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The Pietenpol Project (2007)

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or     http://www.pressenter.com/~apietenp/

Dec. '07

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 first time.
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 noises.
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 together. 
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 finished


Mar. - Installing controls (front)

(and rear)



Apr. - Making airplane noises

Corvair engine purchase


Finishing up wing center section

Art gets some stick time with center section installed


Sept - Fabricating instrument panels

Sept - Fitting aluminum cowls


First spar glued and clamped


Mating spar to center section for fitting attachment


Nov 24 - Spar loaded to 1G.

Nov 28 - Adding weight to 2G's


At 3G's there was a BANG!!

The steel fitting broke under the strain


We're just amazed.

The box spar proves itself stronger than steel


Sept, '07

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 arms.
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 finished look.
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.
Steve Williamson, Pres.


With upper arms attached, lower arms are off by two inches. Welded jig establishes proper thrust line.

Cut off lower truss arms with pneumatic cutoff tool. Only original weld bead remains.

Bead material which has to be ground off. Tube ground clean and ready for rewelding.

Support trusses "fishmouthed" and ready for welding.
Mount was tack welded right in place.

Finished mount perfectly fit to our fuselage. Aluminum instrument cowls.

Rear cockpit instrument panel.

Cowl support with access door.

August, '07

When 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.

This 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.  

In the 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.

Dave 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.

With a 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.

As 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.

When 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!

The photos below captured the moment.  Art could not resist getting a little playful.

We are 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.


July, '07

...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 below).
Thank you for your interest in our chapter project.  For more information on our project visit our website at www.eaa1279.org   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.



Corvair engine as removed from flying Pietenpol.

Reassembly begins with a thorough cleaning of the crankcase.



Larry, Dave, and Art carefully remove crank and camshaft.

Reassembly begins with a thorough cleaning of the crankcase.



Hand carved Culver prop. Note the direction of rotation carved into the prop.

Fuselage with firewall bulkhead installed.

March, '07

We had excellent turnout for our Saturday morning workshop again this morning (Mar. 3).  We got our tail back in place and could not resist rolling it out for another photo.  There is some welding that still needs to be done on the axle, but in the meantime we can roll it around and show it off.  It is ready to be shown at our next chapter meeting.  We have all been waiting for the day when we can roll it out of the hangar and show it off at a chapter meeting.  That day has finally arrived.

We had a surprise visit today from chapter member Milton Black.  Milt is the owner of a brand new SportStar LSA.  He wanted to replace the factory installed Comm unit and transponder with a Nav/Com unit of his own choosing.  This left him with essentially a brand new radio and transponder which he thought we could use in the chapter project.  So he came out to the workshop to see the project in progress and to donate the Comm unit and transponder which he removed from his SportStar (see photo below). (ed. note: See Milt's SportStar here)  Many thanks to Milt for his donation.  The support we continue to get from so many quarters is refreshing and so appreciated.
Dave McPhee spent the morning prepping the wing center section for vanish.  Dave Winsett is on the hunt for some lumber to start work on the box spars.
I received some very encouraging replies on the progress that we are making on our project from Michael Cuy in Ohio.  He is on our Project Update mailing list and is following with interest the progress that we are making.  Occasionally, he replies with encouragement or suggestions.  Many thanks for his continued support as well.
Be sure to check out the Chapter Hangar section of the March issue of Sport Aviation.  We got some recognition for the work we are doing on our chapter project and our weekly workshops.  It is so nice to see so many people showing interest in what we are doing here at French Valley.  This is truly what EAA is all about.
If you would like to get involved, by all means, come out and join us any Saturday morning from 8 to noon at the French Valley Airport - Bldg. 95, Hangar 15.  See you there.
Steve Williamson, Pres.
Fuselage assembled on the gear.
Radio and transponder donated by Milt Black.
                        Center section ready for vanish.


February, '07--  

So much of the work that we have been doing on our Pietenpol project over the past year has not rendered much in the way of visible progress.  Consider, for example, the control surface hinges.  36 individual pieces.  Each piece cut, drilled, countersunk, ground, bent and welded.  And when it's done, it's no bigger than the tip of your finger.  And once it's installed, you don't even notice it.  Yet, once the hinges and attach fittings for the tail are completed, you can attach the tail and control surfaces to the fuselage and suddenly it begins to look like an airplane.  That's when you begin to see some visible progress.
    We find ourselves in a similar place today.  Three different volunteers over the past year have taken on the challenge of building the wooden landing gear legs.  The compound angles involved coupled with a bend in the fuselage belly that is unique to this particular Pietenpol fuselage frustrated one volunteer after another.  In addition to that, the legs and metal fittings seemed to have a mysterious quality to them.  We'd get one part fabricated and fitting just right, then make the next part and it wouldn't fit.  Try changing something on the second part to make it fit and, all of a sudden, the first part didn't fit any more.  And so it went.  Back and forth, back and forth.  Nothing seemed to fit right until everything fit right.
    The months just kept ticking away with the fuselage upside down and no real progress being obvious to the casual observer.  In the meantime, Dave McPhee was making steady progress on our wing center section.  I completely finished the tail surfaces, fittings and control horns and moved onto the fabricating of the control system parts.  We ordered and laced up our wire wheels and mounted the tires.  Art Froehlich worked on designing a brake system for the airplane.  We were making tremendous progress.  None of it particularly visible to the occasional visitor.
    FINALLY, I am happy to report that the landing gear fittings are all finished and powder coated.  The landing gear legs are finished and varnished.  And gorgeous they are to look at.  Quoting Art Froehlich, "They look store bought!"  It seems that patience and attention to detail has paid off.
    We had an excellent turnout at Saturday morning's workshop.  Dave McPhee, Dave Winsett, and Wendy Hinman worked together to position and glue in place the plywood underside of the wing center section.  That pretty much makes the center section ready for varnish.  Meanwhile Art Froehlich and I attached the landing gear fittings to the fuselage and assembled the gear legs and spreader bars.  By the end of the morning we were so excited to see it assembled that we could not resist securing an axle with some temporary bungies, slipping the wheels on, and rolling it out of the hangar (see photos below).  Finally, we can see some visible progress again.
    With the tail and control surfaces finished, the control system fabricated and ready for installation, the wing center section nearly finished, and the undercarriage needing only the axle to be completed, I think that we will all see some very visible progress in the next six weeks.  We have finally cleared some tremendous hurdles.  It will be very exciting to see things really coming together soon.
    Dave Winsett has constructed a sixteen foot long table in his home workshop and is ready to start work on our wing spares.  He has done some research on the construction of box spars and thinks that this is the way to go.  The main considerations are weight, strength, and cost.  In every category the box spar seems to be the better choice than either the plank spar or the routed spar.  Of course, the box spar will be a lot more work to build.  Fortunately, he doesn't charge much for his labor.
    Visitors are always welcome at our Saturday morning workshops.  So whether you want to get involved and try your hand at making some parts or you just want to see for yourself how things are coming along, you will always find some activity going on between 8am and noon Saturday mornings.  Of course, donations of labor, material, or money are always welcome also.  Involvement is voluntary, but oh so rewarding.  Why not come join us.  See you there.

Steve Williamson, Pres.