so..Aru..we will meet a nice aircraft...have a nice flight..so try like this...while making a high wing aircraft, first of all we have to determine the cord( length between leading edge and trailing edge).then take the wing span in to 4.5 to 6 times that of cord length.from leading edge to nose you can take 1 to 1.5 of cord length.then take 2.5 to 3 of the cord up to the horizontal stabilizer..not full but up to moving surface.if your fly is a slow one you can choose slightly big elevators and rudders...and make sure your aircraft is nose heavy...a nose light aircraft never fly correctly...if it goes too heavy it will be too tough to airborne...about a 10 to 15 degree is enough...and fix a nice light landing gear..so you can try it from ground by takeoff run...so you will get some idea about the nature of the aircraft...and you must try to alter the angle of attack of main wing by adjusting it from base.if you are using a high lift aerofoil there must be a chance of balooning...so try and make it correct...have a nice flight...

this  is  what every new bie builder needs , the idea of calculations , if you were there when i started building , i would have  flewn early  and would have save some money .

thanks roopesh

Vineet..most of the crashes happens because of the panic...for an example, imagine your aircraft is approaching you from in front of...and it leans in to one side...we instantly inputs the stick to correct it in a hurry manner and yes in to the same direction that aircraft leans...then..lost...instead allow the aircraft to climb up around 40 to 50 meters..and take all fingers from the sticks...if your aircraft is perfectly balanced it must fly in straight manner...if not you can make corrections by adjusting the trimming controls...so whenever we sets a control surface connect and switch on the receiver and transmitter and make sure the corresponding trimmer is set at "0" or in center.if not later it will be far difficult to make some corrections.and one of the most important thing that we have to consider that the angle of the motor.we simply fixes the motor in a straight line...finished...yes, you can if you are too experienced flyer...so, there is an easy remedy..fix motor about 2 to 3 degree towards starboard side of the aircraft..and yes also in to down about 2 to 3...and my experience shows that using a low pitched prop eliminate the problem of torque reaction...an increased rpm will reduce the load to the motor also..but never select too small prop for a big aircraft...and i learned that if the wing is broader..more stable the flight will be...but we have to increase the size of the control surfaces also...a simple trial and error method is far enough to make a good flyer...

we must give a little angle (dihedral or anhedral) up to 2 to 3 degrees..overmuch angle will make more drag and it will be more difficult to take a turn...when we make an electric flyer we have to consider the motor torque..dc motors are far powerful and all it are crispier in response..so when applying throttle we must take care to avoid sudden opening of throttle..many ESCs are programmable to avoid a sudden acceleration..a good calculation is for a good high wing trainer is about 40 inch wingspan.a three channel is enough for a less windy day...at beginning we can choose a high lift aerofoil according to the respective Reynolds number..when you got the logic to fly an rc aircraft it will be easy to follow, just like we learn to ride a bicycle...

its easy to find the CG point of your aircraft..i will give you a simple method to find the CG..this method may odd but my experience shows that it works well..place two stiff metal scale under and over the wing.hold firmly..and you can see a particular point, towards the trailing edge, from leading edge,is in to maximum thick..in a good design that point will be almost within 3/1 of the chord of the wing..for example,if the wing cord goes to 3 inches the Cg point will be about 1 inch from the leading edge..so you can make a simple CG balancer by fixing two reapers on a table, and making sure both ends are parallel to each other, by the help of a spirit level.then we can place the aircraft over the sticks, pointing and resting to the CG point that we calculated.in this case the aircraft must be in a nose down situation about 10 to 15 degree according to the nature of the aircraft.if it stays nose up...time to do some thing..we must replace all weight matter towards front...until we get a perfect nose down...we must try maximum, to balance the cg with materials with aircraft itself, and must avoid adding more additional weights to it...if your aircraft is nose heavy according to the criteria it will fly....

what is your power setup?
roopeshkrishna makes really good points

Naattu..when i started my aero modeling around 87 there wasn't any option to follow...until i saw a person, was an instructor, in NCC not in my, (i was in army NCC) but air NCC,and i started to wander behind him..at first he raged me and kicked me off many times..but at last he took me as his student...and at that time was only control line models and wasn't any RC...i still remember those engines were based on ether and kerosene and engine was from Aurora and Sharma...it was a lightning experience at that time...from him i learned much in aero modeling..i still holds some of those engines in immaculate condition as my officer gifts to me...

Quote from: naatumach on July 22, 2011, 11:49:20 PM
what is your power setup?
roopeshkrishna makes really good points

emax 28-12 1534kv motor
hk 25-30A esc
rhino 3s 750mah lipo
9g servo

Aru..i am giving you a hint about the CG balancing...you can see a RC plane here, is a proven platform is Paragon, and i taught ample of students with this kind of aircraft...you can see how the aircraft stands...nose down...?  sure...and if your CG is ok..it will fly even if you use a flat surface instead of an aerofoil...

Arun..1.5 Kv brushless is far powerfull..there must be a high torque reaction..especially at high accelerations..so choose a less pitched prop about 9x less pitch...then try...its easy to make an rc plane from the thermocol, by buying a sheet of it, in to 3 feet X 1.5 feet.after marking the aerofoil shape it with emery paper and season it once..it will be strong enough to withstand all G forces in RC flight..you can also reinforce with balsa strips, or can reinforce with wooden reapers reamed in a circular saw in to 2mm X 2mm strips...will be lighter and stronger....your tail plane must be under or over the main wing to avoid washout vortex..if your tail is situated in washout it will be inactive in flight...so understand some basics...design...make...fly safely...if your calculations is ok..you can take any shaped aircraft in to air...have a nice flight...

