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-   -   Aerodynamic tools, calculators and test links (http://www.rcuniverse.com/forum/aerodynamics-76/2867994-aerodynamic-tools-calculators-test-links.html)

BMatthews 04-11-2005 11:19 PM

Aerodynamic tools, calculators and test links
 
This is a new sticky FAQ thread to post up links to various online calculators, simulators and other online software tools that can be used to explain principles or calculate aerodynamic design factors. I'll edit this post to include all links as they come up to save users from wading through all the posts. Headings for some but not all categories are shown below and the links along with a short description are posted under the headings. If you have suggestions for other heading topics please post.

Bring 'em on folks!
__________________________________________________ _____

Airfoil analysis and airflow simulation:
http://www.grc.nasa.gov/WWW/K-12/airplane/foil2.html - Foilsim, a simple airflow simulator. Let's you play with camber, AoA and determine the Cl of your basic design size and speed. Very educational - BMatthews

CG calculators:

MAC (Mean Aerodynamic Chord) calculators:
http://perso.wanadoo.fr/scherrer/mat...glish/mce.html - multi panel entry allows more complex shapes -Tall Paul

Tail Volume Coefficients- Horizontal and Vertical:


kamakasi 04-17-2005 10:23 AM

RE: Aerodynamic tools, calculators and test links
 
here is one for a [link=http://www.mmaa-modelairplanes.org]effective dihedral angle calculator[/link] I've also got a good c/g locator if I can relocate the file I'll post it.

kamakasi 04-17-2005 10:36 AM

RE: Aerodynamic tools, calculators and test links
 
Found the c/g program, not the one I originally had but it looks like it has all the bells and whistles. [link=http://www.coloradogliders.com/aircraftbalancecalculator.htm]Aircraft Balance Calculator[/link]
You might wand to check out[link=http:///www.coloradogliders.com/tools.htm#tools]colorado gliders[/link] they seem to really get into the #'s. Mostly glider stuff but we follow the same physical laws as everyone else

BMatthews 05-03-2005 08:46 PM

RE: Aerodynamic tools, calculators and test links
 

Quote:

ORIGINAL: Geistware

OK Everyone, Version 6.0 of the calculator are up and does balance calculations as well as CG. Please review it here.

http://www.geistware.com/rcmodeling/cg_super_calc.htm

Wing-Ding 05-05-2005 12:09 AM

RE: Aerodynamic tools, calculators and test links
 
Here is a software tool (spreadsheet) that converts surface deflection expressed in inches to degrees:

[link=http://www.aeroperfect.com/degree.html]www.aeroperfect.com/degree.html[/link]

And two spreadsheets that aid in programming Hitec Digital Servos:

[link=http://www.aeroperfect.com/program_off-plane.html]www.aeroperfect.com/program_off-plane.html[/link]

[link=http://www.aeroperfect.com/program_on-plane.html]www.aeroperfect.com/program_on-plane.html[/link]

While these are "online software tools", they're not tools for calculating aerodynamic design factors in the strict sense. While they are useful, they may outside what you had in mind. If so, please feel free to remove this post

adam_one 06-26-2005 03:51 PM

RE: Aerodynamic tools, calculators and test links
 

[link=http://adamone.rchomepage.com/design.htm#calculate]Calculate wingloading, area and estimate stall speed[/link]

[link=http://adamone.rchomepage.com/cg2_calc.htm]Calculate NP & CG for wings with two different panels[/link]

BMatthews 10-29-2005 03:41 PM

RE: Aerodynamic tools, calculators and test links
 
Online servo torque calculators...

http://www.csd.net/~cgadd/eflight/calcs_servo.htm

a second site with the same thing

http://www.coloradogliders.com/servo...calculator.htm

and again...

http://www.mmaa-modelairplanes.org/s...calculator.htm

and just in case all the rest go dead a 4th iteration of the same thing

http://www.flyrc.dk/servo.htm

Just be sure you provide a worst case speed of what the model will be able to do in a screaming death dive. And to prevent loading the servo you should use the number given by the calculator for servo torque required and get ones that provide 1.5 to 2 times that torque calc so you know the servo won't be operating near it's stall zone.


Enjoy!

VTaerospace 11-14-2005 05:11 PM

RE: Aerodynamic tools, calculators and test links
 
http://www.mh-aerotools.de/airfoils/index.htm is a great resource. It has quite a few programs for model aircraft design. Noteably, JavaFoil a 2D airfoil analysis tool, JavaProp, and Java Pipe. There are also many other programs available on Dr. Hepperle's website. You just have to look around a bit. A one i find handy often is the aerodynamic center calculator.

And for the more advanced and adventurous out there, AVL is a great 3 dimensional aerodynamic analysis tool. Google it. You'll find it.

