Hey everyone,
I have a thought : that we all get together and design an RC Aircraft! Now we are doing it separately...why not we "all" get involved...each one having its own expertise....its own plus points!! The end result would be fantastic!
This plane would be "by RCindia - for RCindia" !!
This Topic could also help others by becoming a role model by itself.
Others could get help/information directly at one place!
I am very excited about this plan.....lets make it happen.
Need others opinion too....
Cheers!
Vikalp Luthra.

It can be a simple design, but the point is to cover all of the major aspects required to designing an aircraft....like aerodynamics, performance, power, stability and control, structures, etc.
Lets follow a step by step aircraft design process and get a feel of designing a complete aircraft.....which is our ultimate endevour !!

Vikalp at first of all a million salute for you , for this great idea.. and sure, it may start from here.. keep ratio as 5:3:1.5:1... means.. if wingspan is 50 inches, fuse length is 30 inches at least, and 15 inches for tail plane and 10 inches for rudder.. is rough ratio as you can see many successful aircrafts are in this ratio.. and i am too happy to share any aquired knoqledge from my side for this.. even my life.. this also was my dream.. make it from fluted plastic board..( CORO) in to 2 mm.. will fly like a dream with some trimmings.. any one can make and fly.. EASYFLY RCI.. because we all are RC INDIANS.. 

yup!!! nice effort vikalp would be great... !!!!

gr8 roopesh!! Thanks for that superb information!! lets do it!!!
ok, now lets decide what kind of aircraft shall we all design......i think we should stick with basic designs.....a trainer may....what do you say?? & others too....

thanks pradeep! lets put each ones effort in it & make a gr8 plane!

sorry roopesh, i dont know what material is a CORO....would you explain it to me?

while keeping an eye on beginners.. a high wing trainer..  then a low winger.. in same platform..  

yes as said... an ideal trainer model has to have a wing span of 50-60 inches as this will help the trainee to gain knowledge of flying and ability to land in lil high pressure winds.. much drag produces more lift. and he/she could glide the model for some time and have a study flight... !!!

I would go for a 60inch wing with a 42-46 in fuse on the model... any inputs would help too!!!

sure.. the material co is a plastic sheet, is two thin sheets are toped with a drinking sraw like structure at middle.. just like a straw board.. this can be purchased in 6X4 and 8X4 sheets.. in various colour.., in some places this known as sunpack, and sunflex.. mostly this material is uded to make false ceilings and pavings in bath rooms and door panels..

i prefer 2 mm coro sheets to make excellent crafts with ease.. you can make an entire aircraft with a mere 200 Rs.. without painting.. and if you use balsa to reinforce the cost of the balsa will be addition.. and yes painting.. when you finished a craft with 50 inch wingspan, the dry weight will be around 700 to 750 grams.. and will be too stable with flight.. can make any type wings, any aerofoil.. any length with reinforcements..

once the design is confirmed, we can make a template from a thin 3mm metal seet for number of aircraft production.. can make various additions on it.. camera.. shooting guns.. parachute.. pilot ejections.. smoke.. and flower droping.. and lots..

Ok here goes the Design  Process:
Phases of Airplane Design:

1. Conceptual Design: Consists of set of requirements. Should have a concrete goal towards which we all are aiming. Here, with a somewhat fuzzy picture, the overall shape, size, weight and performance of the new design are determined. The product of the conceptual design phase is a layout of the airplane configuration.
Here's the vital Pivot Points of Conceptual Phase:
a. Requirements
b. Weight of the airplane-first estimate
c. Critical performance parameters : Cl max, L/D ratio, Wing Loading ratio (W/S) , Thrust To Weight ratio (T/W).
d. Configuration Layout-shape and size of the airplane on a drawing.
e. Better Weight Estimate
f. Performance analysis - does the design meet or exceed requirements? if no-go to step 3, if yes proceed
g. Optimization-is it the best design?
Above were the 7 intellectual pivot points for conceptual design phase.

2. Preliminary Design - in this phase, serious structural and control systems analysis and design take place. The design is experimentally tested. If successful, configuration is frozen and precisely defined. Drawings are made - i.e Lofting.

