Thread Tools
This thread is privately moderated by maguro, who may elect to delete unwanted replies.
Mar 25, 2020, 03:27 PM
Registered User
Hi
I am looking for some polars for these kfm profiles (120K<Re<400K). I have done some searches but no luck so far.
Thanks
Sign up now
to remove ads between posts
Mar 26, 2020, 01:52 AM
Build straight - Fly twisty
Whiskers's Avatar
Quote:
Originally Posted by Hunterixus
Hi
I am looking for some polars for these kfm profiles (120K<Re<400K). I have done some searches but no luck so far.
Thanks
Scarce as unicorns
Apr 29, 2020, 12:20 PM
Registered User
I have a GLUE question!
When laminating sheets of foam board w/ paper on to make the KF layers, what's the best glue?
Hot melt is hard to spread over large surfaces in a thin layer.
Foam Tack works, but it's pricey for large areas.
I've used Gorilla Glue, but again, it's fairly thick and hard to spread thinly. And it "foams" on curing.
Can I just use something like Elmer's glue or the yellow carpenter's glue? That can be water-diluted to thin out if necessary.

Anyone tried this?

Steve
Apr 29, 2020, 03:08 PM
Jack
jackerbes's Avatar
If you have some scraps you can always glue a couple of pieces together, let it set up (overnight is best) and then try to pull them apart to test the adhesion.

I like to use the clear Gorilla White glue for bare foam to bare foam bonds. I dribble streams, spread it into foam in a thin and even layer with a flexible plastic scraper made from a flexible plastic can lid, then spray one of the two pieces of foam with a fne mist of water from a plant sprayer (to make the Gorilla glue foam) and then lay the two pieces together, lay a board on them to spread the weight evenly, and then add some heavier weight to hold it all together.

When I am using colored package sealing tape to add color and strengthen foam wings I spray a fine mist of 3M 77 aerosol adhesive on the bare foam (paper or plastic removed), give it a minute or so to dry, and then apply the tape. The bod between the tape and glue is ver good and the tape cannot be removed without damaging the foam for the most part.

If you find a house or generic brand of aerosol adhesive near the 3M 77 at about half the cost, it will work as well as the 3M stuff in my opinion.

Here is a wing build that shows most of the materials I use and how I use them:

** Blu Baby 33" KFm3P Polyhedral Tip Wing Build ** - https://www.rcgroups.com/forums/showthread.php?1474665

Jack
Apr 29, 2020, 03:28 PM
flyin' fool
goldguy's Avatar
I found with GG clear if you leave the water out of the equation it doesn't foam up excessively.
Apr 29, 2020, 11:29 PM
Registered User
Michael V's Avatar
Quote:
Originally Posted by Flyboy Steve
I have a GLUE question!
When laminating sheets of foam board w/ paper on to make the KF layers, what's the best glue?
Hot melt is hard to spread over large surfaces in a thin layer.
Foam Tack works, but it's pricey for large areas.
I've used Gorilla Glue, but again, it's fairly thick and hard to spread thinly. And it "foams" on curing.
Can I just use something like Elmer's glue or the yellow carpenter's glue? That can be water-diluted to thin out if necessary.

Anyone tried this?

Steve
I use WBPU (like varnish) as glue for laminating, works great, but it needs to cure for a while (maybe 24h or more)
Apr 30, 2020, 12:18 AM
Registered User
I read somewhere that regular house water based house paint primer can be used as a ‘glue’ to laminate foam sheets. I tried it and it works! You can even reposition the foam sheets when initially stacking them too!
Apr 30, 2020, 03:28 PM
Registered User
Lots of good suggestions to try! I'll let you know what seems to work best....

Thanks!
Apr 30, 2020, 04:14 PM
Jack
jackerbes's Avatar
Quote:
Originally Posted by goldguy
I found with GG clear if you leave the water out of the equation it doesn't foam up excessively.
I think it is the foaming action on the bare foam parts that gets the best penetration and bond between the parts. The foam can "lift" and move the parts away from each other and that is why I lay that flat board on top of the upper part and weight it down well.

But, as always, experiences can vary with different foams, different coatings on the foams, and even the way you hold you mouth as you work!

