As we near the end of the year 2007 it's a good time to take a look at how far
we have come on our Pietenpol project in just the past eleven months. At the
beginning of this year our fuselage was still upside down on saw horses as we
struggled to get the geometry right on our landing gear legs. By February the
wooden gear legs were finished and varnished, the fittings fabricated and
powder coated, and we were able to roll the fuselage out of the hangar for the
Over the next month or so the control system was installed and by April we
were sitting in the cockpit moving controls surfaces and making airplane
Dave McPhee finished the woodwork on our wing center section and it was ready
for varnish. The main fuel tank was a tight fit, but with a little ingenuity
we got her in and using some temporary cabane struts managed to hang the
center section and get a real world idea of what getting in and out of
this airplane would be like.
Mid-year we had a wonderful opportunity to purchase the "firewall forward" off
of Dave Cleveland's Corvair powered Pietenpol giving us a substantial boost in
one of the most critical and expensive areas of the project. The purchase
included not only a running Corvair engine but also two more Corvair engine
cores, the engine mount, a distributor, carburetor, cowl, and prop.
By September we had the woodwork on our fuselage finished enough to varnish
the exterior surfaces (there is still some work to be done in the cockpit).
This meant that fittings for the cabane struts, the landing gear legs, the
control system, etc could be attached for the final time and the airplane
assembled for the last time until final covering. The instrument panels and
cowlings were fabricated and installed. The Piet was really beginning to look
like an airplane.
During the course of the year Dave Winsett volunteered to take on the
responsibility of building the wing spars and assembling the wings in his
garage. His research indicated that a box spar would be the strongest,
lightest, and most economical way to go. After building up one spar it was
decided that load testing the spar (to destruction, if necessary) would be a
good way to dispel any fears about flying with a spar that had been glued
Dave McPhee fabricated some steel fittings to hang the spar inverted from the
hangar "I" beams using a length of chain to simulate the lift strut. Art
Froehlich did the calculations of weight necessary to hang from stations
spaced one foot apart extending from the spar root to the tip. Weight was
calculated to simulate 1G, 2G's, and 3G's. On Saturday morning, November 24,
the spar was loaded to 1G (see photos below). Concerns mounted as the spar
began to twist and snake in ways that would not happen under normal
circumstances with the ribs installed. The test was postponed until a
suitable means of stabilizing the spar could be fabricated.
The load test was begun again on Wednesday, November 28. The spar was again
loaded to 1G. Everything looked good. Additional weight was added to
simulate 2G's. The spar was flexing at the tip, but showing no signs of
stress. The final sand bags were hung beginning at the root. Just as we
reached 1200 pounds of total weight with only 60 pounds to go, all of a sudden
- BANG!!! The sand bags struck the floor. Our hearts sank. What broke? The
spar seemed to be fine. It was the steel fitting attached to the "I" beam
that had stretched and finally broke!!! It could not stand up to the weight.
We all stared in amazement. That's 4130 strap steel!!! We needed pictures of
this! Check out the photos below.
Well... That was all the testing we needed. We were satisfied that the box
spar would make a perfectly reliable wing component. Once we get our Piet
flying, we will be comforted by the knowledge that the wings are constructed
using spars that are "stronger than steel!!!"
Our goal for next year will be to get our wings finished and get started on
the Corvair engine overhaul. Oshkosh, here we come!!!
Happy Holidays, Everyone. See you next year.
Steve Williamson, Pres.
Jan. - Getting the gear
leg geometry right
Feb. - Gear legs
Mar. - Installing
Apr. - Making airplane noises
Corvair engine purchase
Finishing up wing
Art gets some stick time
with center section installed
Sept - Fabricating
Sept - Fitting aluminum
First spar glued and
Mating spar to center
section for fitting attachment
Nov 24 - Spar loaded to
Nov 28 - Adding weight
At 3G's there was a
The steel fitting broke
under the strain
We're just amazed.
The box spar proves
itself stronger than steel
In our last update I told you about the "firewall forward" package that we
were able to purchase from Dave Cleveland of Torrance, CA. It was a fantastic
find and will save us a tremendous amount of work. However, because every
Pietenpol is a custom creation, some work is having to be done to be able to
use each of the components that we received with the purchase. The following
is a good example of what I mean.
The engine mount came right off of Dave's Piet and appeared to have been
built exactly according to the Corvair engine mount drawings included in our
Pietenpol plans. However, when we held the mount up to our firewall,
the truss arms just did not line up with the engine mount fittings on our
fuselage. (See photo below) We spent some time discussing the pros and cons
of modifying this mount as opposed to building a whole new mount for our
fuselage. We quickly decided that even if we had to modify this mount, it
would still save us the time and trouble of building a new mount. Plus any
parts or components that were "thrown in" with the purchase added value to the
purchase. Okay, so we'd decided to modify this mount. Now the question was
how do we accomplish the mod.
