Mailing List flyrotary@lancaironline.net Message #2909
From: Tracy Crook <lors01@msn.com>
Subject: Re: Turbos & EM2 Survey
Date: Fri, 12 Sep 2003 11:41:23 -0400
To: Rotary motors in aircraft <flyrotary@lancaironline.net>
Message
Really good discussion of 'real world' factors on aircraft turbocharging for the past few days.  
 
Rusty's brief comment about fuel burn on boost is especially relevant.  I get frequent inquiries about reliability when running 'conservative' manifold pressures of 30 - 40" Hg at cruise.   The engine would probably tollerate this but the ignored factor is fuel burn.  A standard RV-3 (with the original internal fuel tank) would have less than 1 hour endurance when running at 40" MAP.  At max power my RV-4  only has a 1.5 hour endurance at sea level (30" MAP) and I don't have a turbo!.   
 
This is not an argument against turbos, in fact I may soon have 'turbo envy'  when these guys get them operational. There are reasons why a turbo can be a good thing, just be sure you know what they are.
 
But the real reason for this post is to get an idea of what size EM2 display would have the highest demand.  I'm ordering the parts for the first production batch next week and software development is 99% complete.  
 
The EM2 will be available in two different sizes but both have all the same other features.  The large format has a panel cutout width the same size as a standard radio stack  (6.2") with mounting flange out to 6.5".   Total heigth is 2.875"  with a cutout heigth of 2.5".
 
There are a lot of planes already out there with very little panel space left so the smaller version would suit them better.  The EM2-S measures 4.7" wide x 2.55" tall with a panel cutout window of about 3.5" x 2".The price for the smaller format is slightly lower but not enough to make that a big factor.
 
So, the question is, which would most pilots want?  Any answer or guess is welcome. 
 
Thanks to all for the encouragement (& patience!) on this project.
 
Tracy
 
PS:
For an example of  what took so long, I just spent a week programming & optimizing the damping factor for altimeter & VSI functions.  Stuff like this didn't even occure to me when I started.  I saw the need when static port pressure burbles due to turbulent airflow, wind gusts, etc would send these readings all over the place. 
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