Hello everyone,

I am trying to build KFM3 airfoil. I made the wing. Recommended thickness of the wing is 9-12% of chord length.

I made a mistake and my wings thickness comes out to be 14%.

The question is: Will it work?

Thanks.

Swapnil

Yes it will work no doubt.

14% will only induce more drag & Lift.
Plan for a little more powerful engine ( motor) than recommended. There may be tweaking required for down thrust.

Thank you so much.

Yes.
The plane did fly. I am so happy as it was my first build and first flight.
Unfortunately after reaching certain height it plunged to the ground so hard that I'll have to build new one.

"Unfortunately after reaching certain height it plunged to the ground so hard that I'll have to build new one."

This is very normal in this hobby.

A few leave because of this and a few aim to make better next time.

Yes. Thanks for moral support.

This time i will go with pusher configuration.

Pusher planes end up tail heavy... Incorporate bigger nose fuse to counter CG.

Yes I will. Thanks for the tip. Few more tips are welcome.

Quote from: swapnilnimbalkar on December 14, 2016, 10:22:06 AM
I made a mistake and my wings thickness comes out to be 14%.

The question is: Will it work?

Swapnil

Swapnil......did you try it? any pics?

The plane did not fly. I crashed it even before taking off.

Can you tell the weight of model, motor spec, prop.

I have tried the same pusher model in coro sheets. It just hit the ground. I believe the motor angle need to be slightly up. This creates a upward moment I feel. Experts correct me if I am wrong.

Quote from: swapnilnimbalkar on January 10, 2017, 11:26:58 PM
The plane did not fly. I crashed it even before taking off.

swapnil...this can be frustrating...so here are some tips:
1. Do away with the ailerons and landing gear for your first plane - you can hand-launch.
2. Was the prop fixed in the correct direction? ( assuming you used a suitable/adequate motor)
3. How much throws did you set?
4. Did you do a glide test...to ensure the CG was right?
5. Can you simplify your Tail surfaces? Are the horns fixed 'correctly'?

...While it is possible to build and successfully fly your first plane ' all by yourself', there are several things that can't be covered here - do you know any other flyer in your area? This can be invaluable as what you really need is someone who can really be there to see what is happening.....unless you take the pain of shooting/uploading a video of the crash.

OR....start afresh and build a new plane.

If you can share the equipment and material you have access to....we could put together a plane that you can build in a day.

here's something you may like http://www.rcindia.org/electric-planes/pusher-trainer-for-beginners-bgnr/

Dont bother building a wing described in the thread....KFm 2 works just fine.

Thank you so much for the input.

As per my understanding the prop was fixed at suitable position with little bit of downthrust.

I did test glide with it. It did glide well. As far as throws are concerned I did not calculate it. Will do it n tell you.

Yes the horns are fixed correctly.

I will increase the wing span, currently it is 40". So I will add 6" on either side with little bit of dihedral. Total will be 52".

I am afraid of hand launch thats why i did the landing gear and all. Also adding landing gear corrected my CG.

Quote from: swapnilnimbalkar on January 12, 2017, 11:19:19 AM

I am afraid of hand launch thats why i did the landing gear and all. Also adding landing gear corrected my CG.

Even I had the same fear. let go off it. Just have a friend with you to launch it and you can fly it. I had a friend of mine with me most of the time.

Yes i will give it a try next time. Thank you.

Quote from: swapnilnimbalkar on January 12, 2017, 11:19:19 AM
Thank you so much for the input.

As per my understanding the prop was fixed at suitable position with little bit of downthrust.

I did test glide with it. It did glide well. As far as throws are concerned I did not calculate it. Will do it n tell you.

Yes the horns are fixed correctly.

I will increase the wing span, currently it is 40". So I will add 6" on either side with little bit of dihedral. Total will be 52".

I am afraid of hand launch thats why i did the landing gear and all. Also adding landing gear corrected my CG.

great! so you know the checklist.

your wing actually looks quite good....and I am sure the ailerons operate opposite direction. adding the tips is a good idea...the ideal wing planform for a first plane.

...can you describe the first flight ? is there any serious damage? including the total weight(AUW) helps in getting a better idea of the plane....

from what you say and looking at the pic, theres no reason for it not to have a decent flight...

good luck

Hey Hi.

The wing is actually quite good with the load bearing capacity. I put a dictionary at middle of the wing and held it near tips i mean one tip in my hand and other one was held by my brother.

It did not deteriorate at all, neither bent. The dictionary weight about 1100 gms. I think it has more load bearing capacity but its worthless to check as my plane AUW was 770gms including wing. The wing is 180 gms in weight.

Yes the ailerons move in opposite direction.

The nose of the plane is very low density thermocol i.e. crush zone. Its about 3 to 4  inches in height and width according to the profile of the plane and tapered towards front.

About the first flight:
I put it on the runway. Which is isolated road on a big ground you can say cul de sac.
Gave throttle, it started moving, whole time my thumb was tx for full up elevetor it didnt fly just veered in right direction towards some big stones.
Second try was same but this time it veered to the left and hit a stone so hard that the front thermocol (i.e. crush zone) was totally destroyed, saving my plane. Just the motor mount which was secured with two sided tape came out of its position.

By the time lot of kids had gathered around me, so i left the place along with my friend, thinking it might hurt someone. You know kids might just put their finger to check how fast the propeller is spinning.

May be this upcoming Sunday or next one I will give it a try.

Thank you.
Swapnil Nimbalkar

Hello everyone.

The hand launch method did work. It flew.
Unfortunately I did not capture any video.

Thank you everyone who helped me.