HobbyKing.com New Products Flash Sale
Reply
Thread Tools
This thread is privately moderated by jackerbes, who may elect to delete unwanted replies.
Old Dec 08, 2009, 04:17 AM
Registered User
davereap's Avatar
Ashford. Kent. England
Joined Feb 2005
6,908 Posts
tom
I am a KF fanatic but for very slow and indoors an ultra light flat plate is better than a heavier KF build... Its all about the finished weight...lighter is slower.. and indoors you want small and as light as possible..

take a look at this build for epp
http://www.rcgroups.com/forums/showthread.php?t=964237
the fluffy Yak is good for indoors and there is a big KF version for outside here
http://www.rcgroups.com/forums/showp...0&postcount=29
davereap is offline Find More Posts by davereap
Reply With Quote
Sign up now
to remove ads between posts
Old Dec 08, 2009, 07:42 AM
Always looking for lift...
sky_surfer_fra's Avatar
Germany, HE, Offenbach
Joined Oct 2003
379 Posts
That makes sense to me davereap.
Thank you.

Quote:
Originally Posted by davereap View Post
tom
I am a KF fanatic but for very slow and indoors an ultra light flat plate is better than a heavier KF build... Its all about the finished weight...lighter is slower.. and indoors you want small and as light as possible..

take a look at this build for epp
http://www.rcgroups.com/forums/showthread.php?t=964237
the fluffy Yak is good for indoors and there is a big KF version for outside here
http://www.rcgroups.com/forums/showp...0&postcount=29
sky_surfer_fra is offline Find More Posts by sky_surfer_fra
Reply With Quote
Old Dec 08, 2009, 07:53 AM
Always looking for lift...
sky_surfer_fra's Avatar
Germany, HE, Offenbach
Joined Oct 2003
379 Posts
Thanks Jack.

EPP is much more stable than Depron but weights more .
Wikipedia: EPP - Expanded Polypropylene, a form of foam polypropylene
I really like this stuff for all planes that have to operate under difficult (landing) environment conditions.
With this ships I fly e.g. at slopes that I never would do with a wood or carbon ship.
Elapor (e.g. EasyGlider, EasyStar, Cularis from Multiplex) is also an EPP flavour.

Quote:
Originally Posted by jackerbes View Post
Tom wrote:

".. Looks interesting. But how to build these with EPP ..."

I'm a EPP deprived person. But there are a bunch of guys using it. It is Depron or something like that, right?. If you look at some of the threads for indoor slow flyers or slow flyers in general I think you can either find builds in Depron or figure out how to use it. I'm more into outdoor planes. If you look at threads for Blu Baby, Divinity, Zagnutz, and planes like that you should find some info on EPP builds.

Maybe some of the EPP guys will jump in here and suggest some builds for you.

Jack
sky_surfer_fra is offline Find More Posts by sky_surfer_fra
Reply With Quote
Old Dec 08, 2009, 04:41 PM
Onward through the fog.
Cybernaught's Avatar
Bohol Philippines
Joined Aug 2008
1,566 Posts
Quote:
Originally Posted by sky_surfer_fra View Post
Thanks Jack.

EPP is much more stable than Depron but weights more .
Wikipedia: EPP - Expanded Polypropylene, a form of foam polypropylene
I really like this stuff for all planes that have to operate under difficult (landing) environment conditions.
With this ships I fly e.g. at slopes that I never would do with a wood or carbon ship.
Elapor (e.g. EasyGlider, EasyStar, Cularis from Multiplex) is also an EPP flavour.
Hey SSF,
Good luck with the EEP build. The KF stuff works very well. I'm a big fan too. Just remember that nothing is bullet proof. I know!

Just trashed the Pagan ZZ. Too many lawn dart landings in the wind. Saved the wing for a boomer mod. Now it's another coffee then back out to the garage. 6:39 here on Wed. windy again!!!

Dave,
Didya get a break in the weather yet? How's the camera plane coming? Ready to maiden her yet?

Steve.
Cybernaught is offline Find More Posts by Cybernaught
Last edited by Cybernaught; Dec 08, 2009 at 04:49 PM.
Reply With Quote
Old Dec 08, 2009, 04:41 PM
just Some Useless Geek
Chicagoland
Joined Oct 2008
2,541 Posts
Quote:
Originally Posted by davereap View Post
I am a KF fanatic but for very slow and indoors an ultra light flat plate is better than a heavier KF build.
Gotta call you on this one, Dave. I agree that lighter is better, but only for absolute performance critics. The original requirement was for "an easy to build airfoil that I can use on a very slow flying EPP indoor plane." Note that sky surfer isn't asking for a maximum performance plane, just one that flies slowly. The KFm2 is a perfect match for that requirement.

