> >  Mike Wills wrote:

 >  >
 >  > Dick,
 >  >
 >  >   My reply was to the post from "AI Nut", not to your post.
 Unfortunately
 >  > that tidbit of info got lost somewhere along the way.
 >  >
 >  >   Regarding your seperate duct. Your installation is going into a Long
 EZ
 >  > isnt it? If correct I'd assume that available space will be at a
 premium as
 >  > it is in my "cheekless" RV-4 installation. I'm currently in the process
 of
 >  > trying to fit ducts in my cowl for rad, oil cooler, and induction air.
 This
 >  > has been some of the most time consuming and difficult work of the
 whole
 >  > project. In a tight cowl its incredibly difficult to find space for
 ducting
 >  > that fits and that is free of numerous bends, constrictions, etc... I'd
 >  > hate to have to fit another one. I wish you luck with that.
 >  >
 >  >   If the spray bar ends up being necessary for sustained climb, cruise,
 >  > etc.. then I agree it will be unacceptible. More work will be required
 >  > dialing in the basic cooling system. But for use on the ground I think
 it
 >  > is an acceptible alternative and a better choice than the fan in a
 seperate
 >  > duct. Cheaper, lighter, and much easier to fit. And since virtually
 >  > everyone that I'm aware of has struggled with initial cooling problems
 >  > during first flights I think everyone should consider installing
 something
 >  > similar before their first flight just for insurance.
 >  >
 >  > Mike Wills

 >  The new policy around here is if you want to reply to something
 >  put it at the end of the existing message and not at the beginning. That
 >  is the standard at the ACRE NL. Yes I know your email program puts
 "From:"
 >  and the cursor at the top. Just scroll down to the end
 >  of the message and place your answer or response to the now above
 >  existing message.
 >
 >  That puts things in chronological order. If you don't do this anything
 >  south of your message will be deleted.
 >
 >  Paul Lamar

 Sorry, Mike, about missing who your previous post was directed to. I read
 the other post after I had responded to yours and realized my mistake.

 Unfortunately I can't go "cheekless". My pickup scoops will all be outboard
 of the firewall. The cooler will run longitudinally through the wing root
 area above the duct. This gives me about four inches between the main duct
 and the oil pan.

 Since I won't have the big fan in front, I won't have much airflow to
 deliver the water spray to the radiator and cooler. My opinion is that fans
 are a necessity in a pusher configuration. The choice is whether to put a
 fan in the main flow and shorten its life, or find an alternative like the
 side duct. As far as the fan for the water radiator, it will be behind the
 rad. Since its cross section will be about 3 times that of the inlet, its
 airspeed will be about a third, minus the reduction from the pressure drop
 through the system. If its bearings wear out, I will just have to replace
 it. That's part of the price I pay for my choice of installation. I don't
 consider it a safety issue since it is only used on the ground, and my
 takeoff checklist includes verification of all temperatures.

 Dick Gregory

Dick,  While my installation is in a Tractor aircraft,  I have
installed fans on the  fuselage mounted radiator.  I am not the least
concerned that a free wheeling fan may eventually have bearing
problems.  If it does, I will replace it.  I have an  electric fan on
my RX-7 that has been free wheeling for more than 100,000 miles and
is still in good shape.     I don't know what your schedule is, but I
should be running this engine early next  year and   should be able
to come up with real data about what it takes to cool a 13-B on the
ground.  I think that  the fan will prove to be entirely adequate for
all ground ops.   This should allow for a  SMALLER inlet scoop.  I am
going to size mine   to become  fully effective in an airstream of
125 m.p.h. plus.  The advantage of the fan is that the engine will
not be overheating prior to starting the take-off roll.  By the end
of the runway, I will be going fast enough to no longer need the fan.
BTW,  the manufacturer of my fan, Flex-a-lite, claims that the fan
does not impede airflow through the rad when the fan is free
wheeling.   I don't know if you can believe them or not.     Jerry

One MUST run the numbers on things. A car averages 50 mph. 
The dynamic air pressure that spins the fan is FOUR times higher at
100 MPH and it is SIXTEEN SIXTEEN SIXTEEN times higher at 200 MPH!

That still does not mean the fan will live to the corresponding number 
of revolutions. If the fan is zinging along at two or three times as 
fast as it is likely to in a car it may fail in just a very few minutes
because the bearings might over heat.

Car experience is of little use when it comes to aircraft applications 
of the same parts. The absolutely amazing thing about the Mazda rotary engine
is its extraordinary and exceptional life in aircraft use compared to 
other car engines.


Paul Lamar
 
The AirCraft Rotary Engine NewsLetter.              Powered by Linux.
ACRE NL web site.
http://home.earthlink.net/~rotaryeng/            http://www.linux.org