The Prop is Balanced .. And the Tug is Online (almost)! What a Difference!

I Love my Glastar. Everyone I talk to about the airplane knows that. We're in the tweaking stage of new ownership of an experimental airplane. Among the early projects were items that I expected of a machine that was stored for more than 10 years ... tires, battery, wheel bearings, an oil and filter change. Items yet to be addressed include replacement of seals and O rings that dried out during the storage as well as updates for avionics, including ADS-B and backup instruments. The list is not particularly long, nor is it particularly short; storage is just not kind to airplanes, whether in a museum or in a hangar in northern Indiana.

One item high on my list for tweaking was the prop balance. Glastars, particularly those pulled by Lycoming engines on dynafocal mounts, have been known to develop cracks in their exhaust systems from engine vibration. Probably any airplane type similarly equipped should be watched by their owner, but I noticed in the web resources provided by the Glasair Owners Association that Glastars were singled out. My local CFI friend who gave me my initial insurance checkout mentioned an unusual amount of vibration and recommended I have it looked at by an experienced balance specialist, so I did.

There are 2 story lines that will eventually come up in this post: the prop balance and a new tug that Mark designed and built for me.

Look at the engine and you'll see a yellow laser gizmo that focuses on a tape that's applied to the back of the #1 prop blade. The blue tape indexes a protractor.

As best I can describe it, the prop goes round and round and the laser blips and a motion sensor/accelerometer records how far out of whack the balance is. The info is fed into a handheld device that tells us what's wrong and what needs to be done. Weights are then added to the spinner or the starter ring gear at computed angles to counter the out of whack-ness and things get smooth. What else is there to know?

Thanks to friend Dick who did the balancing job. It really made a difference.

Now for the tug. We started with Mark's tug, which he designed and built and has been in use for almost 2 years. A second one, redesigned, is in the works:

Mark is a mechanical engineer and a retired one at that who has time to think about things and how to make them better. In his mental perambulations, he happened upon the idea that a worm gear drive might fit what we were trying to build, so he did a lot of research and somehow came across a fellow who had a garden implement - a rototiller - with a worm drive of substantial construction and that lit a light bulb. The rototiller had a broken whatzit but the worm gear transmission was the thing, so Mark bought it. After a couple of fits and starts, we learned that the worm drive is meant to go one way only -- when we tried to run it in reverse, the worm drive disengaged. Back to the drawing board.

Rototillers take a beating in their intended use - for our purposes the transmission would have been on permanent holiday, but it didn't work.

Darwin provided the needed welding to make the whole thing come together.

The dadgum thing looked great, but looks aren't everything. 

The early beta test illustrated a huge benefit: it was a lot easier to pull my smooth running Glastar out of the hangar and put it back in.

No fear. Inquiring minds are on the job. One suggestion was to just go out and buy a tug that is in production, but what's the fun in that?