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May 04, 2020, 03:09 PM
Ich Fliege
goebelmj's Avatar
Quote:
Originally Posted by Michael763
I like your wing technique. I will have to find a test subject. What is the red and white plane that is in the pictures? If there are plans I have the MPF to test with.
Both are scratch built designs. The swept wing is my design and the other is built from plans I drew up after seeing the Drak (minus the forward swept wing).

Both designs are a result of searching for the most practical fuselage design for an FPV platform. The KFm3 wing design is a proven winner. Stacking gear inside a fuselage is taking some thought.

The swept wing fuselage has lots of room but is annoyingly inconvenient when trying to access the gear inside. The Drak wing fuselage was a direct result of this but Iím finding it can be improved upon as well.

I have plans for the swept wing but they are very basic, mainly just panel templates. You would have to put some thought into turning the plan into a functional flyer. I donít do detailed plans with instructions anymore. Sorry.

MikeyG
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May 04, 2020, 08:43 PM
Registered User
Gregco10's Avatar
[QUOTE=headlessagain;44429219]Another way of forming the leading edge is to use stock blasa le.

Hey Headless, I tried a flat strip of balsa stiffener strip on top of a foam wing recently. I urethaned the balsa parts before gluing them on. The plane came out nice and flew well. I let it sit for a while and the wings warped down. Any ideas on preventing this? Balsa and foam are a great combo imo but this would be a dealbreaker if it keeps happening.
May 05, 2020, 12:27 AM
It seemed like a good idea!!!!
Hookit's Avatar
[QUOTE=Gregco10;44435433]
Quote:
Originally Posted by headlessagain
Another way of forming the leading edge is to use stock blasa le.

Hey Headless, I tried a flat strip of balsa stiffener strip on top of a foam wing recently. I urethaned the balsa parts before gluing them on. The plane came out nice and flew well. I let it sit for a while and the wings warped down. Any ideas on preventing this? Balsa and foam are a great combo imo but this would be a dealbreaker if it keeps happening.
I use the same technique as Headless by using balsa leading edge stock on dozens of wings (KF2, 3 and 4).

The only time they have warped Is after a full throttle arrival .

LE is a lot more rigid than spar material, probably due to its shape.
May 05, 2020, 09:21 AM
Registered User
Quote:
Originally Posted by goebelmj
Both are scratch built designs. The swept wing is my design and the other is built from plans I drew up after seeing the Drak (minus the forward swept wing).
Both designs are a result of searching for the most practical fuselage design for an FPV platform. The KFm3 wing design is a proven winner. Stacking gear inside a fuselage is taking some thought.
The swept wing fuselage has lots of room but is annoyingly inconvenient when trying to access the gear inside. The Drak wing fuselage was a direct result of this but Iím finding it can be improved upon as well.
I have plans for the swept wing but they are very basic, mainly just panel templates. You would have to put some thought into turning the plan into a functional flyer. I donít do detailed plans with instructions anymore. Sorry.
MikeyG
Sure, templates are fine, as long as you donít mind. (I like the Drak style.) I can put the templates into SketchUp and figure things out from there. I can create a DXF and G-code from there. Especially since I have extra time on my hands during this unique time.
May 05, 2020, 07:49 PM
Registered User
Gregco10's Avatar
I use the same technique as Headless by using balsa leading edge stock on dozens of wings (KF2, 3 and 4).

The only time they have warped Is after a full throttle arrival .

LE is a lot more rigid than spar material, probably due to its shape.[/QUOTE]

Any sealing or paint? Or just bare wood
May 06, 2020, 11:32 AM
It seemed like a good idea!!!!
Hookit's Avatar
Quote:
Originally Posted by Gregco10
I use the same technique as Headless by using balsa leading edge stock on dozens of wings (KF2, 3 and 4).

The only time they have warped Is after a full throttle arrival .

LE is a lot more rigid than spar material, probably due to its shape.
Any sealing or paint? Or just bare wood[/QUOTE]

I virtually always use laminating film over the entire wing which usually makes for a pretty ridgid wing without additional spars.
May 06, 2020, 11:55 AM
Reap the wild wind
headlessagain's Avatar
Gregco10, I usually embed a 6mm x 1mm carbon flat in the bottom part of the wing just infront of the KFm step. If you are using a KFm-3 then I glue it to the front of the upright foam spar.
I usually cover my wings with coloured packing tape. Only slope EPP models tend to get the laminating film but they have a much harder life
May 10, 2020, 10:31 PM
2.4GHz systems, Electrics, FPV
I have searched here but cannot find a KFM airfoil data/coordinate file in DAT or the COR formats....???? Having searched high and low on Google but no one seems to have generated a file for the various standard KFM airfoils in dat or cor formats...??? Per the original graphic shown here earlier of the about 6-8 versions..with or without a Phillips entry on the LE...

