# 21st century Volksplane?

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#### cluttonfred

##### Well-Known Member
HBA Supporter
Thanks, blane.c, but the Bearhawk uses a strut-braced wing.

#### blane.c

##### Well-Known Member
HBA Supporter
Yes it does, but the point is light weight and aluminum skin covered. Of course heavier cantilevered but as with any other style of wing.

The other thing is The Bearhawk is lighter than the vast majority of Cubs with the same hp. And it with a aluminum skinned wing (more efficient without all the swells). So point again is light weight and aluminum skin.

Edit ... maybe I have it backwards. A aluminum skinned wing is more efficient because it doesn't have all the swells. Efficiency is a point worth considering?

2cd Edit ... If you were designing it as a one-off, would you consider a tapered cantilevered smooth skinned wing because it would be more efficient for VW engine in a two place aircraft? And then how many concessions can you make from there? So square wings for easier build is one concession ... etc.

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#### patrickrio

##### Well-Known Member
universal pivot so you can rotate the whole wing
I really think this is an underused portability feature. I think that this can also be used very effectively with tip folding for wings longer than the depth of a typical storage area.... say longer than 20 feet. The folds are much less structurally complicated the closer they are to wingtips....

I really want to see how this feature works with a modern, efficient, high wing ultralight motorglider style aircraft.

#### blane.c

##### Well-Known Member
HBA Supporter
I really think this is an underused portability feature. I think that this can also be used very effectively with tip folding for wings longer than the depth of a typical storage area.... say longer than 20 feet. The folds are much less structurally complicated the closer they are to wingtips....

I really want to see how this feature works with a modern, efficient, high wing ultralight motorglider style aircraft.
Portability and Storage are two different things. Removing/folding wings for Storage is a whole different numbers game for structure of an aircraft than portability as in "road worthy". A "road worthy" airframe has to be more robust and heavier.

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#### Vigilant1

##### Well-Known Member
Metal wing: It seems to me that unless the rivet holes are truly 100% matched (no need to " cleco, counterbore, de-cleco, debur, rivet", 500 times, but instead it is just "cleco, rivet"), does it meet the 2021 "easy to build" standard? It may be possible for the CNC flatbed router at the local maker space to attain that level of precision on the flat skin panels, but there's no way to do it for the ribs (because of the flange bends). So, virtually every hole will be a 6 step process with a couple of "take everything apart again" requirements. "Regular" plans builders and kit builders are used to this, but would it be right for this VP project?

Have I got this wrong?

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#### blane.c

##### Well-Known Member
HBA Supporter
Metal wing: It seems to me that unless the rivet holes are truly 100% matched (no need to " cleco, counterbore, de-cleco, debur, rivet", 500 times, but instead it is just "cleco, rivet"), does it meet the 2021 "easy to build" standard? It may be possible for the CNC flatbed router at the local maker space to attain that level of precision on the flat skin panels, but there's no way to do it for the ribs (because of the flange bends).

Have I got this wrong?
Yes.

#### Sockmonkey

##### Well-Known Member
Portability and Storage are two different things. Removing/folding wings for Storage is a whole different numbers game for structure of an aircraft than portability as in "road worthy". A "road worthy" airframe has to be more robust and heavier.
Right, the pivoting is intended for easy storage because it's easier to have a long shed or long space in a hangar than a long and wide one.
You don't want to take it on a trailer like that because the wing would catch a lot of air.
For transport you unhook the central pivot as well to remove the whole wing.
A aluminum skinned wing is more efficient because it doesn't have all the swells.
If you mean the slight bulge of the ribs through the fabric, those aren't going to hurt your performance noticeably.

#### cluttonfred

##### Well-Known Member
HBA Supporter
No, you're not wrong, I have the same impression and that tends to confirm my earlier instinct to stick with fabric covering over metal rather than all-metal construction if I were to switch from wood.

Metal wing: It seems to me that unless the rivet holes are truly 100% matched (no need to " cleco, counterbore, de-cleco, debur, rivet", 500 times, but instead it is just "cleco, rivet"), does it meet the 2021 "easy to build" standard? It may be possible for the CNC flatbed router at the local maker space to attain that level of precision on the flat skin panels, but there's no way to do it for the ribs (because of the flange bends).

Have I got this wrong?

#### Vigilant1

##### Well-Known Member
No, you're not wrong, I have the same impression and that tends to confirm my earlier instinct to stick with fabric covering over metal rather than all-metal construction if I were to switch from wood.
I do like the foam ribs with plywood capstrips as done by some Pou builders, you mentioned it in this post:
Foam ribs with plywood capstrips?

The foam ribs could be CNC cut if desired, or hot wired. Not much plywood is required, and the whole mystery/problem of glueing to aluminum is avoided. Cheap, light, not hard to do.
Or, (maybe better) rather than the plywood capstrips, fold a piece of fiberglass tape over the edges of the foam rib. The FG tape adhered to the rib faces will remove the peel forces that otherwise occur at the edge of a capstrip.
Or, just one layer of FG across the rib face on one side and folded over the top and bottom edge of the rib and a short distance onto the other side would provide a foam-free load path for tension from one side of the wing to the other.

Just to beat the dead horse: A hot-wired and fiberglassed D cell at the front of this wing with the spar at the aft face would go together fast. No need to sand and fill the composite at all, wrap the fabric cover over everything at once.

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#### mcrae0104

##### Well-Known Member
HBA Supporter
Log Member
It's amazing what you can do from scratch with a few tools.
Bob
Case in point: my friend Dustin's Bearhawk build. Minimal space, minimal tools.

