X-Junk-Score: 0 [] X-Cloudmark-Score: 0 [] X-Cloudmark-Analysis: v=2.2 cv=No+TSIVJ c=1 sm=1 tr=0 a=VFNU8TuZLTvgd6dDXVyjSw==:117 a=IrvoUvzoI6vFScZsnRROXw==:17 a=x7bEGLp0ZPQA:10 a=A-0mRrAPPO4A:10 a=3JhidrIBZZsA:10 a=r77TgQKjGQsHNAKrUKIA:9 a=4LZCcvUXAAAA:8 a=pGLkceISAAAA:8 a=wrnlkVK_AAAA:8 a=Ia-xEzejAAAA:8 a=7g1VtSJxAAAA:8 a=HLElNSDFAAAA:8 a=N4BA22dSAAAA:8 a=_6GpL_ENAAAA:8 a=3pVMzoCApfVH85UjPP8A:9 a=qHwWKUpA7GwHhL1e:21 a=hbF16wpn0NdA4l2Z:21 a=QEXdDO2ut3YA:10 a=jpqcyI-gQgoA:10 a=Qa1je4BO31QA:10 a=izEWSWqvyK8A:10 a=KqsoOQp8tHIA:10 a=ooph3NpzJo8A:10 a=gvSQh4r-fQ0A:10 a=4PR2P7QzAAAA:8 a=GPxPIjEV0wQnMWZuM34A:9 a=lDNl2lIEhZKvKMjIUR5gOGDH5rM=:19 a=JhQgQuuorIc6e4GB:21 a=jdiCoKUDlgO1MVpS:21 a=DyJtfwDK6e5sIclu:21 a=_W_S_7VecoQA:10 a=TRfWRy4FXhQwmuKf2c8o:22 a=ABpvz31vvg_prsUBKvxG:22 a=Urk15JJjZg1Xo0ryW_k8:22 a=grOzbf7U_OpcSX4AJOnl:22 a=NTybjnMHmzLOwcLJc94Q:22 a=DfVtRexSPdyR86Qi2_78:22 a=4dqwQCo7Po2mVW515mGf:22 From: "Charlie England ceengland7@gmail.com" Received: from mail-yw1-f52.google.com ([209.85.161.52] verified) by logan.com (CommuniGate Pro SMTP 6.2.10) with ESMTPS id 12075602 for flyrotary@lancaironline.net; Sun, 06 Jan 2019 17:11:21 -0500 Received-SPF: pass receiver=logan.com; client-ip=209.85.161.52; envelope-from=ceengland7@gmail.com Received: by mail-yw1-f52.google.com with SMTP id d190so16500968ywd.12 for ; Sun, 06 Jan 2019 14:11:22 -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=WW7+hUk4XQgkV9Tr0usdH7FDrY6trMJ7fJTGRVFplb8=; b=tVlBm9HoI11O2IPqGZpJeCbDTFLsdbQgwZcb3UCRfBA5Y+yduE5hOODmartE18dYBE OklvcCQsIzKynmn/3MD/0tQpfuY5E9d2FeUmlXUPM/P+EBtAYIKLot0kSpZlJp41swd6 wVU0LKdqdo7DOJ8hwkbznuJrCvQA53fLUpHv6Bcs6EG7MrNWUae+3ctrzuQGvpfXJOXJ 1e7wCM0lDlpCp+Xs0XN0mrC2TmGmCmx83HsRGWtMIQ4IoJF7+2mkgUrBqKf6nWifZRhu qvIJTuQw+ky+0NTJRvkwjAxtrmrJSlTk2dS5D0K1RZCgONF9YppqZgvFVIOiw6/eloLf uEKw== 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=WW7+hUk4XQgkV9Tr0usdH7FDrY6trMJ7fJTGRVFplb8=; b=KTKJvzIng5uzhadLijTKCVxWFgXJMHQ+CHW1YL9/RFCKnLrv6TjIU3RHBQuKKW0fQK SMOGbGoh0jQcNbyVwkg7nhH/FzOeCoz/VqURn0QW2woMCYOBGSk70pWK3SRjGSLneAn3 NMa9fwDsWYHb/crNJOez1gLhJazAfeD3L9ifDAjH8gOCBC7OhFDw6mgbCWLrZ9gkoDXM nqI1ZbwXCRaMuvEheAEkQgc0ZHJO5r2X4Y/kDD4rEh3+n9G2EGwgR34bOE1Z4/6r2PWA Xtdr1UFyNhFeTOTDKzhHBZi8oYcqBIH3oMW/fljvq20iJMnC4YJ6I/Q3c7rFufTkIN4z jgZw== X-Gm-Message-State: AA+aEWbKUek7JPtq7YSTrEfOL/MILB0L+nQFI8jc9fhUT9U4Llz1nYhC oiy7MwQWnZCc76+LecU7ZkuVkZZA X-Google-Smtp-Source: AFSGD/U2LLfh0tN/CqUD37ckRB1gau1axd+/qHYBGBJlSjuIDiWV5+7tHIX8M3+zOMQEdGuxzmHKag== X-Received: by 2002:a0d:f743:: with SMTP id h64mr60534075ywf.498.1546812663922; Sun, 06 Jan 2019 14:11:03 -0800 (PST) Return-Path: Received: from [192.168.10.217] (mobile-166-177-186-115.mycingular.net. [166.177.186.115]) by smtp.googlemail.com with ESMTPSA id d3sm46121336ywc.103.2019.01.06.14.11.02 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Sun, 06 Jan 2019 14:11:03 -0800 (PST) Subject: Re: [FlyRotary] Re: Exhaust setup's To: Rotary motors in aircraft References: Message-ID: <4c89e62d-e542-fc05-3f97-d39142c65ada@gmail.com> Date: Sun, 6 Jan 2019 16:13:55 -0600 User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:60.0) Gecko/20100101 Thunderbird/60.3.3 MIME-Version: 1.0 In-Reply-To: Content-Type: multipart/alternative; boundary="------------439E58CAE15DD98A111CEEB2" Content-Language: en-US X-Antivirus: Avast (VPS 190106-4, 01/06/2019), Outbound message X-Antivirus-Status: Clean This is a multi-part message in MIME format. --------------439E58CAE15DD98A111CEEB2 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit There's a Lancair guy and a Mustang II guy who both post fairly often on the list. I'm sure you'd survive, as long as the subject can be tied to RVs in some way. Did you compare the outside shape of your 'afterbody' to Vetterman's? His is much more of a convex 'egg' shape.  