X-Junk-Score: 0 [] X-Cloudmark-Score: 0 [] X-Cloudmark-Analysis: v=2.3 cv=BpPjPrf5 c=1 sm=1 tr=0 a=2tOgoP+HbBZfdd6ybCl50g==:117 a=B8PDgl8qUVeOwhCkz8FinA==:17 a=jpOVt7BSZ2e4Z31A5e1TngXxSK0=:19 a=x7bEGLp0ZPQA:10 a=A-0mRrAPPO4A:10 a=Jdjhy38mL1oA:10 a=r77TgQKjGQsHNAKrUKIA:9 a=3oc9M9_CAAAA:8 a=HZJGGiqLAAAA:8 a=Ia-xEzejAAAA:8 a=on22okXAAAAA:8 a=pGLkceISAAAA:8 a=7g1VtSJxAAAA:8 a=IJtCpeALRtIu7_KFm3kA:9 a=QEXdDO2ut3YA:10 a=Py9Ta2HYjrcA:10 a=NALRNPPH8BMA:10 a=Qa1je4BO31QA:10 a=gvSQh4r-fQ0A:10 a=4PR2P7QzAAAA:8 a=W53kHm5dq2c4doR5b34A:9 a=hb-Lg6IkLjgGEyqS:21 a=_W_S_7VecoQA:10 a=Urk15JJjZg1Xo0ryW_k8:22 a=NPqpj5bUEVj9vR1HIonK:22 a=grOzbf7U_OpcSX4AJOnl:22 a=4dqwQCo7Po2mVW515mGf:22 From: "Charlie England ceengland7@gmail.com" Received: from mail-yb1-f181.google.com ([209.85.219.181] verified) by logan.com (CommuniGate Pro SMTP 6.2.14) with ESMTPS id 13408295 for flyrotary@lancaironline.net; Mon, 20 Jan 2020 19:33:48 -0500 Received-SPF: pass receiver=logan.com; client-ip=209.85.219.181; envelope-from=ceengland7@gmail.com Received: by mail-yb1-f181.google.com with SMTP id p129so572922ybc.13 for ; Mon, 20 Jan 2020 16:33:49 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=subject:to:references:from:message-id:date:user-agent:mime-version :in-reply-to:content-language; bh=VABLH63eyh3TkPuxOMPlRqwCHu8O5GpGnmf4RZAdDQw=; b=IdlmCD5A/ASPf7WubtQS1QGXstSPcYJSPEyKWWdsYIPgSvZKwGfbKg3s67aIN1eCpM GBuemTD2IsU+jGdoZhY/2AoegdF9xfqapmu2YEuHWT5Z1Weoh1QjWR/NHtK+YbCWH3Cu fAoIzCgkWY6oUZbziUDGcQNo7J7BskVAVNum/9DdVA0oDRD7B8qmcwcuOCJwu6ekTuT/ 7gmRzsojbTBf81yPt96M3Hc8mgUV5T+e1cpCEKn74yjYfB6gIXhJBe85AZvDVixZI2N4 EPpe/I8WdgDONOdGgXiUCHeq9ITyMi/to8IGMzSm9pJGpimwFDDcCu0xIiZ7+yDWBE/k 3ukg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:to:references:from:message-id:date :user-agent:mime-version:in-reply-to:content-language; bh=VABLH63eyh3TkPuxOMPlRqwCHu8O5GpGnmf4RZAdDQw=; b=apGX/lpYPapG04L8+KU/xgz+j1eOHDP0wE7AZHC/uzZts0PfJjhuYBzObmkmZcVeAW OppSm4BvgLmO/cycDpa3F1x9dIi1pvn/JRomC+4l4ob5IxN0hzaVAU1HBbIS2oLbroTi Q3Xtzij2W7llz/yYCEERvMO/KamV7Cdvk/AFu/fRPdvV3v+Hw1sM9Kpe5rETO0bhayMW ywTDfZAyZNgoRoKpAyil0w0lpfnwMSKT1mzNwosy+hoKT2Cwp2f9uDOs80o8eGykNb0f 21EpiTUo+X7QHus2pnreCP8SBG3+WE1QL2kb+6/+xFuoQ5CEnljlUKksGKlhPc5CnEyB Ixhg== X-Gm-Message-State: APjAAAWZ1wN+GuLmujBQiXVIV2oE40txJJ/N4t+HYlUlKEhZGzBI1mtp gLYQiN5izzKrtOQudu9GUQMuxoKq X-Google-Smtp-Source: APXvYqxr/33qwsZ1Q7g2IvE/e8hI8w9rVPyBLgOlLevKc5fl7zo5Yf+kGRi86Mn+YivFR52hOrr0tw== X-Received: by 2002:a25:c0cf:: with SMTP id c198mr1676594ybf.135.1579566812694; Mon, 20 Jan 2020 16:33:32 -0800 (PST) Return-Path: Received: from [192.168.10.246] (mobile-166-170-55-124.mycingular.net. [166.170.55.124]) by smtp.googlemail.com with ESMTPSA id y129sm16307593ywd.40.2020.01.20.16.33.30 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 20 Jan 2020 16:33:31 -0800 (PST) Subject: Re: [FlyRotary] Re: Fuel System Design for High wing Aircraft To: Rotary motors in aircraft References: Message-ID: <5694ab12-8230-e3f1-2f39-f35f0f5f23d5@gmail.com> Date: Mon, 20 Jan 2020 18:33:31 -0600 User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:68.0) Gecko/20100101 Thunderbird/68.4.1 MIME-Version: 1.0 In-Reply-To: Content-Type: multipart/alternative; boundary="------------BFC24B301F4EEF58F26D8E7F" Content-Language: en-US X-Antivirus: Avast (VPS 200120-2, 01/20/2020), Outbound message X-Antivirus-Status: Clean This is a multi-part message in MIME format. --------------BFC24B301F4EEF58F26D8E7F Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit The pumps most of us use (Walbro GSL393, etc) are positive displacement. For a given rpm, they will output a fixed quantity of fuel, which can't be compressed in any meaningful way. That means that the only way to control volume is by either slowing the pump's rotation, or bypassing excess fuel. Slowing the pump via pulse width modulation (PWM), which maintains full torque (pressure) at varying rpm, will damage the pumps, according to Walbro. I suspect that slowing the pump via reduced analog voltage would be a difficult