The Voracity tuning thread

[killerbob]

Hi guys, Thx! Regarding the math on the watts, there is something i dont understand: where does the power of the motor and the kV come in to play? Sure they influence watt output as well? Or is this about motor heat?
I already reinforced my hull with cf :). Speed is dangerous but FUN

Is this also in your opinion the best prop? And what would be the best (still safe) prop for stock setup?

No ... Power = Voltage times used Ampere P=U*I - part of the laws of good old Mr. Ohm ... Mr. Resistance...

KV is how fast you motor will run in RPM pr. 1 Volt ... So a motor with a kv of 1000 will run 1000 rpm if you supply it with 1 Volt ..... at 10 volt it will run 10.000 - at 20v 20.000 UNLOADED ...

So what you want to do is to decide how fast your prop should spin... knowing that you will loose quite a bit when you load the motor...

In my example my motor is 1730 kv... fresh charge is 6s is 4.2v x 6 = 25.2 v... so in theory - provided that there is NO LOAD and NO LOAD on the batteries and they are able to hold 25.2V my motor will spin 43.596 rpm (25.2 * 1730) ... in reality a LOADED 6S package in good temp and health is 21.0 - that is 21 * 1730 = 36.330 RPM ... In reality there is also load on the motor and I am seeing 33.2xx on my telemetry in water at full speed - but again that is with lipos suffering from low temps - so I have 19.6v - in theory 19.6 * 1730 = 33.908 ...

KV has NOTHING to do with power - just RPM

With 6S I would keep in the range 1500-1800kv in the Voracity ... And I would go for a motor capable of around 3000w ... The 4092 is 2600w continuous and 4200 peak ... How long time peak is peak I don't know, but so far my motor is not more than hand-warm after a good beating

[Keagan-Z06]

Run your trim tabs level with the bottom of the hull or just a tiny tick down. Watch this video to see what I'm talking about: https://www.youtube.com/watch?v=zKKTryJdASw . For the strut adjustment check out post 289 in this same thread: http://forums.offshoreelectrics.com/...716#post647716

Thanks a lot, I assume adjusting trim tabs is a matter of bending the tabs or do i have to remove the allen keys to adjust height? Also I am having bit of a problem, maybe you can help or Rafael. My second run was today, and each run I have died mid water, Its not the batteries I think because I initially thought it was that and came home to charge it and it took about half the time to gain full charge. I had a beeping noise and a green light flashing every second or so from the ESC. I put in the freshly charged batteries and it did the same. The boat ingested a good amount of water the first time but after some extra grease on the second run it wasnt so bad. I found out that the Transmitter receiver was wet and each time I had to tear it down and use can air to dry it out and Bind over. Since then I have relocated the Receiver to the underside of the boat just next to where the antenna inlet is. I sticked it with Velcro and will try again to see if that solves my problem. Anyone had this happened to them?

[Voracity]

Hi guys, just went to the lake for first run after rebuilding the boat (i strengtened it with carbon). Few things I noticed: the motor sounds 'metallic', scrapy ( I am not sure how to explain correct in English), especially noticable on lower rpm. It is not the shaft (I tried without and sound was the same). The shaft at the motor can be moved a little and there is a clicky sound to be heard when doing this. Any thoughts? I had the motor out but it can only come back one way, so position has nothing to do with it i recon.

Second thing is there comes a lot of (brown) grease from the strut, maybe I had to seal this when putting back together? Can it be the shaft is not lubricated enough since it comes out so fast?

The boat was not fast (39 mph on 6s) but the water was glass, so this may be the reason. I had 52 mph passes before

Thanx again!

[Voracity]

@Bob/Arrover you mentiones your water jackets were different sizes. Which exactly?

[martin]

If its nothing to do with the drive assembly then I sounds like it could be motor bearings.

[arrover]

I was going to say motor bearings too. I can't remember, did you ever sink or flood your Voracity?

My water jacket is a 68mm: http://forums.offshoreelectrics.com/...870#post644870

[Voracity]

Ai if it are bearings is this big problem? Can it stop suddenly?

Yes it floodes twice

[arrover]

It sounds like your bearings might have rusted. If your boat sinks you need to remove the water from the bearings quickly so they don't rust. I am not an expert in this area but I think you will need to replace the bearings or replace the whole motor. These motors spin at 30,000 - 40,000 RPM so the bearings need to be smooth.

[killerbob]

Agree. I had mine flooded and then it sat on the shelf for 2 weeks. Both bearings rusted to the point where I had a hard time turning the prop by hand. Worse - the anchor inside the motor was also rusty. This is the reason I now run the leopard 4092-1730kv. I was happy with the stock motor but actually found that it was cheaper to buy a leopard than to order a new stock motor from horizon.... The stock motor is now rebuilt with new bearings. Costed like 10 bucks for 2 new bearings. The front one is easy to get out - the rear one a lot harder. But it is done. It will be kept in the drawer for future use... Maybe in something else...

Learned the lesson. Now I use a thin spray oil on all my motors after each day of boating and have not have a problem since. The internals of brushless motors is not harmed by the stuff. Note WD40 is NOT the stuff. It removes the moist but do not lubricate. For now I use Tri-flow. It is a can I have had for years, don't know if I can get more when the can is empty, but it should not be hard to find a replacement

[martin]

Re future motor maintenance, most light oils is better than nothing. However Scorpion motors do a specific oil for motor bearings, its cheap & comes in a bottle with a thin spout to get into tight areas. If you cant find a Scorpion dealer then Hobbyking sells Scorpion oil for around $6.

