RC India

Respected Modellers,
we all have made different models and yet many models are to be made from the forum members and rc lovers.
For beginners its always a big challenge to make such plane , that are for of forgiving nature. but most important is that it GLIDE well.

so i request all modellers and Seniors to give all their knowledge and Skills , to make a perfect plane or Glider plane like Apprentice or floater or parkzone Radiun.

In short, what it makes or need to make a perfect  Glider or pane that glides well .

Your all ideas and knowledge will definitely help others and Beginners.

Thanks

One should try to do following things to get a good glide
1. Key to glide is keep weight less, aspect ratio high, lower drag and higher lift.
2. Try to use airfoil shape wing. Select airfoill which has low camber(wing should not be thick) and high cL/cD ratio. Some good airfoilf for this are SD7037, S4233, hq3512 etc.
3. Don't use bulky fuselage. Try to use thin fuselage with smooth body
4. Reduce as much drag as possible. So try to keep all surfaces smooth.
5. Keep proper thrust line. Use slight 1-3 degree down angle while mounting motor.
6. Use winglets at the tip of wing to reduce induced drag.

Thanks Nikhil, :)

please elaborate the things  8-) ( how to obtain those )

for eg. how to attain , aspect ratio high, lower drag and higher lift.  high cL/cD ratio.
 
how to  Keep proper thrust line.

A crude design for a simple glider could be as follows.
Considering weight of plane to be 600gm, set aspect ratio around 8-10. So set a wingspan of 1500mm and chord of 15cm. This will give wing loading of around of 2.66kg/m2 which is good for a slow flyer plane.
in order to reduce drag, try to put parts like battery, receiver inside fuselage and not hanging outside. Make fuselage streamlined and smooth.
High cl/cd ratio is property of airfoil so select airfoil accordingly as mentioned in above post.
Thrust line passed through shaft of your motor. Mount motor in such a way that it makes 1-3 degree of angle with chord line.

And most importantly put your CG around 1/4 of the chord from leading edge of wing and you are ready to go.

thanks a lot nikhil , want other senior members to discuss and place their views also.

i have made a wing of 66" span with aspect ratio of 13.2 and trying hard to bring down weight to 400 gm. how well will it  glide

Hello friends......

Well.... If I can add my two bits to the conversation.... maybe I am of too old a school of aeromodelling and not too much into what the younger generation can do or plans to do....  My idea of aeromodelling is Keep It Simple.....

OK..... I have mostly flown gliders and had made them with Balsa wood..... Never used foam of any kind in them.  BUT now I am doing one a 5 ft glider called Guppy with HD Foam wings (Blue Foam) but will still need hard wood spars to run along the length.  I have always found working with balsa easier when making wings as the wings come out much stiffer and the generally do not bend in the air.... that's a personal thing.  Though now I am trying to make stiffer wings with normal thermocol... leave aside the HD thermocol.

Now the real issue....

1.  Balsa constructions are extremely light and rigid.  They can be covered by anything right from kite paper to normal gift wrapping sheet to vinyl sheet to monokote.  The kite paper with dope on it is the lightest and probably the easiest.  The next is normal gift wrapping sheet.... it is extremely light and need not be painted.... just buy the sheet of your choice of colour and use it to cover the model.....Well.... monokote is quite expensive and vinyl sheet is HEAVY.

2.  You may try one of the two models which I am putting up here.  The drawings can be taken to any poster printer and enlarged to the size you wish.  I will recommend you make a 5 feet glider first.  

3.  Aerofoil.... well... if it is your first model... GO BY THE TRUSTY "CLARY Y"  aerofoil..... its the easiest to make and works well enough... other fancy aerofoil will make your life miserable if you want to get the calculations or the shape correct.  After the first Clark Y wing your make experiment with SD7037 aerofoil....  Be sure to keep it about 15-18% thick.... this is how you will be able to give good strength.  If you are keeping it about 15% thick then make sure to add a 2mm sheet covering for the area from the LE to the main spar... like a D Spar for good strength.  In any case at least cover the top of the wing from the LE to the main spar for strength.  OK if you wish to got he foam way... make sure to add a vertical spar (of nearly the same thickness of the wing) along the two top and bottom spar along the length of the center sections to have the required strength.   I even today prefer the Clary Y and so you too may go by that.  Incidentaly Sharma's most successful glider model Orange Box uses a Clary Y aerofoil.  The kit costs some Rs 2,500/- if I am not wrong.

4.  If you are making the guppy, the fuselage might be a bit difficult to make as the original design has a molded fuselage.  SO make a fuselage of something like the one in the other design i.e. Dancer.

5.  DO not go crazy reducing the weight of the model.... first make the model as it comes using parts which are known for their light weight.... Like Balsa wood.... when using foam be carefull not to use a heavy covering like the venyl sheet.  Onec you have made your first model..... you can thereafter decide how and where to reduce weight.

6.  To reduce drag just ensure that the overall surface is smooth and not rough.... You may use Dope on the Balsa wood fuselage, Tail fin and the Tail plane to make it smooth and shiny (at very little cost to the weight penalty).  The wing as it is will be covered by a smooth covering.... which is stretched real tight.

