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Old Jul 21, 2004, 01:11 PM
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WebOCalc - estimate wing and power loading fast!

Over in the Foamies forum, one of the unofficial "Kings of the Foamies", GPW, posted a little info on how he starts his design process. Here's a snippet:
Quote:
First .... the WA ( wing area) is the chord (or average chord ) times the wingspan .....

The weight ( approximated , by adding the weight of all your radio gear, motor , battery and hdwe.+ estimating the weight of the airframe.... as good as you can .... foam is usually a uniform weight / sq. ft . so you’ll be close...)

The weight(ounces) times 144 divided by the wing area equals the “wing loading “ expressed as ounces per square foot...

Some ultralight Parkflyers have wing loadings as low as 1 or 2 oz. / ft. sq. ...... My sporty PF’S are more around 4 or 5 oz. / ft sq. .... some are even in the teens , but as the WL goes UP so does the degree of difficulty in flying it also ..... more speed required to fly , higher take off and landing speeds , the threat of tip stalls at low speeds ..... so !!! keep it low , go slow ....if you want that....

Power loadings.....
Volts ( nominal 1V per cell) X Current draw ( “AMPS” , measured in series with the motor / battery ) equals .....WATTS !!!

Now divide the total number of watts by the weight (ounces) , and you’ll get the Power Loading........ expressed as watts per ounce....

Generally .... 2 watts / oz. will fly the plane .... 3 w/oz. will give mild aerobatic performance .... 4 or more W/oz. = rocket ....

so there , you can run the figures in advance and be pretty darn close as to how your plane will fly .... don’t like the figures????.... change the size of the wing and start all over.... Easy .....

Sorry Guys , this method is not as fancy as some , but has served me well for 40 + years.... Schmaybe’ if I give it a slick marketing name .....WEBOCALC ???? hahahahaa...(reprinted)Got all that ... now we'll post a new thread ...
Based on the info GPW posted, I have written a little HTML/JavaScript web page that makes this somewhat tedious (but necessary) process quick and painless. Obviously, I named it WebOCalc!

First, a screenshot:



-Flieslikeabeagle
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Old Jul 21, 2004, 01:26 PM
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Webocalc version 0.09 attached as zip file

WebOCalc's purpose is to help you get started on your scratch-built or modified model design.

As you can see from the screenshot, you have to enter the weights of all your equipment and an estimated airframe weight. Based on your plans or rough drawings, you enter your mean wing span and wing chord. You also enter your proposed battery voltage, and the estimated or measured amp draw of your motor/gearbox/prop/battery combo.

Finally, and this is very important, you choose a percentage to scale your model size up or down by. Start with 100% for this value (the orange cell, "Scale Wing Size By %").

Click the "Go" button, and WebOCalc will calculate for you the AUW, the wing loading, and the power loading. If you don't want to wade through the figures, WebOCalc will also pop up a little JavaScript window with a quick summary of the estimated flight speed and power level of your design.

Now, if the flight speed and power level work out just where you wanted, you're done. If not - go back and diddle just one number, the "scale wing size by %" number, and click "Go!" again. Keep trying until you get the wing loading you want. Lets say this happens when you're scaling by, say, 120%. Now just print out your plans scaled by the same amount - 120% - and your design is done!

Okay, I'm attaching a zip file. Unzip this someplace, and you'll find a new folder named "webocalc_javascript_version". Look in the folder, and you'll find a few files. Use your JavaScript capable web browser to open up the file "webocalc.09.html", and you should see something very close to the screenshot in my previous post. Different browsers render HTML slightly differently, so things may look slightly different, depending on what browser you use. I tested with Mozilla and Konqueror (kissing cousins to Netscape and Safari respectively).

By the way, the files are all plain text files, and *cannot* carry any virus, as they are not executables. Feel free to open them in a text editor and take a look, or run your antivirus software on them, if you wish.

I hope WebOCalc turns out to be useful to some of you scratch-builders out there. Enjoy!

-Flieslikeabeagle
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Old Jul 21, 2004, 07:47 PM
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Oops, I posted in the Off-Topic thread:

Suggestions:
Tab down the first column, then to the right column, etc...
Field for model name and notes
Field for motor efficiency, so w/oz is more accurate
W/Lb result for us old-fashioned guys
Scaled Chord result
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Old Jul 22, 2004, 02:13 AM
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Gene, thanks for the suggestions. Now where did I put my JavaScript For Beginners book???

Easy to add the motor efficiency field, also W/Lb and scaled wing chord. Auto tabbing would be easy if I knew how (!), but I can probably find out how to do it.
Didn't find time to work on WebOCalc today, I'll see what happens tomorrow.

As far as I know, JavaScript is designed to not allow writing to a file; that means there may not be a way of saving a setup for a specific model permanently to disc. I'm new to JS, so if someone else knows otherwise, please educate me! I know JS can write to cookies, and it may just be possible to put this kind of information into a cookie??? Gonna have to do a little research that one!

