RC India

hi friends this is akshay...i am making a flat wing glider out of biofoam for my school science fest....i am using a DC motor the one which is found in dragonfly helicopter and i had a 2 channel radio.. and receiver.....  but one channel is not working  in the receiver so connnected the working channel to a relay so motor takes direct power from two cell lipo 1800 mah and the receiver uses 7.4 volt lithium ion battery 800 mah............using a 6 inch prop ....wanted to ask ...will it fly or not as i am getting a good amount of thrust....wanted some helppp ...before building the wings....please help me......can this type of a thing fly or not

Wahhhh! Somebody Trying 'Free Flight Model' in the R/C era of today!

Well Akki, speaking of 'Flat' wing, my NCC instructor would have beaten me to death if I had press not to Sand balsa for aerofoil shape.. but it was back then in early 90s, and hardly many people used Electric motors in planes.

The Answer is YES for both. But a 1800 mAh Lipo would need at least a 30" wingspan plane. You would have no control on the plan except climb/descend   so setting both the CG axis right would be ultra critical.

Se what you can salvage from the old plane/Heli you have.

there is no controll of mine over it...that one channel is used for  switching on and off the motor and its a school project which has to be submitted for the science exhibition

A flying wing is very difficult to control. It would be better to add some vertical fin as a yaw damper. In the models that i tried making i found them to exhibit dutch roll tendencies. My advice to you would be to add control surface for controling pitch,yaw and roll. And then just trim them so that your plane takes the desired flying path.

Regards

I don't think he is building a flying wing. Looks like a regular plane with profile (flat) wings.

My whole perception about flying wings being difficult to control changed after I flew the "Mini Slinger". I am sure a bigger sized wing would be even more stable.

I do agree, by flat wing he means the profile planes.

But akki, its not very hard to give a under chambered Aerofoil to your flat wing of the glider. the Wing loading (the capacity to lift weight) of the wing would increase as well.

Search for 'Blue Baby" and see how people have 'Heat Formed' Depron wings to aerofoil shape.

Oh...my bad.


Anwar i was talking in general...designing a flying wing is so much tougher that designing a conventional plane. At 31 inches the mini slinger may be easy to fly (i havent flown it)...but as you go down in size , it becomes really tough to design the flying wing. I have atleast made hundreds of prototypes for the iit competion ( under 10 cm flying wings) but still havent been able to figure out the right design. My mini mini slinger is oscilating on roll axis (dutch roll). My first prototype how ever was a conventional plane...a cake walk as compared to a flying wing but not enough flying surface. So i speak from my experience. I just hope i make it in time for the competition on Sunday.

This is what i have come up with till now.


Regards

I was talking about my own experience, where I was cautioned about them being unstable when I initially brought the subject up (I think it was Sai who mentioned that they *tend* to be unstable).  But when I got the Mini Slinger, it was about as stable as most of the other stable foamies and some of the bigger planes I had flown. 

But at the size that you are trying to build them, I can't see how they can be stable !  The ones used commonly are typically bigger, and hence are more stable.

I think you should make the wings extend more towards both sides, even at the expense of some width, and may be try some dihedral :headscratch:

some people have a misconception about my design....its normal plane with V tail but the ...main problem is that the biofoam is only 3mm thick..its very difficult to give it the shape of an aero foil... i post  some images as soon as possible...the body is some what like this

does anyone know that from where i can get a small but power full brushed dc motor

Well Anwar..that is the challange  :giggle:

The plane has to fit in a box of 10x10x10 cm. This is just a prototype..once i get a stable flying platform...i will add maybe dihedral or wingtips later. Or may be add a second wing above it. It is such a learning experience building this model. :giggle:.


Keep a rolling pin ready by your side. Boil water (in a container as big as possible) till it starts bubbling....wear gloves to protect your hands..dip the depron in the boiling water for 3 secs....take it out and immidiately start rolling it with the pin till the depron cools...and then you have a curved top airfoil surface. Glue a flat plate at bottom and you get a flat bottom airfoil. First try with smaller depron pieces till you master the process.

