REFLECTOR: Jeffco or not? (Alcohol problem)

Tue Jan 29 11:17:11 CST 2008

I built my strakes before Jeffco became the fashion.  They were sealed with four coats of EZpoxy and don't leak.  I'm sure that Jeffco is the way to go but I wished to reassure those of you that have non Jeffco tanks that alcohol is probably not going to be a problem.  When Jeffco was recommended as a tank sealer, I ran an experiment to see what alcohol would do to EZpoxy.  I used some scrap lay-up and an olive jar half full of denatured alcohol (mixture of ethanol, methanol and acetone).  I cut the scrap in half and put one piece in the jar and kept the other as a control.  The sample in the jar was half submerged with the upper half exposed to vapor.  The jar was capped and left undisturbed for 60 days.  The alcohol was still clear and free of coloration.  When the sample was removed I could find no difference between it and the control.  There was no sign of gumminess or softening.  I flexed both samples till fracture and found no loss of strength.  Long term exposure (years) could produce different results.

Larry Coen
N136LC

P.S.: Mogas has ethanol added, not methanol.
  ----- Original Message ----- 
  From: Alex Balic 
  To: 'Velocity Aircraft Owners and Builders list' 
  Sent: Monday, January 28, 2008 5:56 PM
  Subject: Re: REFLECTOR: Jeffco or not?

  1)       I would recommend the Jeffco for a couple of reasons- first - it is specifically designed to be a fuel sealer and is more resistant to alcohol content than the epoxy (future concerns?)  also-  the opaque grey color makes it a very simple matter to locate any pin holes (they appear black against the light grey epoxy) while you are constructing. You will not want to try to fine them after your tanks are sealed.  Since I have an auto conversion, I built the entire tank using jeffco since I will almost certainly be burning fuel containing methanol at some point.

  2)       I tested my tanks using a cheap kid's party balloon- you just install the inflated balloon to the vent of the tank you are testing, and see if it is still inflated a day later. It also keeps some positive pressure on the tank if you need to do a soap bubble leak test.

  3)       I would not try to install any of the strake skins without the wings attached- learned this from personal experience- as well as the experience of a couple of other builders- don't use the factory alignment templates either- just hang the wings and keep them there until the strakes are done unless you are ready to apply a lot of filler to make the leading edge of the strake match the leading edge of the wing.

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  From: reflector-bounces at tvbf.org [mailto:reflector-bounces at tvbf.org] On Behalf Of Grigore Rosu
  Sent: Monday, January 28, 2008 12:34 AM
  To: Velocity Aircraft Owners and Builders list
  Subject: REFLECTOR: Jeffco or not?

  I'm about to install the bulkheads in my first strake and therefore I'll soon need to worry about the fuel tank.

  1) Should I use Jeffco or not?  The manual sounds as if Jeffco is optional ...  If I should use it, where can I get it from?  (I can do a random search on the internet, but perhaps there are some better avenues that you may have encountered so far).

  2) Do I need an altimeter to test the fuel tank?  I have none, but the messages I could find in the reflector archive on this subject mention an altimeter.  BTW, can I test each tank in isolation, or they need to be both installed first and checked together?

  3) Should I finish the first strake (including installing the upper strake) and then move to the other one, or it is better to also install the lower strake on the other side and its bulkheads, then do both tanks at the same time, and then install both upper strakes at the same time?  Note that I can only install one wing at a time in my garage.  The flow-chart that came with my manual says that the wing can be removed once the lower strake is installed ... I'm a bit reluctant to do so though, because I'm affraid the torsion generated by the spar may be too big without the upper strake.

  Thank you,

  Grigore

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