# Need advice on powering my stage prop.



## TeamTEOR (Oct 6, 2008)

Ok, I am have built a stage prop from Star Wars, we all know it well. Since the last brushed motor I had & used burned up (not taking my Super Rooster with it thankfully) along with my new 6 cell NiMh battery, I figured that I would try a brushless solution. Having good luck in the past with Novak I gave them a call. They had suggested to power this prop with a Havoc 21.5 motor and a 2s2p lipo and I would be able to run it all day long with no heat issues, and no power issues. They also directed me to use the smallest pinion that I could find. The chassis used for the project is a Bolink Legends Chassis with the stock 81 tooth spur. Taking Novak's advice I ordered up a Robinson Racing 48P Pinion Gear that was set with 12 teeth. 

The motor is nice and smooth (very happy as it is what I had hoped for), but things seem to me a little off with the power. There is more power in reverse than in forward, and the brakes are almost non existent. I am figuring the Novak ESC is in need a little reprograming as well, but the docs do not seem to be clear on how to do it. 

In running the old brushed setup it ran ok, but I knew the motor was tired, it was not rebuildable and had seen better days. It was quite snappy (during the first 2-3 runs), and made the prop look the same as it did in the movies. I am just hoping to achieve the same level of performance with the brushless, and also with the gained efficiency have longer run times when out at public showings. 

At the moment I am waiting on payday to order a new Lipo pack, My thoughts were buying a 2s 4400mAh 10C Li-Poly Pack from Common Sense RC for $99, but I am open for other ideas. 

So I need to reprogram the ESC first, and then maybe fudge with the gearing. Thanks in advance for any and all help.
Tom

Here is a picture of my little black prop.


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## hankster (Jan 1, 1998)

Yes, I would reprogram the ESC first as you may not be getting full forward (by the sounds of your description). Once you reprogram it you can see if you get enough speed and adjust gearing from there. There are many other packs that are far less expensive then $99. If you don't mind waiting 10 to 12 days for shipping, you can get some good deals from rcMart (one of our Sponsors). They have Yeah Racing packs... http://www.rcmart.com/catalog/battery-charger-batterylipo-c-52_973.html

Yeah 4000mAh 25C - $60
Yeah 5000mAh 25C - $70
Intellect 4600mAh 20C - $50


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## TeamTEOR (Oct 6, 2008)

I have no issues dealing with RC Mart, they have served me well in the past. Thanks for that idea. I'll go after their 4600 pack at that great price.


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## TeamTEOR (Oct 6, 2008)

Ok, got things a bit more settled. Called Spektrum (the radio is a DX7) and waited a long time on the phone, but got them. Apparently this guy came across something like this the other day with a person who called in about a robot setup. They had me reverse the ESC and the radio and I've got plenty of power now. I turned up the brakes in the ESC to a frequency of 8khz (max setting) and also to 25% (also max setting). Also, the throttle curve in the ESC was set to Expo, and that was another issue, so it got set to linear. Now it runs much better, and more of what I had expected it to be like. 

The funny thing now is I am going to need to make a wheelie bar or regear again. If I go in reverse there is no brake so when I go forward I just lifts the front end into a wheelie. I assume if I go up a 16 tooth pinion that it will tame that. The final drive ratio would change now from the 6.75 down to 5.0625, or would maybe a 18 tooth be better dropping down to a 4.5 ratio. 

I am not going for speed with this setup. I am happy with 5 mph or so, as long as it is efficient and has a long run time.


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## hankster (Jan 1, 1998)

I think what I would suggest is a 1S pack. It will have half the voltage and should help cure the "wheelie" problem, the speed problem and even increase run time. Not sure if rcMart has any, SMC makes some for racing applications so they are a bit expensive (about $65).


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## Porksalot4L (Nov 4, 2002)

hank the only issue with 1 cell is then there would need to be a booster or a reciever pack. just might be one more thing to do during the day?


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## hankster (Jan 1, 1998)

If a booster is needed, then nothing else needs to be done other then hook it up one time. I thought that Novak ESCs normally work fine with the single cell packs?


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## TeamTEOR (Oct 6, 2008)

I was not aware that the Novak system could handle the low voltages of a 1s LiPo like that. I know it can handle 4 cell NiMh, which is still close. It does have that big capacitor in place, guessing that is what would be called a booster. 

I will pass by the hobby shop and pick up a couple of Deans pigtails. I do have a 1s battery I can attach as a test. Actually it is a 2s pack that I took apart to power LEDs. I think they are 10c 1200mAh. Giving it 1 min or so of run time in the house won't kill it (bad, lol) so it should be interesting to try it. I'll make them into a 1s2p so I don't kill them. 

I found this calc and it had some interesting things to say about run time and speed. I'll take its info as an approximation.


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## hankster (Jan 1, 1998)

If it doesn't work in 1 cell, Novak makes a voltage booster that can be used to increase the voltage for the receiver and servos.


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## tgardner41 (Mar 15, 2007)

TeamTEOR said:


> ... The funny thing now is I am going to need to make a wheelie bar or regear again. If I go in reverse there is no brake so when I go forward I just lifts the front end into a wheelie. I assume if I go up a 16 tooth pinion that it will tame that. The final drive ratio would change now from the 6.75 down to 5.0625, or would maybe a 18 tooth be better dropping down to a 4.5 ratio.
> 
> I am not going for speed with this setup. I am happy with 5 mph or so, as long as it is efficient and has a long run time.


Nice looking machine, I always envisioned 'em crapping little AAA batteries all over the death star! 

No need for a wheelie bar. To cure wheelies in our Outlaw Legend class (10.5 six-cell), we just added lead weights to the front axle plate until the front end stayed planted the ground coming out of the turns. Perhaps you could do the same.
:dude:


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## TeamTEOR (Oct 6, 2008)

Yes, I'll be moving things like the internal speakers and stuff forward to help. So many projects so little time, lol.


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## TeamTEOR (Oct 6, 2008)

Well, the 2p LiPo (8c, 4000mAh) didn't work out to well, seems that alone the current draw made it hit the LVC quick.

So it is back to 2s, and I'll be relocating stuff up front.


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## TeamTEOR (Oct 6, 2008)

I put on my 6 cell NiMh pack, and then installed the 18t gear. At walking pace it will draw about .5-.7 amps as per my watts-up meter. Also it will no longer wheelie, which is a good thing for safety. I am still not happy with the brake, but now I need to program the ESC to realize what the throws are on the radio if it is possible. As per the calculators (Dark Horse), it is possible to get 220-240 mins of walking pace play now on a 2s4000 pack. Perfect.


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