S3flyer Posted July 11, 2015 Report Share Posted July 11, 2015 Andy -- what was the OAT at your cruise altitude? Sometimes the air at altitude doesn't cool at a standard rate due to various atmospheric conditions. In the middle of the summer in Texas when we start our 100 degree days it sometimes stays in the 90's until 5K AGL. This is about the opposite today. Ground temp was 97 when I took off, 79 degrees at ~3K AGL and 63 at ~7K AGL. Max Oil temp for me in a continuous 13 minute climb from take-off (other than a 3 minute level off at 3500 MSL to stay out of the Dallas Class was 232F. CHT never topped 205F. Oil came down to 215-220F in 5300rpm cruise. Link to comment Share on other sites More sharing options...
FredG Posted July 12, 2015 Report Share Posted July 12, 2015 Eddie - "jpressure"? Alveoli? Not sure where you are going. I was talking about heat transfer to air. Link to comment Share on other sites More sharing options...
FastEddieB Posted July 12, 2015 Report Share Posted July 12, 2015 Eddie - "jpressure"? Oops - typo. Corrected. Alveoli? Not sure where you are going. I was talking about heat transfer to air. That's why I said it was an aside. Interesting fact, is all. Link to comment Share on other sites More sharing options...
Jim Posted July 12, 2015 Report Share Posted July 12, 2015 In addition to all the other suggestion, a weather temperature inversion will also do that. Did the cabin cool off with your gain in altitude? Link to comment Share on other sites More sharing options...
FlyingMonkey Posted July 12, 2015 Author Report Share Posted July 12, 2015 I got a chance to fly for about an hour today. I *think* my temps are okay. OAT for the flight was 75°F at takeoff, warming to about 82°F at landing. I wanted to make sure I stressed the cooling of the engine, so all climbs were done with 15° flaps at 60kt. I kept the plane low where the heat would be hardest to deal with, 3000MSL and below. All cruise was done at 5400-5500rpm to make sure things were as warm as possible. Airplane load was me (~190lb), ~28 gallons fuel, and the ~15lb of "stuff" that normally stays in the airplane. Takeoff weight was probably 1125lb to 1150lb total. Once everything fully warmed up oil temps stayed 220°F to 230°F pretty much the entire flight. It went to maybe 232°F or so briefly when I was heading back to land, when heat was highest and I was running the engine at 5500rpm, but that was the only excursion into the yellow (starting at 230°F). I reduced power a couple of miles from the airport on the 45 for downwind, and by the time I landed oil temp was 185°F, nice and cool. I consider 220°F to be the "ideal" oil temp. Not high, but still warm enough to boil off water condensation. In the winter I often have trouble getting up to that temp. So 220-230 on a warm day in high humidity at low altitude seems acceptable. Of course I'm ready and willing to hear other opinions! Link to comment Share on other sites More sharing options...
gbigs Posted July 12, 2015 Report Share Posted July 12, 2015 Morden, you are okay...when the temps get high, over 90f and add to that your humidity you will see yellow temps on Vy climbs or steeper. Once you level off, the temps will go back to the green quickly. It's normal. Remember, these little planes are not meant to do much more than fly around the patch at relatively low speeds. Link to comment Share on other sites More sharing options...
FlyingMonkey Posted July 13, 2015 Author Report Share Posted July 13, 2015 Not true. Agree. Link to comment Share on other sites More sharing options...
FastEddieB Posted July 13, 2015 Report Share Posted July 13, 2015 'Tis a poor craftsman that blames his tools. Nor sure why that came to mind! Link to comment Share on other sites More sharing options...
FlyingMonkey Posted July 13, 2015 Author Report Share Posted July 13, 2015 One thing: On my last oil change, I forgot to run the engine to warm it up before draining the oil. As a result I think the oil was a little thick and may not have drained completely. The oil level has been a little high, maybe 1/4" above the top of the dipstick flat. I don't know how, in a dry sump system like the 912 has, this could cause temps to be a little higher, but I'm mentioning it as a data point in case there is something this could affect. Link to comment Share on other sites More sharing options...
