RV10 IFR Panel Theory

As I was running my checklist of features I wanted in a panel, I formed this small list of items that I required of my panel. Some of these items may not fit your needs or style, but I may be able to give you some things to think about. I'll pick these lines apart below to give more detail.

A FULL IFR platform that includes redundancy in most systems
A Split electrical bus ("essential bus") to provide an easy way to go to minimum power draw.
A 2nd anternator and *small* battery for redundant power due to semi-reliance on electronic ignition. (Lightspeed Plasma III)
A moving-map GPS approved for Enroute and Terminal operations able to legally fly most all approaches, including WAAS
A 2 axis autopilot with Altitude Hold capability, that can track NAV, GPS, HDG, ILS+Glideslope, WAAS Vnav slope, and does GPSS
Dual COM's and preferrably dual NAV's. (One NAV would be OK if necessary)
A secondary GPS, even if it's just a good handheld (The Chelton provides an internal WAAS receiver as well as the GNS480)
A Multi-Function Display (MFD) capable of Doppler Weather Radar and TAF/METAR Datalinks and Traffic capability
Redundant Attitude, Airspeed, and Altitude, and Heading Indicators...at low cost
5 place intercom with split-com function so Pilot and Co-Pilot can transmit on separate radios **1 place is for video cam
Audio inputs for Stereo Music, DVD players, and Cell phones, with the ability to have separate music Front and Rear
Issues with other equipment

A Full IFR Platform
If you're building an IFR plane, but you're not yet IFR-certified, please believe me on one thing.....you NEED to go at least start your IFR training before you do anything regarding picking items for your panel. This is not at all meant to offend anyone, but you cannot possibly understand your needs for IFR, or your equipment placement preferences, or critical functions, if you don't go at least start working on the rating. I would add to this that if you haven't had some actual time in IMC, not just hood time, that you will benefit greatly from that too. So, if this applies to you, go spend $1000 and hire an instructor for a few hours of instruction and make them take you out when you've got some nice IFR weather. It's well worth it, and in my case I find it some of the most fun, challenging, and exciting flying that you can do.

First, what is a FULL IFR platform? By "full IFR" I mean a panel that includes all the equipment you need to operate IFR both enroute and terminal, and able to fly most any listed approaches. Some people would call a plane with just dual COM's, a single NAV, and a little more equipment an "IFR panel"....you see this all the time with Cessna 152's used for training. This is not what I'm at all shooting for. When I mean "full IFR", I'm looking much further out for functionality. There are still many GPS's out there that are only legal for enroute operations, and contain no approach information. This does not meet my requirements. I also would not consider a panel to be "full IFR" unless you have at least one NAV receiver onboard. Debate the value of a NAV (VOR and Localizer) receiver all you want, but if you don't have one today in 2005, you're handicapped greatly from flying many approaches, and currently you would be unable to fly to the lowest possible minimums. You NEED at least one Nav/Com. An ADF? No, you can skip that. A DME? Skip that too. What about DUAL Nav/Com's? For IFR flying, you will benefit GREATLY from dual COM's, and there's a lot to be said about dual NAV receivers. You'll find that below.

A Split electrical bus (E-Bus)

In building an IFR panel, for an all-electric plane (the most likely case for 95% of all RV-10 builders), there are concerns in the area of electrical power should the alternator die. If you have at least one Mag, or if you have P-Mag's (New electronic ignition in a powered mag format), then at least your engine will keep running, but what about your instruments? This is where creative power distribution circuitry can really help. If you follow the Aeroelectric List (another Matronics email group), you'll find a lot of great info on designing your power system. Much of the info is also available on the Aeroelectric Page, with the most valuable information being contained in Bob Knuckoll's "Z-Diagrams". The Z-diagrams got their name because they are in appendix Z from Bob's Aeroelectric book, which is a must-buy for any airplane builder. There are options for systems that encompass the entire range of electrical designs, such as dual-battery, dual-alternator or other designs. One of the more important concepts is the "E-Bus". The E-Bus (Essential Bus, or Endurance Bus) is a separate bus, powered by an optional alternate feed path, that allows you the benefit during an alternator-out situation of shutting off the master power, turning on power to the E-Bus, and automatically trimming down your electrical loads to a minimum-draw situation...giving you the most life possible out of your battery. In my own personal power plan, I have a design that allows for a lot of functionality, using dual-alternators, dual-batteries, and an E-Bus, Avionics Bus, and Main Bus. Sounds complicated, but it's not too much more complicated than many of the others. The benefit is that I can retain the "Avionics Master" that is so often disputed on the Aeroelectric List, allowing me to turn off my avionics...and just my avionics with one switch, and still have an E-Bus that goes to minimum power...and also having the avionics master functionality. In my plan, I'll be able to power my Chelton screens with a smaller Aux. Battery during engine start, which will allow me to get my temperatures, pressures, and RPM, and not have to worry about my systems being rebooted when the starter draws tons of Amperage and lowers the voltage of my electrical system. Also, since I'll have a Lightspeed ignition until the P-Mag's are available in 6-cylinder models, I'll be able to power my ignition off from that same bus during engine start, which will help prevent the starter from being damaged due to kickback from the same low system voltage condition.

