I cant call myself a beginner now. I have started off, built, crashed and taken off finally.
Here are some questions which i believe only experience can answer precisely.
Here are a couple of questions which intrigue me-
1.How important is an aerofoil in terms of RC planes?
2.If working on only 3Ch. What do you prefer Rudder,Elevator or Elevons?
Because Rudder-Elevator can only control yaw and pitch and the plane can still roll out of control. If I use elevons then i can roll and pitch and the plane will not go out of control.
Obviously we can control the Roll with dihedrals which brings me to the next question.
3.i.How much dihedral angle is needed?
 ii.How to cut a precise angle?
iii.How to hold and glue a precise angle? (one way is to use bent rods but still they are not symmetrical)
iv.If dihedrals are so tedious why go for them if making a scratch build a/c.
Even after building the dihedrals can it compensate for the motor's torque and the a/c balance issues caused due the placing the battery on a little offset from the center of the fuselage?
4. After building my fair share of a/c i found a/c with "large" wing surface areas to be more forgiving than the rest. They seem to have a little parachute effect. Any comments?
5. Using depron which thickness do you find most reliable? The one which is best suitable for you in terms of flexibility and load bearing?
I have only used 12mm because i can sand it and i have a larger surface area for the epoxy to hold.

Regards
Vaibhav

Q1

Ans: Airfoil is important in RC but it depends on what scale of RC model u r trying to build, me and my team have designed airplanes from few centimeter to few meters in wing span for internationl competitions...

for low wingspan airplanes with very low Reynolds number (Re Number) a flat plate is more than enough coz the flow is higly laminar an it does not contribute to profile drag, and none of the traditional airfoils are designed to operate at such low Re number.

when designing wingspan upto meters we have to consider the final weight of the airplane, how much lift the wing offer, how much is lost due to wing tip vortice, skin , profile, Induced, Drags. so if the intention is to consider an airplane for a competition or actual marketing u have make it to perform at the highest efficiency levels.

When it comes to the hobby flying, factors like time, skill, material, cost ....come into picture so then u decide if u have to airfoil the plane of not.

Q2

Ans: Most of the High wing trainer have Rudder - Elevator for control mechanism, and if u have noticed trainer like axn floater, multiplex easy star, they are not sensitive for roll, but if u consider pure delta planform u are forced to have elevons. so its a matter of which planform u are flying and innovativeness in controlling ur a/c!

u can build a plane which is not roll sensitive, ter's no compulsion that one has to have dihedral to control the roll.

Hi jatayu
thanks for the answers.
Is your display pic CFD or Structural analysis? its too small for me to decide.

Q3

i) Involves Mathematics! as a Thumb rule i USED to put 1-2 Deg dihedral in plane upto 32 inch in wing span and 2-4 Deg dihedral in planes above 33 inch!( Expert's comments needed)  now i am yearning to make my plane as unstable as possible!

ii) and iii) Question not clear!   are u talking about bevelling to attach control surface??

iv) beginner scratch builders are advised to put in dihedral so they can control the a/c using rudder only!
if u say dihedral is tedious isn't scratch-building more tedious??

Pic is of CFD anslysis of a Delta Planform 

CATIA or FLUENT or ANSYS?

Designed in CATIA
Pre Processed in Pointwise
Post Processed in Ansys Fluent v12

Quote from: Jatayu on June 21, 2011, 07:53:08 PM
Q3
ii) and iii) Question not clear!   are u talking about bevelling to attach control surface??

if u say dihedral is tedious isn't scratch-building more tedious??

I am beveling but i cant bevel evenly, the only way i can think of an even bevel would be using a jig or a fixture.
Scratch building isnt actually tedious, but it becomes becomes tedious if one doesnt have proper tools, like me. But its all worth it.
I build a/c to feel the dynamics, the 6 degrees of freedom. I like to build, fly and then change the design and fly again.
I dont want to fly a/c, i want to make it fly. Once it flies im satisfied, then i have two goals, stablize the flight or change the planform.

Quote from: Jatayu on June 21, 2011, 07:58:39 PM
Designed in CATIA
Pre Processed in Pointwise
Post Processed in Ansys Fluent v12

WOW!
That is cool!
I love catia, but now i want to learn fluent.
I am very comfortable on catia . I wont say im good at it.
Last time i learnt and worked on catia DMU.
I will try to learn fluent next. but im running out of time, i have to study for gre and college too and also lots of college work

Hope u knw the pre requisites for CFD??? all the results in CFD depends on meshing more than the solution, validating the solution is the major task in simulation softwares.. Which sem by the way ? me in 5th!

To add it all up there is no one in my clg interested in aerospace. I am the only one.
That ways i dont have much guidance or clg motivation.

Quote from: Jatayu on June 21, 2011, 08:13:13 PM
Hope u knw the pre requisites for CFD??? all the results in CFD depends on meshing more than the solution, validating the solution is the major task in simulation softwares.. Which sem by the way ? me in 5th!

Im also in the 5th sem. I will start with my fifth sem this august.
I dont know the prerequisites but i do know that it really depends on the meshing.

to make an unstable a/c i know you must have tried but still have you tried anhedrals?

Get hold of CFD by John D Anderson to get hold of the theory, turbulence modelling and stuff.... go through tutorials in kxcad.com for the getting hold of fluent.

Anhedral? nope haven't tried them... making a wing bend other way around is kinda difficult..

how is it difficult? bevel in the other direction. It actually the same process for dihedrals and anhedrals.
Thanks i'll surely check it out.
I did download loads of ansys and cfd tutorial series. But i need a good stepping stone.