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al p wick wrote:
I look for root causes and systemic
failures. The "other" causes. <snip>
I'm an expert at preventing failures. Companies I managed
outperformed all of the competition. I have an obligation of every once
in a while to offer a suggestion. I expect some grief for having a
different viewpoint....although have to admit I'm appalled at this
eagerness to interpret suggestions in negative manner. -al wick
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
My marginal cooling was by no real means the cause of the incident, but a
series of not-so-smart decisions by the owner/pilot. In order to impress my friends, I found that pure water would allow the
use of more power.
Well, Al, it looks like you're not doing such a great job on this one. The root cause in this case is not technical. It can't be solved with engineering. It's a social problem cause by a need to engineer. Unfortunately, we're not dealing with an assembly plant producing an endless line of the same widget. We're dealing with a slow trickle of one-off designs, each with a builder/designer that wants to leave an impression by making an airplane that is somehow 'better' than the others. Each builder will define better in a different way...faster, lighter, cheaper, simpler, smoother, more reliable, stronger, etc. They want to create, and that is the root cause. The root cause of problems in the activity is the activity itself. The only way to solve it is to stop letting me build my own and make me buy a Cessna.
You're not getting grief for having a different opinion. The grief is for not stating an opinion. "The cooling system should have more margin" is meaningless. It may seem obvious and make you feel good to say it, but it is impossible to design to and belittles the gentlemen who ARE pouring over real numbers to pull out workable compromises toward a plane that is faster, lighter, cheaper, etc. You've been asked, and the question bears repeating, "How do you define marginal cooling?" If you can't put numbers on the design criteria then nothing can be produced to meet them, nor is there the possibility of a test to determine if it meets the criteria.
My definition for an adequate cooling system would be: An adequate cooling system should be able to maintain water temperatures of a heat soaked engine below 210 degrees F and oil temperatures below 200 degrees F through a full-power Vx climb to an altitude sufficient for a dead engine return to the airport, for any weather condition for which the pilot is likely to fly.
-The temps are somewhat arbitrary, but years of reading what other builders have had to say makes me comfortable that these are safe.
-Full-power Vx will be the worst case scenario used for the worst case takeoffs, and will differ for each airplane.
-Turnback altitude will vary for each airplane and for each pilot.
-I ain't climbing into a plastic solar oven when it's over 100 outside. Somebody will just have to settle for a call that Ernest can't make it. So there's no point in worrying if the cooling system can handle that sort of torture when I can't.
What is your definition of marginal?
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