Today's Message Index:
----------------------
1. 04:20 AM - Re: Low Air Pressure Sensor (Richard Girard)
2. 05:28 AM - Re: Low Air Pressure Sensor (Charlie England)
3. 05:42 AM - Re: Low Air Pressure Sensor (user9253)
4. 06:10 AM - Re: Low Air Pressure Sensor (Kent or Jackie Ashton)
5. 06:46 AM - Re: Low Air Pressure Sensor (Jared Yates)
6. 07:03 AM - Re: Low Air Pressure Sensor (Kelly McMullen)
7. 07:16 AM - Re: Low Air Pressure Sensor (Jared Yates)
8. 07:23 AM - Re: Low Air Pressure Sensor (Charlie England)
9. 07:27 AM - Re: Low Air Pressure Sensor (Kelly McMullen)
10. 07:45 AM - Re: Low Air Pressure Sensor (Charlie England)
11. 08:08 AM - Re: Low Air Pressure Sensor (Jared Yates)
12. 08:29 AM - Re: Low Air Pressure Sensor (Kelly McMullen)
13. 08:52 AM - Re: Low Air Pressure Sensor (Jared Yates)
14. 10:44 AM - =?utf-8?Q?Low_resistance_measurement? ()
15. 11:16 AM - Re: Low Air Pressure Sensor (Robert L. Nuckolls, III)
16. 11:31 AM - Re: Low resistance measurement (Robert L. Nuckolls, III)
17. 11:31 AM - Re: Pitot Heat Ground (Robert L. Nuckolls, III)
18. 11:32 AM - Re: Alternator B-lead circuit protection (Robert L. Nuckolls, III)
19. 11:58 AM - =?utf-8?Q?Re:__Low_resistance_measurement? ()
20. 12:22 PM - Re: Low Air Pressure Sensor (D L Josephson)
21. 12:22 PM - Re: Low Air Pressure Sensor (D L Josephson)
22. 12:26 PM - Re: Low Air Pressure Sensor (Robert L. Nuckolls, III)
23. 12:27 PM - Re: Low resistance measurement (Robert L. Nuckolls, III)
24. 12:54 PM - Re: Low Air Pressure Sensor (Kelly McMullen)
25. 01:55 PM - Re: Low Air Pressure Sensor (Charlie England)
26. 03:21 PM - Re: Pitot Heat Ground (Kelly McMullen)
Message 1
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| Subject: | Re: Low Air Pressure Sensor |
Make a multi-channel manometer out of irrigation tubing. Cheap and easy. I
think the Rotary engine site still has info on this.
Rick Girard
On Tue, Sep 15, 2015 at 11:03 PM, Jared Yates <email@jaredyates.com> wrote:
> I've found a desire to measure differential air pressure inside the engin
e
> cowl for cooling diagnostics. Some folks have used an old airspeed
> indicator for this role. Is there a better way for someone like me who
> doesn't have an old airspeed indicator? Perhaps some sensors that I coul
d
> plug into a computer to record the measurements? Thanks in advance!
>
> *
>
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Message 2
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| Subject: | Re: Low Air Pressure Sensor |
http://www.digikey.com/product-detail/en/MPX5010DP/MPX5010DP-ND/464054?WT.mc_id=IQ60891383-VQ6-41244574155-VQ16-c&wt.srch=1&wt.medium=cpc&WT.srch=1&WT.medium=cpc
This has been used with a volt meter to do what you're after, but obviously
would require a bit of fabrication. Once built, you could feed multiple
devices to spare 0-5V inputs in an EFIS or engine monitor. The device(s)
and their pressure tubing can remain in the cowl, or where ever they're
needed, with only wires coming back to the cockpit.
The water manometer Richard mentioned is a lot simpler to fabricate, but a
lot a bit harder to use while in flight.
Charlie
On Tue, Sep 15, 2015 at 11:03 PM, Jared Yates <email@jaredyates.com> wrote:
> I've found a desire to measure differential air pressure inside the engine
> cowl for cooling diagnostics. Some folks have used an old airspeed
> indicator for this role. Is there a better way for someone like me who
> doesn't have an old airspeed indicator? Perhaps some sensors that I could
> plug into a computer to record the measurements? Thanks in advance!
>
> *
>
>
> *
>
>
Message 3
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| Subject: | Re: Low Air Pressure Sensor |
When you consider the cost of a pressure transducer and knowledge and skill required
to connect it to a computer, buying an old airspeed indicator is easier
and less expensive.
Alternatives are a differential pressure gauge or a homemade manometer. Omega
sells transducers and gauges.
http://www.omega.com/pptst/PGL-25.html
A manometer can be made with 3/8" clear plastic tubing. Form it into the shape
of a "U" and fill it half full of water. Route the ends of the tubing to the
two areas where pressure needs to be compared.
--------
Joe Gores
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=447106#447106
Message 4
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| Subject: | Re: Low Air Pressure Sensor |
Jared, Maybe you only need to measure the pressure differential above
and blow the cylinders. Lycoming recommends about 5=9D of water
differential, depending on HP. This discussion on the Van=99s
site gave me the idea for a good manometer arrangement. I used it to
run some tests on a Long-ez that were informative.
http://www.vansairforce.com/community/showthread.php?p=978583
-Kent
> On Sep 16, 2015, at 12:03 AM, Jared Yates <email@jaredyates.com>
wrote:
>
> I've found a desire to measure differential air pressure inside the
engine cowl for cooling diagnostics. Some folks have used an old
airspeed indicator for this role. Is there a better way for someone
like me who doesn't have an old airspeed indicator? Perhaps some
sensors that I could plug into a computer to record the measurements?
