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  #1  
Old 03-17-2017, 04:23 PM
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Tony_T Tony_T is offline
 
Join Date: Dec 2008
Location: Seattle, WA
Posts: 1,114
Default Fun With SVT Expert AP Mode

I'd like to tell you about some RV-12 fun with VNAV. Although I am instrument rated, I’m not current and would certainly not try this for real. It’s just for fun. As a matter of fact, fun is the reason I built my RV-12. I had no plans to ever fly it in IMC, or to the NW Territories or even to Oshkosh. I like my comforts, and am a bit too old for that all day in the cockpit, or busy IFR stuff, I’ll be eligible for the UFO’s two years from now.

But, I love the neat IFR pilot stuff and one of the main reasons I spent the time and money last winter to upgrade my D-180 panel to SVT was all that eye candy, and capability, on the screen. For fun only, of course .

So, yesterday I launched out of my home aerodrome (KPWT) to try out the SV autopilot on a NAV to an extended runway centerline, and descend on a VNAV profile to the runway, on autopilot. This airport has an ILS and also a VNAV approach to RWY 20. The approach angle is 3.0°. In checking the default SV settings I found the VNAV glide slope angle set to 2.5°, so I had to change that. I also changed the height above the runway from 100’ default to 50’. I was not too sure what I was doing here.

Once airborne and about 15 miles out, I set the ALT target to 2500’ in order to fly to the IAF (WUMOX) and intercept the glide slope from below and instructed the autopilot to start down to 2500’ and fly a HDG of 152° to intercept the GPS extended centerline outside of WUOMOX. During the descent I armed VNAV. Then I noticed that the ALT HOLD was 2700 and the target altitude was now 491’. At the time I was not too sure what had happened.

Now I realize that arming VNAV activates ALT HOLD at the point where you pushed the button. OK, I armed VNAV while passing through 2700’; that explains that. I also could not figure out why my target altitude was 491’, a seemingly peculiar number. Back on the ground doing the debrief, I see now that the Touch Down Zone Elevation is 441’ and with my map options set to 50’ above the runway the total is exactly 491’. It’s nice when you see how everything adds up!

In this screenshot the AP has turned her onto the GPS track line and approaching WUMOX the blue “angle” tick mark and the magenta “VS’ tick mark are coming together as they should be. There is a rain squall approaching the airport at about 19 knots. There are a couple of traffic targets that could become factors.


Passing the IAF the VNAV activates in the top bar, she points the nose down and the VS and tick marks are right together and we’re headed down to the target altitude of 491’ (50’ AGL) over the TDZ....it can’t be legal to be having this much fun!



The pilot does need to control airspeed with the flaps and throttle…no auto-throttle — dang.

After this I goofed up trying to take a screenshot when the runway came into view on the synthetic vision and I touched the GO AROUND button and Chatty Patty told me to go around. I didn’t know what the autopilot was going to do and getting close to the ground so I pushed the auto pilot disconnect. I beat the rain squall in and got her back in the hangar.

It was a short flight but the SV dished out the fun in spades. I’m liking it.
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RV-12 #202 -- Flying
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  #2  
Old 03-17-2017, 04:44 PM
Aggie78 Aggie78 is offline
 
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Location: Fort Worth, Texas
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Good report.

What I do is when at IAF altitude, I will set MDA/DH using one of the "Knob" selectors; this gives me an alert when approaching minimums.

Once inbound past the FAF, I set missed approach altitude in the Altitude window to "arm" it for a potential missed.

VNAV works pretty slick, especially when coupled up to an LPV or LNAV/VNAV navigator.

I just printed out the Autopilot tuning guide to take flying with me over the weekend to knock down some annoyances with the way it's behaving, but otherwise the sucker does a darn good job!

Rob

ps-edited to add...if you enjoyed flying it in expert mode, you should let your mind wander over getting the Autopilot and Knob panels. HUUUUGE amount easier to use. Practically like flying the Big Jet, now that I have those 2 items....
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Last edited by Aggie78 : 03-17-2017 at 04:51 PM.
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  #3  
Old 03-18-2017, 09:05 AM
olderthandirt olderthandirt is offline
 
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Location: Lopez Island, Wa.
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Default Very interesting stuff

Tony; You make it sound easy...I know nothing of Vnav and have barely used the auto pilot...but still learning and can see how this COULD work if like yourself you know how...nice thing would be if wife could learn this stuff and I croak up there it might make getting down much easier and safer..she has taken right seat training but still this might be a good thing to learn...like you say not for IFR but for fun...
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  #4  
Old 03-18-2017, 12:01 PM
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N941WR N941WR is offline
 
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Now go do some unusual attitudes and engage the AP and watch the fun.
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  #5  
Old 03-18-2017, 12:59 PM
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Tony_T Tony_T is offline
 
