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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| Date: |
|------------>
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|11/21/2012 08:11 AM |
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| Subject: |
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|Reflector Digest, Vol 92, Issue 55 |
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Today's Topics:
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
-------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
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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
|------>
| |
|------>
>--------------------------------------------------------------------------------------------------------------------------------------------------|
| -------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 |
| |
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| user:pw = tvbf:jamaicangoose |
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>--------------------------------------------------------------------------------------------------------------------------------------------------|
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Check new archives: www.tvbf.org/pipermail
Check old archives:
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