I recently bought a licence for the Winghelper wing design programme and would like to try out the various KFM airfoils etc....Thanks for any info Laurie
Last edited by Laurence Carroll; May 10, 2020 at 10:41 PM. Reason: More info on my searches online, Phillips LE
May 10, 2020, 11:56 PM
looking up, down under
scruffy1's Avatar
Quote:
Originally Posted by Laurence Carroll
I have searched here but cannot find a KFM airfoil data/coordinate file in DAT or the COR formats....???? Having searched high and low on Google but no one seems to have generated a file for the various standard KFM airfoils in dat or cor formats...??? Per the original graphic shown here earlier of the about 6-8 versions..with or without a Phillips entry on the LE...

I recently bought a licence for the Winghelper wing design programme and would like to try out the various KFM airfoils etc....Thanks for any info Laurie
unlike most airfoil families, kfm are largely "as you like it"

perhaps the real interest here would be if you could gain meaningful data out of comparisons of some home grown variations, but from a quick google it appears that program is for design, not aerodynamic analysis
May 24, 2020, 04:39 AM
just Some Useless Geek
Hey, Andy! I just now saw that Skyray. Verrrry nice. I built a profile Skyray as one of my first foamies back in about 2008 or so. I had the balance so far off the plane flew better inverted than right side up. Crashed it so much it became mush.

After seeing yours I'm driven to maybe build another one. I really like the F4D as a wing plan, and making another one in profile -- properly -- would probby exorcise some demons that have hung around for a decade. We'll see.

(Of course it would have to be a KFm4.)
May 24, 2020, 05:10 AM
Reap the wild wind
headlessagain's Avatar
Quote:
Originally Posted by A Useless Geek
Hey, Andy! I just now saw that Skyray. Verrrry nice. .....
Thanks. It was a sweet flyer even though I built it heavy. The fuse was a double thickness of foam with correx either side so was very tough. It did mean that the battery slot wasn't a weak point
Andy
May 24, 2020, 08:31 AM
Registered User
davereap's Avatar
latest KFm2.. the superfly shape with twin motors using differential thrust..
Goldguys idea calling it an UltraFly
May 24, 2020, 09:03 AM
Jack
jackerbes's Avatar
Thread OP
Quote:
Originally Posted by Laurence Carroll
I have searched here but cannot find a KFM airfoil data/coordinate file in DAT or the COR formats....???? Having searched high and low on Google but no one seems to have generated a file for the various standard KFM airfoils in dat or cor formats...??? Per the original grer aphic shown here earlier of the about 6-8 versions..with or without a Phillips entry on the LE...

I recently bought a licence for the Winghelper wing design programme and would like to try out the various KFM airfoils etc....Thanks for any info Laurie
There is somewhat of a technical document about KF wings here in a *.pdf document in post #2 of this thread:

https://www.rcgroups.com/forums/show...8&d=1531002434

To browse the attachments in the thread go to the first page and choose to browse all the attachments from the Thread Tools menu at the upper right of the page...

Jack
May 24, 2020, 09:22 AM
Jack
jackerbes's Avatar
Thread OP
Here is another way to make the full length tape hinge, it is the same way that Dave Reap make it but by adding a layer of thin cardboard as a spacer between the layers temporarily when you do the first piece of tape it leaves a narrow line of exposed tape when the elevator is folded back. And then when you add the top layer of tape you can press the two pieces of tape into contact with each other and have a very narrow but strong tape to tape hinge line.

I used to use a propeller tip to chase down the hinge line and get the two layers of tape into contact.

If there is a better way to make a hinge line on a foamie I don't recall what it would be...

Jack
May 24, 2020, 06:52 PM
Registered User
Dickeroo's Avatar
Quote:
Originally Posted by davereap
latest KFm2.. the superfly shape with twin motors using differential thrust..
Goldguys idea calling it an UltraFly
Dave.... Did you ever get the KFm3 into the sky?


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