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Date: Thu, 2 Aug 2007 13:46:14 -0400 (EDT)
Subject: Re: [FlyRotary] Re: EM2 & builder issues
From: jewen@comporium.net
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
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Regarding temperature sensor calibration.  IR pyrometers can have errors
if the user does not fully understand the technology.

Another technique for creating a temperature calibration standard is an
ice bath and/or boiling water bath.  A cup filled with a combination of
water and ice will remain at a constant temperature 32 F until the ice is
gone.  The same is true for boiling water, it will remain 212 F until the
water is gone This is true at sea level and standard pressure (29.92
inHg.)  The melting and boiling points can be calculated for other
pressures.

Joe


On Thu, August 2, 2007 10:52 am, Tracy Crook wrote:
> Dave & John's comments have said it better than I have and as soon as
> Laura
> the web-master gets back from her 50th B-day celebration with her
> girlfriend in NY (at least that where she said she was going : ) I'm going
> to have her add a summary of these points to the website.
>
> Guilty as charged, the average builder is often left out of the equation.
>  The equipment RWS makes reflects my own personal wants, preferences and
> background and the fact that I never intended it to be a commercial
> success.  I still wake up shaking my head that it has done as well as it
> has.
>
> I'm willing to help builders over the rough spots but know what you are
> getting into.  And if you ARE looking for Plug & Play solutions, know that
>  this is not what we offer.
>
> *Fine points on the EM2:*
>
>
> Been wanting to post something on this for some time.  The EM2 offers the
>  ability for the user to calibrate it for a wide range of sensors.  This
> can be a very handy feature in many instances but is a marketing disaster.
> Blue
> Mountain was the only other company to offer this (and one of the reasons
> I
> chose it) and it nearly sank the company.  The average builder ended up
> confused, frustrated and POd.  They eliminated this feature on the new G4
>  series (and added very high priced sensors) : (  and the customer
> problems magically disappeared!   I digress........
>
> The default sensors on the EM2 are very low cost automotive types but
> they are not inherently super accurate.  Usually there in no big down-side
> for the water or oil temp to be off a few degrees so most builders need
> not go any further.  If the water temp turns out to be actually 178
> instead of 180, no big deal.  Super accuracy can be had with these sensors
> if you go to the trouble of calibrating the instrument but then you must
> get into the nitty gritty of the calibration procedures and the troubles
> can begin.
>
> But here is where it does matter.  If you are calculating thermal loads
> and heat dissipation based on differential temps (let's say water temps in
> and out of the radiator for instance)  a few degrees of error can make
> your results meaningless.  In this example, it is not uncommon for the
> Delta T to
> be in the range of 10 degrees at some power settings.  If the error in
> temperature is a couple of degrees, the error is huge, especially if the
> errors are in opposite directions.
>
> Bottom line is, if you need very accurate readings, learn to calibrate
> the EM2 if that is what you are using.  To do this, you need a good
> reference. The easiest way is to use a non-contact (infra-red)
> thermometer.  Harbor Freight and others are now selling inexpensive ones
> for about $10.00.  No reason for any airplane builder not to have one.
> Be sure to paint the test
> points on the part to be measured with a spot of flat black paint to
> eliminate emissivity errors.
>
> Tracy  (should I have said 50th?  )
>
>
> On 8/1/07, John Slade <sladerj@sbcglobal.net> wrote:
>
>>
>> Not unlike the probs John Slade was having because the two oil injector
>>  ports on his rotor housing were not plugged. Wasn't John's fault, but
>> that of his rebuilder. Or the wiring probs John had along the way - I
>> think he smoke tested a few boxes before it was sorted out. He's flying
>> now and having a blast. I say this because there has been at least one
>> contact to Chris offlist where someone was becoming skeptical of the
>> rotary because of our "problems".
>>
>> I agree, Dave. I had more than my fair share of issues and did let the
>> smoke out a couple of times. (Thanks be to Tracy for putting it back
>> with a smile each time). I think it comes down to three things:
>>
>>
>> 1. An amateur (i.e. some who doesn't do this for a living) like Chris
>> or I, is bound to make a few mistakes as we learn. 2. There are a lot of
>> wires and switches in a rotary / EM2/ EC2 installation - i.e. a lot of
>> opportunities to make mistakes. 3. The equipment is not designed for
>> idiots. Sometimes it's not as forgiving as your average household
>> appliance when mistakes are made.
>>
>> This is not "plug and play". The entire installation, beyond the
>> crucial ignition & injection - is complex. Any engine installation with
>> redundant plugs, injectors, ECUs, batteries, possibly dual alternator
>> and, in my case, dual fuel systems, is going to be complex by
>> definition.  There are many opportunities to make errors, and the errors
>> tend to compound and/or hide one another. Much of the complexity is the
>> result of adding the redundancy. It's a challenge to get everything
>> right. It takes time, effort and tenacity, and can be very frustrating,
>> but the end result is a system that is very unlikely to add unintended
>> glider time to your logbook.
>>
>> Chris, if it makes you feel any better, I also had a set of those NC
>> radio shack switches. I think they sell sets with both types in the same
>> pack. I was lucky enough to catch the mistake early on, but I can
>> understand how it could be missed. John
>> Turbo Rotary Cozy IV
>> 94 hours
>>
>>
>>
>>
>>
>>
>> --
>>
>>
>> Homepage:  http://www.flyrotary.com/
>>
>>
>> Archive and UnSub:
>> http://mail.lancaironline.net:81/lists/flyrotary/List.html
>>
>>
>>
>