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Dan Cooper's Slingshot Page KCooper@ptd.net 2/11/09 Update:

Last night I was up until midnight trying to rig my wings. My first attempt several nights ago ended in frustration. After leveling the wings spanwise and chordwise, leveling the fuselage (roll) using a plumb-bob and getting the proper pitch (which determines where the attach tabs end up), I could not get the wings symmetrical (from the trailing edge to the rear of the fuselage tube) and still fit loosely in the leading wing attach point. I know it's hard to picture, but I have four points to adjust, each at an odd angle and still achieve symmetry. One wing always wound up binding on the flanges. I was so depressed I couldn't even look at it for a couple of nights. Finally, remembering my Firestar building days, I grabbed a grinder and countoured the tabs to allow the wings to fit closer to the fuselage and problem was solved. All the measurements came together. I put the Prozac back in the medicine cabinet. When setting up for the rigging, I had the bright idea of putting the fuselage up on the bench which would put the wings at a height I could easily walk under. I wasn't thinking about having to drill (5/16") the flanges on top of the wings. Standing on the bench caused things to move and shift from my setup. I wound up with 2 feet between the wing flange and the ceiling. I envisioned all kinds of scaffolding, from the engine hoist with plywood attached to two step ladders with boards in between. I also envisioned falling on the plane and ruining 500 hours worth of work. While getting hay for the animals, I stumbled across my daughters wooden swing set in the barn. We tore it apart for the winter. Leaving the middle part out, I wound up with two legs and a nice ladder-like platform going across. It worked great, at the right height, sturdy, and didn't take forever to build. My neighbors must think I've went off the deep end. I drilled the holes but things still shifted a little. With some adjustments on the trailing edge connections, everything fell back in place. I went in the house and celebrated with a bowl of cereal.

Now with the wings attached at level, I have to put an inch of dihedral in at the outer rib, and build my wing struts. Once the wings are secure, I can temporarily put the flaperons on with the linkage and insure they are going to be functional. I have some concerns about the hinge placement. I better keep that Prozac bottle handy. I'll post some pictures later.

1/20/09 Update:

Sorry for the long pause between updates. It's warmed up to 10 degrees outside and I thought it was a good time to write about my progress.

We've actually come a long way since the last update. The tail feathers are covered in fabric and ready for the second coat of Poly brush. The fuselage is painted and is near sitting on it's own two wheels. I've kept it on the jig for covering and painting.

For those not familiar with the Stitts covering process, the fabric is attached loosely to the surface with Poly Tak or what acts and looks like rubber cement. Once all the edges are cemented, you iron the surface (with an ordinary iron) at a pre-calibrated 250 degrees. The fabric shrinks itself tight on your airplane. Another shrink at 350 degrees will finish the job. The fabric shrinks so tightly, that you have to keep a close eye on the structure's edges and stop when they begin to scallop. Now you can brush on the first coat of Poly Brush (the "dope" in Stitts). It's brushed to make sure the Poly enters the weave. Once dry, the fabric will act and sound like a drum. Next, its finishing tapes, inspection holes, fabric gussets and lots of touch-up with the iron. Next, another coat of Poly, sprayed this time for uniformity. Another spray coat and the Poly is done. Now we apply two coats (perpendicular spray patterns) of UV Block, a silvery paint to keep the sun from decaying the fabric. After a little light sanding, its time for the paint coats. One has to wonder how a plane flies with this much stuff on it. Its really quite light though, but very durable.

I have covered the bottom and the right side of the fuselage. I was holding off on the other side until I received my ELT which came in the mail today. While not a big fan of Ebay, I've saved at ton of money on instrumentation by carefully buying used. So far, so good. I have downloaded some pictures of the covering process. If anyone has any question, please feel free to email me. The biggest challenge now in the building process is keeping the shop warm.

I promise to be more timely on the updates. Stay posted.

