Thanks, Crist!
Just a note about the carbon covered foam, its strength and rationale for making wings in this manner. I covered (no pun intended...) some of this earlier, but it needs repeating and perhaps clarifying.
The genesis (you just knew I'd get that word in here somewhere...) of this idea goes back to the days when I was the Contest Director of the Brodak Fly-In. We were adding Slow Combat to the contest menu and I needed an event director. I called my very good and long-time friend, Phil Cartier and asked him if he would serve in that capacity. He agreed, but with one big stipulation; I had to enter and fly in the slow Combat event! I told him that I didn't have any combat planes and hadn't flown in Combat since the 1960s (well, except for one flight at a meet somewhere in the 1970s). Actually I started my competition career in Combat and even flew in the Junior division at the 1961 Nats in Willow Grove.
Phil said not to worry; he'd lend me a plane, engine and arrange for a pit crew. He told me all I had to do was go as far as I could in the contest until I was eliminated and he'd be happy. Okay, that sounded fair to me. Little did I know that he planned (now, he will deny all this, but you be the judge...) to set up the "stunt kid" to be knocked around by some of the very best Combat fliers in the area, starting with our now departed good friend Gil Reedy, and followed by Bub Reece and the man himself, Phil Cartier. Hey, it was all in good fun. At least it was for me; at the end of the contest I gave Phil back his plane and engine, thanked him for the loan, and then collected my first place trophy in Slow Combat! I had won every match!
Well, naturally Phil, Bub and Gil had some well-deserved egg on their faces, but we all got a good laugh out of it. The problem was, Phil had lit an old fire and now I wanted to fly Slow Combat
and Stunt competitively! I started calling Phil almost every day with questions about how to get started with the best equipment. He suggested building one of his Gotcha series Slow Combat models. Being a foam cutter myself, I opted to work from plans and make my own fleet of planes. Phil schooled me about the construction techniques required to make a foam wing model without any sheeting. The basswood spars with shear web technique all came from Phil. He advised me to also use his plastic film covering material over the wing (I forgot the name of that material...). I fully understood the practicality of using that material, but to be truthful, I really didn't like the look of it. Yeah, my aesthetic sensibilities from years of building Stunt models kicked in.
At that point the Stunt world had discovered the .2 oz/Sq. Yd. carbon mat material, and we were attaching it to the balsa airframes using Nitrate dope. I liked the way the Stunt models looked covered with the carbon before the painting process started. I reasoned that the carbon could be attached to the raw foam wing cores using water thinned Titebond, and quickly did a test panel using that method. It worked so well, added so little weight, and imparted so much strength that I went ahead and used it on my first Slow Combat model, which, by the way I named "Slip Knot," after the Grateful Dead song of the same name. Hey, I'm a huge Jerry Garcia fan...
There was a Slow Combat event scheduled for the next weekend at Middlesex, NJ, and Phil, Gil, and Bub said that they would stop by (my house was on the way to the contest) and pick me up. I kind of felt like the "rookie" member of their Combat team at that point. They arrived at my house early in the morning and walked into my shop. I had my new carbon covered model all ready to go. I had built it like a small Stunt model; everything was carefully fitted, sanded and finished, and I even had made up a "Slip Knot" logo to go on the wing! It looked like a competition profile stunt model! I'll never forget what Phil said when he first saw that model; "You are going to fly
that in Combat? It's too good looking!"
That model flew very well; albeit for a very short time. I got mid-aired during my first match with the Slip Knot. But, I did get to have a few practice flights with it before the destruction began. Suddenly my bubble had burst; I wasn't going to repeat my performance at the Brodak meet... I probably should have quit while I was ahead.
I did finish a second Slip Knot and took it out to a practice session with Phil, Bub and Gil at their field near Hershey, PA. Phil took a flight on that model and told me that it was about the best flying Slow Combat model he'd ever flown. That just amazed me.
Well, as you probably guessed, my Slow Combat career never really got off the ground (so to speak...). But, a few years later the lessons learned from building those models would pay some dividends. My good buddy, Mark Weiss called and asked me if I would like to come down to South Carolina and help out with the CL portion of the Joe Nall Fly-In. Mark and his crew had been teaching people to fly control line using the Ringrat models that are manufactured by Stevens Aero. They did the job of basic flight training perfectly, and proved to be so rugged that they have survived that duty for many years now.
Mark had the idea to have a more advanced model available at the "Nall" for those who had graduated from the Ringrat and were ready for some aerobatic training. I volunteered (was volunteered...?) to design and build five simple profile models for that year's upcoming Fly-In. Trouble was, it was only a couple of weeks away! That's when Dean Pappas and I brainstormed the Joe Nall Cadet. It was designed to look a bit like the Yak full-scale aerobatic design that had a big radial engine. Hey, that look was the vogue at that time.
I enlisted an all-star team to help make parts for the Joe Nall Cadet, including Ken Armish, Tom Hampshire. Frank Imbriaco, Mark Weiss and Buddy Wieder. I took on the chore of making the foam wings and the foam core/balsa sheeted fuselages for that model and it hit me that the carbon mat method used on the Slip Knot would be the perfect way to expedite these models. I have no idea how we did it, but on the day Ken Armish and I were scheduled to leave for the Fly-In, there were five ready to fly Cadets to put in Ken's trailer. I must at this point give some credit to my good friend, Warren Walker, who used his amazing metal working skills to produce the custom dural landing gear legs for those models in record time. Some things are just meant to be.
I reasoned when getting ready to cover the wings for the Joe Nall Cadets that only the leading edge and trailing edge areas really needed to be covered. The strength in those wing came from the basswood spars and the shear webs between them. And, those models flew very well They were full pattern capable and impressed a lot of people with their performance at the Fly-In.
Around that same time Buddy Wieder and I had built the big test bed twin that was pictured earlier in this thread. Again we covered the leading edge and the trailing edge areas - and the flaps - with the carbon mat. The test bed twin flew very well, but Dean Pappas suggested that it might fly even better with the entire wing covered with the carbon mat. And so we did that, and he was right; it flew a bit better! We then retrocovered (new word?) some of the surviving Joe Nall Cadets in that manner and they too flew better.
I did one more model using the carbon mat/Titebond glue method recently. It is the E-Bug Lite, a profile electric version of Bob Baron's Humbug with some updated aesthetics to make it look more jet-like. See photos below.
So, when it was decided to design a simple to build, inexpensive electric twin, the carbon mat/Titebond glue method just made sense. Of course, if someone wanted to build this model with a balsa covered foam wing, it would work just as well, and I will supply that type of wing for this design in the future, as well as the Lost-Sheeting cores. Let's get it finished and test flown first...
Okay, that is a bit of backstory on this technique, and some history of the models on which it was used (thank you Sheldon...).
Later - Bob