Wednesday, April 25, 2012

Fuel Sender Installation in Plastic Tank

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Here's a quick way to get a fuel sender into any ultralight aircraft.  We've done this with aluminum tanks, by welding a 'platform' onto the tank for the fuel sender, but it's quick and easy with an inexpensive 5 gallon tank from Walmart.

Here's how.  Start with a fuel sender, which you can purchase from us or from Aircraft Spruce, which looks like this:

Fuel Sender

The fuel sender has three connections:  power, ground (+12v), and fuel sender output (provides 0 to 5v to fuel gauge.)

Of course, you'll need a fuel gauge.  Many different companies sell them.  Ours features brilliant adjustable daylight readable LEDs, and minimal power consumption, and absolute lowest weight (less than one ounce).  It looks like this:

fuel gauge from Belite


and it fits in any standard 2 1/4 inch instrument hole.  All you need to do is attach ground, power, and attach the input to the fuel sender.  (Use a 1 amp fuse when running power to the fuel gauge and the fuel sender.)

We also use a classic red 5 gallon tank from Walmart, and we drill a hole in the top for the fuel sender.  (We also drill a hole for the fuel line 'bobber' to feed through.)  The tank must be vented, and the 'slop' around the fuel line hole provides this venting.

It looks like this:

Fuel tank for ultralight with fuel sender hole drilled out.

We then place the fuel sender through the hole below the handle, and secure using five ordinary wood or deck screws.  We don't use nuts/bolts, because they are way too hard to get the nuts into the tank.  The gray material is a fuel tank sealer, which merely provides a gasket around the hole, to prevent fuel from sloshing out.  You can get it at your hardware store.

One of the neat things about using this kind of tank is that if you use a quick release fitting on the fuel hose, you can swap one fuel tank for another in your ultralight airplane.

After installation, follow instructions with the fuel probe for setting the empty and full positions on the gauge.




Sunday, April 22, 2012

How to assemble a truss structure rear fuselage on an Ultralight Aircraft

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Assembly of a rear truss structure aluminum fuselage for a
Belite Ultralight Aircraft

It’s easy to assembly a rear fuselage for a Belite ultralight airplane!


1.  PARTS INVENTORY CHECK

Your kit should have the following items in it:

A)    Pre-riveted frames, constructed from 2024T3 aluminum, 7/8” x ½” x .063”.
B)     Longerons, with tabs already attached.  Also constructed from 2024T3 aluminum.
C)     Rear post, with pre-welded rudder hinge point. 
D)    Gussets.  Gussets are made from either .032 or .040 aluminum, 2024T3 or 6061T6.
E)     Truss pieces, constructed from 2024T3 aluminum.
F)      Rivets – commercial grade.  If you are interested in using aircraft grade rivets, we encourage you to purchase them directly from Aircraft Spruce, or the supplier of your choice.  We do not supply them.
G)    Top skin aluminum, pre-routed. 

Here is the pictures of the parts:

Section Frames, Six of them, A through F.
The frames are ‘A’ through ‘F’ as shown on the blueprings.  Each is riveted together.  All are easy to identify by comparison to the blueprints, with one exception:  One of these frames has a dimension of 19 by 19 1/8”.  Don’t confuse the vertical dimension with the horizontal dimension on this one frame; look carefully at your blueprints.


Longerons with gussets.
 The longerons come pre-riveted with gussets.

Truss sections.
 The truss sections are all labeled as shown.  You may also notice color coding, which we do to help you sort out where the truss and frames rivet together.

Rear post.

The rear post is pre-welded for rudder attachment.  DO NOT RIVET to the top of this post as it has to receive the vertical stabilizer, rivets would obstruct inserting the vertical stabilizer post.

Gussets.
 The gussets are obvious in use, especially after reviewing all photos.

*PLEASE NOTE that we are now using small triangular gussets INSTEAD of the small wrap-around gusset shown on the bottom right of this photo.*

Top skin, predrilled.
The top skin is also drilled and ready to rivet in place.



2.  WORKBENCH AND PROJECT PREPARATION.

We recommend that you prepare your absolutely flat workbench with a centerline (denoting the center of the fuselage and positions for each of the frames.  You can see these lines throughout our photos.

The fuselage is built upside down.  The top longerons are placed on the workbench; the frames are riveted in place; everything is placed absolutely dead square to the workbench (90 degrees to the table top.)  Use squares, clamps, and whatever else you need to keep it all completely square.  Measure twice and drill once.

