Belite Aluminum Ultralight Aircraft Cabin Construction, #3

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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!

Wild Mustang Horses in Kansas Flint Hills

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Quickly stated:

The shop gang installed the removable fairing on the back of the UltraCub, which made it look like a baby cub.  I was eager to fly it.

I flew the UltraCub from home base out to the Flint Hills (which are east of Wichita), where I took high res pictures of Wild Mustang horses, then returned home.  It was a 90 minute flight; and I used 2.5 gallons gasoline.  I returned with 90+ minutes fuel reserve at home base (slightly more than half tank remaining).  Fuel consumption:  1.67 gallons per hour.  Estimated fuel economy:  about 34 mpg.

Gentle Readers, the horse pictures are eye-popping, and you have to go to our belite flickr account to see them all.

Here's the link to the Wild Mustang horse photos on Flickr.  I have a couple of selected photos from the flight below.  The remainder of the wild horse photos (and there awesome photos of the horses) are on flickr.

Flint Hills, photo taken from Belite UltraCub ultralight airplane.

Wild Mustang Horses, photo taken from Belite ultralight airplane

Also note that that the four stroke UltraCub is now flying with the removable tail fairing attached:

Belite UltraCub ultralight airplane with four stroke engine

Walking the UltraCub 4 stroke ultralight airplane back to the hangar.

I used to do this flight in my Flight Design CTLS; it is absolutely a gift from God to be able to do it in the Belite.  I'm back to cruising around.  I'm planning cross countries to Oshkosh and Idaho.

Total time in the Burgundy UltraCub to date:  5.4 hours.

Here's the map of this adventure:

Wild Mustang Flight to the flint hills and back.

Flight speeds outbound to the flint hills averaged 65mph; return flight averaged 45mph.  Average groundspeed:  about 55mph.  You can see the variance on the position spacing above.  Cruise RPM varied from 2500 to 2700 rpm.

Ultralight Cross Country?

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Personal note:  Thank you, Larry, for reading my blog. I did take that flight this afternoon, as I suggested I would.

Readers:  Please allow this post to wonder and wander around a bit, just as I did on a cross country flight in the burgundy plane.  Details on that flight are later in this post.

After I got to the airport shop this afternoon, I set to work on our production prototype of our new aluminum cab, which, when combined with a fuel efficient four stroke engine, produces the best ultralight aircraft on the planet.

There. I said it.  A boast:  "The Best Ultralight Aircraft in the United States".

There are seven reasons why this is so:

Engine Selection:  4 stroke aircraft engine with reliable operation and low fuel consumption
Airframe:  Aluminum; easy to build, lightweight
Utility:  Great short field performance; off - airport ruggedness
Flight Characteristics:  When trimmed, flies hands off; turns easily.
Extras:  Our carbon fiber expertise allows more strength, even lighter airframes and more options.
Covering:  Our Oracal process is producing the most beautiful airplanes, with less cost and less time than all other traditional aircraft coverings.
Cross Country:  I'll get to this last.  I had a great time flying away from the airport, then returning as sunset was imminent.

1.  Our engine selection.

We picked a 4 stroke engine built by Hummel Engines, and as their website states, this is "reliable four stroke power", and has been in use for years in various aircraft.  Our engine was ordered with all new parts, including aluminum Nicom cylinders.  We also ordered the largest bore and stroke that Hummel offered, and it has quickly proven to be a perfect choice for Belite.

Although this engine is rated at 45HP, we are using it in a derated manner, by limiting RPM to about 3150 RPM.  This gives us around 38HP at full throttle, which appears to be adequate to produce the maximum cruise speed legally allowed under US ultralight aircraft regulations.

This engine weighs 88 pounds, including carburetor, exhaust pipes, and dual ignition.

Christian Stratton had been working hard on fitting our Burgundy plane with a new firewall.  We'd been challenged to accomodate the sharp looking opposed cylinder engine in the Belite, and to eliminate Center of Gravity (CG) issues, the engine had been placed in a manner such that the magneto was poking into the cabin.  The new firewall fit beautifully; here's a photo of the revised engine installation and firewall.

4 Stroke engine on Belite Ultralight Airplane

And we provide some great two stroke options as well; nothing beats a Hirth F23 for raw stump pulling power.

2.  Our aluminum airframe.

The fit and engineering quality on our aluminum cabin is just amazing.  Weighing in at about 22 1/2 pounds, this cabin sets a new benchmark for ultralight aircraft.  Pictured below is a cabin being prepared for a customer here in the state of Kansas:

Aluminum cabin assembly for Belite ultralight airplane, with Oracal covering

Let's take one peek inside this cabin, and look at the box construction along with the fit of everything.  The in flight storage compartments are on the lower left side:

Aluminum cabin for Belite ultralight airplane

3.  Belite has utility on and off airport.

When equipped with spring gear and appropriate tires, I've had no end of fun landing Belites in the neighboring uphill hayfield.  Great fun!  Caution -- good results require great skill.

