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Matt Dralle
Site Admin
Joined: 08 Nov 2005
Posts: 26321
Location: Livermore CA USA
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 Posted: Thu Dec 29, 2011 7:36 pm Post subject: Dynon Skyview Airspeed Calibration... |
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At 07:39 PM 12/26/2011 Monday, you wrote:
| Quote: | --> RV-List message posted by: Matt Dralle <dralle(at)matronics.com>
Dear Listers,
I've been flying the new 10" Dynon Skyview in the RV-6 for a few weeks now and it seems like the airspeed is reading maybe 10mph fast. The GS always reads 10mph or more slower than the True airspeed, no matter which way I fly with respect to the current wind. Looking through the configuration options on the Skyview, I'm not seeing parameters to calibrate the airspeed. If the airspeed were *slow* compared to the GS, I could envision making adjustments to the Pitot tube to get it in better alignment with slipstream. But *fast* is a head scratcher. If there's no electronic configuration parameters to adjust, what do you do? Are there Pitot line "attenuators" like for RF in coax? 
Matt |
Listers,
I went flying tonight in the RV-6 around sunset and took some airspeed numbers flying the four points of the compass. I let each direction normalize for about 2 minutes before taking the readings. I've still got my little black-tape washer deals on the static ports that I detailed in a previous email.
Do these numbers make any sense?
I set the altimeter to 30.15 (KLVK ATIS). I compared the Dynon altitude with the Garmin 696 GPS altitude. The Dynon was high by 100 ft. I used the Dynon altitude adjustment to set it to match the GPS (-100ft). The readings above were after this adjustment.
-
Matt "Red Dawg" Dralle
RV-8 #82880 N998RV "Ruby Vixen"
http://www.mattsrv8.com - Matt's Complete RV-8 Construction Log
http://www.mattsrv8.com/Mishap - Landing Mishap Rebuild Log
http://www.youtube.com/MattsRV8 - Matt's RV-8 HDTV YouTube Channel
Status: 172+ Hours TTSN - Rebuilding Fuselage After Landing Mishap...
RV-6 #20916 N360EM "The Flyer"
http://www.mattsrv6.com - Matt's RV-6 Revitalization Log
Status: 48+ Hours Since Purchase - Upgrades Complete; Now In Full Flyer Mode
| | - The Matronics RV10-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
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Matt Dralle
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Kellym
Joined: 10 Jan 2006
Posts: 1705
Location: Sun Lakes AZ
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| Posted: Thu Dec 29, 2011 7:54 pm Post subject: Dynon Skyview Airspeed Calibration... |
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You can use either barometric altitude or pressure altitude. GPS
altitude is irrelevant, It is a calculation based on a theoretical
modified sphere, with some WAAS correction, but ATC and all flight rules
are based on barometric altitude. You can derive pressure altitude from
baro and vice versa, but you can't replicate GPS altitude. With a
portable WAAS enabled receiver I see variations of +/- 150 ft at my
home airport in GPS altitude. Yes, it usually is within 50 ft but not
repeatedly. Are you certain the inputs for the Dynon to calculate TAS
from indicated are correct? Is your indicated temp and baro altitude on
the money?
That set of ground speeds computes to 182 TAS
http://www.reacomp.com/true_airspeed/index.html
So your indicated TAS is still 12 kts high.
On 12/29/2011 8:33 PM, Matt Dralle wrote:
| Quote: | At 07:39 PM 12/26/2011 Monday, you wrote:
>
>
> Dear Listers,
>
> I've been flying the new 10" Dynon Skyview in the RV-6 for a few
> weeks now and it seems like the airspeed is reading maybe 10mph
> fast. The GS always reads 10mph or more slower than the True
> airspeed, no matter which way I fly with respect to the current
> wind. Looking through the configuration options on the Skyview, I'm
> not seeing parameters to calibrate the airspeed. If the airspeed
> were *slow* compared to the GS, I could envision making adjustments
> to the Pitot tube to get it in better alignment with slipstream. But
> *fast* is a head scratcher. If there's no electronic configuration
> parameters to adjust, what do you do? Are there Pitot line
> "attenuators" like for RF in coax?