All holes should be de-burred.  It is our experience that the 2024 aluminum alloy makes very clean holes, with very little chipping or burrs on the edges of the holes. 

We supply commercial grade rivets with the fuselage.  There is no place on the fuselage that requires aircraft grade rivets.  However, if you encounter low quality commercial grade rivets, don’t hesitate to drill them out and replace as appropriate.  (As an example, you can tell a bad rivet by a non-uniform pull force.)

The entire fuselage may be reassembled, prior to riveting, using Clecos, which we do not supply.  Having the entire fuselage in its final form may provide you with a great deal of certainty that you are doing it correctly, but this choice is up to you.   If you choose to use Clecos, your fuselage project may look like this:
Clecos in use
And here is another pictures of clecos:

More clecos in use
 Let’s get to work on putting this fuselage together.
 


3.  FUSELAGE ASSEMBLY.

Lay the top longerons and small rear gusset plate on the work bench.  (Remember, this is upside down.)
Top longerons.
Now rivet the rear plate in place.  (We recommend riveting this plate in place, even if you are using Clecos.)

Rear plate and top longerons
 Place the “A” frame in place as shown in the photo, below.  Note that a cross brace has also been placed on this A frame; make sure that the A frame is absolutely square.   The cross brace supports load from the fuel tank, which eventually rests on the cross member of the A frame.  Use any aluminum for the cross brace.

'A' frame in place, along with cross brace
Rivets at base of "A" frame
 Rivet the A frame in place.  In the photo above, you can see a typical rivet pattern in the A frame.  Our gussets are now cut on our CNC shopbot and are much ‘prettier’ than shown above.


"A" frame centered on workbench and riveted in place
Note how the center of the A frame has been centered onto the workbench centerline.  Both sides are riveted in place.

Weight placed on top of "A" frame


A weight has been placed on the A frame to keep it from moving. 

Now, place all frames in place and rivet.  Note that all frames are exactly where they need to be, and we use weights to keep them in place.  The longerons are matched exactly with the beginning of our table (barely visible in lower left corner):
A through F frames in place
Rivet holds frame to longeron
Each frame is held by a single rivet at this time.  A second rivet will be drilled and placed, later.  The gap in the frame is expected, as shown in the above photo.  And although you can’t see it in the above photo, the rear of each frame has been beveled so that it will clear the interior of the longerons.

Additional longerons are then placed along the opposite side of each frame. 

Longerons on other side of fuselage

Rivets in gussets
The rivets are placed into the new longerons and frames as well, as shown above.  Everything needs to be square and line up, as shown in the photo below.
Fuselage view down center top
Fuselage view down inside
Rear gusset
The rear gusset is used to hold the longerons in place.  Note that rivets have been used to keep the longerons together, but the rivet pattern has not yet been filled out.

NOTE:  Taildraggers use FOUR of these plates (quadrupled thickness); tricycle gear aircraft use TWO of these plates (doubled thickness).
Rear post
 The rear post is also held in place temporarily with rivets.

Another view of rear post
Small Wrap gusset
NOTE:  the gusset in the above photo has now been replaced with two triangular gussets, one on each side.  It’s much easier to fabricate. 
Large wrap gusset
The other end of the rear post will accept the vertical stabilizer.  It is notched into the longerons, then held in place with a doubled wrap around gusset.


Figure 27  Rivets on wrap around gusset


Now it’s time to start adding truss sections, starting with the rear gusset, then moving forward to other frames:
Rear post with truss added

Another truss added

All of the truss sections are added and riveted in place:
All trusses in place
And one reinforcement is added, parallel to the rear post.  It is in the photo below, immediately flush to the rear post.  Because the rear post may not be riveted, this parallel structure provides compressive strength to the rear assembly.  

Rear post with parallel reinforcement.
Typical gusset; two rivets per frame
Each frame and gusset is riveted out.  Note that each frame now has two rivets connecting it to the longerons.

Big gusset on rear post
You will also need to flip the fuselage over and add the top skin. It is possible to place without clecos, but go very slowly, line it up very carefully, and make sure every frame and centerline is square.

Top skin in place.
After riveting, it’s Done!  And ready to attach to the fuselage cabin.

The rear fuselage must be covered with fabric (after assembly to cabin) in order to have adequate strength.  Make sure you review final assembly requirements prior to covering.

Wednesday, April 18, 2012

Awesome video on Belite Aircraft

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!