3. Detail Design - Consists of deciding the nuts and bolts that will go into the aircraft. In this phase craft simply needs to be fabricated. Precise design of each individual rib, spar and section of skin now takes place. Manufacturing process is defined. At the nd of this phase the aircraft is ready to be fabricated.

here is the example of cam carrying..

great consideration..

some more specs about the material named coro, or sunpack..
PVC Foam Board- Sunpak Board

PVC Foam boards is a chemically foamed, rigid, light weight extruded sheet with a fine & homogeneous closed cell structure. smooth matte surface finish on both sides.
Characteristics
* Light weight
* High strength
* Easily cleaned
* Easily fabricated
* Outstanding printability
* Uniform fine close cell structure
* Good resistance to light and weathering
* Low flammability
Applications
* Advertising signs, displays and hoardings
* Exhibition stands
* Interior design
* Point of purchase displays
* Walls and partitions

and if we Google, we can find lots of technical explanations about this material.. even include the chemical chain.. and can see lots of complicated descriptions.. about it.. but to us all this one is simple , cheapest model building material.. is coro sheet.. ver easy to work.. and inexpensive.. easy to paint and easy to form.. can also fix over balsa structure..  
for an example one link..
http://shgoldensign.en.made-in-china.com/product/WqnxLbYKgHVh/China-PVC-Forex-Sheet.html

Great idea Vikalp.......!!!

And nice considerations as roopesh sir said. I am definitely in.

At first we need to think about "Conceptual design". As we know the number of aeromodellers is increasing in India which means more and more beginners are coming in. So why don't we consider making a design that is better with the beginners point of view while having power loading and dynamics to easily allow advanced aerobatics. That way, everybody will wish to fly it. So, That should be our ultimate goal. Lets see what others say on it. Below are few pointers to help define the requirements and goals...

(requirement for beginners)
->Must be Less expensive.

->Must be simpler to build with available material. So we have to consider it making with Coro or Foam or both. Coro is stronger but difficult to work in comparison with foam. So it must be carefully decided which material is to be used primarily.

->It should be Hi-Winger.

->It should be pusher.

->To save motor and propeller from damage at the time of crash, We can mount it on somewhere middle of the fuselage like most of the trainers already sold.

->It should have typical 3 channel configuration(AET or RET) which can be further extended to AERT configuration as needed.

->It should have low wing loading.

->Thrust to weight ratio must be greater than 1:1.

->should support Hand launches as well as take Offs.

->Landing gears must be in Tricycle configuration with steerable Nose wheel.

->It should fly stable in moderate winds (8~16mph) at ease.

->Wing span must lie around 48", a 4'x3' sheet is enough to build one.

and much to be added.


(requirement for intermediate and advanced flyers)

->Must have High power loading upto 100+Watts/lb.

->Must be maneuverable in moderate wind speeds.

->Must penetrate good in larger wind speeds(>16mph) as well, So Wing loading and Wing cubic loading must be carefully decided.

->Must have really strong structure to sustain with G forces during flight and High G maneuvers.

->Can have Flaps, Retractable landing gears, Channel mixing, Thrust vectoring (Like in advanced jets), spoilers etc.

Now as we want both(beginners as well as advanced flyers) to be happy with our design, We need to make our way in between the above mentioned requirements for beginners and advanced.

so from my side,

Final design must be

->A Mid-Winger with very little dihedral. The CG on the vertical Axis must be placed below the wing to make it equally stable as a High Winger.

->With pusher setup

->With all the power loading required by the advanced ones. Lets fix it to atleast 80~100watts/lb.

->must be a typical 3channel (AET/RET) plane but can be extended for more number of channels to support advanced features like all mentioned above(flaps and.... etc).

->Landing Gear must be in Tricycle configuration with steerable nose wheel.

->Must Have wing loading around 8~10 oz/sq.ft while wing cubic loading must lie around 6~8 oz/cubic.ft.

->Thrust to weight ratio must lie around 1.25:1 or greater to overcome easily from the stalls.

->Must have wing span of 48" to 56".

