AeroElectric-List Digest Archive

Fri 09/21/12


Total Messages Posted: 6



Today's Message Index:
----------------------
 
     1. 01:57 AM - Re: 30V battery for Tripplet 630 meter (Robert L. Nuckolls, III)
     2. 02:39 AM - Re: Why did this AMP crimp on connection get singed and fail? (Robert L. Nuckolls, III)
     3. 10:13 AM - Re: Pitot tube slightly plugged... (Robert L. Nuckolls, III)
     4. 03:01 PM - Suggestion for Adjustable Regulated DC Power supply (plevyakh)
     5. 08:09 PM - Re: Suggestion for Adjustable Regulated DC Power supply (Robert L. Nuckolls, III)
     6. 09:45 PM - Re: Re: Pitot tube slightly plugged... (Mike Wynn)
 
 
 


Message 1


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    Time: 01:57:28 AM PST US
    From: "Robert L. Nuckolls, III" <nuckolls.bob@aeroelectric.com>
    Subject: Re: 30V battery for Tripplet 630 meter
    At 08:35 PM 9/20/2012, you wrote: >Greetings Listers. > >For those that are interested, here is my solution to the 30V >battery question for the Tripplet 630 meter. Great work-around! Thanks for sharing. Bob . . .


    Message 2


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    Time: 02:39:49 AM PST US
    From: "Robert L. Nuckolls, III" <nuckolls.bob@aeroelectric.com>
    Subject: Re: Why did this AMP crimp on connection get singed
    and fail? > >Everything about the crimp appears fine to me. I used a band saw to >cut half way thru it but it looks solid. > >Any thoughts about what would cause the singeing and the variable >voltage? I'd like to understand what went wrong with this crimp. The rubber hits the road for crimped terminals inside the wire grip area. The terminal's wire grip barrel must be closed down over the wire strands such that no voids exist within the stranding. Here's a microscopic photo of how the gas-tight crimp looks when cross-sectioned. http://www.aeroelectric.com/articles/CrimpTools/GR.jpg I wish I had the polishing jig we used at HBC to smooth these cuts. When really smooth, you can see the squashed wires because each strand is 'ringed' by its tin coating. When the crimp height is too tall, moisture laden air can get between the strands and a corrosion cycle starts with subsequent increases in resistance for the joint. The small voltage drop x load current is a few milliwatts to begin with but as the corrosion (aggravated by rising temperatures) advances, the rate of joint degradation accelerates. Time to operational failure can be long . . . as some have noted, hundreds of flight hours over years of calendar time. Strobe supplies are the most likely to manifest this failure due to their 100% duty cycle, significant current draw in most airplanes. Unless the current is high enough to start the corrosion acceleration, poorly crimped terminals may never manifest failure. See: http://tinyurl.com/93yweyd http://tinyurl.com/bqznffp The inline splice of spade terminals in this photo http://rv6aproject.ckhand.com/panelAndElectrical/electrical/electricalPg6.htm#photo3 would best be replaced with PIDG butt splices or lap-solder/shrink joints. Ideally, the ship's harness would have been extended on down to pins in the connector that mates with power supply. Bob . . .


    Message 3


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    Time: 10:13:22 AM PST US
    From: "Robert L. Nuckolls, III" <nuckolls.bob@aeroelectric.com>
    Subject: Re: Pitot tube slightly plugged...
    At 06:21 PM 9/20/2012, you wrote: <snip> Called the factory in OH, and related a new-to-them technique of removing the obstacle. Good feeling to re-invent the wheel, a bit. BTW, the manufacturing process and subsequent internal road map knowledge IS proprietary... short of destroying the $600 p-tube. It would be really interesting to know the makeup of the obstruction. The interior passages for a pitot tube are a maze of holes, turns, drains and baffles designed to strip high velocity moisture (wet or frozen) from the air sample, keep it warm enough remain liquid, and allow a real sample of dynamic pressure to be impressed upon ship's instruments. http://aeroelectric.com/Pictures/Pitot_Tube/Pitot_Tube_Heater.jpg The fact that you were unable to physically dislodge it suggests it was buried around a sharp turn or hiding behind a baffle. I'm thinking that it was probably a spider nest where adult but tiny creatures carried a succession of materials inside and built an obstructing volume. Pitot tube covers are a GOOD thing and it wouldn't hurt if they were TIGHT. Perhaps a piece of slip-fit hose or tubing. I got to work with the folks at Aero Instruments when HBC was wrestling with what appeared to be 'clear air' blocking of one and sometimes both pitot tubes on airplanes cruising a high altitude. The instruments always recovered at lower altitude/warmer atmosphere. It had to be ice accumulating in a poorly deiced volume within the tube. The problem was to figure out exactly where and how. Not all spaces within the dynamic pressure vessel are held above freezing when the OAT is -50C or so. Interesting story . . . and I'm please to hear that you were able to salvage an otherwise useless piece of expensive hardware! Bob . . .


