X-Virus-Scanned: clean according to Sophos on Logan.com From: "steve Izett" Received: from mail-pg0-f52.google.com ([74.125.83.52] verified) by logan.com (CommuniGate Pro SMTP 6.2c1) with ESMTPS id 9606886 for flyrotary@lancaironline.net; Fri, 24 Mar 2017 20:23:26 -0400 Received-SPF: pass receiver=logan.com; client-ip=74.125.83.52; envelope-from=steveize@gmail.com Received: by mail-pg0-f52.google.com with SMTP id t143so2545655pgb.2 for ; Fri, 24 Mar 2017 17:23:27 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=from:mime-version:subject:date:references:to:in-reply-to:message-id; bh=jqwhetIoEk8CYI4+uNcD8FhDfpqmFphg/9l1xvuM5TE=; b=Er2e6CvLQxKm1yptIVhSeBpCx6780Lm+ZDr5BhOcBfcZthc5E9/01bX1NDd6d7iRp5 vDFK3uQTbSxAfhHh6M31/WGaFl5v8X37cUpYQaoHJVYQhMzByqDrOc4Fa2rkOgqidDhY R8hlI1DPEhdh+rzost3XJ1hqVQkM3EjF3X/Dfc6Kwpq+uqdYgFMAWpQL/b7qz6HpCLzz /SPtHtgza24EPqoBQeZHf8ZMxD9ANJ0nOschOFAeWiB0umPome+uxL11X7QtpmbKNKYz f3fqMfkR+WEyw4FbXt9AVQg42eI0Pl2Rg0YQFyuTqvWfik+az8KR7hKDps3m1csUw3r9 bbyw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:mime-version:subject:date:references:to :in-reply-to:message-id; bh=jqwhetIoEk8CYI4+uNcD8FhDfpqmFphg/9l1xvuM5TE=; b=P+syV7YzYxT8InE7oidReiN1v88pGCvlDQs14929OgrxNs68/BiRQrA9nOASoruXJh okW05NbKOewc8r/1V50lT/TMGWEM+P9eQzECjLQiabcy+mm+JGOaWPBnZ5thvyOgTrj/ x4s4SEwrr/3++h7LIzgqNa3k3YcJJnZU4hwRs3icRWTJpDMm8UaCia0KWsex3w2Y5zuS IlTqFOv2EQTNwmLn+SxM2m4PnLfhJ2pyai26V2TN+KXjBVed8pUzsdRA2IrjoBQcyR+u /k0ucyGft23CNYrMOdYPjQ/nmcS0DdIfGnrButWBlHmFSzF2IqKFLPSX0jtFEV0JCulu y54g== X-Gm-Message-State: AFeK/H1NrrpgVjG9hcYXyCTop9ESjaloEafv9/Yh/stX+//xYHiYZf1Lf+lJiaVNZXsuig== X-Received: by 10.84.224.1 with SMTP id r1mr14105188plj.69.1490401390384; Fri, 24 Mar 2017 17:23:10 -0700 (PDT) Return-Path: Received: from [10.1.1.6] ([124.169.71.123]) by smtp.gmail.com with ESMTPSA id a62sm6679561pgc.60.2017.03.24.17.23.07 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 24 Mar 2017 17:23:09 -0700 (PDT) Content-Type: multipart/alternative; boundary="Apple-Mail=_17490641-7309-4A3C-BBD5-A0CA9C4FB529" Mime-Version: 1.0 (Mac OS X Mail 10.2 \(3259\)) Subject: Re: [FlyRotary] Re: Fuel Pump current and pressures Date: Sat, 25 Mar 2017 08:23:05 +0800 References: To: Rotary motors in aircraft In-Reply-To: Message-Id: <84F8D383-BBD4-4347-881A-5D8F2027E595@gmail.com> X-Mailer: Apple Mail (2.3259) --Apple-Mail=_17490641-7309-4A3C-BBD5-A0CA9C4FB529 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset=utf-8 I thought about reducing electrons but like you thought it just = introduces another failure mode to a critical path. Thanks for the feedback re mode of reducing the electrons. I could place = a series resistance to drop voltage but we would be generating a bunch = of heat. Steve > On 25 Mar 2017, at 3:36 am, Charlie England = wrote: >=20 > Good point. The GSL393 (lower volume) is what RWS (Tracy) was selling = before he retired.=20 >=20 > FWIW, I toyed with the idea of using electronic pump control (PWM) to = eliminate the need for a mechanical regulator. I called Walbro's tech = line & he said that we shouldn't use PWM (which is fine on turbine style = pumps) with gerotor pumps because the constant square wave pulsed supply = voltage 'hammers' on the gears in the pump & greatly reduces life. But = he went on to say that it's perfectly ok to run the pump at lower = voltage to reduce the flow. So it's possible to insert an adjustable DC = power supply in the supply to lower its output. Not necessarily = recommending this, since it might introduce other 'issues' (reliability = being one), but there you go.... >=20 > Charlie >=20 > On Fri, Mar 24, 2017 at 2:11 PM, Steven W. Boese = > = wrote: > Steve, >=20 >=20 > Examining the Walbro pump specifications at: >=20 > = https://walbrofuelpumps.com/walbro-gsl-series-universal-inline-fuel-pumps = and looking at the data for the individual pumps enables the following = speculation. It is only speculation. >=20 > If you have GSL392 pumps, as are almost all of the pumps listed now on = Ebay, they have a flow rating of 255 L/hr (70 gal/hr) at 40 psi and 8 = amps. If your engine could use 20 gal/hr, that would still leave 50 = gal/hr returning to the tank. With two of those pumps running at 65 psi = =20 > they should be moving 60 gal/hr each with each drawing 10 amps. If = your engine was using 20 gal/hr, 100 gal/hr would be returning to the = tank. This would seem to be moving much more fuel than necessary. = Depending on where you are measuring the fuel pressure and the details = of the fuel flow path, the pressure at the pump outlet (and the current = draw) could be much higher with flow rates this high.