REFLECTOR: turning the exhaust exit
Brian Michalk
michalk at awpi.com
Mon Nov 26 10:28:55 CST 2012
I have a six into one on my Franklin that exists aft of the fixed gear.
It should be in the turbulence already. I don't know how I would
measure the benefits, other than oil testing, but it should be turbulent
anyway from the gear.
I also have armpit scoops, but they are variable intake sized, and
faired, so that's another thing.
On 11/26/2012 09:21 AM, Grover McNair wrote:
>
> This is impressive! It still seems to me that a collector for each
> pair would be more efficient. What is the reason for not having a 4
> into 2 setup?
>
> I would like to see how others with six or eight cylinder engines have
> designed their exhaust systems to reduce drag. Has anyone done this
> for a Franklin?
>
> Grover McNair
>
> ------------------------------------------------------------------------
>
> *From:*reflector-bounces at tvbf.org [mailto:reflector-bounces at tvbf.org]
> *On Behalf Of *Douglas Holub
> *Sent:* Sunday, November 25, 2012 6:23 PM
> *To:* Velocity Aircraft Owners and Builders list
> *Subject:* Re: REFLECTOR: turning the exhaust exit
>
> The straight pipes. They are ceramic coated, and I put some aluminum
> tape on the cowl near the pipes as a heat shield. The cowl doesn't get
> hot, and when the propeller is installed at the correct clock with
> respect to TDC, I get very little soot on the propeller.
>
> Doug Holub
>
> ----- Original Message -----
>
> *From:*Mark Magee <mailto:edjonesbrady at gmail.com>
>
> *To:*Velocity Aircraft Owners and Builders list
> <mailto:reflector at tvbf.org>
>
> *Cc:*Velocity Aircraft Owners and Builders list
> <mailto:reflector at tvbf.org>
>
> *Sent:*Friday, November 23, 2012 11:56 AM
>
> *Subject:*Re: REFLECTOR: turning the exhaust exit
>
> All,
>
> I still don't understand why the exhaust isn't shot out the rear
> cooling air exit holes as done on a Long EZ. The newer Long EZ's
> have the tips slightly inboard of the cowl exit for scavenging: no
> issue with drag and possibly better ground cooling. Ceramic
> internal coating of the exhaust greatly reduces the radiated heat
> from the pipes. As well heat shields can easily and inexpensively
> be installed. If the exit holes were opened up, I would think this
> setup would be ideal.
>
> Any configured as such?
>
> Mark B. Magee
>
> Sent from IPhone 4S
>
>
> On Nov 23, 2012, at 10:04 AM, Scott Derrick <scott at tnstaafl.net
> <mailto:scott at tnstaafl.net>> wrote:
>
>> I ended up painting that lower cowl 3 times! ;-)
>>
>> I used Custom Aircraft Parts in San Diego for the exhaust. He
>> sent me the 90's, I cut, fit and marked the pieces, sent them to
>> him for welding, and had them back in 3 days. I had him put in a
>> 1/2 nipple on one side for the air breather tube at the same
>> time. No more oily streak after a long flight!
>>
>> Scott
>>
>> -------- Original Message --------
>> Subject: Re: REFLECTOR: turning the exhaust exit
>> From: Velocity <velocityxl at fastmail.fm>
>> <mailto:velocityxl at fastmail.fm>
>> To: Velocity Aircraft Owners and Builders list
>> <reflector at tvbf.org> <mailto:reflector at tvbf.org>
>> Date: 11/23/2012 08:21 AM
>>
>>> Thanks for the picture I like what you have done. I will try it
>>> also . One reason I keep telling my self
>>> why I have not painted my plane yet still experimenting!
>>>
>>> Ron
>>>
>>> On 11/23/2012 9:11 AM, Scott Derrick wrote:
>>>
>>>> It does work,
>>>>
>>>> I think I increased my top end by 3-5 knots by adding the 90's
>>>> to my exhaust. I have 3-into-1's, one on each side. See
>>>> attached photo.
>>>>
>>>> The ramps in front of the exhaust exit on the cowl were to
>>>> prevent air from entering the lower cowling through the two
>>>> holes(port & starboard) and thus reduce my cooling by raising
>>>> the ambient lower cowl pressure, they also worked well.
>>>>
>>>> I don;t think you loose 10 knots by straight down exhaust, but
>>>> you do loose something.
>>>>
>>>> Scott
>>>>
>>>> -------- Original Message --------
>>>> Subject: Re: REFLECTOR: Reflector Digest, Vol 92, Issue 64
>>>> From: Brian Michalk <michalk at awpi.com> <mailto:michalk at awpi.com>
>>>> To: Velocity Aircraft Owners and Builders list
>>>> <reflector at tvbf.org> <mailto:reflector at tvbf.org>
>>>> Date: 11/23/2012 07:27 AM
>>>>
>>>>> I've heard the 90 degree exhaust so many times, but I can't
>>>>> help think that its an old wives tale. Does anyone have any
>>>>> research that describes the phenomena?
>>>>>
>>>>> Logically, it doesn't make any sense to me that it should be a
>>>>> problem with drag.
