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Old Oct 04, 2009, 09:45 AM
just Some Useless Geek
Chicagoland
Joined Oct 2008
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Quote:
Originally Posted by Dickeroo
My friend, Tony Chang (Ghostfit), just sent me a video of a ten year old boy flying a SlowStick with a KFm2 airfoil.
Hey, Dick? That Corostick kinda looks tail heavy, don'tcha think? The way it was high AoA all the time, the handling at low speeds, etc. I'm kind of surprised it wasn't set up fairly nose heavy instead, since that's the way most training is done. Hmm.

And the tunes? Mick-Jiver! Heh, heh.
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Old Oct 04, 2009, 09:48 AM
Geaux Saints
Hopalong X's Avatar
Grafton, Il
Joined Nov 2007
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j2m2t2

You won't tell any difference in performance on R/C with gear on top or bottom.

It is much safer for the equipment on top.

When you have no landing gear put the servos on top. Less damage.

If you were out to set speed records all your gear would be contained and aerodynamic for maximum speed.

Mike
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Old Oct 04, 2009, 10:13 AM
Jack
USA, ME, Ellsworth
Joined May 2008
16,681 Posts
I'm gathering up the material to build in Coroplast. Going to build one of each of these two under the tutelage of a saltly old coroplast builder and flier (Jerry_In_Maine).

63" advanced trainer - http://www.spadtothebone.com/SPAD/Spadet/

52" Sport flier - http://www.spadtothebone.com/SPAD/SpadStick/

These are going to be electric of course. The material costs are quite a bit higher and some of it is harder to get. I think we'll have about $15-25 each in these just in the Coroplast because we were not able to come up with that for free or on the cheap up here in the wilds of Maine.

But it adds a whole new dimension to tough and durable I'm told. Like you can use them for driving fence posts when you're not flying. Or something like that anyway...

Time will tell!

And guess what? Neither of them will have a KF wing! But I'm already planning to fly them as designed for initial data collection and to get the feel of them. And them I can easily tape a piece of FFF to the wing tops to turn them in to a "Clark-Y converted to KFm2" comparison.

May have those ready to go within a month or so. Will needs skies on it of course, winter flying from frozen lakes, what a lovely venue.

Jack
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Old Oct 04, 2009, 10:27 AM
PunchDrunk ex-Pug try'n fly'n
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United States, MN, Minneapolis
Joined Jan 2009
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Chord measure

I have wondered about this as well. my question is what about the motor/prop cutout on a pusher? I use the measurements without Elivones or motor cutout.

I put my servos on top and shallow for easy access. My biggest issues are getting that CG far enough forward.
jp
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Old Oct 04, 2009, 10:30 AM
Geaux Saints
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Grafton, Il
Joined Nov 2007
1,913 Posts
Jack

Looks like you could build a seperate KFm wing later to interchange with the original.

Looks like you might have found a spot for the DAT-750 motor.

Mike
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Old Oct 04, 2009, 11:18 AM
Jack
USA, ME, Ellsworth
Joined May 2008
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Those guys are both up in the 4-6 pounds range and calling for .40 to .46 fuelies so something up aroung 500 to 750 watts would compare better to the power needs there.

I think the DAT-750, at 200 Watts and 2.2 lbs of thrust could get the lighter of the two in the air OK but will be a short on power for winter flying in Maine or the occasional cheap too much power thrill.

I'm looking at the DAT-750 as being a candidate for ApachePilot's Divinity Millennium (still a work in progress, no plans yet). That will be 72" span but much lighter, maybe around 1.5 pounds or so the way I build. With the 750 Kv I think that DAT-750 will throttle back to 80-100 watts or so with a big slow fly prop and meet all my needs for the Millennium.

This OK-C3542-A is the leading candidate for the SpadStik, 127 grams/5 oz., Kv 1450, 4.4 lbs of thrust, and 400 watts or so:

http://www.nitroplanes.com/c3exoubrmo11.html

That is a seldom found out of production motor, there is little or no data around for it, and it came to me for about $15 (too cheap to not buy it) via eBay. It cries out to be used though as it bench tested very nicely. Pretty frightening with a APC 10 X 6 on it.

The Spadet is bigger and a little heavier. I think I might invest in one of those cheap bigger (32-35mm or so) Turnigy motors that are getting good reports over on the fuel to electric conversion forum.

