RC India

RC Models => Electric Planes => Topic started by: Bilal on July 09, 2012, 07:08:27 PM



Title: Scratch Built CESSNA 185 Build Log
Post by: Bilal on July 09, 2012, 07:08:27 PM
Good evening fellas,
I've been introduced to this wonderful hobby by my brother in 2008 and since then I've been reading about it on various forums on the internet, and tis now that i found myself knowledgeable enough to try my hands on scratch building a high wing trainer.

After deciding this I started eyeballing various threads here and on RCG and finally found this plan of Cessna-185 that i really liked and decided to try it as my first plane

here is thr link to original thread on RCG:-
http://www.rcgroups.com/forums/showthread.php?t=1190685

Following are the specks of the plane:-

Construction Material: high density thermocol from fish box and from refrigerator packing material

Wingspan: 41''

Power system: not yet decided, depends on the weight of the complete airframe

following are a couple of pics of the build so far......the airframe would be completely scratch build


Title: Re: Scratch Built CESSNA 185 Build Log
Post by: rastsaurabh on July 09, 2012, 10:58:14 PM
Hi Bilal,

I have seen your crafting its good ...... rather than the cesna TRY this look alike its good plane easy to understand and build.

http://www.youtube.com/watch?v=jv3D30RGT-g

Also have a look at what i attempted..... i used the thermacol from packing of TV, fridge. That is equally good high density thermacol.

http://www.rcindia.org/electric-planes/scratch-building-a-look-alike-of-axn-floater-or-fms-800-or-easystar/msg108284/#msg108284

Power system is same as AXN floater.


Title: Re: Scratch Built CESSNA 185 Build Log
Post by: Bilal on July 09, 2012, 11:09:52 PM
Thanx Saurabh Sir(?) for your sugesstion but i have started working on the plane and in fact the fuselage is almost complete,...i only need to add a rudder and landing gears to it and it would be complete.

Actually my internet connection is darn slow ritenow...else I would've posted a couple of pics of the build.......but will try in the morning.

And I've seen your AXN thread....and i must say, you've got great crafting skills....atleast with thermocol:D......in fact your build log inspired me to try thermocol insted of coro for my first build.....sooo thanx


Title: Re: Scratch Built CESSNA 185 Build Log
Post by: rastsaurabh on July 09, 2012, 11:31:49 PM
Why a question mark after sir......?
I am also a new person in hobby but did my engg. in 1996 !!!!

So with age perspective you can leave sir as it is and remove (?). ;-)


Also you posted your idea after you built the fuse.....!!!! but did you do exactly the same as mentioned in the thread??


Title: Re: Scratch Built CESSNA 185 Build Log
Post by: Bilal on July 09, 2012, 11:40:14 PM
Ok Sir, as you wish;)
and yeah i followed the exat build procedure as stated in the build log on RCG......infact I kinda liked the techneque of using centre block for fuse construction as it enables building your fuselage nice and square without any wrapping.
I did try using treditional technique using formers and stringers(just replaced balsa with thermocol) but didn't get any success.

And one more thing Sir, how did you build the wings for your AXN....i really liked that polyhedral it had and the raised wingtips.....did you hotwired it or shaped the entiere wing by sanding?


Title: Re: Scratch Built CESSNA 185 Build Log
Post by: rastsaurabh on July 09, 2012, 11:47:43 PM
I got the basic shape through hotwire...... Found hotwire cutter very good once you have the right kind  and right skill...
After getting the aerofoil shape on flat wing i have explained on reply no 58...

http://www.rcindia.org/electric-planes/scratch-building-a-look-alike-of-axn-floater-or-fms-800-or-easystar/msg108426/#msg108426


Title: Re: Scratch Built CESSNA 185 Build Log
Post by: Bilal on July 18, 2012, 08:39:12 PM
Status of the build so far- fuselage completed with newspaper covering and controll surfaces attached, it just needs a landing gear


Title: Re: Scratch Built CESSNA 185 Build Log
Post by: abhay on July 18, 2012, 09:32:29 PM
Hey bilal!! What are u using for landing gear? can u post the original specification of wings etc which u intend to build? or it is the same as in RCgroups.


