Belite Aluminum Ultralight Aircraft Cabin Construction, #4

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I hope you had an awesome Christmas!

Shortly before Christmas, I had an amazing two hour flight in the Burgundy UltraCub.  I flew out into the flint hills again, and made a video of most of the flight.  I took lots of photos of sights along the way, including wind turbines near Beaumont, KS, and a friend's house out in the flint hills as well.  I'll be posting an edited copy of that video soon; along with some of those photos.

When I returned to home base after that flight, the plane still had over a gallon of gas in the tank, and I've now accumulated 7.9 hours in the Burgundy UltraCub to date.  I thoroughly enjoy the look and sound of the 1/2VW engine.

We will install a brand new cabin in the Burgundy UltraCub over the next 8 weeks, so that when it goes to Florida for Sun N Fun, it will be absolutely up to date with our current design.  (The original cabin was hand built without the benefit of CNC placement of drill holes; lots of stuff didn't line up well; and some of the features in the final cabin design were missing; PLUS it had extra tubing and weight where some dimensions were screwed up...)  So stay tuned on that...

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Today I am posting Episode 4 of the ongoing saga of how to build a Belite cabin.   The actual construction of this ultralight aircraft cabin goes very rapidly, and everything lines up, and it's just thrilling to build a structure which is so very light and very strong and very aesthetic all at the same time... and that is a lot of ANDS.

For links to earlier Episodes, just search "construction" in the search window of this blog.  The search window is on the right side of the blog.

Some of the following construction jumps around a bit.  I have two reasons for this:

a)  It beats the boredom of just working on one area of the cabin.
b)  It gave me something to do while waiting on our ShopBot to cut more CNC parts.  You won't have this problem, as you'll have all the parts in front of you.

Let's cut two thin wall 1", 34 1/4" tubes.

You'll need two thin wall 34 1/4 inch square aluminum tubes.

And also a 23 7/8 inch tube of the same material:

And a 23 7/8 inch tube

The 23 7/8" tube clamps in place along the top of the rear gusset.  The longer tubes rest on each side side skin.  One side and the rear is visible in the following photo:

Rear tube and side tube

Rear tube clecos

Front Diagonal Supports

Front Diagonal Support clamped in place

Front Diagonal Support with rivet and clecos

Front Diagonal Support fully riveted

In a similar manner, cut and fit two Rear Diagonal Support, then clamp and cleco in place.

Rear Diagonal Supports.

Rear Diagonal Supports, riveted in place.

Now let's move to the front of the cabin and finish out most of the rivets in the Front Cross Box.

Front Cross Box rivets, looking from front of plane backwards.

Front Cross Box rivets, from other side.

Now, fit the Front Cabin Cross Tube Gussets.  Yours are probably pre-notched, but I had to notch mine.

Gussets for Front Cabin Cross Tube.  

Although the above photo only shows one gusset, the gusset is actually doubled (one on top of the other).  It's time to pull some rivets:

Gussets with rivets and clecos

Now our focus shifts to installing four Side T Gussets, two on each side of the airplane.

Side T Gussets clamped and clecoed.

Side T Gusset riveted in place.

Please make sure you've placed clecos in the rear tube, as shown below:

Clecos on rear tube

Gussets need to be added on each Rear Diagonal Support.  A bend is placed in each gusset prior to placement.

Rear Gusset for Rear Diagonal Supports.

Another view of gusset for Rear Diagonal Support, clearly showing bend

Rivets on the gusset

Ensure that rivets have been placed on the bottom of the rear fuselage.

Rivets on bottom of rear fuselage.

Belite Aluminum Ultralight Aircraft Cabin Construction, #3

Please note: James' blog has moved to a Wordpress site. To access it, please visit http://jameswiebe.wordpress.com/. All posts have been transferred to the new site, and all new posts will only be accessible via Wordpress. Thank you for your interest!


This is a third in a series of article on how to build a Belite aluminum cabin.

The first in the series may be found HERE.

The second in the series may be found HERE.

Random reminder:  All of the standard warnings and disclaimers apply.  Flying a Part 103 Ultralight Aircraft may be dangerous or deadly.  These aircraft are not certified under any FAA regulations.  They are not built from certified aircraft materials.  You are required to sign our standard liability release before we'll ship you a plane or a kit.  You take full responsibility for your aircraft and its operation, per federal law, and per our liability release, no matter who built it.  (Us, you, or someone else...)

