REFLECTOR: Jeffco or not?
Andy Millin
amillin at sbcglobal.net
Mon Jan 28 15:40:30 CST 2008
Hee hee Grigore,
Flanging the baffles ... is it absolutely necessary?
NOPE! Not close to necessary. It's not even in the manual.
Many builders have successfully made their strakes without flanging the
baffles.
The factory does not flange their baffles. They use the procedure in the
manual and I'll bet they get a prefect seal every time. That being said,
they have done more than one set of strakes. Heck, Scott Swing might have
done over 100 of these. My set might very well be the only set I'll ever
do.
Like most builders (I might be making a bad assumption here), I have done
quite a bit of reading. The reflector and builder sites have been gold
mines. My issue wasn't as much that I wanted the strakes to seal as much as
I REALLY didn't want to have a leak. Ha! (I hope I didn't twist your head
too much there)
There are some on the list that have had to fight the leaky strake demon.
Diagnosis of the problem can be a major task. Pressurize the tanks, cover
with soapy water, lift the wing while under pressure to see if it is
affected by load... Ugh.
The fix can be as simple as a vacuum and some wet epoxy. On the other hand,
Velocity had a case where the bottom skin of the strake AND the foam had to
be removed to fix it. I know this is an extreme case, but it's there.
Again I'm showing my builder age. <blush> I had spoken with Brendan about
the strakes. He said it is our natural inclination to save weight on the
plane; make things light. This is good. However, on the strakes, don't
worry about it. He guaranteed me that I would be so much happier if my
plane was 10 1b. heavier and the strakes were sealed than if I tried to save
the 10 lbs and wound up chasing a leak.
>> I'd prefer to go with the standard approach to save time, hoping that my
tanks will not leak
I didn't want to take the chance. I wanted all the insurance I could get.
The flanges provided more contact area and I liked it. I got a good seal on
my strakes so I'm happy with what I did.
In the end you will have to do what your heart and head tell you.
Andy
-----Original Message-----
From: reflector-bounces at tvbf.org [mailto:reflector-bounces at tvbf.org] On
Behalf Of Grigore Rosu
Sent: 01-28-2008 2:59
To: Velocity Aircraft Owners and Builders list
Subject: Re: REFLECTOR: Jeffco or not?
Hi Andy,
Thank you for your elaborate answer.
Just a clarification regarding your answer:
You said:
"I did flange the tops of the baffles. Very grateful to Joe for sending the
pics and write-up. I too was able to complete the strakes without flipping
the plane. I also was fortunate enough to have the strakes hold pressure
for 24+ hours. Whew..."
I saw your pictures on the web and they are nice. However, if not
absolutely necessary, I'd prefer to go with the standard approach to save
time, hoping that my tanks will not leak. Have these flanges had anything
to do with flipping the airplane over? It seems to me that these are two
ortoghonal issues, but better check.
Is it true than that the main reason for flipping the airplan is to more
easilly install the BID layups between the upper strake and the spar? In
theory, I can see some solutions to that part without flipping the airplane;
as usual, the practice will be the decisive part.
Grigore
On Jan 28, 2008 11:11 AM, Andy Millin <amillin at sbcglobal.net> wrote:
>> BTW, what are the actual reasons for flipping the airplane over?
I believe it makes it easier to do the lay-ups from the top of the
spar to
the top strake skin, and from the aft fuel bulkhead to the top
strake skin.
Also makes it easier to do the finish work between the fuselage and
the
lower strake skin. But, I wouldn't know. I never flipped my plane.
:)
Andy
-----Original Message-----
From: reflector-bounces at tvbf.org [mailto:reflector-bounces at tvbf.org]
On
Behalf Of Grigore Rosu
Sent: 01-28-2008 11:38
To: Velocity Aircraft Owners and Builders list
Subject: Re: REFLECTOR: Jeffco or not?
Thank you, I will then go ahead and order the Jeffco. In the
meanwhile I'll
finish trimming the bulkheads and the buffles (what a job! and I
thought
that trimming to fit the panel was a lot of work ...).
I will soon send a link to my airplane webpage (still have to upload
tons of
pictures); that will show how I keep the airplane level: I'm not
using
bottle jacks, I have some special-made sawhorses that are quite
rigid and do
not let the airplane touch the ground at all. I measure the three
angles
everyday before I start working and nothing changed so far in about
one
month since I suspended it.