->Must be naturally stable even in beginners hand and should penetrate good in moderate winds(~16mph) as well.

->AUW must be decided carefully to keep stall speed lower which means flying/Landing at lower speeds
will be possible.

->Must provide good maneuverability.

Do anybody have a design on which we are going to think further and improve it....?

If not....What about this.....!!!





We can start modifying the design as per our needs from here. No issue in that, even I would be more happier than before by seeing my design as the base design in this project. 

Thanks.
Cheers.
 

great Sumeet.. and just waiting for the guidances and adives from all respected Senior Veterans.. 

Thanks Roopesh Sir. I am also waiting for the seniors to get involved in this thread....
Lets see.

thanks Roopesh Sir for the information of Coro. It seems to be a very good material.
Wow Sumeet.....good points covered under requirements!!

hi,

GOt some scanned images from a magazine of Oct 1989, hope it is of help to beginners.

regds

thank you Sandeepji..

hi,

i have a huge database waiting to be scanned, lots of info from nose to tail and wheels to wings.

will be putting it up slowly so that all can benefit. no use to keep the info lying in a cupboard and let mother nature eat it 

As per my experience since 1989 i am building models and have built a no of them right from scratch to arfs. today i have stuck to only coro and stopped building in balsa due to cost and time factor.

my recent designs in coro are very popular and have been flown by many members in our club.

although a slim and curvy model is eye catching but the building process is painfull. i have stuck to simple principle of KISS ( keep it simple & sweet )

pis below.

regds

Great...Now this thread is getting alive.........
 

 

As Rupesh Sir has stated, shall we all stick with a 50" wingspan? Need everyone's opinion on it.
Next...Sumeet has put up an excellent set of requirements. So shall we all stick with that? Need everyone's opinion on it.
I would like to add some more points under requirements:
1. Takeoff Distance
2. Landing Distance
3. Range
4. Ceiling
5. Rate of Climb
6. Stalling Speed
7. Maximum Speed
Now I think we should also decide on the above 7 points.
Please start suggesting....

Guys one important point: lets first fix a set of "UNITS"
Distance : inches? or mm? inches could be a winner since the dimensions are large in aero field.
Weight   : Kg? since we are used to it everyday.
Time      : seconds? same as above
Shall we follow the above units? please suggest if any other form is used frequently. lets have a united opinion on it & fix it.

I would suggest we all keep noting important points, from discussion in this forum/topic, in our notebooks, so that even if our comp is off we can still keep working on our wonderful project....wont keep it idle...not at all...

and we must need the grace, blessings and advices from Seniors.. all Respected Seniors.. please advice and guide us in this project, to fulfill our dream.. the dream of RCI.. 

50" wingspan is just fine.

Now lets discuss on points you mentioned......

"Landing and Takeoff distance"...
As we all know that we always have a problem of a good large Airfield. Most of us are bound to fly in local small playgrounds with lots of activities already going on there. So, A good fix is to keep Takeoff and Landing distance smaller as possible. But on the other hand, It will require the plane to be lighter in weight or should have flaps or spoilers or combination of both.
My opinion is the "distance no more than 20 feet" for both Landing and Takeoff.

"Range"...
I still don't get your idea with the "Range". Is it Radio operation range(Things get pretty unpractical here as the effectiveness of radio is completely a different thing). Or it is the maximum distance the plane can travel at full charge.

I am pretty sure that you meant the second one, The Distance it can fly to...Right?
So, is our plane is going to be specialized in any operation like wild-life tracking or something like that?
before having such goal....I don't think that discussing on the "range" makes sense. After all we are going to fly it as a usual R/C plane, Standing at some place comfortable and flying in loops over and over again. Unless we intend to get our plane to fly pass the certain distance, The "Range" doesn't need discussion. What you and others say?

"Ceiling"....
With respect to aircraft, a ceiling is the maximum density altitude an aircraft can reach under a set of conditions. Copied from Wiki...can read further....
In R/C planes, Ceiling clearly depends upon Radio range + how far above we can clearly judge the orientation of our plane. So, what must be discussed here....?

