[Flyforfun2]

Hey Guys:

Just built a Alph 450 Sport ARR with E-Flight 480 1020KW motor..I was looking for more power but I am surprised it is not more!

I used a nylon 10X7 propellor.....Any ideas what to try next?

Flysforfun2

[AAM Flyer]

That motor is designed for up to a 10x7 to 12x6 and I almost always add an inch at altitude.... I would say try an 11x7 first, watch your amps....but also look at a E Prop vs an Slowfly... I like the APC E props....

[daniel]

I've found two props that work well here with the Park 480 - the 11x7 works nicely if you want good speed and don't want to use the burst range of the motor. If you want good thrust you can use the 12x6, but you must be careful not to run at full throttle for more than 10-15 seconds, and allow a cooling period between bursts. Use the APC Thin Electric, NOT the Slo-fly. The Slo-fly props will over-amp the motor.

The above applies only if you use a 3-cell Lipo - any other voltage will result in different numbers. Use the good battery too - the 12x6 can make it pull about 30 amps. Need good ESC also - I use the Thunderbird 36.

[daniel]

Oh BTW, it's "kV" (small k, big V) - meaning the voltage constant of the motor. KW means kilowatts, and the 480 is only a 0.275 kilowatt motor

[Flyforfun2]

Thanks.......... I am lucky to spell it right much less with proper capitalization......... Will try larger prop......

"Necessity is the Mother of Learning"

[nashopel]

Kilovolts (kV), 1,000 volts
The rating (Kv) of RPMs per volt as used in reference to the rotational speed of brushless motors

[daniel]

Oh yup, yer right... Kv is the voltage constant. I got it backwards

http://en.wikipedia...._electric_motor

[Steve Eiche]

Flyforfun2, on 28 January 2010 - 01:52 PM, said:

Hey Guys:

Just built a Alph 450 Sport ARR with E-Flight 480 1020KW motor..I was looking for more power but I am surprised it is not more!

I used a nylon 10X7 propellor.....Any ideas what to try next?

Flysforfun2

The the 10x7 prop recommended would likely work well at low altitude, but with electrics here at altitude you will want to go up an inch in diameter to compensate. Note this is the opposite of what you would do with a nitro or gas motor. An 11x7 APC Thin Electric prop will give you good performance and speed with that motor, while keeping the current to a safe level. A 12x6 APC Thin Electric prop also works well with that motor, and will give more thrust at low speed, but a slower top speed. If I were you, I would probably try them both and see which you prefer, assuming the current draw with each stays in the allowable range for the ESC that you are using. My guess is that you would like the 12x6 at first, as the low end thrust will get the plane in the air quickly, and will be a little easier to manage. The 11x7 will fly it faster, which you may like as you get used to the plane. Don't use Slow Fly props for the motor, as that motor will spin them faster than APCs recommended safety limit., as well as drawing more current as Daniel mentioned.

I would highly recommend using a wattmeter to make sure that you are keeping the current draw in the recommended range for the ESC that you are using. A wattmeter is a critical piece of equipment if you are flying electrics. They don't cost much, and can save your equipment. Lots of motors and ESCs get smoked because people don't test the power systems to make sure that the are keeping the power to safe levels for the equipment. That motor can handle more than 300W for short periods of time (BTDT), but the ESC may not. If you are using a high C rating (25C or more discharge rate) battery, you may be getting close to the current ratings of the ESC on the recommended 25Amp ESC. Personally, for that motor I would use a 30+ Amp ESC to be safe, like the Castle Creations Thunderbird 36 that Daniel recommended. In fact, that is exactly what I use in the plane I have that has the EFlite 480 1020 and APC 12x6.

All the ratings, etc. for electrics can be a bit intimidating at first, but once you get a few thing figured out it is pretty easy.

[JoeSantora]

I'm a fan of increasing pitch instead of dia. at altitude. Try this http://www.rcgroups....ad.php?t=213592

[Steve Eiche]

Maybe it is just how I fly, but I seem to prefer the "feel" of larger diameter, to increased pitch. I don't think APC makes a 10x8. The next size up pitchwise that they make would be 10x10, which, IMO, would suck (highly technical term) in a trainer, and likely draw too much current for the motor. The next choice would be 11x5.5, but I think that would be too slow and power with that motor would be limited. The 11x8 draws too much and is slow getting off of the runway.

From my experience with that motor on 3S, 11x7 and 12x6 are the sweet spot here. The current draw maxs out the motor, and the performance is very good at all speeds. For a bank and yank sport plane, the 11x7 is fast, yet will still get off the runway fairly quickly. The 12x6 is the choice for slower planes, as well as for precision and 3D.

