Jim Lewellyn
Well Known Member
I have owned a couple of airplanes, but never had one with an autopilot. So, my experience flying with one was limited to the rental spam cans I flew shortly after receiving my PPL. The S-cans I flew had nothing fancy, just altitude hold, and a heading bug for roll control.
A few years ago, I tore out the steam gauges and installed a GRT Sport HS in my RV6. At the time of the Sport install, GRT was not in the Autopilot servo business. Spring forward a couple of years and GRT now markets pitch and roll servos. I don't fly IFR, but on long cross country trips I wanted to have an AP to help reduce fatigue, and free up my brain a bit. So I decided to make the purchase.
Installation was really pretty simple. I searched the forums here on VAF and found a few threads on the under seat location for roll servo installation. For those that don't already know the GRT pitch and roll servos receive serial commands directly from the GRT EFIS which makes the wiring simple. I followed all of the GRT ground setup and test procedures, which are quite easy. Testing the roll servo on the ground was a no-brainer, but the setup/test procedure for the pitch servo left me unsure that I had the pitch servo direction of travel configured properly. I installed a circuit breaker switch that disconnects the power to the pitch and roll servos, so I decided I could safely test the pitch servo direction while flying at a safe altitude. Now that I have a better understanding of how to operate the AP from the EFIS, I can see a way that I could have proven the pitch servo direction on the ground.
First flight with the new AP equipment went extremely well. I climbed to a safe altitude and engaged the roll servo. I chose the heading bug as the NAV source and made some minor heading changes. The default roll tuning was a bit aggressive, but worked really well for a test hop. I worked my way up to 180 degree turns. Next, I engaged the pitch servo in altitude hold mode. It was moderately bumpy. When my altitude got below the AP set-point, the pitch servo nosed the plane down. Aw crud, it is backwards. I just shut it off and switched the direction in the EFIS configuration. Next time I tried it worked as it should.
Still on my first AP flight, I chose the heading bug for roll, and engaged the altitude hold and flew toward the extended center line of 26 at our local airport. The GRT EFIS has a synthetic approach (HITS) feature that I enabled for an approach to runway 26. Once the airplane intersects the runway heading, the AP is supposed to automatically couple the lateral and vertical AP to the HITS approach (when enabled). It worked exactly as advertised. What an awesome piece of technology! The vertical AP also allows the pilot to climb to a selected altitude, at a selected indicated airspeed, or descend at a selected FPM.
Initially, I found the roll tuning to be a bit more aggressive than required, especially in the bumps. The manual wasn't the best at explaining the proper tuning procedure, so a call to GRT was made. Ben gave me a few quick pointers, and from there tuning was simple and straight forward. I now have about 6 hours of flight time on the AP. I have yet to get it out on a cross country, but hopefully will very soon. This has been a great addition to my bird....Hope I don't forget how to hand fly
.....
A few years ago, I tore out the steam gauges and installed a GRT Sport HS in my RV6. At the time of the Sport install, GRT was not in the Autopilot servo business. Spring forward a couple of years and GRT now markets pitch and roll servos. I don't fly IFR, but on long cross country trips I wanted to have an AP to help reduce fatigue, and free up my brain a bit. So I decided to make the purchase.
Installation was really pretty simple. I searched the forums here on VAF and found a few threads on the under seat location for roll servo installation. For those that don't already know the GRT pitch and roll servos receive serial commands directly from the GRT EFIS which makes the wiring simple. I followed all of the GRT ground setup and test procedures, which are quite easy. Testing the roll servo on the ground was a no-brainer, but the setup/test procedure for the pitch servo left me unsure that I had the pitch servo direction of travel configured properly. I installed a circuit breaker switch that disconnects the power to the pitch and roll servos, so I decided I could safely test the pitch servo direction while flying at a safe altitude. Now that I have a better understanding of how to operate the AP from the EFIS, I can see a way that I could have proven the pitch servo direction on the ground.
First flight with the new AP equipment went extremely well. I climbed to a safe altitude and engaged the roll servo. I chose the heading bug as the NAV source and made some minor heading changes. The default roll tuning was a bit aggressive, but worked really well for a test hop. I worked my way up to 180 degree turns. Next, I engaged the pitch servo in altitude hold mode. It was moderately bumpy. When my altitude got below the AP set-point, the pitch servo nosed the plane down. Aw crud, it is backwards. I just shut it off and switched the direction in the EFIS configuration. Next time I tried it worked as it should.
Still on my first AP flight, I chose the heading bug for roll, and engaged the altitude hold and flew toward the extended center line of 26 at our local airport. The GRT EFIS has a synthetic approach (HITS) feature that I enabled for an approach to runway 26. Once the airplane intersects the runway heading, the AP is supposed to automatically couple the lateral and vertical AP to the HITS approach (when enabled). It worked exactly as advertised. What an awesome piece of technology! The vertical AP also allows the pilot to climb to a selected altitude, at a selected indicated airspeed, or descend at a selected FPM.
Initially, I found the roll tuning to be a bit more aggressive than required, especially in the bumps. The manual wasn't the best at explaining the proper tuning procedure, so a call to GRT was made. Ben gave me a few quick pointers, and from there tuning was simple and straight forward. I now have about 6 hours of flight time on the AP. I have yet to get it out on a cross country, but hopefully will very soon. This has been a great addition to my bird....Hope I don't forget how to hand fly
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