21st century Volksplane?

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cluttonfred

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On the construction method, I still believe that wood is the least intimidating material in terms of attracting first-time builders with the possible exception of aluminum tube and gusset, but that's a reflection of my own biases as much as anything else because I personally dislike working with composites and am somewhat put off by sheet metal. So my thought was to either go all wood and fabric or with a tube-and-gusset fuselage and wood wing (tail surfaces could go either way) still covered in fabric. The reason to stick with wood for the wing is that one big box spar or main and rear box spars seem like the easiest way to do a thick cantilever wing, though I suppose it would be possible to do something like a triangular truss in tube and gusset.
 

Hot Wings

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Wood may be the least intimidating material - until you pay the shipping bill and make that first cut in a piece of $35/board foot wood.
I really like working with wood, but I'll probably never again build aircraft parts using it unless I was making an accurate restoration/recreation.

Second on the intimidation chart might be tube and gusset, especially with CNC cut tubes and gussets.
 

Vigilant1

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A Cygnet redesigned to be quick and easy to built should be a winner for a 2 place VW powered airplane. Have to save all the weight you can in the design.

Added-- I had a plans built 2 place, side by side Zenith 600. ( no not a 601). Plans shows a 1835 cc, 60 HP, VW engine. Old friend of mine built it and never finished it. I got it with no engine, cowl and canopy. Gave it to my grandson along with enough parts to built a Cont-A-75 engine and went ahead and built the engine mount . Still setting in storage.
Not a hard airplane to build.
Dan, did you ever talk to anyone that had one flying? It seems to be a fairly rare airplane. Zenith had a reputation for some "optimistic" cruise speeds for their low-wing planes.
Interesting that the advertisement says you can get an "1875cc" engine with it. Probably a typo. The closest "normal" modified Type 1 displacement would be 1873cc (78.8mm stroke and 87mm cylinders) but it seems odd that someone would build a stroker and use 87mm cylinders. But, there's a lot I don't know.

Mark
 

Topaz

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On the construction method, I still believe that wood is the least intimidating material in terms of attracting first-time builders with the possible exception of aluminum tube and gusset, but that's a reflection of my own biases as much as anything else because I personally dislike working with composites and am somewhat put off by sheet metal. So my thought was to either go all wood and fabric or with a tube-and-gusset fuselage and wood wing (tail surfaces could go either way) still covered in fabric. The reason to stick with wood for the wing is that one big box spar or main and rear box spars seem like the easiest way to do a thick cantilever wing, though I suppose it would be possible to do something like a triangular truss in tube and gusset.
I love working with wood. Most people younger than us find wood to be just as intimidating as any other material, and don't like "a thousand little sticks."

And have you priced lumber (of any grade) recently?

YOU should definitely build in wood, because you like it. If the ship is a one-off for you, then case closed and on to more detailed design. If it's for commercial sale as plans or a kit, I'm not sure wood is the even the least-intimidating choice for the younger generations anymore. I suspect molded composites ("Just glue it together!") or matched-hole aluminum would get the nod by that criterion.
 

cluttonfred

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I hear you on the "thousand little sticks" and presumably that is why Evans went with plywood ribs even if they are heavier. I think that's the kind of approach you need but obviously trying to minimize any weight penalty. On the kit side, I think CNC-cut tab-and-slot plywood is very approachable. Even for a plans-built design the CNC cutting files could be included with the plans and the cutting done locally or at the very least you could offer CNC-cut templates for repetitive parts like the wing ribs.
 

Pops

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Dan, did you ever talk to anyone that had one flying? It seems to be a fairly rare airplane. Zenith had a reputation for some "optimistic" cruise speeds for their low-wing planes.
Interesting that the advertisement says you can get an "1875cc" engine with it. Probably a typo. The closest "normal" modified Type 1 displacement would be 1873cc (78.8mm stroke and 87mm cylinders) but it seems odd that someone would build a stroker and use 87mm cylinders. But, there's a lot I don't know.

Mark
I talked to a man in NC that built the 600 many years ago. He had the 1835 cc engine in his 600. Said it performed about like a C-150 when single place and like a C-150 with 2 on a warm day. My plans show a 1835cc VW engine , not a 1875 cc engine.
Stopped at Zenith factory one time and talked to Sebastian ?, he told me that 200 lb is the limit for firewall forward and no matter what you power it with, don't plan on going faster than 105 mph because of the drag.

