Poor Man's Aero: Wingin' It

[Jack Olsen]

I recently did some testing with my add-on wing for a ducktail. It worked well, but the wing I'm using is only 42 inches wide. I'd like to try a couple of other widths (50-inch, 60-inch), but these things are priced a little on the ridiculous side.

This picture got me thinking:



Rather than spending a thousand bucks for someone else's fabrication time, it occurred to me that I could probably do my own R&D, and then put together a wing with some aluminum that would do the job, and conceivably allow me to test different widths, lengths, and even NACA profiles.

What's a NACA profile, some of you might ask? Well, I just learned. It's a 4-digit, 5-digit or 6-digit number that describes the profile shape of a wing. Some shapes are better at different angles of attack, and (I assume) different lengths, widths, etc. It seems like I could get the correct NACA profile and cut out a half dozen identical profile pieces, srting them along a length of aluminum tubing (maybe box tubing?), and then cover the thing in a thin aluminum skin that's conformed to the shape.

It seems pretty simple. But then, to an idiot, everything seems pretty simple.

Aero and fabrication experts: am I out of line on this? Would it work?

Naturally, I don't have the time to do it right now.

But all my ideas for projects seem to come to me when I'm busy doing something else.

[RaceProEngineer]

Jack,

We tried it, for exactly the same reasons you mention (Cost of long span wings, seeming simplicity of construction, availability of aluminum). I will not go so far as to say the results were "laughable", but we abandoned it very quickly!

That being said, we have seen, and admired, some of your "handiwork". Give it a try, and treat it as a learning experience. If you want an idea of what is really involved in producing an effective aero piece, call John Goss at Pennon Composites 315-498-4401.

Incidentally, the longer span wing is much more effective than the wider cord, but you probably already know that.

Ed LoPresti

[randywebb]

Yes, it will work. You need to be able to form Al sheet or CF sheets, whatever. I would be tempted to try foam crosspieces in the non-bearing parts and something stronger where the side pieces will join.

Remember, NACA was formed during the jet age. You will want profiles that are designed for slower speeds -- they may have such but that was not NACA's focus... NACA evolved from a C (committee) into an S (Space Agency) - NASA.

Find some of the English translations of dear ol' Prof. Kamm - they amy have some nicer profiles for you, if the NACA stuff is all too high speed.

Have Fun!

[TimT]

Have a look at "Competion Car Downforce, A Practical Handbook" Auth. Simon McBeath.

He has a chapter outlining how to build a wing, but it looks like you have a handle on how to proceed anyway.

An idea might be to extend your existing wings length

[Jack Olsen]

Originally posted by RaceProEngineer
We tried it, for exactly the same reasons you mention (Cost of long span wings, seeming simplicity of construction, availability of aluminum). I will not go so far as to say the results were "laughable", but we abandoned it very quickly!

If you saw some of my rejected efforts, you'd know that 'laughable' might be my middle name.

For quick and dirty work, I was thinking of using generous amounts of adhesive. Does anyone know of an adhesive that remains slightly flexible, and is also light and effective on aluminum?

And does anyone want to throw out any NACA suggestions? Plenty of websites will give me a specific drawing if I enter the numbers.

Here are some of the pre-1929 versions (inverted for car use).

[Jack Olsen]

Originally posted by TimT
Have a look at "Competion Car Downforce, A Practical Handbook" Auth. Simon McBeath.

Just ordered it. Thanks.

[rsNINESOOPER]

Hey, just a thought but what about building a "HOT WIRE" foam cutter and using high density foam (2"-4"thick roof insulation panels, Home Depot) to cut your shapes out of thus creating your wings in a fraction of the time to fab out of aluminum. Then you cover with glass or carbon fiber which is fairly easy to work with. Model airplane junkies have been using this low tech method for quite some time and its cheap and easy to build a setup to cut your foam blanks in any profile you want. If ridgidity is an issue it is quite common to use a hollow aluminum spine down the length of the wing which when coupled with an outer skin of fiberglass or carbon is extreamly ridgid. I have a buddy who has made these things and built some very large and very complex compound taper wings that are over 60" (P51 mustang wings) so I have seen it done first hand, so simple but so trick.

