My New Lazair III

My New Lazair III

Sunday, August 31, 2014

48 Weeks Till Oshkosh

We Aint Got No Velocity Stacks....

As I was flying around one day in my Lazair, minding my own business, my right engine decided it wanted to speed up all by itself. Apparently I was flying too slow for its liking. I was puzzled by this as I prefer my engines to tow the line I lay down. As their Captain I am in charge and rather enjoy my engines following my command. I do not like engines having a mind of their own. 

In investigating why this engine was able to determine its own power setting I discovered that under the right conditions, mainly a sideslip or a crosswind, the velocity stacks are able to produce a ram effect which produces an increase in output, or conversely when the conditions are right a venturi effect which reduces power. These effects also seem to lend to some of the "hunting" the rotax's on the Lazair are known for.

I pondered over this situation for some time and thought I could correct this issue and maybe improve on the durability of the engines as they have always been unfiltered in the stock configuration. "To the Batcave" for some tinkering.

I found these really nice bell-mouthed velocity stacks used for a myriad of purposes, and some pretty little compact saucer shaped air filters from Chinatown, made by Chinamen, of ChinaQuality. After modification and sufficient fitting and futzing around the filter system is installed and looks quite good I think.

Flight tests show no degradation to performance, i.e. I get the same RPM as before, the engines run at a more consistent RPM and have less "hunt", and throttle response is unchanged. Overall I feel this is a good and warranted modification, it keeps the bugs out in the air and on the ground, and can only add to the life of the little Rotax. Kits are available

I hate to make promises, particularly ones I am not sure I can keep. While at Oshkosh this year I promised myself I would have the Mark IV ready to unveil for the 2015 show. I am doing my level best to meet this self imposed promise, but there are many factors out of my control. Still I think having a goal is a motivation in, and of itself, and will only help get me off my can and moving forward. Wing construction is still moving ahead. I am fitting the ribs to the spars, I need to build the wing jigs so I can set the washout per the build manual and make the new root ribs.

More Next Time,

Sunday, May 18, 2014

Baby Got New Shoes

A Clean Desk (Shop) is a sign of a sick mind.
Albert Einstein…..Supposedly.

Posting time again, I love it when a plan comes together. I have been toiling away like a little bee. I got a 6” carbon fiber spinner in the other day directly from China, made by Chinamen, in Chinatown, actually a really nice piece of work. The purpose of the spinner is to allow me to start the Evolution radials easier using an external starter and without endangering my hands and fingers. After adding necessary bracketry inside the spinner it has been fitted to the engine and works quite well. 

See the latest video of running the second engine using the external electric starter here:

I have also installed the 8” wheels onto the Lazair. These are the same wheels from the last blog. I had custom axles machined; these wheels are fitted with the Black Max Brakes as before. So now I have two wheels and brake options. You can have 6” wheels with black max brakes like those shown in the previous posts. Or you can have these snazzy new 8” wheels, which are the same size as the Original Lazair wheels, with Black Max brakes, as seen here.

I have two sets of 6” wheels available for anyone wanting to replace their broken original plastic Lazair wheels. These sets are wheels only, no brakes, if you want new wheels, and/or brakes, contact me and I can set you up with a wheels only kit or a full up wheels and brake kit of your choice.

Mark IV wing construction begins in earnest. Here are some pictures of the first rib being fitted to the Mark IV wing spar. This is very exciting!

A Newly Minted Lazair pilot.
Here is a video of my good friend Swaid flying my Lazair for the first time. He is a very skilled multi-engine pilot and I have every confidence in his abilities, but it’s always a bit nerve racking to let someone else fly your bird. He is now our officially unofficial factory test/check-out/demonstration pilot and hopefully will be able to accompany us to Oshkosh next year to unveil the Mark IV.

Service Difficulty Report

During a recent preflight inspection the upper aft seat tube support (G307) was found to be severely cracked. Upon removal it was found the bracket was completely broken. A magnified inspection of the crack surface indicated a crack occurred during manufacture, or as a result of manufacture, and propagated to failure via fatigue. Closely inspect your aircraft for this problem. A redesigned, stronger bracket is available and shown installed.

More Next Time,

Wednesday, March 19, 2014


"Big Things Have Small Beginnings."

  David, the robot.

I have not posted in a while. Many mundane (small) things are going on in the background, none of which are noteworthy in, and of themselves. So in the meantime, and for your entertainment, I posted a PowerPoint movie of a presentation I had the privilege to present to a local EAA chapter on the history and technical aspects of the Lazair (see previous post). I have also posted an instructional video on how to build Mark IV ribs. This video was developed to test the feasibility of using video media for construction rather than a written manual. It seems it might workout well, we'll see how the public responds before making a final decision on this format.

Mark IV Updates

We have finished the break-in runs on the first Evolution 7260 radial engine with 2 blade 32x12 Valley View prop. Everything is running as expected. The second engine is being fitted to the test stand for break-in now.

Below are current pictures of an aileron assembly with end caps, but no trailing edges. The covering material is Oracal. This is the same material used for graphic wrap on cars and boats. It is beautiful material, very easy to apply. But it does not shrink wrap tightly enough for use on the wing and it is too compliant, meaning it stretches too much. It is therefore not an acceptable candidate for a covering material by itself. However several ultralight manufacturers are laminating Oracal over Ceconite, Stits, Dacron, etc as an alternative to painting. This seems to work very well indeed, and so this system will be offered as a covering choice for anyone who may want a Lazair without the traditional see-thru covering. The Oracal will give a plethora of color and graphics options.



I have also finished the development work on the Black Max Brakes. These pictures show the new wheel and tire assembly. These are the same size as the original wheels, but use the Black Max master cylinders and calipers from the previous post. New axles are being machined right now and I will post pictures of the new wheels installed. We now have complete refit kits available for Lazair owners that want to replace those old cracked original wheels and/or want to upgrade to better brakes. Two wheel options are available, the 8" wheel you see below, and the 6" wheel in the previous post.
If anyone wants just wheels with no brakes I have 2 sets of 6" wheels available with axles for a very good price.

On a safety note:

I was committing an act of minimally regulated aviation by flying my Lazair a few days ago, and after landing and standing around chewing the cud with a fellow aviator friend of mine he made a safety suggestion that left me gobsmacked that it was so spectacularly obvious and that I hadn't thought of it myself.

He relayed a story of a friend of his who had an ultralight (not a Lazair) with a different engine (2 stroke, 2 cylinder by the same manufacturer as ours) that was installed with the cylinders upside down, i.e. the spark plugs pointed down instead of up with similar plug caps. He informed his friend he might want to safety wire his spark plug caps so they wouldn't fall off or wiggle loose. The friend dismissed the notion and subsequently destroyed his plane and nearly killed himself when a spark plug wire came off in flight causing partial power loss of the engine.

Now I have never heard of a Rotax 185 loosing a spark plug wire in flight. But after examining my plug caps (rubber screw on type with spring loaded clips) and taking into consideration the massive vibration these engines produce I thought his suggestion had enough merit and there was enough potential for failure of the cap to remain on the spark plug I got out my safety wire and devised a simple safety wrap on the plug cap that I am convinced the cap cannot come off until I cut the safety wrap.

I recommend all Lazair operators heed the same warning and safety wrap your plug caps to the spark plugs. It is very easy to do, costs nothing, takes only a minute or two, and is cheap insurance against this type of bad juju.

More Next Time,