RC India

HI
I am beginner scratch building a Big Beaver Foamy.
I am new to the hobby with a little knowledge of electronics.
The specs of my home built are

Airframe weight 390 gram.
Expected AUW around 800 gram ( excluding battery )
Wing Span 62 inch Chord 7.5 inch

Motor  Turnigy G10 1100 Kv Brushless outrunner ( http://www.hobbyking.com/hobbyking/store/__14403__Turnigy_G10_Brushless_Outrunner_1100kv_.html )
Esc Hobby King 40A
Servos 4 nos. 9gram ( Ailerons 2, Rudder and Elevator )

Can you experienced modeler please suggest me a good lipo battery ( specs and brands ) for this setup..
I am very confused which batteries to buy. Please suggest should I buy from Hobby King or some local Hobby shops
How good are the Indian Batteries ( IndPower ) etc
I want a decent flight time ( around 10 to 15 mins )

Other question is about the motor
Is this motor sufficient for the current configuration or is over rated..

Thanks in advance for your valued suggestions..

regards
Umesh

Post some pics..

Hi friends,
I am new to the hobby with a very little knowledge of electronics or aviation. I decided to scratch build some model and found Big Beaver to be very attractive and easy for my first model, though I was advised to start the hobby with some slow flyer trainer.
This thread cannot actually be called  a build log because I havent been logging progress of my home built .. but I had to do this coz every time asked the seniors for help it was difficult to do so without looking at pictures.
So in the Hope of getting support from experienced flyers and modelers heres the pictures...
Now on I will be logging the progress of my build on a regular basis ..

thanks

Great Finish, Material looks very good, what is it ( pink foam ?) and where u get it? pl provide details and more pictures.

Dear Umesh,

What is the material you used ??? how strong is it??

And very nice finish you have given.

Thanks..
The material is Extruded Polystyrene also known as Pink Foam or Styrofoam ..  manufactured by Owens Corning company. It is easily available with stores who sell insulating material like glasswool etc. Its a very popular material with aeromodelers the world over because of its light weight, ease of use and strength.

Quote from: umeshk on July 26, 2012, 03:43:12 PM
It is easily available with stores who sell insulating material like glasswool etc.

Hi Umesh,

Can you please provide shop details where you bought it from india ?  (:|~

May not be helpful for me but defiantly help enthusiast from Rajasthan. :salute:

-Vinayak.

This is available at Daksha Enterprises, Gopal pura bye pass. Ph 9414060994. But they keep 40mm and 50mm thick only.. You will have to hotwire split them to desired thickness..

Thanks  :salute:

Time to fix wings... but stuck with Dihedral...
Can any one please suggest me the Dihedral angle...
the wing is  29" from root to tip and the span is 64 inch.

thanks

My Big Beaver now Almost Ready To Fly...

My Big Beaver now Almost Ready to FLy...

your motor is capable of only upto 3Cell,
1. 1800mah 3S will keep the weight down and give you enough power,

2. what i am curious about is your pull-pull, change over to a cobbler's thread instead of this steel wire.

3. also change your 'Z' bend on the elev, the bend isn't clean. It will slip in when moved.

PS
Who is maidening? depending on who might have some tips (Since i own TT Beaver)

That's a big one! All the best for the maiden.

Do you have any pictures at all for the hot wire process? I have some blue sheets lying around but haven't dared slicing them for fear of destroying them. They are in 25 mm and 50 mm thickness and I want to slice them into 5mm sheets.Your help will be appreciated.