How about you? Is your's gainfully employed yet? I read a recent report that the motor shafts on those are turning out to be a little soft and bend easily. Some have been replacing them with 5mm shafts that are of better quality. That will be easy enough to do.

Jack
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Old Oct 04, 2009, 12:28 PM
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Ashford. Kent. England
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Initialy the chord measurements were to include the elevons, but by now you will realise that most of us have positioned the steps, measuring with and without the elevons, and whatever we do the steps work.. Ive also put mine at anywhere between 40-50% and its ok... also had steps that are 50 at the root and 40 at the tips..
The difference in positioning, luckily, is not critical and I would think that most of us could not feel any difference in the way the plane performs, providing the step goes somewhere near where it is suposed to.
Early tests to find the best location for the top steps KFm2 were made with a small glider model, no ailerons..these tests found the best glide was at 50%, so thats what we go with..however the little glider went ok at 40%.
And we fly power so will not notice small variations
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Old Oct 04, 2009, 01:02 PM
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j2m2t2's Avatar
AZ
Joined Feb 2007
526 Posts
Quote:
Originally Posted by davereap
Initialy the chord measurements were to include the elevons, but by now you will realise that most of us have positioned the steps, measuring with and without the elevons, and whatever we do the steps work.. Ive also put mine at anywhere between 40-50% and its ok... also had steps that are 50 at the root and 40 at the tips..
The difference in positioning, luckily, is not critical and I would think that most of us could not feel any difference in the way the plane performs, providing the step goes somewhere near where it is suposed to.
Early tests to find the best location for the top steps KFm2 were made with a small glider model, no ailerons..these tests found the best glide was at 50%, so thats what we go with..however the little glider went ok at 40%.
And we fly power so will not notice small variations
Again thanks. I wasn't sure if a small change in measurements like 40% or 42% would cause unwanted characteristics.

Hopalong X Im interested in learning about the KF step, that is why all the questions. Also Im not going for perfection but it would be nice to know exacts even for RC.
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Old Oct 04, 2009, 02:01 PM
Geaux Saints
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Grafton, Il
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j2m2t2

Sent you a PM.

Mike
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Old Oct 04, 2009, 04:44 PM
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Ashford. Kent. England
Joined Feb 2005
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For the majority of our builds here the drag from having the gear out and dirty wont be a problem.
If you are trying to get absolutly the best performance out of any design then enclosing the bits in a streamlined body or wing makes good sense.
As does getting the steps in the best positions. Or using the best airfoil section.

personal thought here... I like a cheap quick build so all of my designs/builds have the gear on top and I can swap componants with no trouble in seconds. I am not after the fastest of planes so any drag will help keep the plane at a reasonable speed. And the speeds I have been getting are plenty fast enough for where I fly. Most of the time I fly on half power and thats fast enough for me

j2m2t2
Have you had a read through the other KF thread..here.. http://www.rcgroups.com/forums/showthread.php?t=558321
The info on variations in KF posiions and types are all laid out showing what has given the best results..Its a massive lot to go through but will give the best guide as to what does and what doesnt work..luckily for most of us the KF steps have almost always worked even when weve used the wrong locations and/or depths.. It is a forgiving airfoil, and since I started using it I now put a step or two on any wing, even deltas and circular shapes..I believe it benifits the wing and that helps me fly it better...Is that just psychological...or psycho
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Old Oct 04, 2009, 06:09 PM
Onward through the fog.
Cybernaught's Avatar
Bohol Philippines
Joined Aug 2008
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Quote:
Originally Posted by davereap
For the majority of our builds here the drag from having the gear out and dirty wont be a problem.
If you are trying to get absolutly the best performance out of any design then enclosing the bits in a streamlined body or wing makes good sense.
As does getting the steps in the best positions. Or using the best airfoil section.

personal thought here... I like a cheap quick build so all of my designs/builds have the gear on top and I can swap componants with no trouble in seconds. I am not after the fastest of planes so any drag will help keep the plane at a reasonable speed. And the speeds I have been getting are plenty fast enough for where I fly. Most of the time I fly on half power and thats fast enough for me

j2m2t2
Have you had a read through the other KF thread..here.. http://www.rcgroups.com/forums/showthread.php?t=558321
The info on variations in KF posiions and types are all laid out showing what has given the best results..Its a massive lot to go through but will give the best guide as to what does and what doesnt work..luckily for most of us the KF steps have almost always worked even when weve used the wrong locations and/or depths.. It is a forgiving airfoil, and since I started using it I now put a step or two on any wing, even deltas and circular shapes..I believe it benifits the wing and that helps me fly it better...Is that just psychological...or psycho
Hey Folks,

