RC India

Here are the pictures of my first plane being built by sunboard. I have just compleated with the skeleton work of the wing.. I am posting pictures of the wing..

These sheets have density 450-500 kg/m cube which is nearly two-three times that of balsa wood.. I am using these sheets, the reason being, balsa sheets cost approx INR 150-160 for 4"*3' for 2mm. 
Sunboard sheets cost Rs. 60 for 2'*2' sheets(2mm)which weigh 340 grams.
 
The reason for using is  :
1:Its stiffer than balsa(2mm),
2:Easily workable, and forms very strong and quick bond with with each other using pvc adhesives like feviquick, ad flex quick bond, and all-bond.
3:And off course, the price factor. ;D

Wing size 40' functonal, and 44' edge to edge.
The weight of the assembly is 96 gm and is equally stiffer as a more dense balsa wood construction.
The wood used for supporting is Mirandi wood(which is easily available here in lucknow),which i have cut from a long board, .

I have however tried my best to reduce its weight bu cutting off the extra sunpack and forming trusses, but i want your comments and suggestions which may further help me..
I also want suggestions on which material should i use to cover it :headscratch:(however i have decided to use OHP sheets), i dont want to use monokoat, as it costs too much..
I also want to know how much balsa wood construction weigh for the same..
?

i will post the pictures of fuselage soon when it gets completed..

A few more pics,
myself working very desperately ;D
 for weight reduction.. >:D

Nice building. What is sunboard?

Nice building

your wing will have almost no torsional strength.

The spars are too thin . the ribs too far apart.

basically it will warp very easily when covering.

Sunboard is the brand name for PVC foam board.. Usually used in advertising displays and cutouts with banners glued onto them.. Its quite a soft material..

The spars are thin i agree, but what i found that a mirandi wood spar of around 4mm dia is equally or more stronger than 12 mm dia of balsa wood one, and its even heavier than it. though i have not weighed.

thanks for reminding about tortional srength. so what i have decided,To increase the tortional strength, i will provide a further reinforcement in the top portion of the ribs, hence it will have reinforcement at all its peak edges, thus reinforcement bars forming a triangle in its crosssection..

Sir please help me to compare its weight, wrt balsa..

lots of hard work!!!!! i hope u wil reinforce it wi CF!!!

 :headscratch: :headscratch: :headscratch: :headscratch:
I dont know how this topic has been moved to electric planes. >:(. I am making it for ASP .25 engine. Which i have ordered from RC Dhamaka.

what is this new stuff Sunboard ???? I am already confused  ???  :headscratch: is this sunpack/coro  ;D???

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Yes you are absolutely right.. Its sunpack
Both are commercial names.

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It doesn't look like coro to me. I can't see any flutes or ribs anywhere.

No, it doesnt have ribs or flutes. Its totally solid.

This material is not coro or sunpack. It is sunboard(no flutes). I have also seen it in kolkata in signage and printing shops. It is basically foam sheet(like biofoam) covered on both sides by pvc layers; available in different sizes and thicknesses. I was planning to build my first plane out of this but later i found biofoam in kolkata and decided to go with it. Biofoam has the advantage that it is much much lighter than sunboard, otherwise sunboard is absolutely suitable for RC modelling, much stiffer than biofoam. It is just that the weight factor is too much that it can't be neglected unless you don't find biofoam in your city.

This material has already been used by a fellow member for building his plane. I can't find the thread though. But im pretty sure that this was used.

ya i used it , the drawback is that your plane will break straight away if you crashed(as i did first time) ..........this material is not suitable for building (crash proof) plane.

good effort and clean finish,Abhay. Just that choice of material could have been better. However, Sunboard is a good replacement for plywood ! You can use for your motor mount, skids, dihedral braces etc.,

Nothing wrong with using it as ribs as you have done, as long as you provide sufficient reinforcement.

As a boy, I have even used dried trunks of Drumstick Tree (the vegetable) - this is very light wood, and if you dry the log right so as to avoid rotting, you'd get ivory like blocks - excellent for static models, nose blocks, wing tips etc., But cutting into sheets is a challenge.

Try it !