Have you tried to tuft test yours? I'm thinking about the horizontal equivalent of what's happening in the vertical plane in the video in that 2nd thread. The eductors I've seen seem to have much shorter ducts, and the exhaust energizes the duct by shooting into it, rather than being submerged in it. I just found this site, which looks closer to what I was thinking. http://nickugolini.com/website/Eductor.html The super high velocity exhaust stream is pretty potent in dragging cooling air along with it, without the drag of all those small holes. Another example is what was once the world's fasted RV-6, that had the pipe cut just an inch or so inside the cooling outlet (just forward of the firewall). I talked to the builder at SNF; he described cutting the pipes a half inch at a time, trying to tune for power. when he got to the exit, he decided to 'gamble' on shortening them one more time where they'd exit inside the cowl, and he saw an improvement in oil cooling after the cut. Charlie On 1/6/2019 11:59 AM, Matt Boiteau mattboiteau@gmail.com wrote: > Thanks guys. I browse the RV forum religiously, there is so much good > information on there. I did come across and save a lot of posts from > DanH but not the second one you mentioned Charlie. I don't know how > they feel, if I post stuff on there without being an RV owner? The > subcowl I fiberglassed, is the back half shape of a tear drop. Much > like the Vetterman setup. Should help speed up the inside cowl air to > align to the tip of the tear drop, where an opening will be for the > exhaust pipe. Also will allow the outside air the stay attached to the > bottom and sides of the subcowl. > > The perforated inner tube would face aft. The idea was to  allow the > slowing moving cowl air, to get sucked into the faster moving exhaust > tube. But I think for now, I'll just cut the exhaust pipe short inside > the bigger outer pipe. This will take place inside the subcowl. Then > the bigger outer pipe will exit the tip of the tear drop, all the way > down the belly of the plane. Where the pipe stops changing color from > the exhaust heat, I'll cut off there. That will be my baseline. > > Inside the subcowl, the front of the outer tube (eductor) will have > some type of bellmouth on it. I found a few on the internet, but I may > 3D print one as a mold, then fiberglass overtop. I've done that a few > times now with designing parts. > https://www.summitracing.com/int/parts/vpe-10953/overview/ > > I have a butterfly valve on my oil outlet, which will keep temps where > I want them during slow / fast speeds. Still need to make a big flap > for my coolant outlet though, so it can do the same thing. This will > allow me to really know if my inlets are too big / too small based on > how far the flaps need to close / open to keep temps. > > - Matt Boiteau >> >> On 1/5/2019 10:49:04 PM, Charlie England ceengland7@gmail.com >> wrote: >> >> On 1/5/2019 11:32 AM, Matt Boiteau mattboiteau@gmail.com wrote: >>> *Anybody have advice on how they run their exhaust exit systems?