Thanks in advance!
Message 5
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| Subject: | Re: Low Air Pressure Sensor |
Thanks for the help! In this case I'm wanting to measure the differential
before and after the oil cooler, but I'd also like to check above and below
the cylinders eventually. I hadn't considered the manometer, but I'll look
into that.
On Wed, Sep 16, 2015 at 9:09 AM, Kent or Jackie Ashton <kjashton@vnet.net>
wrote:
> Jared, Maybe you only need to measure the pressure differential above an
d
> blow the cylinders. Lycoming recommends about 5=9D of water differ
ential,
> depending on HP. This discussion on the Van=99s site gave me the i
dea for a
> good manometer arrangement. I used it to run some tests on a Long-ez tha
t
> were informative.
> http://www.vansairforce.com/community/showthread.php?p=978583
>
> -Kent
>
> On Sep 16, 2015, at 12:03 AM, Jared Yates <email@jaredyates.com> wrote:
>
> I've found a desire to measure differential air pressure inside the engin
e
> cowl for cooling diagnostics. Some folks have used an old
> airspeed indicator for this role. Is there a better way for someone like
> me who doesn't have an old airspeed indicator? Perhaps some sensors that
> I could plug into a computer to record the measurements? Thanks in advan
ce!
>
>
Message 6
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| Subject: | Re: Low Air Pressure Sensor |
Many RVs in hot climates have issues with oil cooling. Solutions have
included larger or more efficient coolers, in a few cases adding a
second cooler. If the cooler is fed from the rear baffle by scat tubing.
the differential will be a bit less than the differential above and
below the cylinders, due to losses in the scat tubing and the drop
through the cooler.
On 9/16/2015 6:09 AM, Kent or Jackie Ashton wrote:
> Jared, Maybe you only need to measure the pressure differential above
> and blow the cylinders. Lycoming recommends about 5 of water
> differential, depending on HP. This discussion on the Vans site gave
> me the idea for a good manometer arrangement. I used it to run some
> tests on a Long-ez that were informative.
> http://www.vansairforce.com/community/showthread.php?p=978583
>
> -Kent
>> On Sep 16, 2015, at 12:03 AM, Jared Yates <email@jaredyates.com> wrote:
>>
>> I've found a desire to measure differential air pressure inside the
>> engine cowl for cooling diagnostics. Some folks have used an old
>> airspeed indicator for this role. Is there a better way for someone
>> like me who doesn't have an old airspeed indicator? Perhaps some
>> sensors that I could plug into a computer to record the measurements?
>> Thanks in advance!
Message 7
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| Subject: | Re: Low Air Pressure Sensor |
Thanks Kelly, my theory is that my 4-into-1 exhaust system is radiating a
lot of heat into the lower part of the engine, but before I build a new
exhaust system to test that theory, I'd like to make sure that I'm getting
good flow through the cooler. I don't have the airspeed advantage that the
RVs have, being just a 100-knot airplane.
On Wed, Sep 16, 2015 at 10:01 AM, Kelly McMullen <kellym@aviating.com>
wrote:
> kellym@aviating.com>
>
> Many RVs in hot climates have issues with oil cooling. Solutions have
> included larger or more efficient coolers, in a few cases adding a second
> cooler. If the cooler is fed from the rear baffle by scat tubing. the
> differential will be a bit less than the differential above and below the
> cylinders, due to losses in the scat tubing and the drop through the cool
er.
>
> On 9/16/2015 6:09 AM, Kent or Jackie Ashton wrote:
>
>> Jared, Maybe you only need to measure the pressure differential above
>> and blow the cylinders. Lycoming recommends about 5=9D of water
>> differential, depending on HP. This discussion on the Van=99s sit
e gave me
>> the idea for a good manometer arrangement. I used it to run some tests
on
>> a Long-ez that were informative.
>> http://www.vansairforce.com/community/showthread.php?p=978583
>>
>> -Kent
>>
>>> On Sep 16, 2015, at 12:03 AM, Jared Yates <email@jaredyates.com> wrote:
>>>
>>> I've found a desire to measure differential air pressure inside the
>>> engine cowl for cooling diagnostics. Some folks have used an old airsp
eed
>>> indicator for this role. Is there a better way for someone like me who
>>> doesn't have an old airspeed indicator? Perhaps some sensors that I co
uld
>>> plug into a computer to record the measurements? Thanks in advance!
>>>
>>
>
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===========
>
>
Message 8
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| Subject: | Re: Low Air Pressure Sensor |
More options, if one measurement at a time is sufficient & you want
plug&play:
http://www.ebay.com/sch/i.html?_odkw=pressure+gauge&_osacat=0&_from=R40&_trksid=p2045573.m570.l1311.R10.TR9.TRC6.A0.H0.Xdifferential+pressure.TRS2&_nkw=differential+pressure+meter&_sacat=0
Some are <$40, ready to go.
Charlie
On 9/16/2015 8:45 AM, Jared Yates wrote:
> Thanks for the help! In this case I'm wanting to measure the
> differential before and after the oil cooler, but I'd also like to
> check above and below the cylinders eventually. I hadn't considered
> the manometer, but I'll look into that.
>
> On Wed, Sep 16, 2015 at 9:09 AM, Kent or Jackie Ashton
> <kjashton@vnet.net <mailto:kjashton@vnet.net>> wrote:
>
> Jared, Maybe you only need to measure the pressure differential
> above and blow the cylinders. Lycoming recommends about 5 of
> water differential, depending on HP. This discussion on the Vans
> site gave me the idea for a good manometer arrangement. I used it
> to run some tests on a Long-ez that were informative.