I like wood and aluminum the best. But, wood is not the cheapest construction now. Not only the price of wood out of this world but the shipping is even worse. Believe building in aluminum now is the least costly way now.
 

bifft

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I hear you on the "thousand little sticks" and presumably that is why Evans went with plywood ribs even if they are heavier. I think that's the kind of approach you need but obviously trying to minimize any weight penalty. On the kit side, I think CNC-cut tab-and-slot plywood is very approachable. Even for a plans-built design the CNC cutting files could be included with the plans and the cutting done locally or at the very least you could offer CNC-cut templates for repetitive parts like the wing ribs.
My thought for an easy to build wing is CNC foam ribs with a thin plywood skin. Doesn't take much CNC to cut foam. Spar could be wood or composite (composite would probably be cheaper and lighter given the cost of wood today). Make the spars, CNC out the ribs, glue the ribs to the spar and then glue on the plywood. For folks who don't want to CNC foam is easy to hotwire, bandsaw or just cut by hand and sand to shape.

Quality plywood thin enough to skin the whole wing isn't cheap, but is more readily available than spar quality spruce. Use the space between the spars as the torsion box and then nail aluminum for the front for aerodynamic purposes. I see it as easy, medium cost and reasonably light, if not as light as a more optimized structure.
 

rotax618

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It would be good to know exactly which model VP we are trying to improve, VP1? or VP2?, I built a VP1 more than 1/2 a century ago, at the time it wasn't approved here in OZ, so I built it outside of the system, not having to comply with bureaucracy I modified it to suit whatever I could scrounge, I cut some ribs from 1/4” ply and decided that they were far too heavy and unnecessarily strong for a 2 strut wing so I made them from 1/8”ply with pine cap strips, ply leading edge cover, I covered the wings with linen (don’t think Ceconite was around, I hadn’t heard of it), used a wire braced spring steel UC, Fin and Rudder (couldn’t get the high strength alloy tube). Had a 1300 VW bolted to the ply firewall, flew OK (only did short hops incase). It was destroyed in a bushfire before I got caught.
 

robertl

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I like wood and aluminum the best. But, wood is not the cheapest construction now. Not only the price of wood out of this world but the shipping is even worse. Believe building in aluminum now is the least costly way now.
[/QUOTE]

Pops, I built the wings and tail group for a Zenith CH-701 and found it to be fairly easy, all built from scratch. I did purchase the, Home Built Help videos for aluminum construction before I started and decided, hey, I can do this, and I learned some new skills in the process. I eventually sold the project before it was completed but I like wouking with aluminum. And if an, Aluminum VP II was ever designed, I think I would build one.
Bob
 

Pops

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I have built all the aluminum parts for 2 Bearhawk wings (4 panels) and enjoyed it. Repaired C-172 wings and reskinned, stab, elevators and ailerons.

Picture of all parts for a bearhawk wings except for the spar webs and skins.
 

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cluttonfred

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To be clear, I welcome examples of easy to build cantilever wings in other materials than wood. We had some threads a while back on some early Vickers metal construction using angles and corrugated webs. A metal box spar using off the shelf commercial angles or built up from stock sizes of tubing could be very appealing, but I have not yet seen something like that which seems unintimidating to a new builder. I do often go back the Fred Weick’s Ercoupe wing as one example of simplicity in metal construction. I think you could do all the ribs with the rubber mallet technique and just two CNC-cut two-sided templates, one for the straight root/tip/nose ribs and one for the diagonals.

EABEB168-0DEB-4269-82CD-00C5C7AB3A84.jpg
 
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Vigilant1

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If commercialization is a goal, I suppose it would be very useful to do a market study of folks who are prospective airplane builders to determine which construction technique they believe meets the "I could build that" standard.
Some things that look hard to the uninitiated are truly easy, and some things that look easy are hard. To stand the best chance of success, it has to be easy AND look easy. If you have to explain how easy it is, the battle is almost surely lost before it has started.
 

speedracer

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In declining order of "expensive": molded composite, matched-hole aluminum, hand-layup moldless composite.

(And yes, I'm aware that "everyone knows" that moldless composite involves "thousands of hours of sanding." That's about as valid as what "everyone knows" about VW conversions. There's a reason RAF chose it for its early kits, and Scaled for its early rapid prototyping.)
Topaz, you're right about some people thinking (thousands of hours of sanding). I've built two Long EZ's and the actual hours of sanding is closer to 250. It just SEEMS like thousands of hours because it's the only part of building a moldless composite airplane that isn't interesting and fun.
 

blane.c

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Under the premise that the fuselage is to be built from aluminum, why would you change material choice for the wings? It is not clear how that makes sense. Why not the same materials throughout the majority of the major structural components unless impractical for some reason?

Even if aluminum is less expensive is it the clear choice for a 21st century plane? Composite just says 21st century in a clearer voice to me. Because 3D printers and computer aided machining tools are becoming more common the molds and non structural parts could be digitized. If you need a wing rib you just print the mold or cnc a piece of foam to shape. How the mold is filled or the foam is covered may require different techniques but anybody anywhere can have identical parts to work with.