A 2nd Alternator and Small Battery

Continuing the discussing above, I plan to add a 2nd alternator to my system. I don't currently know if I'll add this initially, as there are fewer options this year, and more coming next year, at probably a much lower price. I figure that my first year I'll likely not fly hard IFR for a while until I both have the time flown off, and become proficient with my panel, so it might be a good time to sit back and watch the alternator market. For the small battery, I'm still deciding what to use, but at minimum, it will be a small 12V 12Ah sealed battery, such as what is used in a computer UPS. I might have to move up to a 15 or 20Ah battery though, depending on the overall draw of my critical equipment.....(Two Chelton screens, my SL-30, my audio panel and my electronic ignition) My GNS-480 and other stuff can be left off during those types of emergencies.

A WAAS capable GPS for Enroute and Terminal Ops

This is where things start to get a little confusing.... First of all, some people claim WAAS capability isn't a big deal because there are few WAAS approaches, but, given the relative cost to the government of these approaches, there is little doubt that the future is in WAAS, at least over ILS. So yes, I consider WAAS capability to be a big deal. The Chelton system does include it's own WAAS enabled GPS, so WAAS approaches can be flown with it. There has been much debate though on wether or not TSO'd equipment is required. Read THIS article for some good perspective on this. If you decide that you need TSO'd equipment, then your options become limited. You can choose from the Garmin GNS-480 (previously known as the Apollo CNX-80) or the FreeFlight remote mount GPS. From my most recent bit of info on these, the FreeFlight actually replaces the GPS signalling in the Chelton, and provides better integration to get everything you'd need for doing WAAS legal approaches. It's also cheaper, being in the neighborhood of $5,000. Seeing as you get incredible functionality with this, it's a great option. The other option is the GNS-480, which doesn't integrate nearly as much into the Chelton system, but, has it's own benefits. The benefits are things like....having a second NAV receiver, having a second moving map display, having a separate piece of gear that can fly your approaches and feed your autopilot, and things like that. Unfortunately,
this option will cost you about $9000....or more, if you consider the need for an AIRINC to serial converter....which is needed. (Although you'll need that for doing Mode S traffic too, so it's not necessarily ALL extra cost just for the 480) In my panel, I chose the Garmin GNS-480, but, to be blatantly honest about it, I consider that to be my "Com2/Nav2" relegated to reletive non-use, and it's probably the LEAST valuable item in terms of flight use that I have purchased. If I needed to save a few thousand bucks, you can definitely bet that I'd be swapping my SL-30/GNS-480 combo for an SL-30/SL-30 or SL-30/SL-40 combo. So, what about some of the other GPS's, or GPS/COM's? Well, if you get a Chelton system, you'll find that you really don't need much else in the way of GPS....it has it all. But, if you get something else, make sure you're getting full Enroute and Terminal capability with full approach capability.

