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From: "Ed Anderson" <eanderson@carolina.rr.com>
To: "'Rotary motors in aircraft'" <flyrotary@lancaironline.net>
Subject: RE: [FlyRotary] Not developing full power.
Date: Mon, 15 Jun 2009 07:40:39 -0400
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Message-Id: <20090615114034503.WSKC19023@cdptpa-omta03.mail.rr.com>

Congratulations, Don.  Always great to hear of another project airborne.

Yes, the 1.5*1.8 ratio of outlet to inlet area is a rule of thumb that has
been around a fairly long time.  Once your inlet is a certain size relative
to your radiator core then exit size becomes the dominating factor in air
flow through your system.  There is a theory which says you should narrow
your exit area in order to speed up the cooling airflow to match the
velocity of the outside airstream for minimum drag - can't recall if the
theory addressed what this did to cooling effectiveness {:>).  Always a
compromise and trade off when dealing with cooling.

Regarding your injectors, I couldn't find any size stated, but with the
stock injectors on the older 13B, you could easily fly on either pair and
produce almost full power on just two injectors.  So unless you are at the
limit of one pair then turning on/off the second pair won't make a big
difference.  Now if you are using the stock Renesis set up with the small
flow injectors for primary and large injector for secondary then it indeed
will likely make a difference.

One of the things that I have read from the experts is that the older 13Bs
were sensitive to exhaust back-pressure.  Now, I believe this is more
significant if you have radical porting of your intakes/exhaust than our
more modest intake port timing.  May also be due to the overlap of intake
and exhaust on the older 13Bs which you of course do not have with the side
port exhausts.  However, when you mention having the quietest engine on the
field makes me wonder as to whether your muffler might be impeding power
production.  Your power is, of course, going to be no better than the most
restrictive part of your intake/exhaust system.  Don't know if it's
practical (or safe) to try removing/bypassing your muffler - just to see if
it has an effect on power production.

Oops, just re-read you message and see you did remove the Hushpower muffler
- but, not certain that would make much difference as its pretty much a
straight through muffler.

You do not mention any fuel flow figures with your rpm - that would be
interesting to see - if you have the data available.  It sometimes just
takes a bit of time to develop an installation to its full potential.  The
66 mm TB should not be a limitation, I use a 65mm Mustang TB and can get
over 180 HP on my older 13B.

Keep us apprised of progress/problems/solutions

Ed Anderson

Rv-6A N494BW Rotary Powered

Matthews, NC

eanderson@carolina.rr.com

http://www.andersonee.com

http://www.dmack.net/mazda/index.html

http://www.flyrotary.com/

http://members.cox.net/rogersda/rotary/configs.htm#N494BW

http://www.rotaryaviation.com/Rotorhead%20Truth.htm

 

 

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