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.I was referring to what looks like pipes intruding into the diffuser inlet from the top. What are these feeding?
Tom Giddings
Oh, I see what you mean now. Those are little scoops that feed two 1" scat tubes that feed cool air to the alternator and a plenum around the ignition coils. The cooler you keep electrical stuff the longer it lasts.
Tracy
On Thu, Apr 28, 2011 at 10:33 AM, Thomas Giddings <tom@midwestaviation.net> wrote:
Tracy: I will be mindful to never fly in front or in range of the inlet/ cannon:).... Also ..I was referring to what looks like pipes intruding into the diffuser inlet from the top. What are these feeding?
Tom Giddings
VP Avionics Sales
On Apr 28, 2011, at 10:27 AM, Tracy wrote: Tracy: What does the smaller pipe or intake do on the top of the
cowling?. I noticed this was open at Sun N Fun( I think)I am also
curious what the pipes feed inside the plenum going to the (i think
again) radiator
Tom Giddings
That is the inlet for the throttle body. It doubles as a 70mm cannon during dogfights : ) It will eventually get the same treatment as the cooling inlets.
The cooling inlets connect to the diffusers for water (on left in picture) and oil cooler (below 70mm cannon). As has been discussed at length in the past, the diffuser design is even more important than the inlets.
Tracy
On Thu, Apr 28, 2011 at 9:15 AM, Thomas Giddings <tom@midwestaviation.net> wrote:
Tracy: What does the smaller pipe or intake do on the top of the cowling?. I noticed this was open at Sun N Fun( I think)I am also curious what the pipes feed inside the plenum going to the (i think again) radiator
Tom Giddings
VP Avionics Sales
On Apr 28, 2011, at 9:07 AM, Tracy wrote: Finally got around to finishing my cooling inlets. (pictures attached) Up until now they were simply round pipes sticking out of the cowl. The pipes are still there but they have properly shaped bellmouths on them. The shape and contours were derived from a NASA contractor report (NASA_CR3485) that you can find via Google. Lots of math & formulas in it but I just copied the best performing inlet picture of the contour. Apparently there is an optimum radius for the inner and outer lip of the inlet. There was no change to the inlet diameters of 5.25" on water cooler and 4.75" on oil cooler.
The simple pipes performed adequately in level flight at moderate cruise settings even on hot days but oil temps would quickly hit redline at high power level flight and in climb.
The significant change with the new inlet shape is that they appear to capture off-axis air flow (like in climb and swirling flow induced by prop at high power) MUCH better than the simple pipes. First flight test was on a 94 deg. F day and I could not get the oil temp above 200 degrees in a max power climb. They may have gone higher if the air temperature remained constant but at 3500 fpm the rapidly decreasing OAT kept the temps well under redline (210 deg F).
I have an air pressure instrument reading the pressure in front of the oil cooler and was amazed at the pressure recovered from the prop wash. At 130 MPH the pressure would almost double when the throttle was advanced to WOT. That did not happen nearly as much with the simple pipes.
These inlets ROCK!
Tracy Crook
Homepage: http://www.flyrotary.com/
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