hi guys

this plane will be a simple 2 channel model good of beginners or people looking to start of into rc by scratch building

target weight of ready to fly will be under 300grams

Equipment :1. one 3.7 grams DYS servo
               2. futaba 4 ch AM 72mhz receiver
               3. 7.4v @ 400amh lipo Hyperion battery pack
               4. one brushed ESC (my own)
               5. one GWS EPS350C geared setup (6.60:1)
               6. one GWS EP orange DD prop 10x6 inch

               futaba attack 4 AM 4 channel transmitter.

the plane isl built using packaging foam (high density thermocol or EPS 22kg type) n 10mm fiber glass boom. plane

design will look like a stick type model in pusher configuration !

sahil

update

1st up will be the wing, i have decided to built the wing using low density EPS foam locally available at book store with 10mm fiber glass as reinforcement half way through.

wing dimensions

span 39 inch
chord root/tip 9.75 inch
chord thickness 1inch
spar at 1/3rd of chord-8.333inch
Aspect ratio A/R =1:4

to construct the wing one needs a 1 meter by .5 meter by .5 inch thermocol sheet, cut the sheet into 4 equal parts of .5 meter by .25meter, now cut a grove to fit the fiber glass tube at 1/3rd chord from leading edge of the wing to a lenght of .25 meters on all four thermocol pieces and glue two pieces to form a basic wing from which simplex airfoil will be cut

see pictures for info

Hey Sahil,

Only 2ch? Does it fly up and down?

And How you gonna connect the only servo to rudder or elevators or ailerons?

Am so anxious to see how?

MEROG

QuoteHey Sahil,

Only 2ch? Does it fly up and down?

And How you gonna connect the only servo to rudder or elevators or ailerons?

Am so anxious to see how?

MEROG

its a rudder only model, altitude can be controlled by motor !

Which glue do you recommend for sandwiching the thermocole sheets. Don't you think normal thermocole is too brittle ?

Rao

Hi can anybody tell,

how the up and down or altitude can be controlled thorugh throttle in 2ch? 'Coz I need this when I try to fly my indoor 2ch foamies!

Awaiting your reply...//MEROG

increasing throttle results in pitch up and decreasing the throttle results in pitch down.

QuoteWhich glue do you recommend for sandwiching the thermocole sheets. Don't you think normal thermocole is too brittle ?

I'm using FEVICOL SH, also to get a good joint the trick is to lightly sand (see 1st picture one can notice a difference in shininess) the themocole sides which are being joined so that it will bond better n stronger but the fiber glass tube was glued using 24hr standard Araldite (blue box one's)

the reason for doing this is (sandwiching the two sheets)

1. compare to one single piece it will have better strength in terms of breaking due to the fevicol holding the together n
   forming something like a three layer sheet similar to a car glass wind shield which prevent shattering of glass in an   
   accident etc.
2. secondly its very easy to install the fiber glass tube correctly and glue every thing nice and strong !
3. coming to your point of brittleness, i would rather take advantage of the bounciness of the material and by doing the
   steps one,two and also cover the finished wing half with single layer of packaging tape (brown stuff,one can also get   
   them in different colors) will give it an near unbreakable like features

note: one can still get dents n stuff and as a whole its hard to break the wing based on my experience (slow fliers) !

sahil

Quotehow the up and down or altitude can be controlled thorugh throttle in 2ch? 'Coz I need this when I try to fly my indoor 2ch foamies!

let me put it like this, the motor I'm using is connected to a electronic speed controller (ESC) then to a battery. The ESC will control the power being sent to the motor from the battery which i turn reduces the output power making the plane come down or vice verse make the plane go up hence altitude control or up down.

sahil

update, last night i cut the airfoils from sheet metal and nailed it to the side of the wing block will cut the wing when i find time.

Sahil,

Can you find any solution (cheap) for 5 min bonding for thermocol?

MEROG

QuoteCan you find any solution (cheap) for 5 min bonding for thermocol?

well, Fevicol if applied in right quantity on thermocole will bond with in 10min and has good strength .

update, finished cutting the wing (it came out okay but needs light sanding)

the foam cutter i have used is a simple n light weight structure made from aluminum with self load spring design.

Spec.

1. 35 inch long bow
2. 17inch width
3. music wire as heating element
4. power supply is via regulated 12volts @ 2amps 

see pictures for more details.

sahil

never thought tat cutting a thermocole will be this simple using homemade stuff. can u tell some more info abt this music wire?

update, the wing is almost done just need to give it name n cover it with tape 

hi akash

Quotenever thought tat cutting a thermocole will be this simple using homemade stuff. Clap can u tell some more info abt this music wire?

music wire or guitar string is the primary part of the foam cutter where power is passed through it, the string heats up (high resistance) which is held tough by a bow kind of system, the hot wire is passed through foam via template which gives the desired shape to the foam (thermocole)

for more details try Google search (word foam cutter)

sahil

wing before covering, and named the model GARUDA (wiki for meaning)

sahil

Dear Sahil,

I have tried a lot to make a handy foam cutter with guitar string (3rd Steel) and a DC adopter of 12v across it! But it didnt catch that much heat enough to cut thermacol!

If it really works for you, can you please tell me how much voltage you have given and how you have connected the string?

Awaiting your reply...//MEROG

Merog

Why dont you just use a 12v battery (7000mah... usually used in 500va ups systems) and connect it across the music wire (thin guitar strings also serve admirably). I have used this method a few times to cut foam. But the daunting part is the bow and how the bow is suspended from the sealing.

Have fun

Saju

Thanx for the suggestion,

Actually I tried, without creting tension at all in the string. Thats why I think the heat was not produced. Somewhere someone has used 25v, with tension in the string. I knew now that tension is must either way of use of voltage!

And am planning to make a frame with variable tension (I mean, in such a way that we can modify the tension to increase or decrase the heat, other than with voltage).

Am on my way to be succeeded in it,
Thanks for the suggestion...//MEROG

Using a Battery as fixed voltage source is not advisable .The temperature of the cutting wire is regulated by varying the applied voltage to the bow.

Rao

tension has nothing to do with the wire heat. Tension is to prevent the wire from sagging.

Rao

Quote from: Rao on May 26, 2009, 10:15:20 AM
Using a Battery as fixed voltage source is not advisable .The temperature of the cutting wire is regulated by varying the applied voltage to the bow.

Rao

Yes, I too agree with Mr. Rao,

The temp. can be regulated by using the DIMER SWITCH, which is connected to the adapter, which can supply a regulated voltage! It's safe too!

Mr. Rao, tension is nothing to do with the temp? Then can you tell any possible reason why I failed when I connected 12V adapter to a guitar steel string, which is bent in U-shape (to fecilitate handy cutting)?

Awaiting reply...//MEROG
MEROG

try using a voltage transformer which has amp adjustment and keep increasing the amps until you get the right amount of heat. increase amps slowly

Here is a simple Hot Wire Foam Cutter