Here is a link for building the exact setup I just mentioned-

http://members.fortunecity.co.uk/slmohr/rcinterest2.htm

[jevvy]

Nice work Jack - dont laff but it might be worth swinging by an RC model shop and see what they have that inspires you - Most wings for RC planes are made in the scale that you might be looking at, even if it gives you some construction techniques it may be worth the trip.

As rsNINESOOPER shows in his link the RC bunch are a creative lot and always into DIY so you might strike lucky - Also make sure you look at EPP foam, I have a few combat wings made out of that stuff and its totally indestructable and light - you might even be able to buy EPP wing blanks to use as a starter then get them beefed up and covered with something.

FWIW I can give a non flying mate a go of my EPP plane and he can crash it nose first at full speed into the ground(the propellor is on the back), we pick it up, dust it off and throw it back in the air!

[jevvy]

Heres a link with some decent pics and info - seems he could cut stuff big enough for you:

http://www.flyingfoam.com/launch.html

[Jack Olsen]

RC aircraft -- I love it -- that's outside-the-box thinking.

No Porsche Tax.

I sent an email to the foam cutter guy.

[Peter Bull]

A popular solution is to take a NACA profile and superimpose a third degree equation on its camber line. By doing that you get a wing profile which is less sensitive to stall. It is, however, not as efficient as the NACA without the superimposed eqation. By efficient I mean the amount of lift it creates in relation to the drag it creates. But since the air flow behind a car is very disturbed it is better to use a wing profile which do not stall easily.

Below I have attached an image of a NACA 23012 profile, with, and without the superimposed 3rd degree equation.


The fun thing is that by using an equation you can play with the parameters to make a profile which suits you.

About the glue, 3M has a spray glue called #77 which is very good. Generally alumium is not easy to glue, but if you use an alumium foil the 3M 77 should work fine. I would not use it on construction foam however. The solvents might dissolve the foam. Then an epoxy would be better.

/Peter

[FLATTOP]

Just a quick irony: For us, the purpose of a wings are to PREVENT flight!

Johan

[krauthead]

Funny, My first reaction was that the superimposed profile on that graph looks like a section through a RSA wing.

[Asjac]

It also may be easier to just lay some 'glass or CF on the exterior of the profile. This way the skin is bonded to the core and you get a durable edge. Either CF or FG are the same work to install, only the price changes.

I think if you find an aluminum that is soft enough to form, it will be too soft to serve as a structural member that the skin needs to be.

[RarlyL8]

Just saw your thread. Beat me to the RC line of thinking. My dad is an RC nut who has been building planes big enough that a dog could fit for probably 60 years. It's not just a good idea but a "must do" if you are experimenting. RC stuff is cheap and easy to work with.

I have been wanting to add a wing to a duck a la 996GT3 for some time now. The wing is not an issue for me, it is the attachment to the duck. How do you plan to integrate the wing to the duck?

[RarlyL8]

Here is what I had in mind to mimic:

[304065]

Jack.

If you start hot-wiring, take a page out of the experimental aircraft builder's book: DO NOT HOT-WIRE URETHANE or POLYURETHANE FOAM. It releases Cyanide Gas, you do not want to be doing an impression of Zyklon B in your garage.

A hotwire rig can be easily built at home with a wood frame and a piece of nicrhome wire. Put the NACA profile on a pair of wood end plates on a long rectangle of foam and have a friend help you make the cut. Cover the surface with plastic and you're in business.

Jack, of all the airfoils out there, I would use what's called a "Clark Y." It's famous as the Piper Cub airfoil.

[RaceProEngineer]

Originally posted by RaceProEngineer
call John Goss at Pennon Composites 315-498-4401.

Reinventing the wheel is lots of fun, and conjecture about hi-density foam, and theories about adhesives, and what MIGHT work with what . . .

There is a lot more to it than that, gentlemen! For instance, if one were to build a cantilevered wing (as in the nice normalized cord-view diagram), in a 6-feet span, using a thin aluminum thru-tube and foam, wrapped in aluminum, and attach it on either end with solid end-plate struts, one would be flirting with disaster.

Or you could call John, who does this stuff all the time, and not with 15 pound model airplanes.

[88911coupe]

What about the guys who hand form surfboards...could they be of some help on the fabrication?

[ZOA NOM]

Jack, this has been perfected already: