BykrDan

Hello;

I promised earlier to post a full build report of the GeeBee Z, so here it is:

The occaision for building this plane was upon tearing down a wall in our church building that had a thin, 1/8" panelling on it which made me think "this would make a neat airplane!"

The first order of business was to obtain plans. I didn't feel I had the talent or inclination to design my own airplane, so I went on the hunt for "free" plans. By "free" I mean "made available to the public at no charge", not "stolen." To my delight, I found a three-page set of GeeBee Z drawings by a Mr. A. Page in .ZIP format. Not only did I find the plans I was looking for, but if I'd had name a plane in particular that I wanted to build, that would have been the one! I happily downloaded these and printed them on 8.5x11" paper, nine pages (3 by 3) to a sheet and taped them all together! Sounds troublesome, I know, but the advantage to this approach is that I could scale the plane to the size I wanted, which turned out to be a 48" wing span.

The downside to this is that after I started building, I noticed Mr. Page (actually RCM) had a copyright on the plans. No problem, though. A couple e-mails back and forth to Mr. Page got things all straightened out and provided me with a legitimate copy, though I was already building from my own scaled-down version.

BykrDan

With plans out of the way, I began cutting wood. The "box" and former construction was fairly straightforward. I cut each side of the box out of a single piece of my "ply", and braced it across with 1/8" hardwood dowels. The fuse formers were then drawn onto the ply in two large pieces. (F1 and F2 were perfect circles - the rest, I printed off on a laser printer, cut out, and fastened them to the ply with double sided tape. This was before I discover 3M 77 spray adhesive!)

The stringer notches were drilled out with a 1/8" bit before sawing. I shaped each former on the scroll saw, passing the blade just through the outside of the holes for the stringers. This resulted in a nice notch that the stringers just popped into and stayed in place. Where possible, lightening holes were drilled in each former. In retrospect, I think I could have sawn a larger void out of each former in each side, and the top, leaving only the rectangle around the box and the circle around the fuse, and still had plenty of material, but at the time, I didn't realize how important it would be to shave weight down now.

With the box constructed, the inside of each fuse former was measured and made to custom-fit, rather than measuring from the plans, and not have something meet up in reality. The formers made a very good fit onto the box.

BykrDan

Next came the tail surfaces - again, rather than use balsa, or even my ply substitute for this application, I trotted down to Home Depot and bought a small piece of 1/4" ply. I think the plan called for solid balsa with ribs top and bottom (or maybe ribs, with a solid sheet top and bottom). I opted to cut the outline of each piece out of the ply, leaving a diagonal truss-work inside to brace the outline. This worked okay, although the ply was prone to warp before it was covered.

This part of the build was going on in the dead of winter. A couple times I tried to move operations to the basement, where the furnace was, but the effect on the woods was horrendous, and I was relegated back to the garage!

A little more forethough as to where the control horns would land would have been helpful (as it happened, I lucked out).

At this time, I was notching for my nylon hinges with an exacto knife. Later, I found that a dremel cutoff wheel chucked in the drill press was far superior to this. I moved the bench up to about 1/8" from the wheel, and then slid the part to be hinged up against the wheel. A few passes, and I had a nice semi-circular notch that would just accept a Dubro hinge.

In my zeal to try MonoKote and cover something, I forgot entirely to round the leading edge of the horizontal stabilizer! No matter - if it makes a difference in flight, I can't tell.

BykrDan

My stringers, as mentioned, were simply 1/8" hardwood dowels, again, from Home Depot! They snapped into the notches perfectly in most cases. About this time, thank goodness, I discovered CA! Up to this point, I'd been using carpenter's glue and 30 minute epoxy. CA sped up the work tremendously.

After the stringers, I started on the planking, where I finally broke down and bought some 1/16" balsa sheets. The planking was not nearly as bad as I thought planking would be - I rather got to enjoy it. I had a few gaps near the top of the plane, but by the time I worked around to the bottom, it was looking watertight, like a barrel. The only problem I ran into, and I'm still not sure how to do this right, was mating the planking smoothly where it butts to the stringers. Since the stringers project just a little up from the formers, I was cutting notches in my planking so it wouldn't ride up on the stringers. Even then, the planking was even a little higher than the stringers, which shows a bit through the covering.

I planked down as far as I could, and then I needed to know how the wings were going to shape up so I put the fuse on hold for a while.

BykrDan

The wings were a joy to assemble. I pinned enough rectangles of ply together with a pair of 1/8" dowel rods to make a complete set of ribs in one pass - the assembly just fit in the mouth of the scroll saw. The outline and spar notches were cut, then more lightening holes drilled though the whole stack (again, sawing voids may have saved more weight and still left plenty of material), and then finally sanded to shape. I used 1/4" hardwood spars for the top and bottom spar (I really had to hunt for straight ones at the hardware store). I took another, and placed in a jig, planed and sanded off one corner for the leading edge. One more spar, planed top and bottom for some taper, made the trailing edge. The spars fit well enough that the wing held its shape without glue. I cut the pieces of shear web out of ply and set them between the ribs. Using a flat surface, on wax paper, with the trailing edge resting on another straight spar and raised at the outer end to hold in my two-degree washout, I CA'd everything in place.

The dihedral braces were cut out of 1/4" ply and epoxied afore and aft the main spars. Wing bolt blocks were made of the same, and extended from the innermost rib, along the TE, and each met the other in the center of the wing. A 1/4" dowel projected through the center of the LE (drilled out ahead of time on the press) to the front dihedral brace.

The wings were sheeted with 1/4" balsa, windexed, and held in place with ACE bandages to adapt to the wing rib shape, left to dry, then removed, glued, and bandaged again for the final application.

Ailerons were made of solid strips of poplar, shaped with the plane and sandpaper, and drilled generously along the length with lightenening holes.

I did a little modification to the plans at the wingtips. To give the wings a more rounded appearance, I lengthened the tips by 1.5". Also, instead of webbing in a straight line from the top of the wing to the tip, each web was slightly rounded. It looked very nice on the finished wing. Regrettably, I did not understand at this time the importance of the filler material at the front and back of the tips. The fronts of the wingtips catch the brunt of bad takeoffs, so not only would they benefit from a little reinforcement here, but the covering has a pretty sunken look at the leading edge of the outermost rib. Next time, I'll know!

The belly pan under the wings was cut to shape, and ace bandaged to a football after dampening with Windex to introduce some of the compound curve needed. It worked reasonably well.

BykrDan

With the wing shape now determined, I cut my 1/8" poplar saddles to fit, and then I could continue planking down to the wings and beyond. I planked right down to the wing surface, in case I decided to scrap the fillets altogether (which I very nearly did). I got a little hung up in that area. Either I didn't read the plans correctly, or didn't understand them, but I saw no way how the various fillet formers and sheets given on the plan could possibly come together. Not to mention that they called for sheeting over a compound curve, which I wasn't ready to try yet! After staring at it for about a month, I re-drew the fillets with only slight modification, but brought them down lower on the fuse side and made it a simple curve. Plus, by drafting my own, I could determine a pretty precise shape for the fillet sheet. The sharply rounded font of each fillet was actually a thick rounded former made from 1/4" balsa.

BykrDan

With the fillets done, I could start covering. I sketched out the major shapes on graph paper, and then measured the plane to get dimensions. I wanted a very neat appearance, with as few seams as possible (I didn't realize at the time how barely noticable Monokote seams really are), so I created some pretty large sheets, starting at the bottom of the back. The entire bottom of the fuse was covered in two continuous pieces - front and back (not counting the seams where the color changes). Each side of the rudder fin was done in one piece, and a single piece went over the top and sides of the fuse dormer. The area in front of the cockpit was also done in one piece (except for the color change), which was the only area that gave me any trouble at all. The fuse top was just a little too round to get all the 'kote down without a small wrinkle on each side.