Completely agree with rcpilotacro. Better straighten up the z bends before you maiden her or else you are asking for trouble. This baby is going to smash into a few pieces on impact. Here are two videos that may be of help:

http://www.youtube.com/watch?v=TBJHmDuphJc

http://www.youtube.com/watch?v=2CUtIwvc_ow

Thanks VC for the wishes..
Unfortunately I didnt keep a picture log of the build but you can find a lot of resource on youtube for slicing...
I used the thinnest guitar string which is a nichrome wire and power supply from the transformer of my old stereo system. Marked 6mm  on either sides along the length of a 50mm sheet and screwed two long strips of wood ( for guide ) on either sides. Tied curtain hooks for grip on the ends of the wire and applied power. that was the easiest I could device. Youll need to sand it for a uniform finish ( the reason for 6mm marking insted of 5 )
I carved out the airfoils using the same technique ... .. though one wing was destroyed in the learning process..
believe me , once youve mastered the technique .. its the easiest and an instant method to make airfoils..
My best wishes ... go ahead coz 5mm sheets was impossible for me to find.. and if you slice a 50mm youll have loads of foam to work with..

Umesh

nice build @umeshk

@rcpilotacro and @vc - I feel the z bend seems to be just ok on the servo side (just the bend), the linkage to the control rod surely has a high chance to slip (unless changed or at the least glued). Were you pointing at that? I could not notice any z bend on anycontrol horn on the elevator surface, or did you mean the z bend is too wide for the hole on the servo arm and will slip within. I know I've just confused what I'm trying to say so here's a picture. Let me know if I'm missing something. Sorry if I'm being dumb but unless I ask, I'll remain dumb. :D


I agree with the wire on the rudder/tailwheel servo, it might just flop when pushed.

the bend will slide into servo horn if doesn't have clean 90 deg, also the bottom bend should not be too long either. Umesh, i also noticed you rudder hold down servo screw is missing. did you just keep it there put some glue and thought it will do? i suggest screw it in ;)

Aha! I see what you mean.
+1 on the screwing it in. healthy for the servo as well, keeps it aligned.

a screw or two is always healthy ;)

PS
since the whole thing deals with your beaver topics merged

I feel it would be little tough to get CG right.....might have to add lot of weight along with motor.
Try putting a iron sheet as motor mount rather than adding other weights it will give strength and weight both!!!!

Thanks rcpilot, VC, Girish and  guys for the help and suggestions ...
The wire for the pull pull is thin steel wire with vinyl insulation . Its a very tough wire for its thickness , is used for semiprecious jewellery bead strings.. I could save a few grams but the wire was too thin for the push rod stopper so I has to attach small wire pcs at the end.. any suggestions ??

I am surely going to screw the servos and replace the wire holding bamboo pushrod with a piano wire . I didnt have one and I was in such hurry to test my setup that I used whatever was available ( A hair clip ) . Thanks for sharing the Z band clip. Please check the Z band and servo positions for ailerons and advice.

I couldnt find anyone in Jaipur for the maiden and I haven flown anything in my life except paper planes. So I am looking for some used autopilot and  a simulator.

once again thanks for your valuable suggestions...

Thanks Saurabh...
where exactly should be CG.. Should it be 35% from  LE..
The chord is 7.5" .. is 2.6"OK  ??

CG at 20% Chord, autopliot and such gizmos wont do, i hate to see this beauty crashing. get someone experienced to maiden this beauty

Gusty Boss, why for this plane CG at 20% against 35%???? did not understand???

If its 20% then its more problem setting CG.... Umesh I tell  you, you've done fantastic job on this plane.
want to advice a few points......
1. Do not be in hurry to fly this plane - no matter what .....
2. The plane built is very good BUT the structure and material will NOT sustain even a slightest of jerk & it will be into pieces.( no spar in wings or wooden support in fuse....in-fact your motor mount should have been a block of foam with screw studs to fix plywood)
3. In worst case be prepared for it
4. As i see youve invested into getting horns, clevis etc.... don't do a "chalta hai" job with control rods and z bends
I have searched and waited for these things a lot..... go to tirpolia bazar cornor shop when you turn from chaura rasta to tirpolia ( towards choti chopar) {other will not understand what i am writing } there is a hardware shop which sells only wires ask him to give you steel wire used for pulling electrical wires inside contudes (in a new house construction). and he will give you the control rods !!!!!!!!!! (steel wire 0.8mm dia).
5. Dont let them lose in fuse ... use a empty refill to guide them by sticking small piece os refill on the fuse base. This will give them some guide and restrict stray movements.
6. Check , counter check & again check CG {most important} see videos on how it should be..
7. Find a experienced person to fly.....or atleast who knows how these things can fly...... you would be surprised to see what we normally think on how to use TX sticks actually the movements are just like pulses to control surfaces very slight movements... any first flyer would make mistake and over control the elevator or aerilons.
8. Knowing this much and making a good ( as people say) scratch model I could not fly my own plane for more than 20-30 sec when I took it in mid air... it is tough for first timers.
8. I am sure once you crash it you will lose interest in this hobby by not getting any o/p after so many efforts.
wait and try improvising search material and means to strengthen it.