=20 >=20 > At these flow rates, your whole fuel system could be a constriction = and any fittings (tee's etc) may have significant effects. >=20 > That is why it would be good to establish which pumps you are using = either by identifying them or measuring their flow rates. GSL393 pumps = (45 gal/hr at 40 psi and 5 amps) might be more appropriate for your = installation if your present pumps have high flow ratings. >=20 > Steve Boese >=20 > From: Rotary motors in aircraft > on behalf of Charlie England = > > Sent: Friday, March 24, 2017 12:24 PM > To: Rotary motors in aircraft > Subject: [FlyRotary] Re: Fuel Pump current and pressures > =20 > Hey Steve,=20 >=20 > Just re-read your post with the measurements, & I'm not sure which had = higher current draw. It was the bottom pump, right? >=20 > Thanks, >=20 > Charlie >=20 > On 3/24/2017 8:06 AM, Stephen Izett wrote: >> Good idea Charlie.=20 >> That would clear it up as far as the manifold flow characteristics. >> Just a pain in the but to get to. >> Thanks >> Steve >>=20 >>=20 >>=20 >>> On 24 Mar 2017, at 8:56 pm, Charlie England = > = wrote: >>>=20 >>> Have you tried swapping the position of the pumps & making the same = measurements? It's hard to imagine it making that much difference, but = the bottom pump does have a tight right turn and then a sharp edged 'T' = turn to the left. I couldn't guess how much, but that would account for = at least some pressure increase.=20 >>>=20 >>> Charlie >>>=20 >>> On Fri, Mar 24, 2017 at 4:14 AM, steve Izett = > = wrote: >>> Hi Guys >>> Hi Peoples >>>=20 >>> Here is a photo of our parallel pumps plumbed with 3/8 aluminium = lines feed from a 28 gallon header tank above to the right. >>> Fuel then passes through the firewall and race filter before feeding = the rail and returning via the pressure regulator (4cyl toyota reg)=20 >>> back through the firewall to the header tank, again in 3/8. >>>=20 >>> I did further measurements today.=20 >>>=20 >>> 1. Bottom Pump only ~8A and 48psi - Turning both pumps on this pump = draws 9.9A and produces a rail pressure of 65psi >>> 2. Bottom Pump only ~9.9A and 44psi - Turning both pumps on this = pump draws 14.8A and produces the same rail pressure of 65psi >>>=20 >>> So bottom pump goes from 8.0 -> 9.9A (1.9A increase) under higher = head pressure >>> Top pump goes from 9.9A -> 14.8A (5.1A increase) under same head!! >>>=20 >>> Clearly Pressure Reg bypass capacity is inadequate for both pumps, = perhaps with even one pump running.=20 >>> (I don=E2=80=99t have data of fuel pressure under load to see if it = drops as power is applied) >>> I think I modelled the pump layout/manifold after seeing someone = else=E2=80=99s and not sure if it causes any problems? >>> The pumps came from eBay stating that they were genuine Walbro and = now I=E2=80=99m wondering. >>>=20 >>> Cheers >>>=20 >>> Steve Izett >>> Glasair Super II RG Renesis 4 port RD1C EC3 EM3=20 >>>=20 >>>=20 >>>=20 >>>=20 >>>=20 >>> >>>=20 >>=20 >=20 >=20 --Apple-Mail=_17490641-7309-4A3C-BBD5-A0CA9C4FB529 Content-Transfer-Encoding: quoted-printable Content-Type: text/html; charset=utf-8 I thought about reducing electrons but like you thought it = just introduces another failure mode to a critical path.
Thanks for the feedback re mode of reducing the electrons. I = could place a series resistance to drop voltage but we would be = generating a bunch of heat.
Steve
On = 25 Mar 2017, at 3:36 am, Charlie England <flyrotary@lancaironline.net> wrote:

