Today's Message Index:
----------------------
1. 06:11 AM - Re: Pitot Tube angle (Colin J. Kennedy)
2. 07:23 AM - Re: Pitot Tube angle (N1BZRich@aol.com)
3. 09:19 AM - Re: Pitot Tube angle (Colin J. Kennedy)
4. 10:11 AM - Re: Pitot Tube angle (Jim Langley)
5. 10:12 AM - Re: Pitot Tube angle (Jim Langley)
Message 1
| INDEX | Back to Main INDEX |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | Pitot Tube angle |
Jim,
I would be interested in the answer to your question.
I would also be interested in how you determine the airplane is straight
and
level in the pitch axis?
Colin K.
OK
Lightning # 52 under construction.
http://www.mykitlog.com/cojaken
-----Original Message-----
From: owner-lightning-list-server@matronics.com
[mailto:owner-lightning-list-server@matronics.com] On Behalf Of Jim
Langley
Sent: Friday, December 05, 2008 9:39 PM
Subject: Lightning-List: Pitot Tube angle
All:
I look at my airplane and notice that the pitot tube angles up a little
even
when the aircraft is sitting straight and level; is this correct? If
not,
what all did you do to correct the issue, shim it?
Jim!
Message 2
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | Re: Pitot Tube angle |
In a message dated 12/5/2008 10:39:46 P.M. Eastern Standard Time,
pequeajim@gmail.com writes:
I look at my airplane and notice that the pitot tube angles up a little even
when the aircraft is sitting straight and level; is this correct? If not,
what all did you do to correct the issue, shim it?
HI Jim,
The real key is to have the pitot tube aligned so that it is
perpendicular to the vertical axis and parallel to the longitudinal axis of the
aircraft
when the aircraft is in flight - not when sitting on the ground. Or in
other words for practicable use, aligned with the relative airflow in front of
the wing. Since airplanes fly at different angles of attack at different
airspeeds, the actual alignment with the airflow as it meets the wing obviously
varies as you change speeds. So in reality, the pitot tube alignment is
important, with longitudinal alignment being possibly more critical since we know
that the other alignment will change with angle of attack. So get it as
accurate as you can. But remember that it will only be exact at one angle of
attack.
What is probably more important is the placement of the static ports.
The pitot / static tube measures total pressure (or impact pressure) at the
nose of the pitot tube and the static pressure of the air stream at side
ports. The difference of these pressures, or the dynamic or velocity pressure
varies with the square of the gas velocity. So static source is just as
important, if not more so, than pitot pressure measurement.
The Lightning kit uses a good pitot / static tube with the static ports
right on the tube, so generally your airspeed measurements will be pretty
accurate as long as you have the tube parallel to the longitudinal axis and
perpendicular to the vertical axis when the airplane is at normal cruise speed.
It should be that way when you install it as the plans and build manual call
for. The only problem comes when some "delta alpha" (dumb ass) walks into it
at an airshow and bends it. Yes, that has happened to me at Oshkosh. I
just bent it back to a TLAR measurement and it seems to be OK. (TLAR = that
looks about right).
Hope all this helps.
Buz
**************Make your life easier with all your friends, email, and
favorite sites in one place. Try it now.
Message 3
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | Pitot Tube angle |
Thanks Buz. I think that addresses my question too!
Colin K.
OK
Lightning # 52 under construction.
http://www.mykitlog.com/cojaken
-----Original Message-----
From: owner-lightning-list-server@matronics.com
[mailto:owner-lightning-list-server@matronics.com] On Behalf Of
N1BZRich@aol.com
Sent: Saturday, December 06, 2008 9:23 AM
Subject: Re: Lightning-List: Pitot Tube angle
In a message dated 12/5/2008 10:39:46 P.M. Eastern Standard Time,
pequeajim@gmail.com writes:
I look at my airplane and notice that the pitot tube angles up a little
even
when the aircraft is sitting straight and level; is this correct? If
not,
what all did you do to correct the issue, shim it?
HI Jim,
The real key is to have the pitot tube aligned so that it is
perpendicular to the vertical axis and parallel to the longitudinal axis
of
the aircraft when the aircraft is in flight - not when sitting on the
ground. Or in other words for practicable use, aligned with the
relative
airflow in front of the wing. Since airplanes fly at different angles
of
attack at different airspeeds, the actual alignment with the airflow as
it
meets the wing obviously varies as you change speeds. So in reality,
the
pitot tube alignment is important, with longitudinal alignment being
possibly more critical since we know that the other alignment will
change
with angle of attack. So get it as accurate as you can. But remember
that
it will only be exact at one angle of attack.
What is probably more important is the placement of the static
ports.
