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Old Nov 11, 2010, 05:49 PM
electron fly'r
United States, AZ, Green Valley
Joined Jul 2010
59 Posts
I have followed the KF threads here for about5 years now they seem very interesting. I now have the times into more exploring the KF wing designs. 3 yrs ago I built a "Tony" Pawnee with the following specs. My friend an expert pilot has agreed to be the "test pilot" I could not get the Pawnee to fly well at all. I build out of 1/4" BluFoam coat w/coating both sides.
Specs: Wing is KF3. 48' span, 9" chord incl 1" ailerons full span from fuse.
1st step =3 3/4" from LE,3/4" thick, 2nd step =6-1/8" fm LE 1/2" thick. 1-1/2" from hinge line. wing has flat wing tip caps.
fuse lgt.=32", Power AXI 2212/26 AUW=28oz. CG = 3.5" fm LE
Now to the point of this post. The test pilot & I have made some adjustments gpt it to fly well enough that I can take off and land OK, but this thing is a full handful for me and he says not fun to fly. Upon landing power must be carried till touch down other wise just drops. The only thing we have not done is to increase incidence angle, which I think is zero at present.
I would like for one or more of you to offer suggestions how to make this thing to fly in a less tense manner. It has survived many crashes to this point, I would like for it to fly real well, or it is going to hit the trash.

Part 2 I do want to built a "stick" type fuse to further test the KF varient designs, Want to build wings in the 42-44" span range. Could one of you point me to a post or site for dimensions I will use 1/4" dbl coated BluFoam EPP & wood as needed.

Viking thank you for all your help, learned how to form BF with heat gun from you yrs ago.
Keith
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Last edited by keithflyer_az; Nov 11, 2010 at 06:27 PM. Reason: more info; The alierons were not very effective in the flights today, rudder was much more responsive.
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Old Nov 11, 2010, 09:34 PM
Onward through the fog.
Cybernaught's Avatar
Bohol Philippines
Joined Aug 2008
1,566 Posts
SOB AP plane finished...?

The SOB with new motor mount system seems OK and the swimming is much reduced. Thanks for the suggestions on the cam-mount, Guys. I made it much more secure and used some spongy type foam.
SOB Ses8 AP b.wmv (2 min 44 sec)

Screen grab of the landing area and the SOB broken down for transporting below.

Now for the Taube...


Steve.



Edit; 11/13/10 14:07:00
I had a very nice morning today. After a couple of cups of coffee and a pipe, tobacco is a vegetable, I took the Slinger out to the field and flew the Wing for a change. It's a great way to start the weekend.
Morning Fun b.wmv (2 min 35 sec)

I have the new Taube started and I'm making patterns as I cut the parts out. Span will be 43" based on a PDF design that I think Gene Bond drew up. It will have the early "Etrich" type tail and be full house.
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Old Nov 12, 2010, 06:17 AM
Expat
Japan
Joined Apr 2010
3,123 Posts
OK, so let's say I use the 5mm sheets. 70" wing (180cm). The cord is 22cm. 4 sheets stacked would be 2cm, under the 10%. I guess 3 sheets at 15mm is better for a glider, or not? But I worry about strength issues. BTW, the stock wing is about 27mm at its thickest, but I realize it's not a glider wing.
I have some nice fiberglass rods (180cm) and strips that can reinforce/join the center.
I also have nice PV C that can be used to secure the top for rubber bands, similar to the stock arrangement.
How do I stagger these "steps"? Would you be able to give me specific measurements if it's not too much trouble? Don't worry, I won't hold anyone responsible if there are any problems!
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Old Nov 13, 2010, 11:25 AM
High Altitude Flyer
viking60's Avatar
Fairplay, South Park, CO
Joined Sep 2005
1,608 Posts
Quote:
Originally Posted by keithflyer_az View Post
I have followed the KF threads here for about5 years now they seem very interesting. I now have the times into more exploring the KF wing designs. 3 yrs ago I built a "Tony" Pawnee with the following specs. My friend an expert pilot has agreed to be the "test pilot" I could not get the Pawnee to fly well at all. I build out of 1/4" BluFoam coat w/coating both sides.
Specs: Wing is KF3. 48' span, 9" chord incl 1" ailerons full span from fuse.
1st step =3 3/4" from LE,3/4" thick, 2nd step =6-1/8" fm LE 1/2" thick. 1-1/2" from hinge line. wing has flat wing tip caps.
fuse lgt.=32", Power AXI 2212/26 AUW=28oz. CG = 3.5" fm LE
Now to the point of this post. The test pilot & I have made some adjustments gpt it to fly well enough that I can take off and land OK, but this thing is a full handful for me and he says not fun to fly. Upon landing power must be carried till touch down other wise just drops. The only thing we have not done is to increase incidence angle, which I think is zero at present.
I would like for one or more of you to offer suggestions how to make this thing to fly in a less tense manner. It has survived many crashes to this point, I would like for it to fly real well, or it is going to hit the trash.

Part 2 I do want to built a "stick" type fuse to further test the KF varient designs, Want to build wings in the 42-44" span range. Could one of you point me to a post or site for dimensions I will use 1/4" dbl coated BluFoam EPP & wood as needed.

Viking thank you for all your help, learned how to form BF with heat gun from you yrs ago.
Keith
Keith,

Just from your written description it's hard to tell what might not be working right with your wing / aircraft. Photos with good detail of the wing's leading edge shape, the shape of the wing tip plates, along with photos of the entire airframe might let some of us get a better idea. Without photos, we can only offer some speculation & guesses.

A GUESS: If your wing has a 3/4" thick leading edge which is symmetrically rounded, it may have an effective angle of attack which is far too high. You might try a shim under the wing's trailing edge of from 1/8" up to 1/4". A better approach might be re-shaping the forward 25% of the wing to have more of an airfoil shape; this would drop the entry point of the wing's airfoil & it's effective angle of attack.

1" ailerons are somewhat narrow; increasing their width should increase their effectiveness.

Make sure that your wing tip plates extend about 5/8" below the wing's lower surface. If they do not, tack on some extensions and see if & how they affect how the aircraft flies- if they increase the stability a bit.

Did you do any hand- toss glide tests, power off, to check for ideal balance before your powered flights? If the balance is not optimized for how your particular wing build was done, that could be part of the problem. (Being short on horizontal & vertical stabilizer area, or being very close-coupled without adequate stabilization can be an issue.... again, photos might help get us beyond guessing.)

Looking at other builds for what's said to be flying very well & comparing is still a very good idea, too. Those who say that you can throw a couple of KF steps on anything & it'll fly great may be over-simplifying things a bit too much... enthusiasm is good up to a point... but the rest of the airframe has to be designed to do it's job well, too.
VIKING
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Old Nov 15, 2010, 02:08 AM
Expat
Japan
Joined Apr 2010
3,123 Posts
I'm sure most of you guys know this, but I thought I'd mention that Wingnut won a combat event using a KF wing FireFly.
http://www.rcgroups.com/forums/showp...postcount=1992
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Old Nov 15, 2010, 10:47 AM
Expat
Japan
Joined Apr 2010
3,123 Posts
OK, I guess I'll trail and error. I'm guessing 4 ply is the minimum strength. I'll stagger all the steps evenly. So on a 8.5" cord we're looking at 2" between steps. I'll just stick them all on the top. 5mm depron, as I mentioned earlier, 5mm steps of course. 70" wingspan, joined at the middle. I'll stick some kind of new-fangled wing tips on there for dihedral.
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Old Nov 15, 2010, 06:20 PM
Onward through the fog.
Cybernaught's Avatar
Bohol Philippines
Joined Aug 2008
1,566 Posts
New Taube in the works.

Nice Guy,
Good luck with the wing. I'll keep my fingers crossed for you. I'm curious to see how it works out.

The new Taube is a bit more original looking than my first attempt. It's a KFm2 wing (Surprise) with a 43.5" span and average chord is just over 9" Close to 400sq in area with a Phillip's entry and blunt trailing edge. My plan is to try and balance with the BW stuff but I'll go BP21 if I have to.
Should be fun. I love the way the wing shape looks in the air and I want it to be a bit of a floater. Full house with the more conventional tail but the "bird" look.
Build is with latex paint only over the drywall-tape, no glue in the mix. I'm hoping it will be strong enough and I think it will for smaller builds.
The airframe is finished. See pix.

Additional posts for this bird will be on the Rumpler Taube Coop thread, as they develop.
http://www.rcgroups.com/forums/showt...9#post16560282

Steve.
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Old Nov 16, 2010, 10:52 AM
Expat
Japan
Joined Apr 2010
3,123 Posts
Thanks Cybernaught!
I'm wondering if I have this right: Higher steps, and thicker wings mean more lift, but also more drag, which require more power to fly. So while my wing is similar length and design to Vikings, it will be thicker with thicker steps meaning requiring more power and less "glidey".
I think 4 ply will be just strong enough for that length. If I go thinner, Ill need reinforcement bars, of which I don't have the 'official' stuff, meaning heavy and thick.

I think I'll call this new wing the "Viking"!
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Old Nov 16, 2010, 11:31 AM
High Altitude Flyer
viking60's Avatar
Fairplay, South Park, CO
Joined Sep 2005
1,608 Posts
Quote:
Originally Posted by TheNiceGuy View Post
Thanks Cybernaught!
I'm wondering if I have this right: Higher steps, and thicker wings mean more lift, but also more drag, which require more power to fly. So while my wing is similar length and design to Vikings, it will be thicker with thicker steps meaning requiring more power and less "glidey".
I think 4 ply will be just strong enough for that length. If I go thinner, Ill need reinforcement bars, of which I don't have the 'official' stuff, meaning heavy and thick.

I think I'll call this new wing the "Viking"!
You should probably call it 'The Nice Guy Wing" & leave it at that. There are already 'Viking Wings' out there, and I'm sure you wouldn't want to mislead or confuse anyone!

(And please note that 'fatter' wings don't necessarily generate more lift, and higher steps don't necessarily result in more lift, either...)

If you'll look very carefully over the extensive information in the Dancer thread (& others) about the importance of shaping the forward section of the airfoil, the ideal placement of the maximum airfoil thickness, and about the importance of using shallower step depths to minimize drag, then consider the possible importance of having rigid control surfaces with well tapered / thinned trailing edges, and the affects of various wing tip treatments, you'll have a better idea of what I have developed over the last four+ years in the way of KF variant wing designs. A lot of the more recent information is already posted in many places, so there's little need to load up this discussion thread by repeating it again & again.

Everyone is free to build whatever they want to build... and that's the neat thing about scratch-building foamies- you can build an assortment of test aircraft & see for yourself how they handle, then build another, & another. (Just do everyone a favor & put your own name on your experiments. Thanks.)

DANCER THREAD: http://www.rcgroups.com/forums/showthread.php?t=860461

Here's the "VIKING VOYAGER", A more classic KF3 variant winged sport aircraft designed to fly with detachable EPP floats for float flying; there's more interesting wing tip plate info within this web page:

http://www.stenulson.net/rcflight/voyager.htm

Time to get back to my work... good luck on your project.

