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Mod'd Hostetler 1/4 GeeBee R2

I have begun the redesign of the 1/4 Hostetler GeeBee R2. This is basically the test model for me, as I am making many changes to enhance its scale accuracy (over-all the only thing accurate about it, is the fuselage shape forward of the canopy, and the wing outline). Once the airframe proves to be accurate (through scale competition), I will use the modified plans to begin building a 50% version mimicking the full-scale's construction (that means welded steel tube fuse with wood bulkheads for the shape).

Anyways, for documentation, I started off with the following Books:

"GeeBee" By Delmar Benjamin and Steve Wolf
"Gee Bee The real story of the Granville brothers and their marvelous airplanes" By Henry Haffke

Plans are from Hostetler, but I also ordered the Henry Haffke 1/4 GeeBee R1 plans from AMA and the vern Clements 36" wingspan Gee-Bee R1 plans from AMA.

I purchased all the plans to see which ones "agreed" with the Benjamin R2. Hostetler's were the closest resemblance in most instances, but will need many modifications to make them accurate.

First mod needed is the wing:
The Plans as drawn use what appears to be a modified Clark-Y. The original had a Very thin and reflex'd "Naca M6 @ 65% thickness". Using Profilli 2 i'll be re-drawing the wing to incorporate this airfoil. This will increase the take-off and landing speeds, but is a necessity because the airfoil as drawn is nearly twice as thick!
The original wing also has a 3/8" bass-wood plug that is glued into the outer wing panels and goes all the way to the center of the fuselage (about 12"). Since the model will incorporate functional (and scale!) flying wires, these large "plugs" won't be needed. I'll probably just have them go into the center stub wing about 6". The reason for the elimination of the huge plugs, is they are no longer supporting the majority of the flight loads. With the addition of functional scale flying wires, they will transfer the flight loads to the fuselage instead of the plug spars.
The landing gear mounts will also need changing to accommodate the Sierra scale struts.

Fuselage Construction:
As drawn, the fuselage is built with a pair of light-ply sides that are "curved" to follow the outline of the side of the fuselage. I REALLY hate building "curved" fuselage parts b/c they are nearly impossible to get perfect on both sides causing big flight problems due to an inaccurate shape.
So to fix this issue, i'm going to build up a 1/4" sq Balsa/spruce structure similar to the welded tube fuselage of the full-scale. This will allow me to incorporate hardwood dowels in the cockpit areas so when looking inside the door (which will be functional) and the canopy, it will actually appear to be welded tube.

Landing Gear:
As drawn, the plans show the Byron P-51 Gear struts epoxied into a hardwood "block" in front of the leading edge. This block is pretty substantial (in weight), and the Byron struts are no longer available (and wouldn't work with the flying wires anyways).
I'll replace the giant hardwood block with some carbon/ply laminates. The functional flying wires will also attach to the gear struts and the wheel-pants will be 2 piece and the lower portion will split from the top half so it "floats" with the oleo action, again completely scale.

Control system:
I'm not even going to THINK about letting any control linkages be exposed on this model, it would just completely Ruin the looks of it! So all the control linkages will be completely concealed. For the fuselage and rudder, this is fairly simple. The problem comes with the wings.
Due to the thin nature of the wing, not many servo's are capable of fitting (the thin wing ones would, but i'm wanting some substantial torque for these ailerons). So to solve the problem,i'm going to replicate the full-scale design. I'll take some aluminum rods and drill 2 holes in it. These holes will be tapped for a 4-40 bolt and then this will slide into a brass tube epoxied into the aileron. The aluminum rod will be supported in 2 bearings in the outer wing panel and the rod will be cut in 1/2 along its length for about a 1/2". This will then slide into a brass tube into the stub-wing (which will also have a aluminum rod inside the tube cut in half lengthwise for about 1/2") and supported by a few bearings. the opposite end of the cut will be tapped for a 4-40 bolt and setup for a Push/pull linkage from the aileron servo. When the wing is slide into the spars, the 1/2 rods will engage each other which will provide a completely hidden aileron control linkage.
I know it sounds complicated, but this has been used on some full-scale airplanes and works great. Its easier to show than explain, so be patient for the build!