endeavor, since pump torque will fall off very quickly as voltage is reduced. Charlie On 1/20/2020 5:25 PM, argoldman@aol.com wrote: > My understanding is that the volume of fuel spurted, by the injector,  > is related to the time the injector is open and the fuel pressure. My > guess is that the pumps vary slightly in pressure as they run thus > each shot-o-fuel would be different based on the variable pump outlet > pressure yielding an unsteady mixture. > > There are probably some pressure regulators that are sensitive enough > not to need a return line. Anybody know of such a beast? > > Rich > > > -----Original Message----- > From: Ernest Christley echristley@att.net > To: Rotary motors in aircraft > Sent: Mon, Jan 20, 2020 4:23 pm > Subject: [FlyRotary] Re: Fuel System Design for High wing Aircraft > > Does the fuel necessarily have to be returned?  What is the benefit of > returning it? Injectors can take 50lbs of pressure.  In fact, they > make a better spray with the higher pressure, and atomize even better > if the fuel is sprayed hot.  Many modern cars don't have a return.  As > long as you keep the pumps  and the gas going to them cool, you won't > get vapor lock. > > Keep the fuel pump below the injectors and behind the firewall.  It'll > draw cool fuel and then pressurize it to keep it liquid until it is > sprayed.  On shutdown, the fuel in the line firewall forward will get > hot and vaporize, pushing liquid back to the pump.  But, as soon as > the pump is flipped on the vapor gets compressed and liquified again > for the rest of its time in the line. > > I could be wrong. . . > > On Monday, January 20, 2020, 10:43:07 AM EST, Jeff Whaley > jwhaley@datacast.com wrote: > > > Hi Bobby, yes Ed used a small (1 qt) can attached to the engine-side > of the firewall, to accept main fuel IN, return fuel and parallel > outputs to his fuel pumps.  This system would work regardless of wing > arrangement but I'm not too sure how it performed at keeping LOW fuel > temperatures. > > My high-wing has a 2 gallon header tank on the cabin-side of the > firewall, so I Tee'd my fuel return into one of its two vent lines > that connect back to the wing tanks.  This is a gravity-fed system > until it passes through the firewall to the pumps ... the vent lines > assist in draining the tanks evenly. > Jeff > > What is the best method for handling return fuel in a high wing? Fuel > return to a small header tank sized to keep fuel temperatures low? I > think Ed Anderson may have used a small header in his RV6. > > Asking for a friend with an airplane addiction. > > Bobby > > -----Original Message----- > From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net > ] > Sent: January-20-20 6:01 AM > To: Rotary motors in aircraft > Subject: flyrotary Digest #4865 > >         Rotary motors in aircraft Digest #4865 > > 1) Re: Mufflers >     by "Neil Unger 12348ung@gmail.com " > > > 2) Re: Mufflers >     by "Charlie England ceengland7@gmail.com > " > > > This digest is sent to you because you are subscribed to >   the mailing list >. > To unsubscribe, E-mail to: > To switch to the FEED mode, > E-mail to > > Send administrative queries to  > > > > -- > Homepage: http://www.flyrotary.com/ > Archive and UnSub: > http://mail.lancaironline.net:81/lists/flyrotary/List.html --------------BFC24B301F4EEF58F26D8E7F Content-Type: text/html; charset=utf-8 Content-Transfer-Encoding: 8bit
The pumps most of us use (Walbro GSL393, etc) are positive displacement. For a given rpm, they will output a fixed quantity of fuel, which can't be compressed in any meaningful way. That means that the only way to control volume is by either slowing the pump's rotation, or bypassing excess fuel. Slowing the pump via pulse width modulation (PWM), which maintains full torque (pressure) at varying rpm, will damage the pumps, according to Walbro. I suspect that slowing the pump via reduced analog voltage would be a difficult endeavor, since pump torque will fall off very quickly as voltage is reduced.

