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

From: Perry Mick

To: Rotary motors in aircraft

Sent: Monday, September 01, 2003 8:13 PM

Subject: [FlyRotary] Re: flight #2 and #3

Rusty:

I have yet to measure the oil temp in the pan, I intend to do it so I know how well my oil
cooler is working. But 210 into the engine is gospel from Racing Beat. On my first flight oil temp
went to 240 into the engine (out of the oil cooler). This was because of inadequate airflow
through the oil cooler. With 240 in the pan you may still be ok, depending on how well
your oil cooler is working. My oil temp will still go to 220 into the engine on a hot day
during climb.

Russell Duffy wrote:

 

Thanks, but I haven't really loved it that much yet.  Maybe by the time the button gets here :-)

 

OK, below is today's installment of the log.  As you'll see, climb rpm ain't what I was expecting, and likely explains the sluggish performance.  What is the "normal" spread between static, and climb rpm for some of you guys that are flying?  

 

Also, you'll note that water temp is rock solid at 180 with the thermostat, but oil went as high as 240.  This is measured at the pan, and I assume (from Finn's data) that the return oil is probably 230 or so.  I'll be looking into an inline sensor so I can measure the temp as it goes into the engine.  Does anyone know what the safe limit for oil temp would be?  I'm running Mobile1 SuperSyn 10W-30, and their site doesn't exactly give a temp limit that I can see.  If the oil can (hypothetically) withstand routine use at 260 degrees, would the engine be harmed by running it that hot?  I've always figured that temp limits were for breakdown of the oil, but we do cool the rotors with it, so I'm sure there's some limit to what the engine will be happy with.  Just sorting through my options at this point.  

 

Anyone know of an inline temp sensor block that's available, and would have AN-10 or AN-12 fittings?  

 

Cheers,

Rusty

 

 

9-1-03  /  .6 hours  /  .7 total

Second, and I guess third flights today.  Still no fatalities, but I verified that the landing gear is pretty strong.  Gotta stop flaring this thing 5 ft off the ground. 

Flight notes.  This is with the prop set to 15 degrees of pitch, which gave 5400 rpm at 3 psi of boost static.  It’s also with a stock 180 degree thermostat.

First takeoff and climb was done at 0-1 psi, and 90 mph.  This felt about like the other day, but I couldn’t coax my anywhere map into giving me a decent VSI reading .  It appeared to be about 1000 fpm.  By most standards, this isn’t bad, but it’s not what I’m hoping for.  I was also paying too much attention to the temps to notice the rpm during climb to 2000 ft.  The water started out at 180 degrees, and never moved.  The oil started out at about 150 degrees, and reached about 220 by the time I got to 2000 ft.  I continued flying in circles at 5000 rpm and 120 mph, and the oil maxed out at 240 degrees.  This is certainly on the edge of being too high, but since I’m reading the oil pan, not the return oil from the cooler, it’s not as bad as it sounds.  More power, but higher airspeed might be a wash.  I need to try to rig an inline oil temp probe for the return oil.  The aileron trim was fine today, but that’s because the fuel was balanced, the actual trim still does nothing.  Measured the springs for replacement with stronger ones.  During descent, and landing, the oil came back down to 180 or so.  There’s also not enough up trim for landing, even with no flaps, and this thing drops like a rock with low power. 

Once on the ground, I decided to do another run around the pattern, to see what the oil temps would do with a full throttle takeoff.  Departed at 3psi of boost, and there was quite a difference in the feel of power.  Climb was still only 1500 fpm, but the real surprise was when I looked (finally) at the tach.  During climb, at 90 mph, and 3 psi of boost, I was only turning 4700 rpm.  Starting to make sense now.  I guess the prop was stalled during the static runs, so my 5400 rpm (3psi) was artificially high.  I bet I was only turning 4400 or less during the 0 psi climbs.  No wonder it seemed like a dog.  Water of course stayed rock solid at 180 degrees, but oil climbed rapidly to about 220 degrees by 1500 ft.  It’s likely that 90 mph isn’t the best climb rate for the plane, so I’ll try a little higher airspeed next time.  That will also help with the cooling. 

After the flights, I found a couple drops of oil, from those stupid POS Earl’s swivel fittings.  They’re leaking from the swivel.  I’ll NEVER buy these again.  I didn’t find anything else wrong, but I’m not sure what I’ll do about the temps, so I’ll leave the cowl off for now.  I reset the prop pitch to 12 degrees, which wasn’t exactly what I meant to do.  I thought I was on 14,  so I went down 2 degrees.  I was actually on 15, and am now down 3 degrees.  Should be just fine, since I’ve got lots of headroom on the engine rpm range to work with.  

     

-- 
Perry Mick
Custom Composite Props
mick@bridgingworlds.com
http://www.ductedfan.com