> http://www.vansairforce.com/community/showthread.php?p=978583
>
> -Kent
>> On Sep 16, 2015, at 12:03 AM, Jared Yates <email@jaredyates.com
>> <mailto:email@jaredyates.com>> wrote:
>>
>> I've found a desire to measure differential air pressure inside
>> the engine cowl for cooling diagnostics. Some folks have used an
>> old airspeed indicator for this role. Is there a better way for
>> someone like me who doesn't have an old airspeed indicator?
>> Perhaps some sensors that I could plug into a computer to record
>> the measurements? Thanks in advance!
>
>
Message 9
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| Subject: | Re: Low Air Pressure Sensor |
Could you put heat shields on top of the exhaust pipes.. while stainless
is best, with enough standoff, even aluminum can work. I kind of doubt
your exhaust would be heating the oil from the pipes. Maybe from
blowby. Location of oil cooler and airflow can be tricky. Mooney got it
wrong on their '60s version M20s, putting cooler low on front of
cowling, which is a low pressure area, and in a max performance climb
the airflow actually reverses. Problem was fixed by moving cooler to
rear of engine baffling.
On 9/16/2015 7:15 AM, Jared Yates wrote:
> Thanks Kelly, my theory is that my 4-into-1 exhaust system is
> radiating a lot of heat into the lower part of the engine, but before
> I build a new exhaust system to test that theory, I'd like to make
> sure that I'm getting good flow through the cooler. I don't have the
> airspeed advantage that the RVs have, being just a 100-knot airplane.
>
> On Wed, Sep 16, 2015 at 10:01 AM, Kelly McMullen <kellym@aviating.com
> <mailto:kellym@aviating.com>> wrote:
>
> <kellym@aviating.com <mailto:kellym@aviating.com>>
>
> Many RVs in hot climates have issues with oil cooling. Solutions
> have included larger or more efficient coolers, in a few cases
> adding a second cooler. If the cooler is fed from the rear baffle
> by scat tubing. the differential will be a bit less than the
> differential above and below the cylinders, due to losses in the
> scat tubing and the drop through the cooler.
>
> On 9/16/2015 6:09 AM, Kent or Jackie Ashton wrote:
>
> Jared, Maybe you only need to measure the pressure
> differential above and blow the cylinders. Lycoming
> recommends about 5 of water differential, depending on HP.
> This discussion on the Vans site gave me the idea for a good
> manometer arrangement. I used it to run some tests on a
> Long-ez that were informative.
> http://www.vansairforce.com/community/showthread.php?p=978583
>
> -Kent
>
> On Sep 16, 2015, at 12:03 AM, Jared Yates
> <email@jaredyates.com <mailto:email@jaredyates.com>> wrote:
>
> I've found a desire to measure differential air pressure
> inside the engine cowl for cooling diagnostics. Some
> folks have used an old airspeed indicator for this role.
> Is there a better way for someone like me who doesn't have
> an old airspeed indicator? Perhaps some sensors that I
> could plug into a computer to record the measurements?
> Thanks in advance!
>
>
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Message 10
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| Subject: | Re: Low Air Pressure Sensor |
You don't need to test it; it *is* radiating a lot of heat. :-) But
heat shields that will protect from radiant heat are relatively easy to
make. Also, distance is a big factor (variation on inverse square law).
Only areas where the exhaust is within an inch or two of the engine will
it likely have any significant effect. Years ago, I played with
reflective shielding on the oil pan of my O-320 (RV-4, very tight cowl
and close crossover 4x2 exhaust) and it had no noticeable effect on oil
temps.
I'll bet you're on the right path, looking for air pressure differential
issues. BTW, is the oil cooler mounted so that air can't get trapped in
it? Trapped air can have a huge effect on a heat exchanger's efficiency.
Got pics?
Charlie
On 9/16/2015 9:15 AM, Jared Yates wrote:
> Thanks Kelly, my theory is that my 4-into-1 exhaust system is
> radiating a lot of heat into the lower part of the engine, but before
> I build a new exhaust system to test that theory, I'd like to make
> sure that I'm getting good flow through the cooler. I don't have the
> airspeed advantage that the RVs have, being just a 100-knot airplane.
>
> On Wed, Sep 16, 2015 at 10:01 AM, Kelly McMullen <kellym@aviating.com
> <mailto:kellym@aviating.com>> wrote:
>
> <kellym@aviating.com <mailto:kellym@aviating.com>>
>
> Many RVs in hot climates have issues with oil cooling. Solutions
> have included larger or more efficient coolers, in a few cases
> adding a second cooler. If the cooler is fed from the rear baffle
> by scat tubing. the differential will be a bit less than the
> differential above and below the cylinders, due to losses in the
> scat tubing and the drop through the cooler.
>
> On 9/16/2015 6:09 AM, Kent or Jackie Ashton wrote:
>
> Jared, Maybe you only need to measure the pressure
> differential above and blow the cylinders. Lycoming
> recommends about 5 of water differential, depending on HP.
> This discussion on the Vans site gave me the idea for a good
> manometer arrangement. I used it to run some tests on a
> Long-ez that were informative.
> http://www.vansairforce.com/community/showthread.php?p=978583
>
> -Kent
>
> On Sep 16, 2015, at 12:03 AM, Jared Yates
> <email@jaredyates.com <mailto:email@jaredyates.com>> wrote:
>
> I've found a desire to measure differential air pressure
> inside the engine cowl for cooling diagnostics. Some
> folks have used an old airspeed indicator for this role.
