My New Lazair III

My New Lazair III

Monday, November 19, 2012

The Best Laid Plans of Mice and Men……

One of my all-time favorite movies, Randy Quaid did a fantastic job as Lenny, so much so, and as I was quite young when I saw the movie, I thought for years he truly was mentally disabled. And Berretta played his part very well too.

I have made the first rigid polyurethane ribs from my rib mold. The ribs have turned out to be very strong and the foam bonds very well to the aluminum as expected. However there are some aspects to the process I did not anticipate and it looks like I am going to abandon this process.

The foam is much stronger when expanding than first thought. In my research I had been warned that the foam had the ability to exert great pressures against any enclosing structure (probably a uni-directional force as opposed to a true pressure). So I expected the first rib to lift the top plate of the mold and create an overflow between plates. Therefore I put a 20lb weight on the top plate, but alas it wasn’t enough and added an additional 20lbs too late in the cycle to make any difference. Because I didn’t know exactly how much foam to put in the mold it was a big guess on the first pour. I mixed 150ml of A and B, 300ml total on the first pour. The foam lifted the top plate nearly a half an inch. But no big deal as this was just a test anyway and it would give me a good idea of how the foam would stick to the top plates. Once the foam was cured I removed the top plate quite easily. It gave a bit of resistance at first but then popped loose. But O MY! The static electricity it made! Several good zaps before I got it completely off. The overflow had to be chipped away until I reached the Inside Mold Line (IML). However the rib would not slide out of the profile plate even after chipping the overflow from both sides, I had to take a hacksaw blade and very carefully cut it out. After removing the rib the profile plate cleaned up rather easily with a putty knife. The foam doesn’t actually adhere to the HDPE, it appears to be a purely mechanical attachment to the tooling marks left in the material during machining.

I lined the profile plate with a 1” aluminum strip and used 100ml each of the foam components (200ml total) for the second pour. The blue tape is to hold the aluminum strip in place. After mixing the foam and pouring the mix into the profile plate you have to swish it around to cover all the bottom of the mold area, it doesn’t flow well once it is expanding. I quickly put the top plate on and added the 40lbs of weight. I was astonished to see the top plate had lifted about 3/16” when I went to remove the mold. So since this mold still had overflow I had to chip the overflow away up to the aluminum strip. The rib then slipped out of the mold with a bit of persuasion. This second pour could be a viable rib but it is too thick. It turned out exactly as expected, the capstrip is well adhered, the rib is extremely strong and is a third heavier than the original Lazair rib, but is a third thicker too. The new ribs will likely be nearly the same weight as the originals once the thickness is under control.


Several unforeseen difficulties have arisen that threaten this process. The primary one is the foams ability to lift a significant amount of weight while expanding; the second is the relatively small amount of foam necessary to fill the void. The lifting of the foam drives the need to have very accurate amount of foam mix poured in the cavities, coupled with the already small amounts of foam means that for this to be a repeatable manufacturing process the foam mix must be carefully controlled. With already small component volumes this becomes very difficult with equipment at hand. If the foam lifts the mold plate and overflows removing the rib from the mold becomes too labor intensive to be economical and the rib requires extra rework to make it a uniform thickness and meet quality controls. Therefore, unfortunately, I am abandoning this process and looking to a more traditional method for making ribs.

The new method will be to buy the foam pre-expanded to a uniform thickness and route it to profile with a template and flush cut router. The drawback to this method is the foam boards are rather expensive, somewhere on the order of $200.00 in materials for a complete shipset. It may turn out to be a wash when the reduced labor is taken into account, but this means the rib capstrips will have to be bonded in a separate operation. I wonder if JB Weld would work. I’ve already purchased a suitable router table and router. I need to make some templates and order some foam.

In other news I have pictures of the 2SI engines that are for sale. They are 2SI 215F’s with Prince P-Tip Props, you can find info on them on the 2SI website. If interested please contact me. I am also working on a wheel and brake replacement. I am having adaptor bushings machined now and will post pictures as that project progresses.


More Next Time,


Saturday, October 13, 2012

Old Rusty Bits for New Shiny Parts

As promised...more updates.
As I continue to unpack I make fresh and exciting discoveries on a continuing basis. Along with the tooling that makes the seat bows, I think (and hope) I have discovered tooling that presses the upper and lower channels for the engine pylons. The upper channel was considerably worrisome as it is not easily reproduced without proper tooling and I really didn't want to reinvent the wheel so to speak and develop new tooling, even though  I am in several different areas (like the wheels). Dale's design for these parts was at once elegant and simplistic, always a hallmark for lightweight strong structures. Making a proper press fixture for this part is expensive. The lower channel is relatively easy to make with a hammer and form had we needed. But we have the tooling, it needs some TLC to be sure but at first take appears to be serviceable.



We also found some other punches and tooling and are sorting those out as well.

Progress is being made, slowly but surely. I have to remind myself the hare won the race.