Title: Re: Scratch Built CESSNA 185 Build Log
Post by: Bilal on July 18, 2012, 09:52:30 PM
Yeah Abhay bhaiya......all the specs are same as in RC Groups thread.
I just wany yo know the location of the main landing gear and the distance between the two wheels.
And FYI, i intend to make a tail dagger type landing gear


Title: Re: Scratch Built CESSNA 185 Build Log
Post by: Bilal on July 18, 2012, 10:23:02 PM
I made a sort of latch on fuselage top to fascilitate me while installing pushrods, will glue it back after final adjustments.
I covered the entier fuse with newspaper and 25% diluted solution of fevicol, and i must say it came out very well, smooth and glossy and without any wrinkels


Title: Re: Scratch Built CESSNA 185 Build Log
Post by: Bilal on July 18, 2012, 10:28:06 PM
The original designer on RCG sugessted the rudder and the elivator to be build from 6mm depron, but since I didn't had any, I tried another method.
I build the frame of elivator and rudder from some 3mm balsa I had lying around, filled it with thermocol and sanded flush and finally covered it with 1mm foam and voila, I had some nice and stiff stabelizers


Title: Re: Scratch Built CESSNA 185 Build Log
Post by: Bilal on July 18, 2012, 10:32:09 PM
Since someone said, 'pics are better than a thousand words' :)


Title: Re: Scratch Built CESSNA 185 Build Log
Post by: Bilal on July 18, 2012, 10:50:54 PM
Now one question from the forum members-
the plan suggests a slightly underchambered wing, something like 'naca 1224' and i want to go for a flat bottomed 'clark y' due to the ease of building......soo please suggest which airfoil should i choose?
And one more thing, please suggest a suitable paint scheme, something that is clearly visible in the sky for orientation as I am a newb


Title: Re: Scratch Built CESSNA 185 Build Log
Post by: VC on July 18, 2012, 11:22:59 PM
EXCELLENT work on the Vertical tail and the stab! :hatsoff:

My Cessna has an under cambered wing, but I guess a flat bottom would work just as well.

As far as the paint scheme is concerned, go for dark undersides and some stripes on top of the wing. It will help so that you don't lose the orientation of the model in flight.

Some reading material for you:

http://www.rc-airplane-world.com/rc-airplane-disorientation.html

http://www.rcgroups.com/forums/showthread.php?t=867259&page=655

Picture courtesy www.rcgroups.com. (I hope that they don't mind)


Title: Re: Scratch Built CESSNA 185 Build Log
Post by: Bilal on July 18, 2012, 11:54:19 PM
Thanx VC Sir......your comments meance a lot to me
Sir, can you throw some light on the position of the main landing gear in tail dagger configuration....i mean it should be directly under the CG or slightly ahed of it?
And also, what diameter wheels should i use?

And as far as paint scheme is concerned, i was eyeing this one ;D


Title: Re: Scratch Built CESSNA 185 Build Log
Post by: Bilal on July 19, 2012, 12:00:51 PM
Good evening everyone,
I know i am being impatient here, but I have just a week a vacations left and want to complete atleast the fuselage.....soo please help me out by giving your precious comments on following issues-

1. What should be the position of main landing gear in taildragger configuration....directly below CG or ahed of it?

2. What should be the distance between the wheels of main landing gear?

3. What diameter wheels should i use?

4. And whai should i use as pushrods and how to install them?

-regards
 Bilal


Title: Re: Scratch Built CESSNA 185 Build Log
Post by: Bilal on July 19, 2012, 05:57:31 PM
5. And one more thing, where should i place the control horn?....i know that the holes must align with the hinge line but what should be the position of the horn itself, i mean ai what hight from the base?