VIKING
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Old Nov 17, 2010, 12:53 AM
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AJ750's Avatar
United States, MI, Almont
Joined Nov 2009
523 Posts
hey guys. i just learned to fly last november, and still learning. im defiently a better builder than pilot at this point! the first planes i built i wire cut airfoils out of pink insulation foam. just basic variations of the clark y. then i was introduced to the KFm series of wings. i started with the KFm5a Under camber RET trainer. lots of lift but lots of drag. i call it the MM Special. and now ive gotten into the KFm3 wing and added ailerons to my trainer and i also made a low wing version. the biggest thing ive noticed, is that youve got to travel a lot faster to create the same amount of lift as a UC wing. everything i make is pretty much made of readi-board. cause i have very easy access to it. and i like that its white and not blue or pink.

i dont know, just liked the conversation here and thought id show off what i built.
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Old Nov 17, 2010, 10:17 AM
Expat
Japan
Joined Apr 2010
3,123 Posts
Wowa, that's a bit rough man. I just came here looking for a pleasurable diversion of a hobby. Tried to be nice. We've had a couple of deaths in the family recently and I just wanted to have a diversion with RC stuff.
I looked through your links for several hours and found nothing about making glider wings from 5mm depron. Cyberbaught has spent a hell of a lot more time on here than I have and even he didn't know what to do.
Jesus Christ.
If the answer is so blindingly obvious then just say it. Instead of waiting in ambush for someone.

EDIT:

In my profession I regularly answer questions not required of me just because I can. and I know it will help someone.
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Old Nov 17, 2010, 10:28 AM
fix-it-up chappie
tolladay's Avatar
Valley Village, CA
Joined Jan 2002
2,262 Posts
Quote:
Originally Posted by TheNiceGuy View Post
Wowa, that's a bit rough man. I just came here looking for a pleasurable diversion of a hobby. Tried to be nice. We've had a couple of deaths in the family recently and I just wanted to have a diversion with RC stuff.
I looked through your links for several hours and found nothing about making glider wings from 5mm depron. Cyberbaught has spent a hell of a lot more time on here than I have and even he didn't know what to do.
Jesus Christ.
If the answer is so blindingly obvious then just say it. Instead of waiting in ambush for someone.

EDIT:

In my profession I regularly answer questions not required of me just because I can. and I know it will help someone.
Dude! I think you may have misunderstood his intent, and it is possible he may have misunderstood yours. We are people, after all. Mistakes happen.

Have you considered the idea that there may not be the specific set of data out there that you are looking for? KFm wings are on the leading edge of airfoil design, itself a bit of a leading edge (to abuse the metaphor) of our hobby, and as such are sometimes a "go it alone" field.

btw: I lost both my father, and my father-in-law recently, so I completely understand the need for a diversion. One of the sad things about getting older is burying ones parents.
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Old Nov 17, 2010, 10:53 AM
High Altitude Flyer
viking60's Avatar
Fairplay, South Park, CO
Joined Sep 2005
1,608 Posts
Quote:
Originally Posted by tolladay View Post
Dude! I think you may have misunderstood his intent, and it is possible he may have misunderstood yours. We are people, after all. Mistakes happen.

Have you considered the idea that there may not be the specific set of data out there that you are looking for? KFm wings are on the leading edge of airfoil design, itself a bit of a leading edge (to abuse the metaphor) of our hobby, and as such are sometimes a "go it alone" field.
Tolladay has said it nicely. Misunderstandings are always unfortunate.

Some of us occasionally offer what we have actually proven to work, & we leave the discussion open to others who may have additional experience & suggestions relevant to a given topic.

VIKING
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Old Nov 17, 2010, 11:10 PM
Crash Master
Gene Bond's Avatar
Indianapolis, IN
Joined Sep 2001
16,632 Posts
Quote:
Originally Posted by tolladay View Post
One of the sad things about getting older is burying ones parents.
And siblings...

Glad I missed the apparent dispute. This hobby is for fun.

Thanks for helping moderate, Tolladay... I know it's not your first!

AJ: Yes, more lift and drag on an underchamber wing, but also some other negatives, like strength and wind effects. It's all a tradeoff, but some are so sweet we fall in love!
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Old Nov 18, 2010, 07:42 AM
High Altitude Flyer
viking60's Avatar
Fairplay, South Park, CO
Joined Sep 2005
1,608 Posts
Gene,

No dispute, just misunderstandings. Yes, this hobby is for fun!

VIKING
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