Fortunately, local A & P Gary Blandin put us on the right path by clearly
explaining that it was critical that we keep the "thrust line" true according
to the plan. We used some poster board to create a mock firewall, laid it on
a table, and measured and marked the proper locations of the mounting fittings
as well as the location of the "bed" tubes. Placing our mount on the poster
board, it was clear that the upper arms of the mount were close, but the lower
arms were off by two inches. We knew what we needed to do. Modify the lower
Step one was to cut the steel gussets holding the upper arms rigid. This
allowed us to attach the upper arms to the mount fittings. Step two was to
establish the proper thrust line of the bed by using a welded jig. (See photo
below) Step three was to cut off the entire lower section of the mount using
a pneumatic cut-off tool. Next, grind off what was left of the old welds to
create a clean surface to reweld. Finally, cut and "fish mouth" the lower
support arms in preparation for rewelding. You can see in the photos below
the step by step process.
Also, finished since our last update are the instrument panels (no instruments
yet) and cowlings. Note the hinged door with brass boat hardware to allow
access to the back of the instruments in the rear cockpit. This idea is
courtesy of Michael Cuy and his fabulous example of a Pietenpol. The plans
call for an open cowl support. Clearly, the door makes for a much more
The project is beginning to look like an airplane. Come check it out on any
Saturday morning 8 a.m. to noon at the French Valley Airport.
|With upper arms
attached, lower arms are off by two inches.
establishes proper thrust line.
|Cut off lower
truss arms with pneumatic cutoff tool.
weld bead remains.
which has to be ground off.
clean and ready for rewelding.
Support trusses "fishmouthed" and ready for
|Mount was tack
welded right in place.
perfectly fit to our fuselage.
Rear cockpit instrument panel.
Cowl support with access door.
the chapter launched its Builder Workshop program over two years ago, one of
the first things that we experienced was congestion caused by everyone working
on the same thing at the same time. Making wing ribs, for example, had
everyone trying to access the band saw or miter saw to cut capstrip material
while the grinder, vise, and drill press remained idle. We learned fairly
quickly that it was much easier to stay out of each others way by allowing
members to drift toward areas of interest to them. Some continued the
woodwork while others tried the hand at metalwork.
concept eventually expanded to individual workshop participants taking
"ownership" of a given component of the airframe. With the fuselage sitting on
saw horses I can remember thinking that if we could get the tail finished and
mounted, the project would begin to look more like an airplane. So for several
months I focused on making the fittings and control surface hinges to allow us
to install the tail, rudder and elevators.
meantime Art Froehlich thought that if we could just get the fuselage up on the
gear, it would look so much more like an airplane. Working with lumber yard
pine so as not to waste good (and expensive) spruce he made up some mock gear
legs. His ground work on figuring out the complex compound angles necessary to
get the gear legs to fit right eventually allowed us to get the project "on the
gear." When we were able to roll it out of the hangar, it was time for some
pictures. It was finally beginning to look like an airplane.
McPhee focused his attention on the wing center section. We intended to install
an overhead fuel tank in the center section, so we had to solicit a little help
from someone with some experience at aluminum welding. Slowly, the center
section began to take shape. Art kept encouraging Dave saying that if we could
get the center section finished and mounted, the project would look so much more
like an airplane.
newly completed home with a garage/workshop for his Jodel project, Dave Winsett
volunteered to build up the box spars for our wings. A 16 foot long flat and
level table would come in handy when he was ready to build the wings for the
Jodel. He used some MDF to make up a jig and went to work on the first of four
spars. Art intends to make up a test jig so that we can load up the finished
spar to simulate three (maybe four) G's. This should satisfy everyone of the
strength of the box spar concept.
reported in the last update we recently purchased the "firewall forward" from a
flying Pietenpol. The engine mount does not exactly fit our fuselage. We are
working out a process to modify this mount to fit rather than make a new one.
At last Saturday's workshop we were able to successfully attach the top arms of
the mount to the fuselage fittings. The center line and thrust line are
perfectly positioned. Now we can focus on the modification to the bottom part
of the mount.
Dave McPhee arrived, he announced that he had the cabane struts and center
section ready to install. In a few short minutes we had the bolts in and stood
back to admired the project. Time for another picture. We rolled the airplane
out of the hangar and each took our turn sitting in the cockpit and making
airplane noises. We all had the feeling that the project was finally beginning
to look like an airplane!
photos below captured the moment. Art could not resist getting a little
at that point in the project where the months of working on individual
components are materializing into some very visible progress. Thanks to the
effort and support of many members we can see the light at the end of the
tunnel. We welcome the participation of anyone who would like to join in the
adventure. Come on out and get involved. We are there every Saturday morning
from 8AM to noon. With the help of many hands the project will get done. See
you at the airport.
Art Froelich takes his turn in the cockpit.
Art jumps in to hand prop the engine.
Dave McPhee gets and idea of how the engine and prop will look.
Art "flies" his first passenger.