Aschiuta 12-24-2005 05:31 PM

RE: Aerodynamic tools, calculators and test links
 
Using the java applet from here http://www.mh-aerotools.de/airfoils/javafoil.htm i design the airfoil from my scratch build aircraft The Beast.
Great tool!

cyclops2 12-29-2005 08:47 PM

RE: Aerodynamic tools, calculators and test links
 
Is there any site that has airfoils grouped, as to the type of aircraft use? I am looking for a site that visually shows the foil.
I found a perfect such site in Japan, but all the foils were in reference #'s and plotting #'s.
I live and die on print out and enlarge.
Thanks for any sites, Rich.

Aschiuta 12-29-2005 09:06 PM

RE: Aerodynamic tools, calculators and test links
 
No i do not know such a site.
you can take a look here-> [link=http://www.ae.uiuc.edu/m-selig/ads/coord_database.html]UIUC airfoil databse[/link]
You have both numerical data and the image.


cyclops2 12-29-2005 10:09 PM

RE: Aerodynamic tools, calculators and test links
 
After looking at most of the foils visually. I come away with the truthfull realization that no one agrees what is the most efficient in any application after all these years.
Thanks for removing any doubts I had about airfoil selection. [sm=thumbup.gif]

Aschiuta 12-29-2005 10:18 PM

RE: Aerodynamic tools, calculators and test links
 
Well, there is no perfect airfoil for everything... depends of what are your requirements for that aircraft (speed, long flying time, maneuvrability etc etc), you have to pick the best airfoil to suit that. And of course, even if you know the requirements, you will still have hard time to pick the best . I know maybe it sound a little be off, but think about of formula 1 wings and body aerodynamics.. there is no perfect way, no perfect package, and also the package is modified to suit the circuit, and it is in always development.

cyclops2 12-30-2005 12:36 PM

RE: Aerodynamic tools, calculators and test links
 
You are absolutly correct about competitiveness developing better air foils for each condition.

cyclops2 12-30-2005 12:39 PM

RE: Aerodynamic tools, calculators and test links
 
You are absolutly correct about competitiveness developing better air foils for each condition.
Why would I expect the competitors to all admit, 1 was now the best for a particular setup.
I can be very simplistic at times, because I do not compete actively.

GJM 01-19-2006 12:55 AM

RE: Aerodynamic tools, calculators and test links
 
Is anyone out there aware of a formula for calculating the number of G's a design would be able to pull. It would be helpful when trying to design a structure.

Thanks guys!

rmh 03-29-2006 06:00 PM

RE: Aerodynamic tools, calculators and test links
 
good question
how about asking if that G load exceeds the AOA known to stall the wing?
having watched videos of the Russian S30 doing instant vertical pitch -to produce a flat plate moving thru the air - (the plane is moving 90 degrees to normal flight angle,horizontally) I also wondered where the absolute G load calculation could be determined.
we do these maneuvers routinely on our models but of course they are impossible as proven by volumes of known fact (yawn), etc., etc.,

Oryx 04-15-2006 02:04 AM

RE: Aerodynamic tools, calculators and test links
 

Quote:

ORIGINAL: dick Hanson

good question
how about asking if that G load exceeds the AOA known to stall the wing?
having watched videos of the Russian S30 doing instant vertical pitch -to produce a flat plate moving thru the air - (the plane is moving 90 degrees to normal flight angle,horizontally) I also wondered where the absolute G load calculation could be determined.
we do these maneuvers routinely on our models but of course they are impossible as proven by volumes of known fact (yawn), etc., etc.,
Dick, I don't want to be contentious, but could you point me to a link, article, or aeronautics text book that say any of those maneuvers are impossible, as you state? I am asking this, because not once in my career have I encountered a fellow aeronautical engineer, a text book or an article in a journal stating any of the maneuvers you are refering to cannot be done. In fact, one of the areas in which I work is fighter flight dynamics and there are hundreds of papers in my collection on so-called "super-maneuverability" - and some of those go back to the 70's (although the term wasn't used until the 80s as far as I know). This was long before "3D" became popular on R/C models.

And for what its worth, the maneuvers performed by the Su-30 are done at low speeds and the G-loads are therefore not very high at all... The G-loadings become an issue when maneuvering at higher speeds. A steep turn above the maneuvering speed of the aircraft typically puts a much higher load on the wings than the tumbling maneuvers you see done with the aid of thrust vectoring.