A Full-Featured 2-axis Autopilot

Here's where a panel's best features come out. A good, integrated 2 or more Axis autopilot can literally be a life-saver. From the reputation TruTrak has earned, it is really the only one I'd trust to fly my plane. I do like S-Tec too, but in an experimental, why spend that money for something that won't work as good? The TruTrak will integrate into my Chelton system and allow full lateral and vertical guidance for approaches, including tracking both GPS, and NAV/ILS/Glideslope signals. The model of Autopilot I chose is the TruTrak DigiFlight II VSGV. ** As a side note, it should be noted for 100% accuracy sake that currently shipping is only the VSG model...the VSGV (vertical guidance) is not currently available...although it absolutely IS functional. Chelton has been flying vertical guidance with their EFIS using beta software from TruTrak, which should be released very shortly...within a couple months of OSH2005 from what I've heard. After the software is realeased, my TruTrak has to go back in for a software upgrade that will make it a VSGV. It should be also noted that this capability problem is NOT a Chelton problem, as they are currently sending the properly formatted commands to the autopilot...it's just that the autopilot doesn't use them. They all assure me that since they actually have this system flying that it will be a very short time and all will be well with the world of TruTrak. One other note about the VSGV is that it does NOT contain the standard Left/Right/Up/Down +/- 150mv autopilot signalling capabilities....so it cannot be directly driven to follow a glideslope of, say, the SL-30. The Chelton system, in my case, allows the SL-30 to feed it the data, it processes the data, and sends it digitally to the autopilot....which is another way that the Chelton system actually saves me money. If you didn't have a Chelton, you really NEED to go buy up to the TruTrak Sorcerer autopilot, which is the top of the line at TruTrak, and costs at least $3,000 more than the DigiFlight II VSGV.

Just to make note of it here, when I last checked with Blue Mountain, they not only did NOT have approach data in their system, but they did NOT have the ability to fly an approach fed to it by another radio, such as the GNS-480, and even worse, their autopilot (which had/has been known for it's hunting and lack of stability) was not able to track a real glideslope or NAV signal from a Nav/Com.....so it is very limited at best, and in my opinion is exactly NOT what you would want if you were building an IFR panel. If you're looking at them, first, learn the questions to ask, and then, ask the questions...and educated buyer will be a more happy buyer.

Dual COM's and Preferably Dual NAV's

With Dual COM's, you will be able to listen on one frequency to ATC, while getting reports from Flightwatch, or contacting UNICOM, or many other things on the 2nd COM. Yes, the SL-30 and SL-40 have the ability to monitor the alternate frequency, so this is VERY close in functionality, but it isn't the best you can do. With the right audio panel (in my case, the PS Engineering 8000), you can actual do "split COM" where the Pilot can simultaneously talk to ATC on COM1, and the co-pilot can use the 2nd COM on any frequency they wish. This will sometimes prove to be a very nice feature. Also, having dual COM's means you'll have 4 loaded frequencies at any one time. I frequently load ATIS into COM2, and my current ATC frequency into COM1 ACTIVE position, and something like the CTAF or Tower frequency into the COM1 STANDBY position. Then when I get the handoff, it's a one-button push, but I still have my ATIS loaded on the 2nd COM. When you also look at it from a redundancy stanpoint, if you wired your BUS's "right", your COM1 and COM2 won't be on the same BUS, and the loss of one COM or even everything on one bus won't cut your communication possibility. I won't even carry a handheld, because with dual-bus's, and dual-COM's, the chance of requiring a handheld is VERY small.

How about Dual NAV's? This one gets a little harder. Without GPS, there were absolute times when you would either need to do a lot of frequency changing and OBS twisting if you only had one NAV and needed to triangulate your position using a single NAV radio. Dual NAV's make it easy in that you can tune in 2 VOR's separately and find that fix easily. And, in IFR flying, you need to know or sometimes even report, your crossing of a fix that will need to be derived from 2 VOR's (if you don't have GPS). So, I personally decided to have 2 NAV radios. With my panel though, the chance I'll ever need that 2nd NAV is pretty slim, so it may be that a NAV/COM, and a single COM (SL-30 and SL-40) will be plenty for a person. I have personally been in a situation where GPS coverage was lost for 10-15 minutes (and I was VFR at the time), and I can tell you that if you've been flying direct on a long X/C flight, you start to feel uncomfortable....so you need at least one NAV, and 2 prepares you even better. Cost-wise, there's a lot of options too. A SL-30 + GNS-480 pair like I got, will likely run you around $12,000 (all these prices I will list will be rough), while an SL-30 + SL-40 combo will run you more like $4600-4800.....a BIG cost savings. You may start to become very interested in my Chelton page once you start to see some of the actual cost SAVINGS you can accomplish with such a system.