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Quote:
Originally Posted by olderthandirt View Post
Tony; You make it sound easy...I know nothing of Vnav and have barely used the auto pilot...but still learning and can see how this COULD work if like yourself you know how...nice thing would be if wife could learn this stuff and I croak up there it might make getting down much easier and safer..she has taken right seat training but still this might be a good thing to learn...like you say not for IFR but for fun...
Dick, I'm definitely still learning as well. What I do is study one of the AP modes in the manual, then make a plan to fly and test out that particular mode. Then move on and combine that with a new mode and task. Right now I am thinking about how the IAS HOLD mode might be useful on a descent. If you set manifold pressure correctly the AP should pitch for a desired airspeed. It would be great if that would work in conjunction with the VNAV descent, but I suspect the IAS button will cancel VNAV. The manual isn't completely clear on this or maybe it is and I am just not seeing it. Another test flight is needed .

I hear your concern about wife safety. Mine will not even attempt to learn flying skills. Best if we take good care of ourselves so we don't croak on them when flying.
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  #6  
Old 03-19-2017, 07:32 AM
Keith Williams Keith Williams is offline
 
Join Date: Mar 2008
Location: Milan, Illinois
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Default UFOs

First,Tony, thanks for the "heads-up" on UFOs. I am two and half years from being eligible and had not been aware of the organization. Looks like a good reason for an RV12 cross country in 2019.

Back to the thread, I agree that learning the advanced autopilot is a great exercise. Even using the "simple" setting I enjoy watching the arc move around as I vary power and speed on descents. I had the Skyview with a GTN640 in the RV6 and had a hard time with the advanced autopilot before adding the separate autopilot control panel. Adding that control panel (and the knob panel) made a huge difference.
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  #7  
Old 03-19-2017, 08:59 AM
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Tony_T Tony_T is offline
 
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Yes, I have the knobs panels and am using them, sort of. I find the small buttons on the little panel are kind of close together and a little bit slippery as compared to the buttons on the SkyView.


During this learning period I have been keeping the AP pitch menu items across the SV screen bottom because it makes it easy to see which parameters are armed, or active. But you can also get that info from the top bar and, with the knobs panels, use the SV menu bar for other things, I know.

I use the knobs panel a lot. It is great for setting the baro, swinging the heading bug, and setting the altitude target bug. Much faster than using the SV joysticks.
Like Aggie78 says above, mimics the Big Jet cockpit. Except I have never flown one of those, or even a small jet.
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RV-12 #202 -- Flying

Last edited by Tony_T : 03-19-2017 at 09:39 AM.
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  #8  
Old 03-19-2017, 01:58 PM
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WingedFrog WingedFrog is offline
 
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This is great stuff and, as a heavy AP user it encourages me to dig into the expert mode. I am wondering how close we can get to automatic landing, including the flare by using only the throttle?
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  #9  
Old 03-20-2017, 08:48 AM
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rv7boy rv7boy is offline
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Default SVT Expert AP Mode

Quote:
Originally Posted by Keith Williams View Post
First,Tony, thanks for the "heads-up" on UFOs. I am two and half years from being eligible and had not been aware of the organization...
I bought my Dad a UFO membership after he turned 80. He was an active pilot until age 85. After my heart surgery in 2009, one of my life goals is to be qualified to be a member of the UFO's. They're always needing new members because...well, you know...

I'm thinking with improved medical procedures, especially in cardiac care, and with the recently announced FAA BasicMed program, there will be a good supply of pilots who qualify for the UFO's.

Thanks Tony for sharing your fun times with your SVT in your RV-12 and for reminding us of the UFO's.
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  #10  
Old 03-20-2017, 05:07 PM
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Tony_T Tony_T is offline
 
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Default More fun, this time dual screen

Another RV-12 on my home aerodrome is dual screen and my posting and emails regarding the expert AP mode generated a flight today with John V. in N412SB. I got to ride right seat with a CFII pilot and my own 10" SVT screen. Two pilot is always more fun than one.

And she's a beauty:


Taxiing to RWY 02 via Alpha:


The flight included a VNAV approach into RWY 20, a low pass to the south and a VNAV approach into the reciprocal RWY 02.

We (John) did quite a bit of button pushing and "what's it doing now?" moments but were able to make it do our bidding, for the most part. Lessons were learned.

Here we are hands on our lap, watching AP fly the ship, and doing a good job of it in that 30 knot crosswind! Had that been in the forecast we probably would not have launched.
As it turned out the AP accurately tracked the GPS course and once past the FAF she took us well below the decision height and with excellent alignment to the runway.


John had his hand hovering on the disconnect button, and took over to make an amazing touchdown. The 12 seems to like a little wind.

Anther great RV-12 day.
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RV-12 #202 -- Flying

Last edited by Tony_T : 03-21-2017 at 12:17 PM.
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