** Kline-Fogleman (KFm) Airfoils - Building/Flying Discussion ** - Page 317 - RC Groups
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This thread is privately moderated by jackerbes, who may elect to delete unwanted replies.
Sep 23, 2012, 12:43 PM
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Originally Posted by davereap
...What KFm4 would do for your model...do away with the CF spars, but make a stronger wing , make a thicker slower wing...do you want any of that, is it needed?...I wouldnt bother with extra work when what youve already got is that nice...
That's what I was thinking. It flies so well as is, and the wings are super-strong already, with heavy tape reinforcement, 6mm CF spars, and 1.8mm CF rod "guy wires" very securely anchored to the wings. I'll post another reply with the tape pattern drawings and a few photos of the construction details that make it the stiff brick that it is.

Originally Posted by davereap
.....but where's the build thread?
See the two debris pile photos below. That's what's burning up every available minute of my time right now. We just bought another house that we have to be in by October 15, and it's turned out to be a true fixer-upper. We discover new deficiencies that must be addressed almost every day.

Worse than that, the build thread has taken on a life of its own (as usually happens with most all of my projects), and has grown into a completely out-of-hand behemoth that will include five videos, at least 24 separate posts, at least ninety photos, three different versions of the plans, many other drawings, and lengthy dissertations on things such as materials of construction, transmitter programming, and motor selection. The motor section alone is such a classic example of obsessive-compulsive fixated behavior it's downright embarrassing.

If I get the damned thing done by New Year's Day it'll be a miracle.

Thanks for the reply. You've confirmed what I thought would be the case in this particular application.
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Sep 23, 2012, 06:08 PM
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Dickeroo's Avatar

Another outstanding FPV video.

Here is a video from FPVRC and probably a first where you see the FPV plane following, then in front of car as it travels along a country road. Some very interesting visual concepts here.

FPV Vacation 2012 (4 min 52 sec)
Sep 24, 2012, 04:03 AM
Registered User
davereap's Avatar
You all know I am a KF fanatic and although it does make for great flying models, It can add too much extra stability, so for 3D performance it might not always improve things..

Its a subjective issue as to how you like your models to fly.. the Regal (by Kaos2) mentioned earlier is a good flying model, but with both wings KFm2 it has very much a lifting rather than neutral wing setup..
I did think after I flew it, that it might be more neutral as a KFm4 or even with the top wing with a top step and the bottom wing with a bottom step..

All you can do is try the options..or not bother and wait for some one else to modify your design... you know what most modelers are like, lol, eventually they always mess with any good model in the hope it gets even better
Sep 24, 2012, 09:25 AM
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Dickeroo's Avatar
The coastline of Norway on a bright and beautiful day.
Trond is flying a KFm2. He is still working on his KFm4 flying wing.
It will be interesting to see if there is much difference in the way these two wings perform.

FPV49 v2 over Ulvøyna (11 min 38 sec)
Sep 24, 2012, 03:05 PM
Thomas B.'s Avatar
Great video!
Sep 25, 2012, 02:20 AM
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davereap's Avatar
something off topic that I bought and was very very good

I have had this link reported on a different thread and recieved penalty points .... its against forum rules to have a link to anything that may encorage use of pirated software

Not my intention.... as the usb gadget was to be used as a spare to replace the dongle on my reflex XTR simulator..which it does well
Last edited by davereap; Sep 26, 2012 at 04:13 AM.
Sep 25, 2012, 05:57 AM
jackerbes's Avatar
Nice find, Dave!

and here is the Colonial eBay version of it:


Sep 28, 2012, 07:25 AM
Registered User
davereap's Avatar
hobyking sell the gadget and they also do a wireless version that you use with your own reciever
Sep 30, 2012, 04:33 PM
Thomas B.'s Avatar

Semff Zero

The Kfm 2 is a great airfoil even for aerobatics; nearly neutral inverted and knive edge flight; the semff combat planes prove it:
Zero (1 min 0 sec)
Sep 30, 2012, 05:31 PM
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Dickeroo's Avatar

Your flying builds and skills help to show the characteristics of the KFm2 airfoil.
I thank you for that.

~ Dick
Oct 01, 2012, 09:51 AM
Registered User

KF2 Quandry

Hi all, looking at some vids. of models withKF2 profile I notice that some are only folded over flat to top wing. Is this correct or do they have a minimum step which may or may not affect flying quality. ? Cheers.
Oct 01, 2012, 10:51 AM
flyin' fool
goldguy's Avatar
I'm a KF2 fan too. I've never found it lacking when it comes to aerobatics. The secret to success is a proper leading edge profile more than the step height, although there are rules about that.

Most of my KF2 experience is with aerobatic slope flying where there's no motor to mask it's performance. And yes, it's works right side up, upside down and sideways.
Oct 01, 2012, 11:49 AM
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davereap's Avatar
Goldguy just loves his Revert sloper...

Two layers simply laminated flat together or folded flat are fine.. the step depth affects how well the step works, but we mostly use layers between 3 - 9mm..
and all work ok ... My preference for simple KFm2's is a 6mm step, which is fine on spans up to 36.. you might want to go a bit deeper on bigger spans, but this is not essential..
On bigger span KFm2 wings I sometimes stick some 1x1/4 balsa under the step to go up to 12 mm deep..The balsa then makes for a good spar and the CF rod/tube can be left out

Remember there are target thicknesses for total wing depth ratio to chord and the thickness of the layers and step depths build up a wing to the total thickness.. so we juggle to get the numbers reasonable...
Its not an exact science and mostly it all works well..

As a rule, if you go by the plans for any particular build it will be fine
Last edited by davereap; Oct 01, 2012 at 11:54 AM.
Oct 01, 2012, 05:29 PM
Registered User
Thanks a lot gold guy. Cheers
For Dave, Thinking of putting 6mm step on 6mm Depron Night Crow (delta shape pusher). have read it will improve flying quality. ? Cheers
Oct 01, 2012, 05:59 PM
Reap the wild wind
headlessagain's Avatar
I would go for a 3mm KFm-4 myself.

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