A secondary or redundant GPS

In my panel, I wanted to have at least one GPS, which I have in my Chelton system. I also wanted to have a secondary GPS, which I have in my GNS-480. This is probably overkill for most people (including myself). I feel a good, color handheld, like the AvMap Mk-IV, or the Garmin 396, would make a great secondary GPS. The fact that my GNS-480 is also my secondary Nav/Com, and is able to legally do approaches, control my autopilot, and many other functions, is just added benefit, but it comes at added cost.

A Multi-Function Display (MFD)

In today's panels, a MFD is pretty much a necessity if you're going to be trying to add function such as weather (WSI or XM), traffic, or a good, large, highly readable Map. Yes, some GPS/Com's can do some of this on-screen, but man you'll be suffering when it comes to visual quality. Another note about MFD's is that yes, you can get this functionality by buying things like a Garmin 396, but you won't get the INTEGRATION that a MFD gives you. Adding an Avidyne EX500, an MX-20, or a Chelton system will give you MUCH better integration of your systems. In my original panel design, I had a GNS-480 paired with a MX-20, and 3 Grand Rapids screens. This was a great little system, with lots of ways to view data, and a fair amount of integration. I did, however, find that it was expensive. The MFD was costly, and then if you added the expanded I/O necessary for traffic integration, it got more pricey, and if you wanted weather, you had the GDL-69 (I think that's right) that cost a bunch more, and it totaled up to be a pretty expensive system. When I went with the Chelton system, I found that by changing from 3 GRT screens to 3 Chelton screens, I could toss out the MX-20 and keep pretty much all of my functionality but in less space and in a more integrated package. Integration is key when flying behind sophisticated systems like these. At present, my least integrated component is my GNS-480, which will make it complicated and clumsy to use, which is why it's on the top of my "toss out" list if I were on a tight budget.

Redundant Attitude, Airspeed, Altimeter and Heading

This is easy for me. I preferred, not having any EFIS time, to having something VERY basic, that anyone could read quickly and understand. So in my panel, I planned to use standard round gauges as backup. Well, I guess they're not completely standard....I have the TruTrak ADI. The ADI will give you pitch and roll information, like an attitude indicator, but it will also give you a digital heading readout. It also will include a battery backup so that if I lose all power completely, I can still fly by the ADI for a while. The only flaw I can see in my round instruments is that the small ones are often more expensive, and not as easy to read or have less resolution than the big ones....especially the single-armed altimeter. Another option would be to add a cheap display like a small Dynon as a backup. I don't think this would be such a bad instrument as a backup, but personally I just prefer round instruments for that purpose. One other thing to consider is that the Dynon, is electrical, even though yes, it does have a backup battery option.....and, it will be more complex, since it requires slightly more wiring into the plane to make it all work.

5 Place Intercom and Audio Panel with Split-COM

The 5 place intercom comes from an unusual requirement. I want to be able to videotape flights from inside the plane, and also record the audio from the intercom. So, I will wire my plane for 5 jacks. To prevent impedance issues, I will use individual jacks to 5 of the 6 outputs. Another thing I wanted out of my intercom was the Split-COM function, allowing the co-pilot to be able to communicate on COM2 while I communicated on COM1. This should be very handy in the right situation. I also required Pilot Isolate...one of the most valuable options on the audio panel, and the ability to pump in stereo music...with separate music front and rear. Speaking of Front and Rear, there's another add-on that I'll put on my intercom. Often when flying with the family, my wife is in the back, although when I isolate the communication to "CREW", I want her to be on with me so we can talk without disturbing the kids. To do this, currently she has to plug her headset into an extension so she can sit in back and plug into the front jacks. In the RV-10, I'm going to wire in a switch so that I can switch my Co-pilot location from front Right, to rear Right. Then there will be no extension cables necessary.