"Rate of Climb"...
This is a good aspect to determine the ability of an aircraft. Greater rate of climb means faster it is to reach a certain altitude. Need seniors here who have a good R/C flying experience. They can suggest it more precisely as they have flown different aircrafts and can tell the difference between flights.

"Stalling Speed"...
Lets set it to around 20kph...or 4kph more or less? To experience how fast it is....Just drive a two wheeler on that speed and imagine an R/C plane taking off at the same time......I have done it.  

"Maximum Speed"...
As we want to keep plane easy to fly for the beginners but also desirable one for the intermediate or advanced guys. It must have wide speed range. What about 70kph (~43mph) at max....? Is it that good?

Now lets see what others say about it....

Thanks.

nice discussion..

I agree with your opinion on Range & Ceiling.

20 feet is a good takeoff & landing distance

need guidance on Rate of Climb, Stalling Speed and Max. Speed from Seniors

One more suggestion from me...

Why don't we set expected payload for our aircraft...
I am suggesting this because we intend this aircraft to be built by beginners. So there are chances that sometimes the plane will end up more heavier than expected.....Thus, Setting a payload will give an idea of "with what maximum weight this plane could fly". I am referring this as payload because if the plane's AUW is weighing nearly equal to Expected AUW, Then we can think to carry an extra load on the plane(Paratroopers, Dummy Bombs, tiny Bag of floor to mimic explosion once it is dropped, paper cuttings etc). I hope you have the idea now....

For example: Lets suppose the plane's expected AUW is around 0.75KG. while the actual ends up at 0.825KG. It is not a big deal for an advanced or intermediate guy to manage. But for beginners, It will definitely make him think that would this plane fly or not....Even I have asked such questions regarding the increased AUW from others while I too have been asked it many times. So, Lets fix a "Maximum possible AUW" (lets not call it payload as it can cause confusions further).

Another problem here is that we don't know the expected AUW of our plane till now, So, we can go with the formula:

Maximum Possible AUW = MPAUW = P X Expected AUW
(Where P is greater than 1)                              ===>(1)

Now we just have to fix the number P and that's all.

We can also derive P on the basis of maximum static thrust.

P = Maximum Static Thrust/Expected AUW          ===>(2)

By putting the value of P from Eq.2 to Eq.1,

We have,

MPAUW = Maximum Static Thrust

Or in other words, MPAUW must be less than or equal to Maximum Static Thrust to achieve required performance.

Further,

Actual AUW <= MPAUW
It is the condition which needs to be satisfied to fly the plane without any risk...

However the plane can fly even if the condition doesn't satisfies but then it will result in increased stall speed and will require longer runway for takeoff and landing.

Payload can be easily calculated now,

Payload = MPAUW - Actual AUW
It gives the extra weight that can be carried in the flight.

I request to other members to give opinions......This thread is getting more interesting now...

Thanks.
 

great considerations..

hi,

sumeet whatsoever said, are we planning for some kinda competition or designing a UAV.

lot of factors are to be considered during the design process. a number of problems have to be tackled and solved. all this requires patience, time and lots of money.

have been all thru this and now currently into experimental designs like using solar cells and a autogyro.

lots of trainers have been designed and are available, ultimately its the odd aircraft that stands out.

 

Sandeepji, please share possible tips from your years of experience here once.. as it will be great helpful to all..

Absolutely Sandeep sir...It must stand out....and yes....Money and Time are the primary investments in this project. If mentors like you are with us, We don't fear anything. We will definitely succeed.

Well, Lots of trainer aircrafts are already being sold, Build and flown everyday and most of them have satisfied owners. The main thing we should consider is what odd we can do and what we expect with this project. Without knowing our own expectations, we can't design a perfect plane that everybody can enjoy flying. Everybody face some problems when they just start in this hobby. We all learn with our good and bad experiences and that's the key thing. By minimizing commonly experienced problems in model aviation should be the direction that our project should proceed in. So more & more people can fly without problems. If I can play a part in it, then it is an opportunity for me.

