ORIGINAL: themadmax
Some of the other items you'll have to change to bring the Vailly Birddog up to snuff are the landing gear. They look like football players legs on a ballerina. The Birddog has very elegant, slim legs, thank you. And the cowl...it ain't right. Your photos will tell you that. The full scale cowl only has a nose bowl. That's because the rest of the cowl is flat sheet, bent to shape. It's not like a 150 or 172 cowling at all.
And then there's the weight...unless you change you basic thought process from boatbuilding to airplane making...you'll always be building something that's heavy like a boat. In my book, 27 lbs. for a 8' wingspan aircraft is way over the limit for scale flying of this particular aircraft. As an officianado, (Which I appreciate you for), you know the Birddog is nothing short of spectacular in a high performance, STOL takeoff or landing. That's because it's a stressed skin airplane that weighs far less than any other Cessna with little cross section drag and lots of wing/power.
I'll look forward to the MAN build. The landing gear is another "compromise". Unless you want to have a custom made carbon fiber or spring steel landing gear, the chunkier aluminum is all that will stand up to any sort of decent life-span; I have considered it, but not beyond the initial thought that it might be a possibility. As far as the cowl goes, I have the fiberglass cowl sold by Vaillancourt, and except for the rounded front edge, there's not a compound curve anywhere on it. I was fairly impressed by the thickness and overall quality and scale fidelity. Of course, it doesn't have any "wavy" spots like all the full-scales I've seen, where "flat" just isn't, really; so I guess it's too good, especially for what I plan to build mine as, a Vietnam-era "Dog that's seen some action.
The span on the 1/4 scale is actually 9 feet (108 inches), and I fully expect mine to weigh in the 25 pound range. I'm putting a ZDZ-50NG in mine, to turn a scale 22" prop. Should fly fine, and with the flaps it has, STOL won't be any problem at that weight. I have an old Nosen trainer, very similar basic form, 96" wing and 22 pounds, with a US-41 and 20" prop on it. No flaps, but takeoff takes about 75 feet and it will climb at a 60 degree angle. I'm thinking my 'Dog will be at least that good, with another 20% wing area and 5 pounds heavier, but almost twice the power.
The full scale, depending on the model (A,B, or E) weighs a little more or a little less than a basic 170B, has the same wing and flaps; the gross weights are within a couple hundred pounds of each other, also dependent on model, and performance is also similar. So it isn't all that far ahead of some other GA craft, and the 170 will do it with 4 people in it. What gives the BirdDog more oomph is the extra 55 hp. Dang, I'm gettin' all pumped up to build this thing, all over again. Guess I'll have to clean up the shop[:@]