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Old Oct 20, 2010, 02:38 AM
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Romania, Dolj, Craiova
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Sure, I understood all the above, and my initial post don't want to sounds offensive, just my desire for improvement. As usual, the language barrier...
Time to contribute, then
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Old Oct 20, 2010, 10:23 PM
Got shenpa?
flieslikeabeagle's Avatar
Los Angeles
Joined May 2004
10,940 Posts
No worries, Renatoa. Your English is very good, better than some native English language speakers I've met here in the USA. As for me, I don't speak a single word of Romanian, or any of the other languages spoken in your part of the world. So without your English, we would never have managed to communicate at all.

Did my post help at all? I'm hoping you're now a WebOCalc wizard, and can confidently use it to power most models you come across.

I understand the desire for improvement, especially with software - there is always something that could be done better, or something new that could be added. One thing I'd like to add to WOC myself is a little "go direct drive" button that would pop up next to those propellers that happen to have nearly 1.0:1 gear ratio; click on it and the program would show you what to expect with that particular propeller in direct drive. No need for todays manual trial and error method.

I've had that idea for some time, but the program code needs to be cleaned up before that new feature can be added. WOC version 1.7 (which is almost complete) implements most of the code clean-up, so it would be a good starting point for the next step forward.

-Flieslikeabeagle
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Old Oct 27, 2010, 12:28 PM
This is kid stuff.
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USA, AR, Harrison
Joined Aug 2010
816 Posts
Just want to express my gratitude for, and appreciation of the WebOCalc software. I'm embarking on a stick/tissue airframe rubber to electric RC conversion with some measure of confidence and even eagerness thanks to the powertrain selection assistance of WebOCalc.

You're a good man, beagle. I hope I have a chance to buy you a drink sometime.
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Old Oct 27, 2010, 04:50 PM
what goes up...
ezrydr's Avatar
Alton Iowa
Joined Aug 2006
423 Posts
Well MR FliesLikeaBeagle good to see you still visit the forum now and then!! I hope you know how much I appreciate all your efforts with WebOcalc!! It's the most useful piece of software I've run acorss for this hobby.
I tried the MotoCalc and even paid for it but I think it is clumsy and hard to interpret. I downloaded your last version and burned it to a CD so I have a permanent copy. As long as I'm flying electrics it will be my go to software!
Hope you are well! We miss you on the forum!

Steve
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Old Oct 30, 2010, 03:07 PM
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Romania, Dolj, Craiova
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Quote:
Originally Posted by Swissflyer View Post
Hi Renatoa,

I see that Dr Kiwi, very well respected on RC Groups, also put data on the KEDA TR2837 / 08 into DriveCalc. It is not as efficient as an AXI but should give you a healthy 640g of static thrust at a pitch speed in line with WebOCalc using a 2S LiPo.

The KEDA TR2837 / 10 will give you a pitch speed of 95 km/hr with an APC 7x5 on 3S, that would be throwing a lot of energy away in the slipstream when you only need a pitch speed of about 68km/hr

Of course it is your choice but do read the wise comments of Chuck & FB on this thread.

I would love to know how it flies

Mark
Beautiful ! Thank you !
Maidened it today...
Hard to acheive a good CG, ended with 2000 mAh packs and almost 100grams of lead... this thing really was designed for a heavy pack in the nose.
But, once balanced and trimmed, sky is its realm, hard to descend. And today was dead calm, I can't imagine how will be in a good thermal day !
Must keep throttle low, over 2/3 the thrust is too big, and it violently dives.
Same happened to me at a launch, when a fellow push full throttle, was very close to slip the plane into the ground.
I think 2s will use better the full throttle range.
Used a 3 blades foldable 7.5*4 prop.

I'll try to make a movie tomorrow.
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Old Nov 03, 2010, 04:03 AM
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Brigerbad, Switzerland
Joined Sep 2004
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Great

Quote:
Originally Posted by RENATOA View Post
Beautiful ! Thank you !
Maidened it today... I'll try to make a movie tomorrow.
Very good news and thanks for the update. Very interesting comment about the thrust line.
I look forward to the movie
Mark
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Old Nov 07, 2010, 10:24 AM
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Joined Jun 2008
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Biplane calc in WebOCalc

Newbie here. Read the first two pages of this thread and used WebOCalc with the author for his examples. I think I get most of it. I thought I would run it with data from a ARF biplane I am thinking about getting, Electrifly Tiger Moth. From the manufacturer, the weight, wingspan, and wing area are 8.1oz, 30", and 282". When I plug these into WOC and click "Run Prop Size Wizard" I get nothing....In playing around with the numbers, I find that if I give it a wing area of 257" or less it does work. But if I put in 258" or higher, it doesn't work.

I'm guessing it has something to do with it being a biplane, but really don't know. Is it maybe a bug in the program?