#### Lars Odeen

##### Member
Stopped at Lowes box store to get a quick dose of sticker shock. Getting land ready to build a cabin and having the septic system installed.
Have a list of common size of lumber that I have been keeping track of. Plywood is even higher that a month ago, at a all time high, framing lumber about the same sky high prices, treated decking boards are ( 1"x6"x12') down to $12+ from a high of$18+ a few months ago.
Going to hold off the build for a while to see how the prices go.
For what it's worth I work in the timber industry. I would expect prices to continue to dip, how far is anyone's guess at this point.

#### Pops

##### Well-Known Member
HBA Supporter
Log Member
For what it's worth I work in the timber industry. I would expect prices to continue to dip, how far is anyone's guess at this point.
Just a dip ? Just not requiring the first born would be nice.

#### rotax618

##### Well-Known Member
For ease of construction the Strojnik method is worth a look, the only downside is the spar which is alloy bonded to plywood, perhaps a simple rectangular or tubular extrusion spar could be designed. Strojnik uses ply ribs with fibreglass skins which are laid up on Mylar sheets and formed to airfoil shape while still rubbery, before curing - giving a very smooth outer surface, could use foam intermediate ribs to save weight and preserve airfoil shape.His wings have a rectangular centre section with removable tapered tips (could also be rectangular)

#### Victor Bravo

##### Well-Known Member
HBA Supporter
I have a couple of aerospace drill-reamer bits. The end is a drill and the shank is a reamer. Does a good job, quickly.

So if you had a CNC "75% matched hole" sheet metal airplane, which is within the capabilities of a "normal" CNC, you'd CNC the holes to #40, Cleco it together with silver Clecos, and then set the Cleco'ed wing down on the workbench, blocked up level for no twists just like a balsa model airplane.

Then you'd run the #30 drill reamer through all the holes at once (Clecoing as you go, with copper 1/8 Clecos), and then take the skins off and use the Heintz method of deburring ribs and skinswith a 2" Scotchbrite disk in a small air grinder.

Then you'd Cleco it back together and start riveting.

Our VP-21 is not going to be a show quality RV any more than the Zenith airplanes are. Heintz' instructions for the701 specifically say "don't try to make this something it is not going to be".

But there is another way as well. Have a drilling fixture that the formed, hammered, straightened rib fits into. With the rib in this jig, run the #40 drill through drill bushings that are part of the jig. The locations of these drill bushings match the holes that are CNC cut into the skins. Using this method, you could probably get a lot better than 75% "matched hole" alignment.

#### Lars Odeen

##### Member
Just a dip ? Just not requiring the first born would be nice.
I can't argue with that!

#### erkki67

##### Well-Known Member
I'm leaning in this direction, where you have a nice high AR strut-braced high wing.
Tandem seating for two.
Center mount is a universal pivot so you can rotate the whole wing easily by unhooking the side struts from the fuselage.
Has to be two-axis, but that comes with a benefit.
With no pedals, you can slide the front seat back when flying solo so you keep the same CG.
Just have an extendable bit on the yoke so you can still comfortably reach it.
There ya go.

Why not making elevons, so it would remain a 3-axis?!

#### Sockmonkey

##### Well-Known Member
Why not making elevons, so it would remain a 3-axis?!
I explained that.
It's so you can easily rotate the wing for storage and so you can re-position the pilot without messing with the CG

#### Bigshu

##### Well-Known Member
Metal wing: It seems to me that unless the rivet holes are truly 100% matched (no need to " cleco, counterbore, de-cleco, debur, rivet", 500 times, but instead it is just "cleco, rivet"), does it meet the 2021 "easy to build" standard? It may be possible for the CNC flatbed router at the local maker space to attain that level of precision on the flat skin panels, but there's no way to do it for the ribs (because of the flange bends). So, virtually every hole will be a 6 step process with a couple of "take everything apart again" requirements. "Regular" plans builders and kit builders are used to this, but would it be right for this VP project?

Have I got this wrong?
Don't Vans and Zenith both advertise 100% match hole kits? That would include the ribs, right? Do you have to deburr punched holes?

#### Vigilant1

##### Well-Known Member
Don't Vans and Zenith both advertise 100% match hole kits? That would include the ribs, right? Do you have to deburr punched holes?
Some do, some don't. Last I checked, the RV-12, RV-10 required no updrolling and deburring, others did.
At any rate, factory drilling to a final hole size requires very precise alignment. I suspect the rib flanges have to be bent, then drilled. That's not something a local maker space can do. At this point we are talking about a very high level kit, not a plans built plane with local fabrication of some parts.

Folks today assemble a coffee table from Ikea in 15 minutes and brag to their friends that "I built that." I don't know how that person will feel about building and taking his wing apart several times, working on every hole more than once.
Metal airplane fabrication works great, and has for decades. I'm just wondering if traditional, or even "pretty good" prefab assistance meets the requirements of our target audience.

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#### Victor Bravo

##### Well-Known Member
HBA Supporter
Metal airplane fabrication works great, and has for decades. I'm just wondering if traditional, or even "pretty good" prefab assistance meets the requirements of our target audience.
The issue of people's pathetic attention span and unwillingness to take more than 15 minutes to "build" something is a different problem.

But apples to apples, I'm willing to bet that even doing three operations on each hole and pop riveting is less overall effort than other methods.

If you created a high-end composite molded kit that had very large joining flanges, and simply gluing those joining flanges together with flox resulted in the finished construction (no crawling through the fuselage taping over the joints) - then I'm sure you could wind up with a lower total build time than pop riveted tinfoil. But I'm also pretty sure that would be a very expensive kit, and the tooling/development cost would put it outside of the lowbuck "people's airplane" this thread is about.