3/15/08 Update:

This week we've completed all of the major fabrication including the floor pans and fuel tank support. The pilots seat has also been temporarily installed. Now, most inexperienced builders would attempt to sit in their fuselage, maybe make airplane noises, pretend they are skimming the treetops over the Grand Canyon forests... just a word of caution, don't sit so long that your legs go asleep, you can't get out when your wife calls you for dinner. I even tried the passenger seat. My visions of electrical panels and overhead instruments were squashed when I "squeezed" myself into the pilot seat. I don't remember my Firestar fitting like a glove, but I may have been somewhat less stout then.

So now it's clean, prime and paint. I spent 2 1/2 hours at the wire wheel cleaning up the metal parts that we pre-drilled last week. Scratch one bench grinder after overheating the bearings. Tonight I ordered a quart of Daytona White and a quart of Santa Fe Red that my wife picked out. I want the metal components White so cracks will be readily visible. The wings and horizontal stabilizer/elevator will be red for visibility. A simple paint scheme, major components with solid colors. No stripes, a promise I made to a friend a long time ago.

I included a picture of my shop buddy, who has endured some long build nights and reminds me when it's time to go in and go to bed.

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This page is designed to share some of the experiences of building a Kolb Slingshot through pictures taken during the building process.

I purchased the Slingshot Kit in 1997 from the original Kolb Aircraft after seeing it perform at Oshkosh '96. I had high hopes of a quick build that was put on hold several time due to moves, job changes, and remodeling projects. Thanks to the excitement of flight shared by club members, I'm determined more then ever to complete the project.

Typical build time for a Kolb is approximately 400 - 600 hours. I currently have a little over 250 hours total in the build. To say this has been a long slow build, would be an understatement. My build documentation alone spans 5 Operating systems, not including my notebook when a computer wasn't handy. Not long after I purchased the Slingshot, Homer Kolb sold Kolb Aircraft to The New Kolb Aircraft stationed in London Kentucky. With that sale, I lost nearly all build support. TNK was learning to build, support and design their own aircraft and had little time or interest in builders struggling with "Old" Kolb aircraft. Fortunately, "Old" Kolb's documentation is well written and illustrated.

One of the biggest stumbling blocks in my progress was my Inboard wing Ribs that are made of pre-welded chrome moly. The ribs have a tang that extends into the wing spar for additional support. On my kit, the ribs were inadvertently welded with the tang on the wrong side. Dennis Souder called me shortly before the Kolb sale and asked me to look at my ribs and verify they were OK as others had found the tang issue. He promised to replace them if they were incorrect. At the time, my ribs were tucked away in a moving box, buried deep beneath a mountain of freshly moved stuff. I was struggling to keep my family under roof and ribs and tangs were not on my priorty list. It wasn't until I reached the wing building phase did I realize what he was talking about. Sure enough, they were on the wrong side. After a round of waivers and price negotiations, I had TNK cut the tangs off and reweld them to the proper side. Again, after a long idle period, I attempted to install the ribs in the wing spar and found they weren't even close to being square. More waivers, more negotiations, and finally they were welded correctly. Despite TNKs lack of interest, they did a great weld job in the end and the ribs installed per plans.

This is the second Kolb aircraft that I have built. My first plane was a '85 Firestar that I learned to fly in and flew for over 5 years. I sold that plane to fund my Private Pilot license venture and it is still flying out of Fink Haven in Williamsport, PA. Though I am a low time GA pilot, my most memorable and enjoyable flights were in my Firestar. My desire to share those experiences led to the purchase of the two-seat Slingshot.

Here are some Slingshot characteristics:

• Empty Weight: 360 lbs.
• Gross Weight: 850 lbs.
• Wing Span: 22 ft.
• Wing Area: 110 sq. ft.
• Engine: 582 Rotax
• Cruise Speed: 87 m.p.h.
• Stall Speed: 30 m.p.h.
• VNE: 125 m.p.h.
• Construction: Steel, aluminum, conventional fabric covering

Not exactly Part 103, the aircraft will be registered as Experimental.

Unfortunately, the early build pictures were on the then, popular 35mm format and didn't scan well. I'm trying to pick up where I left off, with one wing partially complete. The pictures may not be chronologically correct but hit on the main tasks.

For more photos see ClubPhotos

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