Bill,
I'm not sure what's changed, but my oil temps are up from what I reported earlier. I routinely see 220-225 on climbout, then they settle down to 200 in cruise. Maybe I'm producing more hp now, or maybe the earlier temperature report was not in mid-summer, or possibly my system is not cooling as well as it did earlier. I'm just glad that I installed TES o-rings throughout.
My cowl flap initially had an aluminum lip, that protruded into the airstream about 1". This was a quick and dirty test to see the result. I couldn't open or close it, it was open all the time. I have since replaced the 1" lip with a servo-controlled door so I can open/close as desired. When closed it is the same as a stock cowl. This is very helpful in cooler climates, not so much during triple-digit Texas summer months.
I also added an "airfoil shaped" piece on the firewall directly above the cowl flap opening. This was done in the hope of helping coax the heated air out of the cowl. But I didn't detect any great improvement in cooling. Oh, well. Next thing I plan on adding is small air dams on each end of the flap door. The idea here is to promote more efficient airflow out of the cowl flap. I've heard that these make a big difference. We'll see.
If you are considering installing a cowl flap, you may want to consider locating it on the side, or possibly install one on each side, back near the firewall. This would allow you to make the opening larger, and this location may be in a lower pressure area than the bottom, especially during climbout. Just a thought.
Cooling is still marginal in the Texas heat, and it will be worse with the new P-port 20B engine. So, I may be forced to make some major changes to get the more powerful engine to cool, or else be forced to throttle back during climbout. I've been considering relocating the radiator from under the engine to the cool side of the engine (fore/aft). This would allow me to use a slightly larger radiator. It would clean up the plumbing and significantly shorten the cooling lines too.
No, I haven't experienced SAG. But then I'm running Renesis type irridium spark plugs. I'm at 143 hours now. Personally, I won't use anything else.
Mark
On Mon, Sep 21, 2009 at 10:51 AM, Bill Bradburry <bbradburry@bellsouth.net> wrote:
Thanks Mark,
I found this msg when I was going back thru your msgs looking for your coolant and oil temps. I didn’t find anything recent and they were 195-193. What is happening now? Also I found where you got an additional 11 mph out of your cowl flap. That started me thinking…what did you change from to the cowl flap? If you just added the flap, with it closed, your configuration would be the same as before the flap…???
I plan to copy your flap, but not till I get my cooling changes done and see what happens with those before I add the extra exit opening.
Last I heard, you had about 140 hrs. Have you had any SAG yet?
Bill B
From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] On Behalf Of Mark Steitle
Sent: Monday, September 21, 2009 11:32 AM
To: Rotary motors in aircraft
Subject: [FlyRotary] Re: Progress report from Houston
I just ran a separate ground wire from one of the screws on the instrument sub-panel to the forest of tabs. It makes a lot of sense as the sub panel is mounted on a fiberglass frame, essentially insulating it from the rest of the airplane. Who knows how the ground path was completed. It probably wouldn't have hurt a thing to do the same with the other two sub panels.
On Mon, Sep 21, 2009 at 10:15 AM, Bill Bradburry <bbradburry@bellsouth.net> wrote:
Mark,
I copied the below from an msg from you last Oct.. Which pin on the PCM did you connect to ground? The only pin I can find in the instructions for the PCM that is identified as ground is pin 1 which is called out to be connected to pin 16 on the Controller? Did you splice this wire to ground or did you connect a different pin on the PCM?
“ Keep in mind that I had some data corruption problems similar to Al Gietzen. It seems to be a problem with fiberglass airplanes, so don't be surprised if you experience this too. With me, it always happened while on the ground. Last time it happened, I looked at each of the 3 tables and saw that only one was actually corrupted, so it is possible that it may have happened in the air, but since I was running above 3800 rpm (and operating in the upper table), I didn't notice any difference. Nobody really knows what causes this problem, but I seem to have fixed it by running a separate ground from the PCM to the forest-of-tabs ground. The thought was that the sub-panel was mounted on a fiberglass frame and therefore was isolated from ground. I have not had an episode since I added the ground.”
Bill B
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