[Opcod]

Yess thanks a lot Wayne.


Also, : hillmanr2 , do you have any hint about the prop pitch... ?

The main trouble that i have is the maximum size that i can go on the 2826 and 2820 is about a 11x6 and it's also my maximum, 11 inch for have enought clearance.

The plane seem pretty hard to fly, at many many config, Motocalc always answer me that i will be a long take off or medium and can be hard to fly if wind is present... haaaa

I will make more search to find out the best also.

[hillmanr2]

how difficult would it be to extend your landing gear to swing a 12 inch?
either that or you may have to go with a 4cell or a glow engine.

[hillmanr2]

you need to find a high kv motor. that is rpm per volt or run a 4 cell pack. I figure you need 12500 to 13500 rpm with a 11 diam prop. the axi is 910 kv. multiply that by 11.1 3 cell and you get 10101. I don't think that is enough. this is the same with a glow motor. A 4cel pack will give you enough but now you are getting heavier. Decisions, decisions.

[Opcod]

hehe

of course, it become all the time more eveier.. but also, one big 4s2p can be good.
Also, i will try tomorrow the 4130 with a 6s4p. i will check what the result can be..

Also, i can put a another inch in the front wheel, but at the landing, i will got more problem and if the plane jump, i don't whant it to crack the prop and the engine.. But i will check that more.

[4*40]

Your motor is too big for the plane.The best motor would be the Axi 2826 10.At our field a fellow flys an Goldberg 40 size chipmonk converted to electric weighs 6lb ready to fly.He uses the Axi 2826 10 and 12 Nimh sanyo 3300 packs.Flight times are around 7 minutes lots of power etc.If you wanted to use lipos a 4s 2p pack would be best.With the Axi you need batteries that can handle 40 amps continuous.If you use the 4130 motor I hope you don't lose your motor in flight it might just pull the motor mount from the plane

[Guest]

For all those using kV to calculate RPM...this is a very rought assumption. kV values are spec'd at zero load.....loaded values can drop significantly.

Its very misleading to say you will get X rpm because you run a 3s pack on X kV....voltage of the pack under load and how the kV changes with load can have serious impacts on the final rpm.

I think the first thing that needs to be established is.....

How much performance do you want out of the plane? Unlimited vertical...lazy flying etc, because its Cub like I get the impression the performance is the latter.

Once you know that its easy to establish how many w/lb you want to run at....from there its easy to pick a motor/batt/prop combo to acheive that.

4130 is a bit much IMO 2826/10 on 4s4200 mAh TP Prolites (15C packs) is probably a much better choice

[Canhos]

Opcod.

I'd do as 4*40 recommends. I don't know him personally, but he fly's with guy's who have been flying electric planes almost exclusively. His advice is based on actually flying a plane, where Motocalc is a good starting point. It will mean you have to get a smaller motor, but to do what you want, that is what will be required.

My numbers were just an example, I had only taken a quick look at the Axi line to get a reference to see what is going on with your current setup.

Good Luck with your project. I hope it gets off the ground!!

Mike

[Opcod]

Ok

So i have try the 6s4p setup over my Axi 4130/20. So it's hard to keep in my hand for not the plane goes into the wall. But with a 4130-16 or 4120, i think it can be more efficient. Also, i put it on full throttle but i don't feel it was too much power for the plane. The stall speed will be very closed to the max air speed. But on MotoCalc, it say that the plane cannot lift from the ground..

But for sure, the plane can be very more interesting with the 2820-12 and with MotoCalc, with 1 3s4p lipo it can fly well.

But, i look it i put the Axi 4120-14 , and with a 6s4p, it can be very good and maybe efficient.

MotoCalc told many time : The static pitch speed (49mph) is less than 2,5 times the stall speed (21mph), which may result in reduced performance at typical flying speeds and a low maximum speed. This situation is usually acceptable for an electric sailplane or other slow-flying model.

But with the 4120 : The static pitch speed (69mph) is within the range of approximately 2,5 to 3 times the model's stall speed (25mph), which is considered ideal for good performance.
and : The static pitch speed (69mph) is within the range of approximately 2,5 to 3 times the model's stall speed (25mph), which is considered ideal for good performance.


So it's now more harder to understand... the 4120 seem to be way better...

Thanks again.

[Wayne MIller]

Hi Opcod,

I would suggest you go to HELP in MotoCalc, and select email technical support.

Explain to them what you have, what you entered in, what you want and ask them for advise.

I do know the program is "conservative", and you may want to ask the technical support for a better explaination of the answers you are getting - I think it will help a lot.

MotoCalc is located in Canada and are very helpful.

Fly4Fun,

Wayne Miller