REFLECTOR:Pitot problems
Chuck Jensen
reflector@tvbf.org
Sat, 4 Oct 2003 13:09:23 -0400
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Wayne,
Well, that may explain the high current draw, though through rudimentary
testing, I had attributed it to a near-dead short. You're correct (as you
often are) in that it does contain a static port. However, the pitot static
port is my back up and the primary static port is per-plans....and they
work!
I understand it's way too expensive, draws too much power and gets really
hot. However, if we threw away all the things that met that criteria, none
of us would own Velocities.
Chuck Jensen
-----Original Message-----
From: reflector-admin@tvbf.org [mailto:reflector-admin@tvbf.org]On Behalf Of
Wayne Lanza
Sent: Saturday, October 04, 2003 11:01 AM
To: reflector@tvbf.org
Subject: REFLECTOR:Pitot problems
I'd like to point out a couple of possible problems with the 'Shark Fin'
pitot tubes.
Most of the ones that I've seen include the static port as part of the fin,
they are
easy to spot - just look for the extra holes. This type of pitot has a nasty
power
consumption requirement, like 15-20 amps @ 12v! The extra amps are to heat
the entire tube so as to also keep the static port de-iced. I regard the use
of this
unit as basically nuts - they are expensive, use way too much power and get
really hot. So hot that they require special mounting to keep thermal
transfer
from softening the glass. The best thing to do is to replace it with a new
one.
With some heaters the coils tend to oxidize with age and go away.
If you are going to fly IFR you are required to have a second static source,
why
not just install two static ports as in the plans? Oh let me guess, they
don't work...
They work fine if installed per plans with a small turbulator or for the
purist you can
use the turned aluminum jobs.
The reason that the pitot manufacturers note that the heater not be turned
on
while on the ground is so that you don't get a minor burn if it's touched.
If you
need the sanity check put a light on the panel to remind you, it doesn't
need
to be tied into the gear system or an airspeed sensor. (They only do that
stuff
on the space shuttle)
Not trying to be too critical here but it seems a lot of effort has of late
gone into
redesigning and fixing a problem that ain't really there...
Fly Safe,
Wayne Lanza
_______________________________________________________________
On Saturday, October 4, 2003, at 11:18 AM, Chuck Jensen wrote:
<?fontfamily><?param Arial><?smaller>From some Reflector postings and
off-line comments, it seemed highly unlikely that there wouldn't be any
markings on the "impossibly put together pitot". Apparently, in the plating
process, enough metal was displaced that the only way to see the
manufacturer's imprint was to position a light just-so and hold your mouth
just right. On the plane, it looked perfectly smooth on both sides where
the imprint was. It took a few attempts but I was able to glean the
following information:<?/smaller><?/fontfamily>
<?fontfamily><?param Arial><?smaller>Kollsman Mfr No.
369D-011<?/smaller><?/fontfamily>
<?fontfamily><?param Arial><?smaller>AN5816-1,
12-16v<?/smaller><?/fontfamily>
<?fontfamily><?param Arial><?smaller>Patent Canada,
1940<?/smaller><?/fontfamily>
<?fontfamily><?param Arial><?smaller>Patent No.
2.204.367<?/smaller><?/fontfamily>
<?fontfamily><?param Arial><?smaller>In checking the web, this AN5816-1
number corresponds to pitots used in some old warbirds, though it wasn't
possible to tell which ones. More currently, that number was used in
Aerostars and Piper Aztecs. It's called a "sharkfin pitot" due to the,
well, sharkfin looking sail on the top of the pitot. Equally surprising,
it truly is a 12v pitot, not 24v as I was told. The heavy current draw was
from an internal short that became apparent as I did more testing;
apparently incurred during the plating process. Nonetheless, Dave Black's,
et al, discourse on epower and ecurrent was interesting and informative.
I'll post a couple photos when I get the USB working again. However, anyone
that has any idea in how to break into this thing would be most welcome to
pass along suggestions. I really want to repair/salvage it if I
can.<?/smaller><?/fontfamily>
<?fontfamily><?param Arial><?smaller>On a different note, Jim now has me
skeptical and fearful about flying near a cloud in a plastic plane. I'm
ever so thankful for the many times I must have already cheated death's
grip. My personal minimums have now gone up to 20,000 overcast with 10 mile
visibility and low humidity!!<?/smaller><?/fontfamily>
<?fontfamily><?param Arial><?smaller>Chuck Jensen, in East Tennessee where
gaming Jim is the sport of the day.
