REFLECTOR: Reflector Digest, Vol 92, Issue 53

[Dave T Nelson]

Hi Lou

Sure, I've got lots of pictures - what would you like to see?

My engine is a standard Lycoming IO-360.  I use a Klaus Light Speed
ignition on one side.  Other than that there are really no engine mods.

You should be seeing way more than 145 knots... What engine?  What prop?

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 <stedmanlou at roadrunner.com> on Tue, 20 Nov 2012 19:16:09
-0500 -----
                                                                                    
      To: Velocity Aircraft Owners and Builders list <reflector at tvbf.org>           
                                                                                    
      cc: Dave T Nelson <dtnelson at us.ibm.com>                                       
                                                                                    
 Subject: Re: REFLECTOR: Early model Velocity RG Engine Cooling (Now - which        
          performance mods)?                                                        
                                                                                    


Wow I can't believe those numbers. I am lucky to see 145kts. What HP is
your 360? Do you have pictures?
--
Lou Stedman
LEZ N9EC
Olean, NY

---- Dave T Nelson <dtnelson at us.ibm.com> wrote:
>
> 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 aerodynamic 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
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