I have also tried drumstick, when i used to make gliders, but they are very weak. i have never tried to cut it into sheets, but what i found that its very light, lighter than balsa i think, but much weaker. Its strength is equivalent to compressed thermocol, but it doesnt have any elasticity, and breaks at little hard knocking. I guess compressed thermocol is better than drumstick, as its quiet elastic.

abhay - do us a favour pls - tell us the wt per unit area
or density of sunboard - you can do this by measuring
the weight of a piece and then back calculating - then we -
who have not seen sunboard can compare with balsa/coro/thermocol/biopak

Dear Mr Saikat,
                    Please read my first post of this topic. u will get all the details.

Yes - sorry - did not read it carefully enough.

Going by your figures - it will not be a good model building material
as its strenght to weight is very poor. you will be better off building
with biopak.

don't let this put you off however - build and fly by all means - we
all will  learn from your experiences.

 :thumbsup:
finally the wing is compleated..2 days back, but was unable to post pics due to academics pressure.

Let me go step by step:

After the reinforcement, The nose was made using 0.5mm thick paper sheet which is called Ivory sheet.

Making smooth curve was a typical job, which was done successfully by making half cuts..

Finally the nose was made

The next callenge was covering...

I used a transcluscent plastic sheet( used for covering draughting boards) , instead of monokote, which is nearly 5 times in cost, and equal in strength.

Loss of knowledge, made me stick the sheet directly to the ribs,using adhesive, which was found to be fruitful in gaining further strength, but finally lead to few wrinkles, when the wings were exposed to hot air to get further tension in covering membrane.. As can be seen in pics

Even though, the excitement lead me and my accompanying friend to go on bike at 2 o clock in night on road, to check the lift,  in the chilling cold of winter in central india........And..further  :giggle: :giggle: we didnt knew the procedure.

We were just trying to get an environment of wind tunnel ;D

Further, the wing fell many times on road at speed of 40 km/h on road, without showing any signs of breakage other than the truss of one side which had two crack developed in. may be because it hit the divider once.
Now i need to cover the sides only...
Please suggest materials

great effort and innovation.
Real value for money builder and i like your way of thinking out of the box.
The material for the ribs is called FOAM BOARD. It is the white background material onto which vinyl signs are stick to. comes in thicknesses from 2mm to 6mm. I have used the 5 mm one to build part of my field kit.
Has the strength and wieght of ply wood of the same thickness.
good handling properties. Sticks well with cyano. Easy to cut with a hobby knife.
I don't know how well it will be resistant to fuels. May be safer to use on an electric set up.
Or soak a bit of it in fuel for 2-3 hours and see how it behaves. The best time to think of how you plan to power the plane will be before you build the fuselage.

What is the chord and span of your wing? the length breadth and max thickness.? Also what is the weight?
all the best.
As far as covering the wings go, use the thickest quality plastic gift wrapping paper available at you neighbourhood stationary store.Buy the stuff that comes in long rolls and not single sheets. Cost Rs. 10 for 100cm x 90cm sizes.
Stick it with rubber based glue- FEVIBOND not CA. The wrinkles will disappear if you warm the covering with  a hair dryer/ electric iron at low heat.
regards.
Avijit

is it a good material to build rc boats with??? ???

yes should be good for Rc boats. as it is water proof

nice build man...nice choosing of materials  :salute:

 :thumbsup: :thumbsup:

Thanks Avijit,
                 I like the appretiations and suggestions from you all guys..

Regarding the fusalage, i will be making it with Plywood and thin sticks (4*4 mm approx in section) of mirandi wood., Since i have decided to use .25 size engine(ASP), which has been dispatched from RC dhamaka, nd im jst waiting very eagerly for it to reach me (:|~

The chord length is: 220 mm
max thickness is 38mm which is at 65 mm from the edge of nose.
Wing Span is 40 inches.

Weight not yet calculated, but expect it to be below 200 gms. I will pst it soon.

 :help:Please can you tell me the dimensions of 240cc of fuel tank(by RC dhamaka), so that i may proceed with the fusalage.
i will make the fusalage accordingly.
Thanks,
AbhaY

Basically, I was trying to move threads to the right boards, out of the "College projects" one.  That one is for somewhat exotic stuff. Plan builds do not really belong in there.

I have moved this to Glow planes board. 

BTW, great build :thumbsup:  I don't remember seeing the use of regular plastic sheets for covering so far here !
 

Thanks anvar. :)

Hello buddies, ;D

Ive started with the fusalage as well.

