flyrotary@lancaironline.net Mailing List Archive

My memory finally kicked in. I was using was the Meziere WP337S rated at 55 GPM, so you can see that flow rates are much lower than the spec once installed in the system. I still don't know where my flow tests data is. I seem to recall the "free flow" that I measured as being more like 20 GPM. Bob W. On Sun, 27 Apr 2008 12:48:52 -0400 "Ed Anderson" <eanderson@carolina.rr.com> wrote: > Thanks for the report, Bob. I suspected that the flow rates were based on > best - obtainable (no flow restrictions). But, even so and as suggested by > your experience (marginal cooling) EWP may not provide the best answer. OR > perhaps a different EWP (they do seem to vary quite a bit in claimed flow > rate and power consumed) might provide the answer. > > Will be interested to see how it works out in your car. > > Ed > ----- Original Message ----- > From: "Bob White" <bob@bob-white.com> > To: "Rotary motors in aircraft" <flyrotary@lancaironline.net> > Sent: Sunday, April 27, 2008 12:40 PM > Subject: [FlyRotary] Re: Electric Water pumps - Interesting > > > > Hi Ed, > > > > I did some testing on the EWP's. The rating is the free flow rating, > > but my measurements seemed to indicate that number was overly > > optimistic. I will have to dig around to see if I can find the stuff I > > did on it. With just a short hose on the inlet and outlet plus a flow > > meter, I got substantially less flow. The 3.8 hours I flew was with > > the EWP exclusively. As I recall, the in system flow rate was around > > 10 gpm. Using calculations based on Bill Shertz' work I had wanted 15 > > GPM. > > > > The 3.8 hours I flew was in 50F to 60F temps and cooling was adequate > > but marginal. I believe I had seen 220 on the oil temps once in > > climb. Water temps were a little lower. When I leveled off and pulled > > the power back, temps would drop below 200 pretty quickly. I know the > > air flow through my oil cooler was poor, and was on my short list to > > modify. Air flow through the radiators may not have been as good as > > it could have been either. > > > > Now let me propose a theory as to why the simple argument that the EWP > > wont work because it doesn't consume enough HP may be incorrect. The > > stock pump on the engine definitely uses 5 to 10 HP. But does it > > need to? The stock pump has to provide adequate cooling sitting at a > > stop light in 120F temps (Phoenix in the summer). HP goes up as the > > second or third power of RPM (one of the things I need to look up > > again). So to get adequate cooling flow at idle, the cooling flow at > > cruise may well be more than adequate. As mentioned earlier, I had > > calculated that I needed 15 GPM. The air flow needed to be sufficient > > to give the delta T's I was using in the calculation. The EWP has the > > advantage of providing full flow at all speeds, so the use in a car > > seems quite doable since there are very few times full power is > > sustained for any length of time. > > > > This is all just a theory, and it's not a theory like the "Theory of > > Gravity". It's the hypothesis kind of theory. > > > > I will be using the exact same setup in the Alpine with the EWP. I > > will at least be able to report on how well it does in the car. > > > > Bob W. > > > > > > > > On Sun, 27 Apr 2008 10:31:47 -0400 > > "Ed Anderson" <eanderson@carolina.rr.com> wrote: > > > >> I was just thumbing through a recent catalog from Summit Racing and came > >> across a couple of pages on electric water pumps. There has always been > >> a degree of interest (and some debate {:>)) regarding the use of electric > >> water pumps in aircraft. It was interesting to read some of the > >> descriptions, but basically the current consumed ranged from 4 - 9 amps > >> and the quoted flow rate (presumably without back pressure) was from > >> 16-35 gpm. > >> > >> So if you take 9 amps at say 14 volts = 126 watts = 0.167 HP to get that > >> flow. However, some of them indicate you can save 15 - 20 engine HP at > >> HIGH rpm. So why the difference? > >> > >> Apparently (my best guess) is that they are advertising their product > >> to best advantage (surprise?). I would suspect that the flow rates shown > >> are without back pressure and that when attached to a real engine coolant > >> system that : > >> > >> 1. The flow rates would decrease > >> 2. The current requirements would increase. > >> > >> However, not to the point the electric pump would be required to make > >> 10HP or more to provide the required flow. I suspect there are > >> considerable losses (such as pump cavitation and pressure drops through > >> the cooling galleys)with mechanical pumps at high pump rpm as driven by > >> a high revving engine which accounts for the high power requirements. > >> Whereas the electric driven pumps may operate at lower and more efficient > >> rpm without the majority of those losses. > >> > >> That said, the pumps cost range from around $200 - $400 and while no > >> weights were given, basic on the photographs showing the heavy electric > >> motors and additional plumbing would not appear to offer any significant > >> weight savings over the proven, reliable mechanical pumps most of us are > >> using. > >> > >> So while certainly interesting and perhaps of value in some aircraft > >> installations(how would you like to gain an additional 10 HP on > >> takeoff?), I remain confident in my old 86 13B water pump housing and > >> cartridge which is still going strong after 10 years. I have moved it > >> from my first 86 N/A engine to my current 91 turbo block, so it has > >> performed for over 10 years in two different engines without any problem. > >> > >> Interestingly, of the 11 electrical water pumps advertised, only one > >> was specified for drag race use only - and it had the lowest current > >> drain - 3.5 amps. > >> > >> Ed > >> > >> Ed Anderson > >> Rv-6A N494BW Rotary Powered > >> Matthews, NC > >> eanderson@carolina.rr.com > >> http://www.andersonee.com > >> http://members.cox.net/rogersda/rotary/configs.htm#N494BW > >> http://www.dmack.net/mazda/index.html > > > > > > -- > > N93BD - Rotary Powered BD-4 - http://www.bob-white.com > > 3.8 Hours Total Time and holding > > Cables for your rotary installation - http://roblinstores.com/cables/ > > > > -- > > Homepage: http://www.flyrotary.com/ > > Archive and UnSub: > > http://mail.lancaironline.net:81/lists/flyrotary/List.html > > > > > -- > Homepage: http://www.flyrotary.com/ > Archive and UnSub: http://mail.lancaironline.net:81/lists/flyrotary/List.html -- N93BD - Rotary Powered BD-4 - http://www.bob-white.com 3.8 Hours Total Time and holding Cables for your rotary installation - http://roblinstores.com/cables/