Thread Tools
This thread is privately moderated by maguro, who may elect to delete unwanted replies.
May 03, 2013, 12:07 AM
Must not buy more planes!
mclarkson's Avatar
Quote:
Originally Posted by dave1993 View Post
that is a great idea. i have already cut in half 3 different wing types that were used for my test plane. flat plate, 4-40 uc, and that kf one with the adjustable steps. now i need to figure a good way to join the halves. im thinking 3mm cf tubes with sleeves embedded in the wing roots. and some way to keep them from sliding apart in flight.

it would be interesting to see if there is symmetric handling and if not the other halves could be swapped in to see if tip stall or whatever changed sides.
The guy from Experiment Airlines makes all of his wings break down using two CF arrow shafts.

ANSLEY PEACE DRONE - Setup & Breakdown (8 min 11 sec)
Sign up now
to remove ads between posts
May 03, 2013, 07:02 AM
RC beginner
Quote:
Originally Posted by Dickeroo View Post
Here are Vortex Generators doing their thing...
im not sure if ive posted this photo here before of the vg setup on my test plane. just in case here it is again. results were virtually identical to the kf wing in terms of drag, lift, and stall characteristics. its lighter but does not contribute to wing stiffness at all. and the kf is MUCH easier to build.



it occurs to me this should be included in my version of whiskers half-n-half test. most of the fins have fallen off because they were just attached with double side tape. but shouldnt be too hard to make a new set.
May 03, 2013, 07:31 AM
Jack
jackerbes's Avatar
Quote:
Originally Posted by dave1993 View Post
that is a great idea. i have already cut in half 3 different wing types that were used for my test plane. flat plate, 4-40 uc, and that kf one with the adjustable steps. now i need to figure a good way to join the halves. im thinking 3mm cf tubes with sleeves embedded in the wing roots. and some way to keep them from sliding apart in flight.

it would be interesting to see if there is symmetric handling and if not the other halves could be swapped in to see if tip stall or whatever changed sides.
On the Big Blu 96 glider I used two fibreglass tubes (.260 O.D. x .187 I.D.) as spars and joiners, and the joining was done with .187 fiberglass rods. The rods are have about 2.5" of engagement in the tubes on each side of the joints.

They stayed together nicely just on friction. I was going to add a strip of clear package sealing tape in the field if it seemed necessary or wise but never actually did it.

The details on and source for the tubes and rods is here:

https://www.rcgroups.com/forums/show...6&postcount=14

I actually liked the more flexible nature of the fiberglass tubes over the likely to be more rigid CF tubes (and they were cheaper too). When BB 96 flew it acquired a little more dihedral at the tips from wing flex. It had very good spiral stability and could turn pretty tightly without much bank angle even though I build it with quite a bit less dihedral than Sailplane Calc recommended.

After building a couple of flat KF wings and the polyhedral tip wings with flat center sections and smallish amounts of rise at the tips, I'm pretty much convinced that another trait of the KF wing is that it seems to attain a little more stability with less dihedral than some other wings do.

If you want to fly using the rudder and coordinated controls, pretty much as they would be used in a full sized light aircraft, having a flat KF wing and a four channel setup really encourages the use of all the controls as you mimic those turn with gentle bank angles and play with things like crabbing to correct a lineup or increase a sink rate.

Jack
May 03, 2013, 01:49 PM
just Some Useless Geek
Jack, I also have found that the KF (in particular, the KFm2) increases stability in low dihedral applications. My theory on this is that the step is raising the centroid of lift generation with the disturbance of air created over the wing. I haven't created a test mechanism to gather data on this, but so far my empirical results show that adding a KFm2 step to a low dihedral wing does, in fact, increase the apparent stability by quite a bit. Not quite the effect of adding a gyro, but along that order.
May 03, 2013, 05:08 PM
Jack
jackerbes's Avatar
Thanks for saying that, geek.

It seems like I get slapped around for having an opinion here sometimes...

Now if someone takes my statement "..the KF wing seems to attain a little more stability..." and rephrases it to say that "..the KF wing is the most stable wing in the world..." I take no responsibility for that.

I have no reservations at all on turning a newbie loose for their first flights with a no-dihedral KFm2 or KFm3 wing on a RET only plane. Especially so if they are going to have any help from someone that can already fly.

Jack
May 03, 2013, 09:52 PM
treefinder
springer's Avatar
Interesting observations. Our combat foamies are F&F's and are flat KFM2 wings, most with a bit of anhedral it seems, and they seem to be such great gliders. Stable in glide, and in all power levels, makes it fun to zoom around with streamers on. I kinda wondered why straight leading edge no dihedral wings would fly so well. Perhaps it's the step.
May 04, 2013, 05:45 AM
Jack
jackerbes's Avatar
With anhedral? That's kind of interesting. Is that the OSW or another design? I'm not familiar with combat and the F&F thing...

Can you post a link to that?

