there, however, they seem to be getting the gremlins worked out of them quite well by the various manufacturers.

One last thing I have not mentioned. EFIS units are cool as all getout, but that should not be the driving force for making your decision.

Regards,

 

[Ironflight]

Other advantages...

In the 22 years I flew my Grumman (much of it IFR) I went through 4 vacumm pumps. Fortunately, I never lost one in IMC, but if I had, I had a backup electric HSI, which makes partial panel much simpler.

With my GRT EFIS, I have a full electronic system with no moving parts to break, and save all the weight of a vacumm system. Yes, I still have a backup ASI and altimeter, but they are not heavy. Leaving out the vacumm pump leaves a spot on the engine to install an 8 Amp standby alternator, thereby giving you additional redundancy. Overall, an electronic platform with backup power gives you a much more robust system than vacumm (in my opinion), and the software reliability is rapidly becoming a non-issue.

Paul

 

[dan]

Dynon=good

656 hours on the Dynon in my all-electric-on-a-budget RV-7. Great stuff!

Early on, my EFIS-D10 had "the leans" -- it would indicate a 5-degree bank under certain conditions. I didn't have full confidence in it for obvious reasons. In an early software revision, I saw one quick momentary pitch error. With software updates Dynon Avionics resolved these issues in my installation, and I have gained the confidence I need since then.

I can get it to go gray and evoke an "Attitude Indeterminate" warning when I do loops, cubans, and sometimes during spins.

I have had one "Temperature Out of Spec" gray warning in the summer in 109F heat. This happened when I flipped the master on when I went to start the plane up. It had been sitting out in the sun & heat for several hours. By the time I hit the runup area (before taking off), enough air had circulated that it cooled down and the warning went away.

With my EFIS-D10 I have made 27 instrument approaches, 14.8 hours actual instrument, 2.5 hours simulated instrument. I don't fly a lot of IFR, but I do trust the Dynon.

I have had one vacuum system failure in a previous airplane.

My personal feeling about "all electric" is that with a modern, reliable EFIS, a decent autopilot, and a well-designed electrical system, I am in way better shape than if I relied on a vacuum system. This is obviously subjective. Do yourself a favor and read Bob Nuckolls' "AeroElectric Connection" book. Even if you're a staunch "vacuum conservative" and don't end up agreeing with everything he writes about, it's a great read with lots of useful information.

)_( Dan
RV-7 N714D
http://www.rvproject.com

 

[osxuser]

I'm a bit of a redundancy freak, so I was planning on a Vacuum attitude indicator with a BMA EFIS Lite mounted in the "DG" position of the T and used as an HSI most of the time, switching to an AI in case of vac pump failure. I was also planning on using the Sigmatek Apex piston pump to prevent said failure...

 

[mark manda]

Too cool

Only thing that has worked right out of the box and kept on working.

 

[painless]

How was the transition?

Dan C:

How was it for you converting from analog guages to going digital? Did it take some getting used to for you?

Regards,

 

[dan]

Reliance on steam gauges

How was it for you converting from analog guages to going digital? Did it take some getting used to for you?

Converting? Who converted? Just kidding, but I do still rely heavily on the steam gauges -- ASI, altimeter, and VSI. The Dynon for me, while it does have everything in one, is all about ATTITUDE & HEADING. For the rest, I prefer needles & dials. Just the way my mind works.

Jeez, I really should have mentioned that in my first post. While I do think these new EFISs are all that and a bag of chips, I personally would not be comfortable flying IFR without analog backup for airspeed & altitude.

)_( Dan
RV-7 N714D
http://www.rvproject.com

 

[mgomez]

The steam gauges aint' cheap either

I just did a cost comparison for the vacuum gyro panel and a dual-GRT-plus EIS-system. The EFIS panel cost $3000 more...less of a difference than I expected. The reason is that it replaces a lot more than just gyros.

For example, if you have to buy Garmin's CDIs for your VOR/ILS, that's $1500 apiece (give or take).

To me, the biggest reason to shed the vacuum system is that I want that accessory pad for a standby alternator.

As some of you know, I'm the guy that Bob Nuckoll's mentions in his chapter on reliability...he quotes my "Never Again" article from 1999. So a backup alternator and split busses is one of the "desirements" for my RV-7.

 

[jcoloccia]

I won't speak as a pilot because nearly everyone on this board has more flight, building and aircraft maintenance experience than I do. I will speak as an engineer, though

There's only one good reason I can come up with for a pilot to own a vacuum: cleaning off the workbench. I'd go on, but Aeroelectric Connection says it all. From a system reliability and flight safety standpoint, Nuckolls hits the nail right on the head.

All electric may not be "better"...that's opinion and up to the individual to judge. It IS more reliable, though. For example, the turn coordinator is, strictly speaking, more reliable than the attitude indicator. That's because it's a brutally simple device with almost no moving parts. In spite of this, though, my backup for the GRT (or whatever EFIS I eventually buy), will be an electric attitude indicator. Less reliable, but better in my opinion.

In the long run, the price of all electric may actually be cheaper when you factor in cost of ownership. Maybe not. With electric, you have to do scheduled battery maintenance if you intend on doing regular IMC. I don't know how those numbers would work out, and a lot of it would end up being luck of the draw, I think.

As usual, my totally uninformed but highly opinionated $.02

 

[penguin]

You could also use a Trutrak attitude indicator, combined with autopilot head, as yor back-up attitude source - I believe they can be fitted with their own battery & GPS (for heading) for complete redundancy.

Pete

BTW - there's no such thing as software reliability. It either works or does not. For a given set of inputs a piece of software will always react in the same way.

 

[rv9aviator]

Trutrak ADI

I have already bought a Trutrak ADI with Auto pilot, with altitude hold. I haven't decided what glass panel to buy yet but The ADI will be front and center.
Jim Wright Rv-9A 90919 Arkansas

 

[rv8ch]

Software reliability

BTW - there's no such thing as software reliability. It either works or does not. For a given
set of inputs a piece of software will always react in the same way.

True, but if the device has any kind of Real Time Clock, then every tick of the clock creates a
potentially totally new world for the software. Not to mention all the other environmental changes,
like turning to 031 degrees while taxiing, instead of 030 degrees.

Of course, software can be tested to ensure that these changes don't affect
anything else, but who knows what these EFIS guys are putting in their boxes?
That said, I'll be relying on several computers to keep me from having to flap
my arms to stay aloft.

 

[Ironflight]

Software...

BTW - there's no such thing as software reliability. It either works or does not. For a given set of inputs a piece of software will always react in the same way.[/QUOTE]


Your right, but the problem with a complex system is every getting the same set of inputs twice....I doubt that there are many flight software packages as heavily tested as what we run in the Shuttle, yet we STILL run into glitches now and again (rarely, of course, but I've had my heart stop once or twice on console ).