REFLECTOR: interference drag

[Brainard, Jerry]

It was my understanding that this was just cosmetic and not expected to
have any structural capability.  As see it, it is a completed strake
with shaped pour foam with some bid over it.  I guess the pour foam
could break down over time, leaving a void that could be moisture
collector.  Don't know if that's a real problem or not.  
 
I have been looking to doing something like this, but have struggled
with how to make it all work with the cowling.  How will this fairing be
carried through to the rear of the engine cover?
 
- jerry
 


________________________________

From: reflector-bounces at tvbf.org [mailto:reflector-bounces at tvbf.org] On
Behalf Of Ken C. Baker
Sent: Tuesday, November 20, 2007 3:25 PM
To: 'Velocity Aircraft Owners and Builders list'
Subject: Re: REFLECTOR: interference drag


Doug,
 
Looks good! A word of caution though - most of the pour foams available
on the market, even the very good ones, do not make good structural
cores. They have very low pcf ratings, and during crystallization they
form irregular cell structures. As well, they are prone to soft spots.
They're great for shaping things that you will ultimately glass over -
but it's important to remove the pour foam, and replace it with a
structural core like 3/8" divinycell, then glass the other side. In
other words, it's important to get that sandwich structure back in there
- especially at a critical structural union like the strake/fuselage
junction.
 
Happy Building,
 
-Ken Baker
kenb at velocityaircraft.com
XL-RG Hybrid-5 in Progress

________________________________

From: reflector-bounces at tvbf.org [mailto:reflector-bounces at tvbf.org] On
Behalf Of Douglas Holub
Sent: Tuesday, November 20, 2007 12:00 PM
To: reflector at tvbf.org
Subject: REFLECTOR: interference drag


I used pour foam to fill in the intersection between the strake and the
fuselage, then shaped it with some 40 grit sand paper glued around a
Clorox bottle. Here's what the fillet looks like with a Clorox bottle
radius. By doing the top and bottom of the wings, strakes, and winglet
intersections this way, I'm hoping to pick up a few extra mph.
 
Doug Holub


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