Title: Re: Scratch Built CESSNA 185 Build Log
Post by: khan on July 19, 2012, 08:39:48 PM
that's a really nice work i did build few thermocol plain but never this good and at that at time i only had 1ch tx so all never took of from the ground but rode like a car...now im going to make one...i used hot glue few times on thermocol but it made right through it..is there a specific one to use...and instead of using the brown paper u can also toilet paper it makes really hard surface {:)} {:)} (:|~ (:|~    what motor did u use and how much


Title: Re: Scratch Built CESSNA 185 Build Log
Post by: Bilal on July 19, 2012, 09:07:07 PM
Khan Sir,
I dunno about the hot glue, I just use plain old PVA glue of 'Jivanjor' brand. The key here is to lightly sand the thermocol and apply a really thin coat of glue on both the surfaces and wait for a couple of minutes....and when the glue is still a bit tachy, attach the foam and wait it down for a good bond.

I have found that allowing the glue to dry a bit before actually gluing the parts together, reduces the curing time conciderably


Title: Re: Scratch Built CESSNA 185 Build Log
Post by: VC on July 19, 2012, 09:16:41 PM
I hope you find some answers for the landing gear installation here:

http://www.rcindia.org/electric-planes/avispad-build-log/75/

Am updating the thread so please check after 15 minutes.


Title: Re: Scratch Built CESSNA 185 Build Log
Post by: Bilal on July 19, 2012, 09:21:49 PM
VC Sir,
am closely following your thread........tis actually been my savior till now, thanx


Title: Re: Scratch Built CESSNA 185 Build Log
Post by: bhaveshsangani on July 19, 2012, 10:52:40 PM
 {:)} {:)} {:)} {:)} {:)} {:)}


Title: Re: Scratch Built CESSNA 185 Build Log
Post by: VC on July 19, 2012, 11:03:07 PM
Whatever you do, don't follow Hitesh / Maserati's build log. It will freak you out. He has taken perfection to an exalted level. My Avispad is like a novice, first timer build when compared to his construction.

Check this out: http://www.rcindia.org/gas-glow-nitro-planes/my-new-built-coro-cub/msg109567/#msg109567


Title: Re: Scratch Built CESSNA 185 Build Log
Post by: rcpilotacro on July 20, 2012, 06:15:43 AM
1. What should be the position of main landing gear in taildragger configuration....directly below CG or ahed of it? About an inch ahead of it, else she will topple over, on or near CG will also have the same effect, due to rolling friction

2. What should be the distance between the wheels of main landing gear? that is called the track, should be atleast 1/4 the span, give or take

3. What diameter wheels should i use? nothing hard and fast on that, if you look at multiplex fun cub the wheels are big, in you case keep it light could be about 1.5 to 2 inch wheel

4. And what should i use as pushrods and how to install them? cycle spokes, umbrella rods, or a lighter version is two 'Z' bends using safety pin and a balsa stick/carbon rod in between

5. And one more thing, where should i place the control horn?....i know that the holes must align with the hinge line but what should be the position of the horn itself, i mean at what height from the base?
In line with the servo, so that servo is not loaded, remember it is the horn which transfers servo push pull force to the control surface, so that needs to be reinforced.

Few other thoughts
I have seen many start the hobby with making a model, painting them nicely and crashing in the first flight, then they come here sell off the stuff and quit the hobby. So that it doesn't happen in your case, keep these aspects in minds:-

(a) Ensure you have done enough sim of the same model. should be able to take off do some aeros and land at the same spot with same speed every time.
 
(b) For a newbie, it is preferable to let some experienced to do the maiden.

(c) Don't worry about beautifying it, just differentiate the top and bottom surface of the wing and fly it stock, fine tune it (if it survives), then go ahead and beautify. with that, even if it crashes you are not too attached.


