REFLECTOR: STG-RG Performance
Douglas Holub
douglas.holub at gmail.com
Fri Nov 23 09:18:55 CST 2012
Where to I clock my 2-blade prop to avoid the exhaust pulses? I think
it was 1 o'clock and 7 o'clock, but I removed my propeller and didn't
mark it before I did and I don't remember now.
Doug Holub
On 11/22/12, Richard J. Gentil <richard at naples-air-center.com> wrote:
> 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> 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
>>
>>
>>
>> <ecblank.gif>
>> From:
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>> reflector at tvbf.org
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>> Date:
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>> 11/21/2012 08:11 AM
>> <ecblank.gif>
>> Subject:
>> <ecblank.gif>
>> Reflector Digest, Vol 92, Issue 55
>> <ecblank.gif>
>> Sent by:
>> <ecblank.gif>
>> reflector-bounces at tvbf.org
>>
>>
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>> 1. Re: STD-RG Performance (Grover McNair)
>>
>> ----- Message from "Grover McNair" <grover at mcnairperformance.com> on Wed,
>> 21 Nov 2012 09:09:04 -0500 -----
>> To:
>> "'Velocity Aircraft Owners and Builders list'" <reflector at tvbf.org>
>> Subject:
>> Re: REFLECTOR: STD-RG Performance
>> Dave,
>> This is interesting. It brings up a few questions. What is the distance
>> from the exhaust tips to the prop? It looks like there may be some paint
>> that has come off because of the exhaust blowing directly on the prop.
>> Have there been any issues because of this? Do you know how hot the prop
>> is getting? Is this an MT constant speed prop? I like the idea but am
>> concerned about the longevity of the prop.
>> Grover McNair
>> 173LW
>> N832AB
>>
>> From: reflector-bounces at tvbf.org [mailto:reflector-bounces at tvbf.org] On
>> Behalf Of Dave T Nelson
>> Sent: Tuesday, November 20, 2012 6:07 PM
>> To: reflector at tvbf.org
>> Subject: REFLECTOR: STD-RG Performance
>>
>> Not sure if this will make it through the reflector or not, but here's a
>> shot of my exhaust....
>>
>> (See attached file: IMG_1045.jpg)
>>
>> Dave
>>
>> Dave T. Nelson
>> T/L 553-4327, Voice 507-253-4327, Fax 507-253-3648
>> Program Director, ISC ECAT NPI & Test Engineering
>>
>>
>> ----- Message from <jerry at jlbent.com> on Tue, 20 Nov 2012 16:22:57 -0500
>> -----
>> To:
>> Velocity Aircraft Owners and Builders list <reflector at tvbf.org>
>> Subject:
>> Re: REFLECTOR: Early model Velocity RG Engine Cooling (Now - which
>> performance mods)?
>> Hey Dave,
>>
>> I would be interested in description of your exhaust. Better still a
>> picture. I don't quite understand how it exist aft of the prop.
>>
>>
>> Jerry Brainard
>> Jerry at JLBEnt.com
>> <ecblank.gif>
>> -------Original Message-------
>> From: Dave T Nelson
>> To: reflector at tvbf.org
>> Subject: Re: REFLECTOR: Early model Velocity RG Engine Cooling (Now -
>> which performance mods)?
>> Sent: Nov 20 '12 3:05pm
>> I've got a STD-RG, Lycoming IO-360 and an MT prop. I started off with
>> armpit scoops feeding into a tops-down plenum, along with a single nose
>> mounted oil cooler. Intake air was off a second scoop mounted on the
>> right wing.
>>
>> My situation was that I built my plane while sharing my shop with a good
>> buddy who built a really nice Cozy 3 place. We got them both flying at
>> about the same time, and spent many happy years racing (and bragging). I
>> still say his plane was the slow ugly one.
>>
>> Anyway, the main thing(s) you do to make these airplanes go fast are all
>> about weight and aerodynamics. Power increases don't get the same bang
>> for the buck. I focused mostly on drag reduction... really clean gear
>> doors, clean canard/fuselage interface, minimum cooling drag, and clean
>> exhaust system. The last two are the most important.
>>
>> The armpit scoops are a bit of an aerodynamic disaster... they are all too
>> big. If you tuft or do an oil study on them, you'll find that the bulk of
>> the air is getting pushed back out of the scoop because of the inherent
>> flow resistance of the tubes taking the air to the top of the plenum, the
>> flow through the plenum & engine, and the output behind the prop. An oil
>> study will likely also show nearly dead air at the output (right behind
>> the prop). The total square inches of inlet are too great, and so is the
>> total square inches of outlet.
