Posted by Ken in reply to my questions:

David,

I don't mind the plan being posted. The original plan from the MB article appears several places in RC Universe.

Now on to your questions: Wow, you're asking me to remember back 31 years for details of a one-off building project. I'll give it my best shot.

- Yes it was square stock, but it had to be carved on the outside and hollowed on the inside to the contours shown in the fuselage cross sections on the plans. I spot glued them on initially, then carved and sanded the outside. I then popped them loose and carved and gouged the inside so that about a 1/8 to 5/32 wall thickness resulted. Then they were glued back on permanently. It was never an easy airplane to build in the balsa version. You can use triangle stock, but you'll have to extend the fuselage sides up to the top of the canopy rails and down to the bottom of the lower rails or you'll have nothing to glue the triangle stock to. As I recall, I contoured the fusealge and canopy separately and finally glued them together only after sanding. If you don't do that, it's very hard to carve and sand the concave discontinuity between the fuse side angle and the canopy side angle (See Section B on the plans).

- Yes, everything was contoured to fit the around the firewall shape shown (See Half Section A on the plans). I believe the firewall was glued to the flat fuselage sides first. Then the 3/4 square was shaped as described above and glued to the fuse sides and the firewall. Finally, the top block and bottom sheet were shaped and glued to the fuselage and firewall. You can put square or triangular notches in the firewall, but make sure you have plywood firewall wherever a motor mount bolt goes.

- I think I cut away the lower cross member of F4 to make room for the flap linkage.

-The flaps are a constant chord, but the wing is highly tapered. This makes the inboard end of each flap a smaller percentage of the local wing chord and the outboard end of each flap a larger percentage of the local chord. The result is the outboard end of the flap is thicker than the inboard end. The plans are correct - the deepest rib goes outboard.

- Our aileron well covers were Trim Monokote. The servos were mounted to a plywood floor in the well.

- The first Brushfire had a flying stab using a Giessendanner (sp?) mechanism. The nylon control arm that came with it didn't fit inside the narrow fuselage at that location. So we drilled a hole for a threaded rod control arm in the square aluminum bar that was the spar for the two stab halves. It worked great until the stab came off in flight and totaled the airplane. The aluminum bar broke right at the small hole we drilled. You're never so stupid as when you're being smart! I haven't been following the hobby as of the last 20 years and have no idea what kind of flying stab mechanisms are available these days. Can someone else help out here?

- Yes, we ran 11 or 11 1/2 inch props. The Brushfire was very solid on its gear. You should have no trouble lengthening it some as long as the wire diameter isn't too flimsy..

- Balsa Brushfires ranged from 8 1/4 to over 11 pounds. It all depended on how much hollowing you did, whether the wing was built up or foam, and if it was foam, whether or not you you included the lightening holes in the cores. Fiberglass versions with cut out foam wing cores could come in at less than 9 pounds. The span was 65 inches.

Good luck with your project. That engine and the size you've settled on should be a show stopper.

Ken <span class="info"> </span>