> Is there a better way for someone like me who doesn't have
> an old airspeed indicator? Perhaps some sensors that I
> could plug into a computer to record the measurements?
> Thanks in advance!
>
>
Message 11
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| Subject: | Re: Low Air Pressure Sensor |
Here's one of the oil cooler mounted. It's a 9-row cooler in a triangular
bracket sold for the RV-10, and the outlet is the higher port:
http://bearhawkblue.com/wp-content/uploads/IMG_6711.jpg
Here's one that kind of shows the exhaust situation. It doesn't show well
how the left side cylinders cross under the sump and very close to it:
http://bearhawkblue.com/wp-content/uploads/IMG_6712.jpg
I've been running about 140-150 degrees over ambient temp. After flying,
the oil cooler body measures pretty close to the indicated oil temp with an
infrared thermometer, and I've replaced the vernatherm with no measurable
change. I have good reason to believe that the oil is flowing, which is
why I'd like to verify that the air is flowing too.
On Wed, Sep 16, 2015 at 10:42 AM, Charlie England <ceengland7@gmail.com>
wrote:
> You don't need to test it; it *is* radiating a lot of heat. :-) But heat
> shields that will protect from radiant heat are relatively easy to make.
> Also, distance is a big factor (variation on inverse square law). Only
> areas where the exhaust is within an inch or two of the engine will it
> likely have any significant effect. Years ago, I played with reflective
> shielding on the oil pan of my O-320 (RV-4, very tight cowl and close
> crossover 4x2 exhaust) and it had no noticeable effect on oil temps.
>
> I'll bet you're on the right path, looking for air pressure differential
> issues. BTW, is the oil cooler mounted so that air can't get trapped in i
t?
> Trapped air can have a huge effect on a heat exchanger's efficiency. Got
> pics?
>
> Charlie
>
> On 9/16/2015 9:15 AM, Jared Yates wrote:
>
> Thanks Kelly, my theory is that my 4-into-1 exhaust system is radiating a
> lot of heat into the lower part of the engine, but before I build a new
> exhaust system to test that theory, I'd like to make sure that I'm gettin
g
> good flow through the cooler. I don't have the airspeed advantage that t
he
> RVs have, being just a 100-knot airplane.
>
> On Wed, Sep 16, 2015 at 10:01 AM, Kelly McMullen <kellym@aviating.com>
> wrote:
>
>> <kellym@aviating.com>kellym@aviating.com>
>>
>> Many RVs in hot climates have issues with oil cooling. Solutions have
>> included larger or more efficient coolers, in a few cases adding a secon
d
>> cooler. If the cooler is fed from the rear baffle by scat tubing. the
>> differential will be a bit less than the differential above and below th
e
>> cylinders, due to losses in the scat tubing and the drop through the coo
ler.
>>
>> On 9/16/2015 6:09 AM, Kent or Jackie Ashton wrote:
>>
>>> Jared, Maybe you only need to measure the pressure differential above
>>> and blow the cylinders. Lycoming recommends about 5=9D of water
>>> differential, depending on HP. This discussion on the Van=99s si
te gave me
>>> the idea for a good manometer arrangement. I used it to run some tests
on
>>> a Long-ez that were informative.
>>> http://www.vansairforce.com/community/showthread.php?p=978583
>>>
>>> -Kent
>>>
>>>> On Sep 16, 2015, at 12:03 AM, Jared Yates < <email@jaredyates.com>
>>>> email@jaredyates.com> wrote:
>>>>
>>>> I've found a desire to measure differential air pressure inside the
>>>> engine cowl for cooling diagnostics. Some folks have used an old airs
peed
>>>> indicator for this role. Is there a better way for someone like me wh
o
>>>> doesn't have an old airspeed indicator? Perhaps some sensors that I c
ould
>>>> plug into a computer to record the measurements? Thanks in advance!
>>>>
>>>
>>
> *
>
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www.matronics.com/Navigator?AeroElectric-List>
===========
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om/contribution>
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>
> *
>
>
Message 12
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| Subject: | Re: Low Air Pressure Sensor |
OK. That engine install strongly resembles the RV-10 I have. ;-)
That mount is not the most efficient, due to the need for the air to
make a 90 to enter the cooler and a 90 to exit. Many -10 builders use
an Airflow Performance cooler that is the same size as what Vans
supplies, but has extra row of cooling fins. Some go up to IIRC the 2007
or 2008 size cooler.
The -10 setup runs hot until wheel pants and fairings are installed,
moving cruise from 155 to 165-170 range. I don't know if it is adequate
at 100kt speed for an IO-540.
On 9/16/2015 8:07 AM, Jared Yates wrote:
> Here's one of the oil cooler mounted. It's a 9-row cooler in a
> triangular bracket sold for the RV-10, and the outlet is the higher port:
> http://bearhawkblue.com/wp-content/uploads/IMG_6711.jpg
>
> Here's one that kind of shows the exhaust situation. It doesn't show
> well how the left side cylinders cross under the sump and very close
> to it:
> http://bearhawkblue.com/wp-content/uploads/IMG_6712.jpg
>
> I've been running about 140-150 degrees over ambient temp. After
> flying, the oil cooler body measures pretty close to the indicated oil
> temp with an infrared thermometer, and I've replaced the vernatherm
> with no measurable change. I have good reason to believe that the oil
> is flowing, which is why I'd like to verify that the air is flowing too.
