Cowled 2 stroke cooling question
11-10-2006, 10:05 AM
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Cowled 2 stroke cooling question
Hi All,
I was wondering if it would
I am doing final fitting of the cowl on a Goldberg Extra 300 (old BIY kit) the engine is a ST G-90 with pitts style muffler, outlet area of the cowl is huge[8D], my question is whether to open the air intake opening on the side opposite the cylinder or leave it closed, which would provide better air flow over the engine? I'm leaning towards leaving it closed, any thoughts on this?
Thanks,
Pete
I was wondering if it would
I am doing final fitting of the cowl on a Goldberg Extra 300 (old BIY kit) the engine is a ST G-90 with pitts style muffler, outlet area of the cowl is huge[8D], my question is whether to open the air intake opening on the side opposite the cylinder or leave it closed, which would provide better air flow over the engine? I'm leaning towards leaving it closed, any thoughts on this?
Thanks,
Pete
11-10-2006, 11:05 AM
#2
RE: Cowled 2 stroke cooling question
Leave it closed.
The only effective cooling on a model engine is that which blows over the top of the cylinder and head area.
However, that Pitts muffler can have a lot of heat. Try to make sure it is downstream in the airflow from the head.
The only effective cooling on a model engine is that which blows over the top of the cylinder and head area.
However, that Pitts muffler can have a lot of heat. Try to make sure it is downstream in the airflow from the head.
11-10-2006, 12:17 PM
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RE: Cowled 2 stroke cooling question
Thanks w8ye,
The muffler body is in the path of the airflow[8D]
One other question.
The fins on the head are a bit too high for the cowl, I may have to cut open the side of the cowl for the head area, rather than just a hole for accessing the plug, I'm tempted to grind down the top fins to clear, at worst I could wind up having to get a new head (I've been told I need a "checkup from the neck up"
but that's another issue) will have to check into the cost if that were the case.
Thanks,
Pete
The muffler body is in the path of the airflow[8D]
One other question.
The fins on the head are a bit too high for the cowl, I may have to cut open the side of the cowl for the head area, rather than just a hole for accessing the plug, I'm tempted to grind down the top fins to clear, at worst I could wind up having to get a new head (I've been told I need a "checkup from the neck up"
but that's another issue) will have to check into the cost if that were the case.Thanks,
Pete
11-10-2006, 12:53 PM
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RE: Cowled 2 stroke cooling question
man, DONT grind the fins.. that wouldnt be very good. you will end up burning the motor up. just trim the cowl so the head can get airflow. I know it sucks but what else can you do?
11-10-2006, 01:36 PM
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RE: Cowled 2 stroke cooling question
keep the other side closed off.
It is simple if you think about it .... physics requires the cooling air exit area to be greater than your inlet area (wont get into the math here, lets just say 3X as large). If you have the extra inlet hole, the exit area must accomodate that source of inlet air - air that is likely not performing any cooling function. With one opening, direct to the cylinder, you can be assured that the majority of the airflow is working to cool the engine and muffler, and the exit area can be sized accordingly.
Bob
It is simple if you think about it .... physics requires the cooling air exit area to be greater than your inlet area (wont get into the math here, lets just say 3X as large). If you have the extra inlet hole, the exit area must accomodate that source of inlet air - air that is likely not performing any cooling function. With one opening, direct to the cylinder, you can be assured that the majority of the airflow is working to cool the engine and muffler, and the exit area can be sized accordingly.
Bob
11-10-2006, 03:57 PM
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RE: Cowled 2 stroke cooling question
I have one of these with a 1.08 OS and a slimline pitts muffler. The engine is mounted sideways with the head protruding from the Fiberglas Specialties Cowl. Only forward facing hole is the one in front of the carb. Works fine for me.
11-10-2006, 07:42 PM
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RE: Cowled 2 stroke cooling question
Is that OS 1.08 adequate for that plane
, "In thrust we trust"
Yeh, I have the Fiberglass Specialties cowl for mine, bought the kit back in 95' when it came with that useless 2 piece plastic cowl, I also upgraded the landing gear, for what I have in it for the kit and upgrades I could buy the H9 Edge 540 ARF
ONLY KIDDING no substitute for the frustr, er, I mean satisfaction of BIY[8D]
Pete
, "In thrust we trust"Yeh, I have the Fiberglass Specialties cowl for mine, bought the kit back in 95' when it came with that useless 2 piece plastic cowl, I also upgraded the landing gear, for what I have in it for the kit and upgrades I could buy the H9 Edge 540 ARF
ONLY KIDDING no substitute for the frustr, er, I mean satisfaction of BIY[8D]Pete