BTW, what are the actual reasons for flipping the airplane over? It
sounds
to me like a very difficult and risky job, which I'd like to avoid
by any
means. It would have been so useful to have a special section in
the manual
explaining what to do when the airplane is upside down!
Grigore
On Jan 28, 2008 9:06 AM, Andy Millin <amillin at sbcglobal.net> wrote:
Hey Grigore,
Joe is a pretty savvy builder, and I agree with everything he
wrote.
I too bought my Jeffco from the factory. They now have a
slower
hardener
that will give you better working time. The color difference
from
the EZ-84
provides great contrast. Much easier to tell if you have a
thin
spot.
I did flange the tops of the baffles. Very grateful to Joe
for
sending the
pics and write-up. I too was able to complete the strakes
without
flipping
the plane. I also was fortunate enough to have the strakes
hold
pressure
for 24+ hours. Whew...
As for the lower strake/removing the wing question: I spoke
with
Rob
Johnson some time ago. Many of the "Old Timers" on the list
will
remember
the Ditch Master. Rob did not have room to put both wings on
in his
garage.
His solution was to roll the fuselage out of the garage,
install the
wings,
install the lower strakes, remove the wings, and roll it back
into
the
garage to complete the strakes. He did it all in one
weekend!
Much later when he put the wings on, they were misaligned by
about
1/2" on
each side. His experience said the strakes are not locked-in
until
the
upper skin is bonded on. I listened to his experience, and
did not
remove
the wing until the strake was completed.
I know this method worked. I have had the wings back on a
couple
times
since then and everything still lines up. The other thing
that we
did not
get into was wing incidence. If the strakes were no longer
aligned
with the
wing, then one could reason the incidence of the strake,
wing, or
both was
no longer what was desired. Brendan had written about this
in his
"The Sh*t
that Flies" column. A Velocity can fly with things really
out of
alignment.
Almost by definition, it will mean drag and a slower
airplane. One
of the
best drag reduction favors you can do for yourself is to
build a
true
airframe.
One small tip on the strakes. Most of us use a bottle jack
on some
type of
stand on the outboard wing to hold the incidence during
strake
construction.
Bottle jacks are not meant to hold the same position
indefinitely.
Some
know this lesson in a painful way. They WILL slowly bleed
down. I
used
hose clamps around the ram of the jack to lock it in place.
There
is a
picture somewhere on my site. It worked very well.
I liked Joe's idea of using a balloon. I used a simple water
manometer.
Remember, you are looking for a good seal not a precise
measurement
while
you are checking. If it can hold pressure for 24 hours, you
should
be
good-to-go.
Andy
-----Original Message-----
From: reflector-bounces at tvbf.org
[mailto:reflector-bounces at tvbf.org]
On
Behalf Of Joe Ewen
Sent: 01-28-2008 8:20
To: Velocity Aircraft Owners and Builders list
Subject: Re: REFLECTOR: Jeffco or not?
Grigore,
1-I believe the Jeffco is considered the preferred approach.
I
bought mine
from the factory.
2-I used a balloon to test my tank. After sealing the fuel
cap with
4"
masking tape, a balloon was connected to the vent line and
air blown
into
the tank's fuel supply line. A temporary valve in the supply
line
was
closed. I tested my tanks individually for 24+ hours.
During that
time the
balloon contracted due to temperature change, but came back
to
original
inflation when the temperature came back up. In fact one
balloon
burst from
the higher temp the next afternoon.
3-I completed one strake then worked on the second. May be
personal
preference, learn on the first and the second is usually
constructed
more
efficiently. I left the wings on until the strakes were
finished.
I departed from the manual on a couple of techniques. One
was I
used Ronnie
Brown's procedure for making the baffle templates (I believe
he
outlines the
process on his web site.) The other departure was to create
flanges
on the
upper portion of the bulkhead and baffles to eliminate the
need for
inverting the fuselage. I shared this approach with Andy M,
if he
used the
technique maybe he can comment of his success.
At the time of construction my strakes tested leak free. I
will be
retesting now that I am close to completion and hope they are
still
leak
free.
Joe
----- Original Message -----
From: Grigore Rosu <mailto:grigore.rosu at gmail.com>
To: Velocity Aircraft Owners and Builders list
<mailto:reflector at tvbf.org>
Sent: Monday, January 28, 2008 1:34 AM
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
afraid the
torsion generated by the spar may be too big without the
upper
strake.
Thank you,
Grigore
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