Once again allow me to point out that I have done the experiments with the KFm2 on a few of my own planes. For absolute top performance I went with a single layer of Pink, but for slow indoor flying I still prefer the KFm2 for its simplicity and effective airfoil behavior. My Smarty Pants Dart is the ideal demonstration engine for that purpose. Look around here and you'll see the videos I made comparing one Dart to another and one wing to another.
A Useless Geek is offline Find More Posts by A Useless Geek
Reply With Quote
Old Dec 08, 2009, 04:44 PM
Onward through the fog.
Cybernaught's Avatar
Bohol Philippines
Joined Aug 2008
1,566 Posts
Quote:
Originally Posted by A Useless Geek View Post
Gotta call you on this one, Dave. I agree that lighter is better, but only for absolute performance critics. The original requirement was for "an easy to build airfoil that I can use on a very slow flying EPP indoor plane." Note that sky surfer isn't asking for a maximum performance plane, just one that flies slowly. The KFm2 is a perfect match for that requirement.

Once again allow me to point out that I have done the experiments with the KFm2 on a few of my own planes. For absolute top performance I went with a single layer of Pink, but for slow indoor flying I still prefer the KFm2 for its simplicity and effective airfoil behavior. My Smarty Pants Dart is the ideal demonstration engine for that purpose. Look around here and you'll see the videos I made comparing one Dart to another and one wing to another.
I agree... If you can build light and still supply enough power the KFm2 has an impressive speed range. From dead slow to good and fast.

Steve.
Cybernaught is offline Find More Posts by Cybernaught
Reply With Quote
Old Dec 09, 2009, 05:38 AM
Registered User
davereap's Avatar
Ashford. Kent. England
Joined Feb 2005
6,908 Posts
I am still waiting on a break in the weather... wet and windy here yet again...
The glider/cam plane's fuz is still being built, 80% done, just the front skins of the body to fit and shape.. Ive just got a big card for the cam, so now I can take more than 4 mins of video..so we are looking good..

I will post a build if it turns out ok, or I will bin it, if its a dog...

Geek.. I now always use a KF build ... but I still think a lighter build or a lower wing loading equates to slower, and that extra skin adds weight, unless you can modify the build to compensate..And that depends on the design...so more area.. same weight = a lower loading so it will fly slower..
If all that is wanted is ultra slow then that factor plus the available material will determine the design..A KF step might then improve the flight, but I am not convinced that at very slow speeds it has noticable advantages... But at all normal flight speeds yes it does...thats why I always use the steps
If I wanted a plane that goes slow enough for indors but also flys normal for outside then your dart would be ideal, it is indeed very good and a simple build.., But if I wanted a more dedicated slow flying aerobat for indoors then I would prefer the Fluffy Yak
davereap is offline Find More Posts by davereap
Last edited by davereap; Dec 09, 2009 at 05:48 AM.
Reply With Quote
Old Dec 09, 2009, 06:13 AM
Crash Master
Gene Bond's Avatar
Indianapolis, IN
Joined Sep 2001
16,632 Posts
IMO, slow-indoors means high drag + high lift... this equates to underchamber.

BUT, if you want aerobatic, then you probably want symetrical, which gets you right back to KFM4

For example, look at F3P. They use brakes and other drag-increasers. The closest, super-slow plane I can think of is Bill Lowe's Ghost: http://www.rcgroups.com/forums/showthread.php?t=812288 It's a variation on KFm4, IMO.
Gene Bond is offline Find More Posts by Gene Bond
Reply With Quote
Old Dec 09, 2009, 10:49 AM
just Some Useless Geek
Chicagoland
Joined Oct 2008
2,541 Posts
I flew a demo Ghost at last year's December SRCB E-Niter. That thing is incredible. However, it belongs in the hands of people who know exactly what they're doing. It also needs to be flown in a venue of like skilled pilots. Surfer was asking for an EPP plane, so that is a sure clue that he wants something crashable.

Perhaps surfer anticipates midairs at his indoor venue. I only fly two commercial indoor venues, and the one that has more open space is the one that also collects all the midairs. Choosing to fly EPP in such an environment is a good defensive posture to take under such conditions.

