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All my building experience is limited to Van's RV's so I have no experience with building tube and fabric or "plans building". I have much to learn so take everything I write with a grain of salt and reasonable skepticisim.
I do not intend to follow a "traditional" path for the construction of #88. I intend to employ low level technology and $ to reduce the construction time and difficulty where possible and practical. By low level technology I am referring to CAD, laser, waterjet, CNC. For example:
- I have purchased a complete wing spar kit from Jerry Kerr.
- A rib kit from Mr. Bartoe.
- Brunton Flying Wires and Drag wires from Harvey Swack.
- CNC profiled tube kits for the fuselage, tail feathers and landing gear from VR3.
In addition I have converted all of the wing fittings, brackets, links, lugs etc. to CAD and had them cut by water jet. I have designed a laser cut wing spar drill template/jig which positions the five spar components so that all of the holes can be drilled in a complete spar as an assembly. I plan to continue converting as many parts as I can to CAD so that I can reduce the "hand-made" components to a minimum.
Note: As of June 2015 I have over 100 CAD files which provide 600+ water jet cut parts for the Skyote.
While it takes a little time, converting the design to CAD is a great way to truly understand the drawings. plus a huge amount of information has been extracted from the rather complex drawings. This can be a great help to others in understanding and interpreting the design.
The Skyote is uniquely suited for conversion to CAD in that a "computer" was used in it's original design. I have read that Mr. Bartoe used a HP calculator to "compute" the design and dimensions of the Skyote. The plans show all of the critical dimensions to three decimal places for X,Y and Z axes.
Amazingly, when I put the design into CAD the resulting 3D models agree with Mr. Bartoe's thee decimal place dimensions about 99.9% of the time. I have found one discrepancy but less than 0.030"!
If you want to build your Skyote as cheaply as possible, or if you enjoy handcrafting the same parts over and over again then my approach to building is not for you!
If you want to build your Skyote in the minimum possible time with highly accurate parts then this approach may be the answer. I personally get a lot of satisfaction out of organizing the project so that it can be produced accurately. Hopefully some of this work will prove useful to others in the future.
Sunday, August 12, 2012
Fuel Flow Test
I ditched the "two compartment" tank I had previously installed in favor of this approach which uses a wedge shaped "basement section" added to the standard tank. It holds 3-1/4 additional gallons which, combined with the 12+ gallons in the main and wing tanks, should provide 2 plus hours of range with a 45 min. reserve remaining.
I set up a fuel flow rate test using all of the actual valves, hoses, fittings, gascolator, etc. as removed from the airplane.
I used NAPA parts cleaner fluid (high grade mineral spirits) in place of avgas for all the obvious safety reasons.
I performed a series of tests with varying amounts of solvent in the tank and with differing vertical dimensions between the bottom of the tank and the hose outlet to
the carb to simulate different nose-up attitudes. AN-6 hoses and fittings are used throughout. I tested with 1,2,and 3 gallons in the tank and at effective nose up attitudes of 12.5 and 20 degrees. !2.5 degrees is the three point attitude for my airplane. I timed the flow (min/gal.) for 1 gallon at each of these conditions. This time divided into 60 ( min./hr )gives the equivalent average gph flow rate for one gallon at the specific conditions tested. (whew!)
I was interested to see what effect the "red cube" fuel flow transducer would have on the flow rate. The good news is that the system will flow sufficient fuel to the carb for all conditions with the transducer included in the line.. The last remaining gallon flowed from the tank at the average rate of 16 gph at a 15 degree nose up attitude. At 20 plus degrees nose up, the flow rate was still in excess of 10 gph for the last gallon.
When I re-install the tank in the airplane, I will run the same tests with the hose hooked to the carb with the plug removed from the bottom of the float bowl. This will determine how much restriction is added by the "needle and seat" orfice.
My fuel valves are set up to allow for "either tank", "both tanks" or "all off" positions. Proper planning will have the last remaining fuel in the wing tank, eliminating concerns about low head conditions.
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