Mark IV

Though the Lazair design has not been produced since 1984, a few have made attempts at re-launching the design. One attempt was made back in 1995 with Wind Craft in Indiana. See article here. That didn’t pan out. Currently Gene, down in Georgia is attempting to make the final go at it! We wish him the best of success.

The following information was taken from

“The Lazair project is moving at an incredibly slow pace. Although some things are happening, any visible progress is invisible. We have obtained all the tooling, what there was of it, from Michigan (October 2010), and we have all the necessary rights and licenses in place to sell under the Lazair name (HUGE sales importance). We have been capturing the Lazair design in Solidworks (parametric 3D CAD software), and are updating a few items to take advantage of modern manufacturing techniques and materials. The end product will appear to be exactly like the Elite or Series III Lazairs, however there are several major differences; strengthened wing spars (for 350lb pilot), different main landing gear wheels and nosewheel with better brakes, relocated fuel tank (from behind seat to inside leading edge D-cells), Hirth F-36 engines, BRS recovery parachute, and rigid polyurethane foam for the wing ribs. It will be named the “Mark IV”.

Design Issues
Ultraflight released very few drawings for parts (only tubes) to the public, there is some debate as to how much of the design was captured. In making Solidworks models of the Lazair parts everything is pretty straight forward and simple to model, although very time consuming to reverse engineer, except for the wing ribs. I asked Dale how he designed the rib profiles, his answer was he hand lofted them using parts of other ribs he was familiar with and developing the lines until they were pleasing to his eye. Very creative and yet another indicator of his natural ability as an aircraft designer. However this becomes a nightmare when trying to model the ribs in 3D CAD. So I had a couple of choices; I could simply model something that looked OK but wasnt really representative of the real airfoils, and therefore couldnt be used as a base for modern CNC manufacturing techniques to make templates, I could send the ribs out and have them Z-scanned and a point cloud for each developed and make models from that (really cool technology, but very expensive), or I could trace out each rib and graphically extract coordinates and get some useable data to start from (the old school method). I chose the latter course ( I never knew how important those kindergarten tracing lessons were going to be). I created large graph paper and layed each rib down and traced the profile. I then took a 6 inch scale and hand computed each coordinate in half inch increments. A labor of love to be certain, but when finished, a few months later, I had something that no one else on earth has, not even Dale, Lazair rib coordinates. I loaded the coordinates into my CAD software and “wah-lah” I had 3D models of the ribs. After some adjusting and smoothing for measurement inaccuracies I now have beautiful rib models that I can send out and get templates made (molds actually, explanation below).

Why move the fuel tank, and why that drives new rib material and the need for accurate rib models.
The decision to relocate the fuel tank is two fold. Firstly the traditional location is a pain in the back to refuel (literally), you either have to remove the fuel tank (which means lifting it back into the holder when its full of fuel ~30lbs), or contorting your self and holding a gas can at an awkward angle to refill, both of which are extremely hard on your back. Some folks developed special hoses and other things to make the job easier, but this means you have to take that stuff with you if you plan on refueling off your home field. The other reason is to reduce the total lift height from the fuel tank to the carburetors. Although a good pumper diaphragm carburetor will lift the fuel, any small leakage in the fuel line, primer bulb, or joint in the fuel line will cause fuel starvation. It was a significant problem as evidenced by the Lettair Service bulletins.

Relocating the fuel tank to the leading edges makes it much easier to access and refuel and drastically reduces the lift height from nearly 24″ to about 6″ max. But what happens when gasoline is spilled into the leading edge when refueling? This is a major concern and has many facets to overcome. The largest problem to overcome is the fact that gasoline will melt polystyrene (i.e. the blue foam the original ribs were made from), and it could have and adverse effect on the tapes used to hold the covering material on. The design changes to overcome these obstacle are rigid polyurethane foam for the rib material, this is an excellent substitute for polystyrene, and scuppers near the fuel inlet to capture and absorb any spilled gas before it gets to the tapes. Polyurethane foam has the same density as polystyrene and is rigid. Polystyrene is semi-rigid but has very low compression strength. Polyurethane foam is inert to all chemicals, but is not UV resistant (easily overcome with a coat of ordinary inexpensive latex housepaint). Fabricating ribs from 2 lb density polyurethane foam was a bit of a head scratcher to overcome. Polyurethane foam boards in 1″ thickness are available, but not locally and they are quite expensive. Looking around for a solution found expanding foam (often referred to as A/B foam) and is quite readily available and affordable from the marine industry. So a plan to cast the ribs from expanding foam was hatched, but to cast something you need a mold. I could have just got a 1″ thick board and made female molds by simply tracing the original rib profiles, but that just didnt cut in my world. I wanted ribs that were accurate to the original Lazair ribs, but were repeatable if I ever needed to make new molds. So right now shiny new HDPE molds are being CNC cut from the hard work that was put into capturing the rib profiles in CAD and new polyurethane Lazair ribs will be available soon.

Whats the hold up? When will we have new Lazairs rolling off the assembly line?
This is the question I am asked all the time when someone gets wind of what I’m up to. And the answer is…..I wish I knew. I have basically everything needed to make new Lazair parts and whole ultralights except for a place to work in. My little town of Brooklet, Georgia and the larger Statesboro area has few offerings of spaces large enough to set up shop in, and what is available is priced far out of my meager budget. I am still vigilant looking for shop space, but until something comes along I will keep plugging away in the garage.