>
> Matt
Listers,
I went flying tonight in the RV-6 around sunset and took some airspeed
numbers flying the four points of the compass. I let each direction
normalize for about 2 minutes before taking the readings. I've still
got my little black-tape washer deals on the static ports that I
detailed in a previous email.
Do these numbers make any sense?
Emacs!
I set the altimeter to 30.15 (KLVK ATIS). I compared the Dynon
altitude with the Garmin 696 GPS altitude. The Dynon was high by 100
ft. I used the Dynon altitude adjustment to set it to match the GPS
(-100ft). The readings above were after this adjustment.
-
Matt "Red Dawg" Dralle
RV-8 #82880 N998RV "Ruby Vixen"
http://www.mattsrv8.com <http://www.mattsrv8.com/> - Matt's Complete
RV-8 Construction Log
http://www.mattsrv8.com/Mishap - Landing Mishap Rebuild Log
http://www.youtube.com/MattsRV8 - Matt's RV-8 HDTV YouTube Channel
Status: 172+ Hours TTSN - Rebuilding Fuselage After Landing Mishap...
RV-6 #20916 N360EM "The Flyer"
http://www.mattsrv6.com <http://www.mattsrv6.com/> - Matt's RV-6
Revitalization Log
Status: 48+ Hours Since Purchase - Upgrades Complete; Now In Full
Flyer Mode
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Kelly McMullen
A&P/IA, EAA Tech Counselor # 5286
KCHD |
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bwestfall
Joined: 22 Oct 2008
Posts: 131
Location: Portland, OR
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| Posted: Thu Dec 29, 2011 11:35 pm Post subject: Dynon Skyview Airspeed Calibration... |
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Matt,
What type/shape of static ports do you have? I’m wondering if this is an issue with flush static ports??? Airspeed indicator results/calibration has proven more effective with a static port that protrudes a bit from the edge of the skin.
Ben Westfall
From: owner-rv10-list-server(at)matronics.com [mailto:owner-rv10-list-server(at)matronics.com] On Behalf Of Matt Dralle
Sent: Thursday, December 29, 2011 7:34 PM
To: rv-list(at)matronics.com; rv8-list(at)matronics.com; rv7-list(at)matronics.com; rv10-list(at)matronics.com
Subject: Re: Dynon Skyview Airspeed Calibration...
At 07:39 PM 12/26/2011 Monday, you wrote:
--> RV-List message posted by: Matt Dralle <dralle(at)matronics.com>
Dear Listers,
I've been flying the new 10" Dynon Skyview in the RV-6 for a few weeks now and it seems like the airspeed is reading maybe 10mph fast. The GS always reads 10mph or more slower than the True airspeed, no matter which way I fly with respect to the current wind. Looking through the configuration options on the Skyview, I'm not seeing parameters to calibrate the airspeed. If the airspeed were *slow* compared to the GS, I could envision making adjustments to the Pitot tube to get it in better alignment with slipstream. But *fast* is a head scratcher. If there's no electronic configuration parameters to adjust, what do you do? Are there Pitot line "attenuators" like for RF in coax?
Matt
Listers,
I went flying tonight in the RV-6 around sunset and took some airspeed numbers flying the four points of the compass. I let each direction normalize for about 2 minutes before taking the readings. I've still got my little black-tape washer deals on the static ports that I detailed in a previous email.
Do these numbers make any sense?
[img]cid:image001.jpg(at)01CCC682.1AB1CD90[/img]
I set the altimeter to 30.15 (KLVK ATIS). I compared the Dynon altitude with the Garmin 696 GPS altitude. The Dynon was high by 100 ft. I used the Dynon altitude adjustment to set it to match the GPS (-100ft). The readings above were after this adjustment.
-
Matt "Red Dawg" Dralle
RV-8 #82880 N998RV "Ruby Vixen"
http://www.mattsrv8.com - Matt's Complete RV-8 Construction Log
http://www.mattsrv8.com/Mishap - Landing Mishap Rebuild Log
http://www.youtube.com/MattsRV8 - Matt's RV-8 HDTV YouTube Channel
Status: 172+ Hours TTSN - Rebuilding Fuselage After Landing Mishap...