[Banzee]

Hi guys, just went to the lake for first run after rebuilding the boat (i strengtened it with carbon). Few things I noticed: the motor sounds 'metallic', scrapy ( I am not sure how to explain correct in English), especially noticable on lower rpm. It is not the shaft (I tried without and sound was the same). The shaft at the motor can be moved a little and there is a clicky sound to be heard when doing this. Any thoughts? I had the motor out but it can only come back one way, so position has nothing to do with it i recon.

Second thing is there comes a lot of (brown) grease from the strut, maybe I had to seal this when putting back together? Can it be the shaft is not lubricated enough since it comes out so fast?

The boat was not fast (39 mph on 6s) but the water was glass, so this may be the reason. I had 52 mph passes before

Thanx again!

WHat is the glue you used for the carbon ??

[Rafael_Lopez]

Some of us come to learn the hard way that although brushesless motors are "maintenance free", the bearings that support the rotor are not. It's happend to me before. I've forget to spray them with WD40 after my motor gets wet and the bearings seize up. This is both in my boats and in my RC cars.

We use ABEC 5 bearings in all of our motors, which is a mid grade bearing, but they are chromed ball bearings. So if you don't maintain them and they get wet, they will rust. Of course you can always replace them with stainless steel or ceramic bearings for peace of mind, or in case you're as forgetful as I am.

I make sure a small spray can of WD40 and a needle tip bearing oiler are in my pit box, every time I go out.

[paulfromtulsa]

Some of us come to learn the hard way that although brushesless motors are "maintenance free", the bearings that support the rotor are not. It's happend to me before. I've forget to spray them with WD40 after my motor gets wet and the bearings seize up. This is both in my boats and in my RC cars.

We use ABEC 5 bearings in all of our motors, which is a mid grade bearing, but they are chromed ball bearings. So if you don't maintain them and they get wet, they will rust. Of course you can always replace them with stainless steel or ceramic bearings for peace of mind, or in case you're as forgetful as I am.

I make sure a small spray can of WD40 and a needle tip bearing oiler are in my pit box, every time I go out.

Could you post a video on how to oil the bearings without opening the motor

[Rafael_Lopez]

You cant oil the inner bearing without opening the motor. The rear bearing doesn't have to be serviced as frequent as the front though, for a couple reasons. 1-It is better protected from the elements, as long as you don't submerge your motor. 2-The rear bearing doesn't carry any load, like the front one does. What I mean by that is, when the cable is under load, it tends to shrink. This pulls the rotor forward and puts an extra load on the front bearing. This causes the rear bearing to only spin, with no load on it, unlike the front bearing.

If you do intent to lube the rear bearing, the easiest way to do so is to remove the front end bell by removing the retainer screws that hold the end bell in to the can. You then pull out the rotor and use a needle tip oiler to reach as far as you can in to the can and put a drop or two of oil on the bearing. The other option is to remove both front and rear end bell screws, pull out the rotor and use a piece of wood dowel no greater than 15mm in diameter and a hammer to pop out the rear end bell.

They use loctite to on the screws that hold in the end bell in place. When the end bell has never been removed before, I use heat from a soldering iron on each screw to break the loctice bond and ensure that I don't strip out a screw head. Some loctite also spills over to the end bell so heating it also helps break the bond between the end bell and the can.

[killerbob]

HOLY SMOKES ... Read on

As you may already know - I am a big fan of Telemetry - And as you also may know I have copied arrowers setup for the Voracity ... Leopard 4092 1730kv, 6s, Turnigy 180A esc, ABC 2214-10-50 and OSE heavy duty flex.

But with this "new" setup - I started to get some problems.. First - I found it odd that I would get 21.0V under load with the stock motor and X452 at a current of 144-146A - but with the new motor the current was 148A but voltage dropped to 19.6V - that was actually a drop in wattage... But I wrote it off blaming the cold weather (36F)

Next the boat started to stop in the water with plenty of capacity left in the packs. The ESC was rather hot - not alarming - but just above comfort-zone holding it.

In my post her #407 I reported 148A with the x452 and the new motor - then I switched to the ABC 2214-10-50 .... Saw an increase in speed and "willingness" to fly, but still 148A under load

Started to investigate the cut offs.... First I suspected the UnisensE Telemetry sensor .. it is rated 100A continuous - 120 for 20secs...And I pulled 148A for maybe 5 secs

Asked SM Modellbau if the sensor was able to cut off current if overloaded - and told them about my problems. They got back to me and told me that the sensor would pass on current until meltdown, BUT that 148A was the end of the line for the measuring range. So even if I pulled 200A - it would still report 148A.... Worse -that would also affect the "used capacity" reading

I ordered the UnisensE 280A version right away

Yesterday at the pond ... 5800 mAh Zippy Compact 60C packs on board - 280A UnisensE sensor installed .... full speed .... 235 A !!!!!!

So now I know why the boat stopped - simply hitting voltage cut-off ... And now I know why the 180A ESC is rather hot ... And now I know why my 40C 5000 mAh Zippy packs feels old and tired compared to my recent Turnigy Graphene 5000 mAh packs rated 65C (40C @ 5000 mAh - is 200A - 65C is 325A )

Didn't get at chance to try the Graphene packs yesterday - but the Zippy Compact 5800 mAh 60C held 20.2V under 235 A load - that is 4.747 W !!!!!!!

Arrower - we are playing with fire here :-)