RC India

Well decided to build a bird that would act a a powered glider AND design the bird myself - even though I know very little of aerodynamics

To begin with, was wondering what would 'act' as a glider. So doing a bit of reading, from what I understood, was that the cubic loading needs to be low (i.e. less than 7 oz/cu ft). Further, the fulcrum for the control surfaces need to be far from the CG /NP.

With these two in directions, started of by listing the specs

Wing span = 50"
Chord = 7"
Length = 44"
Target AUW - not to exceed 700 gm

Now, in recent builds I have utilized a concept of using a thick block of EPP right behind the engine mount followed by a block of thermocol. These two provide excellent shock absorbing capabilities to the build. Since I am still learning to fly properly, this makes the plane a shade more resistant to crashes.

After cutting the fuse and sticking the pcs together

Looking good!

Applying the cover to the bottom of the fuse and attaching tail.

(photo of not a very good quality)

Attaching the EPP block on the nose.

reinforcing the surface for attaching wings

The 3mm x 10mm MDF strips were laser cut by VK of rcelectro

after applying the top layer of the fuse, the chambers to access the servo and battery

Now, for the belly and the landing gear.

I have made the UC detachable - here's how
The strut has been attached to a small piece of ply and then fit in the grove prepared in the fuse.

For Wing construction....

The basic Idea of wing is that this is a polyhedral with the flat portion being 30" and two raised portion of 10" each. The construction is as follows

not much clicked during wing building process.....

Finally putting it together....

I am not yet decided on the type of prop to use. I have pictured both using a normal and folding prop

OK, The finished product looks like this.


Now all that remains is to hand over to Divay next time I am on the field for the maiden.....

Final ALL up weight = 665gm, hence the calculated wing loading is around 6.2oz/cu ft.

motor 50gm 1400Kv, battery 3S 1000mAH, 18amp ESC

---------- end of construction --------

going good till now ,, waiting for the  further build {:)} .


this is going to be glow plane right ??

got it

Very beautiful glider {:)} i think you should use a folding prop but the one you have mounted on the motor is not good I've tried it on the same motor, no thrust and lots of power drain.
Good job on the build log, do post video of maiden if possible :thumbsup:

@SLS thanks for the encouragement. Any reference to the prop I should be using?

i'll be getting this (http://www.hobbyking.com/hobbyking/store/__13135__Folding_Propeller_Set_7_5_x_4_Inch_2pc_.html)in my next hk order, but this (http://www.rcbazaar.com/products/368-7-x-4-folding-propeller.aspx)on this (http://www.rcbazaar.com/products/103-folding-spinner-30-x-3-silver-colour.aspx)also looks good and is similar to what i'm using right now.

Nice build..  :thumbsup:
Me too making a glider, got much help from your build. will post build log soon.. My material is indian balsa..Me too at your stage. i.e. still learning  ;D

@vineet sir, cant get "glow plane"

@abhay1290. Thanks and look forward to your build log

glow plane = which uses fuel burn , like all engines , nitro plane

Hello Pankaj Sir,

Nice build.   {:)}

I was wondering how do you manage to cover the bottom of fuse with bio foam sheet  :headscratch: or it's because of less thickness? I have used 5mm and 10 mm bio foam it's not so flexible  8-)

Thanks,
-Vinayak

@VinayakR, thinner sheet is more flexible. That is why it was chosen. However, little bit of heat can form the 5mm into the desired shape as well.

Dihedral and ailerons generally don't go hand in hand. A di/poly hedral adds roll stability for a level flight, while ailerons makes the plane unstable by inducing a roll. So in effect both of these wing functionalities interfere with each other.

Ailerons are more effective on flat wing or a very minimal 1/2" or 1/4" dihedral wing.

couple of flights done (not by me :-), left it to experts Divay and Manish )yesterday on a reasonably windy day.

First the nose was way.... too heavy. so removed the extra weight added on the nose and pushed the battery a bit back and things stabilized.

Noticed another thing, on 50% throttle, its stable, but on full throttle, the bird starts climbing almost vertically ( with no elevator input). Maybe the thrust needs to point downwards ....

Can u post same more pics of the wing ,
all the views

Pankaj

1. see Image 0069, why do you need such a thick fuse aft of were the wing is attached to the fuse, it will increase wt and drag,

2. There are two very very basic principles that you must bear in mind while making a glider (a) Area Ruling (b) Reflex Camber

For both of these see my posts in the basic AD Thread and take the discussion to the that thread for larger good of posterity

3. Polyhedral has a lot of interference drag at the point of dihedral change, in fact if not made properly it can cause unnecessary roll and yaw. however it's lateral stability will be good and will behave very docile.

this build of yours should rather be a stepping stone something better in the future. :thumbsup:

Augustinev,

regarding point #1 above. If you mean thick as in width, then the thing is that at the point the wing is attached is about 3inch wide and the end of the tail is just the 2 sheets of 5mm sides that are glued together, to the taper is gradual. It would have been difficult to form the width as I did with the height. Hence the shape.
Beside what do you expect from a guy with no knowledge of AD setting out to design :D

Will read the AD thread again for point #2

Will try and capture a video and post on the flight characteristics
 

Regrding reply#26. Area ruling.
Read and re-read post #117 and #118 on the AD thread http://www.rcindia.org/rc-general-topics/basic-aerodynamics-for-rc-flying/100/.

Did not understand....

Did some webbing - located Whitcomb Area Rule - read it - still did not understand

However, did read one line that stated the research was related to transonic speed. If this is the case, then does it hold true for slow speed models as well???