-Flieslikeabeagle
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Old Jul 22, 2004, 10:18 AM
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Neat program. Have you thought about a biplane or multiplane option. Also definitions of miscellaneous? Weight of landing gear puzzles me--do you have something built in for drag of LG?

Pat Daily
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Old Jul 22, 2004, 11:45 AM
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Pat, I could add a "number of wings" option to allow for biplanes and triplanes. Thanks for the suggestion.

There is no drag calculation whatsoever, all that WebOCalc does is total up all the weights and calculate wing-loading and power-loading. It doesn't even know about aerofoils! However GPW (off whose ideas this was written) says this rough method has served him well for decades, and he has the designs to prove it.

I had the impression that the landing gear is often a significant part of the total weight in small park-flier sized planes, so I added a cell for it. You can always enter '0' in any cell you don't want to bother with...I guess I should modify the program so that all cells start out with '0' in them except for the "scale by %" cell, which starts out with 100 in it.

-Flieslikeabeagle
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Old Feb 20, 2005, 07:01 PM
Rob H
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Joined Jun 2002
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Thanks flieslikeabeagl, I've just downloaded your Web-o-calc. I'm trying to be a bit more scientific this time while scratchbuilding.

Now I have to go find all sorts of data, like watts which i also have avoided knowing about so far!!!

Er.......don't suppose there's a metric Web o calc in the offing ? - everything here is measured in grams and millimetres.

Thanks again

Flyfan
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Old Feb 22, 2005, 02:30 AM
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Flyfan, I understand totally. I grew up outside the USA, and consequently, with the metric system. Since I now live in the USA, I have had to come to terms with using the extremely cumbersome, ugly, antediluvian Imperial units. But I much prefer using metric units and scientific notation, and not having to remember all those magic numbers necessary to deal with imperial units (144 sq inches/sq ft, 16 oz/lb, 64 fluid oz/gal, 5280 ft/mi, and so on. Ugh.)

When I was writing WebOCalc, I struggled with this issue for a little while and eventually decided that since the majority of RC Groups users seem to be from the USA, it would be most useful in the units most often used here. Since that time, WebOCalc has evolved a little behind the scenes, and I tried to output results in both metric and Imperial units. The result, however, is visually far too cluttered, and I am not satisfied with it enough to make it available on my website.

What I need to do is a complete redesign, with a pull-down option where you can select your choice of either metric or imperial units before you start to enter values. That will require rewriting a good portion of the program. I do plan to do this, but it may take a while...work keeps me pretty busy, and when I'm not working I'm usually trying to find the time to do all the little things that make life worth living. Not to mention I have been working on another JavaScript program to help with choosing a powertrain for electric models...it's not yet ready to release, but it's coming along!

Short version: Yes, I would like to make a metric version available, and I do intend to work on creating one.

By the way, you shouldn't need to find watts...all you need is the battery voltage, and the approximate amp draw of your motor/gearbox/prop, and WebOCalc will tell you how many watts the motor is using. The amp draw can be measured, or perhaps found in data tables on the manufacturers website. For instance, current draw for most GWS power combos can be found at the Balsa Products website, http://www.balsapr.com .

-Flieslikeabeagle

P.S. By the way, there is a newer version of WebOCalc (.12) available at my website. Go to http://flbeagle.rchomepage.com , then click on "Software", then on "WebOCalc". As I finish testing newer versions, I will upload them here. Behind the scenes, I'm working on version .16 now, but it's not ready for use yet.
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Old Apr 16, 2005, 10:13 PM
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A new version of WebOCalc is available! It's a total ground-up rewrite, with a cleaner interface and better looks. The version I've just finished is 0.2.6.

As before, WebOCalc 0.2.6 is written in HTML and JavaScript, so it should work cross-platform (Mac / Linux / Windows / Unix / FreeBSD / whatever) on any modern browser. It's been tested with Mozilla and Konqueror, as I do not use Windows and avoid Internet Explorer like the plague it is.

This version includes the option to use metric or imperial units. Also it uses some rather more sophisticated methods of estimating how your model will perform, so it should work better and be more accurate for a fairly wide range of model sizes, weights, and powers.

WebOCalc is now licensed under the Gnu General Public License, or GPL . This is the same license carried by Linux and a lot of other Open Source or Free software. In a nutshell, the progam is freely available to you to use, study, modify, or improve, with no restrictions other than one - if you make a modified version, it too must be licensed under the same GPL and made available to everyone, so that others can benefit from your work in the same way you benefited from mine. For the legally minded, WebOcalc includes links to the full text of the GPL , or you can click the link above.

You can try WebOCalc out, and download it if you like it (completely free of charge) at my RC Groups website. Go to http://flbeagle.rchomepage.com , click on "Software", then on "WebOCalc". You can try it out right there on my web page, and if you like it, you can click on a download link to download it to your computer. The download is about 500kB, mostly because of the images in the included WebOCalc tutorial.

I hope someone finds this "new and improved" version useful! (Honest, it really *is* new and improved! )

-Flieslikeabeagle
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Old Apr 16, 2005, 10:36 PM
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Here's a screenshot:
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Old Apr 18, 2005, 03:17 AM
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Quote:
Originally Posted by flieslikeabeagl
A new version of WebOCalc is available! It's a total ground-up rewrite, with a cleaner interface and better looks. The version I've just finished is 0.2.6.

