vik

My Feedback: (1)

Hi All,

I´m considering power plant for next project (2m Spitfire or Mustang).
I have seen some Axi and Eflite setups with about 10s packs 5-6000Ah
What I´m wondering about is if someone have reductor?

The theory is nice and it shall be possible to use smaller setup and run large prop.
The question is if this is good idea and if the speed will be ok?
Does any one make such reductors?

For field equipment: do you use car battery or have some external power source?

Thx

REDUCTOR - GEARBOX

MaxAdventure

My Feedback: (7)

I use large direct-drive low KV outrunners on 8S-12S setups swinging 18inch to 24" props, the low KV outrunners have plenty of torque and I'm hitting 2.5KW to 3.5KW. Mostly I'm cheap and go with Turnigy motors, bad QC, but they work for me

CorsairJock

My Feedback: (90)

Actually, I think you mean "reduction", as in gearbox reduction.

A few years ago, reduction gearboxes were the only practical way to obtain reduced RPMs/ higher torque from electric motors which would allow us to use the bigger (but slower turning) props that you seem to be looking for.

That was then, this is now. Modern day brushless ourunner motors come in a variety of windings, which if properly chosen: allow the user to obtain the same end results as using a gearbox on a higher RPM motor.

A few years ago, I used gearboxes on just about every electric plane that I had. Now, since they are un-necessary, and they make more noise AND require more maintenance: I use appropriate low KV outrunners instead. Example: while most prefer the AXI 4130/16 over the ( lower KV) 4130/20: I use the 4130/20 and swing a 17 x 10 prop on my Top Flite Mustang. Outstanding climbing ability, very good efficiency (only draws 32 amps static on 6S), and still capable of 80 mph or so passes.

Yeah, what he said: "low KV outrunners".
Why install a gearbox if you don't need to?

vik

My Feedback: (1)

The point was to use smaller motor and smaller battery and get same result as with direct drive.
I know the direct drive is possible.

MaxAdventure

My Feedback: (7)

Well, you will have a friction loss on the drive train, you have additional rotating mass as well as additional dead weight - this all will absorb your watts into the system with a lower watt percent available for spinning the prop so you will end up with bigger batteries. The suggestions are provide the most efficient and simple way to power a large electric. The one place I still see smaller higher KV motors useful is using geared in-runners when you have a very tight mounting area like some smaller turbo prop scale applications or a performance sailplane.

it's really quite surprising how small (weight and volume) a good out-runner is compared to the equivalent petrol IC engine.


as for not addressing your power source for battery charging:

I mostly keep enough sets of packs that I don't need to charge on a day I fly. I charge at home starting a few days before a planned flying day using a very large power supply on my CellPro10 supplemented by a few other chargers for smaller and Nickle based packs. My primary club field has installed a solar collector and Pb/Acid storage and we often charge packs at the field from that. I do know some fields have A/C power available and I've often seen personal petrol generators in use at events. I personally used to charge smaller packs (3S 2000mAh) off my car battery however between fear of running the car battery low and damaging it (not a deep cycle) and fear of LiPo thermal-runaway fires (most of my packs have experienced some bumps and bruises - never had a charging fire yet) I have stopped that practice.

Ron101

My Feedback: (22)

I'm with Maxadventure,

I have a 1521 Neu motor with a P-42 gear box on a 30% extra 260
I spin a 24x12 prop with 12s 5000 mah at 4500 watts... it has much more power than a DA-50 and would turn a four blade with no problem

It's been a great setup and has a cool sound

I'm building a top flight GS P-51 right now but want some good speed so I went with a little higher KV AVI 5345/14 with a 21x14 prop... hope to have it in the air in the next month

check out there thread:

http://www.rcuniverse.com/forum/m_22...%2CP-51/tm.htm

about half way through you will see Lax Life used a large Neu inrunner with a four blade and got some serious power!

hope that helps some

vik

My Feedback: (1)

Hi Ron
Yes I have seen your Mustang. It will be great to see some video from the test flight.
Can you give me some additional info to your Extra?

Honestly I thing the direct drive shall be the best, but I was really interested if there is some other way as well.

Ron101

My Feedback: (22)

I have a dietrich extra 260 it 50 cc sized
I have the Neu Motor 1521 1.5y with a P-42 neu gear box, I turn a 24x12 APC prop with a castle crations 110HV but I'd go with the CC 160 ESC now
the plane is for 3D and only 17 1/4 pound... I have flown with my friend that has the same plane with a DA 50 and I have much more vertical than him
I get about 6:00 to 7:00 flights depending how I fly it...

If my axi doesn't fly my mustang well and if I can get the pack forward enough I will put a neu motor setup in it
but I'll have to see how it goes...

I'll be sure to get video

1UGLYPUG

HI,,, I am building the Top flite Giant Scale Corsair,,, I would be very interested in how your set up went with the mustang! I have been looking at a Hobby King motor,,, 80-100A-180 KV supposed to be 60cc to 80 cc equivalent ,,, around 100 bucks,,, But, would like to know what motor( and size it equates to),, and the cost of the motor you are using,,, With all the work, I really don't know about using the cheap stuff, if I can afford the good one I am sure you are using,,, and would be interested how it is working out for you,,, If it would not be a lot of trouble, please let me know,, Hope yours is working out very well.