Gap seals can aid in reducing not only drag and interference but flutter as well. Radim Horky is using them on his Arcus models and they are a useful and aesthetic replacement for wipers. Too, they emulate the seals on full-size sailplanes when done correctly.
Most moldies are lived-hinged so there is really no need on the hinge side from a performance standpoint. If your model has no wipers on the opposing side, a gap seal may be very effective. There is no problem with adding them to both sides for that special scale embellishment. I use them on both sides on knuckle-hinged models.
There are any number of ways to achieve effective seals. There are ready-made gap seal tapes available that will do the trick. Getting that scale look requires a bit more work so it might be interesting to see what options are out there. If you have sources for materials and/or techniques, chime in and share.
I'll start first.
Most full-scale(FS) sailplanes use pre-curved Mylar material and range in width from 22mm- 78mm with 35mm being a pretty common size on most modern glass ships depending on which surface it is and whether it is on the top or bottom.
The 35mm size works well for my purposes on most models and this size translates to about 7/16" wide at 1/3 scale. I use matte polyester (mylar) film in .005"-.007" thickness and cut it to the widths I need as I'll explain. I bought a 200 foot roll of .005" material from Grafix Plastics many years ago and have plenty...Continue Reading
I've had several people ask me about towlines for aerotowing in the last few months. There are several threads here on RC Groups and RC Aerotowing about them but no real details so I put the following drawing together along with some sources. It hopefully makes it easier to describe the components.
This is by no means meant to be definitive and I welcome your thoughts, experiences or insights.
I had been looking for a new, big, scale tug for a while and had considered several options. I was concerned about cost, size, ease of assembly at the field, airfoil, quality, etc, etc. Most everything winds up with compromises and my decision to go with the Hempel 38% Decathlon was no different. I found this airplane by chance after talking with Steve Rojecki at the JR Aerotow in 2009. He mentioned the Hempel 50% Cub and remarked he thought it was a pretty good quality offering at a very reasonable price. I went to Hempel’s website, looked at what was available and decided nothing there would fit my requirements. I wanted a tug with at least a semi-symmetrical airfoil, not too much area, and something that would accept a 150cc engine. Hempel didn’t have anything at the time that fit these criteria but there were rumors….
I kept visiting Hempel’s site and learned that new 38% and 57% Decathlons were in the works and would be available in early 2010. The 57% was off the chain for me but the 38% looked very interesting. I lurked around the giant scale airframes thread over at Flying Giants and learned a lot about Hempel’s planes. They were held in high regard for quality, flight characteristics and overall value. I asked a few questions which were promptly answered and a check for the cost of a 38% Decathlon was on the way to Tucson.
I received the plane a few weeks later. It was carefully packed and doubled boxed. Initial inspection proved most everyone’s observations...Continue Reading