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ADD AP TO FINISHED RV4?

ansonfogel

I'm New Here
Greetings Oh VAF Wise Ones. I am purchasing a flying RV4 (and building a 10) and would like to add AP to the 4 - Tom Whelen built this 4 in 1992 wonderfully well - its all steam gauges, not even GPS. I'm debating a more full avionics UG, but ignoring that, assume I just want to add an older used GPS and 2 axis autopilot. How much structural headache is involved?
 
Greetings Oh VAF Wise Ones. I am purchasing a flying RV4 (and building a 10) and would like to add AP to the 4 - Tom Whelen built this 4 in 1992 wonderfully well - its all steam gauges, not even GPS. I'm debating a more full avionics UG, but ignoring that, assume I just want to add an older used GPS and 2 axis autopilot. How much structural headache is involved?

Very doable, the specifics will depend on the AP system chosen.

Do not be tempted to use any autopilot other than one built by one of the current vendors such as Trio, TruTrak, Dynon, etc. Old stuff like S-Tec, Navaid, etc will be more trouble than they are worth. If you do upgrade to an EFIS such as Dynon, et al, adding servos will give you a complete system.

Enjoy your new RV-4!
 
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Do it!

I installed a Trutrak Gemini into an early model 3.
Coupled with a Garmin GPS, the system was awesome.
Roll servo under the seat, pitch attached to bell crank.
Took some time and doing but well worth it. The Gemini is a great product.
 
The GRT Mini EFIS units will control servos, and it's a minimal panel modification. Maybe not as simple as a true track, but the cost is comparable and you end up with an upgrade path if you ever do get around to revamping your panel.

I'm not familar with Dynon or Garmin - I suspect there may be a similar path with their small backup EFIS systems.

Don
 
TruTrack Retrofit

I retro-fitted a TruTrack Vizon to my 20 year-old -4. Very straight forward modification. To simplify things, I did fabricate a custom set of angle brackets for the elevator bellcrank mount out of oversized stock (1 1/2" x 1 vs stock 1 x 1). This provided bigger "feet" and mitigated edge distance issues with the -4 rivets on the floor ribs. I mounted the roll servo under the forward, removable floor under the front seat. TruTrack has an excellent installation bracket for the roll servo and nice CAD drawings available. You can down-load the drawings to envision the installation. Stein did his usual first class work building the harness, and TruTrack product support is outstanding. You will have to do some control stick re-wiring, if you want full functionality (quick disconnect); unless you already have a spare wire available for this purpose.

While not strictly required, it's a lot easier to install everything if you pull all of the cockpit floors. De-riveting the aft floors and baggage compartment is quite simple and just about as fast as unscrewing them if you installed anchor nuts in lieu of avex rivets. Start in the baggage compartment and work forward, since you can unbolt the aft cockpit seatbelt mounts to gain access to all of the rivets. A 12" drill bit comes in handy for access. Do use some care drilling out rivets, as the rivets utilize the main fuselage longerons. Van's sells the rivets and any hardware you may need and you'll need some dome head and some countersunk, if airplane is built to plans. Also a good time to consider treating yourself to new harnesses, and a thorough inspection and lubrication of your flight control system, since you've got everything taken apart if you go this route. Hardware call-outs for this part of the flight control system are on Drawing 28.

I chose a stand-alone AP for redundancy, but if you already have an EFIS of some type, it's just as easy to utilize the same servo configuration and use one of those units to drive your auto-pilot.

Drop an email or PM if you'd like photos or have any questions if you decide to go the TruTrack route.

Good luck!

Vac
 
Another way to install roll servo is on wing tip rib ,reinforce as needed and fab a push pull tube to aileron bellcrank , there are times foot wells if installed can interfere with servo.
 
Just installed a used TT in an RV-4 - doable

The owner had purchased a used TT Digiflight GVSP--- I bought new install kits from TT, to fit the -4. Since I had installed previous TTs (RV-10, RV-8A, RV-6A), I was familiar with the general process. I put the -4 servos per TT plans. No problem, other than 77yr old pain on back, knees, and elbows.

I have it coupled to his new Garmin 660 GPS --- owner is thrilled with the setup.

Ron
 
Garmin

We put a G3X touch in my -4 to replace, well, everything that was there before.

Used garmin' servos and control head, now after some acro I can hit a button and fly home without touching anything else...it's almost wrong! If I was on a budget I would use a G5 and a 496 and still have an awesomely capable aircraft.

Roll servo under the foreword stick, pitch mounted to the bell crank. I needed help, but imagine most others could install no issue.
 
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Re: Garmin

Garmin offers so many options with their G3X system - if it's not too personal a question, would you be willing to share what you spent on the system, and which Garmin boxes you ended up installing?
 
Garmin offers so many options with their G3X system - if it's not too personal a question, would you be willing to share what you spent on the system, and which Garmin boxes you ended up installing?

Way more than I intended...

I have a spreadsheet I made I will email you tomorrow. Just this afternoon I did some acro, watched the AP fly a loc backcourse and then a ILS, and saw. The joker flying the unannounced 14 mile straight in final long before it even became a close encounter.

Necessary? Nope. Sure does expand the mission profile and reduce workload for me.
 
mratzburg: Tried to send you a spreadsheet with the equipment breakdown, but it won't let me email you through VAF. Feel free to PM me your Email if you want it.

Paul
 
Roll Servo

I have a Dyno with a pitch and roll servo. I installed the pitch servo using the Dynon install kit. No problem. I put the roll servo in the tunnel with an attachment to the stick bracket. Works perfectly. It is easy to get to and doesn't interfere with anything. The servo is mounted on a reinforcement plate to the left side of the center tunnel. Hope this helps.
 
I just want to add an older used GPS and 2 axis autopilot.

I did this in a flying RV-8 when it first became mine. The pitch servo went to the bell crank in the tail and the roll servo clamped onto the tube under the seat.

Like you, I just needed something basic for the GPS. For a year, I flew with a tiny hand-held hiking GPS that ran off 2 AA batteries :)

photo2-575x439.jpg

short blog post
 
I did the A/P install when I did the panel upgrade to the GRT HX about a month ago. It was straight forward and an excellent addition. If there is someone in your area that has had experience with the servo installs, you could save a significant amount of time. It took about me about a week 25 to 30 hours to complete. A third f the time was thinking about where and how to do the roll servo install to keep it out of the way.
 
Trio A/P

I put in a Trio Pro Pilot, roll servo in left wing tip and pitch on elevator bell crank. Trio mounting kit and it was a breeze. Hardest part was getting the wiring from the servos to the panel.
 
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