More next time,

Monday, September 10, 2012

New Digs

Well I’ve finally jumped off the deep end. I guess the old saying of “Put your money where your mouth is” has come into play. I have leased a small T-hangar at the local (if you call 30 miles away local) grass strip. I am unloading all the tooling for Lazair stuff and trying to figure out what all these old rusty bits do, or used to do. So far I’ve found the tooling used to make the seat bows, a crude but ingenious bit of tomfoolery, and am figuring out how to use it. There are bits and pieces of all sorts. In the discovery we’ve come across a roll of Tedlar, looks to be in good condition after you take a few feet of damaged and aged material off. I’ve found several replaceable propeller blades, perhaps some testing was going on with ground adjustable props? There are 3 Rotax 185’s with Bi-props, and two 2SI engines with Prince P-Tip props. But the crowning jewels, besides a complete Series 3, maybe it’s an Elite airframe, are two absolutely beautiful sheet metal floats for the Lazair, pics below. Whoever made these put a supreme effort in, they are wonderful works of art in aluminum, and very light weight. I don’t have a scale yet but they can’t be more than about 7 lbs each. These were truly a labor of love and craftsmanship par excellence and very labor intensive indeed! As we are not going to offer float options in the foreseeable future we are offering these floats for sale as well as the engines and propellers. There is also a set of original wheels and brakes for sale as well.


Immediately we are going to work on making ribs out of our mold, getting the first set of D-Cells ready with the beefed up spars and fuel tanks in the leading edges, and new landing gear main wheels. Please contact me if you’re interested in any of the parts.
As the weather cools off here in south Georgia I will be to working on getting this project up and moving and will post updates more often as we make significant accomplishments. Thanks for taking time to have a look see.


More Later,


Friday, July 13, 2012

A Lifetime Doesn’t Seem Like Enough

While it is never my intention to use this forum as a vehicle to air out my personal life, I have noticed 5 months have gone by since my last post and there have been a small but steady stream of people repeatedly visiting the site from all over the world. This indicates there is some number of folks still interested in my little slice of heaven. So to those watching I have not been slacking off. Between February 27 and April 6 I lost 3 very important members of my family (Grandmother, Mother, and Father) all two weeks apart like clockwork. And although their deaths were not related; one has to wonder, given their life stories, if their fates were not somehow connected. But that is a story for another time. 

As you may imagine these events have taken a heavy toll emotionally and spiritually, and honestly I just haven’t had the gumption to work on the Lazair project lately. But it is time to put that behind me and get going once again. While I don’t have anything noteworthy to post just yet, I wanted to take a moment and thank those folks all over the globe that have checked in to see if something new had been put up. The steady tick of the visit counter has inspired me and warmed my heart to know that there are a few people in the world that would still be interested in what I am doing even after months of silence, and to those people I say thank you. 

More to come very soon,

Monday, February 6, 2012

More on Fuel Tanks

One Down, One to Go

Another Town and One More Show…..

Those of you who are fans of eighties music will get that reference.

This update is twofold; one fuel tank is finished and we have pictures with a piece of leading edge skin to show the fuel filler neck installation, and we have our first rib mold. 

This first picture shows a top view of the fuel filler neck we have selected. It is a glass filled nylon unit with a nice red screw on cap. As you can see in the pictures it is fitted from beneath the leading edge skin so just the filler cap is visible. It is a nice flush install; the cap is domed and sticks up above the skin just slightly. All in all a fine solution to the filler neck problem. These necks are lightweight and low cost, all pluses in this application. If a customer wanted a polished leading edge we can swap out the red cap with a polished stainless steel cap.


The next picture illustrates the filler neck installation from inside the D-Cell. The screws are obviously too long and will be replaced with stainless screws of the proper length at the final installation. The white corrugated tubing is nylon marine bilge pump tubing, really great stuff, gasoline resistant and flexible. The tubing is sealed to the filler neck with gas proof sealant and held in place with a screw (not visible in photo). This installation has been leak tested and everything is good to go.

The last pictures show a more detailed view of the gas tank construction than the last blog. The outboard cap has a nylon fitting installed for the filler neck and tubing to attach to. 

The inboard picture shows the vent tubing and fitting at the top of the tank and the fuel outlet fitting, tubing, and primer pump/check valve with tubing going to the center cross-over and to the engine.

The following pictures show our beautiful new CNC cut rib mold. It is 1” HDPE machined to the rib profile. The second and third pictures show an original Lazair rib fitted into the mold. It is a nice tight fit just like it should be. 

The premise of the mold is to line the profile with aluminum capstrips and cast the mold with 2 lb/cu ft rigid polyurethane expanding foam, let it set up and pop the new rib out of the mold. The polyurethane foam will adhere to the aluminum capstrip tenaciously, and the foam is chemical resistant (including gasoline) and is considerably stronger than the original polystyrene (Styrofoam) ribs. This is a quick, easy way to make ribs and they will all be exactly the same each time. I’ll do another post when we cast the first rib…stay tuned.

More Next Time,