Is a similar size motor with much higher KV alright?

[Crunchybananas]

So A very nice guy gave me a elitemodels 8mm epp acrocub kit, but it is just the foam. it recommends a 2206 -1900kv motor with a 8x4.5 prop but I thought maybe I could just get a flitetest powerpack and not buy things separately. The powerpack F has a 2205 2300kV motor with a 6x3 prop, and I am not sure if that is ok for this plane. I thought maybe because the motor is similar size. if this is not the correct motor, should I buy everything separately or is there another pack I can buy? thank you!

 

[JasonK]

that F pack motor is slightly smaller and higher kv, so it probably can't run the same size prop at the same number of cells. How many cells does your kit ask for?

 

[Hondo76251]

One of the more significant learning curves in this hobby is understanding the numbers as they relate to motors, batteries, and potential power output.

The short answer to your question, Yes. More than likely that motor will work well enough imho.

At 3s (roughly 12v) the 8 45 is spinning 23k rpm. On the 1900kv.
The smaller 6 3 would be turning about 28k on the 2300kv motor.

If we take no mechanical losses into acount the 1900 kv on an 8 45 would be doing nearly 100 mph and the 6 3 on the 2300 would theoretically be doing just over 80 at 12.5 volts....
(Edit, fell asleep before i could finish lol)
That tells us nothing of actual power of the motor, but it at least gives a ballpark idea in terms that are a little more relatable.
Given how light that model is, even with a slightly smaller motor, i think it would be fine on an F pack. That being said, its probably cheaper to find a banggood motor and esc for something like that, though you may have to solder the wires...

 

[Crunchybananas]

that F pack motor is slightly smaller and higher kv, so it probably can't run the same size prop at the same number of cells. How many cells does your kit ask for?

It says 2 or 3 cells.

 

[TheFlyingBrit]

Simple rule is a higher kv will give you increased speed, whilst a lower kv provides more thrust. When model aircraft designers specify the motor, ESC and prop for a model its usually through testing and optimisation, that's how they come up with a specification. That specification will be the optimised set up for that particular plane.
They sometimes throw in battery options ie 3s or 4s but then specify a particular prop size depending on your battery option eg a 4s will always use a smaller prop than a 3s battery.
To answer your question, yes you can play around with Motor and prop options (within the same ball park of the original spec.), but be careful they don't compromise the flight characteristics of the model by being too far away from the original specification.

 

[Hondo76251]

It says 2 or 3 cells.

If you go with the F I'd say run 3 cell

 

[bisco]

a lot depends on how you plan to fly the model as well.

 

[Bricks]

a lot depends on how you plan to fly the model as well.

this motor
http://www.valuehobby.com/power-sys...outrunner-airplane/2206-1500kv-outrunner.html

and this ESC or similar since this one is out of stock.

http://www.valuehobby.com/power-sys...irplane-heli-esc/hobbywing-skywalker-12a.html

total cost about $20





If you want to actually 3d then you want the lower KV and larger prop.

 

[TheFlyingBrit]

So A very nice guy gave me a elitemodels 8mm epp acrocub kit, but it is just the foam. it recommends a 2206 -1900kv motor with a 8x4.5 prop but I thought maybe I could just get a flitetest powerpack and not buy things separately. The powerpack F has a 2205 2300kV motor with a 6x3 prop, and I am not sure if that is ok for this plane. I thought maybe because the motor is similar size. if this is not the correct motor, should I buy everything separately or is there another pack I can buy? thank you!

EMAX ECO SERIES 2207 1900KV 3~6S MOTOR
Worth a look at they are roughly £10 ($13.89).
5" to 6" prop
Another option is the :
Brotherhobby VENOM 2206 1900kv 4~5s MOTOR
A touch more expensive at £14.

Both for sale through Banggood.

 

[Merv]

Think about a transmission.

High Kv generally use smaller diameter higher pitch props. Resulting in higher top end speed and lower thrust at low air speed. Just like a high gear in a transmission.

Lower Kv generally use larger diameter lower pitch props. Resulting in lower top end speed but greater thrust at low air speed. Just like a low gear in a transmission.

 

[bisco]

that's good info right there, thanks!

 

[Ketchup]

What Merv said is very true, but you should also watch out for another thing. Sometimes with quad motors you might see a lower kv, but the motor would be designed for use with a larger number of cells, making it a motor that still spins quickly. For example, the ones that @IanT linked have low kv ratings around 1900, but they are made for use with 5 or 6s lipos and therefore are still made to spin a small prop quickly rather than a bigger prop more slowly.

 

[Ketchup]

After looking at your plane, while I think it could fly off of an F pack, you will get much better performance and flight characteristics with a lower kv motor spinning a bigger prop. It would allow the plane to fly better in its intended speed range (slow), which would make the plane better to fly.
Also, the acrocub looks like it is a twitchier plane made for more 3d acrobatics and stuff like that. If you are a very new pilot I would recommend trying something easier, and hopefully by the time your skills are up to match this plane you would have the knowledge to pick out your own parts for it.

 

[JetCrafts]

depends

 

[bisco]

oh, i started using those with social security and medicare...