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Hi Ed,
I have no actual experience with a oil/coolant heat exchanger. I looked at them and decided that since I had room for an oil cooler (and already owned one) that a oil/coolant heat exchanger would not provide any benefit. Theoretically, the heat transferred from the oil to the coolant raises the temperature of the coolant compared to the incoming cooling air - thus making that arrangement thermodynamically more efficient due to the increased temperature difference. On the other hand, this is somewhat offset by the fact that by raising the temp of the coolant the temperature difference between the oil and its cooling agent (the water) will be lessened. Which in turn is offset by the fact that a lb of water can carry more heat than a lb of air {:>).
However, I think the main advantage of the oil/coolant heat exchanger is:
1. Give you more freedom in installation in that you can put the exchanger just about anywhere without worrying about how to get cooling air to it.
2. Eliminates the need for a separate oil cooler
Since you are dumping the oil heat into the coolant this will generally necessitate a large radiator system to handle the additional heat load.
Since I have no experience with the units, I am unaware of their most common failure mode. Personally, a case could be made that without airflow to an oil cooler you are better protected against rocks ect, damaging it. If you have a leak in the lubrication system your engine is going to seize sooner rather than later. Leaks in the coolant system will result in engine damage but at least two case shows that the overheated engine will still continue to function well enough, long enough to get you to a safe landing.
I think your NASCAR contact can probably provide better input on the pros and cons of using one.
Ed
----- Original Message ----- From: "Ed Klepeis" <techwelding@comcast.net>
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
Sent: Sunday, April 29, 2007 10:06 PM
Subject: [FlyRotary] Re: oil coolers
Dear Ed
What is your opinion on oil coolers air/oil or water/oil. I know art is running a water cooler oil cooler and it works fine my concerns are if you should lose water cooling there goes the whole system water and oil. At least if you have your oil cooling system air cooled you have some cooling of the eng to get you safely on the ground. Also less lines to hook up without the water going to the oil cooler.I have a meeting with my neighbor Waltrip the nascar fellows cheif mech to talk this subject over will be interesting to see what the nasca boys say and use. I can build it either air/oil or water/oil. What are the opinions out there.thanks
Regards
Ed Klepeis
----- Original Message ----- From: "Ed Anderson" <eanderson@carolina.rr.com>
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
Sent: Sunday, April 29, 2007 7:26 PM
Subject: [FlyRotary] Re: Throttle body size
Hi Buly,
I have tired throttle bodies as big as 75mm, I went back to a 65 mm Mustang Throttle body. Here is what I found.
The larger throttle body provided no measurable increase in power produced - in fact, the power actually went down as my static fell 200 rpm. I did find that suddenly opening the large 75mm TB would cause the engine to bog and hesitate for a second. It was suggested that I push the throttle in more slowly, well, Scotty, when I want full power I want it NOW!
In any case, I now fly and have flown with the 65 mm for 3 years. I can turn 6000 rpm static on a standard day and upto 6200 static on those wonderful cold mornings. I can shove the throttle in as fast as I can and there is no bog or hesitation.
That is what my experience has been. For a full up all out race engine, I am certain Paul's suggestion has merit, but for our usage, I did not find a large TB provided any improvement and actually make flying less pleasant.
Ed
----- Original Message ----- From: "Bulent Aliev" <atlasyts@bellsouth.net>
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
Sent: Sunday, April 29, 2007 6:05 PM
Subject: [FlyRotary] Throttle body size
I originally planned and tried TA set up on my Cosmo 13B. Soon after the first few flights removed the turbo and vent NA. At the time did not pay much attention on the throttle body size, counting on the turbo to make up for any losses. Today I measured the inside opening of the TB and was surprised to find it was only 60mm. This is rather small. Paul Lamar on his visit also said I should get a bigger one. I wander what size TB other people are using, or any comments and suggestions on the matter will be helpful.
Buly
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