newtech

newtech

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The Pitch/Roll Offset Calibration has you level the air frame to the cruise angle of attack. What are you RV-7 builders using for the degree offset from the longeron for the cruise angle of attack? I really don't want to dig out my airfoil reference manuals.

After two and a half years of just flying with an electric turn coordinator and a few steam gauges, this G3X is going to be a lot of fun. Just need to get it calibrated now.
 
Not having any other data to use, I treated the longerons as level and seems to be working fine. Probably best to measure again while in flight, just haven't done it yet.
 
MCA said:
Not having any other data to use, I treated the longerons as level and seems to be working fine. Probably best to measure again while in flight, just haven't done it yet.
Click to expand...

Calibrating with longerons level puts you in the ball park but not perfect. Today was the first flight after calibrating and with the autopilot in altitude hold mode the default attitude symbol is clearly about the width of the indicator too high. I am flying to breakfast tomorrow with a V tail bonanza, twin Comanche and several others so I am pretty sure I will get a good idea what the display looks like flat out:D I want to see what I have throughout the speed range before I re-calibrate. Optimum cruise longeron angle looks like it is going to be some what negative.

Will get some pictures of the display tomorrow
 
man, this is so cool

For the first two and a half years my RV-7A only had an electric turn coordinator, ASI, Altimeter and rate of climb. Playing with my new G3X is just so cool:D

The calibration instructions have you jig the aircraft to the cruising attitude and then perform the AHARS calibration. All well and good but what is the angle for the top longeron at cruise attitude? Zero degrees doesn't work and it looks like something around -1 1/2 or so might be close. The following two pictures were taken this morning on a trip to breakfast at Rough River State Park (2I3). The plane was trimmed out in cruise and the Tru Track Digiflight II auto pilot was flying the plane.

G3X-1.jpg


G3X-2.jpg


Sure would be nice if there was a way I could get the plane trimmed out and just press a button to tell the AHARS to calibrate its pitch angle to what the plane is currently flying. From what I can see the only solution available is re jig the plane up to something negative, re-calibrate and go back out and try it. Darn, have to spend the afternoon flying around again.:D
 
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Found one for my Android phone. Oh darn, have to go flying tomorrow. The phone app looks like a winner. I have the digital level we used during construction but it isn't that convenient to use in the cabin.
 
Little thread deviation here :) Steve according to your APRS tracker you just came from Brazil? Do they have aprs police there?
 
Vlad said:
Little thread deviation here :) Steve according to your APRS tracker you just came from Brazil? Do they have aprs police there?
Click to expand...

You're right. You will also notice I was just in China. I was going to chat with Sam off line about what might be happening here.
 
newtech said:
For the first two and a half years my RV-7A only had an electric turn coordinator, ASI, Altimeter and rate of climb. Playing with my new G3X is just so cool:D

The calibration instructions have you jig the aircraft to the cruising attitude and then perform the AHARS calibration. All well and good but what is the angle for the top longeron at cruise attitude? Zero degrees doesn't work and it looks like something around -1 1/2 or so might be close. The following two pictures were taken this morning on a trip to breakfast at Rough River State Park (2I3). The plane was trimmed out in cruise and the Tru Track Digiflight II auto pilot was flying the plane.

Sure would be nice if there was a way I could get the plane trimmed out and just press a button to tell the AHARS to calibrate its pitch angle to what the plane is currently flying. From what I can see the only solution available is re jig the plane up to something negative, re-calibrate and go back out and try it. Darn, have to spend the afternoon flying around again.:D
Click to expand...

Just got back from a data collection flight. I measured the cruising angle of attack as measured on the top longeron.

TAS Angle of the top Longeron
------ -------------------------------------
168 kts -0.5

138 kts -0.7

95 kts -4.5

I don't have a good feel for the pitch algorithm; if it compensates for a decreasing angle of attack as the cruise speed increases. I guess I should calibrate for the slower region of the speed range since it is going to be more critical.

I think I am going to go back up and get more data points from 138 kts to my 45 kts stall. I don't know how systems like the G5000 handle this but it is going to be fun getting a good handle on just how the G3X display of pitch behaves.

My background is that of a statistical process control software engineer so I love this kind of work.
 
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Remember your cruise aoa will change slightly with aircraft weigh and balance also. The RV 7 may be less sensitive but the Rocket aoa would vary significantly just from fuel burn.

I would set the efis for cruise speed, half fuel, some baggage and either 1 person or 2 depending on how you fly most often.
 
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