>
>
> On Wed, Sep 16, 2015 at 10:42 AM, Charlie England
> <ceengland7@gmail.com <mailto:ceengland7@gmail.com>> wrote:
>
> You don't need to test it; it *is* radiating a lot of heat. :-)
> But heat shields that will protect from radiant heat are
> relatively easy to make. Also, distance is a big factor (variation
> on inverse square law). Only areas where the exhaust is within an
> inch or two of the engine will it likely have any significant
> effect. Years ago, I played with reflective shielding on the oil
> pan of my O-320 (RV-4, very tight cowl and close crossover 4x2
> exhaust) and it had no noticeable effect on oil temps.
>
> I'll bet you're on the right path, looking for air pressure
> differential issues. BTW, is the oil cooler mounted so that air
> can't get trapped in it? Trapped air can have a huge effect on a
> heat exchanger's efficiency. Got pics?
>
> Charlie
>
> On 9/16/2015 9:15 AM, Jared Yates wrote:
>> Thanks Kelly, my theory is that my 4-into-1 exhaust system is
>> radiating a lot of heat into the lower part of the engine, but
>> before I build a new exhaust system to test that theory, I'd like
>> to make sure that I'm getting good flow through the cooler. I
>> don't have the airspeed advantage that the RVs have, being just a
>> 100-knot airplane.
>>
>> On Wed, Sep 16, 2015 at 10:01 AM, Kelly McMullen
>> <kellym@aviating.com <mailto:kellym@aviating.com>> wrote:
>>
>> <kellym@aviating.com <mailto:kellym@aviating.com>>
>>
>> Many RVs in hot climates have issues with oil cooling.
>> Solutions have included larger or more efficient coolers, in
>> a few cases adding a second cooler. If the cooler is fed from
>> the rear baffle by scat tubing. the differential will be a
>> bit less than the differential above and below the cylinders,
>> due to losses in the scat tubing and the drop through the cooler.
>>
>> On 9/16/2015 6:09 AM, Kent or Jackie Ashton wrote:
>>
>> Jared, Maybe you only need to measure the pressure
>> differential above and blow the cylinders. Lycoming
>> recommends about 5 of water differential, depending on
>> HP. This discussion on the Vans site gave me the idea
>> for a good manometer arrangement. I used it to run some
>> tests on a Long-ez that were informative.
>> http://www.vansairforce.com/community/showthread.php?p=978583
>>
>> -Kent
>>
>> On Sep 16, 2015, at 12:03 AM, Jared Yates
>> <email@jaredyates.com <mailto:email@jaredyates.com>>
>> wrote:
>>
>> I've found a desire to measure differential air
>> pressure inside the engine cowl for cooling
>> diagnostics. Some folks have used an old airspeed
>> indicator for this role. Is there a better way for
>> someone like me who doesn't have an old airspeed
>> indicator? Perhaps some sensors that I could plug
>> into a computer to record the measurements? Thanks
>> in advance!
>>
>>
>
> *ist"
> target="_blank">http://www.matronics.com/Navigator?AeroElectric-Listtp://forums.matronics.com
> _blank">http://www.matronics.com/contribution *
>
>
> http://www.matronics.com/contribution
Message 13
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| Subject: | Re: Low Air Pressure Sensor |
Thanks Kelly, an inadequate oil cooler size is a likely factor. Mine is
only a 360 and not a 540, which is partly why I didn't start with the
13-row cooler in the first place.
Message 14
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| Subject: | =?utf-8?Q?Low_resistance_measurement? |
Qm9iLA0KDQoNCkkgYW0gaW50ZXJlc3RlZCBpbiBjb25zdHJ1Y3RpbmcgYSBsb3cgcmVzaXN0YW5j
ZSBtZWFzdXJlbWVudCBhZGFwdG9yLiAgSSBoYXZlIGEgTE0zMzcuICBDYW4gSSB1c2UgdGhpcyBk
ZXZpY2UsIGluIHBsYWNlIG9mIHRoZSBMTTMxNywgd2l0aCBhIHNtYWxsIG1vZGlmaWNhdGlvbiB0
byB5b3VyIHNjaGVtYXRpYz8NCg0KDQpSb2dlcg=
Message 15
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| Subject: | Re: Low Air Pressure Sensor |
At 11:03 PM 9/15/2015, you wrote:
>I've found a desire to measure differential air
>pressure inside the engine cowl for cooling
>diagnostics.=C2 Some folks have used an old
>airspeed indicator for this role.=C2 Is there a
>better way for someone like me who doesn't have
>an old airspeed indicator?=C2 Perhaps some
>sensors that I could plug into a computer to
>record the measurements?=C2 Thanks in advance!
The quick-n-dirty way is to acquire a low-differential-
pressure like this
http://tinyurl.com/pujah48
There's a number of ranges for these instruments on
eBay. I've got a couple buried in stuff not yet
unpacked from my move to M.L from Wichita. They
ARE g-loading sensitive to a degree so stright-n-
level measurements will be the most meaningful.
An all electronic solution may present in the
form of sensors like this"
http://tinyurl.com/ps2adq9
Amplified analog outputs that can be readily
observed on a multi-meter. No g-loading sensitivities.
Also, you could use a gage sensor as opposed to a
ported differential device as long as the sensor
itself can be positioned at the lower pressure
environs.
Bob . . .
Message 16
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| Subject: | Re: Low resistance measurement |
At 12:38 PM 9/16/2015, you wrote:
>Bob,
>
>I am interested in constructing a low resistance measurement
>adaptor. I have a LM337. Can I use this device, in place of the
>LM317, with a small modification to your schematic?
