Thread Tools
Jan 19, 2020, 05:02 PM
Registered User
Thread OP
Discussion

Kfm3+


Has anyone experimented with more than 2 steps?

I'm also currently considering a design that'd need the first step closer to the leading edge. Before I go in that direction, has anyone got any experience that should put me off that pursuit and stick strictly to 50% chord?
Sign up now
to remove ads between posts
Jan 19, 2020, 05:19 PM
Registered User
Thread OP
I've found this

https://www.rcgroups.com/forums/show...postcount=1808

And noticed the Kfm9 is effectively what I'm designing for.

Still, how dependent are kfm foils on the step position?
Last edited by zioruk; Jan 20, 2020 at 05:21 PM.
Jan 19, 2020, 07:36 PM
Registered User
Flow separation on a normal airfoil usually occurs at roughly 30%, that's where the KFM step should be placed.
You can add a second step at 55%. Each step should be (ideally) 33% high of the total airfoil thickness.

Steps at the undersite are a different story; ideally 1/3 of the airfoilheight and at 50% from the leading edge.
Jan 19, 2020, 08:25 PM
treefinder
springer's Avatar
On the first page, second post, is a chart of current KFM variants. https://www.rcgroups.com/forums/show...cussion-%2A%2A

They are up to kfm11!

A member username viking (plus a number, I think ) has played with enough steps to approximate a conventional airfoil.
Jan 21, 2020, 07:58 AM
Registered User
davereap's Avatar
Ive tried lots of variants... It just depends on your aims for the wing.. for multi steps The first step I usually set at about 25-30% chord and that is the thickest part of the wing, where the main spar would go.. additional steps are spread evenly over the remainder of the wing..
For the simpler wings follow the guide for positions.. and you wont go too far wrong..

step locations are not critical..the guides to %age locations are where they worked ..
Jan 21, 2020, 09:47 AM
treefinder
springer's Avatar
Finally found it the username is Viking60! Looks like most of his fiscussionbof multiple step wings is in the two KFM sticky threads at top of forum first page. Well worth a read or some key word searches.


Quick Reply
Message:

Thread Tools

Similar Threads
Category Thread Thread Starter Forum Replies Last Post
Discussion KFM3 Wing Looking For A Mate ninjasword71 Foamies (Scratchbuilt) 3 Sep 23, 2017 11:10 PM
Question KFM3 Airfoil swapnilnimbalkar Foamies (Scratchbuilt) 35 Apr 07, 2017 04:16 AM
Discussion Big Stable KFm3 Delta [build info & video] nelsoneci Foamies (Scratchbuilt) 25 May 04, 2016 11:43 AM
Discussion Pics of my AP KFM3 Flying Wing SpinningInPres Aerial Photography 1 May 24, 2008 07:52 PM