Airfoil Shapes?

[gbanse]

Is there a good resource (book,mag, website) for learning what the different shapes/designs of the more common airfoils are and what they're good for (e.g. slow flight, aerobatics)?

Gregg

[Sail 'n Soar]

Airfoil Sections by John Malkin has more foils than you will ever use. As for what they are good for, almost any of the model design books has a good discussion on airfoil selection. The general rule is something like highly cambered for trainers and slow flight (flat-bottomed foils are relatively highly cambered), semi-symmetrical for general sport use, and symmetrical for aerobatics. Don't go to fat. For moderate to small models stay below 15% (I personally choose between 10% and 12% foils for reasonable performance at model scales) While some of the thinner NACA 4 series work well enough, many of the Eppler and all of the Selig foils were specifically designed for model-scale applications. The Epplers and Seligs are especially popular among sailplane modelers because of their high performance; however, if you are building foam or film-over stick structure wings, the'll work fine, but you aren't going to see their full potential.

[DLC]

You can find coordinates, drag polars curves and lift coeff. versus angle of attack for a lot of airfoils at

www.nasg.com

When the page comes up, click on ENGLISH, then click on Airfoil Database

[gbanse]

Sail n' Soar,
John's book seems to be out-of-print or available only in NZ. But I appreciate the response regardless.

DLC,
Thanks for the response. Is there a way to view the results in English? It gives me numbers but the descriptions of what they are is in Japanese.

GB

[Dereck]

Gregg
Cheap (free!) and cheerful program for looking at airfoil shapes is "Profili". Freeware, it's still around in odd places. Italian, but with English version on board. More for when you've figured out what airfoil the new killer design needs.

For reading material, either anything by Martin Simons - slanted towards soarers a tad, but closing on powered flying in the new edition, I understand. Howard Chevalier also wrote a very modeller friendly book on aerodynamics - can't recall the title, sitting here in my office, but I recall "Flying Models" magazine being one good source.

Regards

D

[gbanse]

Thanks for the info Dereck,

Martin's name keeps coming up in my searches for resources. I'm not looking to design a plane as much as I want to understand why a few select planes were designed the way they were starting with the DH Mosquito. I'm in search of the original plans for this plane now with hopes of developing my own scale drawings. I figured I'd need to understand their design concepts thus I'm looking for good resources on airfoils.

Gregg

[steve lewin]

Ah you should have said you were interested in full size not models. The web site you want is Selig's http://www-aero.aae.uiuc.edu/~m-selig/ though I can't actually get to it at the moment. He has the plots for about 1000 different airfoils and a wonderful guide to the airfoils used in thousands of planes.

BTW your chances of getting "original" drawings for any DH plane are pretty remote. There are many good sources of 3-views out there though, not to mention a lot of Mosquitos to crawl round and take pictures of.

Steve

[rpage53]

Originally posted by gbanse
I want to understand why a few select planes were designed the way they were starting with the DH Mosquito.
First, put yourself in the middle of a war zone ;)

WWII designs were often created out of necessity and the reasons may be known only to the original designer. The Mossie evolved from the Comet racer, so start there. The Mosquito was intended to be built with wood instead of scarce metal, but that also required smoother, more rounded shapes. The shape of the tail is strictly because it created a distinctive DH silhouette. Not an aerodynamic purpose.

You can see which airfoil was used in this listing,
http://amber.aae.uiuc.edu/~m-selig/ads/aircraft.html
but understanding why will require some historical research
http://www.nasm.si.edu/nasm/aero/aircraft/dehavilland_mosquito.htm
http://www.mossie.org/

Rick.

[gbanse]

Steve,
Thanks for the post.

"Ah you should have said you were interested in full size not models."

But I'm not. :) My goal is to build a scale model of the Mossie. I want to start from scratch - meaning my own plans rather than using someone else's scaled plans or kit.

I'm chasing down a few leads for the original plans - a few folks out there are actually rebuilding an existing mossie or building one from scratch so they have to be using some sort of plans. One guy in NZ has a complete set. Says it's as thick as a telephone directory LOL! I'm not looking for all parts though, just the 3 view drawings with some dimensional info on exterior items.

So the point of understanding the airfoils comes in when/if I have to adapt the original design to accomodate the model's speed. I'd like to be as true to the original but if reality dictates an adjustment, I'll be better prepared.

rpage53,
Thanks for the post.

re: warzone - LOL! You are most likely right. If the design & construction of these warbirds is anything like I imagine, then much of the work and designs went into production at 80% complete and they figured out the rest as they needed to.

I can't get to that first link you posted and have been to mossie.org. Thanks for the info.

Gregg

[rpage53]

The computer in Urbana seems to be down. Hope it is only temporary.

The Mossie used a modified RAF 34 though which was popular at the time.
http://www.nasg.com/afdb/afshow.phtml?n=1&file1=raf34.dat&name1=RAF34

Rick.

[Sail 'n Soar]

gbanse

I, too recommend Martin Simons "Model Aircraft Aerodynamics" . I have his edition published in 1983 and assume it has been improved since. Yes, it is primarily focused on sailplanes, but the topics covered are easily understandable and equally applicable to powered planes. It provides loads of equations describing lift, parasitic and induced drag, power requirements as a function of aspect ratio, etc.

Unfortunately I've found no book which covers all of the model design aspects well. For instance, unless it has been corrected in the later editions, while Martin's book provides a good understanding of the various control and stability design considerations, it stops short of giving you what you need to design a successful model. Specifically, at least for my edition it doesn't provide and equations or guidance relating to general proportions and such things as stabilizer size/tail volume.

I also have Andy Lennon's "Basics of R/C Model Aircraft Design." This book is REALLY focused on wet propulsion and designs for wing loadings above my skill level. In addition to everything else, he has chapters on such things as vertical tail design and spiral stability and horizontal tail design, and propeller selection.

My approach is to buy every book on the topic and pick from each what works for me.

[DLC]

Re. the nasg.com site: the third line on the home page should be
'In English'
underlined. Click on that and the text will be shown in English

[gbanse]

Hello S n' S,
Yes, it's looking to me like the hobby/sport is still in its infancy. No plethora of books on the same subject - which is a nice change of pace but stinks in a way. Cake is highly overrated anyhow. ;)

Re: buying books. In my profession I buy a few books but not until I've done research to determine which ones are the better for what I want to learn. I simply can't afford to buy all that I want. So, I have to pick and choose. That's why this Board (read: y'all) is quickly becoming invaluable to me.

Gregg

[gbanse]

Hey DLC,
That's what I tried but the results of my search were in Japanese. This time however, they were in English. ... go figure.

Thanks.

Gregg