* >>> >>> - Matt Boiteau >>> >>> ------ Forwarded Message -------- >>> From: Matt Boiteau mattboiteau@gmail.com >>> Date: 12/9/2018 10:13:56 PM >>> Subject: [FlyRotary] Exhaust setup's >>> To: Rotary motors in aircraft >>> >>> I'm at the stage of securing an exhaust setup. How do you guys do it? >>> >>> I'll have a sub-cowl under the belly of the plane (shape of a tear >>> drop), which will streamline the main cowl air (coolant and oil >>> outlets). >>> >>> I'm thinking I exit the exhaust (2.5" pipe) inside the sub-cowl and >>> have a 5" wrapped around it which ends out the sub-cowl for x >>> length. This should help create a vacuum and pump out the main cowl air. >>> >>> Before exiting the main exhaust pipe, should I have perforated holes >>> or louvers in it? >>> >>> >>> - Matt Boiteau >>> -- Homepage: http://www.flyrotary.com/ Archive and UnSub: >>> http://mail.lancaironline.net:81/lists/flyrotary/List.html >>> >> Hi Matt, >> >> I'm no engineer, but I do know a few engineers with recent hotel >> time. :-) >> >> Have you read this thread? >> http://www.vansairforce.com/community/showthread.php?t=68241&highlight=cowl >> >> This is a later thread, with postings & references back to the link >> above: >> http://www.vansairforce.com/community/showthread.php?t=159473&highlight=cowl >> Watch Onewinglo's youtube video & try to visualize what the air's >> doing wrong as it comes out of the cowl. >> >> It's about cooling a Lyc, but cooling is cooling. It's a long thread, >> but reading anything posted by DanH is worthy of respect. Note all >> the attention to smoothly curved entry areas, and the ultimate 'bluff >> body' (squared off) exit, with the external surfaces parallel to the >> free stream around the a/c. >> >> I could be wrong, but I see a lot of skin drag with the >> tube-in-a-tube, with the exit air having to scrub on both tubes to >> get out. Also a *lot* of drag where the cooling outlet air enters the >> outer tube (reference: 'bellmouth' & 'velocity stack'). Is the >> perforated inner tube intended to be a muffler? If so, it's kinda >> like  the inner tube of a Spintech muffler, but the dimpled slots >> face aft in the Spintech. The spintech works great as a rotary >> muffler, if that's your goal. >> >> There's lots of NACA & NASA research on eductors, if you do a little >> digging. Most of the stuff I've seen says that they can work great at >> low speeds, at the expense of excess cooling drag in cruise. A good >> storehouse of reading material is the CAFE Foundation. Try here: >> https://cafe.foundation/v2/tech_enablingtech_dragreduction.php >> and here: >> https://cafe.foundation/v2/research_reports.php >> with attention to the three 'Local Flow' articles in the 2nd link. >> >> Here's hoping I'm not making things worse, >> >> Charlie >> >> >> ------------------------------------------------------------------------ >> Avast logo >> >> This email has been checked for viruses by Avast antivirus software. >> www.avast.com >> >> >> <#DAB4FAD8-2DD7-40BB-A1B8-4E2AA1F9FDF2> > > -- > Homepage: http://www.flyrotary.com/ > Archive and UnSub: http://mail.lancaironline.net:81/lists/flyrotary/List.html --------------439E58CAE15DD98A111CEEB2 Content-Type: text/html; charset=utf-8 Content-Transfer-Encoding: 8bit
There's a Lancair guy and a Mustang II guy who both post fairly often on the list. I'm sure you'd survive, as long as the subject can be tied to RVs in some way.

