Brushless upgrade confussion

[alaskabliss]

Hey guys, Im new to this electric stuff and have a couple questions that I can't seem to figure out. This is what I have to upgrade:
TGY Aerodrive xp sk series 35-30 1100Kv 345w brushless
Grayson 30 amp brushless ESC

My first question is prop size. I think I need a 10x6. I want more thrust and im not a speed demon but do like fast lift offs.

Second Question is battery. Can I use the stock lipo battery untill I upgrade and what do I upgrade to?

Thanks for any help in advance cause im about to pull my hair out!

[alaskabliss]

Anyone willing to help out a poor confused chap???

[belem]

Suggested prop on that is a 10x5. Stock battery is 15C right? Might get warm or puff if you push it too hard. Might want to pick up some 25-30C batts if you're gonna push it.

[ginginho]

To save your batteries/ESC/motor* from getting damaged, it well worth getting yourself a wattmeter to know exactly what is going on when trying different props. It pays for itself in next to no time.

* - Select as appropriate.

[Dillzio]

I'm with Ging, you really need a wattmeter to be sure. As well as prop size, the brand/make, shape, weight all have a significant effect too. Generally though, for a 300w+ 1100kv motor a 9x5 or 9x6 should give you tonnes of power.

[flydiver]

345W motor?

Read this first:
Re: Dillzio-- Brushless setup question?
« Reply #11 on Jul 19, 2010, 11:39pm »
supercubclub.proboards.com/index.cgi?action=display&board=tt&thread=3218&page=1#22332

Stock lipo will not last long at all, you'll toast it.
The Cub is a pretty balanced system. You change much, you probably have to change everything.

Plus a 30A ESC is borderline (or worse) if you are going to try to use that power. NO, you cannot safely use throttle limits to use it.

345W/11v = 31A

[alaskabliss]

Well I guess I need a watt meter...

My math is as follows:

345 watt motor minus 10% hype of what it really is equals 310.5
That should be 28 amps

I guess the watt meter will give me exact numbers. Can you buy one at any electronics store or is it something I need to order?

[flydiver]

You need to order. Lots of shops carry them- about $50
You can also do this - it works but is not quite as versatile or useful:
www.rcgroups.com/forums/showthread.php?t=949923

Did you read the post about figuring out the battery? That was important also. You are way over the stock battery ability.

[Dillzio]

I got this wattmeter from hobbyking and i'm pretty happy with it. It's about the cheapest one available: www.hobbycity.com/hobbycity/store/uh_viewItem.asp?idProduct=10080

Remember to get some battery connectors for it too.

[Dillzio]

Aug 1, 2010 16:33:53 GMT 1 alaskabliss said:

I need to get a watt meter but I really don't wanna wait for it to get here!!! I ordered my motor and servos almost two weeks ago and it still hasn't showed up. everything was in stock and it has showed shipped for over a week now!!!

Heres a question. im confussed about amp draw. The bigger the prop the more amp draw? example: 10x6 will draw more power than a 9x6 therfore less flying time and possibly need bigger ESC? I have the TGY 35-30 sk with a 30amp ESC. It looks like you have the same set up. Also depending on what battery I use it will change the amp draw? Im using the stock for now till I can convince the wife to let me spend more money. I am not a WOT kinda guy. I love flying the SC they way it's big brother does, slow. I would think I would be good as long as I don't run WOT more than to take off... what do you think?

Also, is this motor set up pretty bad *ss compared to the stock SC LP or just a little bit better?

Thanks

Your order is coming from across the other side of the world with budget shipping, I'd give it at least three weeks. It takes mine about two weeks to get to Australia, but only about a week if I pay for express. If i'm ordering a kilo of stuff it's only an extra 2 bucks for express, so buying in bulk is the way to go.

Yes, the bigger the prop, the more the amp draw, and the more thrust it puts out. With all other things being equal, a 9x5 draws more power than a 9x6, and a 9x6 draws less power than a 10x6. A well chosen ESC will be overrated, so you shouldn't really need a bigger ESC to run bigger props, you should really be using that bigger ESC anyway. If you use an ESC that's barely rated high enough to do what you want it do, you'll be putting a lot of strain on it, and it will get very hot and suffer wear and tear. If you happen to accidentally fire your motor up while your plane is laying on it's back and the prop can't spin (like I did in the video of 'my new cub') you could potentially blow your ESC unless you have a bit of a safety margin.

Changing your battery CAN change your amp draw, but again, if you're using using a sufficiently overrated battery that should not be an issue. Using an underrated battery will cause the battery to get hot, and reduce it's overall lifespan. An underrated battery can also potentially puff up, explode or catch fire. The stock battery is rated to 15C, and as it's a 1300mah battery, it can provide a maximum of (15Cx1.3amps=) 19.5 amps. If you want to draw 30amps through that stock battery I would stand well back! If your wife doesn't want you to spend more money on your batteries, you can rationalise the expense as 'safety'. There are plenty of pics online of damage done by lipos that have burst into flames so that should strengthen your case.
These batteries are good for super cub brushless conversions:
www.hobbycity.com/hobbycity/store/uh_viewItem.asp?idProduct=8932
www.hobbycity.com/hobbycity/store/uh_viewItem.asp?idProduct=6306

Is this motor set up pretty bad *ss compared to the stock SC LP or just a little bit better? Well, it's sort of like taking the 1.8litre 4-cylinder enging out of a toyota corolla and replacing it with a V8. Many people would argue that its TOO powerful. Generally speaking, this motor is about the most powerful you'd want for a cub: www.hobbycity.com/hobbycity/store/uh_viewItem.asp?idProduct=3886 (ignore that it says it's 400w, that's BS) . The motor I have is the 35-30, not the SK version, and many would argue that mine has as much power as you'd ever want for a cub.
You have the SK series of the same motor, which is about 50% more powerful again.

A super cub with that 35-30 SK motor should REALLY scoot. Just beware using it with your 30a ESC, as without a wattmeter you can't predict if you're going to go over the 30a mark. I think you should be able to use a Master Airscrew 9x5 without any problems.

[alaskabliss]

Thanks Dillzio, that was alot of good info. So I need some batteries and a watt meter... I guess I need to take the honey out to dinner and sweet talk here ;D
I will hit the LHS when I get in and look for the 9x5 prop to be safe till I get my hands on a watt meter. Do the LHS have a store wattmeter that they may let you bring your plane in and test??? it would be good for them since your gonna buy what you need while your their

[Dillzio]

Aug 2, 2010 16:52:05 GMT 1 alaskabliss said:

Thanks Dillzio, that was alot of good info. So I need some batteries and a watt meter... I guess I need to take the honey out to dinner and sweet talk here ;D
I will hit the LHS when I get in and look for the 9x5 prop to be safe till I get my hands on a watt meter. Do the LHS have a store wattmeter that they may let you bring your plane in and test??? it would be good for them since your gonna buy what you need while your their

I doubt they have a store wattmeter you can use, my LHS doesn't even have some Z-bend plyers! If they did have a wattmeter however, I doubt they would have the appropriate connectors for your battery.

I guess I'm a bit of a pessimist.