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Plans for 3.14

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Old 10-12-2006, 02:16 PM
  #1
bbt
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Default Plans for 3.14

Hi,

For some time I had a a large a large 3D plane on my wish list ... the design and plans are on their way.

It will look like the OMP Edge 540 Hybrid.

The design is based on the following idea: when watching the proportions and dimensions of most of the 3D planes, I realized that 1/3 looks like a constant. Well ... I select the most mysterious constant ... Pi or 3.1415. This constant was/is fascinating generations of scientist and the final value of Pi is still undiscovered.

Based on Pi, I calculated most of the plane dimensions (eg: root chord = Fuse length * 31.4%, CG of wing place at 31.4% of the fuse length, aileron width = 31.4 % of the chord, ...).

I know this is a very empiric way to design a plane but it worked very well! The plane name was fairly easy to choose

The plans and laser cut sheets will be available soon for the following wingspan:
- 153.8 cm (60.5 inch) / 70 class motor or Hacker A50 powered by 5-6 LiPo
- 205 cm (80.7 inch) / 50cc Gas motor

As usual, I'll share the plans with you guys. Expect the same plan quality as for the Spirit of Pitts. Watch this thread.

Cheers,
BB

Work is still in progress but here is a first preview:
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Old 10-12-2006, 04:49 PM
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Default RE: Plans for 3.14

Sweet! Next, phi=1/phi as a base. Wait, is that too geeky? Can't wait for the progress, BB.

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Old 10-14-2006, 02:22 AM
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Default RE: Plans for 3.14

I am progressing. Slower that expected because I am loosing a lot of time to input the Pi value in my calculator.
Here is the precision I am using for my project: [link=http://3.141592653589793238462643383279502884197169399375 105820974944592.jp/]3.14[/link]
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Old 10-15-2006, 04:15 AM
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Default RE: Plans for 3.14

You will find below a snapshot of my drawing board. It is still a bit messy: the layout still need to be worked out as well as some details.

Some design features:
- The fuse is designed to be extremely rigid
- Wing airfoil : E168 (14%)
- Two piece wing (w/wing tube)
- Three positions for the wing tube on the fuse for optimal plane balance for various motor configurations.
- Airfoiled elevator and rudder (NACA0008)
- Motor mount for conventional or electro motor

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Old 01-02-2007, 04:41 PM
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Default RE: Plans for 3.14

The plans are now finished. I am quite happy with the results and confident this will fly like hell.
The next steps are laser cut and find time for the build.

Here are again a snapshot of the plans and the laser cut sheets:
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Old 01-02-2007, 08:36 PM
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Default RE: Plans for 3.14

Took a look at your files for cutting.

The ribs I think are too thick at 3mm plywood. Consider 2mm plywood. Here I have been using 2mm balsa with 1.5mm reinforcements at landing gear mounts.

Many-many parts could be connected to one another. Those with straight side could be butted up against another with straight side, allowing the laser to cut one line for two parts.

The locking tab gap on plywood parts is too big. Make only about .030 to .040" gap. Use only two gaps per part, and one gap to lock in an internal, or cut out section. Birch plywood will easily hold together better than balsa. So go to fewer and smaller gaps.

Get rid of the acute angle cut areas. Put a small radaii fillet in instead, or you will get little extra burn mark, and not get same strength.

As to slots for interlocking parts. Do not make same size. Instead purposely cause an interference fit by about one diameter of laser light.


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Old 01-03-2007, 03:38 PM
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Default RE: Plans for 3.14

CoosBayLumber,

The weight gain by changing the rib plywood thickness from 3mm to 2mm will require some interlock rework and the weight gain will be marginal. Therefore, I will keep it as is.

You are indeed right. Using one laser cut line for two parts will decrease the laser cut cost. I will re-work the laser cut sheet to apply this principle where possible.

The excessive burning will only happen where the angle is very sharp (below 25-30°) and/or in tick material like 5 ply plywood 1/4 inch or similar. I didn't notice excessive burning in 3mm birch plywood so far. I guess that a laser correctly calibrated for the material to cut was also contributing to this. My preferred laser cut supplier is dealing beautifully with this

I already took care of the laser cut kerf for the interlocks. In very thick materials where a lot of heat is generated, the kerf can be -worst case- 0.030". In thinner materials, the heat generated is lower and the kerf is down around 0.005". The 1/4" balsa or 1/8" birch plywood has a kerf between 0.010" and 0.015" depending on the density of the wood. In this case, the kerf is compensated by 0.010" offset.

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