Did you compare the outside shape of your 'afterbody' to Vetterman's? His is much more of a convex 'egg' shape.  Have you tried to tuft test yours? I'm thinking about the horizontal equivalent of what's happening in the vertical plane in the video in that 2nd thread.

The eductors I've seen seem to have much shorter ducts, and the exhaust energizes the duct by shooting into it, rather than being submerged in it. I just found this site, which looks closer to what I was thinking.
http://nickugolini.com/website/Eductor.html
The super high velocity exhaust stream is pretty potent in dragging cooling air along with it, without the drag of all those small holes.
Another example is what was once the world's fasted RV-6, that had the pipe cut just an inch or so inside the cooling outlet (just forward of the firewall). I talked to the builder at SNF; he described cutting the pipes a half inch at a time, trying to tune for power. when he got to the exit, he decided to 'gamble' on shortening them one more time where they'd exit inside the cowl, and he saw an improvement in oil cooling after the cut.

Charlie

On 1/6/2019 11:59 AM, Matt Boiteau mattboiteau@gmail.com wrote:
Thanks guys. I browse the RV forum religiously, there is so much good information on there. I did come across and save a lot of posts from DanH but not the second one you mentioned Charlie. I don't know how they feel, if I post stuff on there without being an RV owner? The subcowl I fiberglassed, is the back half shape of a tear drop. Much like the Vetterman setup. Should help speed up the inside cowl air to align to the tip of the tear drop, where an opening will be for the exhaust pipe. Also will allow the outside air the stay attached to the bottom and sides of the subcowl.

The perforated inner tube would face aft. The idea was to  allow the slowing moving cowl air, to get sucked into the faster moving exhaust tube. But I think for now, I'll just cut the exhaust pipe short inside the bigger outer pipe. This will take place inside the subcowl. Then the bigger outer pipe will exit the tip of the tear drop, all the way down the belly of the plane. Where the pipe stops changing color from the exhaust heat, I'll cut off there. That will be my baseline.

Inside the subcowl, the front of the outer tube (eductor) will have some type of bellmouth on it. I found a few on the internet, but I may 3D print one as a mold, then fiberglass overtop. I've done that a few times now with designing parts.
https://www.summitracing.com/int/parts/vpe-10953/overview/

I have a butterfly valve on my oil outlet, which will keep temps where I want them during slow / fast speeds. Still need to make a big flap for my coolant outlet though, so it can do the same thing. This will allow me to really know if my inlets are too big / too small based on how far the flaps need to close / open to keep temps.

- Matt Boiteau

On 1/5/2019 10:49:04 PM, Charlie England ceengland7@gmail.com <flyrotary@lancaironline.net> wrote:

On 1/5/2019 11:32 AM, Matt Boiteau mattboiteau@gmail.com wrote:
*Anybody have advice on how they run their exhaust exit systems?*

- Matt Boiteau

------ Forwarded Message --------
From: Matt Boiteau mattboiteau@gmail.com <flyrotary@lancaironline.net>
Date: 12/9/2018 10:13:56 PM
Subject: [FlyRotary] Exhaust setup's
To: Rotary motors in aircraft <flyrotary@lancaironline.net>

I'm at the stage of securing an exhaust setup. How do you guys do it?

I'll have a sub-cowl under the belly of the plane (shape of a tear drop), which will streamline the main cowl air (coolant and oil outlets).

I'm thinking I exit the exhaust (2.5" pipe) inside the sub-cowl and have a 5" wrapped around it which ends out the sub-cowl for x length. This should help create a vacuum and pump out the main cowl air.

Before exiting the main exhaust pipe, should I have perforated holes or louvers in it?


- Matt Boiteau
-- Homepage: http://www.flyrotary.com/ Archive and UnSub: http://mail.lancaironline.net:81/lists/flyrotary/List.html

Hi Matt,

I'm no engineer, but I do know a few engineers with recent hotel time. :-)

Have you read this thread?
http://www.vansairforce.com/community/showthread.php?t=68241&highlight=cowl

This is a later thread, with postings & references back to the link above:
http://www.vansairforce.com/community/showthread.php?t=159473&highlight=cowl
Watch Onewinglo's youtube video & try to visualize what the air's doing wrong as it comes out of the cowl.

It's about cooling a Lyc, but cooling is cooling. It's a long thread, but reading anything posted by DanH is worthy of respect. Note all the attention to smoothly curved entry areas, and the ultimate 'bluff body' (squared off) exit, with the external surfaces parallel to the free stream around the a/c.

I could be wrong, but I see a lot of skin drag with the tube-in-a-tube, with the exit air having to scrub on both tubes to get out. Also a *lot* of drag where the cooling outlet air enters the outer tube (reference: 'bellmouth' & 'velocity stack'). Is the perforated inner tube intended to be a muffler? If so, it's kinda like  the inner tube of a Spintech muffler, but the dimpled slots face aft in the Spintech. The spintech works great as a rotary muffler, if that's your goal.

There's lots of NACA & NASA research on eductors, if you do a little digging. Most of the stuff I've seen says that they can work great at low speeds, at the expense of excess cooling drag in cruise. A good storehouse of reading material is the CAFE Foundation. Try here:
https://cafe.foundation/v2/tech_enablingtech_dragreduction.php
and here:
https://cafe.foundation/v2/research_reports.php
with attention to the three 'Local Flow' articles in the 2nd link.

Here's hoping I'm not making things worse,

Charlie


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