Well I know its not a competition. And fixing those numbers like I did was kind of unfair  . But as far as we are on the stage of discussions. We all have right to make suggestions and give opinions. And I just did mine. I don't want to force somebody to follow my opinions. Even I would rather be happy if somebody cuts my suggestion and suggests something else. That way we would have more things to discuss. We definitely need more and more involvement and discussion here.

And yes, Please share your experiences with us as it will be so helpful and interesting as well.

Thanks.
Cheers.
 

What I think is that we are not planning to build an outstanding plane. neither is our objective to sell this plane....or to place it in competition. let this be very clear that we only want to make our basic knowledge very strong. hence we should start with a simple plane...a trainer.....which will cover basic practices....which a novice can also make. thats all our objective is. we need to get to the core of understanding the basic aspects of aircraft design....like aerodynamics, power, stabillity & control, structures, etc. The knowledge thus acquired through covering these design aspects has to be simple in understanding for a beginner. Thats all my objective was. People come here to get this knowledge, but its scattered. What I wanted was a single project which will cover all the basic design process to be in one place. so that a novice can understand step by step what goes on in this beautiful journey...called aircraft design.

Sumeet you havent fixed any numbers...in fact you have shed light on normal practices, which is great!! we all over here need to know what are the basic thumb rules so that we can relate them and combine them with our basic knowledge and generate a real life practical, useful and easy design.
Sumeet you have given really useful details....I appreciate that a lot.

About gross weight.
To keep in mind - should take min. takeoff & landing distance, max. speed, can be hand chucked (though its not advisable for begineers), easy to carry....from home to ground.
So a value of about 800gms max should be thought of.
What are other's opinion?

Thanks Vikalp Ji.
800 grams is fine.
 

buddy i m no ji...just 26 yaar.
 ur welcome

But I am not 26 naa.....I am 22. 

800 is fine, but we should show a breakup of this 800.....i.e what all is included in it.
say electronics weight
1. Atleast 3 9gm servos = 9gm x 3 = 18gm +10 gm for push rod = 28~30gm
2. Motor (brushless outrunner) + prop (plastic/wood) =  150gm + 15gm = 165~170gm
3. Motor mount = 100gm
4. ESC = 35gm
5. Battery = 175 gm
6. Structural weight = 300gm
Total = 810gm
Well this is just an approximate figure, I may be wrong somewhere. I doubt about the structural weight. About the weight of electronics....I got it from sellers website & considered at a higher end.
Need other's opinion too.
My objective here is to know the thumb rule, but to also think about the logic that went into fixing this thumb rule.

Vikalp we can cut down a little weight from motor. as Motors like Cf2822 has wt less than 50gm and thrust of nearly 750 gm. for more thrust we can go for turnigy motor with wt of around 80gm and thrust of 1000gm.
Motor mount wt weight can also be reduced by 40 gm.
In total 80 to 100 gms can be reduced from electronics. which can be adjusted to make the frame more tough by reinforcement.

Agree with Swizera. 

Nice initiative friends...!! 
Would be really helpful for beginners like me..

http://www.rcindia.org/electric-power/understanding-electric-power-systems/msg104023/#msg104023

this is definitely going to help us.....Go through this link.

I agree with that, but those figures are rough. & i wanted to show what all is considered in rough estimation of weight. Once we have that we will proceed with finding critical parameters, like thrust, power....once we have our thrust requirement we can always chose a motor with least weight & cost. A better weight estimate will be carried out later.
We shall keep note about the motor you mentioned.

Now since we have our max. weight estimated, we can proceed to the next step, which is estimation of critical performance parameters. they are : Cl(max), L/D, W/S & T/W. These are governed by our own set requirements of : takeoff & landing distances, stall speed, max. speed, rate of climb.
Please note that we yet have not fixed our requirement of stall speed, max. speed and rate of climb. So before proceeding any further we need to finalize these 3 points. Need everyone's opinion.

I suggest the following requirements:
Max Weight: 800gms
take off and landing distance: 20ft each
Max Velocity: 20km/hr
Rate of Climb: 2ft/sec
Stall Velocity: 8km/hr

Please guide me on this. Need others opinion & contributions too.

This project has stalled.....no participation???