Dan Johnson posted a very informative news interview of me, with several great flying clips of various Belite ultralight aircraft.  He filmed most of it at Sun N Fun a couple of weeks ago.

If you have any interest in any ultralight aircraft, including our Belite, you have to watch this video.!  Please!

Click here to see the video.



He's got some clips of all the Belite configurations, including taildragger, tricycle gear, and even our plane on floats.  He also has a lot of information on our one of a kind ultralight demonstrator, the WoW plane. 



Proof Testing an aluminum fuselage

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 my third post today!  I've already posted on CG calculations in a tricycle gear ultralight aircraft (such as our Belite), also on a Chinese ultralight aircraft which was built for less than $400.  Please rummage around my block and look at all the posts.

I made some changes to the aluminum fuselage tricycle gear design, then immediately proof tested them.  I think the results are very impressive.  You can see for yourself in the pictures.  I always enjoy seeing pictures of lightweight structures which hold many times their own weight.

Here are the three tests I made:

1.  Elevator @ 62 mph @ maximum deflection @ 150% of load calculation.  Calculation was made with flat plate area of elevator at coefficient of lift of 1 of the elevator.  According to airfoil theory, this represents maximum force when a flat plate is used as lifting surface.  (This includes many aircraft of many designs, including our 'prewelded steel elevator' option on our Belite ultralight aircraft.)

2.  Rudder @ 62 mph @ maximum deflection @ 150% of load calculation.

3.  Twisting effect of rudder on fuselage, @ 62 mph @ maximum deflection @ 150% of load calculation.

Let's look at the pictures.  First of all, the elevator deflection test:

Elevator force proof test in ultralight aircraft from Belite
The force shown here is in the weaker direction of the fuselage (down, not up.)  What you see here is 110 pounds on the end of the fuselage.  The fuselage is clamped down the bench.  My calculations showed a maximum force of 73 pounds, and so I proof tested at 110 pounds.  There was no permanent deformation of the structure.  The only part of the structure really showing the strain was the diagonal elements immediately below the weights.

Then we tested the rudder force.  This was done by placing the fuselage on the side, and adding weight.  Since the rudder is much smaller than the horizontal stabilizer, the weight is lower.  I calcuated a max force of 48 pounds, so I tested at 75 pounds.  Basically the same setup as the prior test, except the fuselage is on the side.  Here's the proof test:

Proof test of total rudder force on a Belite ultralight aircraft fuselage
And the third test was the most fun:  adding a steel rod to the rudder to demonstrate strength in rudder twisting torque.  My calculation on this showed a max force of less than 25 pounds, at a distance of 16 inches from the fuselage.  So I proof tested at 150%+, 37.5 pounds hung at at the appropriate ARM.

Proof test of rudder twisting on Belite ultralight aircraft with aluminum fuselage
You can see the actual fuselage twisting just slightly.  This wasn't a permanent deformation, just a slight accommodation which disappeared after the force was removed.

The steel bar is bending a lot.  In the actual aircraft, the rudder force is supported by the flying wires which connect the rudder to the elevator (and also the fuselage, of course...)

The purpose of all of this was to show that the strength of the fuselage is adequate, even without fabric covering.  Also, to show an alternate way to create the fuselage out of aluminum for a tricycle gear configuration.

My comments:

1.  The structure clearly had a lot of reserve.  If I wanted to increase strength, it was obvious where to add a couple of aluminum members to avoid Euler's buckling.  (Need to know more?  Go Google Euler, pronounced 'Oiler'.)

2.  I encourage customers and ultralight enthusiasts to understand these kinds of tests.  Maybe even do them on their own airplanes.

3.  The calculations were for flat plate areas of the elevator / rudder, not  the horizontal stabilizer / vertical stabilizer.

4.  Any control surface movements which the pilot initiates from the top of the green airspeed (in the yellow to the red, Vne, from 63MPH to 80MPH) must be proportionally limited by the pilot.  In other words, make slight and smooth control surface movements when you are operating in the yellow arc, just like a real airplane.  Because a Belite ultralight aircraft is a real airplane....

Here's some bonus pictures of the tests:

Looking down the fuselage of an ultralight airplane, with load applied.  There appears to be a huge reserve in the fuselage strength.

That's me!  :-)  I am also building a flaperon at the same time.  And looking distracted.

The joy of torque.

The joy of strength in a structure.

 The entire weight of the aluminum fuselage (including the cabin) in this Belite weighs about 40 pounds.