flyrotary@lancaironline.net Mailing List Archive

"So far its looking like I could stand to shrink both inlets a little - maybe a lot. "

Mike,
Glad your EC2 & cooling issues are under control. I'd go with a cowl flap to restrict air flow (and increase exit velocity) rather than reduce inlet size. Probably less fiberglass work for the cowl flap as well.

Won't go into the mind numbing formulas and laws that govern the principal but here is what I have boiled them down to:

It is not the absolute SIZE of the cooling inlet that determines drag but the amount of air that goes through it.

Main thing is to make sure the air that is diverted around the inlet has a clean path. (you've done a good job there). Restricting the inlet will also restrict the flow but why reduce your options for other conditions (hot weather, max climb, etc).

Tracy

On Wed, Aug 19, 2009 at 11:30 PM, Mike Wills <rv-4mike@cox.net> wrote:

I seriously considered a water oil exchanger. Fluidyne also made some of those that looked really good. Dont know if they still do.

Ultimately decided not to go that route. So many people were having cooling issues when I was designing my system and it seemed that using seperate air oil exchangers would ease potential debug hassles.

I'm mostly happy with my choice. Its working well so far. And using a $25 wrecking yard RX-7 oil cooler was about as cheap as it gets. My only complaints so far are that I am not real happy with the looks of the extra scoop I added for the oil cooler, and my braided stainless oil cooler lines are fairly long and heavy.

I probably will redo the cowl somewhere down the road after I get a good handle on just how well the cooling is on hot days. So far its looking like I could stand to shrink both inlets a little - maybe a lot. On my flight the other day coolant temp never went over 180. And that included taxi from the extreme west end of the airport to the other end of an 8000' runway.

Mike Wills

RV-4 N144MW

----- Original Message -----

From: MONTY ROBERTS

To: Rotary motors in aircraft

Sent: Wednesday, August 19, 2009 6:58 AM

Subject: [FlyRotary] Re: back in the air

Mike,

Great to hear you are flying again.

I don't know if you have seen some of the new water/oil heat exchangers?. They mount in the tank of the water radiator. The preferred installation would be a dual pass water rad where the front tank is divided. The water flows through 1/2 of the radiator and gets cooled off. Then it flows through the end tank past the oil cooler picking up heat. Then it flows back through the second half of the radiator and gets cooled off again and finally gets returned to the engine. This solves the "which hose do I put the oil cooler in" dilemma. It also can greatly simplify the ductwork and make the radiator more efficient. If you are thinking about re-doing your cowl, it might solve some of your problems.

Monty

----- Original Message -----

From: Mike Wills

To: Rotary motors in aircraft

Sent: Wednesday, August 19, 2009 12:01 AM

Subject: [FlyRotary] back in the air

Finally. I'm confident that the reseat of the B controller chip solved my problem with spontaneous loss of data. I flew for 1.5 hours last friday. Engine running great and staying cool. Minor issues with the radio, landing gear shimmy on the landing, and still dont have the rudder trim right. But getting closer. Hope to get serious now about getting this thing working now that summer (and the soaring season) are winding down. Too many hobbies.

Mike Wills

RV-4 N144MW

No virus found in this incoming message.
Checked by AVG - www.avg.com
Version: 8.5.392 / Virus Database: 270.13.61/2312 - Release Date: 08/18/09 18:05:00