RC India

I want a airfoil design for a trainer. Can some one give a airfoil template so that i can just print & cut it out.

I have used PROFILI, a free download air foil program. it is good but limited functionality.

http://www.aerodesign.de/

Sandeep

Thanks sandeep.
I am begginer so can you tell me the relation between chord length & wing span. Is there is one :)?

Suggest you do a search on Clark Y.....you may also want to do some basic reading on airfoils.

good luck!

Like Anwar bhai always suggests, search the same here first.  ;)
http://www.rcindia.org/electric-planes/wing-span-and-fuse-length/

Regards,
Dileep

 since I am online, thought I'd just add a few points for Sandeep to elaborate later on.

 In simple terms, the relation between span and chord  is known as aspect ratio.

 Typically, a trainer's chord is 1/6th of its span. For example, a trainer with span of 36 in should have a chord of 6 in. However, if you wish to make a glider with a wing of the same span, then the chord should be 1/9th of the span, or 4in.

 Thickness of the airfoil is also important depending on the application.

 However, for the time being lets consider the following Example that you can follow if you wish:

1. Span - 48 in.
2. Chord - 48/6=8 in
3. Thickness of the airfoil - 8 to 12 % of the chord
     
    This means, the thickest point of the airfoil* should measure anywhere between 8 to 12% of the chord. So for a chord of 8 in, the thickness could vary between 1 to .66 in ( or 2.54cm to 1.67cm). I'd recommend 1 in at least.

 * The location of the thickest point of the airfoil is usually 1/3 the distance from the leading edge of the wing. In this example, that would be 2.66 in from the LE.

** The range of the thickness can vary beyond 8-12%. A thicker airfoil is slower, creates more lift and hence most suited for trainers.

 You can also go to http://www.ae.illinois.edu/m-selig/ads/coord_database.html 
and click any of the alphabets - this would open up a series of airfoils.

 But there's a lot you can read on the net.... :thumbsup:



   

Nice to see more people coming for help.  ;D

chord is the distance between leading edge & trailing edge.
Wing span is distance between two wing tips.

Awesome explaination  {:)} {:)} {:)} :bow: :bow: :bow:

thanks bmblb.

Like wise is there a dimension for

1. The vertical & horizontal stabilizer which should be there for a particular airfoil (chord length, wing span & thickness of airfoil).

2. Fuselage length from the wing to the point where it has vertical & horizontal stabilizer?

U can find an article as how to design ur own spad in spadworld.net forum..In tat each n every relationship is explained..

I got a software from this link
http://www.grc.nasa.gov/WWW/k-12/FoilSim/index.html

I am planning to build a pusher

wing span - 100cm
chord length -100/7.6=> 13cm

I made the chord length so that the plane has good gliding capability.
I am using clark-Y design as bmblb suggested.

Is this ok?

Clark y design

As regards the length of the fuse, I follow this:

Wing Span/Fuselage=1.8

Fuselage=wingspan/1.8 (For example, for a wingspan of 48in, the fuselage can be anywhere from 27 to 33 in.
The Distance between the TE of the wing to the LE of the horizontal stab is the tricky one and can make considerable difference in the performance of your plane.

Start with this for the Fuse:

1. Nose to LE of Wing = 1 chord length
2. LE to TE of Wing = Chord length itself.
3. TE of Wing to LE of Hoz Stab = 1.5 to 2 times chord.

This is a crude way but will do. You may have some challenges with getting your CG at the right place.....but that is best experienced and you will eventually get it.

share pics of your plane as your progress....

i think simplex airfoil is a good place to start with  :)

azhaguvel, i agree with sahil, if your chord is going to be small, then you cant risk high cambered aerofoil, reason is,  cambered aerofoil has large CP (Centre of pressure, a point at which all lifting force is said to act) movement, problems are two fold (a) you need to balance CG perfectly(which means you have very little error margin on assessing length of the aircraft) at no stage CP can go ahead CG, you will loose control. (b) stall and recovery will be an issue, high elevator throw and frequent trimming will be required.

Bhavesh's Thumb rule is bang on, for a Clark Y ?, can be tricky.

Clark Y ? think about it, for a 1M aircraft it is little too cambered.

all the best :thumbsup:

PS
I had a little hand in the NASA Foilsim, way back in 1999, if you can crack the java class file, should find my name there in one of the comments, i guess.

A pic of any recommended airfoil would be a great help :)

I am not generalizing, however most scratch builders start with Kline Fogleman first, it was a sensation in 1974, easy build, no movement of CP. very forgiving in design inadequacies and inaccuracies, attaching image. choose your pick. if KFm appeals to you, i can send you some reading material as well (Indicate whether you need tech or non tech stuff) :thumbsup:

http://www.rcgroups.com/forums/showthread.php?t=369658

try the above link, there is a program that will generate simplex airfoil will try to post a direct link

sahil

try these programs  :)

 http://www.hippocketaeronautics.com/hpa_plans/categories.php?cat_id=59&sessionid=4688e71830344dbc5a6007c111ed0320

Thanks sahil & augustinev will check out your informations

sir

i think this might help.....

http://adamone.rchomepage.com/cg_calc.htm

 :headscratch:

http://adamone.rchomepage.com/index5.htm

Hi Guys
 a simple Question
 How to make a airfoil on a thermocol without using a hot wire foam cutter.

first thing is, can a thermocol be used for a wing? its very fragile & will break right?

Yes.

Azhaguvel,

Balsa is also fragile and will break if crashed. The question is how much reinforcement is needed to produce a structure that is light and strong.
I have been using biofoam sheets for building and no issues so far ( apart from crashes). I have used biofoam for AUW of about 1.2 Kgs

u can use sand paper to get tat air foil shape.

thanks.

i don't have knowledge about bio-foam, haven't even seen one :P.
But thermocol means the normal ones we find in shop, can that one also be used?

No, i don't think that will be strong enough. However, if you find high density thermocol, that would work.

Normal thermocol is too soft so it will need more reinforcement to make it rigid for wings, but yes it can be used

I m using high density thermocol

Hi Guys,
 Can I fly my airplane without a airfoil ? Please tell me.

yes, ofcourse you can. But having a airfoil improves the stability and performance.

Thanks a lot Azhaguvel.

Yes you can use thermocol for making wings its quite economical and light. Paper the thermocol to get the profile u require and add a spar at 1/3 from the LE to prevent flexing of wings.

another simple way is to use coro for wing it is very strong & also light weight