So, that brings us back to the use of a KFm2 wing on an indoor plane. I've used the KFm2 on five plane patterns so far, although I've only done direct A-B comparisons on one of them. A couple other guys have built Yardarms without the step and I've flown those next to KF Yardarms with the same results I got on the SDXS; the stepped wing slows the plane down but allows for a much higher Alpha and much more controllable low speed maneuvering.

One last note on the KFm2: the step adds lateral stiffness to the wing when it is fully surface glued. By laminating the step on to the top of the wing you add a semi-rigid plane within the wing itself, eliminating the need for carbon fiber rods and such stuff. I added a wing brace on the Yardarm and the Chinese Noodle because the span was just too long to go without it. But on my smaller planes there is no bracing in the wing at all. Keeping in mind that surfer wants an easy to build wing that flies slowly, I can't think of a superior alternative.
A Useless Geek is offline Find More Posts by A Useless Geek
Reply With Quote
Old Dec 09, 2009, 11:22 AM
Registered User
davereap's Avatar
Ashford. Kent. England
Joined Feb 2005
6,908 Posts
The glider/cam plane is almost there just some shaping and a few final tweeks

I am expecting a final weight ot 15oz with a 3cell 1250 lipo thats 6.6 oz sq ft
davereap is offline Find More Posts by davereap
Reply With Quote
Old Dec 09, 2009, 02:12 PM
Registered User
Salty79's Avatar
United States, AR, Benton
Joined Jul 2009
166 Posts
I have a couple questions for the experts. I would like to set up a KFM4 for a Leadfeather Yak 55. On a plane like this the ailerons make up almost half of the wing area, should I include the ailerons in my chord length. I'm trying for 50% chord at the root and 40% chord at the tip.
Salty79 is offline Find More Posts by Salty79
Reply With Quote
Old Dec 09, 2009, 02:39 PM
Registered User
davereap's Avatar
Ashford. Kent. England
Joined Feb 2005
6,908 Posts
check what they did on the 42" big version KFm4..that can be your guide
http://www.rcgroups.com/forums/showthread.php?t=1102742
davereap is offline Find More Posts by davereap
Reply With Quote
Old Dec 09, 2009, 06:22 PM
Registered User
Salty79's Avatar
United States, AR, Benton
Joined Jul 2009
166 Posts
davereap,

It's is while building that very plane, that the question came to me. If you took the time to look at the plans Here you would see that the KFM strip is just lined up with the CG....A little calculator time later I get 33% at the root and 41% at the tip. I have never seen that used and have never used that on any of my other foamies. My question was well thought out. Please answer with like.


I will reword my question.
Should the chord of large ailerons, like those found on many 3d planes, be considered in the placement of the KFM4 step? and If so by how much?

Salty
Salty79 is offline Find More Posts by Salty79
Reply With Quote
Old Dec 09, 2009, 08:50 PM
Registered User
Neenah, WI
Joined May 2006
387 Posts
Quote:
Originally Posted by Salty79 View Post
.... should I include the ailerons in my chord length.
Yes.
Complete wing-chord is from the leading-edge of the wing to the trailing-edge of the aileron.
gyrocptr is offline Find More Posts by gyrocptr
Reply With Quote
Old Dec 09, 2009, 08:58 PM
Crash Master
Gene Bond's Avatar
Indianapolis, IN
Joined Sep 2001
16,632 Posts
I always use the full chord (wing + Aileron), unless I feel the bubble might fall past about 1/2 the chord of the airleron... in which case I cheat the step forward.

Clear as mud?

The good thing is that it soesn't have to be exact to get good results. Great results may come from additional experimentation, but so far, so good

On my KFm4 Extra, I went about 25% at the root, and about 40% at the tip, so the step was straight across.
Gene Bond is offline Find More Posts by Gene Bond
Reply With Quote
Reply


Thread Tools

Similar Threads
Category Thread Thread Starter Forum Replies Last Post
Idea 40" Depron Dynamite, Kline fogleman Depron build dougmontgomery Hand Launch 636 Jul 12, 2014 06:29 PM
Cool Here is my KFm-5 DLG GLider (Kline-Fogleman) dougmontgomery Foamies (Scratchbuilt) 151 Apr 21, 2014 09:08 AM
Discussion ** Kline-Fogleman Airfoiled Flying Wing ** Tony65x55 Foamies (Scratchbuilt) 3945 Apr 08, 2014 10:40 AM
Video Kline Fogleman Airfoil on a flying wing Tony65x55 Electric Plane Talk 3 Jan 30, 2009 07:37 PM
Discussion Kline-Fogleman Airfoil on a flying wing Tony65x55 Modeling Science 1 Aug 20, 2006 11:14 AM