RV-6 #20916 N360EM "The Flyer"
http://www.mattsrv6.com - Matt's RV-6 Revitalization Log
Status: 48+ Hours Since Purchase - Upgrades Complete; Now In Full Flyer Mode
| | - The Matronics RV10-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
http://www.matronics.com/Navigator?RV10-List |
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bwestfall
Joined: 22 Oct 2008
Posts: 131
Location: Portland, OR
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| Posted: Thu Dec 29, 2011 11:37 pm Post subject: Dynon Skyview Airspeed Calibration... |
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Oops I did not read the entire email… I see you already figured it out. Sorry for the spam
-Ben
From: owner-rv10-list-server(at)matronics.com [mailto:owner-rv10-list-server(at)matronics.com] On Behalf Of Matt Dralle
Sent: Thursday, December 29, 2011 7:34 PM
To: rv-list(at)matronics.com; rv8-list(at)matronics.com; rv7-list(at)matronics.com; rv10-list(at)matronics.com
Subject: Re: Dynon Skyview Airspeed Calibration...
At 07:39 PM 12/26/2011 Monday, you wrote:
--> RV-List message posted by: Matt Dralle <dralle(at)matronics.com>
Dear Listers,
I've been flying the new 10" Dynon Skyview in the RV-6 for a few weeks now and it seems like the airspeed is reading maybe 10mph fast. The GS always reads 10mph or more slower than the True airspeed, no matter which way I fly with respect to the current wind. Looking through the configuration options on the Skyview, I'm not seeing parameters to calibrate the airspeed. If the airspeed were *slow* compared to the GS, I could envision making adjustments to the Pitot tube to get it in better alignment with slipstream. But *fast* is a head scratcher. If there's no electronic configuration parameters to adjust, what do you do? Are there Pitot line "attenuators" like for RF in coax?
Matt
Listers,
I went flying tonight in the RV-6 around sunset and took some airspeed numbers flying the four points of the compass. I let each direction normalize for about 2 minutes before taking the readings. I've still got my little black-tape washer deals on the static ports that I detailed in a previous email.
Do these numbers make any sense?
[img]cid:image001.jpg(at)01CCC682.6999D880[/img]
I set the altimeter to 30.15 (KLVK ATIS). I compared the Dynon altitude with the Garmin 696 GPS altitude. The Dynon was high by 100 ft. I used the Dynon altitude adjustment to set it to match the GPS (-100ft). The readings above were after this adjustment.
-
Matt "Red Dawg" Dralle
RV-8 #82880 N998RV "Ruby Vixen"
http://www.mattsrv8.com - Matt's Complete RV-8 Construction Log
http://www.mattsrv8.com/Mishap - Landing Mishap Rebuild Log
http://www.youtube.com/MattsRV8 - Matt's RV-8 HDTV YouTube Channel
Status: 172+ Hours TTSN - Rebuilding Fuselage After Landing Mishap...
RV-6 #20916 N360EM "The Flyer"
http://www.mattsrv6.com - Matt's RV-6 Revitalization Log
Status: 48+ Hours Since Purchase - Upgrades Complete; Now In Full Flyer Mode
| | - The Matronics RV10-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
http://www.matronics.com/Navigator?RV10-List |
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Bob Turner
Joined: 03 Jan 2009
Posts: 885
Location: Castro Valley, CA
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| Posted: Fri Dec 30, 2011 9:15 am Post subject: Re: Dynon Skyview Airspeed Calibration... |
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Matt,
I'd record the indicated airspeeds as well. Use an E-6B or equivalent to see if the true airspeeds you calculate match the Dynon's. Maybe there's a software error, or an input (temperature, altitude) error there.
Since the speeds look uniformly high, I would just note that a static line leak inside the cabin will usually make the airspeeds read high. Try slightly pressurizing the line with a balloon, see if it leaks.
| | - The Matronics RV10-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
http://www.matronics.com/Navigator?RV10-List |
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_________________
Bob Turner
RV-10 QB |
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