Canadian Flag Blowing In The Wind Ron Leclerc Zenith CH701 Construction Log


Zenair CH701 STOL Aircraft...
CH701 STOL

Winnipeg

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Welcome to my Plans Built Amateur Aircraft web site...

This is the construction log of a plans built Zenith STOL CH701 designed by Canadian Chris Heintz.... Designed to meet the requirements and standards of the Canadian Advanced UltraLight Pilots needs. It can be built as an Amateur Built Aircraft and flown as an Advanced Ultralight as long as the gross weight does not exceed 1200 lb.

This aircraft offers great performance and off-field capabilities, and is easy-to-fly with many pilot-friendly characteristics, including a low stall speed... as well as short-field performance of well under a 200 feet. I'm a plans builder... building from scratch, making parts as I go along. Some specific parts that I can't make will have to be purchased directly from Zenith Aircraft, such as landing gear, windows, windshield, and possibly the fuselage cabin. Received my construction plans from Zenith Aircraft Company on April 4, 2007... looks good, time to begin.

There will be some modifications done to improve the slow speed handling capabilities... which is a problem mentioned by many builders. The main wing will be extended by 2'- 6" for a total wing span of 29'- 6" and VG's(Vortex Generators) will be added. This will add 1'- 3" to each wing at the tip. The rear spar channel of each wing, will also be strengthened and modified with only 2 pieces of 0.032... an I/B and O/B channel as opposed to the 7 required by the design. This will result in less time to build, less prone to errors, resulting in a straighter wing and cleaner trailing edge. The main rear ribs and root rear ribs will also have to be redesigned to take into account the new spar channel. Some of the other part modifications that will be required... are the flaperon arms, the upper rear strut fitting and a spar channel doubler added at rib #4. This redesign is similar to the new CH750 wing, which has a 50mm deeper chord aft of the trailing edge. It should be noted here also... that the root nose ribs and main nose ribs of the CH750 wing are identical to the CH701. The flaperons of course will also have to be extended 1'- 3" on the outboard end of each left and right flaperon.

No slats will be installed... but VG's(Vortex Generators) will be added the full length of the wing at approximately 8% of the wing cord. The guys at STOLSPEED Aerodynamics...in Australia have developed the use of VG's(Vortex Generators) with an extended wing and flaperons for the CH701. Zenith have also developed their own design version made out of 6061 T6... 0.020 aluminum. STOLSPEED'S are made out of some sort of plastic! After reviewing what is available and how they are made... I decided that they would be a good addition to the CH701 project. So I have come up with a simple method to make them out of 0.025 6061 T6 aluminum... similar to Zenith's(0.020 aluminum). Check out our VG Construction page. They turned out quite well, very easy to make... and better then expected.

As a result of the extension of the wing, attention was turned to the tail feathers... Zenith had extended the width of both the elevator and horizontal stabilizer on the CH750. So the CH701 elevator and horizontal stabilizer width, will also be extended to a full 8'- 0" in width... based on the original design wing/stabilizer width ratio of 3.7241(from the design width of 7'- 4")... with VG's(Vortex Generators) added to the underside of the elevator at the Leading Edge.

701 Modified Horizontal Stabilizer and Elevator!

This stabilizer modification and elevator modificationis in response to some changes made to a 701 in Australia by - JG of StolSpeed Aerodynamics! JG and his partner Hans acquired the Stabilizer and Elevator from a damaged Savannah(701 clone) aircraft and installed them on Hans 701. Now Hans has over 800 flying hours on this aircraft and was never satisfied with the low speed handling as compared to JG's Savannah. JG's Savannah has some features that make it a very stable flying aircraft at low speeds and faster also. Now Hans tried to modify his 701 similar to the Savannah by going to a longer wing, adding VG's to the wing and also adding VG's to the leading edge of the elevator! All of these mods were very positive... but the low speed capabilities still presented a problem... so there was only one thing to do and that was to change the stabilizer design to a more streamlined design(not the inverted airfoil design like the 701) as compared to the Savannah. Well Hans got the chance to do this mod when a Savannah Stabilizer and Elevator became available. The Stabilizer and Elevator mounts onto the 701 very easy with a few mods since both the 701 and Savannah both evolved from the same design source. Check out how the 701(Chris Heintz) and Savannah(Max Tedesco) designs evolved and the paths each has taken by the designers!

Construction Update May 2012: Had a small nagging problem! The stock Firewall was to narrow(28.75") for my engine! My VW Type 4 engine is 29.5" wide which makes the stock firewall impossible to use. So I sat down and did a little research and soon realized that I could make the firewall 32" wide by adding 82mm to the FWF... this would result in modifying 24 parts which is easy to do. Now I had earlier built my Instrument panel 50mm higher... so it was a no-brainer to make the firewall 50mm higher at the same time. BTW, I have both the stock firewall and modified panel built... so now have to redo them. One huge benefit resulting from making the FWF wider by 82mm... is that the cabin is now 44" wide, and by adding bubble doors(another 4"(100mm)) it sure makes for a nice wide cabin.

Beanie Mod May 2012: A Beanie Mod will also be done to the cabin roof similar to JG's [Stolspeed] Research and built by Joe Spencer. This open area above the cabin between the wing roots, is a major problem and a concern... and has never been addressed by Zenith! It should be noted here now that Zenith has since copied this mod and has made it standard on the 750... you cannot get a 750 with the flat roof now! The initial research, development and tuft testing was performed by JG on a heavily modified 701 with dramatic results in the slow speed handling capabilities of the aircraft... which Zenith sat up and took note off, and have yet acknowledge that the credit for this mod is due to JG and Joe Spencer!

 
 

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