31% Extra 260 - Building from scratch

[RMaia]

After a long planning process I'm finally ready to start the build! This project began in January of this year, when I decided to design and build my own gasser, inspired mostly by Mike Chandley and Bob Sawyer builds.

Last week I finally finished the CAD drawings and off to the laser cutter they went. Today I just picked up the laser cut parts. I'm like a child at Christmas!

To make the construction as simple and pleasing as possible, I've made an effort to have all major parts laser cut, except the balsa sticks and sheeting. Everything else is supposed to be laser cut. It resulted in a lot of CAD work, but it should pay off now during the build, as well as after it's done, I love the look of an intricate laser cut structure.

The plane will also be entirely built-up from balsa and ply, except of course for the engine cowl and canopy.

So, here are two rendering shots from the CAD structure.

[maeu2003]

Looks awesome... I'll be following along...

[RMaia]

Continuing, here are some photos of the laser cut parts themselves, as well as of the cowl and canopy (which I didn't make by myself, working with fiberglass is a skill I have yet to acquire). The ruler in the cowl and canopy picture is 20" long, so you can have an idea of the size.

If I haven't missed the count somewhere, there are 243 laser cut parts in total (!!). The photos below show all the balsa sheets with laser cut parts. The parts will go into the tail feathers (horiztonal and vertical stabs) as well as the wings.

Each sheet is only 18" long due to the limitation of the laser cutting machine, which doesn't have a cutting area that will fit full length (36") balsa sheets.

[RMaia]

Now pictures of the Lite Ply sheets, there's a total of 14 of them, all 1/8" x 12" x 24". They contain mostly the fuselage parts, but some parts for the wing and tail feathers are of Lite Ply as well.

First two images is a general view of them and the other images are more detailed and closer pictures.

If all goes as planned, I should have more pictures by Friday, which is when I plan to really commence the build. Tomorrow I still need to get the plans plotted, and then all will be set.

[boss351]

Suscribed!

[airborneSGT]

What CAD program are you using?

[Wild Thang]

Awesome!

[Boogie]

Rhinoceros Rules!!

[jbdesigns]

Ah, this is great, really really great Rmaia. i was hooked onto this thread before i read even one word of your postings. because you put the word SCRATCH in the title. i just love it when someone builds from a kit and especially when from scratch.

i am real excited to see how this turns out.

I do have some early questions.
did you have to layout how the parts fit onto the wood sheets or did the cutter do that?
I suppose you supply the wood so you can hand pick it, correct?
can you give us the cost for cutting this kit?
i am guessing you are to use 50cc motor. do you think you will obtain sub 15 pound final weight?
do you have plans/ideas on how you will build up the wings and tail parts? i don't know if you built tabs on the ribs or not to help with that. i am sure you will let us know in due time how you will build that.
oh, what cowl and canopy will you use or are you going to have to make those?

i so wish you good luck and success.

John

[RMaia]

Thanks for the kind words!!

About the CAD program, Boogie got it right, it's indeed Rhinoceros (sometimes also known as Rhino 3D). I like it a lot, it's not difficult to learn (I learned it by myself) and quite powerful.

Things are progressing, today I got the plans plotted, so tomorrow I'll be able to take the first steps in the build.

[RMaia]

	Quote: Originally Posted by jbdesigns
	Ah, this is great, really really great Rmaia. i was hooked onto this thread before i read even one word of your postings. because you put the word SCRATCH in the title. i just love it when someone builds from a kit and especially when from scratch. i am real excited to see how this turns out. I do have some early questions. did you have to layout how the parts fit onto the wood sheets or did the cutter do that? I suppose you supply the wood so you can hand pick it, correct? can you give us the cost for cutting this kit? i am guessing you are to use 50cc motor. do you think you will obtain sub 15 pound final weight? do you have plans/ideas on how you will build up the wings and tail parts? i don't know if you built tabs on the ribs or not to help with that. i am sure you will let us know in due time how you will build that. oh, what cowl and canopy will you use or are you going to have to make those? i so wish you good luck and success. John

Thank you!!

The parts layout was made by me, I just supplied the wood (yep, hand picked) and the cutting files (in DXF format) to the cutter. The total laser cutting fee for these parts was about $100. And there's about $150 worth of wood (just for the laser cut parts, not counting the sheets and sticks yet). These values are converted to US dollars from what I paid here in Brazil in our local currency, though, so I believe in the US the cost would probably be slightly lower. The total cost for the whole kit I don't know yet, as I still have to figure out how much wood will be used for the sheeting and so forth. But I'm keeping track of it, so in the end I'll be able to tally up the total.

Yes, the engine will be a DA-50. The weight target is actually slightly higher, I'm shooting for 18 lbs or less. Actually, 17 lbs would be sweet. I'm pushing a little the size threshold for a 50cc engine here, so I'm expecting a bit higher weight. The span will be 94" and the fuse length (not counting the spinner) will be 82" (I tried to keep it within the 10% scale rule). But if it comes at 16lbs or less, then I'll be very very happy! Let's see how it will turn out, the intention is to have it as light as reasonably possible.

Yep, the tabs on the ribs are for building. They're already with lengths set to the correct height of each rib, be it on the tail or on the wings. All that's needed is a flat building surface to ensure the proper alignment. Some care while building as well...hehe
When I get there, the photos should indeed help to give you a better idea.

[RMaia]

Today I ended up busy for most of day, so I wasn't able to do much progress, but I did get started!

I removed from the ply sheets all the parts for building the motor box, and made a dry fit of all of them. All the work in designing the interlocking tabs payed off! The assembly was very quick, and all seems perfectly aligned. Two parts had slight errors in the placement of the tabs, nothing major though, a little bit of sanding and then they fit (I took the pictures below before sanding those parts, so they're not in the pictured assembly).

Tomorrow I'll remove all the lightening hole's "covers" and then do the final gluing. I also need to cut tomorrow the motor mount out of 1/4" Birch Ply. That's the only major part I didn't have laser cut due to cutter not having the power required to cut 1/4" Birch. The template was laser cut out of 1/8" Lite Ply, though, so it shouldn't be too difficult.