Originally Posted by jackerbes

By the way, this thread is still open but inactive for all practical purposes. It was continued here and under a different name:

** Kline-Fogleman (KFm) Airfoils - Building/Flying Discussion ** - https://www.rcgroups.com/forums/show....php?t=1117276

Feel free to go there, drop in, and ask any KF wing building questions you might have. You'll be getting your answers from some of the most knowledgeable KF buillders on the forums...

Good luck with the project!

Jack

Thanks Jack. In order to give the kfm4 tip enough space between rear of the step and the leading edge of the control surface, I'm going to back the step down to 40% and see how it does.

Thanks again for the great advice,

Mike

Sorry, wrong thread

Originally Posted by goebelmj

Thanks Jack. In order to give the kfm4 tip enough space between rear of the step and the leading edge of the control surface, I'm going to back the step down to 40% and see how it does.

Thanks again for the great advice,

Mike

That will work and good luck with it! And James is trying to be helpful, not critical of you.

As long as this thread is not closed by the person that originated it (Tony65x55) and anyone is still subscribed to it you'll get replies here. But that KF building thread is much more likely to to get you the best replies...

Cheers,

Jack

Actually, I meant that I was on the wrong thread Jack. I was browsing this one because I am thinking about building a Zagnutz then I went to post a link to another thread but dropped it on this one by mistake. I couldn't find a way to delete the post so I edited the link and added the apology.

Can someone point me to a "How to....." about flying wing geometry, please? I want to build flying wings with KFm airfoils, but I dont know about the geometry!

Thanks in advance!

Originally Posted by SilbernerSurfer

Can someone point me to a "How to....." about flying wing geometry, please? I want to build flying wings with KFm airfoils, but I dont know about the geometry!

Thanks in advance!

This thread is pretty inactive but there is a lot of activity on this one:

** Kline-Fogleman (KFm) Airfoils - Building/Flying Discussion ** - https://www.rcgroups.com/forums/showthread.php?1117276

The first few posts in that thread have some info on the various KF airfoils. But for the most part there is no formal doctrine on the geometry of flying wings and nearly anything is worth trying. This thread is about the first thread about the Kline-Fogelman airfoil that appeared here and is probably what sparked the interest in the KF airfoil and started things.

If you go to any thread here in the top right of the page click on the link to Thread Tools > Show All Attachments in this Thread hyerlink you will see pages of thumbnail images from that thread. And that will let you see planes that might be of interest and drawings and plans for building it and other similar planes. You'll never go wrong or offend anyone by cashing in on the ideas that have worked for others. From the images you can click on them to see them in larger form and from there you can enter the thread at the post where the attachment is. When I do that I open new tabs to pursue the info.

Here is another thread that has a lot of info KF airfoil builds including some flying wings:

** Tony65x55 ** planes and plans. - https://www.rcgroups.com/forums/showthread.php?997484

And here are a couple of the wings that I know of and have built and they were both excellent flyers:

48" Divinity II Build - https://www.rcgroups.com/forums/showthread.php?1048425

Divinity, 42" KFm4 Slowfying wing. - https://www.rcgroups.com/forums/showthread.php?1023254

The KFm2 airfoil, with a single step on the bottom, as Tony65x55 used for this plane works very well as this thread indicates. But some of the airfoils that came along later flew even better and have other attractive traits. If I were going to choose one of the KFm airfoils as best for flying wings I might choose the KFm4 with steps top and bottom because it has proven itself in numerous builds and it also has a beautifully symmetrical shape to it.

Good luck with your project, and we would all enjoy seeing how it goes in a thread here...

Jack

And I forget to mention the Flying Wings subforum too, that can be a gold mine of info for building flying wings.

https://www.rcgroups.com/flying-wings-211/

That forum has a great CG calculator as a sticky. I have used that and it worked perfectly for me.

And here is a link to a page in German that may be helpful:

http://www.maltemedia.de/swp/

Jack

Great infos, thanks Jack!

I tried RC with flying wings once about 15 years ago when a friend had one. But I found it very hard to fly and not very stable as far as maintaining headings and altitude. So when I came back to RC here about 10 years ago I had no interest in them.

