** Kline-Fogleman (KFm) Airfoils - Building/Flying Discussion ** - Page 642 - RC Groups
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Feb 07, 2018, 04:32 PM
It seemed like a good idea!!!!
Hookit's Avatar
Thanks for that Thomas.

I could not quite make it out, I should have looked on a normal desktop but its not unusual for you to do something innovative in a build.
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Feb 07, 2018, 06:09 PM
I Look, Listen, and Learn
Timbo383's Avatar
Thomas, upon looking at the photo I didn't realize.....and I mean this in a good way....how simple the build looks. I only watched the flight videos on my cell phone so the details were not too clear. I was expecting a more complicated....above my skill levels...build. I know it took some time planning, building and adjustments in which I compliment you on a fine job, the plane looks and flys beautifully.
Feb 08, 2018, 05:33 AM
Registered User
davereap's Avatar
Ive been modifying a 26" EZfly that was a bit fast and heavy.. A FAIL>>>
having been made from 8mm EPP it just didnt fly as slowly as I wanted.

I decided to try out a bigger under cambered wing with a partial KF top step, the centre section got a step and the tips are single layer only..

It got a 2211-1700 kv motor and a 7x4 prop.. an increase in power..
its all done and will get a fly indoors tonight..

all up weight at forward COG is 9 oz... an extra weight was needed... 3.5oz sqft
all up weight at rear COG is 8oz ..weight removed.. 3.1ozsqft

flight report..... no flight.. I got the thrust line wrong and It had much too much down thrust, this kept the nose firmly pushed down, and all it would do was race around on the floor...lol.. even moving the COG a long way back and holding full up only got me a short hop...
It will fly again next week.. with the thrust lines altered.

edit... with new thrust lines it is still poor..so its being binned...
.
big wing EZfly incorrect thrust lines (0 min 30 sec)

.
I went on to fly the fidget.. this small KFm2 model is well aerobatic and is a good indoor flyer, it has a wide speed range and is more competent than I am.. Its one of my favourites.. recommended
Last edited by davereap; Feb 25, 2018 at 12:47 AM.
Feb 10, 2018, 08:07 AM
Registered User
davereap's Avatar
here is the fidgit flight.

fidgit 8feb another easy flight (5 min 57 sec)
Feb 13, 2018, 08:23 AM
Registered User
davereap's Avatar
My flying buddy found this XPS material in the UK at a local B&Q , He gave me a few sheets....
it looks very good..Its 5mm thick and is nice and flat , its light but dense enough
the sheets are 24.5" wide x 31.5".. certainly its well usable..

https://www.diy.com/departments/dial...1570772_BQ.prd

I havnt made a price calculation vs. the hobbyking sheets, but B&Q's are easily found so there is no postage..
Last edited by davereap; Feb 13, 2018 at 08:32 AM.
Feb 13, 2018, 09:26 AM
Jack
jackerbes's Avatar
Looks like good stuff. That looks similar in sizes and qualities to the FFF or Dow Protection Board III we use a lot over here in the colonies.

That is described as an "..extruded polystyrene foam insulation with plastic film on one side..." and it has served us very well. It came in bundles of 25 continuous fan-folded 24" x 48" sheets.

The plastic skin helped with stiffening on one side and using it in layers and adding spars of various types and in various places let us use it up to the full 48" width in one piece.

I still like the use of colored package sealing tape to give builds color and also strengthen the bare foam side. I put a spray of contact adhesive on and then the tape and it make a major contribution to strength.

Jack
Feb 14, 2018, 05:59 AM
Reap the wild wind
headlessagain's Avatar
Quote:
Originally Posted by davereap
My flying buddy found this XPS material in the UK at a local B&Q , He gave me a few sheets....
it looks very good..Its 5mm thick and is nice and flat , its light but dense enough
the sheets are 24.5" wide x 31.5".. certainly its well usable..

https://www.diy.com/departments/dial...1570772_BQ.prd

I havnt made a price calculation vs. the hobbyking sheets, but B&Q's are easily found so there is no postage..
They used to sell a similar material a few years ago. It lacked the markings and locking tongues. From memory it was a little softer and not as smooth skined as Depron. I've also used the XPS foam sold by underfloor heating companies which is similar to the old B&Q foam
Feb 15, 2018, 01:51 PM
scratchbuilder
Thomas B.'s Avatar

KFm 2 Ekranoplan on the Rhine


Now it is ready and coloured. Great fun.
Ekranoplan auf der Wolga (1 min 21 sec)
Feb 15, 2018, 02:29 PM
"long stretch of water..."
coongoola's Avatar
Very nice Thomas. Thanks for posting.

