REFLECTOR:Pitot problems

Wayne Lanza reflector@tvbf.org
Sat, 4 Oct 2003 12:00:40 -0400


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  I'd like to point out a couple of possible problems with the 'Shark=20
Fin' pitot tubes.
Most of the ones that I've seen include the static port as part of the=20=

fin, they are
easy to spot - just look for the extra holes. This type of pitot has a=20=

nasty power
consumption requirement, like 15-20 amps @ 12v! The extra amps are to=20
heat
the entire tube so as to also keep the static port de-iced. I regard=20
the use of this
unit as basically nuts - they are expensive, use way too much power and=20=

get
really hot. So hot that they require special mounting to keep thermal=20
transfer
from softening the glass. The best thing to do is to replace it with a=20=

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=20=

source, why
not just install two static ports as in the plans?  Oh let me guess,=20
they don't work...
They work fine if installed per plans with a small turbulator or for=20
the purist you can
use the turned aluminum jobs.

  The reason that the pitot manufacturers note that the heater not be=20
turned on
while on the ground is so that you don't get a minor burn if it's=20
touched. If you
need the sanity check put a light on the panel to remind you, it=20
doesn't need
to be tied into the gear system or an airspeed sensor. (They only do=20
that stuff
on the space shuttle)

  Not trying to be too critical here but it seems a lot of effort has of=20=

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:

> =46rom some Reflector postings and off-line comments, it seemed highly=20=

> unlikely that there wouldn't be any markings on the "impossibly put=20
> together pitot".=A0 Apparently, in the plating process, enough metal =
was=20
> displaced that the only way to see the manufacturer's imprint was to=20=

> position=A0a light just-so and hold your mouth just right.=A0 On the=20=

> plane, it looked perfectly smooth on both sides where the imprint was.=20=

> =A0It took a few attempts but I was able to glean the following=20
> information:
>
> Kollsman Mfr No. 369D-011
> AN5816-1, 12-16v
> Patent Canada, 1940
> Patent No. 2.204.367
> =A0
> In checking the web, this AN5816-1 number corresponds to pitots used=20=

> in some old warbirds, though it wasn't possible to tell which ones.=A0=20=

> More currently, that number was used in Aerostars and Piper Aztecs.=A0=20=

> It's called a "sharkfin pitot" due to the, well, sharkfin looking sail=20=

> on the top of the pitot.=A0=A0=A0 Equally surprising, it truly is=A0a =
12v=20
> pitot, not 24v as I was told.=A0 The heavy current draw was from an=20
> internal short that became apparent as I did more testing; apparently=20=

> incurred during the plating process.=A0 Nonetheless, Dave Black's,=A0et=20=

> al, discourse on epower and ecurrent was interesting and informative.=A0=
=20
> I'll post a couple photos when I get the USB working again.=A0 =
However,=20
> anyone that has any idea in how to break into this thing would be most=20=

> welcome to pass along suggestions.=A0 I really want to repair/salvage =
it=20
> if I can.
> =A0
> On a different note,=A0Jim now has me skeptical and fearful=A0about =
flying=20
> near a cloud in a plastic plane.=A0 I'm ever so thankful for the=20
> many=A0times I must have already cheated death's grip.=A0 My personal=20=

> minimums have now gone up to 20,000 overcast with 10 mile visibility=20=

> and low humidity!!
> =A0
> Chuck Jensen, in East Tennessee where gaming Jim is the sport of the=20=

> day.

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 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...=20

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:


<excerpt><fontfamily><param>Arial</param><smaller>=46rom some Reflector
postings and off-line comments, it seemed highly unlikely that there
wouldn't be any markings on the "impossibly put together pitot".=A0
Apparently, in the plating process, enough metal was displaced that
the only way to see the manufacturer's imprint was to position=A0a light
just-so and hold your mouth just right.=A0 On the plane, it looked
perfectly smooth on both sides where the imprint was. =A0It took a few
attempts but I was able to glean the following =
information:</smaller></fontfamily>


<fontfamily><param>Arial</param><smaller>Kollsman Mfr No. =
369D-011</smaller></fontfamily>

<fontfamily><param>Arial</param><smaller>AN5816-1, =
12-16v</smaller></fontfamily>

<fontfamily><param>Arial</param><smaller>Patent Canada, =
1940</smaller></fontfamily>

<fontfamily><param>Arial</param><smaller>Patent No. =
2.204.367</smaller></fontfamily>

=A0

<fontfamily><param>Arial</param><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.=A0 More currently, that
number was used in Aerostars and Piper Aztecs.=A0 It's called a
"sharkfin pitot" due to the, well, sharkfin looking sail on the top of
the pitot.=A0=A0=A0 Equally surprising, it truly is=A0a 12v pitot, not =
24v as
I was told.=A0 The heavy current draw was from an internal short that
became apparent as I did more testing; apparently incurred during the
plating process.=A0 Nonetheless, Dave Black's,=A0et al, discourse on
epower and ecurrent was interesting and informative.=A0 I'll post a
couple photos when I get the USB working again.=A0 However, anyone that
has any idea in how to break into this thing would be most welcome to
pass along suggestions.=A0 I really want to repair/salvage it if I =
can.</smaller></fontfamily>

=A0

<fontfamily><param>Arial</param><smaller>On a different note,=A0Jim now
has me skeptical and fearful=A0about flying near a cloud in a plastic
plane.=A0 I'm ever so thankful for the many=A0times I must have already
cheated death's grip.=A0 My personal minimums have now gone up to 20,000
overcast with 10 mile visibility and low =
humidity!!</smaller></fontfamily>

=A0

<fontfamily><param>Arial</param><smaller>Chuck Jensen, in East
Tennessee where gaming Jim is the sport of the day.

</smaller></fontfamily></excerpt>=

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