FlyingMonkey Posted July 13, 2015 Author Report Share Posted July 13, 2015 You could always do another oil change to solve that. I also thought of just draining about a half quart. Link to comment Share on other sites More sharing options...
FlyingMonkey Posted July 13, 2015 Author Report Share Posted July 13, 2015 I would do an oil change if I was concerned about the old oil. That way you can be sure to totally eliminate that nagging concern. I'm not really concerned about the old oil, the amount left after burping and draining should be small. I just don't know what the effect is of having a little more oil in the system. I have heard that you can't really "overfill" the 912 system, but I just threw it out there in case there's more to the story. I just did the oil change 5 hours ago, I don't really want to do it again, unless it's really a big deal. Link to comment Share on other sites More sharing options...
gbigs Posted July 13, 2015 Report Share Posted July 13, 2015 I'm not really concerned about the old oil, the amount left after burping and draining should be small. I just don't know what the effect is of having a little more oil in the system. I have heard that you can't really "overfill" the 912 system, but I just threw it out there in case there's more to the story. I just did the oil change 5 hours ago, I don't really want to do it again, unless it's really a big deal. You can't overfill it...it's not a sump system. too much rather than too little. 5 hours is new oil. just make sure to burp before each flight. you should have the oil between half and top of indent on stick... Notes: – Best oil is Mobil 1 MX4T motorcycle oil (also called Mobil 1 racing 4T) when using auto gas most of the time (70% or more auto-gas use) – SHELL AeroShell Sport Plus 4 should be used if AVGAS is used 30% or more of the time – Oil temp should reach 190f during flight. Oil temp of at least 212f (100C) needed to boil out moisture from oil. – Optimal operating oil temp is from 190f to 230f – Maximum operating oil temp is 266f – Higher oil weight/thicker oil is preferred for hotter climates (such as 15/50W) http://airplanepilot.sportaviationcenter.com/light-sport-planes/rotax-oil/ Link to comment Share on other sites More sharing options...
Tom Baker Posted July 13, 2015 Report Share Posted July 13, 2015 Nothing to worry about in my opinion. Unless it was still flowing pretty good it likely retained less oil in the tank than is leftin most wet sump engines. Link to comment Share on other sites More sharing options...
Doug G. Posted July 13, 2015 Report Share Posted July 13, 2015 You can't overfill it...it's not a sump system. too much rather than too little. 5 hours is new oil. just make sure to burp before each flight. you can have the oil between half and top of indent on stick...Don't you think he, and the rest of us, know that? Link to comment Share on other sites More sharing options...
Ian Posted July 13, 2015 Report Share Posted July 13, 2015 Remember, these little planes are not meant to do much more than fly around the patch at relatively low speeds. That'd be why my little aeroplane has just flown from the UK over Belgium & Holland, the length of Denmark and up through Sweden and back. Good god man you do talk some rubbish! Link to comment Share on other sites More sharing options...
FlyingMonkey Posted July 13, 2015 Author Report Share Posted July 13, 2015 That'd be why my little aeroplane has just flown from the UK over Belgium & Holland, the length of Denmark and up through Sweden and back. Yeah, don't try making the "patch flying" argument to the two fellas that flew them around the world at 1675lb gross weight. Or the other gentleman that flew from Scotland to Oshkosh. Heck, our own FastEddie flew from the TN/GA border to Page AZ in his Sky Arrow, and it has a lower useful load and "only" carries 18g of fuel! And I'm leaving for Oshkosh Saturday. I consider that outside my local patch (661nm from here). Link to comment Share on other sites More sharing options...
Tom Baker Posted July 13, 2015 Report Share Posted July 13, 2015 You can't overfill it...it's not a sump system. too much rather than too little. 5 hours is new oil. just make sure to burp before each flight. you should have the oil between half and top of indent on stick... By Rotax's own definition the oil system is a sump system. The difference is it is a dry sump system instead of a wet sump system. Link to comment Share on other sites More sharing options...
