 |
Matronics Email Lists
Web Forum Interface to the Matronics Email Lists
|
| View previous topic :: View next topic |
| Author |
Message |
dreel(at)cox.net
Guest
|
 Posted: Thu Jan 05, 2006 10:15 am Post subject: Airspeed Indicator Error |
 |
|
I just did a balloon test to see if my pitot system would hold pressure. It did, but I got two different airspeed indications & I'm wondering if the UMA unit I bought from Vans can be adjusted. The UMA said I was using a 103 kt balloon but the Dynon D10 said I was using a 109 kt balloon. Have any of you observed differences like these? Which was the most reliable? Anyone know of a book full of numbers and equations that would give me the air pressure that corresponds to 110 kt? It seems to me that a test pilot oriented book of that sort would be pretty useful during the coming months.
Dave Reel - RV8A FAA inspection Jan 25
| | - The Matronics RV-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?RV-List |
|
|
|
| Back to top |
|
 |
dan(at)rvproject.com
Guest
|
| Posted: Thu Jan 05, 2006 10:44 am Post subject: Airspeed Indicator Error |
|
|
Dave,
If it makes you feel any better, my Van's airspeed gauge reads 2-3 mph lower
than my EFIS-D10. I trust the -D10 since when it passed pitot/static,
altitude & airspeed consistently had less (or zero) error on the Dynon than
the "steam gauges."
do not archive
) ( Dan
RV-7 N714D (757 hours)
http://www.rvproject.com
| | - The Matronics RV-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?RV-List |
|
|
|
| Back to top |
|
|
khorton01(at)rogers.com
Guest
|
| Posted: Thu Jan 05, 2006 12:29 pm Post subject: Airspeed Indicator Error |
|
|
On 5 Jan 2006, at 13:15, DAVID REEL wrote:
I just did a balloon test to see if my pitot system would hold
pressure. It did, but I got two different airspeed indications &
I'm wondering if the UMA unit I bought from Vans can be adjusted.
The UMA said I was using a 103 kt balloon but the Dynon D10 said I
was using a 109 kt balloon. Have any of you observed differences
like these? Which was the most reliable? Anyone know of a book
full of numbers and equations that would give me the air pressure
that corresponds to 110 kt? It seems to me that a test pilot
oriented book of that sort would be pretty useful during the coming
months.
|
David,
If all you want is the formula, you can get it at:
http://www.eaa1000.av.org/technicl/instcal/instcal.htm
If you want an Excel spreadsheet I created that converts between ASI
reading and pressure in inches of water, you can get it at:
http://www.kilohotel.com/rv8/filemgmt/visit.php?lid=3
I've got other useful flight test links at:
http://www.kilohotel.com/rv8/phplinks/index.php?PID=1
Just for info, the results of my ASI calibrations (Dynon D-10A and
analog ASI) are at:
http://www.kilohotel.com/rv8/article.php?story=ASI Calibration 2
2 - 3 kt ASI instrument errors are very normal. Five kt errors are
not unusual. Plus there is some friction in the instruments, which
gives some hysteresis. I.e. the ASI number might have increased a kt
or two if there was some vibration, like you would get from your engine.
Kevin Horton RV-8 (finishing kit)
Ottawa, Canada
http://www.kilohotel.com/rv8
| | - The Matronics RV-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?RV-List |
|
|
|
bobperk(at)bellsouth.net
Guest
|
| Posted: Thu Jan 05, 2006 3:01 pm Post subject: Airspeed Indicator Error |
|
|
I found this site to be excellent for my mathematically challenged head.
http://www.iflyez.com/manometer.htm
Bob Perkinson
Hendersonville, TN.
RV9 N658RP Reserved
If nothing changes
Nothing changes
| | - The Matronics RV-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?RV-List |
|
|
|
skytop(at)megsinet.net
Guest
|
| Posted: Mon Jan 09, 2006 1:58 pm Post subject: Airspeed Indicator Error |
|
|
Dave,
You might be able to get something useful by searching the archives on "new
asi calibration". See Kevin Horton's article where he lists the airspeed in
knots and MPH for a number of water column differentials. A differential of
just 31 inches of water represents an airspeed of 250 MPH, so a few yards of
plastic tubing along with a yard stick plus whatever is required to
interface to your pitot tube, is all you need.
I built the test device but at the time, my system leaked down too fast to
get perfect results - as I was working solo.
I think Kevin got his numbers from a MIL specification.
Tom Barnes -6 N442TB
| | - The Matronics RV-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?RV-List |
|
|
|
Get Email Distribution Too!
FAQ
Search
Memberlist
Usergroups
Register
Profile
Log in to check your private messages
Log in
