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Electric Shock

Motor and esc selection

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Keith De La Mare29/06/2007 20:04:00
4 forum posts
Hi

I have just recieved a Precision Aerobatics Electric Shock as a present along with servos motor and esc, can someone please advise me on the compatability of the motor and esc which is a Jamara AL-M1048 and a Jamara Magnum esc BEC 16 amp Reoler.
Also the size prop I should use on this set up.

Kind regards
Keith De La Mare
Alistair Taylor02/07/2007 09:05:00
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601 forum posts
18 photos
See; http://www.alshobbies.com/shop/lookupstock.php?pc=4677&Desc=&PHPSESSID=bb0b4283907441a7ca9110d16095f242

Exclusive to Al's Hobbies.

This new range of Jamara Brushless Outrunner motors are a direct replacement for the AXI 22xx series motors,but with more torque due to longer magnets.

Supplied complete with 3.5mm gold bullet connectors plus radial motor mount as standard.

Equivalent to AXI 2208/26 Ideal for indoor/park flyers up to 500g

Specs:
Weight: 43g
Cells 2-cell Li-Po
Prop size: 9x4.7

and;

http://www.jamara-modelltechnik.de/product_info.php/info/p1361_AL-M-1048.html


the following discussion (apologies for directing you to another forum) is what you can get when people who don't know the motor try to advise. It is capable of 20amps according to Jamara, but on 3S lipos you will probably want to reduce the prop size to 8x4 (8040 in GWS speak);

http://www.wattflyer.com/forums/archive/index.php/t-2671.html

HTH

AlistairT
Keith De La Mare02/07/2007 12:31:00
4 forum posts
Thanks Alistair

I'm still a bit confused but according to the spec on the esc (roughly translated, its not in english) it say's 2 to 20 amp so I think I may be ok.

KeithD
Alistair Taylor02/07/2007 14:33:00
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601 forum posts
18 photos
Make sure the Lipo batteries can deliver at least 20 amps.

AlistairT
Erfolg02/07/2007 15:13:00
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11750 forum posts
1337 photos
Keith

Alistair’s statement about making sure that the battery can deliver 20 amps may need extra information if you are new to electrics.

Lipo batteries are generally specified in mill amps, that is amps to the power of 10-3 or 1/103 (however you like to write these things). Therefore if you see a battery classed as 2000mA, it can also be described as 2A. If the battery is classed as 10c, this is meant to tell you that you can discharge the battery up to *10 the stated ampage. Therefore our 10c, 2A, battery can be discharged up to 20A. If it were 20c, then the sum becomes 2*20=40A. Easy is it not.

In the case of NiCads, people seem to abuse them with little problem.

It is worth noting that the general common consensus at the moment, suggests that the harder you push your Lipos, the greater is the need to get the cells balanced during the charging process. I personally always use a balancer when charging, and they are cheap, approx £15.

The problem with batteries, there are more myths and stories surrounding them, than the combined tales of Aesop and the Brothers Grimm. Some have a bit of truth, but suitably embellished to act as a warning and to sell more of the RIGHT Products.

Regards
Erfolg
Keith De La Mare03/07/2007 18:39:00
4 forum posts
Erfolg

Thanks for your reply, it has helped me to begin to understand as I am new to electric flight.

So my 800 mah 20c LiPo has a discharge of 16A.

My next problem is deciding on the size of battery for the electric shock flier, this needs to have enough power and be as light as possible, sounds like I am going to have a trade of somwere here.

This choice is further complicated by the fact that all the jargon on the back is in German, unfortunatly not my strongest subject back at school.

I'll list the details here just in case someone can help.

Windungen 28
Spannung 7-12V (I think I get this one)
Umdreh Pro Volt 1048
Innenwiderst 165 mOhm
Leerlaufstrom 0,57A
Stro beimax Wirk 3mm
Freie Welle 10mm
Durchm./Lange/Gew 28mm 26mm 43g

Many thanks
Keith
Alistair Taylor04/07/2007 13:24:00
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601 forum posts
18 photos
Windings: 28
Current: 7–12 V
RPM: 1048
Resistance: 165 mOhm
Low load current: 0,57 A
Current by max effic.: 5–10 A
Shaft Ø: 3,0 mm
Ø: 28 mm
Length: 26 mm
Weight: 43 g
Erfolg04/07/2007 16:21:00
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11750 forum posts
1337 photos
The only bit not delt with is

Freie Welle

which I think is a a 10mm diameter spigot

I was thrown by the shaft diameter, I expected a Durchmesser and a Schaft or Spindel. It only goes to show, that you need to learn yet another new language when things are of a techniacal nature.

Some of the information is generally only useful if you have a software package which matches motor details to propeller sizes etc.

I am sure that Alistair's help will have useful and hope that my own has not confused you.

Best luck, modern electric packeges normall work very well and are not as difficult to master as the jargon suggests
Regards
Alistair Taylor05/07/2007 10:04:00
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601 forum posts
18 photos
Life was so much easier when a thingamagig was a thingamagig, and a whojamaflip worked perfectly with a whatchamacallit.

:)
Keith De La Mare05/07/2007 19:17:00
4 forum posts
Many thanks that does help :-)

Keith
Alvin Espley17/07/2007 16:00:00
39 forum posts
i have just bought a HET super tucano from the overlander stall at cosford,does anyone have any experience flying this model using nimh battery's? cos the pack i was given is a tornado 3300 nimh pack weighing 515 grams just seems a bit heavy for a 1 meter model
Alistair Taylor18/07/2007 11:52:00
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601 forum posts
18 photos
I built the 45" tucano (one and a bit metres) from plan.

I've used 8-cell packs in this with good results. They are heavy, and the plane has a more steady "sit" in the air, but flies fine.

If you're really concerned about the weight buy one or two CP1700 NiCad packs. These (obviously) don't last as long, but are lighter, and "punchier" (happier delivering high amperages) than the 3300 NiMHs.

Test fly it on these and see what the launches are like on the motor you have. If it wrenches your arm off and goes vertical like a homesick angel, you'll probably be OK with the 3300s. Ideally get someone else to handlaunch for you so you have both hands on the sticks. NB - Electric motors don't suffer from fuel surge on launch :)

AlistairT
Alistair Taylor18/07/2007 12:04:00
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601 forum posts
18 photos
OK, I had a look at the Super-tuc.

How well it will fly or not with that battery pack will depend on the motor and prop you are using.

With the heavier battery pack you will need a prop/motor combination that delivers 300 watts or more (approx).

What motor do you have lined up for it?

AlistairT



Alvin Espley18/07/2007 13:33:00
39 forum posts
hi alistair thanks for the reply, the motor i am thinking of using is a brushless bm2409-12 out runner the guy on the overlander stall recomended a apc7x5 prop
Alistair Taylor18/07/2007 13:45:00
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601 forum posts
18 photos
Sounds good.

I bent a couple of motor shafts using this motor and prop combo on a belly-lander, which was cured by using a prop saver. This may not be a problem with a glider (which flies slowly enough for the prop brake to work), but if it is, just get a saver.

Shafts are only 50p each anyway.

AlistairT :)
Alvin Espley18/07/2007 22:38:00
39 forum posts
thanks for the info .the model is almost finished ,will let you know how it goes fingers crossed ..

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