Rear aluminum fuselage assembly

Here's some photos showing the buildup of the rear of the fuselage in our aluminum ultralight airplane.  Most of the aluminum is 2024 series, but some is 6061.  The amount of labor to get to this picture is about 20 hours.  Still remaining is gusset work, along with a few odds & ends. 

I love clecos!

This is not hard work.  It is a blast to lay it out and have it look like an airplane within two days.

The rudder comes pre-welded, as shown in the photos.

I'm in this picture, but you can't see me.  I'm holding the board up from behind.

Gussets not shown.  The bottom wedge with all the clecos is actually 4 layers of aluminum.

I love the rear section of the fuse.

This bulkhead will have the nylon bearing block for the elevator push pull tube.

Gas tank platform.

One last look at the tail.

aluminum fuselage update

Here's some photos showing some of the ways our fuselage design has mutated from 4130 steel.  I've also made some comments on strength.

The front of the fuselage is made from 6061T6 aluminum, and is welded.  The rear of the fuselage is made from 2024T3511 aluminum, and is riveted.

The hallmarks of this design is that it is very light, very strong, and easy to assemble.  Let's look at some pictures.  The first picture shows that the primary vertical members are 1.0" aluminum square tubing, with .063" walls.  Although the temper is 6061T6, the welding is assumed to reduce the strength.  This particular tubing doesn't have the heavy loads.  However, it is also a primary safety mechanism to enclose the pilot in the event of an accident, so we still want it to be strong.  Assuming 0 temper, the strength of this material is about 4,500 pounds per tube cross section.

1" square tubing used in Belite ultralight aircraft

 

 

The front section of the fuselage is where the engine mounts attach.  We've reinforced this section with 4" gussets.  Here is a gusset at the top of the front fuselage:

Gusset reinforcement

 And here is a gusset on the bottom of the front fuselage:

Gusset reinforcement is on bottom of fuselage

 

 

Now let's look at the front spar crossover.  It is constructed of aluminum tubing (about .080 wall) with reinforcements in both axis.  As a result, it has a critical length of about 12 times its diameter, which means that the effects of "Euler's Buckling" have been reduced or eliminated.  At normal loading, this spar crossover has about 650 pounds of force pushing through it.  At a 4G load, it would have around 2600 pounds of force.  Assuming 6061T0 temper (welded), the cross section strength of this material is about 4000 pounds.

Front Spar Crossover with reinforcements.

Now let's take a look at the rear spar crossover.  We've reinforced it with some 1" square material.  The failure strength is substantially stronger than the front spar.

Rear spar crossover with reinforcement

 

 

 

Here's another view of the rear spar crossover:

The above photo shows the bracing.  The braces help prevent the cockpit from torsionally twisting.

rear spar crossover with bracing shown

The pilot's seat also gets some strengthing:

0.5 x 1.0 aluminum tubing added to pilots seat

Tricycle gear versions of our planes get extra cross channels on the bottom, along with more bracing in the side cabin area:

Tricycle gear airplanes get even more cross channels

 

And now let's show how the rear fuselage is added on.  We start with four longerons built from 2024 aluminum, with an angle size of 0.875 x 0.5 x 0.063 inches.  We then add some bulkheads, a vertical stabilizer, and some rivets.  We also use gusset plates.  Since there is no welding in the rear of the fuselage, the 2024 is an excellent choice.  (You can't weld it, but good golly goodness is it strong.)  Tensile strength of the longerons is off the charts:  each longeron could lift nearly 5900 pounds.  In a few more days, I'll have some photos of the completed rear fuselage.

Rear fuselage of Belite's aluminum airplane

rear view of the rear fuselage of Belite's ultralight aircraft

front view of the fuselage, it's all coming together

Broken Flaperon Repair

We just repaired our proto aluminum airplane.  We put triplers on the root flaperon riser, and we put a doubler on the opposite end flaperon riser.  We did this on both flaperons, left and right.

The doublers were reinforced with JB Weld (cleaned and roughed surfaces first) and the extra new pin bolt is a stainless 6-32 bolt with a locknut.

In the second photo, you can faintly see the crack on the original flaperon riser.

Here's the pics:

The original failed part is in the middle of the aluminum sandwich, above.

6-32 stainless bolt with washer.

Right wing riser with reinforcements.  This one wasn't cracked.

Outboard flaperon riser with doubler.  We reinforced both outboard left and right flaperon risers.

Inboard flaperon riser with triplers, JB Weld, and bolt (which will be trimmed).

Service Bulletin: Broken Flaperon Riser

As Belite manufactures Part 103 aircraft, and also parts for experimental (customer-built) aircraft, this bulletin has no force of law.  You may choose to follow our advice, or ignore it.  We hope you follow our advice. A picture of the broken part, along with a new part is at the bottom of this post.

While inspecting our prototype aluminum airplane, one of our personnel found a broken aluminum flaperon riser on the innermost position on the flaperon.  (The position closest to the fuselage, or root of the wing, where the flaperon connects to the control cable).  Further examination determined that this was a fatigue failure.  This failure appears to have been possible where ever this part was used, and we have been using this part for some time in our entire line of aircraft.  We do not know when this failure occurred.

We have sold aircraft and kit parts with these flaperon risers.  Some were made of steel, some were made of aluminum.  We do not know which customers have steel or aluminum.

If your part is made of steel, you may ignore this directive.  We believe the steel parts are OK.

If your part is made of aluminum, we recommend that you immediately install a reinforcement before further flight.  We are in the process of designing an improved part, and also designing a reinforcement plate for existing installations.  We expect this redesign to be completed by the end of next week.  We expect replacement parts and reinforcements to be available sometime soon thereafter.

Please contact us if you believe you have affected parts, so we can advise you when reinforcement straps are available.

In the future, we will be creating a place for service bulletins on our main website.

The photo is below:

Fatigue Failure on Flaperon Riser