OK, I will never tell a short story when a LONG story will do.
but please bear with me:
Back in the early 1960's my Dad and brothers joined the famous Strathmoor Model Club in Detroit. By then all the legendary stunt flyers and I-Beam builders had left, so we never rubbed shoulders with Daly, Palowski, the Ebejers, etc. My brother Arch built an Ambroid Ares (ugh!), and later Rick Sawicki taught him how to design & build an I-beam from scratch. Arch built a couple, then we moved on to sheeted/sparless wings. Other I-beamers in the area included Fred & Rick Bachl, and (sometimes) LeRoy Gunther. Of course we saw Billy Werwage and the big Ares most weekends at contests. Jerry Worth, & Gerry Phelps were flying beamers then back then too. We saw Steve Wooley's Argus, and Steve finished the Cobra in my Dad's basement one summer. Of course a BUNCH of I-beams were coming out of Indy too - Jack Sheeks, Jim Vornholt, John Davis and others. Later we met Rod Pharis, and much later we got to know Rollie MacDonald when he came back in the early 1970's - he and son Bob returned to I-Beams in the mid to late 1970's. Of course, Billy W was ALWAYS there with a whole array of I-beams along the way! After much trepidation I finally built an I-Beam, the Sheeks "Swinger", a little over a year ago, and found it was fun - wanted to try one of my own some day - enter the Mythbuster
* Most everyone flying an electric bird has basically taken a bird designed for IC and swapped powerplants. No harm there, but it seems that there is a level of optimisation left on the table. Thus this is my first ground up attempt at a electric design; by that I mean it has elements that tilted toward electric power that I would find unacceptable in a IC powered bird.
* Aerodynamically it was logical to continue the design evolution from where I left it with the Eclipse series. Starting with that efficient airframe would be great for electric, advancing the aerodynamics should help reduce power requirement, and result in much less wasted power thrown over the side. Drag removed from the airframe would be handed over to the Phoenix speed controller with its excellent governor to control potential wind-up.
* Among other things with electrics the traditional chin scoop is not necessary and it is ineffective. From a cooling perspective something like a radial cowl makes a lot more sense. Another bonus; with a radial cowl the spinner now becomes optional, and keeping excess mass off the motor shaft seems like a good idea, electric or IC powered!
Let's tie a bow on this: I made a few sketches to reconcile and meld the Classic I-Beam forms and radial cowl all around the aerodynamic forms I needed, then blend it all into something I liked. I wanted a retro look but still make it look contemporary. One early sketch I called "Miss Strathmoor" portrayed what a modern Strathmoor I-Beam "racer" might look like. A mix of straight line and curved line elements added some "vintage" (think DeHaviland or Supermarine S-6B) Swept tips and tail adds some "speed" to the look, as well as makes them look a little more modern. The I-Beam wing, stringered fuselage, & large wheelpants over large wheels all added some "attitude". Quite honestly, my sketch showed a conventional tail, the V-tail was a late addition. It was consistent with the slippery look and also provides that last bit of signature - less anyone question WHO's airplane this is! At 63" tip to tip and 47" nose to tail, it is among the largest birds out there. At 44 oz it is also among the lightest - Sparky should like that!
Initial flight tests have been very promising. RPM settings have resulted in faster than predicted lap times, hinting the low drag goal has been achieved and that we will have to update the RPM spread sheets for efficient airframes. Inside of the first 5 laps I felt comfortable with it, very groovy, but as expected due to high AR and V-tail, there is corner to burn; yet it modulates very well too. It also carries energy well through a corner. This all means that I gotta mess with the base RPM setting, then will fine tune the Governor gain.
Oh yeah, gotta practice some too..!
So, whatcha think?
Topic: Mythbuster! My first true electric design (Read 15357 times)