    Message 4


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    Time: 03:01:14 PM PST US
    Subject: Suggestion for Adjustable Regulated DC Power supply
    From: "plevyakh" <hplevyak@mac.com>
    Can anyone suggest a decent Adjustable Regulated DC Power supply I could use to perform the OVM-14 protection module calibration? How about something from MFJ enterprises? Per the attached bench test from Bob, I'd need something adjustable up to 16.25 volts. Thanks for your suggestions and help here. Howard -------- Howard Plevyak GlaStar / North Bend, Ohio hplevyak@mac.com Read this topic online here: http://forums.matronics.com/viewtopic.php?p=383744#383744 Attachments: http://forums.matronics.com//files/ovm_14_module_bench_test_851.gif


    Message 5


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    Time: 08:09:51 PM PST US
    From: "Robert L. Nuckolls, III" <nuckolls.bob@aeroelectric.com>
    Subject: Re: Suggestion for Adjustable Regulated DC Power
    supply At 04:59 PM 9/21/2012, you wrote: > >Can anyone suggest a decent Adjustable Regulated DC Power supply I >could use to perform the OVM-14 protection module calibration? > >How about something from MFJ enterprises? Per the attached bench >test from Bob, I'd need something adjustable up to 16.25 volts. > >Thanks for your suggestions and help here. This item on eBay is a lot of $value$ for and adjustable 150w power supply. I gave twice that for it's great grandfather in a 90W version about 10 years ago. http://tinyurl.com/8pw7xdg Bob . . .


    Message 6


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    Time: 09:45:12 PM PST US
    From: "Mike Wynn" <wynaire@citlink.net>
    Subject: Re: Pitot tube slightly plugged...
    Thanks for the illustrative cutaways and info Bob. These PT's are much more sophisticated than at a 2nd glance. And your pix do indicate the same pathway my safety wire probe was trying to navigate. The "remains" are stored for photo-micro graphing later on in the slightly "green" depleted battery acid. However, the heater elements still perform per Aero Instruments test-for-certification specs on element amp draw and resistance. So, despite a little brightening of the copper and identical air-flow based on a non-plugged same model p-tube, all is well. Life is interesting. Heater element test specs on Aero Instruments' Pitot Tube model PH502 series: 12 vdc pitot element should draw 6.34 to 8 amps after 2 minutes operation. A 24 vdc pitot element [same model] should draw 3.17 to 4 amps after 2 minutes operation. Resistance in ohms should range from 0.1 to 400. This info is also available as a .pdf at their web site: www.aero-inst.com/products/aeroph502.php. Mike ********** ----- Original Message ----- From: "Robert L. Nuckolls, III" <nuckolls.bob@aeroelectric.com> Sent: Friday, September 21, 2012 11:11 AM Subject: AeroElectric-List: Re: Pitot tube slightly plugged... > <nuckolls.bob@aeroelectric.com> > > At 06:21 PM 9/20/2012, you wrote: > > <snip> > > Called the factory in OH, and related a new-to-them technique of removing > the obstacle. Good feeling to re-invent the wheel, a bit. BTW, the > manufacturing process and subsequent internal road map knowledge IS > proprietary... short of destroying the $600 p-tube. > > It would be really interesting to know the > makeup of the obstruction. > > The interior passages for a pitot tube are > a maze of holes, turns, drains and baffles > designed to strip high velocity moisture > (wet or frozen) from the air sample, keep > it warm enough remain liquid, and allow > a real sample of dynamic pressure to be > impressed upon ship's instruments. > > http://aeroelectric.com/Pictures/Pitot_Tube/Pitot_Tube_Heater.jpg > > The fact that you were unable to physically > dislodge it suggests it was buried around > a sharp turn or hiding behind a baffle. I'm > thinking that it was probably a spider nest > where adult but tiny creatures carried a succession > of materials inside and built an obstructing > volume. Pitot tube covers are a GOOD thing > and it wouldn't hurt if they were TIGHT. Perhaps > a piece of slip-fit hose or tubing. > > I got to work with the folks at Aero Instruments > when HBC was wrestling with what appeared to > be 'clear air' blocking of one and sometimes > both pitot tubes on airplanes cruising a > high altitude. The instruments always recovered > at lower altitude/warmer atmosphere. > > It had to be ice accumulating in a poorly > deiced volume within the tube. The problem > was to figure out exactly where and how. > Not all spaces within the dynamic pressure > vessel are held above freezing when the > OAT is -50C or so. > > Interesting story . . . and I'm please to > hear that you were able to salvage an otherwise > useless piece of expensive hardware! > > Bob . . . > > >




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