>>
>> Many of my initial mods were in trying to clean up the cooling and intake
>> air.. I made several different styles of cooling air intakes, each
>> smaller than the last. Nothing worked particularly well. Eventually,
>> after developing significant cooling issues (which turned out to be an
>> engine issue, not an aer! odynamic problem), I went to the rooftop NACAs.
>> As I said... they work fabulously. I take my induction air off the right
>> NACA. There are no external protrusions on my plane.
>>
>> The exhaust changes were probably the most speed gain. I've gone from the
>> original rear exiting 2 in 1's that exit through tubes attached to the
>> lower cowl, to the "straight out the bottom" types you see on many XLs
>> today (which were by far the worst performers - a real disaster), to what
>> I have today - a one-of design of my own that keeps the entire exhaust
>> inside the cowl and exits aft of the prop. That was a big gain!
>>
>> OK, performance... I see around 185 knots true +/- at around 25 squared...
>> middling altitudes... at around 10 - 11 gallons / hour ... cold air, down
>> low, with a light plane is better still. It's not as fast as I'd like,
>> but I'm not done trying. The next ! effort will be a complete cowl
>> redesign to get rid of those awful turns! where the cowl angles in just
>> aft of the last cylinder. All the attached air detaches at that point...
>>
>> Hope this helps. What numbers to you see?
>>
>> Dave
>>
>> Dave T. Nelson
>> T/L 553-4327, Voice 507-253-4327, Fax 507-253-3648
>> Program Director, ISC ECAT NPI & Test Engineering
>>
>>
>> ----- Message from "Richard J. Gentil" on Tue, 20 Nov 2012 10:38:47 -0500
>> -----
>>
>> To:
>> Velocity Aircraft Owners and Builders list
>> Subject:
>> Re: REFLECTOR: Early model Velocity RG Engine Cooling (David Smith)
>>
>> Dave N,
>>
>> Which go fast mod have you done and what speeds are you getting? (Please
>> mention the engine and prop combo you are running.)
>>
>> Thanks,
>>
>> Richard
>>
>> Sent from my iPhone 5
>>
>> _______________________________________________
>> To change your email address, visit
>> http://www.tvbf.org/mailman/listinfo/reflector
>>
>> Visit the gallery! www.tvbf.org/gallery
>> user:pw = tvbf:jamaicangoose
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>>
>> ----- Message from Scott Baker <scottb33333 at gmail.com> on Tue, 20 Nov 2012
>> 16:30:39 -0500 -----
>> To:
>> geoff.gerhardt at gmail.com, Velocity Aircraft Owners and Builders list
>> <reflector at tvbf.org>
>> Subject:
>> Re: REFLECTOR: Need some advice/measurements
>> Awesome video !!
>> Scott B.
>>
>> On 11/20/2012 2:51 PM, Geoff Gerhardt wrote:
>> > I had to move my SE-RG in and out of my shop (single-car garage door)
>> > a couple times. Here's how I did it. I wouldn't try this with an
>> > engine on, tho. Its relatively easy to pull an engine off, tho.
>> >
>> > http://thegerhardts.com/velocity/?p=292
>> >
>> > There's a video in that post that shows my wife and I moving it out of
>> > the shop on a cradle.
>> >
>> > Geoff
>> >
>>
>> ----- Message from none <markinchampions at gmail.com> on Tue, 20 Nov 2012
>> 15:58:50 -0600 -----
>> To:
>> "jerry at jlbent.com" <jerry at jlbent.com>, Velocity Aircraft Owners and
>> Builders list <reflector at tvbf.org>
>> Subject:
>> Re: REFLECTOR: Early model Velocity RG Engine Cooling (Now - which
>> performance mods)?
>> Me too.
>>
>> On Nov 20, 2012, at 3:22 PM, <jerry at jlbent.com> wrote:
>> Hey Dave,
>>
>> I would be interested in description of your exhaust. Better still a
>> picture. I don't quite understand how it exist aft of the prop.
>>
>>
>> Jerry Brainard
>> Jerry at JLBEnt.com
>> <ecblank.gif>
>> -------Original Message-------
>> From: Dave T Nelson
>> To: reflector at tvbf.org
>> Subject: Re: REFLECTOR: Early model Velocity RG Engine Cooling (Now -
>> which performance mods)?
>> Sent: Nov 20 '12 3:05pm
>> I've got a STD-RG, Lycoming IO-360 and an MT prop. I started off with
>> armpit scoops feeding into a tops-down plenum, along with a single nose
>> mounted oil cooler. Intake air was off a second scoop mounted on the
>> right wing.
