X-Virus-Scanned: clean according to Sophos on Logan.com From: "Charlie England" Received: from mail-pd0-f172.google.com ([209.85.192.172] verified) by logan.com (CommuniGate Pro SMTP 6.0.10) with ESMTPS id 7240839 for flyrotary@lancaironline.net; Tue, 28 Oct 2014 15:03:46 -0400 Received-SPF: pass receiver=logan.com; client-ip=209.85.192.172; envelope-from=ceengland7@gmail.com Received: by mail-pd0-f172.google.com with SMTP id r10so1299283pdi.31 for ; Tue, 28 Oct 2014 12:03:11 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=message-id:date:from:user-agent:mime-version:to:subject:references :in-reply-to:content-type; bh=5Doovx4fyqAxH+GM2lahsB4GiDIyc0IdbbJ6mn+fE0s=; b=GiaVipK0k/jtptM+96C4+v73u3yXkZRMaCQ9VVuxd37MHR1ul4KIiT3jR51b7QA2gq KZQ+C1XzFJ1LctiUrfFGswRwN7FXNUkwvGKRkqiLenM3HhqKAggcnjlPGt82rQO26533 pvffzt+E+395gopj4K4bp27Wv53nAshAu/V28Is+ryQ7Kd7mC9CZc/XiUpn1t4gY0BiS R49RLRbn/WiDA47C5SvdhvF0bdekUadonfNjn3KHN/l9D5FyWn6trhjcfPNRiCl6TedY 12Slquwd2lZPIZgRdzBUt4FVS77l54Qlj1Urc/FkQtyRG58r3VXlBSleGS1jQvzEjeNn Y+gg== X-Received: by 10.66.251.194 with SMTP id zm2mr5409242pac.33.1414522991117; Tue, 28 Oct 2014 12:03:11 -0700 (PDT) Return-Path: Received: from ?IPv6:2602:306:25fb:99:e511:72d4:a6a3:8e9d? ([2602:306:25fb:99:e511:72d4:a6a3:8e9d]) by mx.google.com with ESMTPSA id o4sm2348177pdj.2.2014.10.28.12.03.08 for (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Tue, 28 Oct 2014 12:03:10 -0700 (PDT) Message-ID: <544FE8EB.1050303@gmail.com> Date: Tue, 28 Oct 2014 14:05:15 -0500 User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:24.0) Gecko/20100101 Thunderbird/24.6.0 MIME-Version: 1.0 To: Rotary motors in aircraft Subject: Re: [FlyRotary] Re: electric fuel selector valves References: In-Reply-To: Content-Type: multipart/alternative; boundary="------------010001090603090105090703" This is a multi-part message in MIME format. --------------010001090603090105090703 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit A 'sump' tank with the pumps in it would be the best option, but difficult to achieve in a low wing plane with 'wet wing' type tanks. The bottom of an RV-x fuel tank is less than an inch above the bottom of the belly. Without a sump, the risk of sucking air is huge, when fuel levels get relatively low. Fuel *never* feeds at the same rate from both tanks to a common destination, even in high wing planes like Cessna's. On 10/28/2014 10:37 AM, Ernest Christley wrote: > Charlie, could you not provide redundancy with a on/off valve between > the tanks? If one pump dies, turning the valve on to allow fuel to > gravity flow to the tank with the good pump. Redundancy is provided > by a pump in each tank. Both run during takeoff and landing. If one > dies, switch to the other tank and run it low, then open the valve to > get fuel from the tank with the bad pump if you haven't found an > airport already. > > > > On Monday, October 27, 2014 6:46 PM, Charlie England > wrote: > > > On 10/27/2014 4:55 PM, Ernest Christley wrote: >> This is the type that I'm referring to: >> >> http://products.pollakaftermarket.com/item/fuel-selector-valves/light-truck-6-port-motor-driven-valve/42-302 >> >> >> On Monday, October 27, 2014 5:50 PM, Ernest Christley >> wrote: >> >> >> Is anyone familiar with electric fuel selector valves as used in >> automotive applications. I'm trying to figure out how they operate. >> Do they select one line when power is applied to a solenoid type >> plunger, and then the other line is selected when power isn't >> applied? Or does a pulse of power switch them back and forth? If >> they maintain the currently selected tank when power is absent, it >> seems to me that this could remove fuel lines and a leak prone >> selector valve from a lot of cockpits. Furthermore, the 6 port models >> look like they could be plumbed easily to handle return lines. >> >> >> > The ones I've seen actually use a motor to move the valve (think screw > jack), so they will remain in last position. Reading your linked item > indicates that it works the same way. > > 'Traditional' engine guys have avoided them in the past because > they're plastic and they require power (and they are an automotive > product, so they can't be reliable ;-) ). They are probably worth > considering, but I'm seriously looking at switching to in-tank turbine > pumps with automotive style PWM control; no return line needed. Then > tank selection would be with a switch on the panel instead of a valve. > Downside is that for total redundancy, I'd need 2 pumps in each tank. > They are dirt cheap (<$20 each), but controllers are around $75 ea and > switching gets pretty elaborate if there are more than 2 tanks. > > Charlie > > --------------010001090603090105090703 Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit
A 'sump' tank with the pumps in it would be the best option, but difficult to achieve in a low wing plane with 'wet wing' type tanks. The bottom of an RV-x fuel tank is less than an inch above the bottom of the belly. Without a sump, the risk of sucking air is huge, when fuel levels get relatively low. Fuel *never* feeds at the same rate from both tanks to a common destination, even in high wing planes like Cessna's.

On 10/28/2014 10:37 AM, Ernest Christley wrote:
Charlie, could you not provide redundancy with a on/off valve between the tanks?  If one pump dies, turning the valve on to allow fuel to gravity flow to the tank with the good pump.  Redundancy is provided by a pump in each tank.  Both run during takeoff and landing.  If one dies, switch to the other tank and run it low, then open the valve to get fuel from the tank with the bad pump if you haven't found an airport already.



On Monday, October 27, 2014 6:46 PM, Charlie England <flyrotary@lancaironline.net> wrote:


On 10/27/2014 4:55 PM, Ernest Christley wrote:
This is the type that I'm referring to:

http://products.pollakaftermarket.com/item/fuel-selector-valves/light-truck-6-port-motor-driven-valve/42-302


On Monday, October 27, 2014 5:50 PM, Ernest Christley <flyrotary@lancaironline.net> wrote:


Is anyone familiar with electric fuel selector valves as used in automotive applications.  I'm trying to figure out how they operate.  Do they select one line when power is applied to a solenoid type plunger, and then the other line is selected when power isn't applied?  Or does a pulse of power switch them back and forth?  If they maintain the currently selected tank when power is absent, it seems to me that this could remove fuel lines and a leak prone selector valve from a lot of cockpits.  Furthermore, the 6 port models look like they could be plumbed easily to handle return lines.



The ones I've seen actually use a motor to move the valve (think screw jack), so they will remain in last position. Reading your linked item indicates that it works the same way.

'Traditional' engine guys have avoided them in the past because they're plastic and they require power (and they are an automotive product, so they can't be reliable ;-)  ). They are probably worth considering, but I'm seriously looking at switching to in-tank turbine pumps with automotive style PWM control; no return line needed. Then tank selection would be with a switch on the panel instead of a valve. Downside is that for total redundancy, I'd need 2 pumps in each tank. They are dirt cheap (<$20 each), but controllers are around $75 ea and switching gets pretty elaborate if there are more than 2 tanks.

Charlie



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