RC India

Hello everyone
In one of my profile jet projects due to weight issues am being compelled to use the following aerofoil...
Please comment on what effects it will have on flying characteristics

Sirji why not use a kfm4? Will be similar in weight to what you have made. Even a kf2 should work.

Flying characteristics may not be affected much but strength yes and in a big way. The creation of 2 notch areas would result in accumalation of stress and failure at these points.

Providing a gradual curve at these sharp bends may help.

@Rcniel no kfm4 is a bi symmetrical aerofoil but mine cannot be changed am stuck with the above mentioned aerofoil
@allthatido strength is not a issue as its reinforced..

I said  think The undercamber is gonna change the flying characteristics...  In what way am not sure

Cannot be changed? Has the wing with this airfoil already been built?

the undercamber should be gradual, this airfoil has sharp edges. And undercambered wings on jets is very different from what ive seen.

Is it really airfoil ? By shaping it in curve may help in streamline flow ..
Corners may produce a lot of turbulence .
The turning of the air in the vicinity of the airfoil creates curved streamlines which results in lower pressure on one side and higher pressure on the other.

@Rcniel21 A flat wing is ready ...  But now my wing loading is high ( coz am experimenting with a new material)  so I need to cut out the center bulk to reduce weight  and cover the upper portion of the cut part and that will turn out to be the above aerofoil..
@aditya that's just a schematic representation

You can cover the bottom surface with some other lighter material maybe?

Make a new wing. As allthathedoes said you have stress concentration points. The heavy undercamber with the unevenness will cause more lift, but with unpredictable turbulence

Rai sir the model is already made... And wing cannot be changed...  If I smoothen the undercamber curvature will it help?

Lol, could not have expected this..ha ha  ;D

@Docnayeem
Can you post a pic of the wing. The chain is as strong as the weakest link. And your weak links are the notches here. Even if you cover the wing, you cant stop stress from travelling to the notch and breaking it. Trust me , I am a mechanical engineer like Sanjay Ji, just not from IIT..he he  :P

To lighten the wing ribs, you can cut slots in the ribs instead of cutting like this.
Should be somewhere in this website: http://www.airfieldmodels.com/ (http://www.airfieldmodels.com/)
Just my two cents...
Ashok.P

@docnayeem sir,
Refrained from responding as the pic you posted is not exactly an aerofoil at all...
Unable to guess why you have such a section at all (there are other ways of reducing weight, like cutting holes)
Best solution seems to be to put a spar, ribs and covering from below...

What is WS? Maybe you can cut LE and TE sections leaving only the flat plate, then make kfm2?

Iyer sir is right putting in ribs and covering looks like the only option  option but could add weight to your plane.

Does the jet fly with this configuration?

Thanks Ashok sir

Iyer Sir I totally understand your dilemma my representation was probably wrong...  Will post a pic and this should put things in a better prospective

Schematic diagram of the model

Dotted lines depict the part of the wing I plan to cut ( to reduce weight)

And then the top surface will be covered with 2mm coro...  And that's how that aerofoil (if I can call it aerofoil)  will look like...
I hope am able to put things across the table ? *

You can use much lighter depron fot that job

@docnayeem,
Sir,
If you have not yet cut into the material, you can consider the following:
1. Sand to a reasonably streamlined aerofoil type shape
2. Mark from tip to tip, about 30% from LE and about 15% from TE.
3. In the intervening 55%, cut circular holes to reduce weight.
4. Cover with iron on film or laminating sheet.