Jack
May 13, 2020, 04:43 PM
Registered User
Hi Everyone

I've just finished building a couple of EzFly foamies and asked the following question

"Each build that involves the KF step, under or over the wing, the "Step" (As I'll refer to it from now) is the same thickness as the main wing ie EzFly 9mm wing with 9mm Step. Do both have to be the same thickness? Or is this a builders convenience thing? I ask as I was wondering what would be the effect if I made the Step out of 3mm or 5mm does the "Effect" (Just say stability or easier handling etc) dependent on the Step having to be the same thickness, is the effect reduced by making the Step of a thinner material. The original EzFly PDF didn't have the KF airfoil to begin with did it, has it, made a big difference?

Ta in advance as usual.

Cheers, Tony"

Thinking that this is the airfoil page perhaps someone on here can help please. Granted I haven't read every post so the answer may lie within, however it's worth asking.
May 14, 2020, 09:42 AM
Jack
jackerbes's Avatar
A 9mm high step would be a inordinately high step. Most builds are with foam that is 3mm to 6mm thick and the step height is about the same as the thickness of the foam.

This image is from the first page of this thread and gives some examples. The KF building thread also has many examples in it...

Jack
May 14, 2020, 12:20 PM
Registered User
Thanks for answering. The 9mm is the actual size on the EzFly, I suspect it was done, it's not the only example, for convenience. I had seen the pic you posted before what I didn't take note of, which I should have, is the thickness as a % .

Tony
May 16, 2020, 09:04 AM
Jack
jackerbes's Avatar
Don't be afraid to experiment, almost anything will work and you never know when you will discover something that works better with your particular combination of motor, Kv, battery voltage, and prop.

An example what worked best for me was the KF wing with a flat center section and polyhedral tips. That worked well, as far as stability and control, with or without ailerons and for different types of planes too.

** Blu Baby 33" KFm3P Polyhedral Tip Wing Build ** - https://www.rcgroups.com/forums/showthread.php?1474665

The "KFm3P" nomenclature was my idea, just to identify it from the others. The polyhedral tips also worked well on a KFm4 wing (steps on the top and bottom).

Jack
Aug 02, 2020, 02:05 PM
Registered User
Dickeroo's Avatar

Time Flies


Mario Gentile sent me this video about turbulent flow and aerodynamics.

Turbulent Flow:
Turbulent Flow is MORE Awesome Than Laminar Flow (18 min 32 sec)


KFm Airfoil on The David Letterman Show back in 1984:
Richard Kline, Paper Airplane Designer, on Late Night, March 15, 1984 (7 min 57 sec)
Sep 12, 2020, 09:35 PM
Slow Flight

Conversion to KFM -How it is done- Beginner questions


Hi All ,
I want to build a small ( 95mm) sabage bobber . Wood structure ( 1/8 x 1/8) and foam Ffm 2 wing.

I want the wing with large ailerons like the Timber X 1.2 (120cm wing spam) or like the Tottle from Thomas Buchwald (60cm wing spam).

Why :
I do not want to build a standard wood wing to later cover it with Foil. I want something easy to build. And with stol characteritics of the Trottle. I know that Flufmodel magazine with publish some Stol planes in about 8 weeks .....just do not want to wait that much.


Questions:
1. I know Kfm 2 does not have same lift as a regular airfoil , but for the conversion should i use the same wing core it shoud be modified?
2. Is the 50% step measured including the ailerons or without includind the ailerons?
3. The Trottle has flaps of 25% of wing core , timber x 1.2 has a flaps of 40% of wing core. Is there any rule or good practize or recommendation for the size of the flaps using a Kfm 2 airfoil?

Any advice is appreciated,

Thanks
Alex


Quick Reply
Message:

Thread Tools

Similar Threads
Category Thread Thread Starter Forum Replies Last Post
Discussion ** Kline-Fogleman (KFm) Airfoils - Building/Flying Discussion ** jackerbes Foamies (Scratchbuilt) 10497 Today 05:38 AM
Discussion ** Kline-Fogleman Airfoiled Flying Wing ** Tony65x55 Foamies (Scratchbuilt) 3960 Jul 20, 2018 06:01 AM
Cool Here is my KFm-5 DLG GLider (Kline-Fogleman) dougmontgomery Foamies (Scratchbuilt) 151 Apr 21, 2014 09:08 AM
Video Kline Fogleman Airfoil on a flying wing Tony65x55 Electric Plane Talk 3 Jan 30, 2009 08:37 PM
Idea Per Dick Kline, Kline-Fogleman test dougmontgomery Hand Launch 49 Apr 13, 2007 02:13 AM