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United States, WI, Ashland
Joined Sep 2014
19 Posts
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Too all those that declare that the engine will not get the same amount of cooling on the ground as it would in the air flying, what happens to math that changes the cubic inches of air being moved by the propeller on the ground vs in the air.
volume = r x r x h x pi (sorry couldnt find the pi symbol on my keyboard.) using the formula above, 3.14 as an abreviated pi, and the prop length, 24 divided by 2 to get the radius, and pitch of 8 to determin height means 12 x 12 x 8 x 3.14 = 3,617.28 cubic inches of air is moved every time the propeller rotates. at 5000 rpms that is 18,086,400 cubic inches of air is moved every minute, that is the same if the airplane is static on the ground or if the airplane is in motion in the air. The one difference is the amount of energy exerted on the motor to move the propeller at 5000 rpms. With the airplane on the ground and no cowl on the airplane there is less restriction or blockage of the air before reaching the cooling fins on the engine cylinders, in the air with a cowl the engine is limited to how much of the air is able to reach the engine through the openings in the cowl. I myself am very reluctant to put an untested motor in a $600 airframe, start it up and take off immediately. I would rather test the motor on the ground, make sure that the tuning is spot on and stays spot on for a period of time prior to trusting that the engine has the capability of running constant straight out of the box. I regret that I did not test the motors for 3 hours each on the ground prior to flight cause had I done so both failures would have occurred while the plane was safe in the starting stand. |
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United States, WI, Ashland
Joined Sep 2014
19 Posts
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I made the trip of 103 miles to my Local Hobby Shop this morning with the engine and remnants of the Sbach. There were several veteran flyers as well as the "Engine Guy" of the hobby shop who all visually examined the motor. All noted that there was still pitting in the cylinder wall, that it was very peculiar there is no visible damage to the opposite cylinder and piston, and that the same cylinder failed on both motors.
It is not my intention to say that all DLE motors are bad, know several flyers that use DLE 20, 30, 55 55r, 111, and 120. I have yet to converse with anyone who is using the 60 twin. I hope that those who may have the 60 twin are having better luck than myself. Would much rather be flying right now than typing on here and second guessing myself that there was any part of the break in that was controllable by me to have caused the engine to seize. |
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There is an old saying "You get what you pay for". I personally would return that motor and spend the extra to get one of the quality motors that are on the market. I would also agree with the others that breaking the engine in on a stand is probably not the best idea. It's kinda like breaking in your car on jack stands. I personally beat the crap out of them right out of the box.
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I run mine once at home to make sure it'll start, to set my landing and flight idles, and to make sure transition is as I like it and my kill switch works. Then I take it to the field, crank and go fly. Running an engine incessantly on the ground is exceptionally irritating to people around you.
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United States, WI, Ashland
Joined Sep 2014
19 Posts
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I live on 60 acres, 200 acre bean field separate me from my closest neighbor.
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You might want to consider getting somone who's (more) familiar with gas powered models to help you. I've owned two DLE engines, and had no problems with them at all. While I would never put myself "out there" as being any kind of an engine expert, I just can't imagine having to run an engine for 2-3 hours on the ground prior to flying them. Not saying there would never be a reason to do this, but in my opinion it seems excessive, and I wonder if that much ground running in itself might be damaging your engines. Just my thoughts, as always YMMV. Good luck with it.
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Pitting on the cylinder wall is NOT normal or acceptable in a quality product. However, the motor appears to have been run lean, too hot, or without enough oil. The sieze is operator error though the cylinder was substandard/defective to begin with. Twins always run leaner on one side than the other. It probably would have run the warranty period with the pits but it shouldnt have them to begin with. Quality Chinese craftsmanship there. Do not break your gas motor in on the ground. Fly it a couple flights without the cowl. Get the tuning dialed in without the cowl. maybe richen it 1/8 turn and put the cowl on and check it for proper cooling and then give it the final tune. Gas motors wont quit when they are too rich but sure as heck will when they are too lean usually with a meltdown as the result as you have found out twice now...
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United States, WI, Ashland
Joined Sep 2014
19 Posts
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LHS said to follow the break in procedure according to the instructions and that is shouldnt make a difference if it is done on the ground or in the air. I chose to do it the ground at the time as the winds were 25+ with high gusts. I did have an experienced modeler working with me, he has been building rc aircraft for 40 years. Not saying he is an expert with gas engines but trust his advice when it comes to anything regarding rc flying.
I find it difficult to believe that the engine ran for hours on the ground without being to lean and as soon as it gets in the airthat it leans out and seizes. If engine was running lean it should have given the signs of a lean engine on the ground, loss of rpms after a short peoriod of time, high engine temps, lack of oil residue on firewall or starting stand. |
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We always use the lower octane gas on the DLE motors and the higher octane on the DA motors. NEVER had any issues.
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I am guessing this is your first twin, Gas engines in general can run very lean without sagging or anything at all. 280 is very hot for 40 degree weather. Breaking in it needs to at least "miss" a little at full throttle especially on a twin because of the unequal fueling between the cylinders and low crankcase pressure, probably made worse by that pitting. Also where are you measuring the temps at? The hottest spot is usually at the bottom of the fin row one above the exhaust port. The cylinder that melted had very little fuel/oil going to it. You can tell because of the color of everything especially compared to the other side. It looks new. You may consider going to a single cylinder engine for now also as they are more tolerant to tuning issues then the twin. The pitting however is not okay and i would never use a cylinder that looked like that. Last you break in period on the ground is probably causing some of the issues. Lots of things change between the ground and the air, the load is different the cowl pressure is different, rpms are higher, airflow with the cowl on is different.
As several have said before lets see some pictures of the instillation, it will revel a lot. Thanks, Kole |
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United States, TX, Fort Worth
Joined Oct 2009
12 Posts
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I also have a dle 60 and was having heating problems on the first several flights. ran good on ground and in air but after 2-3min in flight started running very badly and had to land. right cylinder was 20 to 25 degrees hotter than left, which I was told was not unusual. I opened up more cooling and put a smaller prop 22x8 on it and have 3 flights with no problems. The factory high needle setting is too lean it was more like 15/8 instead of 1 1/2. still running rich until breakin which could take a couple of gallons. good luck with a new plane
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20-30 f difference is not bad. But it is important to run it rich. Richer then you think at first. Remember your oil is in the fuel. Without fuel there is no oil and new engines need oil. Especially in most less then ideal setups.
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THATS TERRIBLE, I have never had a issue with dle always been great for me deffinetely going to check my dle 120 for any pitting when it gets here Friday
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