>>
>> My situation was that I built my plane while sharing my shop with a good
>> buddy who built a really nice Cozy 3 place. We got them both flying at
>> about the same time, and spent many happy years racing (and bragging). I
>> still say his plane was the slow ugly one.
>>
>> Anyway, the main thing(s) you do to make these airplanes go fast are all
>> about weight and aerodynamics. Power increases don't get the same bang
>> for the buck. I focused mostly on drag reduction... really clean gear
>> doors, clean canard/fuselage interface, minimum cooling drag, and clean
>> exhaust system. The last two are the most important.
>>
>> The armpit scoops are a bit of an aerodynamic disaster... they are all too
>> big. If you tuft or do an oil study on them, you'll find that the bulk of
>> the air is getting pushed back out of the scoop because of the inherent
>> flow resistance of the tubes taking the air to the top of the plenum, the
>> flow through the plenum & engine, and the output behind the prop. An oil
>> study will likely also show nearly dead air at the output (right behind
>> the prop). The total square inches of inlet are too great, and so is the
>> total square inches of outlet.
>>
>> Many of my initial mods were in trying to clean up the cooling and intake
>> air.. I made several different styles of cooling air intakes, each
>> smaller than the last. Nothing worked particularly well. Eventually,
>> after developing significant cooling issues (which turned out to be an
>> engine issue, not an aer! odynamic problem), I went to the rooftop NACAs.
>> As I said... they work fabulously. I take my induction air off the right
>> NACA. There are no external protrusions on my plane.
>>
>> The exhaust changes were probably the most speed gain. I've gone from the
>> original rear exiting 2 in 1's that exit through tubes attached to the
>> lower cowl, to the "straight out the bottom" types you see on many XLs
>> today (which were by far the worst performers - a real disaster), to what
>> I have today - a one-of design of my own that keeps the entire exhaust
>> inside the cowl and exits aft of the prop. That was a big gain!
>>
>> OK, performance... I see around 185 knots true +/- at around 25 squared...
>> middling altitudes... at around 10 - 11 gallons / hour ... cold air, down
>> low, with a light plane is better still. It's not as fast as I'd like,
>> but I'm not done trying. The next effort will be a complete cowl redesign
>> to get rid of those awful turns! where the cowl angles in just aft of the
>> last cylinder. All the attached air detaches at that point...
>>
>> Hope this helps. What numbers to you see?
>>
>> Dave
>>
>> Dave T. Nelson
>> T/L 553-4327, Voice 507-253-4327, Fax 507-253-3648
>> Program Director, ISC ECAT NPI & Test Engineering
>>
>>
>>
>> ----- Message from "Richard J. Gentil" on Tue, 20 Nov 2012 10:38:47 -0500
>> -----
>>
>> To:
>> Velocity Aircraft Owners and Builders list
>> Subject:
>> Re: REFLECTOR: Early model Velocity RG Engine Cooling (David Smith)
>>
>> Dave N,
>>
>> Which go fast mod have you done and what speeds are you getting? (Please
>> mention the engine and prop combo you are running.)
>>
>> Thanks,
>>
>> Richard
>>
>> Sent from my iPhone 5
>>
>> _______________________________________________
>> To change your email address, visit
>> http://www.tvbf.org/mailman/listinfo/reflector
>>
>> Visit the gallery! www.tvbf.org/gallery
>> user:pw = tvbf:jamaicangoose
>> Check new archives: www.tvbf.org/pipermail
>> Check old archives: http://www.tvbf.org/archives/velocity/maillist.html
>> _______________________________________________
>> To change your email address, visit
>> http://www.tvbf.org/mailman/listinfo/reflector
>>
>> Visit the gallery! www.tvbf.org/gallery
>> user:pw = tvbf:jamaicangoose
>> Check new archives: www.tvbf.org/pipermail
>> Check old archives:
>> http://www.tvbf.org/archives/velocity/maillist.html_______________________________________________
>> Visit the gallery! tvbf:jamaicangoose[attachment "image001.gif" deleted
>> by Dave T Nelson/Rochester/IBM]
>> _______________________________________________
>> Visit the gallery! tvbf:jamaicangoose
>>
>> _______________________________________________
>> To change your email address, visit
>> http://www.tvbf.org/mailman/listinfo/reflector
>>
>> Visit the gallery! www.tvbf.org/gallery
>> user:pw = tvbf:jamaicangoose
>> Check new archives: www.tvbf.org/pipermail
>> Check old archives: http://www.tvbf.org/archives/velocity/maillist.html
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