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KFm4 wing

teflyer

Full Circle
#1
Perhaps have a show on a small, 24", KFm4 wing and see how that performs. Also maybe make the same wing, but with a symmetric airfoil, such as the NACA 0015, and compare the performance. Also at the same time show how to do a setup for a small RC plane, what servos to use, recommended battery, and such.
 

earthsciteach

Moderator
Moderator
#2
I like the idea, TX. It would be interesting to see, given all other items equal, how the two different airfoils would compare in performance. I need to get back on my wing scratch build. I keep getting distracted by crash repairs and all the other little projects I start and don't complete due to ADD.
 

colorex

Rotor Riot!
Mentor
#3
I think that it's a bit hard to determine such differences on a small wing like that, but other than that, it would be cool to try!
 

teflyer

Full Circle
#4
Probably so. I was just looking at Otto Dieffenbach's 50% KFm4 Zephyr wing and it seems to perform similarly to the real Zephyr. and one of my hopes for a future project once I actually get some flights is flying a small flying wing that can handle high winds that we have down here or up here :p.
 

earthsciteach

Moderator
Moderator
#5
Tex-go to your local hardware store and buy a bundle of fan fold foam. You can build a pile of small flying wings from one $35 bundle. Hang a 1300kv motor on the back and rip up the sky!
 

teflyer

Full Circle
#6
Thanks for the advice, earthsciteach! However, I already have about $50 worth of dollar tree foam that I am using. Also I am a complete newbie at flying. I have had 0 flights (Controlled take off and landing) and about 20 crashes. I have built a plane I hope will be a good trainer. If you want to see it, I can take pictures.

I have tried flying wings before and love how they perform and how durable they are, but they are too acrobatic for me. My plan is to make some simple DLGs and see what happens. In my opinion, gliding for fun about 5mph is a lot easier than flying 20mph which is how I crashed all those planes. If you want to see the little chuck glider/DLG I made, I can also take pictures

Thanks though!
 

earthsciteach

Moderator
Moderator
#7
Post up what you have! We'd like to see what you've created!

Being new to flying, starting off with a scratchbuilt will have you chasing a lot of variables. If you can afford it, buy a Bixler ARF or kit. These things are a blast to fly and are really forgiving!
 

teflyer

Full Circle
#9
pictures! and to keep the thread sort of on topic, I included the KFm4 wing
SANY0194copy.JPG
SANY0195copy.JPG

oh, and yeah, I have been dealing with a lot of variables. Every non flight, I learned something new. It has been pretty great dsepite not really getting off the ground.
 

earthsciteach

Moderator
Moderator
#10
They both look really nice! What are the issues you have with the sailplane? It looks as though it would be a decent flyer. Perhaps the horz stabilizer is a bit too small. But, it really looks like a good plane!
 

earthsciteach

Moderator
Moderator
#12
No such thing as "too much power!" Just don't give it full throttle.

What battery are you using? Do you have any camber to the wing? Have you reinforced the wing with a spar?

What are the wind speeds? So full of questions. For the cost of dollar store foam, just go and fly it!
 
#13
I found out with my last plane, I tend to be throttle happy. :p
1300mAh 3S Turnigy Lipo
Yep, I have slight camber.
Bamboo skewers running the entire wing and bamboo skewer struts.
20mph winds
 

earthsciteach

Moderator
Moderator
#14
Ok, 20 mph is a bit much for a new flier. But, once you have a bit of experience, 20 mph is a blast with a plane like that!
Do you have any dihedral to the wing? That may make it really docile.
 

earthsciteach

Moderator
Moderator
#19
I'd go with a KFm3.5. Honestly, I don't know the difference. I'd go with a KF airfoil that is flat on top and doubled up on the bottom to 1/3 of the wing chord. Just put a big enough motor on it and it won't matter!
 

earthsciteach

Moderator
Moderator
#20
Oh, you said DLG. I have no experience here. But, a DLG is a very high performing sailplane. I'd expect that you would have to be in the world of carbon fiber everything. That would mean a "real" airfoil and extreme light weight to get any kind of duration from a 20" flying wing.