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I'm gone from time to time and sometimes miss posts. Guess I sometimes miss threads. I was of the evidently mistaken impression that the dyno tests were from a large reservoir through the engine back to the reservoir - not through any kind of realistic simulation of the cooling system in the plane.
My own partiality toward EWP stems from the fact that I've thrown some belts and anticipate throwing some more. Perhaps not on a rotary, but I can live with an electrical failure a lot better than with a coolant failure.
And it would be nice to watch PL squirm when surrounded by flying EWPs :o) ... Jim S.
Al Gietzen wrote:
Jim;
I have reported here 3 or 4 times before that I have measured the flow through my engine and the dyno cooling loop provided by the engine driven pump; and it correlates quite well with what I calculated the flow requirements to be for something near optimum for aircraft use.
We have also repeatedly been over the issue that; all other things remaining the same, the higher the flow rate the better the cooling. Lower flow simply means higher delta T, and lower average radiator temps. No, we don’t know what the minimal needs are in regard to keeping thermal stresses from being an issue in the engine.
And I agree that whether BMW wants to design for, and use, and EPW or not is irrelevant to our application, and the exchange have mostly been in the spirit of fun.
I am not “against” the use of EWPs in our airplanes. My position is simply that unless you have a “need” for configuration reasons, there is no technical reason to enter into that realm of whatever the unknowns are for this application.
Al
-----Original Message-----
*From:* Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] *On Behalf Of *Jim Sower
*Sent:* Sunday, March 20, 2005 12:41 PM
*To:* Rotary motors in aircraft
*Subject:* [FlyRotary] Re: BMW and EWP
Wasn't someone talking about the 12-16 GPM his EWP was pumping through his [not running, no EDWP] engine? Assuming 2-3 gal capacity, that circulates every bit of coolant through the system 5 or 6 times per minute. That's an entire cycle of coolant every 10 seconds or less. That sounds pretty fast to me.
Does anyone *actually know* what the flow through a rotary is with EDWP? I mean, like *measured* (the other list can be relied upon to /calculate/ stuff). Just as important, does anyone *actually know* how far open/closed a thermostat is in our applications. I know some folks don't have thermostats installed. Is it possible that EDWP might be circulating coolant so fast it doesn't have time to cool off much in the radiator or heat up much in the block? That the same system would work as well at lower flow? Or something like that?
It seems to me that all this quibbling about Beemer power levels on the autobahn ignore the obvious fact that as Leon has attested, EWP works quite well on the race tracks of Oz. I would hazard a guess that the stress on the system (WOT nearly all the time, maybe 1/3 the Q through the cooling system, SL summer temps rather than cruising much faster (3x the Q) at 80% at much higher/cooler altitudes) would hold a lot more water than a bunch of Beemer marketing brochures.
The other list is forever making pronouncements about what will or will not work. Their math is *impeccable*. The premises they operate from are *not* Is it not possible that we are overlooking or underemphasizing some important factor? That the hybrid (EWP /and/ EDWP) systems we have online now are distorting the data? Leon's experience cannot ignore any of the factors. Our estimates can ignore as many as we want to (or are unaware of). I can't help but think that a little morel hard data gathered from a purely EWP system will put a lot of the controversy to rest.
A /flawless/ line of reasoning, based on a /false premise/ leads us /right through the lookin' glass/ ...
Jim S.
Leon wrote:
----- Original Message -----
*From:* Al Gietzen <mailto:ALVentures@cox.net>
*To:* Rotary motors in aircraft <mailto:flyrotary@lancaironline.net>
*Sent:* Sunday, March 20, 2005 5:45 PM
*Subject:* [FlyRotary] Re: BMW and EWP
In a message dated 3/18/2005 11:24:08 PM Pacific Standard Time,
ALVentures@cox.net <mailto:ALVentures@cox.net> writes:
Let’s say the rated hp is at 4800 rpm. The only time you
approach rated power with this car is WOT at 4800 rpm at
sealevel on a 60F day. How long would you ever sustain that
condition.
Al
Al, How about 100mph for 20 minutes on the autoban?
Bill
Ah-h-h-h; you’re getting close now. That‘s probably about 80%
power. But you’d probably have to stop once to pay a toll, and
slow down for the Opal that’s driving in the left laneJ. Or maybe
they don’t sell the EWP version in Germany.
All
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