Charlie

On 1/20/2020 5:25 PM, argoldman@aol.com wrote:
My understanding is that the volume of fuel spurted, by the injector,  is related to the time the injector is open and the fuel pressure. My guess is that the pumps vary slightly in pressure as they run thus each shot-o-fuel would be different based on the variable pump outlet pressure yielding an unsteady mixture.

There are probably some pressure regulators that are sensitive enough not to need a return line. Anybody know of such a beast?

Rich


-----Original Message-----
From: Ernest Christley echristley@att.net <flyrotary@lancaironline.net>
To: Rotary motors in aircraft <flyrotary@lancaironline.net>
Sent: Mon, Jan 20, 2020 4:23 pm
Subject: [FlyRotary] Re: Fuel System Design for High wing Aircraft

Does the fuel necessarily have to be returned?  What is the benefit of returning it?  Injectors can take 50lbs of pressure.  In fact, they make a better spray with the higher pressure, and atomize even better if the fuel is sprayed hot.  Many modern cars don't have a return.  As long as you keep the pumps  and the gas going to them cool, you won't get vapor lock. 

Keep the fuel pump below the injectors and behind the firewall.  It'll draw cool fuel and then pressurize it to keep it liquid until it is sprayed.  On shutdown, the fuel in the line firewall forward will get hot and vaporize, pushing liquid back to the pump.  But, as soon as the pump is flipped on the vapor gets compressed and liquified again for the rest of its time in the line.

I could be wrong. . .

On Monday, January 20, 2020, 10:43:07 AM EST, Jeff Whaley jwhaley@datacast.com <flyrotary@lancaironline.net> wrote:


Hi Bobby, yes Ed used a small (1 qt) can attached to the engine-side of the firewall, to accept main fuel IN, return fuel and parallel outputs to his fuel pumps.  This system would work regardless of wing arrangement but I'm not too sure how it performed at keeping LOW fuel temperatures.

My high-wing has a 2 gallon header tank on the cabin-side of the firewall, so I Tee'd my fuel return into one of its two vent lines that connect back to the wing tanks.  This is a gravity-fed system until it passes through the firewall to the pumps ... the vent lines assist in draining the tanks evenly.
Jeff

What is the best method for handling return fuel in a high wing? Fuel return to a small header tank sized to keep fuel temperatures low? I think Ed Anderson may have used a small header in his RV6.

Asking for a friend with an airplane addiction.

Bobby

-----Original Message-----
From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net]
Sent: January-20-20 6:01 AM
To: Rotary motors in aircraft
Subject: flyrotary Digest #4865

        Rotary motors in aircraft Digest #4865

1) Re: Mufflers
2) Re: Mufflers

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