...Those of you who have been following the progress of our Chapter
Pietenpol have watched as we make slow but steady progress on the project.
Every once in a while we get a little boost. Sometimes it's in the form of a
substantial surprise cash donation from a supportive member. Sometimes it is
a lead on a much needed part or component. Such was the case when Jim Pyle
alerted me that one of Chapter One's members was buying a flying Pietenpol,
but was not interested in the Corvair motor that powered it. He thought that
we might be interested in the engine. A few phone calls put me in touch with
the seller who told me that if we were interested, we could have the running
engine (plus two cores), the Stromberg carburetor, the dual point distributor,
the motor mount, the aluminum engine cowling, and the propeller. Holy cow,
the whole firewall forward?!! What a find!! We were there the next day with
two pickups and some cash.
It turns out that there was quite a story behind this airplane and its
engine. The owner at one time operated a halfway house for youth offenders in
upstate New York. Being a pilot he came up with the idea of starting an
airplane building project as a means of focusing the energy and attention of
these at risk youngsters. The State funded the project and pretty soon these
youngsters were learning to cut and glue wood, bend and weld steel, read and
interpret plans, and all the other things that go into building an airplane.
This was between 1970 and '75.
Fortunately, the builder was able to have a few telephone conversations with
Bernie Pietenpol himself before he passed away in 1975. Bernie encouraged him
to use a Corvair engine to power the airplane. So that was what he did. He
purchased an engine from a wrecking yard and mounted it on the airframe just
as it came out of the car - cooling fan, dual carbs, and all. He did
fabricate a carb heat box (remember, this was New York). He purchased and
installed a Hegy prop. And once it was completed, that's the way it flew for
the next ten years.
The builder eventually went to work for Toyota who promptly relocated him to
sunny Southern California. Before leaving, he contacted the state to ask
about the disposition of the airplane. They told him in no uncertain terms
that what they funded was a jobs training program for at risk youth. They
wanted no part of the airplane that may have been produced as the result of
that program. NO THANK YOU!! They wanted no part of that liability. So the
builder happily took the airplane with him where it came to roost at the
Compton Airport (later moved to Torrance).
In 1985 the Piet owner met a fellow named John Culver who told him that he was
in the business of carving wood propellers for a variety of airplanes. At
that time amateur builders using the VW-based Revmaster engines represented a
big market for his props. "Do you make anything for a Pietenpol powered by a
Corvair engine?" he was asked. "No," came the answer, "but it sounds like an
interesting prospect. How about taking me for a ride."
Culver took three pages of notes as the Piet pilot flew a variety of in-flight
maneuvers. Three weeks later John showed up with a beautifully carved and
finished wood prop. The prop was installed and off they went to test the
performance. The Piet owner tells us now about how stunned he was at the
improvement in performance. He became an instant convert to Culver Props.
Unfortunately for John Culver most Pietenpol builders were either using Ford
Model A engines for nostalgics sake. Or using proven aircraft engines like
the Continental A-65 for reliability. There just was no market for this
particular prop. (Remember, the Corvair engine turns the opposite direction
from every other airplane engine. Thus, the prop could not be used except on
a Corvair motor.)
Now you see what makes the purchase of this particular "firewall forward" such
a fantastic bargain. We got as part of the deal what is essentially a "one of
a kind" hand carved prop by John Culver (see photo below) designed to maximize
the performance of a Pietenpol Air Camper powered by a Corvair engine. Not to
mention the time that we save by having a ready-made motor mount and cowling.
As the result of extensive research by William Wynne in Florida on the use of
Corvair engines in airplanes we have decided to completely overhaul the
engine. This is a good thing. Through his research Wynne has determined that
the Corvair is a good engine for use in aircraft, but not without some simple
and inexpensive (but essential) modification to the engine as it came from
General Motors. These modifications include: hardening the crank with an ion
nitriding process, exchanging the cast pistons with forged pistons (forged
connecting rods were standard), using chrome piston rings (preferably Perfect
Circle, no gap rings), and converting the distributor from a single point to a
dual point/dual coil ignition system.
By the end of this year we should have our fuselage finished (see current
photos below) and a "zero time" engine installed with propeller and cowling.
Our wing center section with fuel tank will be installed. And we will be
focused on the completion of our wings (see photos of "box spar" lay up
Thank you for your interest in our chapter project. For more information on
our project visit our website at
If you would like to participate in this adventure, please feel free to visit
the workshop on any Saturday morning, 8AM to noon. The location is French
Valley Airport, Building 95 (at the south end of the field), Hangar #15.
Steve Williamson, Pres.
engine as removed from flying Pietenpol.
Reassembly begins with a
thorough cleaning of the crankcase.
Larry, Dave, and Art carefully remove crank and
Reassembly begins with a thorough cleaning of the
Hand carved Culver prop. Note the direction of
rotation carved into the prop.
Fuselage with firewall bulkhead installed.