There will be more to come on the Blogspot page as I get used to this means of communication, check back from time to time. Until then email me at



A Brief History

I flew Lazairs while in High School in the mid-late eighties (Gene). We had a Lazair dealer in my hometown and I really like the design of the Lazair. I sought to acquire the factory and produce new Lazairs at the end of the nineties but was unable to make a deal at that time. I analysed the Lazair wing as a class project while in college for my Aerospace Engineering degree and thought that new Lazairs would be “relatively” easy to make being an A&P Mechanic with much aircraft structures repair and overhaul experience.


I finally acquired the rights to manufacture under the Lazair name from Dale Kramer, and then the Lazair factory (what there was of it) in 2010.


Why a new model?

1. To differentiate what I am making from the previous models

2. To make changes that I deem necessary or beneficial

3. To allow Dale to make Series III airframes for his E-Lazair without confusing anyone about the different models.


What Changes and Why?


1. When Dale made the original Lazair wing his sheetmetal brake was 4′ long and therefore he had to make 3 joints in the constant section of the wing. Every joint is a potential point of failure and eliminating joints makes for a robust wing. A 12 foot shear and press brake are a hard thing to find, and are very expensive to have people make things on. So I redesigned the wing spar to not require any sheetmetal bends. The spar is made up of a .050″ 6061-T6 shear web (constant section is 7″ X 144″, tapered section is 6 feet long tapered from 7″ to 2″). The spar caps are 1″ X 1″ X .125″ 2024-T3 Angle and are continuous from root to tip both top and bottom (i.e. no joints) There is a joint in the shear web where the spar taper begins and is reinforced with a .050″ 6061-T3 doubler. The spar is riveted together with AN470AD5-XX rivets. This spar is designed, and analysed for a 350lb pilot and gross weight of 650lbs with a +4,-2 published G-Rating.


2.The Rotax 185 engine is difficult to get and very costly. The better alternative is the Hirth F-36 which is based on the Solo 210. It is a very similar engine to the Rotax 185, is available for ultralight use, is affordable, and gives 15hp which is necessary for the higher gross weight. Other engine options are available, particularly 4 stroke radials.


3. The fuel tank on the Lazair is difficult to access and changes the center of gravity significantly from full to empty. I decided to move the fuel tank to inside the leading edge of the wing for ease of access and to reduce the CG swing. The net effect of this change is a slightly (about 1/4″) more forward CG when the tanks are full as compared to the original CG when empty. As the Lazair is a bit tail heavy in general this change will result in a negligible difference in flight and is well within the acceptable CG limits for the wing.


4. The wing ribs on the Lazair are made of blue insulating foam (polystyrene) which melts when in contact with gasoline. The fuel tank change forces a material change in the wing ribs, I have chosen 2lb density polyurethane foam because it is available and is gasoline resistant and stronger than polystyrene. I have added aluminum capstrips to the ribs, like the original lazair except my capstrips are bonded on and add significant strength to the ribs.


5. The Lazair D-Cell nose ribs were also made from blue foam and were glued in place. Over time the ribs fell over because they broke at the glue line, or the glue detached. I have designed and produced aluminum hydropressed sheetmetal ribs which also serve as the mounting mechanism for the fuel tanks. They are much more robust than the original foam ribs.


6. The original push-pull flight control system is sloppy (lots of play) and is fiddly to make (lots of parts). I am replacing this with push-pull cables like used in the marine industry. They will be more affordable to manufacture, will provide “tighter” control system, are more weather resistant, and easier to install compared to all the bellcranks.


7. The original Lazair ailerons are discrete assemblies, one for the right, one for the left, and are twisted. I have made a minor alteration to the #6 wing rib profile which have little effect on flight characteristics but allows the ailerons to be made flat and symmetric side to side.


8. Other Miscellaneous changes: New wheels and disc brakes, fiberglass wingtips, alternate covering options.


9. The lift struts are changed from 1 1/4 round tube to Streamlined tubes. These are the same tubes used on the CubCrafters SportCub aft lift struts and are WAY overkill for the loads from the Lazair. I thoroughly analysed these tubes while designing the SportCub and have every confidence in their ability.


Proof of structure

The new spar design is obviously much stronger than the original Lazair just by considering the materials and thicknesses involved. However I have done a “classic” bending analysis on the structure and an Finite Element Analysis (FEA) which shows the wing is far stronger than the “published” rating of +4/-2 G. I will not state exactly what the wing will take, because someone will try to fly it to that rating to see if it will take it. Or more likely they will think they can do aerobatics and will end up killing themselves. +4/-2 G is adequate for what the type of flying the Lazair is intended for. I will do a physical proof test when that time comes. It will not be done on the first prototype, as is normal practice, it will likely be done on the second wing as there have been some design changes (weight reduction) that are not incorporated in this first wing.


The intent of this work is to produce a Lazair that flies the same as the original, but has capacity for a larger pilot. The changes I have made will have very little effect on the flying characteristics but will allow for easier manufacturing. The Lazair was very well designed originally, some manufacturing constraints came into play to make the wing structure more complex than was necessary (i.e. so many joints), and I am incorporating some changes that improve the manufacturability/cost, accessibility, or durability.



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