>>>>>
>>>>> On 11/22/2012 09:40 AM, Dave T Nelson wrote:
>>>>>
>>>>>> Hi Richard. Your friend is exactly right - you do need to
>>>>>> have slip joints of some type on each cylinder of your
>>>>>> exhaust. You should also check to make sure that they are
>>>>>> free to move - I do that as a part of my preflight. If you
>>>>>> don't, any exhaust will eventually fail, and it can go
>>>>>> through the prop. That's not true of just "in the cowl"
>>>>>> exhaust systems - that's true of _every_ exhaust system. A
>>>>>> safety of some type is also a requirement of any exhaust on a
>>>>>> pusher. Remember - you have to consider _anything_ aft of
>>>>>> the firewall as a direct threat to your prop and make sure
>>>>>> it's safetied...
>>>>>>
>>>>>> I had the two into one exhaust exiting the bottom of the cowl
>>>>>> for awhile. The drag penalty was 8-10 knots. Shooting the
>>>>>> exhaust straight out of the bottom creates a huge plume of
>>>>>> flat plate drag....
>>>>>>
>>>>>> Happy Thanksgiving!
>>>>>>
>>>>>> Dave
>>>>>>
>>>>>> Dave T. Nelson
>>>>>> T/L 553-4327, Voice 507-253-4327, Fax 507-253-3648
>>>>>> Program Director, ISC ECAT NPI & Test Engineering
>>>>>>
>>>>>>
>>>>>>
>>>>>> 1. Re: STG-RG Performance (Richard J. Gentil)
>>>>>>
>>>>>>
>>>>>> ----- Message from "Richard J. Gentil"
>>>>>> <richard at naples-air-center.com>
>>>>>> <mailto:richard at naples-air-center.com> on Thu, 22 Nov 2012
>>>>>> 08:00:21 -0500 -----
>>>>>>
>>>>>> *To:*
>>>>>>
>>>>>>
>>>>>>
>>>>>> Velocity Aircraft Owners and Builders list
>>>>>> <reflector at tvbf.org> <mailto:reflector at tvbf.org>
>>>>>>
>>>>>> *Subject:*
>>>>>>
>>>>>>
>>>>>>
>>>>>> Re: REFLECTOR: STG-RG Performance
>>>>>>
>>>>>> I had the help and advise of a long time builder who had
>>>>>> built several EZ's among his long list of aircraft.
>>>>>>
>>>>>> I was thinking of a EZ style exhaust for my SERG but he
>>>>>> recommended against it because of complexity.
>>>>>>
>>>>>> His primary concern was that you need springs, brackets,
>>>>>> hardware, etc to hold the exhaust in place and many an EZ
>>>>>> owner have had those part break off and go right through the
>>>>>> prop.
>>>>>>
>>>>>> For that reason I went with 2 to 1 exhausts that I cut flush
>>>>>> with the bottom of my cowling safety wired to the engine mount.
>>>>>>
>>>>>> With as fragile as MT props are I wanted to eliminate as best
>>>>>> as possible anything going through the prop.
>>>>>>
>>>>>> Richard
>>>>>>
>>>>>> Sent from my iPhone 5
>>>>>>
>>>>>> On Nov 21, 2012, at 9:31 AM, Dave T Nelson
>>>>>> <dtnelson at us.ibm.com <mailto:dtnelson at us.ibm.com>> wrote:
>>>>>>
>>>>>>
>>>>>> Hi Grover,
>>>>>>
>>>>>> Yes, you absolutely need to be concerned with your prop -
>>>>>> anything and everything that can affect your prop you should
>>>>>> be concerned about! In this case, I am a follower, not a
>>>>>> leader. I'm still very connected with the EZ crowd (I built
>>>>>> a Varieze first and flew it for many years). The EZ guys
>>>>>> were the first to try this kind of exhaust. Prop heating is
>>>>>> for sure the biggest concern.
>>>>>>
>>>>>> For the first hundred hours I flew this exhaust I very
>>>>>> carefully monitored it for any signs of degridation. There
>>>>>> are specific things you look for (surface cracks, a
>>>>>> distinctive "burnt orange" smell, etc.). I have had no
>>>>>> issues (200 - 300 hours on it now).
>>>>>>
>>>>>> I'm certainly not recommending this to anyone - I'm merely
>>>>>> showing what I've done and sharing results. Your results may
>>>>>> vary.
>>>>>>
>>>>>> After many years and hours of use now, the biggest problem I
>>>>>> have with this setup is that a three blade prop can't be
>>>>>> clocked to avoid the exhaust pulse, and so I get soot on the
>>>>>> blades. I've found that "goof off" is the best at removing
>>>>>> the soot.
>>>>>>
>>>>>> I haven't observed any paint coming off the prop at all.
>>>>>> Yes, it's an MT (MTV - 18B (if memory serves)). I'd have to
>>>>>> check, but I believe there's maybe 8 - 10 inches or so from
>>>>>> the exhaust exit to the prop blade.
>>>>>>
>>>>>> Good luck - let me know if you have questions.
>>>>>>
>>>>>> Dave
>>>>>>
>>>>>> Dave T. Nelson
>>>>>> T/L 553-4327, Voice 507-253-4327, Fax 507-253-3648
>>>>>> Program Director, ISC ECAT NPI & Test Engineering
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>> _______________________________________________
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>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>> _______________________________________________
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>>>>>
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>>>>
>>>>
>>>>
>>>> --
>>>> There is no fear in love; but perfect love casteth out fear.
>>>> Bible, 1 John iv. 18.
>>>>
>>>>
>>>>
>>>>
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>>>
>>>
>>>
>>>
>>>
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>>
>>
>>
>> --
>> Let him who is without sin cast the first stone.
>> Jesus Christ
>>
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>
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>
>
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