Horizontal Stab:
Its not even close to being accurate in outline. The span is to large, the root chord is to small, the LE sweep is to shallow, the elevators are the wrong shape.. Its just WRONG. So it will be completely re-designed. Oh, its also 1 1/2" to high on the fuselage, so this change will be incorporated as well.

Vertical Fin/Rudder:
The vertical fin is drawn with no offset. Thats not scale, so the off-set will be incorporated into my model. The Rudder LE shape is also to "fat" from the cockpit "rail" and above, so this will be re-done as well. The Vertical fin LE is also tapered to much and should be more rounded along the top. The Rudder side view shape is "close", but the point at the bottom is to rounded (and to large) and the curve along the top 1/2 of the TE is to gradual. Again, lots of mod's to the tail section. The turtledeck behind the canopy is also oddly shaped and not accurate.

Covering:
I'm not completely Sure how i am going to go about doing this. I've been thinking of using Stits Lite but not sure. The full-scale was completely covered in fabric except where metal panels were. Even the solid plywood sheeted wings and tail were fabric covered and sanded extremely smooth. I may skip this part and go with fiberglass since their won't be much of a difference at such small scale.
The Fuselage stringer area definitely has to be covered in fabric though. This poses a unique problem. Their is a mixture of fabric and sheet-metal panels on the fuselage. So i have to figure out how to replicate this without a "ridge" where the fabric and whatever else meets... Anyone used Stits lite? Got any suggestions?

As far as the particulars for the model, here we go:
Graphics will be from someone (probably just do paint masks and paint everything).
Power will be from a Seidel ST7-70 radial engine (the one off my FW-190). unless of course the engine sells, then it will be with the new Evolution 99cc radial
AR9000rx w/ a Powerbox switch and A123 rx battery
JR servo's

After going to three different places over 2 days, I finally found a place that was able to copy the plans for the geebee... unfortunately they had to cut them to fit their scanner... So the re-design and building can begin.

First up was changing the inner fuselage "structure". Hostetler has you build a pair of full-length fuselage sides from 1/8" balsa laminated with 1/64" ply on both sides. These are then "curved" and placed down the center of the fuselage and balsa spacers used to hold the curve.

I personally don't like that curve (you can see the "orange" on the top view of the fuse, this is the original outline), as it will make things a bit difficult to keep straight..

Attachment 2236611

So the inner fuse plate (for lack of a better term) will be built up from 1/4" sq. spruce, balsa and balsa sheet. I believe this will be just as strong and lighter than the as drawn setup. The pink outline on the top and side view.
Looking at the top view of the plan, the inner structure is parallel to the center-line from the firewall aft to the instrument panel. the sides then taper back to the last bulkhead.
The outer bulkhead templates were then modified so they fit the new fuselage plate. Their will be 1/4" sheet balsa in the area where the wing carry through spars pass through the fuselage. This can't be figured out until I have the new wing ribs drawn up.

http://img.photobucket.com/albums/v4...2/DSC03246.jpg

A quick photo of the landing gear. A quick phone-call to Darrell this morning and the tire issue was figured out and resolved, once he gets the smaller 5" tire in-stock he's going to send me those tires.

Attachment 2236612

Also while re-drawing the fuselage structure, the stab was checked and as drawn on the plans it is 1 1/2" to high on the fuselage, so the new position was drawn. I also started checking the dimensions and shape of the horizontal stab in relation to the 3-views I am using, and was appalled at how far off it was. The span is 4 1/2" larger than it should be, the LE sweep isn't steep enough, the root width is to narrow....
Over-all, the entire horizontal stab and elevators are going to be re-drawn.

Here's a photo of 1/2 of the stab and the 3-view showing how far off it is:
Attachment 2236613