RC India

Hi Guys ,
Another potential BOMB in terms of discussion, but should be educative .

I heard some highly knowledgeable persons in Aero say that in the case of  RC Planes the aero foil does not really add up to much.They quote the flat out foamies  to be living examples that prove them right .

I have no clue but would like to hear the technical take on this point .

Sai

What the heck is an aero-foil ?   8-)

well sai uncle i think you miss spelt it its airfoil and if you look at any thing that flies you need lift and the airfoil helps in that. this is something i learnt two years ago that is the longer path explanation of how does the wing work. but airfoil in foam planes too is necessary as you need a bit of the lift thats why they say sand out the leading edges .

I didn't mean that as a wrong spelling. Just wanted the discussion to start with a proper definition of what we are talking about.

oops sorry even i dont know then what is an aero foil  ??? ??? ???

Dear all........
Just a note..........Airfoil and Aerofoil are both correct where the former is the American and the latter is the British way of referring to one and the same object.http://en.wikipedia.org/wiki/Airfoil (http://en.wikipedia.org/wiki/Airfoil) this link has some info on the airfoil alias aerofoil. hope it is informative. {:)}
Edwin

hey thanks edwin uncle i did not know that now on to the importance of aerofoil

You are right Subu  Bernoulli's principle  ( http://en.wikipedia.org/wiki/Bernoulli's_principle )  but  does it really make a difference  in case of a small wing  ???

Then  how do flat outs fly  is it on thrust alone  ???

Edwin  that is an interesting link .

Sai

A bit more on airfoil...............
http://www.youtube.com/watch?v=3x9eDazOlkM
Edwin

hy sai uncle i did a bit of research on two flatouts and found out these seem to have an airfoil
in this first case it is the bent wing
(http://www.electrifly.com/flatouts/gpma1122-don-2.jpg)

in the second see the leading edge of the wing there is a carbon tube which gives it a small airfoil type also due to large wing span the the airfoil doesnot need to be large

(http://www.electrifly.com/flatouts/gpma1112-main-lg.jpg)

Edwin ,  {:)} {:)}
That is a fantastic Video and when you click their link to you tube they have quite a few interesting Video's like this one :
http://www.youtube.com/watch?v=5KWOzgGbFrw

Sai

Subu ,
The bent wing like the MOSS is a kind of aerofoil  termed as un-cambered .
This has higher lift than regular wings as the speed of air below and above the wing is made higher .
The slow stick is a classic example of this .

The question still remains does it make a major difference in a case of an RC Plane ?

sai

And yet some more on the infamous Bernoulli effect............. ;D
Its something that I jus love..... practical science.....
http://www.youtube.com/watch?v=olVJzVadiFs
Edwin

Edwin superb  {:)} {:)}

When it can make a difference on  a paper why not on a small plane right  ;D

hey guys a few months ago i did some work on airfoils i have a video which i made just posting it. it was just to check how the deodorants spray particles joined at the end of the wing

http://www.youtube.com/watch?v=IYIfjKIAxNE

Thank you Sir........
Its the encouragement that keeps us folks going on.....................
Edwin

Subu ,
That is cool , but still how does a full full flat out fly.

sai

well i am back to the testing bench with deo in my hand to check it out. and my exams are starting from monday so next week will be no rc infact from tomorrow itself. after then i will order my new slowstick and the new battery and some props too. the result i will post in some days but this question is something i am stuck upon

oh and thanks for the comment

Now about the flat foamies,
They do not entirely follow Bernouli, but are more biased to Newton, especially the Newton's third law (every action has an equal and opposite reaction) In the case of flat foamies, it is rather the angle of attack of the wings and the thrust generated by the motors that enable flight or rather lift. Thats the reason why when hand launching flat foamies, the are held at an upward angle, whereas in the case of an airfoil, the angle is not mandatory. Tons of info here:http://www.eskimo.com/~billb/wing/airfoil.html (http://www.eskimo.com/~billb/wing/airfoil.html)
Edwin

Anwar ,
I think threads like this , the prop one , 2.4 G one , and similar threads  should be grouped separately under  a classification like  RC Equipment   information  data base or something like that
sai

Done. Created a new "RC General Topics" board, to host threads that do not really fit in the other boards, or threads that seem to fit into multiple other boards.

Note that we want this board to have items that are long lasting RC informational value.

Aerofoils are a pretty technical topic that gets heady after going a just a little deep. For example why do we have flat bottomed (Clark -Y), semi-symmetrical, symmetrical and under-cambered aerofoils.

If bernoulli's principle explains lift of a "common" flat bottomed aerofoil how do we explain inverted flight of an aircraft.

For flat foamies the thrust is the element thats pulling the plane. IN 3D, the wings don't give lift - aerofoil or not.

Coanda effect is a significant player in generating lift. There is plenty of literature on this, here are a couple.

http://www.discoverhover.org/infoinstructors/guide8.htm
http://www.newfluidtechnology.com.au/THE_COANDA_EFFECT_AND_LIFT.pdf

Does this mean that a plan that has a semi symmetrical or flat bottom aerofoil will not have 3D capability?

3D capability is pretty much about thrust (not really "lift from wings").

hmm... All the 3D models that we see have vary large controls (elevator, rudder and ailerons). So if a model has these huge controls and has a power more than 1.5 times the weight, then it should be 3D capable. Right?