RC India

Hi guys!!!!

After badly crashing my 30” Yak 54 last weekend I was getting little impatient about making new Yak 54. During this period also worked on F-15, will complete it after Diwali once I am back from my native!!!!
But about new yak this time I decided to make symmetrical aerofoil instead of flat, profile one!!!! I think it would be rather stable than profile!!!! Lets see.

Will be using 2213, 1000Kv from HK with 3s lipo may be around 1000mAh. Currently I am using this motor on my 60” wing Wind Spirit glider, which I converted to brushless!!!

To make aerofoil symmetrical had few ideas, which I saw on different forums, like cutting symmetrical aerofoil using hotwire and all that but it were not partially possible for me.
Few days back had word with Amar, who is also dedicated foam builder from Pune. He suggested to use 3 mm foam, bend around 1” thick spar running from tip to tip, I liked this idea and easy for me to do it. Also had discussion with Angad and Sandeep, told to use clear tape on one side and use ball pen to mark lines on opposite side so that it will be easy to bend the foam. Initially I was not very much convinced so I give it a try on small piece and results were not satisfactory as bended curve was not that smooth!!!! So instead of ball pen I decided to use roller to press the foam and bend it. So the best roller is “Roti bananeka Belan”. Further discuss it with Angad and got some valuable inputs!!!!!

And finally on Saturday afternoon and today I was at least able to complete half wing with perfectly symmetrical aerofoil. For other half, frame is ready, all I need to cover it with 3 mm foam. Had to stop as  I ran out of Evotite, will complete it after Diwali!!!

Dimensions of this yak is almost same as my previous 30” yak, only difference is symmetrical aerofoil wing.
I used 8mm foam to create wing frame, and covered it with 3 mm biofoam. I used 2” clear tape, to help in bending the foam.

Pls find few pictures

some more

Looking good !!!    :thumbsup:

Great Job, :thumbsup:

 What glue are you using ??

thanks buzz, bmanoj!!!

i am using Evotite super glue, it is foam safe!!!

Wing is looking great...your work is very fine..!
Can you provide the link of motor you are using..?

thanks spitfire!!!

wil be using following motor, i think will be over powered, but it is with me, so instead of buying new one will go with this one!!!

http://www.hobbycity.com/hobbycity/store/uh_viewItem.asp?idProduct=5689

Thats great..!
Are you using any plan for this build...? Also for yak 25" mentioned in your signature have you used any plan..?

u can check my earlier post for 30":
http://www.rcindia.org/electric-planes/mini-yak-54-made-from-biofoam!!/

i used same plan and reduced it to 25"

Thanks for link...!
Best luck for your build...!

Amazing !!  :bow:

1 . What foam is this ? and how is that it has been bent like that ?
Is possible try to post a video of how to bend foam ?
This is the first time I'm seeing this type of wing (foam + hollow + bend).
Usually the type I have seen for foam is a solid etched out of hot wire..

2. In your earlier Mini Biofoam YAK, how have you stuck the radium sticker ?

All the best and keep us posted.  :salute:

Can the OP respond to this question about bending foam ?  We were discussing this today with someone, and I was wondering what are the common techniques for bending foam :)

that is a neat airfoil U got there buddy... {:)}

Whats the a.u.w. of the plane?? the motor u mentioned may be an overkill ! :headscratch:

Pl do keep us posted abt the progress ahead & all the best for it :thumbsup:

Ops!!!!! I missed it !!!!

it is very easy to bend!!! no rocket science!!!

I used 3 & 8mm Biofoam to make this airfoil!!! Unfortunately I don’t have any video for this

1st I made frame (as shown in 1st 4pic) using 8mm biofoam, reinforce it with 5 mm hollow CF tube for strength!!! Then took 3mm biofoam sheet and covered leading edge, where bend is maximum, with 2" transparent plastic tape (available in any stationery shop). this is to ensure that 3mm biofoam will not break while bending. now after applying tape i used roller to apply pressure on the other side, this will help me in bending the sheet. keep in mind that roller axis should be in line with leading edge.
if required, Angad also advised me to use hairdryer to slightly warm the sheet, which will further help in bending.

once bended, i used foamsafe CA glue to join it!!! here u have to have foamsafe super glue,  cause u have to practically keep on holding this airfoil till 3mm sheet is joined to the frame, so using other slow or 5 min epoxy is very difficult!!

instead of bending one can also cut both side in 3 mm sheet and use simple 1"or 2", 8 mm biofoam spar and stick these pieces above and below to create aerofoil shape.
stick spar on around 30% from the leading edge, and stick both pieces on upper and lower sides. once secured, stick leading and trailing edge, and ur done!!!! this is comparatively very easy to make, rather than bending!!!!

Unfortunately last weekend I did maiden……. And did something stupid and had nose dive, crashed. Nose is completely gone, airfoil is slightly damaged, but whole thing is repairable, but will need considerable time!!!

Mean while I am planning to complete my new SU27, which is cut and ready to be joined together!!!

Smart... :)