Slo-V Flyer

Yeah $100, hell if it even works for 15 minutes I think it's probably good enough to beat around the yard with. But wow that's a BIG esc.... I'm thinking it's one of those surplus deals where they had old ESCs laying around and so they decided to sell them off cheap... maybe.

Access

Here's the easiest way to model it. Remember that a typical brushless motor consists of three coils, and a magnetic rotor. That's really all you need to know.

1) The torque the motor can generate (from rest) is related to the magnetic field any coil can generate. Magnetic field strength from an electromagnet is directly proportional to the turns * current. So more turns (lower KV), or more max current will mean a greater max torque from rest. Likewise lower KV means more (low-rpm) torque can be provided per unit current draw.

2) At some point ~2tesla, or possibly less (depends on the construction of the coil, the core, the wiring, etc.), the coil can't produce any more magnetic field -- this is known as the saturation point. The high limit on torque is ultimately based on the area of the coils, rotor, etc., meaning the amount of mechanical power any given motor can produce is ultimately a function of the RPM it is spinning at.

3) The motor's coils have some inductance, and hence impedence which is related to the number of turns. At low RPMs this is largely irrelevant, as the RPMs increase this will start to affect the ramping up of current to each coil and hence limit the max torque. How quickly the max torque falls off as RPM increases is based on voltage and KV. A higher voltage, or a higher KV means the torque falls off slower as the RPM increases, hence a higher RPM limit and more torque at the higher RPMs.

4) The motor's coils have some resistance, though typically not much. The ESC also has some resistance. Either way higher voltage generally makes the system more efficient, ie. a 10V, 4000KV system will run more efficiently (cooler) than a 5V, 8000KV system, and it will have a greater max power output. As the size/weight of the system increases, higher voltages are typically used for this reason. A good portable power drill runs off 18V. Some of the larger scale electric aircraft run off ~50V. Hybrid or electric cars typically in the 100-400V range.

ashunte

ok,ok hey matthew when you get the set-up can you give us normal guys an eval? for 100 bucks is it fast and does it work cause i just wanna bash with less motor replacement or rebuilding! thanks!( i hated science!)

Matthew007

Access..I think we've moved on.

Slo-v, looking at the video with the same setup, it looks good.

3300kv is not that much of a big deal.

Also, the motor is the same as pede's redcat setup and another guy on a traxxas forum who got his rusty to do 39mph on 6 cells, he claims with a radar:
[link=http://monster.traxxas.com/showthread.php?p=3109568#post3109568]forum thread[/link]

However, the redcat setup has a 75A esc, this one has a 70x55mm 120A..so we'll see.

I don't think 70x55mm is that big at all, I think you guys are looking at the pic with the guy holding it. He might be a little asian man so it probably looks big..no offense to anyone.

I'de rather have a bigger esc because it will dissipate heat better and it would be easier to mount a cpu fan on it in case you'de need it.

tashspop, no I did not get it yet because I ordered around Christmas and it comes from China. From the 10 they had, they have 2 available now so you can contact those ebay members in a few weeks and ask their opinion too.

As for me, I'm going to test it with a 2100mah nimh 7.2 radio shack, 3300mah nimh 7.2 radio shack, 3000mah 8.4v generic hump (if I can fit it) on a Tamiya F-150 with full bearings, two ball diffs, aluminum motor mount, aluminum main shaft, and 16T,17T,21T,24T pinions...if TH ever ships the damn truck.
I asked if it comes with a dean, tamiya, or none connector to the esc. Then I'm going to wait and see if I can mod the chassis to fit 8.4v or if the truck can even handle it. AND then i'm going to order and test a [link=http://www.all-battery.com/index.asp?PageAction=VIEWPROD&ProdID=1830]Tenergy Propel 4500mah[/link]
Free ship with codes from http://www.retailmenot.com/view/all-battery.com
"# Continuous Discharge Rate: 10C ( 42Amps)
# Bust Rate: 20C (84Amps) " should be enough.
Either 6/7c and either dean/tamiya until I get the ESC.
Charger im using is a duratrax piranha ac/dc 2.5A timed, im going to use a voltmeter to baby sit it until -delta V.
P.S
My multimeter only goes up to 10A and only safely for 10 seconds..so that sucks.

snellemin

I bought one for the heck of it as well. If it can take the abuse as the mamba esc, I'll be happy. Looks like a common esc format designed for a plane. Has a low max amp rating, but won't matter much with low kv motors. I guess I'll sell the motor for 30 bucks when I get it in.

Matthew007

Why sell the motor, what's the point of getting the ESC with it? Even though it's 3300kv it can handle a lot of cells supposedly, but judging from the videos, even on 7.2v it seems so torquey that you can just use larger pinions.
I'de test it first.

snellemin

hmmm the point...I allready have a much better 3350kV motor. I just want to try the ESC.

Slo-V Flyer

I run a 2700 kv Feigao 9L in my Rustler, and even geared 25/84 I can pull rolling wheelies all day long on 3s topping out just around 40 mph, and with 6-cell Dtx 3800 I get decent speeds a hair over the stock 20T Stinger but with low temps and good torque.

snellemin

I do rolling wheelies as well with 78/35 in my rustler running 5s1p A123 cells with an 8L motor + 3.5" tires. Its just nuts controlling all that power, but gets my heart pumping.

Matthew007

Wow I just got it. Pics soon. My main cam fried so sorry if the images suck. Im getting a new cam monday.