But when Tony65x55's young son took the KFm2 wing up and had no trouble with it at all I figured an old geezer like me should give it another try. And I was simply amazed at the stabilty and ease of flying with this one here (often called the KFm2 Zagnutz). And I built several others in the next few years.

For someone that is building in foam they are a wonderful thing because, with the KF stability, you can build a flat wing from foam, easily embed spars for strength and durability, and still have an easy to fly plane.

There are several videos on my youtube page that were shot from flying wings. Not very good cameras but you can see how easy they were to fly from a rough field flying location and hand launched.

Jack

Same here! When I started with RC planes I havent much interest in flying wings! I liked the traditional planes more. Then I got a Teksumo! One In Hobbyking stock configuration, and one with AUW 398g. Both were great!
Continued with a Z-84, also a great, very stable plane.

In the moment I try to get my first FPV plane in the air with a Matek F405-Wing-INAV. A Chaser C1, which is a scaled up Z-84.

Started to build a FT Simple Storch build as light as possible.
Have to maiden my Tundra.

After that I want to build a 1000mm to 1200mm slow KFm wing. As light as possible! Do you suggest a KFm 2 or a KFm 3 for a slow flying wing?

Have to learn about wing geometry first!

I'd build the KFm3 (2 steps) or even a KFm9 (3 steps) as more steps in the "all steps on top variants" seems to both improve the lift and stability and spread it more evenly across the wing. And, at the same time, the increase in steps means more layers of foam and more places to embed spars and stiffeners.

I'll bet once you get your first scratchbuilt foamie flying wing in the air you'll never buy another one...

I have not used the KFm9 on a flying wing but it worked super for a 96" (2.44m) wing for a glider. You can look at my Big Blu glider build thread for that one.

I'm getting more sedentary and flying less and less as I get older (I'm 76 now) and flying less, I'd love to pursue FPV but don't know if I'll ever get around to it...

Don't worry about the geometry too much, take anything you have flown so far and scale it up or down and it will work. And if it has steps for a KF airfoil it will be easier and cheaper to build and bring you all the joys of easier and cheaper to build.

There is another German man who posts frequently here as Thomas.B over on the Kline-Fogelman building thread that is in the Cologne (Koln) area who is a very prolific builder and who can probably help you with materials and building techniques.

In 1958-1959 I went to high school in Vogelweh (Kaiserslautern area) in Germany when my Dad was an Air Force man stationed in France. And my family has roots to the Bad Nauheim (sp?) area. So, while I have not been to Germany in a long time (last time was in the mid 70's), I have many fond memories of it and ties to it...

Jack

Originally Posted by jackerbes

In 1958-1959 I went to high school in Vogelweh (Kaiserslautern area) in Germany when my Dad was an Air Force man stationed in France. And my family has roots to the Bad Nauheim (sp?) area. So, while I have not been to Germany in a long time (last time was in the mid 70's), I have many fond memories of it and ties to it...

Jack

I think the late 50's and mid 70' has been good times in Germany! Great that you have fond memories about it!

What does "(sp?)" mean?

And thank you again for all the great informations!!!

Uwe

That (sp?) means I am unsure of the spelling...

And I learned many things over there, like what real beer is supposed to taste like compliments of the BBK brewery, and the joys of kissing too... :>)

You are in Munich, no? I have been there too. For Fasching and we went to the Hofbrau House. I was just 17 then and my parents were starting to let me be a young man. I can still hear that song in my mind and see those ladies with four mugs in each hand...

My last year there we had a school in Verdun, France and I lived at home in Sampigny, (Meuse) near St. Mihiel and some of the most historic battlefields of WW I. I would know so little about the history of WW I but for those times.

Jack

The spelling is right!

Fasching is fun in Germany. As a hint the best town in Germany for Fasching is Cologne (Köln).

Oktoberfest is also fun, but mostly for the ones which are drinking alcohol. I dont drink alcohol since 20 years. Maybe once a year, e.g. at New Year.

But both, Fasching and Oktoberfest is fun for the younger ones.

And yes, I am in Munich. Its a lovely town!

I am still waiting for fluorescent transparent covering foil which is on backorder. Hope I will get it soon.