If one was willing and could afford to experiment, (your fault cluttenfred you introduced the idea) Nenadovic' biplane configuration the wings could be short, light, no struts and the pilot could be more or less under the forward wing parasol or cabin.
 

cluttonfred

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I have no problems mixing materials and construction techniques if there isn't too much of a learning curve involved. Every wooden aircraft I know of has many steel and sometimes aluminum parts and most have composite cowlings and I have seen metal aircraft that still used plywood for the seat and instrument panel.

Blind-riveted square or round aluminum tubes and aluminum gussets are very intuitive and unintimidating, but I have never seen them used for a cantilever wing. Like I said before, a triangular truss might work using an isosceles triangle turned 90 degrees. The base of the triangle forms the spar caps and web and the apex forms the rear or aileron spar.

I would be interested to hear from the folks with more engineering knowledge than I have whether or not readily-available off-the-shelf round or square tubes or angles would be a good choice for the spar caps and rear spar of an Ercoupe-style wing perhaps using sheet aluminum wrapped over foam ribs forward of the main spar.

1624463383808.png

Under the premise that the fuselage is to be built from aluminum, why would you change material choice for the wings? It is not clear how that makes sense. Why not the same materials throughout the majority of the major structural components unless impractical for some reason?
 

blane.c

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I have no problems mixing materials and construction techniques if there isn't too much of a learning curve involved. Every wooden aircraft I know of has many steel and sometimes aluminum parts and most have composite cowlings and I have seen metal aircraft that still used plywood for the seat and instrument panel.

Blind-riveted square or round aluminum tubes and aluminum gussets are very intuitive and unintimidating, but I have never seen them used for a cantilever wing. Like I said before, a triangular truss might work using an isosceles triangle turned 90 degrees. The base of the triangle forms the spar caps and web and the apex forms the rear or aileron spar.

I would be interested to hear from the folks with more engineering knowledge than I have whether or not readily-available off-the-shelf round or square tubes or angles would be a good choice for the spar caps and rear spar of an Ercoupe-style wing perhaps using sheet aluminum wrapped over foam ribs forward of the main spar.

View attachment 112254
While the original VP's had steel struts and wing connection fittings and other bits the welding was recommended to be farmed out to professionals.
It also had aluminum (the motor mounts, gear legs, and tail post most notably) and composite (the cowling fuel tank and aft fairing) it would still be considered primarily a wood structure and build.

Is there a weight advantage to wooden wing construction over aluminum considering skins are the same?
 

Victor Bravo

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I believe the overarching intent of the VP-21 would be to minimize the overall effort, cost, time, and aggravation for someone to build an economical little conventional runabout airplane. That was pretty close to what Evans set out to do with the average home DIY person's skills in 1968.

Today, considering people's microscopic attention spans AND the breakthroughs in CNC AND the re-shuffling in material costs, aluminum makes a lot of sense.

To address some of the recent posts in this thread, I must reiterate that there is a dollar value and a time value to keeping the same primary materials for all the large parts of the airplane. If you set up your shop to build a sheet metal fuselage, then you have to set it up differently to build a wood or composite wing, there will be some net loss in efficiency, cost, learning curve, tooling, shop consumables, etc. etc.

I'm sorry but this entropy will slow down or increase the cost of a project to one degree or another. So if you are solving the equation for an easy, low-stress, and smooth build project for a first-time builder, the big parts all ought to be the same material from start to finish.

If you are solving the equation to learn as many new skills as you can, and have an airplane at the end, then that is an entirely different thing.
 
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Bigshu

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True enough but, by the same token, nothing is limiting you to a VW in the first place. Why spend a bucket of money on "souping up" a VW conversion when you could spend the same amount of dollars on a used O-200? The point of doing an auto conversion is "inexpensive purchase and maintenance." If you're going to drop the dollars, might as well go for something that's more suitable from the get-go.
That's a great point, but my interest in auto conversions has more to do with the advantages of modern auto engine design, not the expense of a conversion. I think a fuel injected, electronic ignition engine without the added mess of dual ignition, and built from the start to use lead free fuel makes the most sense these days. That leaves most used aero engines out. The advances in engine systems seems like it would be harder to replicate on an aero engine. For instance, I can take my pick of at least three different fuel injection solutions for a Corvair, about as many electronic ignition setups. No mods required for single ignition, etc.
Your point is well taken that the discussion of a VP-21 should strongly focus on keeping it accessible cost wise. And the historical point that longer span, 65hp aircraft were common things back in the day makes me think that maybe a simple, inexpensive to build and own aircraft doesn't satisfy the modern thrill seeker's need for speed. Truth be told, I've always felt cruise speed at or around 100mph is plenty, I just want a roomy cockpit, and easy access (I'm not as limber as I used to be).
 

cluttonfred

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Well said, VB, so if we choose blind-riveted aluminum tube and gusset covered in fabric as the preferred method, how best to tackle a simple, constant-chord, squared off, cantilever wing using that construction style?

If you are solving the equation to learn as many new skills as you can, and have an airplane at the end, then that is an entirely different thing.
 
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