The whole framestructure is been built using mirandi wood,, and 6mm plywood. Though incomplete, i expect to work on it ,to build it complete on the coming saturday.

 {:)} and one more thing discovered, mirandi wood, if completely dried, shows properties similar to bamboo wood, in terms of flexiblity and strength.

Your suggestions will further help me...
thanks

bump :violent: ??? ???

dont know what to do further to maintain cg of plane. weight of engine itself is around 500 gm including the tank.. help buddies

Fusalage compleated.
Only airlons left.

Good build.

Take care of these,  points (To ponder)

1. take off speed will be high considering the weight of the model and the span, so run her on the take off path controlling direction before you apply backward pressure on the elevator control.

2. will be slightly snappy in the roll plane, carefully balance your laterals.

3. Do a level flight stall(Called the 1 g stall) before coming into land, can wing drop, looking at he taper of the tip chord.

4. Don't be surprised if it takes a a while to lift off.

:thumbsup: looking forward to the video/outcome.

PS
is it possible to maiden electric?,
very neat nose and the tail-wheel combo, i remember a real life aircraft had one such design

augustinev sir,
i would like to know more about 1 g stall. I m very new to Remote controlled plane. And this will be my first engined plane. I only have experience with self made electric gliders(non r.c) and r.c. micro planes( chinese ones).

As far as model is considered, it is a mixture of many airplane images from google, and the balsa built-ups of this forum. the tail wheel is just to protect my rudder during first landing, instead of tail skid.

Please instruct.
My present AUW is 1.125 kg, excluding only aileron and its servo.Weight includes batt, Rx and half filled fueltank.
I would also like to know whether 9 gm servo is sufficint for aileron.though i dont think so, but ill go for a standard servo only on experts advice.

Abhay,

1. 1 g stall is in level flight reduce the speed and notice the speed at which her nose/wing drops. this you must do it at height, this speed you must not reach on landing, since this speed is going to more of a perception, you need to remember (a) model flying higher, speed appears less (b) winds are stronger, higher cater for that (d) on approach keep speed slightly higher, the way to do that is look at the nose wheel, it should be slightly up remember to hold it at a certain attitude and not change it, use power if required
(e) if you are new to the game, get some expert to maiden

2. As I see it, wing loading of your model appears to be high, cater for that

3. If your proving your airframe's airworthiness i suggest you save your engine, try it with motors, motors definitely withstands crashes better,

4. be very very critical on your CG, a shade forward is better than back, remember that.

all the best. :thumbsup:

post some more data, let me run some math for you.

don't worry, it will be successful maiden (see if you can reduce profile(Form) drag)

ps

9 gram servo, if you have used jitters quite a bit, especially when there is unnecessary loads like the control resistance, go with 16 gms servo should do just fine, lateral control throw should not be too much remember, because snappy in roll will respond in roll input also faster,

augusteniv sir,
what all data is required for calculations? please tell me. i dont know what all things to provide and how to calculate them. please specify.

Regarding drag, please suggest me some measures to reduce it.

Is there any way to reduce wing loading further? Or shall i construct a new wing with larger wingspan, since i dont want to lose engine, due to high speed.

data:

1:CG of my plane lies beneath the wings, at nearly 30% of the chord length.(the tail is slightly raised up)
2:The rear wheel of the three in front, is at nearly mid of chord.
3:Wing span is 40"(effective).
4:The fusalage has not yet been covered,(whether covering will reduce air friction, reducing drag?).
5:tail control servos are at tail to balance the ASP .25 at nose.
6:AIRFOIL section is semi,symmetrical.
7:Chord length  is 220mm( 8.66")
8:Wing area=346.5 sq inches.

the attachment contains the reference which i have refferred all throughout.

And sir, what must be the estimated speed of takeoff?

Model flown. :)
today i took my model for flight. It flew at very high speeds, so i didnt used rudder at all, just saw the liftoff and landed, all done in a slight curve or nearly straight line.
Even airlons doesnt have any effect.
Im not happy with the flight so i decided to increase the wingspan.
Im am a slight dissapointed, please help people..

/i was just wondering whether to reply or not, but edison uncle striked in my mind.

increasing wingspan was not possible with the previous wing so i made a new one using reinforced thermocol..

Now it was a flat bottom airfoil for more lift at slow speeds..

now wingspan is 50 inches