REFLECTOR: interference drag

[Douglas Holub]

Thanks for the heads up. I'm not using it for strength, though, just for a fairing. I glassed the strake to the fuselage normally, then poured the foam and shaped the fillet, then put two plies of BID over the shaped foam fillet.

Doug
  ----- Original Message ----- 
  From: Ken C. Baker 
  To: 'Velocity Aircraft Owners and Builders list' 
  Sent: Tuesday, November 20, 2007 2:25 PM
  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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