Building Metal versus Fiberglass Airplanes

From: Randy J. Pflanzer (rpflanze@iquest.net)
Date: Mon Jan 29 2001 - 14:34:42 PST


--> RV-List message posted by: "Randy J. Pflanzer" <rpflanze@iquest.net>

A number of folks have asked me to post my opinions regarding the
differences in building a RV type aircraft versus building a fiberglass
airplane. Since I have built one of each, I will share my perspectives
on the relative pros and cons of each. Please remember that these are
my opinions only and they are worth what you paid for them. If you want
to disagree with me, go for it. My skin is pretty thick.

First, let me say that not all fiberglass airplanes are alike. I built
a Long-EZ, which is to say that I had to shape foam cores and apply
fiberglass cloth over it. This is definitely more work than building an
airplane where the parts are vacuum bagged like a Glassair. The new
cowlings on the RV series are examples of vacuum bagged parts.

Each type of airplane has its good things and its bad things. On metal
airplanes, you can stop at any point in the construction process to eat
dinner or go to bed. When you finish putting the skin on, you are
essentially finished with the part except for scuff, prime, and paint.
It takes longer to build a part out of aluminum than it does out of
fiberglass, but you make up for it during the finishing process. The
temperature of the building area is not critical during construction of
a metal airplane. If you want to change the location of something on a
metal airplane, you just rivet it on in a different location. Can't do
that on a fiberglass airplane. You have to provide for hardened
structures within the fiberglass so you have something solid to bolt to.
 It is very difficult to build compound curves in metal, but it can be
done with an English wheel and some experience. Also, you can paint
your airplane any color you'd like. Always wanted a Ferrari Red RV? No
problem. Finally, it is easy to inspect the construction of a metal
airplane. Open her up and look at the riveting technique.

To counter those points, a fiberglass airplane goes together much
faster. Complete the lay-up, trim and you're done. No measuring,
drilling, deburring, dimpling, and riveting. However, once you are done
with the construction you are only about half done. Finishing is more
time consuming but you learn to develop techniques for doing large areas
at once. Buy lots of sandpaper. Building in the winter is a problem
because you have to keep the shop temperature above 70 degrees while the
fiberglass cures. Also, you can't stop in the middle of a lay-up. If
the plan calls for five layers of cloth then once started, you must work
through until the end. You must plan your time in the shop more
carefully. You can do things in fiberglass that you could never do in
metal. For the most part, you can get very creative with fairings, wing
tips, etc to personalize your airplane. If you walk the flight line at
Oshkosh, you won't find two EZs the same. Except that they are mostly
painted white. You need to stick to a light color to avoid heat buildup
underneath the lay-up and to avoid ultraviolet degradation of the foam
cores. Also, IN MY OPINION, a fiberglass airplane of the same
dimensions will be lighter and stronger than a metal counterpart,
although this is dependent upon your lay-up techniques. Finally, it is
easy to screw up a fiberglass airplane and make a structure that is not
very strong. Use the wrong cloth (yes, there are different types) or
run the fibers in the wrong direction and the structure isn't worth
s**t. Once painted, you'd never know the difference until it fell off.

There are probably a dozen or so factors that I've forgotten to mention,
but I'm sure others will chime in. I greatly enjoyed building both,
although I got really tired of the finishing work on the Long-EZ. I
loved flying both as well. Personally, I can't recommend one over the
other. I'm looking at another project. I'll look at the four-place RV
if it comes out in the next year or two. If it doesn't, I'll probably
go with a Velocity.

If you have comments, feel free to send them to me directly at
rpflanze@iquest.net.

Randy Pflanzer N417G
RV-6 (115 hours)

_-============================================================
_-= The RV-List is sponsored by Matronics and through
_-= the generous Contributions of List members.
_-============================================================
_-= List Related Web Sites
_-= Matronics: http://www.matronics.com/
_-= List Specific: http://www.matronics.com/rv-list
_-= Subscription: http://www.matronics.com/subscribe
_-= Search Engine: http://www.matronics.com/search
_-= Download: http://www.matronics.com/archives
_-= Contributions: http://www.matronics.com/contribution
_-= Other Lists: http://www.matronics.com/emaillists
_-============================================================
_-= Secure Online Ordering Now Available at Matronics!
_-= Place your order online and save 5% -
_-= http://www.matronics.com/order
_-============================================================



This archive was generated by hypermail 2b29 : Tue Jan 30 2001 - 07:07:38 PST