Hayfield landing in Belite Ultralight Aircraft

I did a fun post on this topic.  Read the Hayfield Post Here.

4.  Flight Characteristics.

The new UltraCub is flying by stick control only (see the video demonstrating this here.)  Alternatively, on my flight earlier today, I kept my hands off the stick and bumped the plane around using rudder pedals.  Take your pick.

5.  Extras.

I've enjoyed engineering some other options into the Belite.  Our carbon fiber spars are stronger and a great choice for customers who want less weight and more wing strength.  I'm working on some more options for the future; here's an example of a prototype Stabilator rib.

prototype Carbon Fiber rib for stabilator on Belite Ultralight Aircraft.

The pictured rib weighs about 2.1 ounces.

There's lots of other extras, but I won't belabor the point.  Read more about our airplanes on this blog or on our Belite website.

6.  Our covering process.

We're using Oracal, a vinyl covering which looks spectacular and easy to apply.  We've been using it for a couple of years.  Other automotive, aircraft, RV, motorcycle manufacturers use similar products for applying graphics onto pre-painted surfaces.  We take it a step further, and cover the entire airplane with it.

7.  Cross Country?

I wonder what the possibilities are.  Based on initial fuel burn analysis, fuel burn with the 4 stroke engine is running around 1.7 gph at low cruise.  I've got to get that number nailed down, along with 'cruise' speed at various RPM's and fuel flows.  Assuming fuel flow of 1.7gph with a 50mph speed, we've got a range of 145SM miles to dry tanks.  Combined with neutral or tail winds, there is a pretty good opportunity to go a long distance, and beat land transportation in the process.

Earlier today, I took off in the burgundy Belite UltraCub and headed north, into a headwind.  I decided to fly  30 minutes northbound, then turn around and head home.

Here's some photos I took along the way:

Cross country in a Belite Ultalight Airplane

View of small town (Furley, KS) on a cold December day

Watershed ponds shrinking in size, due to drought

Farm house and wheat field

Actually, this pond is doing OK.

Harvey County east lake, photo taken from Belite Ultracub with 4 stroke engine

I turned around and headed home.  It took 30 minutes at low cruise, into the headwind, to get there.  I upped the power and climbed into a nice tailwind heading home, which took 20 minutes.

I'm starting to think, again, of flying to Oshkosh next summer in a Belite Ultracub.  We'll see.

Total Time in the burgundy plane to date:  3.9 hours.

The following day, I took the Belite UltraCub out to the flint hills to take hi-res photos of wild mustang horses.  You can read about that HERE (click).

Belite Aluminum Ultralight Aircraft Cabin Construction, #2

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 the second section on building an aluminum cabin for a Belite ultralight aircraft.  We're well on our way to finishing an awesome cabin for a single place airplane.  When completed, this cabin will weigh about 22 1/2 pounds and will match the look of other experimental (and factory) airplanes costing much, much more.

The first section in this series is HERE.

All caveats and warnings from that section apply in this section as well.  Remember, under federal law, you are personally responsible for ensuring the safety of your ultralight aircraft every time you fly, so do a good job.

Start by cutting two lengths of structural aluminum.  Each piece looks like this:

Short length of angle aluminum.

And each piece fits on the left or right side of the front cabin cross box assembly, as seen in this photo:

Short length drilled and clecoed in place.

Note that a long clamp is being used to pull both sides of the cabin snugly together.

Front Cabin Cross Box with both skins clecoed in.

Now it's time to clamp in the bottom gusset.

Bottom gusset clamped in place.

Bottom Gusset gets a few rivets.  (Cabin is on side.)

Be judicious in the use of rivets on the bottom gusset.  In the above photo, there are a couple of rivets placed (mistakenly) which were immediately drilled out in order to allow the floor pans to slip into place.  However, the objective is to get all of the bottom rivets in, so that the cabin assembly can set on the bottom and moved around without dragging the bottom tips of all of the clecos.

Floor pans as received and after bends.

Your pair of floor pans need to be bent into shape, as shown above.  The pre-cut relief slots make this easy to line up and do. Also, if you have shorter legs, you may wish to drill out and reset the position of the rudder pedal and brake bearing holes.  In general, the position of the holes should work well as set for pilots between 5' 8" and 6' 4" in height.  Shorter pilots may use a back cushion on their back seat, and anyone with truly short legs should consider resetting the pedal location.

Floor pans clecoed in place.

Make sure your floor pans are put in square to the cabin assembly, as one end does not have matching drill holes.  Also note that doubler gussets have been clecoed in on each forward corner.

Bottom front section riveting.

Above is a photo that shows what it looks like after riveting the bottom front section.  Note that many holes have been drilled out for 3/16" rivets.  Also note:  look through the remainder of the assembly instructions, as a metal sheet will be slipped under one side of the floor pan.  The metal sheet is the bottom of the mid cabin storage cabins, and its front edge has to slip under one of the floor pans and also under one of the front landing gear gussets.

Front Landing Gear Gusset.

To be continued.