@roopeshkrishna -
Thats great. Even when i started i had no one as a guide. I only referred to internet.
After about an year i found rcindia and found a sea of knowledge and people willing to share knowledge.
I personally still dont know anyone who flies RCs. All i do is from my instinct, internet,  rcindia and calculation.
I still get my kicks from reading the posts from "http://www.rcindia.org/servos-gyros-and-all-electronics/why-do-we-require-a-servo/"

@arunkumarnk :
Internet says
-Enough power for my 350g Delta with 3s HC Rhino 1250mAh and APC e 7x6. That's enough for vertical climb.
-Perfect size with a sport 7X6 prop at 17A to carry a 15oz (425g) plane at 70 MPH.
-Stryker 134kph 7x6 apc style prop 30amp esc 2200mah 20c approx 15min flite time full power all the way... ( a stryker weighs 580g)

What i can infer is that if your a/c weighs below 250g it should fly.
Which prop are you using?

Quote
if your CG is ok..it will fly even if you use a flat surface instead of an aerofoil...

true, but having an airfoil REALLY helps. It reduces a lot of load on the motor, and can make quite a difference in flight.
Aptly put by RCPowers its a conundrum
- If you have Less power
- You add bigger motor
- You increase the weight
- You need more power

I have a few more additions to it
- You increase the weight
you reduce the thrust to weight ratio
you increase the wing loading

The best way to break the loop is an airfoil.

Quote
its easy to make an rc plane from the thermocol,

standard thermocol available in a store? with that huge grain size?

Aru..i will give you a guide for a nice fly...first of all collect two or four soft wooden reapers that we used in electrical wiring.choose a good straight one,must be long enough in to 30 to 35 inches. make the main wing from thermocol, in to a thick high lift config. a high lift aerofoil..?  don't worry..buy a 1 inch thick sheet, and cut it in to 40 inch long and 7 inch wide.start to scrub from leading edge, and round it, just on top, not on bottom...turn to trailing edge..shape it even more thinner than leading edge...after making sure the overall shape is in, cut the wing in to two..slightly paper top insde of each wing, so you will get a slight inner angle.apply white glue to the surface and stick together, while retaining the tips of the wings above the parallel line.leave it overnight...after make sure wing is ok and no warpage...
season the wings...so it will become stiffer...make a tailplane and rudder accordance...then fix it all respected places...place all servos and radio over the wing.connect the stabilizer and rudder with fishing lines in push and pull manner...so it will not loose control..and will be weightless..you can simply fix the motor to the wooden reaper withan aluminum strip..place battery just behind the motor, with some good heavy duty rubber bands..so you can simply adjust the CG, by displacing the battery-pack fore and aft...you must fix a landing gear to your aircraft..dont worry..buy a cheap Chinese toy car, so you can simply take the wheels and can fix it by two bicycle sopkes, by making two holes on the wooden reaper...then...ok...time to fly...

Naattu..nice to hear your experience....its too inspiring...and happy to find one like you...

Naattu..its easy to make a wing or a structure from a standard thermocol...a sheet costs around 20 Rs...but if you want to make it stronger..just season it after shaping it...will be stiffer...than we imagine....i am making crafts more than 60 inch spans....nice flies....

How to season it?

You can use this airfoil for reference.
Draw something like this on the edge of the wing to get some reference in shaping.

Naattu we will meet tomorrow..i have medicines...and mother is shouting..time to sleep...good morning...

Quote from: naatumach on July 23, 2011, 01:04:41 AM
...
You can use this airfoil for reference.
...

Vaibhav, the airfoil in your pic is a flat-bottom. I've come across many articles that say 'don't use true flat-bottom airfoils for anything'. What is your experience with these?

Quote from: roopeshkrishna on July 23, 2011, 01:06:39 AM
Naattu we will meet tomorrow..i have medicines...and mother is shouting..time to sleep...good morning...

I guess that happens with all of us!

Quote from: roopeshkrishna on July 23, 2011, 12:49:12 AM
..its easy to make a wing or a structure from a standard thermocol...

I'll second that. Thermocol can be really useful at times, even the thick-grained ones. But that comes with experience...

Arun, before you start again, I'd suggest you really go through ALL the articles on this site, it will refine all your knowledge and ideas regarding aircraft and RC:

http://www.airfieldmodels.com/information_source/index.htm

Good morning Friends..Swapnil, my experience about using a flat bottom airfoil is, some trouble in a high windy day..some ballooning happening...so i started to grind a little just under the camber of leading edge...so will be a balanced platform..ok..from the inspirations all works going on here i started a work on my new biplane by yesterday..now the wings are dried...and seasond...its nice and stiff...its based on my imagination, but willing to fix it with WW1 colour codes and decals...her wingspan is 44 inches..so i will post a detailed log here, so i hope it may help some of my friends..back pain and rain is disturbing me a lots..but i will finish it within time...within that time i hope, that my ordered brushless combo will arrive...i got a radioset from one of my friend from our forum..and waiting for some servos..as my own..so..she will be a nice one to wrooommm....

swapnil..thanks for the links...i wonder how informative you are...thanks once again..

 
Being resourceful is one of the many important qualities that make modelers successful!

yes..sure Swapnil..you are a nice one...thanks for the guidelines...i appreciate your self effort to acquire knowledge..thank you..