The pitot / static tube measures total pressure (or impact pressure) at
the
nose of the pitot tube and the static pressure of the air stream at side
ports. The difference of these pressures, or the dynamic or velocity
pressure varies with the square of the gas velocity. So static source
is
just as important, if not more so, than pitot pressure measurement.
The Lightning kit uses a good pitot / static tube with the static
ports
right on the tube, so generally your airspeed measurements will be
pretty
accurate as long as you have the tube parallel to the longitudinal axis
and
perpendicular to the vertical axis when the airplane is at normal cruise
speed. It should be that way when you install it as the plans and build
manual call for. The only problem comes when some "delta alpha" (dumb
ass)
walks into it at an airshow and bends it. Yes, that has happened to me
at
Oshkosh. I just bent it back to a TLAR measurement and it seems to be
OK.
(TLAR = that looks about right).
Hope all this helps.
Buz
_____
Make your life easier with all your friends, email, and favorite sites
in
one place. Try
lcom00000
010> it now.
Message 4
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | Pitot Tube angle |
I used a digital level with a 2" x 4" and judged it the best I could.
From: owner-lightning-list-server@matronics.com
[mailto:owner-lightning-list-server@matronics.com] On Behalf Of Colin J.
Kennedy
Sent: Saturday, December 06, 2008 9:11 AM
Subject: RE: Lightning-List: Pitot Tube angle
Jim,
I would be interested in the answer to your question.
I would also be interested in how you determine the airplane is straight and
level in the pitch axis?
Colin K.
OK
Lightning # 52 under construction.
http://www.mykitlog.com/cojaken
-----Original Message-----
From: owner-lightning-list-server@matronics.com
[mailto:owner-lightning-list-server@matronics.com] On Behalf Of Jim Langley
Sent: Friday, December 05, 2008 9:39 PM
Subject: Lightning-List: Pitot Tube angle
All:
I look at my airplane and notice that the pitot tube angles up a little even
when the aircraft is sitting straight and level; is this correct? If not,
what all did you do to correct the issue, shim it?
Jim!
href="http://www.matronics.com/contribution">http://www.matronics.com/chref
"http://www.matronics.com/Navigator?Lightning-List">http://www.matronics.com
/Navigator?Lightning-List
href="http://forums.matronics.com">http://forums.matronics.com
Message 5
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | Pitot Tube angle |
(grin), as usual, thanks Buz.
From: owner-lightning-list-server@matronics.com
[mailto:owner-lightning-list-server@matronics.com] On Behalf Of
N1BZRich@aol.com
Sent: Saturday, December 06, 2008 10:23 AM
Subject: Re: Lightning-List: Pitot Tube angle
In a message dated 12/5/2008 10:39:46 P.M. Eastern Standard Time,
pequeajim@gmail.com writes:
I look at my airplane and notice that the pitot tube angles up a little even
when the aircraft is sitting straight and level; is this correct? If not,
what all did you do to correct the issue, shim it?
HI Jim,
The real key is to have the pitot tube aligned so that it is
perpendicular to the vertical axis and parallel to the longitudinal axis of
the aircraft when the aircraft is in flight - not when sitting on the
ground. Or in other words for practicable use, aligned with the relative
airflow in front of the wing. Since airplanes fly at different angles of
attack at different airspeeds, the actual alignment with the airflow as it
meets the wing obviously varies as you change speeds. So in reality, the
pitot tube alignment is important, with longitudinal alignment being
possibly more critical since we know that the other alignment will change
with angle of attack. So get it as accurate as you can. But remember that
it will only be exact at one angle of attack.
What is probably more important is the placement of the static ports.
The pitot / static tube measures total pressure (or impact pressure) at the
nose of the pitot tube and the static pressure of the air stream at side
ports. The difference of these pressures, or the dynamic or velocity
pressure varies with the square of the gas velocity. So static source is
just as important, if not more so, than pitot pressure measurement.
The Lightning kit uses a good pitot / static tube with the static ports
right on the tube, so generally your airspeed measurements will be pretty
accurate as long as you have the tube parallel to the longitudinal axis and
perpendicular to the vertical axis when the airplane is at normal cruise
speed. It should be that way when you install it as the plans and build
manual call for. The only problem comes when some "delta alpha" (dumb ass)
walks into it at an airshow and bends it. Yes, that has happened to me at
Oshkosh. I just bent it back to a TLAR measurement and it seems to be OK.
(TLAR = that looks about right).
Hope all this helps.
Buz
_____
Make your life easier with all your friends, email, and favorite sites in
one place. Try
010> it now.
Other Matronics Email List Services
These Email List Services are sponsored solely by Matronics and through the generous Contributions of its members.
-- Please support this service by making your Contribution today! --
|