ryan_m
100cc
I've been running a motor with no spinner for a while now, it's mounted on a 3dhs 91" Yak 55. The cowl curves around the front more than most other Yak's I've seen, and if I used the 3dhs suggested spinner (4") it doesn't leave a whole lot of room for air to enter the cowl and cool the motor, especially if it's baffled. There is about 3/4" gap between where the edge of the spinner and the edge of the cowl are. So I've left a spinner off and figured the motor would get more air over it this way. I've got another thread on here somewhere asking about motor temps, and how hot is ok, and right now I'm in the ok range (330 degrees max with temp sensor mounted at back/top of one of the cylinders). But it hasn't gotten into summer heat yet, and the plane has only been flown in 70-75 degree temps, not the 100 degrees we often see here in the summer. And I have an alarm setup when it hits 325, so I can back out of whatever maneuver I'm in and let it cool down. It is interesting to see how quickly a motor heats up and cools down with the telemetry readings on various moves.
Anyways, a full scale pilot was looking the plane over and suggested that a spinner would actually really help cool the motor better. He said there is a nasty turbulent area right in front of the prop from the flat plate/prop bolts that are exposed there and that a spinner would actually help it run cooler despite appearing to allow much less airflow since the air would flow right in smoothly. He said that on one of his full scale planes he can't even fly the motor without a spinner as the motor overheats rapidly. So it's got me thinking I should add a spinner, but I don't want to spend 50-100 bucks to try one only to find it doesn't help at all.
So what do you guys think? Will a spinner help any? The motor is an EME70 twin. Thinking if I did do a spinner that it should be a 3.5" one, not a 4". What is everybody's preferred brand of spinner if I do add one?
Anyways, a full scale pilot was looking the plane over and suggested that a spinner would actually really help cool the motor better. He said there is a nasty turbulent area right in front of the prop from the flat plate/prop bolts that are exposed there and that a spinner would actually help it run cooler despite appearing to allow much less airflow since the air would flow right in smoothly. He said that on one of his full scale planes he can't even fly the motor without a spinner as the motor overheats rapidly. So it's got me thinking I should add a spinner, but I don't want to spend 50-100 bucks to try one only to find it doesn't help at all.
So what do you guys think? Will a spinner help any? The motor is an EME70 twin. Thinking if I did do a spinner that it should be a 3.5" one, not a 4". What is everybody's preferred brand of spinner if I do add one?
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