Details on Ultralight Honeycomb Cabin

I'm now 34 hours into the build of a Chipper ProCub / UltraCub 2022 prototype aircraft. The design has the following characteristics:

• Safety first, with an enclosed robust cabin
• Compliant with FAR Part 103
•     - single seat
•     - empty weight of 254 pounds
•     - stall speed of 28 mph or less
•     - full power cruise speed of no greater than 62 mph
•     - maximum fuel capacity of 5 gallons
• Easy to build
• Classic good looks, unapologetically an airplane 
• Inexpensive
• Quick building
• Folding wings
• Fantastic flying manners
• STOL capability is a plus.

 A shoutout to my friend Landon!, who painted the seat in the photo. This seat was made for and first flown in my skydock design, and it looks great with the old Belite logo and gloss blue color. Everytime I do work on an ultralight, I find this seat and set it in the design to see how things are shaping up. I do have a list of brief skydock videos,

https://youtu.be/eI_arV4mu_A

https://youtu.be/5Q_JC0GhLQw

https://youtu.be/qJH9cKjkH5I

but I digress. Back to the business at hand. Here's the visual progress report on this Saturday:

Below is a closeup on that seat. It is resting on two honeycomb bulkheads, along with the backrest honeycomb cross piece. The honeycomb has been cleaned up with an aluminum cap on the heavier 3/4" rear bottom honeycomb and backrest cross piece. The front cross piece has a vinyl cap. Look carefully into the small 'windows' in the sides of the cabin, and you can see where I've begun to install aluminum tape over exposed honeycomb.

Another photographic point of view. The cabin is currently in 'flintstone' mode as the bottom skins aren't yet installed.

Yesterday, I designed a couple of new gussets for the top of the cabin. They are highlighted in green:

Today, I cut them on the shopbot and installed them. Here's the forward gusset. You can see the mirror part on the opposite side of the cabin as well. I pre-primed them before I installed them. The tab is intentionally overbent to keep the sharp edge away from the pilot-occupant.

For that matter, all of the gussets are bent with safety in mind. The tabs almost always face away from the occupant.

I already mentioned the backrest cross support piece. It is fabricated from 3/4" honeycomb, and then held in place by pairs of aluminum angles which were bonded using epoxy. I prefer 3m 2216, but I had original formula JB Weld on hand, so I used it.

The photo shows the parts bonded together and held with temporary bolts. As the rear fuselage side skin is not yet installed, these bolts will eventually be replaced and redone with washers along normal practice lines.

Changing my focus to the front box, I'm really pleased with the quality of the CNC parts; the general fit, and the way this is beginning to look. I'm excited for how things will be when the windshield and engine cowl are added. I'm designing a new cowl which reflects the fresh new look of this airplane; I won't be using the old radial bump design anymore.

I mentioned earlier that the cabin was still in flintstone mode (no bottom skin yet); these photos show the detail of the structure as seen from the bottom.

Make sure you've seen my youtube videos which show this evolving project:

This one talks about adding metal skin to the rear fuselage in CAD:

https://youtu.be/VmcgWRY3bb8

This one talks about using Sketchup to make this design:

https://youtu.be/rUkmoWByCws

Finally, as I am in bootstrap mode, I get a lot of enthusiasm and deeply appreciate my patrons. $10 per month gives you the rights to the blueprints for this plane (terms and conditions apply) and $35 per month indicates that you plan to purchase a kit. $80 indicates that you plan to purchase a Ready To Fly; I've set the price for the first 3 RTF planes at $30,000 in taildragger configuration and basic instrumentation.

Become a patron here:

www.patreon.com/jameswiebe

Thanks for reading,

P.S., this is how the cabin CAD looked on December 12, a little less than one month ago. It's come a long way!