X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from outbound-mail02.dca.untd.com ([64.136.47.36] verified) by logan.com (CommuniGate Pro SMTP 6.0c1) with SMTP id 5728498 for flyrotary@lancaironline.net; Sat, 25 Aug 2012 08:55:41 -0400 Received-SPF: pass receiver=logan.com; client-ip=64.136.47.36; envelope-from=alwick@juno.com DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=juno.com; s=alpha; t=1345899304; bh=47DEQpj8HBSa+/TImW+5JCeuQeRkm5NMpJWZG3hSuFU=; l=0; h=Message-ID:From:To:Subject:Date:Content-Type; b=X23EUv6LlipixzBOiAuRpgYhQN4tBpMTDJc4auLCV3KG0OTt7rAzFFtW9he+/ok8t klqdnrt+wvLUNWDn8qkGEkZtsIjRPMaiaJ6apY2rcrePl/BydsEcCFNAYVo5n9NPDT NqUhfOU3ZAEtd5o5Li6IyBZ1/h87JKg2gXhJikXA= Received: from Penny (50-39-172-134.bvtn.or.frontiernet.net [50.39.172.134]) by smtpout01.dca.untd.com with SMTP id AABJDTUZVA4TTYNJ for (sender ); Sat, 25 Aug 2012 05:54:11 -0700 (PDT) Message-ID: From: "Al Wick" To: "Rotary motors in aircraft" References: In-Reply-To: Subject: Re: [FlyRotary] Re: fuel pump replaced Date: Sat, 25 Aug 2012 05:54:11 -0700 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_031C_01CD8286.0CD2E9F0" X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Windows Mail 6.0.6002.18197 X-MimeOLE: Produced By Microsoft MimeOLE V6.0.6002.18463 X-UNTD-BodySize: 11987 X-ContentStamp: 28:14:574564614 X-MAIL-INFO:49333fdafa6b5f0b17ea2bb7c7e7d3afc36b576eea8e57b37a7a5ed727277a0f1b6e472be72b2fbefebf2b9b5fea1b021f3f3b2e5a035abbc7ba4e874b3e9b07777733377e3f6b13ef97 X-UNTD-OriginStamp: L941HVjjYzDhN3itp//mkACktNxDsfT5L/qypI9SMAK3EtNteHIEqw== X-UNTD-Peer-Info: 10.171.42.31|smtpout01.dca.untd.com|smtpout01.dca.untd.com|alwick@juno.com This is a multi-part message in MIME format. ------=_NextPart_000_031C_01CD8286.0CD2E9F0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Chad says:
Chad says:
 
<The Cozy is designed ....gives you a small reserve against fuel = sloshing forward during descents.
 
Hi Chad. There are strong indications that the recent Cozy fatality = was=20 caused by poor fuel design. Combination of low fuel and unporting of = fuel during=20 long decent. Further aggravated by his not having a low fuel warning=20 sys. Unporting essentially can't occur with the sump tank approach = I use.=20 Since I have 3 gallon header with all return fuel going to that header. =
 
<fuel is isolated between each tank..........I can isolate a = tank when=20 filling
 
I too have a certain amount of tank isolation, but not all that = great. In=20 my opinion, fuel design is the most difficult thing to accomplish on our = planes.=20 Full of design interactions: Where you focus on one problem, come up = with great=20 solution for that, only to discover you've greatly increased risk of a = different=20 problem. For example, a guy wants to be very thorough in filtering fuel. = "Aha,=20 I'll put in one of these super fine filters". Unaware he's just = increased=20 pressure drop at pump inlet. Greatly increasing vapor lock risk.
 
-al wick
 
 
----- Original Message -----
From:=20 Chad Robinson
Sent: Thursday, August 16, 2012 = 9:41=20 AM
Subject: [FlyRotary] Re: fuel = pump=20 replaced

I guess it depends what you're flying. = The Cozy is=20 designed such that each tank has a small armpit sump because this = guarantees=20 that you always have a low-point drain, and gives you a small reserve = against=20 fuel sloshing forward during descents. I'm not sure what other levels = you'd=20 draw from here because the drain is already at the bottom.

Al = may=20 correct me if I'm wrong, but based on his past posts I believe he's = based his=20 sump strategy on using "wet" pumps, which are designed to be cooled by = immersion in fuel. This is a fine plan and the automakers use it with = high=20 reliability. I wouldn't use a "wet" pump dry - it would never last. = But there=20 are definitely pumps (which I think you have, Tracy sells, and are = available=20 in lots of places as "inline" pumps) designed to run dry and their = reliability=20 is also very good. Any pump can clog, and we're not talking about your = pump=20 overheating here.

I chose a dual-pump, dual-tank configuration = (with a=20 return solenoid) for two reasons:

1. My fuel is isolated = between each=20 tank. Contamination in one doesn't necessarily contaminate the other.=20

2. I have cross-feed capability controlled by a switch under a = safety=20 cover. I can isolate a tank when filling (possibly transfer remaining = fuel=20 from tank A to tank B) and fill only tank B.  I can then take off = on tank=20 A, which is known-good gas, known-good pump, no contamination, no = clogs, no=20 water. (I just flew on it...) If fueling contaminates tank B, loosens = debris,=20 clogs a pump, etc.,  I can be at altitude and prepared to deal = with it=20 when I switch over. (Leave your hand on the switch when switching for = 10=20 seconds or so. Any hiccups, switch back immediately.)

Al would = probably=20 caution us to design against statistics and testing data, rather than=20 designing against fear. It's probably good advice. But I fear bad-fuel = situations and wanted something to help deal with it. YMMV.

On=20 8/16/2012 12:04 PM, Chris Barber wrote:

I am using two fuel pumps.  The Aux was always = quieter.  Now=20 they sound about the same.  I guess since, IIRC, the primary = was always=20 louder I "assumed" it was normal and was just limited to the = individual=20 pump.

 

I was just reviewing Al Wick's sight. He hates the rotary (ok, = that may=20 be too strong, but he is not a fan).  He is using a = Subaru.  I was=20 looking at his sump tank.  He is using in the tank pumps, which = I do=20 not wish to do as of right now.  However, something he did = which I=20 did kinda like was that he had his pumps drawing from different = levels=20 in the tank, like my motorcycle does for it reserve.  That way, = if the=20 primary pumps runs dry, you can switch to the second pump and have a = bit=20 more fuel....hopefully at least enough to pull your head out and get = on the=20 ground.  This seems pretty easy, especially with inline = pumps, to=20 do and like a good idea. Seems as if you would just have to = have one=20 pump out location higher than the other and you have a bit of a=20 reserve.  Yeah, you should be paying attention to = fuel management=20 but this seems like some cheap back up. However, I = could be=20 missing something as currently I am feeding both pumps from the = same=20 outlet. = Thoughts?



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