FlyingMonkey Posted July 13, 2015 Author Report Share Posted July 13, 2015 I looked at the oil hose Roger mentioned. It does make a 180° turn, but we could not find a spot where the radius looked tight enough to cause a reduced radius. I did look closely at my radiator/oil cooler. It might be slightly off center, so I might try to adjust that a little. Roger, what do you think of the temps I saw yesterday, considering the OAT? Link to comment Share on other sites More sharing options...
Roger Lee Posted July 13, 2015 Report Share Posted July 13, 2015 Hi Andy, Those temps are fairly normal for the summer months. If that's all you ever see I wouldn't lose any sleep. 210F-225F during a warm to hot summer day in cruise is normal with our particular cooler and radiator setup. (sandwiched) 225F-240F can be normal in a climb depending on flaps, speed, prop pitch and aircraft take-off weight. That 180 degree hose ought to be checked after an engine run. Feel in the bend area through the fire sleeve and see if that part of the hose feels nice and round like it does up towards the fittings or if it feels a little flattened. So far everyone I know that has placed a spring or two in the bend has had temps lowered by 10F-20F depending on how much the hose was slowing the flow (flattened). Even the guys with the thermostats have that hose just before the inlet to the oil pump and have benefited from the springs. Their bend isn't as bad as ours, but it's still there. Link to comment Share on other sites More sharing options...
FlyingMonkey Posted July 13, 2015 Author Report Share Posted July 13, 2015 Thanks Roger...what type of spring do you put in the hose, in case I get that done in the future? Link to comment Share on other sites More sharing options...
Roger Lee Posted July 13, 2015 Report Share Posted July 13, 2015 Hi LSA Flyer, You are correct that the oil here is not pressurised and if the oil was pressurised it would have a tendency to help keep the radius fully open when hot and slightly more flexible under this 180 degree bend. At that point in the hose it is a slight negative pressure over the oil tank that has the oil flowing into the pump where it gets pressurised. The oil tank is not pressurised because it has a vent to the outside atmosphere which must never be blocked or restricted. It does however have a slightly increased pressure over the oil downstream of the outlet hose which causes flow. What seems as vacuums many times is only a slight differential pressure between a slightly higher area and lower pressure area. An example is our lungs. We don't suck in air when breathing. Our chest expands and increases our lung volume which causes a slight negative pressure in our lungs over the outside pressure and then air rushes in. This is our passive everyday breathing. Link to comment Share on other sites More sharing options...
Roger Lee Posted July 13, 2015 Report Share Posted July 13, 2015 Hi Andy, If you put 1-3 springs in (depends on their lengths) then use a 1/2" stainless spring and you'll only need it where it bends. The straight parts of the hose are good. If you get serious about this call me and I'll tell you how to do it without removing the hose and losing the oil in the hose. I use a long 1/4" extension from my socket set (1/2" big end) and push it down the hose. Link to comment Share on other sites More sharing options...
FlyingMonkey Posted July 13, 2015 Author Report Share Posted July 13, 2015 Thanks Roger! I probably don't want to do this before I leave for Oshkosh Saturday, but might hop on it when I get back depending on my experiences flying up there and back. Link to comment Share on other sites More sharing options...
FlyingMonkey Posted July 14, 2015 Author Report Share Posted July 14, 2015 I made another fact finding flight yesterday. Conditions were perfect for testing temperatures: 95°F OAT on the ground, density altitude over 3200 at my 950ft elevation field. I did a climb out to 4500ft. Oil temp did get into the yellow, at about 242°F, but seemed stable there. Once I leveled at 4500ft (OAT reading 74°F), I set cruise for 5300rpm and waited for oil temp to stabilize. It came down to 230°F and stayed pretty rock stable there. At any cruise setting from 5200rpm to 5500rpm, oil temp was very stable at 228°-231°F. When I turned around to go home I reduced to 4000rpm and descended to 3500ft. When I leveled out temps were already down to 200°F. It seems like if I can fly around with no issues on a day like that, I don't have an oil temperature problem. It looks like for traveling the trick is to climb up to the cooler air ASAP. Link to comment Share on other sites More sharing options...
gbigs Posted July 14, 2015 Report Share Posted July 14, 2015 What you are seeing is normal. Link to comment Share on other sites More sharing options...
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