Sorry I was out.....

I think the "Rate of Climb" needs to be greater that 2ft/sec. I mean flying with this low rate of climb will be difficult even for advanced flyers...It will be too difficult to maintain altitude then. Lets just increase it up to around >10~15ft/sec atleast...

Well, Max weight is OK, But Would the plane of this weight can have stall speed and Max velocity so low like 8kph and 20kph resp.? Can we imagine a plane of this size to fly very little faster than average human walking on the street(An average young human being has walking speed of ~6kph)...I am not saying it is impossible but I mean that would need a lot of wing area while we have already set the Wing Span to 50 inches. So, We can only move the numbers around Wing chord. Having the chord too large will aerodynamically need bigger Control surfaces, specially Bigger Elevator surface, for even gradual climbs. So, With the weight 800gms we have to put the stall speed and max velocity little higher. or we have another option, We can expect less AUW but it will then require less Wing area to be aerodynamically what we want it to be.

I have a suggestion from my side. That is, With a wing span of 50", AUW around 800gms, Airfoil type KFM3, and Wing Area 500sq.inch, Our plane will have around 22kph Stall Speed while its max static pitch speed should be 2.5 to 3 times of Stall speed. That means we should look for ~60kph max with our power system. This result is obtained by Motocalc application.

Well I can understand your point of view with your suggestion that Low speed plane will be more easier to fly. But to achieve 8kph as stall speed on a 800gms plane and with a wing span of 50", We would need the Wing area to be around 1400sq.inch (Again Motocalc Data). That means we would need the wing chord to be 28inch Which is less practical for a trainer plane...

And I don't think 22kph Stall speed is fast for a plane of this size.

Waiting for others suggestions.
Thanks.

Hi Sumeet, thx for the information!
Could you please tell me what is the density and Coefficient of lift that you used for calculating stall speed of 22km/h?

Coefficient of density or of drag...?

Here are the lift coefficients of Airfoil(KFM3) I used....

CL = 0.52
CLmax = 1.20
CLopt = 0.64

It is 12% thick, 3.5% Cambered with 2.5% Angle of attack.

Please confirm, Was it Density or drag that you wanted to know.....

Count me in  ...though I am a noob but probably can help you guys in making design sheet etc.

Great. I am glad to see you participating...........

I hope you enjoy this project..........

 

Hey Sumeet, thx for that information.
I meant just density, which I have took as 1.225kg/cu.m.
My idea is to keep Vstall as low as possible & Vmax as high as possible.
So, Keeping the area as 500sq.in, if I consider Vstall of 8km/hr & Vmax of 60km/hr then I need Clmax of 0.87 and Clmin of 0.02. (I converted all units to: kg/metre/second.)
So to achieve that range of Cl we need to play with camber,chord & thickness of the airfoil. Now I am thinking how to vary these three parameters so that the mentioned range is achievable.
My objective was to see the plane fly so slowly too....thats it.

You can try it....

Motocalc 8.0

Above application with which I calculated doesn't needs Air density but Sea-Level Air Pressure. And the value I fed is 29.92 inHG and Altitude which was set to 1700ft (As I live in Indore which is situated on top of a plateau called "Malwa Plateau"). Just calculate again in Motocalc. It can tell us better what we have to do.... 

Thanks.

Meanwhile I calculate, we can continue with the values that you have suggested.
Lets not pause this project....

As most of the parameters are set. Let's talk about design. How it would look...?

Any suggestions...?

So the design requirements have been set to:
1. Max. weight - 800gm
2. Takeoff Distance - 20ft
3. Vstall - 22km/hr
4. Vmax - 60km/hr
5. Rate of Climb - 10ft/sec
6. Landing Distance - 20ft.

I am a complete noob. Built a trainer out of coro which did not fly. So I have started designing a complete coro pusher on my own from the experience I have gathered. Please correct me if I am wrong:
A wingspan of 50" using coro will flex quite a bit. Since we are keeping the costs low (I have to ) I am not considering CF rods or depron. So is it possible to decrease the aspect ratio and still retain good glide characteristics?
An AUW of 850gms seems right to me!