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Us "WattFlyer"s could start a database on what Amps specific Prop/Motor combos draw

Old 05-04-2006, 03:25 PM
  #1  
DerGoetz
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Default Us "WattFlyer"s could start a database on what Amps specific Prop/Motor combos draw

I was running some tests and writing down some numbers this morning on my new setup....and it occured to me:


There are enough of us to start a "who-is-who" of Motors.
Since I am not running the site I wouldn’t be able to determine a "standard" for contributing data neither would I be able to collect and present the findings of us WattFlyers, but I think if a lot of us supply data that tells what prop (e.g. APC 14*10) on what motor (Axi 4120) on what power setup (6s) draws how many amps, that database would not only help those who do not have any software to calculate the power-layout of their next investment (new motor, new batt-pack, new prop, new plane), but it would give us real-life data instead of theoretical data via software.
Plus we might be able to attract more visitors due to this "Killer Application".
Keeping it at amps would make it possible for a lot of us to contribute, thrust, rpm etc are for the more advanced crowd but I bet the mods could incorporate that in a database as well, if supplied.


What do you guys think?
Yes, the first few weeks would be hectic of course, but after that it would be quite manageable for mods to keep up with the posts and it would be a great dictionary for all.




Goetz
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Old 05-04-2006, 03:33 PM
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bsoder
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The biggest problem you run into is measuring - what standards do you use? Also, elevation, temperature, and to some extent humidity all are factors.

For example - I use Dr. Kiwi's motor data as a good starting point. If you're not familiar with it, check RCG in the Power Systems section, he's done motor tests on a LOT of different motors. For me, his thrust and amp numbers are always high - he lives at ~600 ft elevation, in Lousiana if I remember right. I'm in Arizona, at 1450 feet, it's higher, drier, and hotter here generally. My amp and thrust measurements are around 10% lower than his.

If they're going to try to create a database here, they need to take those environmental standards into consideration.
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Old 05-04-2006, 03:39 PM
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DerGoetz
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Hahha...I see.
Yeah, just an idea. You would never get precise numbers that apply to everyone. But then again, I bet no-one complains the way we do about everything when they buy their new car and the HP's aren't exactly the same since they live as high as Dr. Kiwi lives. Living in different areas and therefore getting different results with a lot of techincal equipment is just a fact of life and I think most of us got used to that by now, especially when it comes to cars and their supposed ratings.

I just thought it would be cool to have a database that all of us help build (hey, if wikipedia can do it...) that guides in buying equipment. Instead of asking the same questions over and over (hey, who runs a 2808 on...) have a sticky or a seperate database that has some rough data in it.
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Old 05-04-2006, 07:36 PM
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On RCU there is a product guide that lets you do some comparisons, view specs and other cool stuff. I wonder if we could adapt some user test data into this somehow?

Here is an example...the database of motors/esc needs to be beefed up a bit I'm sure.

Click the tabs at the top to see data on this product once you are on the page.

http://www.rcuniverse.com/product_gu...?engine_id=972

http://www.rcuniverse.com/product_guide/engineguide.cfm

This system makes it easy to find things and extract data as it is very relational. To do what you are suggesting probably isn't an enormous leap to adapt this a bit. Some pieces of the product guide were originally devised to do what you suggest but we fell short in development time and never got to that piece or scoping out how it would work/look.
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Old 05-04-2006, 09:00 PM
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I think as long as you have some of the important things included in your ratings it would be a help to relative newcomers to eflight in general.

typically I use model weight, wing area, number of cells, motor size, prop size, amps, and a very important piece of information is prop rpm.
if you power a say 40 size model, and your conversion is approximately the same weight as the glo version, and you swing the same size prop at the same rpm, then watts become somewhat irrelevant. ( except for bragging rights)
watts can be converted to actual power, or they can be dissipated/used by creating heat, so ,measured watts is not always the best way to measure power out of a system....that's why prop size and rpm have to be factored into the equation.
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Old 05-24-2006, 05:49 AM
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jdetray
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Before getting much farther into this, you might want to check The Great Electric Motor Test to see if it already does what you're discussing.

- Jeff
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Old 05-24-2006, 02:00 PM
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Mike Parsons
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Marc,
I would love to adapt something like that here.
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Old 05-24-2006, 02:24 PM
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Geoff_Gino
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Originally Posted by Mike Parsons View Post
Marc,
I would love to adapt something like that here.
I think this could work. I am a pure 100 Watts/lb believer and usually take the manufacturer's recommendation for the prop. This has led to me having lots of obsolete props lying around as I usually prop up from the recommended prop to get the current draw I am looking for.

Perhaps the database could serve as a starting guide for a particular motor for the rest of our members.

e.g. Thunder Tiger Soaring Star, AUW 1,7 kgs, 3S1P Kokam 3,5 amp, Hyperion 3205, draws 37 amp swinging a 10x8 Cams folding prop.

I have 2 unusable props left over before I found this combo.
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Old 05-24-2006, 02:32 PM
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If anyone is interested I have a data sheet that I use. It is an Excel spreadsheet with all my calc's that I need on the sheet.

PM me with your e-mail address and I will send it on.
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Old 05-24-2006, 02:34 PM
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vax6335
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also list esc's used with the your setups
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Old 05-24-2006, 08:20 PM
  #11  
redgiki
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One thing that might be helpful is to build a database of planes that have been electrified, and then list available power setups with amp draw, voltage, ESC used, and performance (static thrust in ounces, unlimited vertical in flight, etc.)

Paul Bradshaw recently distributed a flyer at an electric fly-in in Utah describing all of his setups in detail, with flight time, performance notes, etc. He flies some really BIG electrics, and for those looking to get into that arena it's nice to just imitate what already works.
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Old 05-24-2006, 09:20 PM
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Steve over at slofly.com started a brushless motor database, I think last month or so. You can take a look at what he has started already at:

http://www.slofly.com/brushlessdb/
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