What should be the ideal thrust to weight ratio ?

Started by Siddhant_Sangai, June 14, 2014, 12:37:41 PM

Previous topic - Next topic

0 Members and 1 Guest are viewing this topic.

Siddhant_Sangai


Hi, I am new to Rc

Just bulit a 530gm foamy. Was wondering what should be the thrust to weight ratio to make it fly.
i am getting a thrust close to 610 gm.

Plz help guyz...!!

manojswizera

thrust you are getting is more than 1:1, its more than sufficient for your plane.
Be gentle on the throttle.
Russ-40 Trainer, Mr.moss, Pushler, Skysurfer, Mugi , F-22, Red swan, Xtra-300, redfury, flying mantaray.

Siddhant_Sangai

ThankYou.
I feel the same hopefully it should fly.
good to see rc lovers in regions near nasik

K K Iyer

@siddhant_sangai
Thumb rules for thrust:
Trainer with low wing loading - 100watts/kg or 50% thrust/wt
Mild aerobatics - 200watts/kg or 1:1 thrust/wt
Fully aerobatic - 300watts/kg or thrust=wt x 1.5

But that is not all - you need an appropriate prop.
A large dia with small pitch (eg, 10x4) will give lot of thrust but low forward speed.
At 9000rpm, or 150 revs/sec, a 4" pitch prop cannot exceed 50ft/sec, or 55kmph.

Whether this is safely above the stalling speed or not depends on the type of model and its wing loading.
A glider type will fly with low power, low rpm, low pitch.
A jet type will need high power and high rpm and/or high pitch.

For a more specific answer you need to post a picture of the model and give details of the motor, prop, ESC, battery, wing area and all up weight.
Best of luck.


Siddhant_Sangai

@KK Iyer

Sir, I have used an avionic 2836(1120KV) motor ordered from Rcbazzar.
I calculated its thrust on a somewhat test bench.
Prop is 9x4.7E
battery is Zippy 1300Mah 20c 3 cell lipo.
Esc is turnigy multistar 45 amp.

Since my budget is low i m going for mild aerobatic. its my first flight just want it to see flying.... ;D ;D

Siddhant_Sangai

The flying weight is around 530 gm.
i have no idea about its wing area.
the thrust i have calculated is around 610 gm on my not so scientific test bench.

Siddhant_Sangai

here are some pics...

K K Iyer

@siddhant_sangai
Did you not look at the specs for your motor on the RC Bazaar site?
It says:
PROP – 9x4.7E
● Get 1100gms Thrust

So you are not going to be short of thrust!

Hope you have build the model from a proven design so that you know the suggested position of the centre of gravity, the neutral position of the control surfaces and the recommended control throws.

May not be suitable as a first model. What is needed for the first flight is not aerobatics but STABILITY (ability to fly by itself on releasing the controls)

Siddhant_Sangai

Sir, I did view the specs and that's why i did buy that motor.
But i wanted to test it myself so that i could confirm it.
Yes i have built the model from a proven design.
Thank you for correcting me now i ill focus on stability.

K K Iyer

Best of luck for maiden flight.
Pl recheck CG position. May presently be too nose heavy.

Prashant_G

Hi Siddhant
   i am also from Nashik, i think that the model you have built is very nice  :goodjob: but difficult to fly for beginners,it will be very fast, you'll need lot of practice on simulator... here is my attempt of making rc plane completely from scratch, my be helpful for you...  http://www.rcindia.org/electric-planes/home-made-plane-%27ice-cream-sandwitch%27/msg167095/#msg167095

Siddhant_Sangai

@Prashanth_G

Thank you....
looking forward for help frm you.

Prashant_G

If there is any RC activity, i'll definitely call you, i hope that we'll meet soon. :)