Volksplane 21 Highwing, Wood, CNC

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FritzW

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This is a spin off of the 21st. Century Volksplane thread. The idea is to start getting an idea down on (electronic) paper, flesh out some details and see if an airplane like this is feasible.

This would be a VP-21HWC Mk-I (1st pass at a highwing, wood, all CNC cut, super quick build, open source). The goal would be that a guy could (free) download the G Code, get some wood and take everything down to his local CNC shop and have a kit cut out. He could also just buy a kit from anyone who wanted to make them. This would be really handy for guys who have a CNC machine in the garage (there are more and more of them every day).

Ideally, but probably not practically, all the builder would need would be a bottle of glue and some clamps. All the parts would be CNC'd, even the 'sticks'. And any parts that didn't have some sort of tab and slot would be pre-drilled for alignment pins (1/8" Nylon bolts) that hold the parts in position until the glue dries.

HWC.jpg LOTS of stuff still to draw. It's still more of a "build process/method" study at this point.

HWC 2.jpg Some of the ply is set to "transparent" to show the innards

HWC alt rudder2.jpg HWC alt rudder3.jpg Maybe a regular VP-1 or VP-3 rudder, or maybe this one.
*I just realized I hooked up the antiservo tab backwards in this model (SolidWorks Mates), hope I don't do that on the real thing :shock:

1429139787.jpg I made a spar for that rudder just for grins. It was very simple but could be lighter.

...I've got a nice "new and improved" VP-1 stab model somewhere but I can't find it:/

HWC CM.jpg I don't know if this is a good idea or not, but I really like the modular assembly idea. I'm trying to come up with "modules" that could be built on the kitchen table. You wouldn't need a garage until it was time to assemble the modules.

HWC Strut Carry Through.jpg HWC Strut Carry Through EXP.jpg Even the modules are made out of modules :gig:

The process.jpg I made a spar carry through ...just for grins, a looong time ago when I was still trying to build airplanes with a Carvewright machine (small CNC machine that looks like a big planer)
 
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FritzW

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(cont)
HWC CM2 seat.jpg HWC CM3 seat.jpg it looks like a mess but it would go together in about an hour.

HWC rail pins.jpg HWC alignment pins.jpg here's how the 1/8" Nylon bolts would work

It's an Open Source idea, all comments are welcome. ...if I can figure out to post files on the HBA everybody is welcome to the files.
 
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TFF

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It works better as a high wing. Go for a 2 seater that can be flown in the center as a single like the Sonex. If it comes out it will be what everyone wants except not going 400kts.
 

Mooney

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Very cool idea and I like where you are going with this.
I'll be following along with this thread.
 

Autodidact

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This is almost as cool as an actual build! It's faster (or can be...) and there's plenty of problem solving, technology demonstrating, conceptualizing - cool!

Edit - this is a great idea, how come no one's done it before? Have they? Download "G-code" (and instruction pdf), run parts, glue and clamps, voy la - an airplane!
 

nickec

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Because CNC machine time competes with other work, the economy of ordering a run at a CNC shop is questionable.

If you already have a CNC machine large enough you need to account for the costs in time and money to own the machine.

The actual set up time and cutting time will be significant which puts into question the "quick build" aspect.

Companies which own CNC machines invest in them when the economics makes sense. When they can profit from them.
 

FritzW

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Ref: Cost of CNC'ing an airplane like this.

We've covered this pretty thoroughly on the VP-21 thread. An airplane like this would take less than 500 minutes to cut, probably a lot less (at a buck a minute). There are lots of garage CNC hobbyist' that would cut these out all day long for $500, including me:)

I also think that home CNC machines are going to be as common as table saws before long. Might as well have a CNC airplane ready to go.
 

FritzW

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Ref: 2 seat SBS

That's the smarter choice but I figure it's easier to work out the details on a simple one holer.
 

Pops

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As most of you know, there is a lot more in designing a two seat than just making room for the extra person. I say stick with the single seat until its a success and then when you want something to do, work on the two seat version.

When I get the JMR SPecial flying I am going to build a aluminum set of wings, and after that is finished I plan on making a two seat version. But it making it a two seat, its really a new design in keeping the same performance as the single seat.
At my age, I hope I don't run out of years :)
 

12notes

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Because CNC machine time competes with other work, the economy of ordering a run at a CNC shop is questionable.

If you already have a CNC machine large enough you need to account for the costs in time and money to own the machine.

The actual set up time and cutting time will be significant which puts into question the "quick build" aspect.

Companies which own CNC machines invest in them when the economics makes sense. When they can profit from them.
This may have been true in the past, but CNC machines are a lot more common and affordable now. Here in Louisville, Kentucky, I (and everybody else) have access to at least 6 that will do wood of various sizes, 1 of which is large enough for full sheets, and a second that is large enough to half sheets. They are free to use for personal projects. 3 are at the LVL1 hackerspace, and 3 (including the 4x8 one) are at FirstBuild, a GE-run hackerspace. It's not that difficult to build your own either, nor is it outrageously expensive (sub $1000).
 

