Thread: Discussion 38% Bill Hempel Decathlon
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Old Mar 27, 2010, 01:24 PM
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38% Bill Hempel Decathlon

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 Hempelís 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 didnít have anything at the time that fit these criteria but there were rumorsÖ.

I kept visiting Hempelís 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 Hempelís 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 everyoneís observations to be correct. A great covering job, immaculate glass and paint work and a complete hardware package including some really spiffy wheels were evident. I carefully unwrapped all the components and placed them on benches in my shop. I commandeered the dinning room table for the wings. There just wasnít enough room in the shop to accommodate the 72Ē long by 24-1/2Ē wide wings without standing them on end in front of my wifeís car and that just didnít seem to be the safe bet. She made me promise to move them out as soon as possible, which, I pointed out, would require a lot of time spent in the shop in order to finish the plane within her time frame.

I evaluated the plane for about a week determining the assembly sequence, tow release position and installation, position of fasteners and construction and just generally becoming familiar with it. There are no instructions with the model, just tiny slips of paper with writings in Mandarin and English in each hardware bag denoting the assembly to which they belong. That helps quite a bit. It seems the accepted theory is if youíre ready to fly such a beast, youíll be able to figure out how to put it together. I also got some good insights by visiting a couple of build threads for Hempelís Cubs over at Flying Giants. Iím pretty much right-brained so the pictures included in those threads told me what I needed to know.

I like to make as many parts as possible removable on my models. Iím always looking ahead trying to anticipate recover jobs, repairs, general service, replacement of parts and transportation. I try to design assemblies and attachments to allow me to remove them for access, replacement and even initial finishing and covering. The Decathlon has removable stabs (one of my requirements) and of course wing panels. The gear isnít easily removable but Iím working on that one.

So what are the compromises at this point? The wing struts and empennage flying wires will be a bit tedious at the field, but not overly so. A DA 150 wonít quite fit in the cowl, it needs a hole for each sparkplug cap and wire. The new DA 120 would be perfect and Iím also looking at a BME 150 which should fit nicely with a bit more uummpphh for towing the ďfittycentersĒ. The structure is a tad lighter than Iím used to. Not a bad thing, just designed for the IMAC crowd; hovering and general cattawampusing. I hope to place this in the advantage column in the future.

Pluses include a symmetrical airfoil for reduced drag and increased speed, plenty of room for anything you might want to put in, good looks, pretty much built, high quality and a great overall value for what you get.
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Last edited by Asher Carmichael; Mar 31, 2010 at 09:52 PM.
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