>
>Roger
>
>
Sure, any of the 3-terminal, adjustable regulators
can be adapted to this service. Here's the schematic
for the AEC9008-3 adapter
Emacs!
If you choose to include the 1.0 Amp excitation
option, be aware that the regulator chip warms
up rapidly. Make QUICK measurements or include
appropriate heat sink. 0.1A measurements
require no heat-sink.
Bob . . .
Message 17
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| Subject: | Re: Pitot Heat Ground |
At 04:55 PM 9/8/2015, you wrote:
>
>I read the faqs, and know the recommendation to just take the pitot
>ground to the chassis.
>
>But I have a specific situation in mind, and would like some
>thoughts on it. I'm building an RV14 and the pitot heat controller
>will be about 4 feet outboard of an ADAHRS in the wing with a built
>in magnetometer. I figured if I ran the 14V/Gnd pair together as
>far from the magnetometer as possible I stood a chance of not
>interfering with it when the heater is on.
>I've gotten a Dynon heated pitot tube with controller. In this
>controller the aluminum controller box is connected to ground as is
>the ground lead leaving the box. Dynon says to a) not use the box
>for ground, and b) run a ground wire all the way to the battery.
>
>So I'm struggling with the idea that my ground wire will return the
>current to the battery in a sufficient way to stifle interference of
>the ADAHRS magnetometer. I figure a lot of current will take the
>controller box path and a lot will take the wire path, but since I
>don't own two ammeters I won't be knowing for sure.
Do I understand that the power ground for pitot
heat connects to chassis ground of the controller?
In other words, if there were NO external ground wire
attached, the pitot heater would continue to function?
>So if the controller box is going to ground, seems like taking the
>ground wire to a lug near the box might as well be done, because I
>won't get an interference benefit running the ground wire back to
>the battery. Lots of people ground the controller locally without
>trouble despite the reccs by Dynon to run a wire all the way back.
Your reasoning seems sound. The LOWEST resistance
ground path will be through the box mounting and
the longer the ground wire, the lower will be its
share of the load.
>Anyone have an expert opinion?
>
>I'm about at the point of blowing off the long ground return and
>just getting a remote magnetometer if it makes a difference.
You're conducting the grand experiment. I think
your interference effects will be minimal. If
the ground currents were being carried on a linear
hunk of structure adjacent to the magnetometer,
the potential for interference is higher than
for the fields associated with sheet current spread
out over the area of the skin. Could you put the
pitot tube on the other wing?
But your gut feeling is correct . . . separate ground
all the way to battery does not speak well of
Dynon's grasp of the art and sciences involved.
Were I designing such a beast, all power wiring
between tube and box . . . and from box to ship's power
would be on twisted pairs with the box providing
EMC grounding only . . . power would float (this
is the way the BIG guys do it).
The Dynon manual speaks to about 3' of harness
between box and tube? Does then cause you mount
the control box close to the magnetometer?
Bob . . .
Message 18
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| Subject: | Re: Alternator B-lead circuit protection |
At 03:41 AM 8/7/2015, you wrote:
>
>Hi everyone. I have a quick question with regards to protecting
>alternator B-leads.
>
>A lot of people do so with ANL fuses, yet I know some aircraft (like
>my C150) do so with a circuit breaker. Of course, a disadvantage of
>the ANL is that if it blew while on a trip, after fixing whatever
>caused the problem, a person would have to source a new fuse which
>could result in the aircraft being grounded waiting for one to be
>shipped (are ANL fuses that easy to find?
B-lead protection is a legacy design philosophy with
roots dating back to generators . . . it pay homage
to failure mode effects analysis rules that ASSUMES
that even unthinkable/unlikely thing will happen
and mitigates the effects.
99.999% of all circuit breakers and fuses installed
on airplanes go the lifetime of the airplane NEVER
being tasked with saving a wire at risk for fault,
overheating and fire. Yet, we have installed tons
of such devices on airplanes from C-140 to B-747
because it's 'never been a bad thing to do.'
This knowledge combined with a fortuitous introduction
to fuse bocks by a Bussmann salesman at OSH gave
rise to the notion that we could save a LOT of weight,
cost of ownership, installation time and panel space
with no impact on a failure tolerant system.
http://tinyurl.com/o3cjb84
Referring to the FARs we find that regulatory (and
for the most part) good design practices will
protect all but battery and engine cranking
conductors from the ravages of a hard fault
(we're talking perhaps 1000 amps here) . . .
that
Breakers
http://tinyurl.com/oypxaot
Current limiters
http://tinyurl.com/k9tmfmh
Fuses vs. breakers
http://tinyurl.com/o9joztv
http://tinyurl.com/pvmvs62
http://tinyurl.com/pw2bbgg
Bob . . .
Message 19
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| Subject: | Re:_AeroElectric-List:_Low_resistance_measurement? |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Message 20
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| Subject: | Re: Low Air Pressure Sensor |
>
> I've found a desire to measure differential air pressure inside the engine
> cowl for cooling diagnostics. Some folks have used an old airspeed
> indicator for this role. Is there a better way for someone like me who
> doesn't have an old airspeed indicator? Perhaps some sensors that I could
> plug into a computer to record the measurements? Thanks in advance!
The simplest is a Magnehelic gauge, search an auction site with
'magnehelic differential' and skip the ones where the pointer doesn't
sit at zero in the picture.
There are differential pressure sensors that produce an analog voltage
output if you have logging capability, such as with an inexpensive
logger like a Dataq DI-145. It is more of a project, with the
requirement to set up a quiet regulated power source for the sensor.
