RC India

Hi
I am working on an Rc plane which has 60" wingspan and 45" fuselage all built from foam board. The problem is it weighs more than I planned or I saw online.
The current weight of this plane is around 1.5-1.7kg without the motor.
I want to know which motor would be best suited for this plane and also how to choose one. I figured out 2814 1000kv or 3536 1100kv would be helpful but again two different motor size is confusing me. I read few posts related to this but I wasn't satisfied so I decided to ask again.

Also, how does motor Kv rating affect the plane because I have seen few motors datasheets and noticed motors of higher kv can provide almost same power as lower kv, So, How one decides exactly how much kv to use?
plus wing area is about 300 sq.inch, So is it sufficient considering the plane weight?

@aman48811,
Welcome to the forum.

You may need to reconsider your plans for several reasons.

A 300sqin area, 60” span model weighing about 2kg, is a table top display model.
Perhaps only an expert RC Jet/Aerobatic flyer will be able to fly it.
For a beginner, a 60”span 300sqin model needs to be in 5-600gms range...

A 2814 motor and a 3536 motor are vastly different from each other, not comparable...

This may be of some help:
http://www.rcindia.org/electric-power/iyer's-tech-talk-how-much-power/msg196376/#msg196376

Best wishes

Hi, you could check my post incase you find its useful for your application let me know
http://www.rcindia.org/for-sale/propulsion-system-for-sale/

This is by far the most detailed answer I have read. It was indeed very helpful
Thank you Iyer sir!
also Since I have already made the plane and only the electronics is left I wanted to give it a try and see if I can get it up flying.(maybe only take off and landing)
I did the mathematics as you have suggested in your post. Here is what I think is needed, correct me if I am wrong
plane weight (1.5-1.7kg) power (300-350) watts (100%thrust)
now going on to calculate the stall speed for (300 sq.inch wingspans and weight of 1.6/7 kg) it comes out to be 22kmph
so the required speed would be around 60ft/s or 90kmph
now talking abt pitch if I go with 5" pitch 12000rpm is required and if you convert it to kv keeping in mind the 0.75 efficiency rate, 1400 kv should do the work.
Dia of prop well 10" would be good I think.

Considering all this I think this motor should do the work for me
http://www.rchotdeals.com/480-size-brushless-outrunner-motor-a2814-6t-technical-data/

please see and give you valuable feedback sir! thank you

You PMed me the same msg. Saw that first and replied by PM...

Meanwhile you can see this video posted by knvshrm, to get an idea of a light model...
http://www.rcindia.org/tools-materials-and-building-techniques/styrofoam-in-kerala/msg287191/#msg287191

@aman48811,
Never heard of rchotdeals before.

If you’ve already built it, please post some pics
So that we can check out other issues too.

Like layout, dihedral, tail size etc

Here is the layout:
https://docs.google.com/file/d/0ByhtTaHuhLwvb3luRDJhMjdkTEU/edit

again I messed up the weight this was supposed to be a 1kg or less. So I might have to remake the wing and tail section. please give your feedback.
No, I am just using the rchotdeal website to check the motor specs they have night charts and graphs which gives detailed explanation abt which prop size will give how much thrust. So, I just wanted to know whether or not 2814-6T 1400KV motor with 1050 prop will be able to lift up this plane.

In the picture, you can see my friend holding the plane for me.

why is the fuselage so long?
And why is there upthrust in that motor?  :headscratch:
The wing appears to have anhedral as well.....

It's 45" only
Wingspan is 60"

please reply to these as well.

Sorry I missed those

No, the uplift and anhedral were not intentional it was corrected later on!
Wings are anhedral bcz they are too long and joined at the centre so it's kinda inevitable. any advice on this is welcome :)

Also right now the main problem is the motor selection and whether or not this plane can fly?
Though last night I was wondering what if I make it Twin motor. So give your opinion abt this too if you have any idea?

I have two of similar size (64”).
The Green one (Sunbird) weighs 450gms with 80gm 1300mah 2s lipo. Flies gently.
No ailerons, only rudder, elevator, throttle. Polyhedral. Climbs at 50watts, cruises at <25watts.
The White one (Pilatus B4) weighs 900gms with 90gm 1000mah 3s lipo.
Has ailerons and very little dihedral. Has a 300watt motor, but rarely exceed half throttle (~100w) to save the lipo and avoid exceeding 100kmph!
Flies like a jet, fully aerobatic. Needs about 500ft space to land!

Your model (if it’s the ExAir Photon) is supposed to weigh ~850gms including 200gms for a 3s 2200mah lipo. Not sure why yours weighs twice as much...

Regarding motor, you could start with one of these:
Turnigy 2826 2200kv with a 6x4 prop
Turnigy 2826 1400kv with 8x6 or 9x5
Turnigy L2210 1650kv 8x6 or 8x4
Emax CF2822 (1200kv?) with 10x5, 10x6, 9x6

These are all in the 200w range, which should be enough to start with.
A 2836 with 9x6 or 9x8 later.

For 350w or more, please seek advice from Rai sir (sanjayrai55)

Lastly, may I suggest that you save this one as your second model, and start instead with a much lighter model like Easystar, Skysurfer etc.
Best of luck.
Regards

Here’s a pic.

Iyer sir,
That B4 looks beautiful!
you made it?

@aman48811
as Iyer sir said,
keep this as your second plane.
i suggest you go for the FT Stroch or the FT simple cub.
both are great planes.
your plane will be way too much for a newbie.

Regards

Okay Sir!
Will build a new one then.

Thanks for the suggestions will start working on it!