The XPB Stage 1 underway.

[bexrbetter]

And we'll need a Dorsal Fin and VS as well, which all fits nicely onto a sheet ...

 

[Marty_d]

Are your skins the same thickness as your spars?

 

 

[bexrbetter]

Are your skins the same thickness as your spars?

 

For the rudder ribs (not spars)? Yes. Where possible it is only one thickness throughout the entire plane

 

Or did you mean other? 0.5mm might be a bit light for the wing spars, but I'm happy for you to try it.

 

 

[bexrbetter]

And we'll need a HS and spars too ..

 

I won't draw the skins up until I laser and fold the spars, and assemble with the ribs to get accurate measurements.

 

 

 

[bexrbetter]

Man, been putting some hours in, seen sunrise a couple of times.

 

I nested the entire Rear Fuse, HS and VS, then I virtually built the entire assembly again in the software to find the small fitting issues, and there were some, mostly rivet holes not lining up, couple of part sizes not change or moved (or not) at some stages.. And when I say build, starting with flat sheets as if they had just been cut. I folded and fitted them all together piece by piece then modified them if required, transposed to flat sheet, fold again and repeat.

 

There's also the one that used to catch me out  a few times years back, and that's creating stuff in 3D as flat material not allowing for the thickness of the material in the real world, and over a few parts, that error can build up quite quickly.

 

So now tonight I celebrate my first sheet of 6 for the  in .DXF file ready to go to the laser and fold shop early next week. I tried hard to fit everything onto 5 sheets, but just couldn't, dang narn it!

 

 

 

[bexrbetter]

Oh, and have a name for the plane at the moment.

 

It was a tough one, but I took in the considerations of my Sino -Australia relationship and America being the key market, the plane type, specs, mission suitable for ect and eventually I came up with the perfect fit ...

 

"Bob".

 

.

 

 

[kgwilson]

Won't be hard to remember. It is even the same if you say it backwards.

 

 

[onetrack]

What was wrong with the name, "Glorious New Golden Treasure Flight Product of Chairman Mao's Red East?" 

 

You could have even have the name plates produced with "Gloroius New Golden Treasere Flight Porduct of Chairman Mao's Red East?", to give it real authenticity. 

 

 

[pmccarthy]

That doesn’t work as an acronym. At least BOB could be built of bits, or bag of bolts.

 

 

[Old Koreelah]

Bec I haven't been following this project closely, so may have missed this point. It occurs to me that you're trying to get the max. number of component parts out of each al. sheet.

 

Lots of brainwork, but I believe software exists that can rearrange 2-D shapes to minimise wastage.

 

I guess then there would have to be a trade-off between optimum component shape and minimising waste of material.

 

 

[onetrack]

Old K, this is the go-to product for fabricators ... http://www.optinest.com/

 

 

[Raytol]

Hi Bex,

 

I love what you are doing on the computer but you don't seem to be allowing for the"grain" direction in the sheets of material. Aluminium sheets are rolled to thickness

 

and so they are not really a homogeneous ( could not think of the correct term!) material. In "Alclad" sheets this is hidden by the pure aluminium coating but you can

 

see it more clearly on the 6061-T6 sheets. It is much easier to crack aluminium bending it across the grain than with it and it also affects fatigue life.

 

It will probably mean having to buy more sheets of material!

 

When you do your parts for bending you will need to have a "bending allowance" which in most cases gains you material. Also you will need to supply the bending

 

shop with a line to line up their blade for bending ( different if done on a bender or brake press). The bend radius is determined by the thickness of the material.

 

All this information is available in " The Aircraftsman Handbook" or in AC-43.

 

Ray

 

 

[bexrbetter]

When you do your parts for bending you will need to have a "bending allowance" which in most cases gains you material. Also you will need to supply the bending

 

shop with a line to line up their blade for bending ( different if done on a bender or brake press). The bend radius is determined by the thickness of the material.

 

All this information is available in " The Aircraftsman Handbook" or in AC-43.

 

Ray

 

My bend radius is around 4T so grain isn't an issue.

 

All my sheets have alignment tits or other for the bend shop to line up, saves a lot of time and is very accurate, as indicated in red below

 

Later when my tits are cut off (wait, what?), a relief corner radius is left, as is in the corner of the inverted V bend point.

 

[bexrbetter]

Bec I haven't been following this project closely

 

 

 

Non-believer!

 

Heresy, damnation for you!!

 

 

Lots of brainwork, but I believe software exists that can rearrange 2-D shapes to minimise wastage.

 

I guess then there would have to be a trade-off between optimum component shape and minimising waste of material.

 

 

 

I actually enjoy it, find the puzzle solving a bit of fun. Strange, because I have always disliked jigsaw puzzles.

 

However, I haven't looked for a few years and noticed a couple of free ones out there, so going to try them and see if they can do better than what I already have.

 

 

[bexrbetter]

What was wrong with the name, "Glorious New Golden Treasure Flight Product of Chairman Mao's Red East?" 