Good point. The GSL393 (lower volume) is what RWS (Tracy) was = selling before he retired. 

FWIW, I toyed with the idea of using electronic pump control = (PWM) to eliminate the need for a mechanical regulator. I called = Walbro's tech line & he said that we shouldn't use PWM (which is = fine on turbine style pumps) with gerotor pumps because the constant = square wave pulsed supply voltage 'hammers' on the gears in the pump = & greatly reduces life. But he went on to say that it's perfectly ok = to run the pump at lower voltage to reduce the flow. So it's possible to = insert an adjustable DC power supply in the supply to lower its output. = Not necessarily recommending this, since it might introduce other = 'issues' (reliability being one), but there you go....

Charlie

On Fri, = Mar 24, 2017 at 2:11 PM, Steven W. Boese <flyrotary@lancaironline.net> = wrote:

Steve,


Examining the Walbro pump specifications at:

https://walbrofuelpumps.com/walbro-gsl-series-universal-inline-fuel-pumps

and looking at the data for the individual pumps enables the following = speculation.  It is only speculation.

If you have GSL392 pumps, as are almost all of = the pumps listed now on Ebay, they have a flow rating of 255 L/hr (70 = gal/hr) at 40 psi and 8 amps.  If your engine could use 20 gal/hr, = that would still leave 50 gal/hr returning to the tank.  With two = of those pumps running at 65 psi  

they should be moving 60 gal/hr each with each drawing = 10 amps.  If your engine was using 20 gal/hr, 100 gal/hr would be = returning to the tank.  This would seem to be moving much more fuel = than necessary.  Depending on where you are measuring the fuel pressure and the details of the fuel flow path, the pressure at the = pump outlet (and the current draw) could be much higher with flow rates = this high. 

At these flow rates, your whole fuel system could = be a constriction and any fittings (tee's etc) may have significant = effects.

That is why it would be good to establish which pumps = you are using either by identifying them or measuring their flow = rates.  GSL393  pumps (45 gal/hr at 40 psi and 5 amps) might be more = appropriate for your installation if your present pumps have high = flow ratings.

Steve Boese

From: Rotary motors in aircraft <flyrotary@lancaironline.net> on behalf of Charlie = England <flyrotary@lancaironline.net>
Sent: Friday, March 24, 2017 12:24 PM
To: Rotary motors in aircraft
Subject: [FlyRotary] Re: Fuel Pump current and = pressures
 
Hey Steve,

Just re-read your post with the measurements, & I'm not sure which = had higher current draw. It was the bottom pump, right?

Thanks,

Charlie

On 3/24/2017 8:06 AM, Stephen Izett wrote:
Good idea Charlie. 
That would clear it up as far as the manifold flow = characteristics.
Just a pain in the but to get to.
Thanks
Steve



On 24 Mar 2017, at 8:56 pm, Charlie England <flyrotary@lancaironline.net> wrote:

Have you tried swapping the position of the = pumps & making the same measurements? It's hard to imagine it making = that much difference, but the bottom pump does have a tight right turn = and then a sharp edged 'T' turn to the left. I couldn't guess how much, but that would account for at least some pressure = increase. 

Charlie

On Fri, Mar 24, 2017 at 4:14 AM, steve Izett = <flyrotary@lancaironline.net> wrote:
Hi Guys
Hi Peoples

Here is a photo of our parallel pumps plumbed with 3/8 = aluminium lines feed from a 28 gallon header tank above to the = right.
Fuel then passes through the firewall and race filter = before feeding the rail and returning via the pressure regulator (4cyl = toyota reg) 
back through the firewall to the header tank, again in = 3/8.

I did further measurements today. 

1. Bottom Pump only ~8A and 48psi - Turning both = pumps on this pump draws 9.9A and produces a rail pressure of = 65psi
2. Bottom Pump only ~9.9A and 44psi - Turning both = pumps on this pump draws 14.8A and produces the same rail pressure of = 65psi

So bottom pump goes from 8.0 -> 9.9A (1.9A increase) = under higher head pressure
Top pump goes from 9.9A -> 14.8A (5.1A increase) = under same head!!

Clearly Pressure Reg bypass capacity is inadequate for = both pumps, perhaps with even one pump running. 
(I don=E2=80=99t have data of fuel pressure under load = to see if it drops as power is applied)
I think I modelled the pump layout/manifold after seeing = someone else=E2=80=99s and not sure if it causes any problems?
The pumps came from eBay stating that they were genuine = Walbro and now I=E2=80=99m wondering.

Cheers

Steve Izett
Glasair Super II RG Renesis 4 port RD1C EC3 = EM3 





<Fuel Pres Pumps.JPG>





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