Message 21
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| Subject: | Re: Low Air Pressure Sensor |
>
> I've found a desire to measure differential air pressure inside the engine
> cowl for cooling diagnostics. Some folks have used an old airspeed
> indicator for this role. Is there a better way for someone like me who
> doesn't have an old airspeed indicator? Perhaps some sensors that I could
> plug into a computer to record the measurements? Thanks in advance!
The simplest is a Magnehelic gauge, search an auction site with
'magnehelic differential' and skip the ones where the pointer doesn't
sit at zero in the picture.
There are differential pressure sensors that produce an analog voltage
output if you have logging capability, such as with an inexpensive
logger like a Dataq DI-145. It is more of a project, with the
requirement to set up a quiet regulated power source for the sensor.
Message 22
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| Subject: | Re: Low Air Pressure Sensor |
> An all electronic solution may present in the
> form of sensors like this"
>
>http://tinyurl.com/ps2adq9
>
> Amplified analog outputs that can be readily
> observed on a multi-meter. No g-loading sensitivities.
> Also, you could use a gage sensor as opposed to a
> ported differential device as long as the sensor
> itself can be positioned at the lower pressure
> environs.
I dug around in the archives to see
the last time I used one of these
critters. ONLY about 13 years ago . . .
http://tinyurl.com/qe4z856
Had to get some data on pitot-heater performance
on a Beechjet. Two of the my DAS channels
recorded pressure altitude and IAS as presented
by a couple of amplified transducers. Got these
nice traces on a 'short hop' to 41000 feet
in the venerable ol' flight test airplane
at RAC . . .
http://tinyurl.com/qe4z856
Bob . . .
Message 23
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| Subject: | Re: Low resistance measurement |
At 01:54 PM 9/16/2015, you wrote:
>The LM337 being a negative regulator, can this circuit be used by
>reversing the battery polarity, or there other issues?
>
>Roger
Ooops . . . missed that. Yes, you can turn the battery
around and it will work fine . . .
Bob . . .
Message 24
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| Subject: | Re: Low Air Pressure Sensor |
Not necessarily. Van's supplies the same cooler for both 360 and 540
engines. Most do find the 13 row 2006A cooler needed for the 540.
Airflow systems also supplies a diverter plate to install inside the
mount to ensure not all the air goes through the bottom half of the cooler.
On 9/16/2015 8:50 AM, Jared Yates wrote:
> Thanks Kelly, an inadequate oil cooler size is a likely factor. Mine
> is only a 360 and not a 540, which is partly why I didn't start with
> the 13-row cooler in the first place.
>
> http://www.matronics.com/contribution
Message 25
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| Subject: | Re: Low Air Pressure Sensor |
That SCAT tubing is a prime suspect. It has very high internal skin
drag. A friend with an alt. engine in an RV had several inches of
manifold pressure loss through about 4' of SCAT (admittedly, smaller
diameter, but still....). Most of the RV guys have the cooler mounted on
a similar wedge shaped 'adapter', but the side you have facing the
firewall is typically the inlet, attached to a hole in the engine baffle
where you have your SCAT tube fitting. Your SCAT inlet would be blocked
off (no opening). Yes, there are lots of cracked baffles until the
baffle gets reinforced. :-) But most do cool adequately.
Probably a minor factor, but the cooler exit in the pic is at 90 degrees
to likely flow exiting the cowl. I know that velocity is relatively low
there, but little things do add up....
Charlie
On 9/16/2015 10:07 AM, Jared Yates wrote:
> Here's one of the oil cooler mounted. It's a 9-row cooler in a
> triangular bracket sold for the RV-10, and the outlet is the higher port:
> http://bearhawkblue.com/wp-content/uploads/IMG_6711.jpg
>
> Here's one that kind of shows the exhaust situation. It doesn't show
> well how the left side cylinders cross under the sump and very close
> to it:
> http://bearhawkblue.com/wp-content/uploads/IMG_6712.jpg
>
> I've been running about 140-150 degrees over ambient temp. After
> flying, the oil cooler body measures pretty close to the indicated oil
> temp with an infrared thermometer, and I've replaced the vernatherm
> with no measurable change. I have good reason to believe that the oil
> is flowing, which is why I'd like to verify that the air is flowing too.
>
>
> On Wed, Sep 16, 2015 at 10:42 AM, Charlie England
> <ceengland7@gmail.com <mailto:ceengland7@gmail.com>> wrote:
>
> You don't need to test it; it *is* radiating a lot of heat. :-)
> But heat shields that will protect from radiant heat are
> relatively easy to make. Also, distance is a big factor (variation
> on inverse square law). Only areas where the exhaust is within an
> inch or two of the engine will it likely have any significant
> effect. Years ago, I played with reflective shielding on the oil
> pan of my O-320 (RV-4, very tight cowl and close crossover 4x2
> exhaust) and it had no noticeable effect on oil temps.
>
> I'll bet you're on the right path, looking for air pressure
> differential issues. BTW, is the oil cooler mounted so that air
> can't get trapped in it? Trapped air can have a huge effect on a
> heat exchanger's efficiency. Got pics?
>
> Charlie
>
> On 9/16/2015 9:15 AM, Jared Yates wrote:
>> Thanks Kelly, my theory is that my 4-into-1 exhaust system is
>> radiating a lot of heat into the lower part of the engine, but
>> before I build a new exhaust system to test that theory, I'd like
>> to make sure that I'm getting good flow through the cooler. I
>> don't have the airspeed advantage that the RVs have, being just a
>> 100-knot airplane.
