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Old Jan 24, 2015, 05:48 AM
Weltherrschaft will be mine
Germany, SN, Leipzig
Joined Nov 2012
319 Posts
if it uses the same mosfets as the 911 , which i believe it does it should handle 2 8mm motors...... need to try to verify. it handles 2 7*20 motors well.

hu, need to get those items via bg, too. plus some 150 and 2oo mah v911 batts.
yust realized one of my spare 939 boards does not bind... unpacked it yesterday, but bought it 4 month ago..... should i bother bg for 10 euros, my 939 wing and fuze also arived crashed, but i thougt 5 euros are not worth the hassle back than
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Old Jan 24, 2015, 08:24 AM
Faroe Islands/Germany
epilot's Avatar
Joined Nov 2000
6,049 Posts
I disagree with Borkencorter. 2x8.5mm motors can pull close to 4A and I doubt the FET will handle that. Either it will blow or it will fail to deliver enough current to the motors. I would say that 2x7mm motors is the safe limit. Best thing to do is to check the actual current before connecting anything to the brick.
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Old Jan 24, 2015, 01:58 PM
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Joined Feb 2014
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OK, I'll try to get a reading with just a single 8mm motor. What is the board's amp limit - 3A? Anybody tried stacking a 2nd FET for more amps?

I may also try using a 8x23 SCS motor if I get a spare between now and when the board arrives (late next month at best) What amps does the 7mm motor pull and what is its thrust?

I guess what I'd most like to know is what is the maximum thrust by using all available amps through the board, and how to get there with the least weight. I assume most of you are interested in the same. The primary plan for my first board is a single motor hovercraft for a smooth gym floor.
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Old Jan 24, 2015, 03:22 PM
Faroe Islands/Germany
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Joined Nov 2000
6,049 Posts
How long is a piece of string? There are lots of different 7mm motors and lots of props out there.
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Old Jan 24, 2015, 03:28 PM
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Joined Feb 2014
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Quote:
Originally Posted by epilot View Post
How long is a piece of string? There are lots of different 7mm motors and lots of props out there.
Le'ts start with the 2 you recommended as OK. I've read that most of these pager motors are very similar in construction, but your point is valid. So if you can point toward info on something that works, charts, etc. that would help. Might even be good to have a post here collecting that kind of info?
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Old Jan 24, 2015, 03:35 PM
Faroe Islands/Germany
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Joined Nov 2000
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Have a look at this thread:

http://www.rcgroups.com/forums/showt...otor+prop+test
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Old Jan 24, 2015, 04:02 PM
Registered User
Portugal, Lisbon
Joined Oct 2006
67 Posts
Have you experimented with v911 servos? Do you know if they can be modded for continuous rotation? I have done it to SG90 servos but I have not explorer v911's (I have one comming from banggood right now).
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Old Jan 24, 2015, 05:56 PM
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Joined Feb 2014
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Quote:
Originally Posted by epilot View Post
Great! Thanks. That's a much better answer than ~20g for the 7s.

Unfortunately I didn't find any F929, F939, or F949 posts but they aren't quads, either.

I'd also be willing to bet when someone orders a 929/939 or similar coreless motor it could come from any of dozens of small shops in China so even the good baseline testing is only as good as the samples tested and relates most directly to the amount of stock on hand from when and where it was purchased.
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Last edited by GottaZoom; Jan 24, 2015 at 06:01 PM.
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Old Jan 25, 2015, 09:56 AM
Don't cut the Yellow Wire
dr.E's Avatar
Ridgewood ,NJ
Joined Jan 2000
3,590 Posts
Would you be able to convert the board to use a brushless outrunner.. (1gram esc, 1 gram motor)

It would just be a matter of getting the signal before the board's esc
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Old Jan 25, 2015, 05:55 PM
Registered User
United Kingdom, England, Redcar
Joined Jan 2006
3,298 Posts
Another couple of foam gliders to add to the mix , sorry just adding to remember as much as show.



http://www.aliexpress.com/snapshot/6...65573841727375

Price is just around $16 delivered so not prohibitive.

The other is a multiplex fox clone which cost a little over $8 delievered

http://www.aliexpress.com/snapshot/6...65573841717375


Both hve been ordered and i will post back when they arrive , they will join the air rider and will be converted once i get the use of fingers back properly , it no fun typing with my ear
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Old Jan 25, 2015, 07:42 PM
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USA, SC, Charleston
Joined Oct 2002
490 Posts
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once i get the use of fingers back properly
Oh, no! What happened, if I may ask?

Rick
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Old Jan 27, 2015, 11:31 AM
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United Kingdom, England, Redcar
Joined Jan 2006
3,298 Posts
Nothing nasty unfortunately , i love a bit of blood and gore , damaged a nerve in my neck which is nothing major but has resulted in a nasty "twitch" in both my shoulders and pins and needles in my hands , physio for a while and maybe a little surgery if necessary , just one of those things , probably my own fault from loving the bmx a little too much when i was a kid

Hoping it will all be gone in time for our British "summer"

ty for asking
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Old Jan 27, 2015, 05:20 PM
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USA, SC, Charleston
Joined Oct 2002
490 Posts
Ouch! So sorry to hear that. I've got nerve damage going into my arm, and it makes me quite the grouch sometimes. Next time around, you might want to get an R/C dirt bike.

That "British Summer" is probably about like the "South Carolina Winter" I'm ...uhhh... suffering through.

Rick
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Old Jan 29, 2015, 05:57 PM
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Joined May 2005
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I need some advice. My fingers are fat and clumbsy and sort of unco-ordinated. The airplanes and parts are small and the batteries are located in tight spaces. I do my best damage trying to separate the battery from its airframe connector. What do people use in these circumstances? Padded needle nose pliers? Plastic tweezers or a special ejector tool?
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Old Jan 29, 2015, 06:59 PM
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United States, WV, Charleston
Joined Jan 2014
112 Posts
Quote:
Originally Posted by epilot View Post
How long is a piece of string? There are lots of different 7mm motors and lots of props out there.

Judging motors by their physical dimensions is meaningless. Granted, longer (or larger) motors will generally have more torque, but that's all that can be inferred.
The WINDINGS on the armature are what determines the characteristics of a given motor (the number of turns of wire, and even the wire size itself), assuming magnetic strengths. What's needed is specific information on individual motors, and their designation by the manufacturer. Knowing the given Kv ( RPM per 1 volt applied in a no-load situation) is a great help, too.

Just saying an XD x XXL is useless.
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