My New Lazair III

My New Lazair III

Sunday, October 27, 2013

The Wheels of Change on the Bus Go Round and Round, Round and .......

A Wise Man Can Hear Profit in the Wind

Ferengi Rules of Acquisition 22

Busy, Busy, Busy…….There is never enough time in the day.
Many progressive things have come to pass in the few months since my last post. I have acquired a very nice Lazair Series III from Michigan and have been working to get it in airworthy condition. In addition to typical maintenance issues on this bird I have installed a set of Black Max Brakes and it has much improved ground handling. Have a look at the pics below to see the mods. If anyone is interested I have a complete kit available to do the conversion. Therefore I now have two complete sets of original Lazair wheels and brakes available for sale with nosewheels (rotating skid). These first two pictures are before the brake mod, and after.

The Black Max Wheels give the Old Girl a sporty look don't you think? The extra wide stance reduces side sway when taxiing too.

The brake mod has a small problem, with a very beneficial fix. The master cylinder shaft hits the forward fuselage tube and you lose about 1/2" of rudder pedal movement.

The fix is to add the rudder belcrank extension you see. This extension adds one inch to the rudder pedal throw, increases the total rudder deflection and "speeds up" the rudder pedal movement, i.e. more throw per degree of pedal travel. This is beneficial because the Lazair were always wanting for more rudder authority.

Here are some development pictures of the brake install.

And some photos of the Axle and Caliper installation.

The last pics show the pedal mods needed to get enough throw on the master cylinders. I installed a toe tube on the pedal to give more throw and to widen the brake pedal, I always thought they were too narrow.

In addition to gaining an extra bird I have been progressing on the Mark IV. I have installed the endcaps on the ailerons, sorry no pics right now. Also I have built a test stand to run-in the Evolution Radials and have run the first one. You can see a poor quality video here: I took this video from my cell phone so it’s not the best but you get a good look at my test stand and hear the engine run. These are real hoss’s for powerplants and are really going to liven up the Mark IV. I have a 32 x 12 Valley View break-in prop on right now and this engine spins the devil out of that thing. I will need to make an external electric starter as hand propping this beast is both dangerous and tiring. Maybe a converted marine outboard starter motor? Taking suggestions on this one.

More Next Time,

Wednesday, July 17, 2013

Ailerons and Engines
Yanking and banking soon possible
If you have good health, consider yourself lucky. I have had some health challenges of late and am far behind schedule, but enough about me.
We have ailerons and engines. Before the doom and gloom set in, and after my last post I made a set of ailerons and they are quite handsome, if I do say so myself. The construction method is somewhat similar to the wing ribs, foam rib cores with sheetmetal capstrips. A 1.5” tube is the spar and a ½” tube for the trailing edge with sheet metal to make a pointy edge. I designed the ailerons on Solidworks and had a full size template printed out. I glued this to a hollow core door to build on, just like my RC modeling days. I made rib locators out of blocks of 2 x 4 and glued them in place. This holds all parts in location and all that is necessary is to drill the rivet holes and pop them in place. The ailerons are very strong in torsion, more so than I expected, without using triangular gussets like on the Lazair. In the pictures the trailing edge sheetmetal is only sitting in place, it is not permanently fastened yet. You can see the end caps, which also are not finished, they need trimming and riveting. A unique aspect of these ailerons is they are symmetric so both LH and RH ailerons can be built on the same jig. To move from one side or the other all you do is install the control horns (not pictured) on the top or bottom of the spar tube to get the alignment to match the aileron control rod, which will exit the top of the wing on the Mark IV.

This symmetric construction required a different pivot setup than the original Lazair. If you will notice the pivot is in the center of the spar tube, via a bushing and stud setup. You will also notice a “pillow block” type bearing on the stud. This gives an illustration of how the aileron pivots. A bearing is installed on the inboard (#6) rib and the outboard tip rib. The inboard stud will float in the bearing. That is it is free to slide inboard/outboard because the stud is considerably longer than need be and will actually penetrate into the inboard rib about an inch, a hole in the rib allows for this by design. The outboard rib will constrain the aileron as it will have a bolt as a stud and will capture the aileron inboard/outboard motion. This end is covered by the wingtip and will not be seen except during maintenance. To install the aileron you will slide the inboard stud into the bearing at an angle until the aileron will fit in the aileron gap of the wing. Lift the aileron into place and align the outboard bearing. Install the bolt and safety. Install the wingtip, connect the aileron control rod, repeat for the other side.


Engines, The Heartbeat of the Bird
I think I posted some time ago that I had intentions of using Hirth F-36 engines on this first Mark IV prototype. However fortune has smiled on me and I have been able to acquire two brand new, in the box, Evolution 7 cylinder 260cc four stroke engines. They are sitting in my closet right now and every now and again I have to open the door to look at the boxes and smile. These engines are an incredible work of art in metal. Check out the website and youtube video links below: 
I expect to be the first ultralight with twin radial engines. Maybe a world record? Probably not but really cool never the less. I am making a test stand to break these engines in. I plan to post videos of them running as soon as possible.
Propellers are a beast of another color and have proven to be more troublesome than you might think. I could certainly get propellers for these engines from the RC world, but I think they look out of place on the Lazair, too thin. The problem of what pitch to use is also problematic. I don’t want to buy a dozen props to figure out which pitch is right, that’s expensive research. I really wanted a ground adjustable prop and in particular a three bladed adjustable prop. After many years of research there was only one choice, Solo Props. 
So right now Solo is building two sets of 32” 3-blade adjustable props. Should be ready in the next month or so. They look just like Hamilton-Standard props off a DC-3.
More next time,

Tuesday, February 19, 2013


Ribs, Ribs Everywhere, and Not a Drop to Drink.


The second generation ribs are in and they are very nice I must say. See pics below. These ribs are made from rigid polyurethane foam, the same material I tried to cast ribs from. These are made from 1” sheet foam routed to shape and capped with an aluminum capstrip top and bottom. I had to make wood templates by hand from my CAD files so it took some time since the last post. The cap strips are .020” aluminum bent into a “C” channel and then hand fluted and fitted to each rib, then attached to the foam with contact cement, a time consuming process. The ribs are painted, white in this case, with gloss exterior latex paint to protect them from UV damage. This particular rib weighs 13oz, I haven’t weighed an original rib yet but they “feel” about the same. I suspect it is slightly heavier with the paint. These ribs are much stiffer than the original ribs and I have to say I am quite pleased with how they turned out.

Finished Rib

Foam Blank painted with acrylic latex paint

Upper Capstrip, formed to match upper surface contour

Lower capstrip

Upper and Lower Capstrips fastened with two stainless rivets


Corner Detail

A youtube video documenting the rib making process is in the works. Perhaps it will be of some help as part of a video construction manual.

I am currently making the sheet metal brackets that attach the ribs to the spar and trailing edge. Complete wings are now within a foreseeable future.
More Next Time,