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Direction Indicator Needs

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bakerocb

Joined: 15 Jan 2006
Posts: 727
Location: FAIRFAX VA

Posted: Tue Jun 10, 2014 10:25 am Post subject: Direction Indicator Needs

6/10/2014

  

 Hello Aeroelectric and Avionics Listers, I know that there are many  technically smart people on these lists and I would like to enlist your  assistance.

  

 Picture this situation: There are hundreds (maybe thousands) of EAB  (Experimental Amateur Built) IFR capable aircraft flying around with vacuum  driven mechanical spinning mass gyroscopic attitude and directional indicators.  A large percentage of these builders and pilots would like to (or need to)  replace those indicators with something electronic (other than expensive  electrical motor driven mechanical spinning mass gyroscopic) in nature and  remove the entire vacuum system from their EAB.

  

 Replacing the attitude indicator does not appear to be a big problem in  meeting the requirement of 14 CFR 91.205 (d) ( “Gyroscopic pitch and bank  indicator (artificial horizon)” since there are several offerings available.  Here are some:

  

 http://www.dynonavionics.com/docs/D6_intro.html

  

 http://trutrakap.com/product/gemini-pfd/

  

 http://www.grtavionics.com/mini.html

  

 http://www.sandia.aero/?q=node/80

  

 But there does not appear to be available an electronic directional  indicator that would meet the 14 CFR 91.205 (d) (9) criteria for a “Gyroscopic  directional indicator (directional gyro or equivalent)” if one believes that the  Regulatory intended direction to be indicated must indeed be the current  aircraft magnetic heading and not the current aircraft magnetic course (provided  by GPS) over the surface.

  

 I feel that somewhere in the electronic magic that MEMS 

  

 << https://www.memsnet.org/mems/what_is.html  >>

  

 and AHARS 

  

 << http://www.microstrain.com/inertial/3DM-GX3-25?gclid=CjgKEAjw2dqcBRC2q-LXjpfxjnQSJAAeYF5LUC4gvWycBVg6DDW_mzzSdTyyF3q0yoQHrT6ij9VbvvD_BwE  >>

  

 represents there must be a practical, relatively inexpensive means of  creating a direction indicator that will meet the intended requirements of 14  CFR 91.205  (d) (9). If so, I (and probably many others) would like to buy  one for my EAB airplane.

  

 How about it experts (and entrepreneurs) are my desires hopeless and  unrealistic?

  

 OC

  

 'O C' Baker says "The best investment you  can make is the effort to gather and understand information."

  

  

  

   [quote][b]

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bakerocb

Joined: 15 Jan 2006
Posts: 727
Location: FAIRFAX VA

Posted: Tue Jun 10, 2014 2:14 pm Post subject: Direction Indicator Needs

6/10/2014



Hello Dj Merrill, Thanks for your quick response. You wrote: "....  an 

external magnetometer box which gives magnetic heading

information to the EFIS."



1) See here for information on what constitutes a magnetometer:



http://science.howstuffworks.com/magnetometer-info.htm



If the heading that appears on the display, see here:



http://www.grtavionics.com/mini.html#Features



is simply the indication of a remotely located magnetometer (which is 

available for the Mini-X and Mini-AP, but not the Mini-B) then I don't think 

that will meet the intended requirement of 14 CFR 91.205 (d) (9) criteria 

for a “Gyroscopic directional indicator (directional gyro or equivalent)”.



2) One other big downside of the Mini displays from GRT was GRT's failure to 

package the units such that they could be readily installed in a standard 

round nominally 3 inch instrument cut out hole where the old attitude 

indicator resides. See here:



http://www.grtavionics.com/Mini%20Drawing%202.pdf



Needing to cut panel metal to install a Mini unit from GRT in an existing 

panel raises the difficulty of a swap over significantly. Note that Sandia 

recognized the significance of this issue and packaged the SAI 340 - Quattro 

accordingly. See here:



http://www.sandia.aero/?q=system/files/SAI340BroR2Web.pdf



I am still searching.



OC



====================================================================



From: Dj Merrill

Sent: Tuesday, June 10, 2014 3:34 PM

To: aeroelectric-list(at)matronics.com ; bakerocb(at)cox.net

Subject: Re: AeroElectric-List: Direction Indicator Needs



I am not familiar with the other brands, but the GRT EFIS units come

with an external magnetometer box which gives magnetic heading

information to the EFIS.



Is that what you are asking about?



-Dj



-- 

Dj Merrill - N1JOV - VP EAA Chapter 87

Sportsman 2+2 Builder #7118 N421DJ - http://deej.net/sportsman/

Glastar Flyer N866RH - http://deej.net/glastar/



=================================================



On 06/10/2014 02:24 PM, Owen Baker wrote:

 	  Quote: 	
		   But there does not appear to be available an electronic directional

 indicator that would meet the 14 CFR 91.205 (d) (9) criteria for a

 “Gyroscopic directional indicator (directional gyro or equivalent)” if

 one believes that the Regulatory intended direction to be indicated must

 indeed be the current aircraft magnetic heading and not the current

 aircraft magnetic course (provided by GPS) over the surface.

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jluckey(at)pacbell.net
Guest

Posted: Tue Jun 10, 2014 3:09 pm Post subject: Direction Indicator Needs

...is simply the indication of a remotely located magnetometer (which is available for the Mini-X and Mini-AP, but not the Mini-B) then I don't think that will meet the intended requirement of 14 CFR 91.205 (d) (9) criteria for a “Gyroscopic directional indicator (directional gyro or equivalent)”....



I bet the magnetometer-driven heading indicator does satisfy the requirement.  



The reason the gyroscopic heading indicator is used is to get rid the lead/lag and dip issues associated with a magnetic compass.  The modern EFIS units & their magnetometer-based displays do not have these issues.

That's probably the reason for the "..or equivalent.." language in the reg.

-Jeff

 

     On Tuesday, June 10, 2014 3:26 PM, Owen Baker <bakerocb(at)cox.net> wrote:  

   --> Avionics-List message posted by: "Owen Baker " <bakerocb(at)cox.net (bakerocb(at)cox.net)>6/10/2014Hello Dj Merrill, Thanks for your quick response. You wrote: "....  an external magnetometer box which gives magnetic headinginformation to the EFIS."1) See here for information on what constitutes a  magnetometer:aeroelectric-list(at)matronics.com (aeroelectric-list(at)matronics.com) ; bakerocb(at)cox.net (bakerocb(at)cox.net)Subject: Re: AeroElectric-List: Direction Indicator NeedsI am not familiar with the other brands, but the GRT EFIS units comewith an external magnetometer box which gives magnetic headinginformation to the EFIS.Is that what you are asking about?-Dj-- Dj Merrill - N1JOV - VP EAA Chapter 87Sportsman 2+2 Builder #7118 N421DJ - http://deej.net/sportsman/Glastar Flyer N866RH - http://deej.net/glastar/========================On 06/10/2014 02:24 PM, Owen Baker wrote:> But there does not appear to be available an electronic directional>  indicator that would meet the 14 CFR 91.205 (d) (9) criteria for a> “Gyroscopic directional indicator (directional gyro or equivalent)” if> one believes that the Regulatory intended direction to be indicated must> indeed be the current aircraft magnetic heading and not the current> aircraft magnetic course (provided by GPS) over the surface.> http://www.matr=================http://www.matronics.com/contribution_-===================================

  

 

  

 

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