I did find that if I used 282 and said the wingspan was 60" (both of the biplanes wings) I did get some numbers.
Is this the way I should use it when configuring for a biplane?

Thanks for any help
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Old Nov 07, 2010, 10:44 AM
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Quote:
Originally Posted by aclinml View Post
Newbie here. Read the first two pages of this thread and used WebOCalc with the author for his examples. I think I get most of it. I thought I would run it with data from a ARF biplane I am thinking about getting, Electrifly Tiger Moth. From the manufacturer, the weight, wingspan, and wing area are 8.1oz, 30", and 282". When I plug these into WOC and click "Run Prop Size Wizard" I get nothing....In playing around with the numbers, I find that if I give it a wing area of 257" or less it does work. But if I put in 258" or higher, it doesn't work.

I'm guessing it has something to do with it being a biplane, but really don't know. Is it maybe a bug in the program?

I did find that if I used 282 and said the wingspan was 60" (both of the biplanes wings) I did get some numbers.
Is this the way I should use it when configuring for a biplane?

Thanks for any help
WebOCalc continually eveolves, and yep, you may find the occasional oddity like you did. Beagle is aware of this actually and is working on the next version.

A good starting point with any plane is simply to pick a max prop size of about 25% of your wingspan, which in your case would be about 8".
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Old Nov 07, 2010, 10:51 AM
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Here ya go, a nice slow sport flying bipe with a thrust to weight ratio of about 1:1, and just barely sipping power from a 2s Li-Po.

Chuck
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Old Nov 07, 2010, 11:22 AM
what goes up...
ezrydr's Avatar
Alton Iowa
Joined Aug 2006
423 Posts
nice one Chuck

I ran it for him too, just for fun

here's what I got...I used a 3s lipo

might be hard to find a 580kv motor tho

interesting that in either case the prop called for is the same

beagle did a great job with this software. Glad to hear he's updating it.

BTW - I find it works best wirh FireFox.
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Old Nov 07, 2010, 11:27 AM
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Nice job! And that's all I use is FireFox. MSIE drives me nuts.
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Old Nov 07, 2010, 05:41 PM
Curiouser and curiouser
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Rochester, NY, USA
Joined Oct 2005
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Using what I have?

Great thread!
WOC is nicely done, too.
Here is my WOC output in the attached photo - it is based on what I have - except the props available in WOC don't seem to include mine. Mine are mostly lower pitch props.

Here is what I have:
A desire to get my 5 oz. camera aloft.
A Honda Civic with a trunk opening of 42".>> Trainer One style wing 42"
A four cell A123 battery 11 ounces - four cells allows me to trick my cheap ESCs into thinking that they see a three cell LiPo for a better LVC.
Two BP-21 brushless motors - Kv=1400 -- two because I want the camera in the center pointing forward.

So I put that data in WOC and it gives me props that I think should be more like 10 x 3.8. None get close to a gear ratio of one. And I think that using the 8x4 is way to whimpy. Looks to me like a GWS 8 x 4 would probably be better than the APC 8 x 4 but maybe that isn't in the data base.
Playing around with the parameters I have not been able to find any props that have a pitch/diameter ration of less than 0.5.
Is there any way to see what props are in the data base for WOC.
Adjusting the max current doesn't help and I am stuck with the Kv of my BP-21s.
Any suggestions?

Walt
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Old Nov 07, 2010, 05:50 PM
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Originally Posted by wjbite View Post
Great thread!
WOC is nicely done, too.
Hi wj,

Are you able to work out the reasoning at the beginning? I'm really glad you're enjoying it!

Chuck
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Old Nov 08, 2010, 01:48 PM
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Quote:
Originally Posted by NoFlyZone View Post
Here ya go, a nice slow sport flying bipe with a thrust to weight ratio of about 1:1, and just barely sipping power from a 2s Li-Po.

Chuck
Thanks, Nofly.....I have a followup question. For comparison, the plane I am looking at is the Great Planes Electrifly DeHavilland Tiger Moth.

They recommend their own 1750Kv motor. If I plug that into WOC, most of the numbers stay the same except for the prop values. It looks like the prop that is closes to a 1:1 gear ratio, would actually have a bit less thrust (6.8) compared to a 970Kv motor. Are there any other advantages in choosing their motor over the 970 you recommend?

Thanks again.
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Old Nov 08, 2010, 01:58 PM
Curiouser and curiouser
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Rochester, NY, USA
Joined Oct 2005
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Quote:
Originally Posted by NoFlyZone View Post
Hi wj,

Are you able to work out the reasoning at the beginning? I'm really glad you're enjoying it!

Chuck
Thanks for the reply, Chuck.
Yeah, I think I understand the flow of it all.
My real question buried in that long message is:
is there some way for me to see what the list of props are that is in the data base - if my props are in there then I should forget trying to use them. But if they are not in the data base maybe a lower pitch prop will get me to a 1:1 gear ratio (I think that is what I need for brushless motor).

Walt
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