AirVenture 2012

I made it to Oshkosh again this year and as always enjoyed the few days I was there. It's fun making the long cross country flight and the Sportsman is a great plane for the trip. The weather was broken at around 1200 feet at Islip so I filed IFR to get out and was VFR within 20 minutes heading west. As usual I made one stop in Pennsylvania and another in Indiana before making my final stop in Watertown, Wisconsin.  There was some weather in the area but things were slowly improving as the day wore on.

Each year when I plan my trip I try to make it with the Glastar Sportsman owners who organize a mass fly in on the Sunday before the show starts. It's great fun and we leave early in the morning to avoid the rush. The other benefit of Sunday is that there is no air show that closes the airport, something that happens each day during the week of the show. I wasn't able to meet up with them this year but did take advantage arriving Sunday only later in the day. Here's my arrival:

For the first time I arrived on runway 27 which was fun.  Except for the Skyhawk who cut right in front of me then took it out over the gravel pit, which was a no no, I had no issues flying in (a lot different the last year!) I had a slight over shoot on my turn to final but made a pretty good landing.  I was thrilled to be there again!

I did have one surprise that I wasn't counting on. When some rain came through a day or two later and I decided to put my cover on and noticed a problem with my exhaust mount. One of the wires that secure the tuned exhaust under the cowl had failed.

 I don't know when it happened but I knew I couldn't leave until I got it fixed. Well, I had no tools or parts but heck, I was at EAA AirVenture! Turns out that EAA has is a group of Volunteers who have been staffing an emergency aircraft repair barn for a number of years. EAA has a great video of the people who run the booth. The people there were just great. The had the wire and crimping tool to make a new part and within a few hours it was good as new. Thanks EAA!

AirVenture was HOT this year. The midwest was in the mist of a drought and the grounds were dry and scorching! Thank God for having a high wing aircraft!

So this year was the 75th anniversary of the Piper Cub and there were about 75 cubs that flew in. It was a great sight seeing mostly yellow cubs all parked in the same spot. The first RV was also restored and did a fly buy. There was as usual so many planes to see. Here's a sampling of the planes I enjoyed the most.

75th Anniversary Cubs

Van's RV-1 

There was one plane that I saw this year which meant a great deal to me. I graduated from the University of Michigan in 1980 with a degree in Aerospace Engineering and I was fortunate enough to take an aircraft design course from Professor Edgar J. Lesher, a hall of fame designer and builder who held quite a few FAI records in the C-1a class. It was a privilege to take the class from such an esteemed professor and I remember seeing pictures of his Lesher "Teal" at the University. So imagine may delight when I saw his plane being displayed with other historic homebuilts. I couldn't believe the plane from my professor was right there in front of me. I'm sure most people just walked by it but for me, that was some special plane. Sure brought back lots of memories.

Always enjoy AirVenture, even as hot as it was.

Tailwheel Shimmy

So anyone who owns or flies a tailwheel aircraft will at some point run across the annoying tailwheel shimmy. I have never run into a pilot who hasn't had that dreaded vibration that occurs during landings. Whenever I meet an owner with a conventional gear I always ask how often he gets the shimmy and what he has done to prevent them from happening. The Sportsman is no exception.

When I converted my plane to a tailwheel, I was still an inexperienced tailwheel pilot but never had any real issue with the tailwheel. But the more I flew, the more I would get the shimmy occurring. I used to think that the real issue was the pilot and not the plane and that certainly has a lot to do with it. But the more I read about the issue in the Glasair Owners Forum, the more I learned about the issues causing that awful feeling on landing

The most important thing to get right is the angle of the tailwheel. I have the Alaskan Bushwheel on my plane and they have a short video that shows the proper set up for the tailwheel. The tailwheel spring tension and angle is critical for getting the best performance out of the tailwheel. Some of the Sportsman/Glastar owners were not happy with the original tailwheel kit from Glasair . The issue was the leaf spring. The feeling was the spring was not set for the proper angle and no matter what they tried, they couldn't get ride of the annoying shimmy.

Glasair looked for a solution and came out with a different leaf spring to try and help minimize the shimmy. The angle is different and it's beefier. I had the original spring so I ordered the new one hoping it would make a difference. Here's my original spring:

Now let me again say there are a lot of things that cause a shimmy. There's the tire pressure, which has to be correct ( I keep mine around 60 psi) and your gross weight. If your tire pressure is low, forget it. And you really have to measure it because just looking at the tire won't do. You especially have to be careful when it's cold outside and the air contracts.

Your gross weight and CG location also will determine if you get a shimmy. A high gross weight and an aft CG will also contribute to a shimmy. Now I don't fly a full gross very often but when I do I try to keep my CG as close to center as I can.

So here's my set up after the new spring.

Not sure if you can tell but the angle is better and the end result is a LOT less shimmy. Now I still get an occasional shimmy with either a crappy landing or some stiff cross winds but in general I'm very happy with the results. Some owners say the angle causes more lateral motion in the spring and I tend to agree but I still think it's a better set up than my original.

I have to say that in a conventional geared aircraft, the tailwheel is really critical. It has to provide all the lateral stability at touchdown and does come under a lot of stress. Now maybe because I land on hard runways all the time or maybe my landings are not always picture perfect  but my tailwheel tread wears out quickly. If I get a year out on the tire I'm happy. I never concerned myself with the tire when the training wheel was in the front :)

And one more thing, if you really want to avoid the shimmy, just do a wheely landing and avoid the situation all together.