Howdy folks,
Some may have noticed that I haven't posted any build stuff for a while here, but I
have been doing some off-and-on building this past summer and fall. I've been "flying under the radar" on the current project though because just for fun I've been keeping it a secret from the planes original designer and club flying buddy, Keith Sandberg. I actually started work on it in mid May, but I've kept it on the lowdown until I could get it far enough along for a suprise "reveal" of the model at one of our Minneapolis "Piston Popper" club meetings. That "reveal" has now happened, at our club meeting last Thursday night December 6th.
Keith penciled out his .15 size "Challenger" with the idea of a good flying smaller stunt trainer/sport plane roughly 10-12 years ago as a totally original design. There are many details about it in my earlier Challenger .15 build posts here on the forum.
http://stunthanger.com/smf/index.php?topic=25177.0 The "Challenger .15" design is an
excellent performer, by far the best .15 size model I've ever held the handle on. Between Keith, myself and a few others, many have been built and flown.
The "Challenger .15" design has proven to be a good enough performer that for the past 4-5 years or so Keith has threatened to scale it up into a .40 size version, possibly even adding flaps. He has yet to fully attack the project, but this idea could easily end up being a serious Profile competition design. As a bonus, it's also a relatively simple build.
After finally getting my own .15 size Challenger finished and flying this past spring, I immediately wanted a .40 size one too. That's when I had the idea of "Just Doing It" and by doing so suprising Keith with the model that he hadn't quite gotten around to building yet.
"TOP SECRET" PROJECT BEGINS-MAY 2012... My "Challenger .15" was built using the rib set and plans available from Walter Umland. Because of that project I knew Walter had the design sitting in his computer. In early May I made a phone call to Walter to see how tough it would be to scale it up to a 50" wingspan and also get a 3/32" rib set cut. Turns out it wasn't too bad, I received the ribs and full size plans in the mail just a few days after that phone call. The "plans" at this point were simply enlarged/unedited prints of the .15 version, but it was all I needed to get going on a build, giving me my desired enlarged parts patterns. With the enlargement, the wing area landed on a nice round number of 575 square inches, hence my naming this larger version the "Challenger 575".
Still needing and using a bit of willpower here and there throughout this build, I'm now in the final stages of building an exact replica, bigger "Challenger". I've worked diligently at sticking to my original idea of keeping it simple and the only dimensional change I've made from simply scaling it up to a 50" wingspan is the addition of 1/2" chord to the full span of the horizontal stab. I had no real reason for this other than I thought it looked slightly better. All other dimensions and outlines are based on the original .15 design.
With this version being a .40 size model however, I did add adjustable leadouts and a tip weight box. I also did carved and hollowed L/E wingtip blocks and changed the tip rib layout slightly, again solely for cosmetic reasons. It took a fair amount of willpower to do this bigger one without flaps, but that's how
I'd envisioned doing this larger version from day one. I wanted to stick to doing it flapless just to see how well it will actually work out at this size. The rudder is fixed with about 1/4" offset, the aluminum L/G is stock Sig "Fazer".
Power on the "575" will be a Saito .40 and I'm planning to also duplicate the white/orange NAVY paint scheme as shown here on my .15 size version.
For those interested, build photos can be found here:
http://stunthanger.com/smf/index.php?topic=29511.msg286568#msg286568 Think spring!
Topic: "Challenger 575" (Read 1345 times)