Let me wade in on this too!
It's real easy to use a soldering iron to make slots in the foam for the RC, ESC. I bury my gear when I have the placement where I figure it's right for the wire lengths and for a good CG. I make slits with a razor knife and push the servo wires into the foam. Motor wires are in a soldering-iron-slot. Tape goes over the top. I oversize the ESC a bit and over heating without good ventilation has not been a problem so far. I recess my servos and put them in straight up so I can get to the servo arm screw with a jewelers screwdriver and while mounting them on their sides is more aesthetically pleasing and a bit cleaner, it's not as convenient. Like Dave, I put everything on top. Slot and Velcro for the battery makes changing it out easy!
See before and after pictures.

I use a 50% KFm2 or 4 now on everything. In the % designation I include ailerons or elevons because that adds thickness to more of the wing for strength. Like Dave, I find the 10% or so difference in slot placement does not produce a noticeable difference in performance.

Dave you said using a stepped foil gives you a "Psychological" advantage. I believe it's real and I can't imagine the need for a conventional wing-form when the KFs provide so many advantages that have been demonstrated to my satisfaction in my own experience and in the comments others have made here. Other opinions may differ but they are all just plain wrong!! Aerodynamic theory to the contrary seems to abound but what works, works!

Happy Landings and Mabuhay to you all.
Steve.
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Old Oct 04, 2009, 08:44 PM
PunchDrunk ex-Pug try'n fly'n
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United States, MN, Minneapolis
Joined Jan 2009
1,014 Posts
Quote:
Originally Posted by davereap
.....luckily for most of us the KF steps have almost always worked even when we've used the wrong locations and/or depths....
Well being the "tinkerer" that I am I have found a couple of step options that have not worked. As Apache pilot put it the step could be thought of as a force that pulls up when it is on top and down when on the bottom. Thus, as you get farther away from the CG it will effect the planes attitude to a greater degree.
I had a few KFm's with a bottom step to far forward of CG, some with top steps to far aft of the CG. And at least one with both of these errors. This caused a nose down attitude when not under power.
My thinking was along conventional terms and wrong for the KF.
After reading a post from Apache Pilot the light bulb went on!
Now I am building with more attention to the vortex forces acting in conjunction with the CG.
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Old Oct 04, 2009, 09:03 PM
PunchDrunk ex-Pug try'n fly'n
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United States, MN, Minneapolis
Joined Jan 2009
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Report on KFm with Four steps over Zero

Well here is yet another successful mod.
I have not computed the %"s but I have four steps basically as far forward as I could put them with at least 1.5" between. FFF with no spars or spacers.
I used an extended nose for the battery to get the CG @5" on just a 14 degree sweep. Here is an idea of the dimensions;
http://fwcg.3dzone.dk/?wing_span=48&...ow_mac_lines=0
It flew and glided very well
My only complaint was with my first use of cables instead of control rods. I'll be going back to rods. I like the idea of standing them up to expose the control horn set screw. Thanks to Steve for the tip!
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Old Oct 04, 2009, 10:04 PM
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AZ
Joined Feb 2007
526 Posts
Flew the rebuilt FFF glider today. Much better than the EPP version. Glide was unbelievable. Thanks for all the input. Pics can be seen at the thumb wing thread.

My step varies from 40% at center to 50% at wing tips. 1/8 spar.
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Old Oct 05, 2009, 06:08 AM
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Ashford. Kent. England
Joined Feb 2005
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quote Flew the rebuilt FFF glider today. Much better than the EPP version. Glide was unbelievable. Thanks for all the input. Pics can be seen at the thumb wing thread.

a link please for us lazy people ...dave



Perhaps we should also post where not to stick a step...
When I said they mostly work, I meant with reasonable positions..A bit off here and there and the steps are still ok
I wouldnt for instance stick a KFm2 at 20% or 80% when the target location should be 50%.
Best always to be fairly accurate knowing what is required, but a bit moved here or there if needed is acceptable
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