BykrDan

The canopy took several tries to get right, but the basic steps of the process were: create a wood plug in the desired shape; take a lead casting of it; fill in low spots with Bondo and sand it to a smooth finish; construct a jig to hold it inside a two-liter plastic bottle with the ends cut off, at a slightly nose-up attitude; and finally, bake it in the oven at 500 for ten minutes. I had to watch it closely - just after the plastic would pull down tight over the plug all the way around, it would burn (sometimes before). There was a short window of opportunity to get it out of the oven.

I made the final copy out of a green Mountain Dew bottle (which sets off the yellow very nicely, and somewhat obscures the unfinished cockpit.) After debating several methods of attachment, I settled on simply gluing it with epoxy, which has proven durable, and looks quite nice.

BykrDan

The landing gear was a simple matter of cold bending the right size music wire to shape, except the first pair was discarded, as I did not construct a jig to ensure I would get an identical pair. The second set turned out great. I used silver solder and a propane torch to join the two pieces of each leg.

BykrDan

Next, it was time to think about a power plant. I hung an empty pop can from the front of the firewall and dropped in lead wheel weights (free from the local auto repair place) to establish the weight I could spend on power. It turned out to be 850 grams to balance the plane (short nose), which drove the wing loading up to 26oz. After much debate (and help from the group), I settled on a brushless AXI 2820-10, on ten cells, with an 11x6 or x7 prop, which turned out to be the perfect choice, I think. I wanted long flight times, and so settled on a 2100 mAh battery. Cramming all of this equipment in the airframe would be a challenge!

To develop a lightweight, brushless motor mount that would hold the motor about 4" from the firewall, plus brace the battery, I used a PVC shower drain and pipe cap, with generous holes and voids drilled and sawn throughout. The pipe cap was held on using PVC cement, and sewn together with zip-ties through the lightening holes, for good measure.

BykrDan

I made a fiberglass cowl over a piece of tupperware and a large tin, both of which where filled out to the proper shape and size with Bondo. I used three plies of lightweight glass. I should probably have used a fourth, but weight was getting very critical here, and the cowl held its shape just fine once the mounting ring was fastened in place. I made one lengthwise cut to peel it off the plug.

BykrDan

Well, I must say, it's been an absolute joy! I had four great flights on it (with four average landings), which I posted earlier. Takeoff number five was kind of rough (the motor was a little draggy from landing number four), and some of the airframe was damaged. The damage has since been repaired, but I think I may retire this plane, and often reflect back with joy at the process of building and flying my first scratch plane!

I'm on the hunt for another project now (winter's just around the corner) so watch for future posts! I have a good idea what it's going to be, but I want to work some things out first.

Thanks for listening,
Dan.

andy120

any chance you can email a copy of the geebee plan, i cant find it anyplace on the net. i have the RCM issue adrians build up was in.

thanks
andy

BykrDan

Hi Andy;

I heartily recommend you contact Adrian for his plans. You can find him at

http://www.adrianpage.com/

And ask him just for the plans for the Gee Bee Z (they're not really listed as a product on the page by themselves). His current plans appear to be much more scale than the RCM subject.

Dan.

Baldeagle

My Feedback: (7)

Dan
Nice project, the plane looks super. I have the Page R Gee Bee nice flying plane. nose overs are quite common. Keep us posted on the next project.

BykrDan

Thank you Rich,

You're not kidding about the noseovers! I've yet to make a fully wheels-down landing. Happily, she repairs nicely.

I believe I read about your adventures with the "R". These planes are a joy to fly, if not land.

Right now I'm debating between another low-wing racer (maybe one that's not so scale, yet would be an easier build - the "Z" wore me out) and an F4B-4. I'm leaning toward the Boeing...

Dan.