Sigh...  American liability...   Now, onward.

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The cabin in the Belite Ultralight Aircraft has several noteworthy, eyebrow raising features.  For instance, I am very pleased with the number of storage / baggage compartments which I've been able to design into the plane.

Before we get started with today's construction, let's look at some photos which preview the results of your construction project!

Belite Ultralight Aircraft Cabin Assembly, with teal blue Oracal

Three individual storage / baggage compartments, with solid aluminum bottom

Chart compartment, on left side of cabin

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Now, directly on to the construction.  We'll pick up where we left off in the last installment.

Cut thin wall square tubing for the front seat cross box, and then cleco the two skins to that tubing.

Thinwall tubing for Front Seat Cross Box.  Note one short center piece missing.

You'll need to cut and fit the short tubing piece and cleco it in place as well.  I'm sorry it missed the above picture, but it is in the next picture, below.

Skins, clecoed to tubing for front seat cross box assembly.  Short piece is clecoed inbetween.

Now we'll work on the baggage divider for the front compartment.

Baggage Compartment Divider

There are three baggage dividers.  Select the one for the front compartment, which looks like the photo, above.

Front Baggage Divider, after bending tabs.

After bending tabs in a box break, the divider will look like the above photo.  The divider is then clecoed in place, and it will help to support the front seat cross box assembly.

Front Baggage Divider, clecoed in place.

Front Baggage Divider, riveted in place.

Front Seat Cross Box, riveted together

Front Seat Cross Box, riveted together with quartering view

Then we proceed to the Middle Seat Cross Box.

Middle Seat Cross Box, cleco assembly identical to Front Seat

Now we need to make a notch in each longeron, immediately after the Front Seat Cross Box.  Make a mark as shown below:

Mark in longeron.

Cut notch in longeron.

The notch will allow us to bend the longerons up, about 5 degrees.  The actual angle is determined by the precut side skins, which are coming soon.

Side skin being cut.

Side skin clamped onto side of cabin assembly.

The bend in the side skin determines how high to bend up the longeron.  A clamp in the above photo is holding the longeron against the side skin, so the angle is perfect.  Note the clecos already holding the side skin as well.

Closeup of overlapping star gusset.

Note how everything overlaps.  The top door side skin (not yet installed) will overlap into the same area and determine the final angle of the vertical longeron, and that is why its holes have not yet been drilled through.

Even more clecoes in the side skin, while Lucky snoozes.

One of our shop cats got in the photo.  Our cats are named Second Chance and Lucky.  Both are gorgeous and friendly.

Bottom Cross Lift Strut Tension Member and rear structural angle parts

Cut the three parts as shown, above.  The bottom Cross Lift Tension Member is 1x1x.063 6061T6.  It is NOT thinwall tubing.  At 6Gs of (hypothetical) lift, this piece is carrying around 5,000 pounds of tension.  (And on paper, it's good for it.)

Error in side skins

When this production prototype was under construction, the side skins did not have a rear 1 x 1 notch.  Yours should have a notch, but the longeron will still need to be cut out, so that they look like this:

After notchout and longeron cut.

The cross member will form the base of the rear cabin.  Construct the rear cabin cross box:

Rear cabin construction begins.

Rear Cabin Cross Box with rear skin.

Add the thinwall tubing.

Thinwall tubing for top of Rear Cabin Cross Box.

Thinwall tubing placed into Rear Cabin Cross Box.

Now, it's time for some riveting.  Note rivet sizes as always, based on the photos:

Rivets on Cross Boxes.

More rivets hold side skins and cross boxes.  WARNING:  Extra rivets shown!

The warning refers to a few extra rivets which have been placed, and which will have to be drilled out to attach Rear Fuselage Gussets.

The Cross Boxes must be aligned perfectly with the pre-drilled holes on the side skins.  I failed to do this on one of the Cross Boxes in this production prototype, and you can see that the middle Cross Box is leaning towards the camera, perhaps by one degree, in the photo below:

Mis-aligned Cross Box, (very slight).  Don't make this mistake!

Lucky strikes another pose, with rear of cabin assembly

Another view of rear, this time with rivets drilled out and replaced with clecos.

This is a good time to stop for the day.  The Belite ultralight airplane cabin is beginning to look like a cabin!