Title: Re: Scratch Built CESSNA 185 Build Log
Post by: maserati on July 20, 2012, 10:11:44 AM
good going bilal..
your fuse looks beautiful.actually my internet connection was out of order for a long time.saw your post yesterday.
i know its a tough job to cut thermacol with such precision and then to sand it to give it a final look.i had  a tough time when i made my first plane of it..best of luck for your maiden..

regards..
hitesh..


Title: Re: Scratch Built CESSNA 185 Build Log
Post by: asinghatiya on July 20, 2012, 10:20:06 AM
1(c) Don't worry about beautifying it, just differentiate the top and bottom surface of the wing and fly it stock, fine tune it (if it survives), then go ahead and beautify. with that, even if it crashes you are not too attached.

It reminds me those beautiful lines, ;   "Ghar ko sazane ka tassuvur bhaut baad ka hai...pahle iss ghar ko bachaya jaye"


Title: Re: Scratch Built CESSNA 185 Build Log
Post by: rcpilotacro on July 20, 2012, 10:31:04 AM
Irshad Irshad

Bilal

One other thought, get your CG correct, do final check of control movements before take, read this thread http://www.rcindia.org/beginners-zone/conquer-your-maiden-flight-woes!!!/


Title: Re: Scratch Built CESSNA 185 Build Log
Post by: Bilal on July 20, 2012, 10:19:05 PM
Hi everyone,
i tried to hot wire the wing cores from thermocol, but dunno what went wrong and it came out to be a disaster.

I made the templates from sunmika, sanded their edges smooth and even sealed them with CA, but still see what the result was........am i missing something here? :'(


Title: Re: Scratch Built CESSNA 185 Build Log
Post by: abhay on July 20, 2012, 10:38:28 PM
Bilal, use sandpaper and sand out the wing,instead of cutting with hot wire. First sand it with rough ones like No.60 then later on you can go for finer ones like 100 or 200. The finishing you want,you can get after covering.

Regarding hot wire,Hot wire can always be mess if you cut long span.
have u used any spring with wire cutter?


Title: Re: Scratch Built CESSNA 185 Build Log
Post by: Bilal on July 20, 2012, 10:42:12 PM
Abhay bhaiya, am using bunjee cord for tention, why?


Title: Re: Scratch Built CESSNA 185 Build Log
Post by: rastsaurabh on July 20, 2012, 11:53:24 PM
hi bilal,
I must say a very decent job for the first attempt..... This is a skill and it requires lot of practice.
How is your setup???? you need not put Spring or tension if you are cutting wing in parallel. In that case your wire should be tight and it all depends on your hand movement + what is the voltage / current through the wire.
Could you explain how you  are cutting i can suggest you some solution....

DO not use glued surface to cut with hot wire.... it will not give good results since wire gets stuck at glue.

See some u tube videos with " wing cutting by hot wire" i must say its the best way to get wing smooth and rigid. 

Can you share the aerofoil shape and source?


Title: Re: Scratch Built CESSNA 185 Build Log
Post by: Bilal on July 21, 2012, 01:18:37 AM
Saurabh Sir,
am using a step down transformer to isolate me from the line which has a secondary output of 3V-31V.
The wire am using is a 18 guage nicrome wire, 30'' long and it graws about 2.5A-3A. Am using a dimmer switch in seriese with primary of the transformer to controll the heat of the wire

the airfoil is Clark-Y with 20%chamber at 40% chord. Chord= 17cms


Title: Re: Scratch Built CESSNA 185 Build Log
Post by: rastsaurabh on July 21, 2012, 07:41:14 PM
Secondary O/p is 3V to 31 V ?? must be with dimmer!!
with what you are holding the wire???? I mean you have a bow for holding the wire or you are using it with hands??

Are you cutting the entire wing span??? have to do it Half wing at a time.

Also see if the thermacol is proper in a low graded thermacol you have certain particles which do not melt hence wire gets stuck.

best way is to have a Bow with Nichrome wire and guide it slowly & smoothly a single glitch and its gone!!!!

Have a look at the utube video you will get idea.