As before, WebOCalc 0.2.6 is written in HTML and JavaScript, so it should work cross-platform (Mac / Linux / Windows / Unix / FreeBSD / whatever) on any modern browser. It's been tested with Mozilla and Konqueror, as I do not use Windows and avoid Internet Explorer like the plague it is.

This version includes the option to use metric or imperial units. Also it uses some rather more sophisticated methods of estimating how your model will perform, so it should work better and be more accurate for a fairly wide range of model sizes, weights, and powers.

WebOCalc is now licensed under the Gnu General Public License, or GPL . This is the same license carried by Linux and a lot of other Open Source or Free software. In a nutshell, the progam is freely available to you to use, study, modify, or improve, with no restrictions other than one - if you make a modified version, it too must be licensed under the same GPL and made available to everyone, so that others can benefit from your work in the same way you benefited from mine. For the legally minded, WebOcalc includes links to the full text of the GPL , or you can click the link above.

You can try WebOCalc out, and download it if you like it (completely free of charge) at my RC Groups website. Go to http://flbeagle.rchomepage.com , click on "Software", then on "WebOCalc". You can try it out right there on my web page, and if you like it, you can click on a download link to download it to your computer. The download is about 500kB, mostly because of the images in the included WebOCalc tutorial.

I hope someone finds this "new and improved" version useful! (Honest, it really *is* new and improved! )

-Flieslikeabeagle
Hi, FLB.

I tried the new and improved version on my Mac, in both Safari and the dreaded IE 5.2 for Mac, and could not get it to work in either one. I went back to the earlier version and had no problem. Any ideas? It looks pretty nice. I really would like to use it. Thanks,

Barry
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Old Apr 18, 2005, 09:17 AM
Rob H
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I downloaded it too and can't get it to work - I get the choice of Metric or Imperial and when I click on either, nothing happens. I went to the html folder and opened Metric Ok , entered data but no processing.

It's probably just a minor thing. I like the option to be able to just scale the info and get new results.

Hope you can fix it up, flieslikeabeagl

Flyfan
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Old Apr 18, 2005, 10:21 AM
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Quote:
Originally Posted by Flyfan
I downloaded it too and can't get it to work - I get the choice of Metric or Imperial and when I click on either, nothing happens. I went to the html folder and opened Metric Ok , entered data but no processing.

It's probably just a minor thing. I like the option to be able to just scale the info and get new results.

Hope you can fix it up, flieslikeabeagl

Flyfan
Yeah, you click on calculate, and it doesn't. Hey FLB, are you thinking of getting a job at MS?

Barry
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Old Apr 18, 2005, 02:43 PM
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Sorry you're having problems, guys. Blowentw, bite your tongue when you make cracks about me working for MS!

I think the problem is that the new version of WebOCalc uses a lot more CSS and JavaScript features than the old one in order to make it look better than the old version. IE 5.2 is horrible at supporting CSS and JavaScript standards - as usual, the MS guys inserted non-standard versions of standard protocols in the hope of preventing any other browsers from succeeding in the marketplace. Internet Explorer is also the most insecure browser available today, having taken over from Microsoft Outlook as the worlds leading virus / adware /spyware / worm / trojan / phishing / website spoofing vector.

I've tested the new version of WebOCalc in Konqueror (Apple's Safari is Konqueror with slight modifications to run with the Mac OSX GUI), Mozilla 1.7, and Firefox 1.0.1, and it works fine in all three. I can only guess that Safari is based on a much older version of Konqueror than is currently available in the Linux world. I haven't used Windows in three years, so I haven't had a chance to test WebOCalc in Explorer.

I will try and put out a crippled version of WebOCalc to work with older crippled browsers soon, but in the meantime why not try a modern, totally Free, very good browser first? Go to http://www.mozilla.org/ and download and install Firefox 1.0.3. Edit: I should have said, download and install the newest version of Firefox. As of august 2005 it's up to version 1.0.6. It's available for Windows, Mac OSX, and Linux.

Try out WebOCalc with Firefox, and let me know how it goes. Whether or not you like WebOCalc, I'll almost guarantee that you'll like Firefox (standard features include tabbed browsing, the ability to block pop-ups and images from ad servers, sophisticated cookie management, etc, etc).

I downloaded WebOCalc off my website, unzipped it, and ran it in Konqueror just now to check. It seems to work just fine in Konqueror...here's a screenshot.
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Old Apr 18, 2005, 03:03 PM
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I'll second and third the Mozilla and FireFox options. I have been using Mozilla for some years now. Yes, there are some websites that use the M$ corrupted standards and don't work well in other browsers - I consider those to be the product of brain-dead webmasters. Any webmaster worth his salt would be using international standards in his web programming to allow for the maximum user accssibility - not promoting M$ product and domination.

Anyway... Thanks for WebOCalc... Nice little tool.

J.P.
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