OR if you think it is possible ..... keep this plane as it is ... make yourself a smaller plane ( make some thing like a chotu SPAD (search in this forum or ATOM from HK) experiment and learn how to fly then take onto your big plane.
At first this may look weird advice but trust me it will let u have fun with your plane.....

I guess at 35% (66mm) it should be just slightly nose heavy. At 20% (39mm) it should balance perfectly. Gusty please elucidate..................I'm following the same thumb rule for the Avispad.

As per what i have read..... we should have CG at the place where wings are thickest & we should have aerofoil shape such that the thickest part is at 35% of chord.

That is the place we have lift force acting so balancing cg at this point keeps plane horizontal.

@ VC - Unless done you will not know is the plane nose heavy or tail heavy.... You need to fix the CG point then add/ remove weight to make it nose / tail heavy.

Lets hear from Gusty ( rather learn from him) what he has to say.... Sir....

I beg to differ here. All models can't have a CG fixed at 35% from the L.E. It depends on the flying characteristics of the model. The faster the model is designed to fly, more forward will be the CG. Gliders can have a CG as far back as 35 - 50%. Warbirds as far ahead as 20%. It also, therefore, depends on the wing aerofoil shape.

Sundaram, stop reading and start participating! ;D

Yes i accept that difference of flying characteristics......

But this plane is more of a glider ?????? ( am i wrong or right)

To begin with I always go for CG at <= 30% Chord for maiden of a straight wing without any sweep forward or back to have it slightly Nose heavy to have it manageble to fly it. other wise it will pitch up moment you open throttle, sink tail and stall on throttle cut, will not glide down easy for land and it will have to be flown in forced down to land it, even then it will be difficult to manage.

Once established flight characteristics I push CG back based on performance.

PS : VC Stop prowling On Me ;) ;D

I agree on your last post. I believe CG <=20% is too far ahead for RC unless it is a very high performance wing aerofoil or canard models, forward swept wing.

I am a fast learner Sandy. I have some brilliant teachers based in Meghalaya.

 :hatsoff: Thats to you VC.

I am signing Off to witness birth of Lord Krishna. Adieu

God bless. Good night.

20% is based n the pic umesh posted, critical aspect is who will maiden it, without the required skill set she will go down in flames

Gusty I believe you have miss-spelt as nose heavy at 35% I suppose .  If you are able to balance CG at 35% or more you have actually managed a tail heavy characteristic plane. You have to add/shift  weight forward to balance CG ahead at lesser percentages of Chord to have a nose heavy plane.

Thanks a lot Saurabh Boss for sparing time and posting.
How do you know so much about jaipur... have you been living here... how often do you visit ... may be you can help me with maiden flight. Would you ??
After this I have dropped the idea of flying this plane at all and planning to build a primary trainer instead.
I am definitely worried about the strength of the frame and finding ways to strengthen it.
Can I apply a coat of epoxy on the expense of adding some weight ???
I do have spars upto about 8 inches ... should I add one more along the length...

regards

Thanks a lot vc boss, sundaram boss, rcpilot boss for the knowledge...
Now with a lot of feed backs pouring in I know I am not a lone builder ..