Pat
Feb 16, 2018, 08:07 AM
Registered User
davereap's Avatar
here is one that took my fancy...a mini blitz..
It should be good with a 2204-2300 on 2s , 6x4 prop ...
redrawn for foam using a KFm2 build.. I can try out the B&Q 5mm foam
I enlarged the elevons a touch, but tried to keep the remainder fairly accurate..
The actual balsa plans were a give away in Decembers 2016 RCM&E..
They have been resurrecting older designs.. a lot of which are suited for foam and a KF wing

edit for COG position... nose heavy is 1" in front of the step at the root...
better is 1/2"-3/4 in front of the step at the root ..this is the forward position marked on the plan

Over sensitive , perhaps just flyable is the rear marked location...not recommended..
Last edited by davereap; Feb 22, 2018 at 05:04 AM.
Feb 16, 2018, 09:33 AM
Reap the wild wind
headlessagain's Avatar
Both my KFm delta pullers flew well. The first was EPP and the second 6mm Depron The latter also had a rudder on the single fin which enabled it to spin!
EPP RC Flying Wing (3 min 12 sec)

Andy
Feb 16, 2018, 11:44 AM
flyin' fool
goldguy's Avatar
Quote:
Originally Posted by davereap
here is one that took my fancy...a mini blitz. The actual plans were a give away in decembers RCM&E
I've got the plan for both the Mini and Micro Blitz, a free plan from RCM&E NOVEMBER 1995!! Built a few of both, TD .049 and 020 power. Wonderful designs, great fliers and lots of fun in the wind. I've built and seen a few electron powered versions posted here on RCG.

Thanks Dave for bringing it back once again and your perfect plan.
Feb 17, 2018, 01:55 AM
Registered User
davereap's Avatar
a single fin is an easy mod... like here.. sketchup file included ..make as big as you like..

the fin size here is only my guesstimate .. it may be worth starting a touch larger and cut it back as needed.
Last edited by davereap; Feb 17, 2018 at 02:04 AM.
Feb 17, 2018, 02:54 AM
Reap the wild wind
headlessagain's Avatar
I'd certainly go with a rudder as this will give you some more aerobatic options e.g. inverted spins
Just seen a video posted by Nick Robus ( Soar Ahead Sailplanes) on my mate Matt's Facebook group (Rag The Nuts Off) where he was flying his new indoor wing at your clubs indoor venue. I guess it won't be long till you build as KF version. Purely for comparison reasons of course
Andy
Feb 17, 2018, 11:52 AM
Registered User
davereap's Avatar
The tiny wing is not for me..I have problems with the ultra mcro stuff, its just too small.. it does however go reasonably well..

the Blitz/E-BlitzerKFm2 is being built, using the B&Q foam..
I scaled it up a touch, to a 22" span and added that central rudder..

The new foam itself is not too bad, its more easily snapped than depron, it feel lighter.. keep the iron temp down to 125c its also more easily melted than depron.
Its more similar to the hobby king material..

I have made extensive use of laminating film for reinforcing.. covering the KF layer area above and below the wing, and the tail fin/rudder , trailing edge and elevons.
The end result is nice and stiff , with no spars ..
weight here at 4.12oz

I made the fin and rudder slightly larger than my original guess..by about 1/2" in height, plus a bigger rudder...+1" wider
The way its balancing at the moment is very nose heavy..

edit..... All the servos had to go to the rear and the 450 2s lipo was put just behind the rearward COG..
This got the COG back to the rear 25% position, which is spot on at the step line at the root..This is too far back and not recommended
The battery has plenty of room to move forward to get the COG at the 20% spot. COG OK here
go to 1" forward of the step at the root for first flights COG..

On a 2s there seems to be more than enough thrust..in fact when flown it gave full vertical performance and good speed
Just over half throttle was used on hand launches.
The fuz has room for a 3s if needed... this would be way more than is needed..

motor in place is a 2206-2280kv.. 3x hxt500 servos will be used..
AUW with a 450 2s is 7oz and with a 750 2s is 7.38oz.. wing loadings of 4.165ozsqft and 4.4 ozsqft respectivly
Last edited by davereap; Feb 22, 2018 at 05:09 AM.


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