>>
>> On Wed, Sep 16, 2015 at 10:01 AM, Kelly McMullen
>> <kellym@aviating.com <mailto:kellym@aviating.com>> wrote:
>>
>> <kellym@aviating.com <mailto:kellym@aviating.com>>
>>
>> Many RVs in hot climates have issues with oil cooling.
>> Solutions have included larger or more efficient coolers, in
>> a few cases adding a second cooler. If the cooler is fed from
>> the rear baffle by scat tubing. the differential will be a
>> bit less than the differential above and below the cylinders,
>> due to losses in the scat tubing and the drop through the cooler.
>>
>> On 9/16/2015 6:09 AM, Kent or Jackie Ashton wrote:
>>
>> Jared, Maybe you only need to measure the pressure
>> differential above and blow the cylinders. Lycoming
>> recommends about 5 of water differential, depending on
>> HP. This discussion on the Vans site gave me the idea
>> for a good manometer arrangement. I used it to run some
>> tests on a Long-ez that were informative.
>> http://www.vansairforce.com/community/showthread.php?p=978583
>>
>> -Kent
>>
>> On Sep 16, 2015, at 12:03 AM, Jared Yates
>> <email@jaredyates.com <mailto:email@jaredyates.com>>
>> wrote:
>>
>> I've found a desire to measure differential air
>> pressure inside the engine cowl for cooling
>> diagnostics. Some folks have used an old airspeed
>> indicator for this role. Is there a better way for
>> someone like me who doesn't have an old airspeed
>> indicator? Perhaps some sensors that I could plug
>> into a computer to record the measurements? Thanks
>> in advance!
>>
>>
>
Message 26
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| Subject: | Re: Pitot Heat Ground |
I just went through the Dynon Pitot Install manual as a refresher. I
agree that whoever wrote the caution about not grounding the negative
power lead to the wing, for a metal wing aircraft, makes zero sense,
The peak current in question is 10 amps. Wings on multi-engine aircraft
routinely serve as ground path for engine ground and starter currents. I
would be surprised to see any magnetometer interference if the current
were carried in the wing skin. The only issue would be the changing
current as the controller maintained the set temp with more or less
current.
The compass calibration is now done in flight, so it could be done
without pitot heat, then repeated with pitot heat to see if it degraded
at all.
I will have to look at my own install, but since the distance from wing
mounting to forrest of tabs was about 12 ft. I probably just used a
red/black 14 gauge twisted pair to my central grounding point.
I do not understand mounting the Skyview ADAHRS in the wing if there is
any reasonable place for it in the fuselage. If magnetic interference is
the issue, Dynon sells a remote magnetometer that can be mounted near
the outer end of either wing. Performance of the ADAHRS will be better
in the fuselage than within the wing, even is staying within the
recommended 6 ft of centerline, in a wing.
On 9/9/2015 11:20 AM, Robert L. Nuckolls, III wrote:
> At 04:55 PM 9/8/2015, you wrote:
>> <dudley@jdatkinson.net>
>>
>> I read the faqs, and know the recommendation to just take the pitot
>> ground to the chassis.
>>
>> But I have a specific situation in mind, and would like some thoughts
>> on it. I'm building an RV14 and the pitot heat controller will be
>> about 4 feet outboard of an ADAHRS in the wing with a built in
>> magnetometer. I figured if I ran the 14V/Gnd pair together as far
>> from the magnetometer as possible I stood a chance of not interfering
>> with it when the heater is on.
>
>
>> I've gotten a Dynon heated pitot tube with controller. In this
>> controller the aluminum controller box is connected to ground as is
>> the ground lead leaving the box. Dynon says to a) not use the box for
>> ground, and b) run a ground wire all the way to the battery.
>>
>> So I'm struggling with the idea that my ground wire will return the
>> current to the battery in a sufficient way to stifle interference of
>> the ADAHRS magnetometer. I figure a lot of current will take the
>> controller box path and a lot will take the wire path, but since I
>> don't own two ammeters I won't be knowing for sure.
>
> Do I understand that the power ground for pitot
> heat connects to chassis ground of the controller?
> In other words, if there were NO external ground wire
> attached, the pitot heater would continue to function?
>
>> So if the controller box is going to ground, seems like taking the
>> ground wire to a lug near the box might as well be done, because I
>> won't get an interference benefit running the ground wire back to the
>> battery. Lots of people ground the controller locally without trouble
>> despite the reccs by Dynon to run a wire all the way back.
>
> Your reasoning seems sound. The LOWEST resistance
> ground path will be through the box mounting and
> the longer the ground wire, the lower will be its
> share of the load.
>
>
>> Anyone have an expert opinion?
>>
>> I'm about at the point of blowing off the long ground return and just
>> getting a remote magnetometer if it makes a difference.
>
> You're conducting the grand experiment. I think
> your interference effects will be minimal. If
> the ground currents were being carried on a linear
> hunk of structure adjacent to the magnetometer,
> the potential for interference is higher than
> for the fields associated with sheet current spread
> out over the area of the skin. Could you put the
> pitot tube on the other wing?
>
> But your gut feeling is correct . . . separate ground
> all the way to battery does not speak well of
> Dynon's grasp of the art and sciences involved.
>
> Were I designing such a beast, all power wiring
> between tube and box . . . and from box to ship's power
> would be on twisted pairs with the box providing
> EMC grounding only . . . power would float (this
> is the way the BIG guys do it).
>
> The Dynon manual speaks to about 3' of harness
> between box and tube? Does then cause you mount
> the control box close to the magnetometer?
>
>
> Bob . . .
>
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