I have atleast understood that CG is more complex than what I thought it was !!!
And it has to be between 20% and 35% ..  ;)

Actually I am also worried about the tires tripping into something while takeoff and breaking prop, if its nose heavy... is my worry legitimate..   ???

thanks

That would depend on a few factors. Where are you taking off, how strong are your wheel supports / legs, how big are your wheels.

Your wheels look the right size, however, I can't make out the main undercarriage assembly from your pictures. How have you bolted it to the fuselage?

The tail wheel looks a little too big (same dia as the main wheel?) and the spring assembly is good. What you want to do is to brace the pink foam with light ply / balsa (where the spoke enters the fuselage) from both sides.

Sorry I misread the above post. I thought you were worried about the wheels getting ripped off during take off / landing. If you are concerned about prop breakage, use a prop saver.

you tailwheel rubber has the tendency to come off, needs a little CA(foamsafe) there

Your plane is to big to suggest fevicol & tissue coat etc etc..... such a plane is basically made on 3mm Ply or Balsa wood frame.
At the max try getting wooden sticks get then 2-3 mm thickness and embed along the fuse and wing base.try making a frame at the cockpit for strength.

Thanks VC boss .. noted your suggestion for re-enforcement..
now Can someone help me the Dihedral..
currently its around 6-7 degrees. Now I have to fix the struts and planning to freeze them at 5 degrees... will it be OK... I dont know how to calculate the angle and I am confused with the resource available on the net ...

thanks

I found something
http://adamone.rchomepage.com/cg_calc.htm

Hi all,
after the unsuccessful  maiden of my Big Beaver and crashing it for thirteen times I have given up on it and spared the little thing until my new scratch built blue baby is ready for flying..

Hi Umeshk,
I had also started the route you have taken. I built and crashed 3 models before good sense prevailed and I got hold of someone ( Divay Puri in our field) who helped me with basics.

Try to get hold of a local guru

regards
Pankaj

Aaahmm.....not a guru.....but yes enough to put u on a fast track.... :hatsoff:
By the I was in Jaipur for last 6 days

But all the same... Has any one compared this pink foam to depron? Would like to understand how they stack up

pankaj

thanks saurabh and pankaj,
ill definitely need your help saurabh... for the last few weeks i was stuck up with business and all ... was working overtime burning midnight oil to complete Blue baby by tony65x55 from rcgroups. now its almost ready will try it out ..
Pankaj I may be i was lucky enough or its the pink foam that despite my dumbthumb my beaver managed to survive... Its the only material I could manage to source here in jaipur.. would love to work with depron too..

Likewise Umesh, I work primarily with depron (aka biofoam) would love to get hold of pink foam.

Depron is not biofoam at all.  Haven't seen depron locally much.  Biofoam/foamboard is an entirely different animal.

Anwar.
This is possibly the first time i have been told that biofoam and depron are two different things. However as per my understanding. Sunboard is pvc materials and altogether different.

I meant to say foamboard, not sunboard. Above post updated.

Read a few posts starting from here :

http://www.rcindia.org/rc-general-topics/can-a-flat-wing-glider-fly-with-only-motor-on-it-just-one-channel/msg24971/#msg24971 

After seeing what biofoam / foamboard as it is available locally in India and real depron, the difference is huge.   

Well.. Too bad that i cannot experience the real stuff..
However once at a Clas Ohlson store in Oslo i saw a sheet material marked as Depron that was rolled up and looked like EPP.

That is one of the big differences... true depron handles bends much better than biofoam.

Did you fly the Beaver ?

Yes I did... the experience was bad... I crashed it around 10 times before sparing its life.. later i came to know that the reason might be that it could never achieve flyable speed coz i was taking it off from grass. Had no previous flying experience. but then I was able to fly my friends Dolphin glider reasonably well and realised what went wrong.. Ill upload the videos and would appreciate if you could guide me.. I really love that plane and would like to continue with it..