Jack
May 04, 2013, 07:28 AM
treefinder
springer's Avatar
There is an F&F thread here on scratchbuilts somewhere. Doesnt comevto first page much anymore. The plane is purpose built for streamer combat; has straight LE to snag streamer, simple build, etc. For some reason most of them, even though built with a dead flat wing, eventually get a slight anhedral arc in front view. Not much, but definitely not dihedral. If you check out the SEMFF thread (always on the first couple pages) you can see pix of the planes and a vid of a sortie posted yesterday.
May 04, 2013, 04:05 PM
Jack
jackerbes's Avatar
OK, I got it:

Muncie group F&F Streamer combat design - https://www.rcgroups.com/forums/show....php?t=1061750

And now I know that F&F = Fast and Furious too.

Being a slow and calm guy, it was the first I had heard of it.

I can see where it might cross my mind to make it as a KFm variant. In view of the venue, KFm4 would probably be a good start.

Jack
Last edited by jackerbes; May 04, 2013 at 04:15 PM.
May 04, 2013, 07:48 PM
treefinder
springer's Avatar
The typical version for our combats is a KFM2 wing frequently with a constant chord step starting at 50% at the tip. Simple fast build, and durable in the foam blender! I also figured that a KFM4 would be a good candidate and built a couple last fall. I was surprized to find that they didn't fly as well as the KFM2 original versions. The only thing I can figure is that the additional thickness added enough additional drag to slow them down a bit, and the plane is short coupled enough that either version is equally acrobatic.
May 05, 2013, 03:03 AM
just Some Useless Geek
Right. That's the trouble with the KFm4 -- if you don't use real thin material it piles up kinda quick and you end up with a barn door in frontal area. Really, really hoping for that 3mm or thinner MPF before indoor season this October...
May 05, 2013, 06:46 AM
internet gadfly
nmasters's Avatar
Quote:
Originally Posted by A Useless Geek View Post
Really, really hoping for that 3mm or thinner MPF before indoor season this October...
I know that mentioning hot wire cutting is kind of anathema in this thread but I just can't resist. I don't do walk along gliders but I get a kick out of watching them on youtube and i learned how to make custom thickness foam sheets in the proses so it wasn't a complete waste of time. It's so simple yet I probably wouldn't have thought of it myself. Here are two videos: The first show the procedure and a super simple cutter. The second one shows the same procedure at 7:30. I have made 2 and 3mm sheet this way and it comes out reasonably uniform. I clamp a regular cutting bow to the table with spacers to hold the wire the desired height above the table.
How to Make a Thin Foam Walkalong Glider (4 min 21 sec)

Walkalong Foam Glider Progress Report (10 min 0 sec)
May 05, 2013, 07:13 AM
Jack
jackerbes's Avatar
Quote:
Originally Posted by A Useless Geek View Post
Right. That's the trouble with the KFm4 -- if you don't use real thin material it piles up kinda quick and you end up with a barn door in frontal area. Really, really hoping for that 3mm or thinner MPF before indoor season this October...
For the F&F a good KFm4 plan might be a sheet of FFF for the center panel and the thinner Readiboard for the KFm4 layers and steps.

The Readiboard is really a nice material, especially in it's newer, easily peeled form.

Dollar Tree Readiboard (bought SEP 2011)
"FOAMBOARD - WHITE"
SKU 82665 30525
ADAMS
R. L. Adams Plastics Inc. Wyoming, MI 49519
www.readiboard.com
Made in the U.S.A.

The URL on the label is not good, this link is good for the product: http://www.adamsplasticsinc.com/inde...d/poster-board

The thickness varies as follows:

Paper on - 0.188"/4.78mm to 0.181"/4.60mm
Paper off - 0.184"/4.67mm to 0.177"/4.51mm

sheet size = 20" x 30" x 0.187" thick (paper on)

thickness - 4.75-4.90mm paper on = 4.8mm nominal
peeled - 4.41-4.66mm peeled = 4.6mm nominal

paper thickness = 0.012mm X 2 (easily peeled dry, leaves clean bare foam)

120-122 grams per sheet as bought, 59-60 grams peeled (the paper doubles the weight!)

600 sq. in. = 4.17 sq. ft
weight = 29 grams / sq. ft. paper on
weight = 14.4 grams / sq. ft. paper off

Jack
May 06, 2013, 12:09 PM
RC beginner
Quote:
Originally Posted by jackerbes View Post
With anhedral? That's kind of interesting. Is that the OSW or another design?
speaking of anhedral youll notice some in my test plane photos. that is not droop. several people commented on it here but because of low Vcg it flies ok. turns a little flat but i never noticed a difference between kf and non-kf in that regard.
May 06, 2013, 04:17 PM
Must not buy more planes!
mclarkson's Avatar
I like 6mm/.25" Dow FFF (Dow Protection Board III Underlayment extruded polystyrene foam board).

It weighs 0.14 grams/in^2 - exactly halfway in between $tree foam with paper (0.19 grams/in^2) and $tree foam without paper (0.09 grams/in^2) - but is much stiffer than un-papered $tree foam.


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) 10262 Yesterday 09:24 PM
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