Wednesday, January 23, 2013

Belite Aluminum Ultralight Aircraft Cabin Construction, #9

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Let's jump right into the landing gear mounting.

Remember, you've already covered the cabin with Dacron fabric.  Also, we've chosen to pre-finish our cabin with vinyl Oracal.

The landing gear hinges are provided with our kits.  They are attached using two AN4 bolts and locknuts.  The landing gear A frames are positioned using aluminum bushing material, and each hinge is positioned over the appropriate cross box.  You will almost certainly have to grind the steel landing gear A frames to fit within the hinges.  See the photos below:

The only 'trick' in mounting these hinges is to use a layer of 2216 adhesive under the gear, which will act as a pressure gasket from the hinges to the cabin.

Landing gear hinges, bushes, bolts

Another view of a landing gear hinge.

A third view of a landing gear hinge.

The flaperon handle needs to be mounted.  A flaperon attachment plate is used on the far end of the pin which supports the handle, and the plate looks like this:

Flaperon handle attachment plate.

The plate is mounted to the cross box using a short 2" piece of aluminum angle.  A piece of angle was chosen over a simple 90 degree bend in this plate, in order to eliminate the possibility of fatigue failure at the bend.

After the angle is riveted to the plate, the plate is in turn riveted to the underseat cross box.

Angle riveted to plate.

Nylon bushing inserted into plate.

A good photo helps visualize the relationship between this plate and the flaperon handle:

Flaperon handle with steel pin and aluminum bushings over steel pin.

Another view of flaperon handle.
You'll need the ratchet plate.

Ratchet plate.
You'll need two lengths of aluminum angle:  one is the top side and the other connects the plate to the cross box.

Ratchet plate clecoed to angle.
Install the flaperon bellcrank.  It floats on a steel pin, and uses nylon 3/8" bushings.  The pin can't drop out of the bottom; and it is just long enough to be flush with the top square tube.  A bushing sits on both sides of the bellcrank.

Flaperon bellcrank.
Gusset and ratchet plate (you already know what the ratchet plate is!)
 The bellcrank lines up dead center to the flaperon handle throw arm center.  The gusset plate is used to secure the angle aluminum.

Flaperon bellcrank and flaperon handle, with throw arm.

Closeup of gusset.
Another view of gusset and flaperon handle assembly.
(capitalized letters on purpose... to get your attention; yes I am yelling at you!):

1)  Add threaded extensions (10/32 thread) to ensure that at zero flaps the full range of flaperon motion is realized.  If you don't have any extensions, give us a call and we will provide them at no charge.

2)  At 3 notches of flaps, you will have limited flaperon range left to right.  Work to have as much as possible, while preserving full range at zero notches.

3)  This is why we don't recommend flying with 3 notches of flaps -- the limited range of flaperon (aileron) motion.  We do it only to reduce stall speed for Part 103 requirements.

4)  Also note that at full left or right flaperon, the flaperon bellcrank may 'hit' the clevis -- you'll need to relieve the bellcrank with a grinder to prevent interference.  If you fail to do this, the flaperon cables will certainly fail as they are forced to bend, and an accident or death may result.

Flaperon cables and extensions
This is an excellent time for a series of photographs on the control stick and flaperon assembly.

Control stick and flaperon assembly detail.

Flaperon bellcrank, flaperon cables and extensions.

Flaperon pivot.  Note cotter key securing assembly!

Flaperon handle assembly.

Flaperon bellcrank.

Another view of exetension and handle with flaps fully extended.

Flaps fully retracted (zero flaps).

Control stick pivot assembly.

Flaperons in full left turn with 3 notches of flaps.
 Let's switch focus to the baggage compartments.  The front and rear baggage compartment are reinforced with aluminum straps:

Aluminum straps.
We'll also use some gussets:

Gussets for baggage compartment dividers
The aluminum straps are clecoed to the baggage compartment dividers, front and rear, along with the gussets:

Strap on baggage compartment divider with gussets

Another view

View of rear baggage compartment with strap and gussets

Another view of rear baggage compartment 

View of all three baggage comparment dividers (seat in middle)
 You may have noticed that a 'seat' appeared in the above photos.  It is constructed from the seat plate, two doubled gussets, a strap, and three pieces of angle aluminum.

Seat from bottom view, with each side bent.  Strap is clecoed in position.  Middle aluminum angle riveted in.
Seat from top showing gusset.

Two small angle aluminum reinforcements added.
Finished seat.
Another view of finished seat.
I have designed this airplane so that it can be flown with only this miniature seat, for purposes of saving weight for Part 103 compliance.  It is very strong, and is reasonably comfortable, especially if you have a small butt :-) and/or a seat cushion.  A full size seat is also included with the kit, and is placed on top of this small seat for purposes of normal flight for real human beings.

We are closing in on being done with the cabin.

1 comment:

Lifting Chains said...

Nice and helpful tutorials.