Regards

mr ankur use ur brains ....the box has nothing to do with the plane :banghead: :banghead:   its just that i have kept the body on it

and its not depron its biofoam which is laminated from one side

Mr akky

First of of all show some (language) decency on this forum towards the people who are trying to help you.


I think it is you who needs to use some brains and GOOGLE...depron and biofoam are same...depron is known in India as BIOFOAM. And you had never mentioned the word "Laminated" before.



My post is just about getting a flat bottom airfoil shape from a 3mm depron sheet using heat forming. Please read the posts before replying randomly.

Regards
Ankur Kaul

A Science Festival that to in a school level emphasizes more on the concept than the working of the model. So here I won’t discourage you about your present effort, but to try something simpler like hanging an aeromodel by wire/ nylon thread from the ceiling to appropriate distance and explain the basic controls of aeroplane and aerodynamics would be a better presentation without much risk. You can use your 2 ch r/c, motor from Dragon fly, battery what ever you want because weight of the aeromodel will not be a constrain to you.

a big and sincere apologies mr ankur...sorry for my reply...and thanks for tellin

Akki - You have to realize that any online forum best acts as a source for ideas, guidelines, suggestions, best practices etc, and NOT a one-stop shop for PERFECT solutions. 

We understand your enthusiasm, and would like to wholeheartedly support you (and everyone else who are here to share and learn from one another). But you have to keep the above point in your mind at all times, and take it slow and steady :)

Some aspects of any RC project/task will involve trail-and-error, or iterative progress.  Everyone who has taken time to respond to you here are earnest in their intention to help you, and I believe you have acknowledged the same with your above post. 

What you are trying to achieve would be pretty difficult with just two channels.  I mean to make a fully controllable plane with just 2 channels is a significant challenge, unless you compromise, for example by making the throttle constant (and make the plane use up available battery before landing.  But using a lipo, over discharging it has its own issues.

For a school project, would Mr Maharana's suggestion be enough ?  Of course it is not as "impressive" as an untethered model, but is simple to implement.

sir i cant hang the plane with a string under the sky..its impossible..... :help: and out of two channels only one works on the receiver so using it  for controlling the relay switch which gives direct power to motor from the lipo..receiver is powered by lithium ion.....as the motor is a brushed dc

One channel is working out of two, that is why I adviced you for a hang model.

i cant hang it we have to dispaly the model in our college field

Is biofoam/sunpack really depron ?  It is a substitute being used in India, as real depron is not available, right ?  At least that was what I had gathered from earlier discussions.

Biofoam/sunpack is much more brittle and hard, guessing by similar material available in all local library supplies (stationary) shops here.

sunpack is brand name for corro

My doubt still remains. Real depron and biofoam are different, right ?

yesss sir they are different ....the one which i use is 3mm ...laminated from one side....orignal depron is much better

Hi Anwar

Depron B.V. is a company in the Netherlands that originally developed Depron foam decades ago. The name Depron is just a "trade name". Technically it is extruded polystyrene which can have either an open cell structure (EPS) or a closed cell structure (XPS). The ones we talk about are the closed cell structures.

Depron is produced by continuous extrusion of polystyrene under controlled extrusion pressure and extrusion temperature. This process permits accurate control of thermal and mechanical properties by varying the pressure and temperature.

If you check out the biopack website..they too mention biofoam to be extruded polystyrene. So in my opinion they both are same...the only difference being that depron may be produced at some different manufacturing process parameters resulting in high quality.

But then you can say they are different too as they may have different properties.  :giggle:

Regards

I see.  To the average "Kumar ;)" it is all about the characteristics and performance.  Since the structure itself is different and their behaviors are also different, it is fairly safe to say they are different !

dude why not give a try :thumbsup:

So whats the progress so far? has this thing been glide tested? I used to have a big thermocol model (rubber band powered) which had a super simple wing.. Basically the wing was a sheet of thermocol with the leading and trailing edge cut at an angle giving it a basic airfoil.. It flew quite well.. The airfoil was something like this..