Tiger Tim

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I like the ideas going into your VP-21 concept but I have to say I'm a little surprised to see it's a parasol. Do you have any thoughts on how to make the cabane structure as builder-friendly as the rest of the plane?
 

FritzW

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I like the ideas going into your VP-21 concept but I have to say I'm a little surprised to see it's a parasol. Do you have any thoughts on how to make the cabane structure as builder-friendly as the rest of the plane?
It started out as a -doors optional- cabin airplane with a welded 4130 birdcage bolted to the tabs you can just see in the second picture. Now I'm trying to figure out a "hacksaw and drillpress only" set of cabanes, something like a Corben Baby Ace but all bolt together, no welding. ...the jury is still out;)
 

Victor Bravo

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If you can compress all the specialized fabrication and welding into one part, then it's probably not a deal breaker IMHO. If there is one front and one rear welded cabane assembly (identical to each other, hint, hint) that's not a huge inconvenience or cost spike. If you can do 95% of the structure with glue and bolts and screws, and you need these two welded steel parts, then it's probably a couple of hundred bucks for the flight-critical parts.

But when an airplane needs the struts welded up, and the landing gear welded up, and the engine mount, and the spar fittings, and the control system, and the rudder pedals all welded, and a hundred little brackets for pulleys, and welded bellcranks.... and it becomes a couple of thousand bucks for all that if the guy is not a welder... then you may arrive at a "pain point" that keeps some potential people away.

So to me, THAT is one of the big 21st Century breakthrough things that will greatly simplify the airplane.
 

Riggerrob

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It started out as a -doors optional- cabin airplane with a welded 4130 birdcage bolted to the tabs you can just see in the second picture. Now I'm trying to figure out a "hacksaw and drillpress only" set of cabanes, something like a Corben Baby Ace but all bolt together, no welding. ...the jury is still out;)
...................................................

May I suggest a set of fancy, CNC cut blocks. The CNC machine would also drill a series of holes through the blocks. Some holes would be big enough to accept structural steel tubes, while other holes would only be big enough to accept the bolts that "pin" the cabane struts together.
An automotive engineer might be able to press similar fittings out of sheet steel, but not many home builders have that large a hydraulic press and even fewer are willing to invest in the dies.
Hah!
Hah!
Maybe we will have to wait another 5 years until the CNC blacksmith is perfected!
More laughter!!!!!!
 

Rienk

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Maybe we will have to wait another 5 years until the CNC blacksmith is perfected!
More laughter!!!!!!
Here's your CNC blacksmith - wonder what this would set you back...

[video=youtube;s9IdZ2pI5dA]https://www.youtube.com/watch?v=s9IdZ2pI5dA[/video]
 
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Rienk

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If you can compress all the specialized fabrication and welding into one part, then it's probably not a deal breaker IMHO. If there is one front and one rear welded cabane assembly (identical to each other, hint, hint) that's not a huge inconvenience or cost spike. If you can do 95% of the structure with glue and bolts and screws, and you need these two welded steel parts, then it's probably a couple of hundred bucks for the flight-critical parts.

But when an airplane needs the struts welded up, and the landing gear welded up, and the engine mount, and the spar fittings, and the control system, and the rudder pedals all welded, and a hundred little brackets for pulleys, and welded bellcranks.... and it becomes a couple of thousand bucks for all that if the guy is not a welder... then you may arrive at a "pain point" that keeps some potential people away.

So to me, THAT is one of the big 21st Century breakthrough things that will greatly simplify the airplane.
Beside designing for CNC, the other key component is designing around OTS (off the shelf) parts.
When designing the TS-1, everything was based on making 2D parts that interlocked or assembled as needed (and yes, there can be a weight penalty to that). Anything that couldn't be made this way needed to be an "inexpensive" Aircraft Spruce (or similar) part.
This is all possible now.
The reality is that there are a lot of potential builders who have very little capability, and will need to buy kits/assemblies/parts from others... but there's no reason that a cottage industry can't build up around a handful of popular designs - and hopefully not make it so expensive that the low-cost, quick-build objective is lost.
 

FritzW

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Here's a low cost option for a small CNC machine. I poked fun at it back in post #1 but I've actually made a bunch of airplane stuff with it. It's better suited to making fancy furniture but it's got possibilities.

I used it to make a "proof of concept" model for another project.

2012-03-08 16 48 24 (2).jpg 2012-03-08 21 47 01.jpg IMG_2481.jpg The idea was to make assembly jigs and templates for a hand router.

IMG_2483.jpg IMG_2489.jpg I found an easier way to do it so this idea and the Carvewright machine went on a shelf.

2012-03-08 21 47 16.jpg IMG_2496.jpg The spar were "built in place" in the wing, impossible to screw up the alignment. I may try this again for the VP-21HWC Mk-I. Two days into the project and I'm already loosing focus :gig:
 

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