Tall Paul 04-17-2006 11:52 AM

RE: Aerodynamic tools, calculators and test links
 
Quote:

ORIGINAL: cyclops2

After looking at most of the foils visually. I come away with the truthfull realization that no one agrees what is the most efficient in any application after all these years.
Thanks for removing any doubts I had about airfoil selection. [sm=thumbup.gif]

.
True, but also, every worthwhile procedure to get from the leading edge to the trailing edge probably exists in the large databases. There's just so many ways to do that and have a useful shape.
Fitting the shape to the mission takes some delving thru the shapes available, but -the- one you need is there already.

mesae 04-17-2006 12:31 PM

RE: Aerodynamic tools, calculators and test links
 
Quote:

ORIGINAL: GJM

Is anyone out there aware of a formula for calculating the number of G's a design would be able to pull. It would be helpful when trying to design a structure.

Thanks guys!

It's not as simple as your question seems to imply. You would do well to study aerodynamics from a textbook.

There was an interesting thread recently about someone trying to design an airplane to withstand an instantaneous pitch change to 85 degrees AOA at 100 mph or something like that. The drag coefficient topped out for his airfoil at 85 degrees, and was greater than the max lift coefficient at 100 mph. That's a relatively simple way to do it and would result in a very strong airframe, but perhaps heavier than necessary if the airplane never ever does walls at close to 100 mph. You might want try to find that thread.

GJM 04-17-2006 02:51 PM

RE: Aerodynamic tools, calculators and test links
 
Mesae, thank you for the reply.

I figured it was a lot more involved than the way I asked the question. But, I decided it would be one way to start the conversation. I did in fact read the post you are referring to. But as you stated, I thought it would result in a much heavier than necessary structure. Maybe, though, a good start for some of us.

EMVIN 04-20-2006 06:30 AM

RE: Aerodynamic tools, calculators and test links
 
I have been reading this thread and hardly understand any of it...........But, its very interesting and I would like to learn more. Can anyone recommend a textbook or website that can explain aerodynamics for a beginner? It would be nice to have a better understanding as to how my models fly..... and full scale for that matter......

Oryx 04-20-2006 03:19 PM

RE: Aerodynamic tools, calculators and test links
 
Emvin, there are many excellent engineering texts on aerodynamics. However, I think these are not very valuable to most modelers unless you are willing (and interested enough) to really dig into it - and even then it would be tough (but at no means impossible) unless you already have some physics and mathematics background beyond high school.

What I think would be much more useful and enjoyable as an introduction is the book "Model Aircraft Aerodynamics" by Martin Simons. The author is an aeronautical engineer and also a keen modeler. What I enjoyed about the book and why I would recommend it, is that it does away with most of the math and rather explain the concepts of why certain things happen the way they do. Some of it actually gets fairly detailed, but not in a way that intimidates. I got the first edition before studying at university, and still have that one and a newer edition in my collection and I still think it is a great introduction to aerodynamics. You can always follow it up with more advanced texts if you want to learn more, but I really think it is an excellent place to start.

ISBN: 1854861905

EMVIN 04-20-2006 07:52 PM

RE: Aerodynamic tools, calculators and test links
 
Oryx, thanks for pointing me in the right direction.. Model Aircraft Aerodynamics sounds like just what I'm looking for. I will be following this thread trying to learn what I can from it......."Super-Maneuverability" is that a term used in full scale? I know there are fighters out there that have directional thrust....like the Harrier........

Oryx 04-21-2006 12:26 AM

RE: Aerodynamic tools, calculators and test links
 
I think you will enjoy the book, Emvin.

Super-maneuverability is usually what they call the way that some of the modern fighters maneuver. It is often ossociated with thrust vectoring such as installed on some of the Sukhoi prototypes, the X-31, MiG-29OVT/MiG-35 and the F-22. However, it does not necessarily require thrust vectoring - it also includes very high angle of attack maneuvering such as the so-called "Cobra" maneuver that the Russians like to perform at airshows with their Sukhois (even the non-thrust vectoring types). Although the Harrier also has thrust vectoring, it does not usually maneuver in this very high angle-of-attack regime and therefore you would probably not call it capable of super-maneuverability, but the thrust vectoring in flight (VIFF-ing) of the Harrier is a type of direct force control which is another term that you may pick up in literature. Direct force control refers to unconventional maneuvering modes that have also been researched on full-scale aircraft for a long time (some of that actually goes back to early flight, but more specific programmes have been ongoing since the 60's/70s). These include side-force generators on the wings used for flat turns or direct lift control on some STOL aircraft (where you can change your lift quickly without changing pitch or angle-of-attack). Often when you think you just did something very cool in your R/C plane, such as install vertical plates on the wings for direct side-force control, chances are very good that some company or organization already tried it on full-scale aircraft many decades ago. It is very interesting to go through NACA, NASA and AGARD papers from the 40's 50's and 60's: there were some really amazing things that went on in aero-research at the time and much of that continues through today.


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