REFLECTOR: Early model Velocity RG Engine Cooling (Now - which performance mods)?

[stedmanlou at roadrunner.com]

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
> 
> 
> 
> ----- Message from "Richard J. Gentil" <richard at naples-air-center.com> on
> Tue, 20 Nov 2012 10:38:47 -0500 -----
> 
>       To: Velocity Aircraft Owners and Builders list
>           <reflector at tvbf.org>
> 
>  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