Audio inputs for Music, Movies, and Phones

Continuing the above, I plan to put in a portable DVD player for passenger entertainment, and I already carry an Archos FM radio/MP3 player (like an IPOD). I won't go with a fixed DVD unit because I want to pull it out into the car for travel too, and most of the movies we watch are compressed into VideoCD files that are stored on a hard drive. So, I'll be looking for a good portable 40+Gb music playing hard drive based unit over time, or maybe just use a laptop with remote screens for now. A phone input is also a requirement of mine. You may not need it often, but only a week ago I had to call my wife for a quick weather update because I was flying towards some nasty stuff and wanted to hear how it was at the destination. Legal or not, when something big comes up, I want to be able to plug in and dial without the engine noise. Also, for ground use, it would be great for obtaining takeoff clearance for IFR flights using an GCO. (Radio to phone system)

Issues with other Equipment

I've got a 2nd page started with info on why I chose the Chelton system and the radios that I did, but here I'd like to tell you a little about why I didn't choose certain items. Some of this info. may be or become outdated as time goes on, but it was all my understanding at the time I learned what I did.
It's all opinion, so if you chose this stuff, don't take offense. Also, keep in perspective that I'm looking only for good IFR equipment. If you're building a VFR panel, most everything on this page wouldn't apply to you.

Blue Mountain: Originally I had thought the Blue Mountain was the way to go. When you look at the cool display on the EFIS One, or EFIS Sport, they were extremely cool and smooth looking....like with the terrain depiction on the horizon display. I went to OSH 2004 and after looking at the sport, I thought I had found what I wanted. Too bad that my dreams were trashed when I spoke with them. Their sales people were arrogant, which never helps, but even though they had some cool features, I found things also lacking. For instance, their GPS does not include approach information, and you are not able to load an approach in the built-in GPS. So, you need to start thinking of adding another box to fly your approach by. Oh well, toss in the GNS-480 and you have it, right? Well, kind of. The 480 could couple to a TruTrak and fly an approach, but they said the 480 could not be hooked to the BMA autopilot to fly an approach including vertical guidance. I had a friend with me who flies for the airlines to listen in to a funny exchange....I asked if you could fly using a 480 and fly the GPS "glideslope" and the reply was "Why would you want to do that?". At that point, I became suspicious of what kinds of other limitations the system would suffer, and how they would deal with them. I REALLY wanted a system that I could TRUST while IFR to fly the plane, including the glideslope, when things got real tough. Single-pilot IFR is tough stuff....maybe not when you're at 800' ceilings and in smooth, wet clouds, but I was lucky enough to basically have my life saved by a very experienced pilot during my instrument training, when flying an ILS in very turbulent weather, with 300' ceilings. If it weren't for his solid hand on the other yoke to prevent my improper inputs, and his cool head to try to calm me down, I'm sure that it would have been my last approach. That was during the first few hours of Instrument training, and I learned full well that the "Leans", and "Spatial disorientation" are absolutely real....and I gained a healthy respect for IFR Flight. Since then, I have gained experience and that same situation would be less traumatic....but my point is, you're literally taking yours, and your family's life into your hands when you venture out IFR (or even VFR for that matter), so you need equipment you can trust....and I'm not ready to trust BMA. They put out lots of updates, but there are always reports of funky quirks too. From the things I hear, I wouldn't necessarily call their stuff stable. Also, although
I think their Sport unit would make a nice backup unit, I just don't think you'd find that most of their stuff will completely integrate into your other equipment as you'd like.

Dynon: Dynon makes a very decent EFIS/EIS combo at a great price. What I wouldn't call it though, is an integrated unit with anything else, and even they themselves will say it's not for IFR use. There are interesting flaws that come about when you dive into the system a bit...one real notable one is the failure mode if you lose airpseed input. Dig some archives, and you will find that the attitude display will become unreliable if you lose airspeed input. As it turns out, many of the EFIS systems have similar problems, so investigate that issue thoroughly. The Dynon pitot is also said by them to be "not for IFR use". Well, in that case, it could just be a liability statement, but still....if you want to fly IFR, perhaps you should look into equipment that the manufacturer would be willing to stand behind for IFR use. The Dynon would make a good backup gauge, for those inclined. I find the small version pretty small to use as a main display. They cram a lot of stuff on those tiny screens, and after having flown right-seat, looking at a left-seat Dynon, I don't think I could go with one. The sun washed out the screen for me, which didn't help either, but the text was not very readable from my angle either. Like I said though, for backup, it might be great....for me, I'd rather have round gauges.

GRT: The GRT stuff is actually looking very good these days.