 

You could have even have the name plates produced with "Gloroius New Golden Treasere Flight Porduct of Chairman Mao's Red East?", to give it real authenticity. 

 

 

 

 

 

 

 

[bexrbetter]

Almost saw sunrise this morning, but worth it because all CNC Laser files finished (for the rear fuselage stage), and 6 sheets dropped into the Laser shop with the file, should see some parts late tomorrow or Wednesday.

 

My biggest headache today was getting the protective plastic film off the 6 sheets, damn they don't make life easy!

 

Old K, this is the go-to product for fabricators ... http://www.optinest.com/

 

 

 

I tried a free open-source one called Deepnest, let it run for a hour and it was just coming up with stupid results.

 

My method is very simple, I put the biggest parts possible onto a sheet (importantly I design the parts so they can fit onto a 1200 x 2400 sheet in the first place), then try to fit the second biggest part on, if not, then the third biggest and so on. 

 

I can't understand why this stupid software doesn't do that and start with the biggest parts first?

 

Here's mine.....

 

 

.. what I gave to the software to test ..

 

 

... and it's best offering after an hour ..

 

 

 

[bexrbetter]

Here's maybe a helpful tip for those interested.

 

You see the 4 long rectangular parts that compromise 13 separate parts end to end, and the 8 pyramids at the bottom (that just fit onto the sheet) to be lasered ...

 

 

Well the reason they are joined like that instead of individual parts is for accuracy in the folding that they will receive later. Folds are done in a brake press and the longer the part, the less percentage of error over the length.

 

So each long rectangle, and those 8 pyramids, will be folded together as one piece, then cut apart with the snips, and all the parts will be very close to being identical.  

 

Oh, and the pyramids (gussets) are flipped every 2nd one so i get left and right hand parts automatically after folding.

 

 

[Old Koreelah]

Bex I guess your al. sheet cutting-out isn't much different to what most of us have done with gyprock, hardi flex, plywood or cotton fabric.

 

We might be better off without the wizz bang software; getting a perfect job done is one objective, but (especially for those of us trying to postpone dementia) giving our onboard computer a good workout is still important.

 

 

[Old Koreelah]

...My biggest headache today was getting the protective plastic film off the 6 sheets, damn they don't make life easy!

 

Bex you probably already know this but I've learned to remove that film ASAP, even if I plan to store a sheet for years. I suspect UV helps to "cook" its adhesive onto the surface.

 

 

[bexrbetter]

Bex you probably already know this but I've learned to remove that film ASAP, even if I plan to store a sheet for years. I suspect UV helps to "cook" its adhesive onto the surface.

 

Yup, have had the misfortune to have to remove 'old' plastic before that once you get the bulk of it off, you're left with lots of thumb sized bits you need to remove one by one picking at with your fingernails. Drives you crazy.

 

 

[Marty_d]

I was glad mine didn't come with plastic coating.  Just came bare, separated with brown paper.  Made things easier.

 

 

[Kyle Communications]

I had the same with some of the sheets I got for Mabel...I found "cleaning vinegar" was the best surprisingly. I tried every kind of solvent just about known to man and no or little success. The best was the vinegar left overnight kept wet by rags full of it sitting on the sheets then the next day or 2 later hit it with the karcher high pressure sprayer..got 95% of it off..the rest was elbow grease....NEVER again will I buy older plastic coated alu sheet

 

It took weeks to clean them

 

 

[Litespeed]

 And thats the bitch of it. A prick to remove but if you want unmarked sheets it is generally all that is  available.

 

Then you get to scratch it removing it.

 

But storage is the bugger unwrapped as well. Have not had paper supplied ones. I bet a paper coated one would be best and easiest to remove. To have to resort to soaking, vingear etc is ridiculous in 2019.

 

Its not like the bloody stuff is cheap or anything.

 

Rant over.

 

 

[bexrbetter]

So Guys, let me introduce to "Bob".

 

Bob is as simple a plane I could figure from all my experiments and investigations over the last number of years.

 

Simplicity, cheap to produce, cheap and very fast to build while encompassing strength and safety.

 

... and it's wide! Australians and Americans have grown somewhat over the decades, many plane manufacturers just don't seem to have kept up with that fact.

 

One unusual feature with Bob is the staggered cabin to give real world shoulder and arm room to the Pilot and Pax, no more of the upper body 'twist' to avoid rubbing shoulders with your smelly Buddy on the way to grab a hamburger, and somewhere to actually rest your arm.

 

A further bonus is that the stagger is made up of just 4 components, the armrest, the rear fairing, a small filler panel behind your shoulder, and of course the canopy - all 3 components can be widened or narrowed to suit the owner with considerable ease, either during the build or modified later on.

 

... but it's also just plain wide. The inside is the magic 1 meter, or 39.5", and the shoulder room is over 1200mm or 48".

 

As you have seen, I build what I show, the complete rear fuselage, VS and HS parts have all been cut and waiting for me to get there, and get them to the fold shop.

 

Assembly should start in a few days!

 

 

 

 

 

 

 

 

 

[onetrack]

I'm staggered no-one has thought of this before.