<?/smaller><?/fontfamily>
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<DIV><FONT face=Arial color=#0000ff size=2><SPAN
class=593192316-04102003>Wayne,</SPAN></FONT></DIV>
<DIV><FONT face=Arial color=#0000ff size=2><SPAN
class=593192316-04102003></SPAN></FONT> </DIV>
<DIV><FONT face=Arial color=#0000ff size=2><SPAN class=593192316-04102003>Well,
that may explain the high current draw, though through rudimentary testing, I
had attributed it to a near-dead short. You're correct (as you often are)
in that it does contain a static port. However, the pitot static port is
my back up and the primary static port is per-plans....and they
work!</SPAN></FONT></DIV>
<DIV><FONT face=Arial color=#0000ff size=2></FONT> </DIV>
<DIV><SPAN class=593192316-04102003><FONT face=Arial color=#0000ff size=2>I
understand it's way too expensive, draws too much power and gets really
hot. However, if we threw away all the things that met that criteria, none
of us would own Velocities.</FONT></SPAN></DIV>
<P><FONT face=Arial size=2>Ch</FONT><FONT face=Arial size=2>uck</FONT><FONT
face=Arial size=2> Jensen</FONT> <BR></P>
<BLOCKQUOTE dir=ltr style="MARGIN-RIGHT: 0px">
<DIV class=OutlookMessageHeader dir=ltr align=left><FONT face=Tahoma
size=2>-----Original Message-----<BR><B>From:</B> reflector-admin@tvbf.org
[mailto:reflector-admin@tvbf.org]<B>On Behalf Of </B>Wayne
Lanza<BR><B>Sent:</B> Saturday, October 04, 2003 11:01 AM<BR><B>To:</B>
reflector@tvbf.org<BR><B>Subject:</B> REFLECTOR:Pitot
problems<BR><BR></FONT></DIV>I'd like to point out a couple of possible
problems with the 'Shark Fin' pitot tubes.<BR>Most of the ones that I've seen
include the static port as part of the fin, they are<BR>easy to spot - just
look for the extra holes. This type of pitot has a nasty power<BR>consumption
requirement, like 15-20 amps @ 12v! The extra amps are to heat<BR>the entire
tube so as to also keep the static port de-iced. I regard the use of
this<BR>unit as basically nuts - they are expensive, use way too much power
and get<BR>really hot. So hot that they require special mounting to keep
thermal transfer<BR>from softening the glass. The best thing to do is to
replace it with a new one.<BR>With some heaters the coils tend to oxidize with
age and go away.<BR><BR>If you are going to fly IFR you are required to have a
second static source, why<BR>not just install two static ports as in the
plans? Oh let me guess, they don't work... <BR>They work fine if installed per
plans with a small turbulator or for the purist you can<BR>use the turned
aluminum jobs.<BR><BR>The reason that the pitot manufacturers note that the
heater not be turned on<BR>while on the ground is so that you don't get a
minor burn if it's touched. If you<BR>need the sanity check put a light on the
panel to remind you, it doesn't need<BR>to be tied into the gear system or an
airspeed sensor. (They only do that stuff<BR>on the space shuttle)<BR><BR>Not
trying to be too critical here but it seems a lot of effort has of late gone
into<BR>redesigning and fixing a problem that ain't really there...<BR><BR>Fly
Safe,<BR>Wayne
Lanza<BR>_______________________________________________________________<BR><BR>On
Saturday, October 4, 2003, at 11:18 AM, Chuck Jensen wrote:<BR><BR>
<BLOCKQUOTE><?fontfamily><?param Arial><?smaller>From some Reflector
postings and off-line comments, it seemed highly unlikely that there
wouldn't be any markings on the "impossibly put together pitot".
Apparently, in the plating process, enough metal was displaced that the only
way to see the manufacturer's imprint was to position a light just-so
and hold your mouth just right. On the plane, it looked perfectly
smooth on both sides where the imprint was. It took a few attempts but
I was able to glean the following
information:<?/smaller><?/fontfamily><BR><BR><?fontfamily><?param Arial><?smaller>Kollsman
Mfr No. 369D-011<?/smaller><?/fontfamily><BR><?fontfamily><?param Arial><?smaller>AN5816-1,
12-16v<?/smaller><?/fontfamily><BR><?fontfamily><?param Arial><?smaller>Patent
Canada, 1940<?/smaller><?/fontfamily><BR><?fontfamily><?param Arial><?smaller>Patent
No. 2.204.367<?/smaller><?/fontfamily><BR> <BR><?fontfamily><?param Arial><?smaller>In
checking the web, this AN5816-1 number corresponds to pitots used in some
old warbirds, though it wasn't possible to tell which ones. More
currently, that number was used in Aerostars and Piper Aztecs. It's
called a "sharkfin pitot" due to the, well, sharkfin looking sail on the top
of the pitot. Equally surprising, it truly is a 12v
pitot, not 24v as I was told. The heavy current draw was from an
internal short that became apparent as I did more testing; apparently
incurred during the plating process. Nonetheless, Dave
Black's, et al, discourse on epower and ecurrent was interesting and
informative. I'll post a couple photos when I get the USB working
again. However, anyone that has any idea in how to break into this
thing would be most welcome to pass along suggestions. I really want
to repair/salvage it if I can.<?/smaller><?/fontfamily><BR> <BR><?fontfamily><?param Arial><?smaller>On
a different note, Jim now has me skeptical and fearful about
flying near a cloud in a plastic plane. I'm ever so thankful for the
many times I must have already cheated death's grip. My personal
minimums have now gone up to 20,000 overcast with 10 mile visibility and low
humidity!!<?/smaller><?/fontfamily><BR> <BR><?fontfamily><?param Arial><?smaller>Chuck
Jensen, in East Tennessee where gaming Jim is the sport of the day.<BR><?/smaller><?/fontfamily></BLOCKQUOTE></BLOCKQUOTE></BODY></HTML>
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