RC India

RC Models => Electric Planes => Topic started by: kushagrgoyal on April 03, 2014, 11:39:39 PM



Title: Suggestions for a scratch build
Post by: kushagrgoyal on April 03, 2014, 11:39:39 PM
I am new to this hobby and this will be my first scratch build. I've built one versa wing and one KF aerofoil based rctestflight's wing, both did not fly.
The only material available to me is 8mm biofoam. I also want to make this plane for fpv.
i bought these electronics for the versa wing -
Hextronik Bluw Wonder 1300KV 24g brushless butrunner
two 9g turnigy servos
2200mah 3s 20c lipo
500mah 3s lipo for 900mhz sony ccd 450tvl and video tx
8*4.5 SF prop and 8*6 DD prop
birdie 20A ESC

I thought that my previous build were too heavy for this motor-esc combination so, I can upgrade it if needed. Please suggest some FPV platform that can be built using 8mm biofoam.
Thank You


Title: Re: Suggestions for a scratch build
Post by: K K Iyer on April 04, 2014, 12:02:59 AM
@kushagrgoyal
You may like to see replies 8-15 on this thread
www.rcindia.org/electric-planes/scratch-built-foam-(hd-thermocol)-telemaster-for-2014-sweepstakes/msg178368/#msg178368 (http://)


Title: Re: Suggestions for a scratch build
Post by: manojswizera on April 04, 2014, 11:01:31 AM
You are right kushagrgoyal, the motor you choose for versa wing is too much underpower.
lipo was also very heavy.


Title: Re: Suggestions for a scratch build
Post by: kushagrgoyal on April 04, 2014, 11:05:41 AM
I used the recommended parts list from the pdf plans, but the motor still is small.

I have no idea as to what difference there is between a 24g brushless and 50g brushless, I've been searching youtube but can't find any info. They only explain KV.


Title: Re: Suggestions for a scratch build
Post by: Swapnil on April 04, 2014, 11:56:58 AM
@kushagrgoyal
Wattage and thrust are some parameters apart from the kv rating that you need to look into. Obviously, the heavier motor will give you better thrust. More thrust means easier handling.


Title: Re: Suggestions for a scratch build
Post by: shobhit17 on April 04, 2014, 12:33:16 PM
Well friend,
This a common misconception or a not well understood case by most newbes.  I too had this confusion about what motor to buy... OK here is what I understand of it...
1.   The figure per kv generally corelates to the rpm per kv of the motor.... higher the figure the higher the best operating rpm of the motor...  Higher the best rmp means that your motor will run at a higher rpm though driving a smaller propeller.  In case the kv figure is low... something like 700kv.... it means the best operating rpm of the motor is low and it will drive a bigger propeller for its best output though at a lower rpm.  I prefer a low kv motor driving a bigger propeller.
2.   The thrust output of the motor is what decides what weight of a model it can carry along well enough.  A motor of same thrust (say 01 Kg) can be of 700 kv or 2000 kv.... all it means is that the thrust of the motor is 01 kg but the first one drives the prop at 700 rpm per volt (or whatever) and the second one at 2000 rpm per volt.  the catch is... for the utput of 01 kg for both the motors the first one will drive a bigger propellor and the second one will drive a smaller propeller (say 10x6 for the first and 7x4 for the second)

if I am not correct someone please give the correct information here..........


Title: Re: Suggestions for a scratch build
Post by: iwincar on April 04, 2014, 03:17:19 PM
Shobhit nicely explained. Pl suggest on my mix of electronic on this forum named 'electronic set up for rc electric


Title: Re: Suggestions for a scratch build
Post by: allthatido on April 04, 2014, 03:43:46 PM
@kushagrgoyal 

I think you should first drop the idea of building a flying wing and FPV. First learn to fly an rc plane and subsequently add complexities. Since you are new to this hobby I suggest you build a high wing trainer plane such as blue baby.

The lipo you have chosen for this setup is very heavy. And to that you are adding a Vtx/rx and another lipo. Your model was bound to be heavy. Getting rid of all the unnecessary components and a high wing trainer should be a good starting point for you.

Ankur


Title: Re: Suggestions for a scratch build
Post by: kushagrgoyal on April 04, 2014, 04:14:48 PM
@ankurkaul17

this is my first plane, i have a small quadcopter that can be flown around so i wanted to make fpv plane directly.

i have dropped the idea of a wing, but I'd still like to build an fpv platform to which i can add fpv gear later. i am not aiming for a long range fpv but i do want something that can fly for about 20 mins or so.
i chose the above electronics because these were the mentioned recommended electronics in the pdf plans of the versa wing.


Title: Re: Suggestions for a scratch build
Post by: shobhit17 on April 04, 2014, 04:42:39 PM
please listen to Ankur.... learn how to fly and control the model in unusual attitudes before you allow it to be in the air with your costly FPV equipment.  Crasheh do happen and they all cost a lot of time and money... they can set you back in time (loss of the model) and a lot of money....

We all must first learn to fly the model really well.... if possible do basic aerobatics on them before attempting to fly the FPV........


Title: Re: Suggestions for a scratch build
Post by: allthatido on April 04, 2014, 08:05:12 PM
The hextronic motor according to the website gives 400 grams of thrust with 3s and 8x3.8 prop. You have to keep that in mind. FPV with the same setup in bleak. Suggest you make a trainer plane and learn to fly.

Then make another fpv plane with improved electronics.


Title: Re: Suggestions for a scratch build
Post by: v2 eagle on April 07, 2014, 05:51:53 PM
2200mah lipo is the real culprit.
 it is useful if the plane AUW is around 1.5kg. not for a 400gms plane. go for a 100mah lipo to save weight.
also get a motor that gives around 800gms of thrust for a 3s lipo. forget about KV rating and wattage for now(they are really useful stuffs to know about and are really needed in the long run), just go with the recommended ESC/Prop/Lipo for now and make sure the AUG comes around the max thrust of the setup.

Ashok.P