[link=http://www94.megaupload.com/files/dde78c1c9fd034041f69aa48e9051039/PHTO0004.AVI]video of Program Card[/link]

[link=http://www.modellfun.com/ebay/MFC_manual_en.pdf]ESC manual[/link]

The Hedgehog

Are you going to try it today?!?!

snellemin

That was quick shipping man. Looks good. Now I have to wait for mine to arrive.
So did it come with the "dean" connectors installed?

Matthew007

It did come with gold deans, 12 gage hard wire all around, and it came with a male connector as you can see on the female one too, you can take it off and solder it to like a tamiya charger. So that's nice.

Yes, I tested it today on a partially a charged 7.2v 6c 3300mah generic radio shack battery.
You need to trim your radio to 0% throttle and wait 3 seconds (one time) before you plug and play or it wont release the throttle input to motor (read the esc manual 1st and last paragraph)..so that's a little annoying.
The esc uses the motor to give you error code beeps though so it's easy to figure out if anything is wrong.
Are all esc like this?

The motor has loads of torque; I tested it on a Traxxas Bandit with a 25T pinion and 74T spur (way over geared for most motors) for a few minutes. The esc did not get warm but the motor did. However, because of the heatsink is in the middle, it would fit but the pinion would not reach. The way I installed it was primitive.
You can't take the heatsink off, but the good thing about it is that it is not taped or solder to the can, it is part of the design oh the motor can.ergo the can is a heatsink like it says in the auction description.

I pushed the motor in until the heatsink touched the chassis gear box and installed one motor screw mount. It was on a few degree angle still for the pinion/spur to mesh. I only tried it at home and the cogging is very slight (fraction of a second) then everything is smooth (I had it programmed on soft throttle curve..i.e "max traction control" on say a dutrax steak esc) and was still able to spin tires on the floor it and it accelerates pretty fast.

Note though, the motor has a 1.5x longer shaft than a brushed mod motor which is not a problem but the shaft is not cut (no flat side). The pinion did slip slightly and left a small scratch on the shaft but it did work. This is something I can fix later. The grub screw was not really tight because I need a new allen wrench, however, my metric f-150 kit will have a large grub and allen head so it might fix the problem significantly until I can cut or sand the shaft some how to get 100% static friction between the pinion shaft and motor shaft.

On that note, I ordered the Tenergy 4500mah Propel pack and a MRC superbrain 960 i got off ebay slightly used for $35 including ship.

Once I break in the battery and get all my equipment (The Tamiya Hummer kit ,aluminum ta02 motor mount, modified aluminum ta02 main drive shaft (no boner, straight "lego" fit), 21&24T metric pinion (stock is 16&17T, 22 piece ball bearings, mrc charger, Tenergy Propel battery pack, 200A 75mV shunt to expand the 10A limit of my multimeter, and TIME) I will do a new post/mini review of the Hummer kit, this BL combo, and the Propel pack in three different posts because as you can see I like to leave specific details and blabber a lot.

snellemin

whooo, that was alot of blabber Good to hear that it works great. Well the motor is only 75% efficient and similar to some motor I saw on a airplane website for 30 something dollars. So the heat won't surprise me. I'll report my finding once I receive my set. I'm going to push the ESC with 6s1p and see how it behaves.

Just grind the shaft with a dremel or something. That is what is done to my 8s Feigao. I want see that hummer brushless built man.

Slo-V Flyer

Yeah use a small dremel sander tip adn grind out a flat-ish spot on the shaft. That's what I did to my Fiegao 7XL 5mm shaft. Hehe. Only need to have a light flat spot so the pinion can stick in it, and ever since it has not come off.

Oh and you'll be surprised the kind of gearing some motors CAN get away with in the Bandit. I gear my Novak 3.5R 25/78 and I'd be surprised if the temps got over 130'F in summer.... Yup, it'll pull wheelies with a lipo in there just like that, and still reach over 55 mph very easily with a 6-cell DTX 3800 (need a slight bit of runway of course).

Matthew007

k, cool

DaveThePainter

Esc [X(]

Matthew007

jessica alba[X(]

dirt101

LOL

snellemin

I'll post the nude pics of the ESC

d16z6

before I try one of these, do you think this setup would fit within the confinements of a 1:10 touring car? It's hard for me to judge the size of the ESC (planning where could I place that monstrosity) and if the design of the motor (can size) will fit where usually most motors are situated in belt drive setups.

DaveThePainter

lol

Matthew007

No you can't. And it's sold out on ebay.

Thank you come again.

pede_187

It's a pretty big esc

Matthew007

No, it works longer than 15 minutes grinch.

I tested it today with the esc programmed to limit the current (limits acceleration) so it don't chew anything.
After playing with it for 20 minutes the motor ran very warm but not hot, the esc was hot.
I was using proline 4.1" tires with a 21T pinion instead of a 17T.
I let it cool for 5 minutes to just make sure even though I set the esc to auto off if it got too hot. It seemed to cog pretty bad after the 20 minutes but that might be because of the heat, voltage drop and limited current setting??
After 25 min It was still going maybe 30mph at full throttle but I took it home to listen to The Savage Nation and follow up.
Right now the battery is at 7.28v shown by the MRC 960. At full charge the hummer was doing atleast 35 and it was uncontrollable because I need to stiffen the suspension for the bigger tires.
Thus I was at half throttle most of the time but it was still fast.

I'm getting my replacement camera tomorrow and I'll try to post a vid of it in play with both tire sets.
I have to do more testing and change, settings and hopefully my Tenergy Propel pack comes soon.

Overall it's really fun and impressive.
Here's a crappy vid of me spooling all four tires after the 20 min run.

[link=http://www.rcpics.net/img/87522]video[/link]