7.   You may keep the thrust line about 1 degree down from the datum.... may or may not give right thrust.  You may have an angle of incidence of 1 degree or so between the Wings and the Tailplane.

8.  Winglets... forget it..... KEEP IT SIMPLE..... leave this topic.... you are not making a competition glider that you need to worry about it....  Not that they do not have their problems.....  

9.  Keep the CG somewhere near the 1/4 to 1/3 way down the cord length from the LE.

10.  Keep it a three channel one initially.... as adding ailerons for the first glider will cause problems of lack of rigidity for the wings.  One needs to be careful while adding ailerons otherwise wing twist can occur giving undesirable results.

11.  Lastly..... go on the net and look for aerodynamics chapters on Aerofoils, Lift, Drag, Lift Augmentation, Balancing for level flight and Gliding at least.  It will be of great help.

12.  Here are the two plans.....

This is just my experience of many decades of aeromodelling and experiences of flying.....  You may choose to take it verbatim or as you like.


Happy Flying.

sir i face problems on profiling and deciding rib dimensions for the wing. My quest is how much should be the camber of a glider aerofoil. Some people say to make it thin whereas dimensions rule out the same statement. If i got to go by dimensions which states max camber shud be 15% of wing span at 30% of cord length from leading edge. if its a tapered wing then max camber varies due to varying cord length. so what shud i do

Well... if you are making a Clark Y aerofoil.... keep it around 15% at max thickness at all chord along the wing. IF you are going for any fancy ones.... you may like to go up to 15 - 18% thickness.  Though it is right that  athinner wing gives low drag.... but the payouts of low drag have to be weighed against the lift and the strength required from the wing.  Whenever a wing produces lift there will be drag and in case of an over thick wing the air flow separation may take a bit early...... but that may be after 20% thickness.  So be sure that a 15 - 18% thick wing is absolutely fine.

@manojswizera
To get a feel of gliders, you could make this 32" free flight Mercury Gnome by Ron Young. One of our first successful models pre 1970!
http://www.outerzone.co.uk/plan_details.asp?ID=4478 (http://www.outerzone.co.uk/plan_details.asp?ID=4478)

Or you could get an Apple Box kit from Sharma Models of Jodhpur (similar to the once famous Orange Box from Aurora / India Hobby Centre)

If you feel more ambitious, you can take a look at this
http://www.rcindia.org/kites-trains-free-flight-and-all-others/sweepstakes-rctlg-k-k-iyer/ (http://www.rcindia.org/kites-trains-free-flight-and-all-others/sweepstakes-rctlg-k-k-iyer/)

Remember that a GLIDER MEANS NO ENGINE
(You were probably thinking of a POWERED glider, right?)

It just occurred to me that we have all misunderstood your question.

"How to make a plane glide?"

The correct and short answer to that is
"CUT THE POWER

Doubt if that was helpful  ;D

 :rofl: :rofl: :rofl:

Nice one

KK sir dont take the trouble of explaining to manoj sir, he asked the question 2 years back.

I think by now he would have mastered gliding an rc plane.

Thanks KK sir, that was a great information and especially the links, i always ready to learn from you.
Your rctlg is a masterpeice, but i have zero experience in those.

RCNeil21   I am still a Beginner  ;)

@ shobhit:
am using this online tool "http://airfoiltools.com/plotter/index". As u said to keep the max thickness 15% for a clark y airfoil; i did it and resulting airfoil is too thin. kindly have a look. 75% thickness seems to be fine enuf. Kindly hav a luk into it guys

and yeah one more quest; do we need to keep uniform thickness of all ribs along the wing span or we can reduce the thickness.

Dear Abhishek..... well thickness of the aerofoil in aerodynamics terms is actually thickness by chord ratio.  A 15% thick chord means that the thickness of the chord measured at the maximum displacement point of the upper and the lower camber from the mean camber line.  This max thickness may be around 30% of the chord from the LE (may be depending on the type of aerofoil).

75% thick aerofoil would be too FAT.

Yes you can change the camber from the root to the tip.... This means that the aerofoil at the root need not be the same as that of the tip.  This also means that the thickness of the aerofoil need not be same from the root to the tip.  BUT... mind you it MUST be same for both the sides of the wings.

Happy Flying

thank u sir

@abhishekdas11
Didn't notice that you had posted in Manoj's old thread.
Reply no 9 was intended for you but manoj replied anyway ;D
Perhaps you may like to see reply no 9

i had been thru all replies....i said u beforehand as m into maintenence and new to rc so its way far for me to sit think and make plans to design an rc...
thank u anyways Mr Iyer

Mr. Shobhit17,
                   I read your post, it is awesome and really informative but the picture of DANCER.JPG is not so clear. It is unable to read. can you upload a good new one along with it's all the orthographic views please.

Dear Ashwini,
I realised that this site does not allow a full picture to be posted and as a rule scales down the quality of image.  If you give me the mailing id and I will send it to you.
regards

sure, it is- shukla.ashwini06@gmail.com
thanks