About The Project:

The airplane is a home-built, scratch-built Zenith CH 750 STOL. Building from plans/blueprints is a challenging way to build an airplane, since most of the parts you use to build it are not prefabricated. I chose the Zenith CH 750 STOL for its rugged design, its STOL (Short Take-Off and Landing) characteristics and its aluminum construction. Zenith Aircraft Company has designed this airplane so that it can be built from scratch or from a kit by the average person. They provide excellent technical support for both kit and scratch builders. In addition, I'll be installing a 1965 Chevrolet Corvair 164 cid horizontally opposed, air cooled, 6-cylinder engine, with special conversion parts to make it suitable for airplane duty. This is what the airplane will look like when I'm done, although I'll have a different paint scheme:

Follow my progress below!

Tuesday, May 24, 2016

Forming the Landing Gear Channel

My sheet of .040" aluminum is getting pretty banged up in the shop. I just don't have enough space in the garage to keep full sheets of aluminum stacked against the wall without banging into them. It's too inconvenient to keep rolling them back up, only to have to unroll them to cut a part. So I decided to use up the .040" and get it out of the way before I render it completely useless with scratches and dents. In my last post, I linked to a videos series where I detail how I modified my bending brake and progressively added new bits/pieces/modifications at each step of the way. After the first bend, I had to continue to upgrade and modify the brake to be able to do each new bend, just on that one part (Landing Gear Channel). However, I now have a brake that (hopefully) can bend every part I have left in the plane, including the complicated "hat" sections. Here are some sequential pictures of the Landing Gear Channel forming process, starting with brake modifications:

New bending arm made from 5/8"x4" steel slab with original 3"x3" angle used as leverage helper. Modified Brake Hinges made from 3/4" solid rod & 3/4" schedule 40 pipe:
 

 Extended truss-style bending arm handles for more leverage and center load spreading:

2x2x1/8" square tubing used as load bearing truss for clamping bar. 3" bolts through screws allow for adjusting tension:


Landing Gear Channel part blank - 1105mm x 293mm:


Outer flanges (23mm wide) bent already, now overhanging face of narrow bending arm:


Larger Channel Bend sticking out back of brake:

 

Fully formed part, sort of a "hat" section of channel:
 

View of full 1105mm length of formed Landing Gear Channel. Both ends are within 1/2mm tolerance specified in blueprints.
 

It took a total of 4-6 weeks (mainly due to down time) to get the welding/modifications done on the hinges and bending arm, plus progressive modifications as I went to get the whole gear channel bent. This was the most difficult part to make thus far, mainly because I kept having to stop & figure out how to modify the brake to get each successive bend. But I'm pleased with the results, and hopefully I won't need to modify the brake any more!
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10 comments:

  1. UnknownMarch 7, 2017 at 4:55 AM

    hi, my name is Liang.
    I have a question about the main landing gear of CH750.
    Is width of the main landing gear 4.5inch?

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    Replies
    1. GregMarch 7, 2017 at 1:43 PM

      It is 5.51 inches/140mm.

      Delete
    2. UnknownMarch 8, 2017 at 4:22 AM

      This comment has been removed by the author.

      Delete
    3. UnknownMarch 8, 2017 at 4:23 AM

      wow，it's a unusual size for gear (spring).
      I thought that the sizes of gear are 3, 4.5 and 5 inch normally.

      Delete
    4. GregMarch 8, 2017 at 8:19 AM

      Yeah, I have no idea what would be considered standard on other aircraft. This spring gear is the same for 750 STOL, 750 Cruzer and 650, as far as I know.

      Delete
    5. UnknownMarch 8, 2017 at 11:34 AM

      hum~
      definitely not the weight I guess ~
      there is no ch750 or ch650 in my flying club
      Can I know how heavy the gear is?

      Delete
    6. GregMarch 8, 2017 at 4:03 PM

      They are heavy. Based on the average weight of 6061-T6 (.098 pounds/cubic inch), and the volume of the gear, it weighs about 23 lbs or 11.34 kg, if my math is right.

      Delete
    7. GregMarch 8, 2017 at 5:46 PM

      I should add, that only includes the 3/4" thick aluminum spring gear itself, not the added weight of the wheels, brakes, fittings and bushings.

      Delete
    8. UnknownMarch 11, 2017 at 10:26 PM

      oh~ok，thank you~!

      Delete
  2. UnknownMay 11, 2020 at 12:53 AM

    Good work....

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