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Re: Engine Cooling Fixes
Hi,
.....I straightened the tab out....
That's probably a good idea, it looked more like a spoiler than a vacuum generating device.
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Re: Engine Cooling Fixes
On the RV 7 I built we worried a lot about air leaking near the front of the engine and not going thru the cylinders. Never had oil temp or cyl temp issues but our airspeeds were much higher. I'll ask the experts at work. Cooling can be a drag (pun intended) On some of our designs we really end up spending a lot of time working on cooling issues.
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Re: Engine Cooling Fixes
The air inlet for the carb may be leaking air and affecting the pressure differential.
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Re: Engine Cooling Fixes
You really don't need a digital device to measure 5" of H2O pressure. It sure makes it nice but it isn't needed. A "slack tube" with water and a ruler would get the job done (especially if you have a helper).
Have you checked into the RV forums? I'm guessing that some of this discussion has occurred before (with respect to the cowling and airfow).
Todd
Todd Loes -- Waterloo, IA
(PA22-150 N3568Z)
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Administrator
Re: Engine Cooling Fixes
True but is kinda cumbersome in the cockpit especially in a Super Cub where I was working. Started out with an airspeed but for $60 on Amazon it has been a handy tool. Cameron, it should be there on Friday.
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Re: Engine Cooling Fixes
Originally Posted by
tloes
You really don't need a digital device to measure 5" of H2O pressure. It sure makes it nice but it isn't needed. A "slack tube" with water and a ruler would get the job done (especially if you have a helper).
Have you checked into the RV forums? I'm guessing that some of this discussion has occurred before (with respect to the cowling and airfow).
Todd
I've done a lot of searching. Seems like the stock RV fwf oil cooler is hit or miss (appears to be based on installation, but no hard data). I think that's the cooler I have.
No real issues over there with cylinder cooking unless baffling sucks.
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Re: Engine Cooling Fixes
Originally Posted by
Steve Pierce
True but is kinda cumbersome in the cockpit especially in a Super Cub where I was working. Started out with an airspeed but for $60 on Amazon it has been a handy tool. Cameron, it should be there on Friday.
Thanks Steve!
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Re: Engine Cooling Fixes
Originally Posted by
KSG
The air inlet for the carb may be leaking air and affecting the pressure differential.
I looked into that as well. It appears to be pretty tight. I can do some tightening of the seal right now but would require some fabrication to get a 100% air tight seal.
I'm planning on making a "trumpet" insert in the future to really get at a true air tight seal, but I'm hoping it's good enough for now.
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Re: Engine Cooling Fixes
Talked to Gilbert tonight and his experience the exact same baffle kit as is on my plane points to the baffles. I'm going to check with the manometer still, but I'm preemptively ordering new baffle material also. Ordering tomorrow after I measure to see if I need a 9 or 13 foot roll.
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Re: Engine Cooling Fixes
I think that when you are discussing the nature of the cooling airflow in terms of lower cowling intake air creating the pressure delta between top to bottom you all are absolutely correct. What I think you are neglecting in your discussion is that the oil cooler is a radiator device dependent on flow through it. Look at where it is mounted, first off the upper third of it is inhibited in good flow by a mounting tube, as previously discussed. and secondly it is mounted in the area that will have a downward draft of air before it reaches the cooler. The pressure air from flight is going to be drafting down to the pressure chamber outflow in the lower pressured bottom of the cowling almost immediately after it passes over the cylinder head. That section in front of the oil cooler will be diminished for air that should flow through the cooler. Now look at where the cooler is mounted, 2/3 of the cooler is in a position where the flow that does have enough pressure to flow through the cooler, it's flow through air is coming right off the top and rear fins of the cylinder. Therefore what legitimately pressurized air that might make it back through the cooler is being heated because the major surface area of the cooler is directly behind the cylinder. What air flow you are getting through the oil cooler is being heated before it actually goes through. As Gilbert indicated he worked this same problem and he mover the cooler back and it didn't help. That is completely understandable, moving it back did not do anything to augment air flow through the cooler or it's flow path that pre-heats it before it passes through the cooler. If your plane worked in Alaska and now in the lower 48 it doesn't work, the only thing that changed is the aggregate ambient air temperature, and if you used to work at really cold temperatures, and now you don't, the preponderance of evidence is that your oil cooler is being maxed out on it's ability to cool the oil by the ambient temperature it is exposed to. Anyway, I think if it were me, I would be thinking about putting the oil cooler in a place more in the path of the lower cowl inlet air flow, (even if it took building a "psuedo plenum" inside the cowling.) So, this is submitted for your consideration, as with all submitted herein, you own the lid for the "bit bucket" that you can deposit anything of your choosing into.
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