Props are cheap, try them all and see what you like. As long as the current draw isn't too high, any of them will work.

[Franny]

Hi Flysforfun2,

Do you have a Watt meter? As Steve mentioned, you can get a hole bunch of info on your setup and you can protect against driving beyond the specifications of each of the components. Coupled with an RPM meter, you have pretty much all the data you need. You might want to look at the voltage drop as you get towards the max wattage. That will tell you if you battery is up to snuff. So, in a nut shell, the voltage sets the RPM and the motor will draw whatever current it needs to maintain that voltage under load. After that perfect world, the voltage will begin to drop. RPM sets your tip speed and regulates your max forward flight. Also, the larger and slower the prop, the more efficient it is generally. So, big slow airplane, big slow torquey prop. Fast airplane, fast, small prop. You can use pitch to adjust the current draw if you like your tip speed (RPM). One additional factor is how the prop will change with forward speed (air flow) as it "unfolds". The higher the pitch, the greater the difference between a static bench run and how it performs in the air (they stall or cavitate to some amount on the bench).

I hope that helps...

Franny

[lt crunch]

JoeSantora, on 31 January 2010 - 10:29 AM, said:

I'm a fan of increasing pitch instead of dia. at altitude. Try this http://www.rcgroups....ad.php?t=213592

This is theoretical knowledge versus practical one would assume Joe? I haven't seen you actually slice air with a propeller since...oh, I can't remember...was Elvis still alive?
Were Brontosauruses still walking the pre-cambrian shoreline at Rooney Road???

Time to fly!!!

Frank D

[daniel]

lt crunch, on 01 February 2010 - 02:37 PM, said:

This is theoretical knowledge versus practical one would assume Joe? I haven't seen you actually slice air with a propeller since...oh, I can't remember...was Elvis still alive?
Were Brontosauruses still walking the pre-cambrian shoreline at Rooney Road???

Time to fly!!!

Frank D

What I posted is actual experience. I've used the 480 on two planes, one of which I flew for two years until I busted the elevator. Steve likes 3D, and for that purpose the 12x6 is probably better... if you use the 11x7 it really makes a big difference - you have to fly smooth and keep the speed up because you can't punch out real fast if it slows down. If your plane is light enough for 3D, then the 12x6 is fine, but if it's a smooth flying plane, then you'll want to use the 11x7.

As Franny mentioned, it's still a good idea to do a power test. I've got two 450s here that use different amounts of power with the same prop... so don't just take my word for it, understand what you're doing and make a data-driven decision. Measurements will also help you figure out how to fly the setup - you'll be able to approximate your flight time, and you'll know whether full throttle puts you in the burst power range or not - this will affect how you fly. On my little Funtana, I can't use full throttle for very long, because that one flies better with the 12x6... but on the Brio 10 (same size plane, little heavier) - I used the 11x7 and could buzz around on full throttle for the whole flight, not that there's any reason to do that.

On the issue of taking manufacturers recommendations and going up an inch from there - it's a little more complicated than that. What I have found is that the bigger the propeller, the more difference it makes when you go up in altitude. So for example, an 11x7 will pull significantly less power here than at sea level, but the 5x5 I run on the little pink plane - it pulls exactly what it's supposed to at sea level. So again, you really need to measure what you're doing - get a watt meter and check what you're getting. Find one of us at a meeting or at the field, and maybe we can help you figure it out.

There is a motor calculator on this web page, but it doesn't let you change the density altitude, and it doesn't have the Park 480 motor. It only gives you a ball-park number too... most of the time, my measurements come up pretty different from what this calculator says, except in the case of small props running at high speeds.

http://www.brantuas....ezcalc/dma1.asp

[JoeSantora]

lt crunch, on 01 February 2010 - 02:37 PM, said:

Were Brontosauruses still walking the pre-cambrian shoreline at Rooney Road???

Time to fly!!!

Frank D

[Flyforfun2]

ALRIGHTY THEN!!!!!!!!!


Guess I will try a couple of props with volt meters and get back to you guys............ Thanks for the help! One of the best things about joining this club is I can always find someone that has been there before........ Even if it was a LONG TIME AGO!!!!!!!


FLYSFORFUN2

[daniel]

Flyforfun2, on 05 February 2010 - 12:20 PM, said:

ALRIGHTY THEN!!!!!!!!!


Guess I will try a couple of props with volt meters and get back to you guys............ Thanks for the help! One of the best things about joining this club is I can always find someone that has been there before........ Even if it was a LONG TIME AGO!!!!!!!


FLYSFORFUN2

You need a pass-through watt meter so you can read the actual wattage being pulled from the battery. A radio shack multi-meter won't really do the job... see video.

http://www.youtube.c...h?v=ieNBppbgCvM