A simple build Plank with KFm4 section.. with WOW! factor.. Called it the "Nifty" - Page 5 - RC Groups
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Jul 14, 2009, 08:15 PM
Onward through the fog.
Cybernaught's Avatar
Originally Posted by davereap
things to watch for.. flatter acceleration at 1.30... a nice long parachute descent at 1.45... inverted at 2.36 ...rolls and loops all over
Hey Dave,

I'll download your vid when I can get to Calape and the cybercafe. Winds stronger today. Just checked PAGASA, PI's weather center and there are red spots all over the sat-map. Looks like most of it will pass t the north of us but we still get the high winds from it.

I may take the Thistle up for a high wind test flight. My plan is to spend a bit of time in the garage and try to come up with a high wind stretch-delta. Around 2.5 sq ft area and over 7 oz/sq ft loading with a BP21 and 8x6 at around 200 watts. Looks like if I don't fly in the wind I don't fly.

Take care and I'll put the Zippy up when I can test it with decent conditions.

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Jul 15, 2009, 02:17 AM
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davereap's Avatar
High winds are a pain..we have them here today worse than yesterday 20 mph forecast..best in wind is to fly heavy with a slightly more forward COG than normal..

I am thinking of modding the Nifty with a different tip fin, something that puts a better fence on the ends of the wing, and something strong enough to take landing on. Its me nit picking again, I want to be able to fly at almost zero speed with a stable high alpha.. I can do that with a nutball, The nifty is almost doing it but is not quite there yet..

Possibilities Correx or two layers of 6mm depron this shape 6" in total height. With symetrical tips I think I might have the top half red and the botom half blue, to aid orientation

Next flight trials.. a heavy setup.. New tips and one of my epower 2215-20 with a 2200 lipo just what the parrot pilot used and more elevator travel

edit... These tips didnt work better ..see later posts
Last edited by davereap; May 07, 2010 at 05:37 AM.
Jul 15, 2009, 04:53 AM
flyin' fool
goldguy's Avatar
Got motivated today and built a Nifty. Using FFF I went a different route. Since the foam has a folded edge I used that as the LE and cut out a 24X12" platform, cutting the top and bottom at the same time. I then ran a bead of hot melt along the TE, opened up the doubled foam and pushed in a foam spar producing a fully symmetrical airfoil. Easier and quicker than the KF when working with FFF. Done in 8 minutes. Spent the next 1 hour 15 minutes adding a bottom spine, elevons, nose, fins, electric goodies and some vinyl trim. Goin' with the Emax 1600 on 3S. Ready to maiden.........will report and get pics.
Last edited by goldguy; Jul 15, 2009 at 05:07 AM.
Jul 15, 2009, 06:42 AM
Spaced Oddity.
parrot pilot's Avatar
Dave, this is the exact thing I was thinking!! When I attached my tips, I failed to see how they should hang below the wing 3/4", so mine are only 1/2 in. or so below (the thickness of the balsa corner support I added). I assume you are thinking about centering them(?). I was thinking that they would help with my rough landing field as well with plastic skids on the edge.
It just struck me that I could make them slightly thicker and hollow with those thin plastic wheels; 4 of them, then I could use the paved road as a landing strip! Hmmmm.
Dave, when you give COG in percentages, are you figuring using the wing and alervons, or just the wing? I'm not convinced my COG is optimum...

I'm going for another flight today then starting on a larger version.

Using FFF I went a different route. Since the foam has a folded edge I used that as the LE and cut out a 24X12" platform, cutting the top and bottom at the same time. I then ran a bead of hot melt along the TE, opened up the doubled foam and pushed in a foam spar producing a fully symmetrical airfoil. Easier and quicker than the KF when working with FFF.
Good point Goldguy; with FFF the building techniques are different. I'm sure that a 3 layer FFF wing is easily strong enough to work without the balsa spars, and the balsa fuselage I used is definitely overkill, although I am happy with the light ply nose I made. I'm sure I could make a Nifty quite larger at the same weight I'm at now. With the motor I have even several extra ounces would be OK. I'm looking for stable and durable with better than fair speed (I have 2 left thumbs). I also got a folding prop yesterday...LOL
Jul 15, 2009, 06:53 AM
Spaced Oddity.
parrot pilot's Avatar
One other thought Dave, that about rudders on the ends of the wing tips??
Jul 15, 2009, 11:02 AM
Registered User
davereap's Avatar
Dan Percentages for COG...include the ailerons...a 36" span x 18 deep would give 4.5 sq ft and lower your wing loading a lot..

Wingtips, Ive not thought of rudders, but what ive now done is made the tips to the new shape using 2 layers of 6mm depon..they were made 5.5" deep.. and the slope at the front is 30 degrees. The tips are fitted centrally to the wing..ive also fitted one of the more powerfull 2215-20 motors which should take it to Warp 2..
The AUW is 17.5oz and thrust is 34+ oz....wing loading up at 4.9ozsqft
The COG is still easily obtainable with the 1250 lipo.. as in the pictures
I still have to adjust the elevator to get some additional movement for the slow flight
Goldguy It will be interesting to see how the symetrical section flies when compared to the KFm4..and see if the best flying COG's match up.. It certainly made for a faster build..

Anyone for combat ..use the large motor it should work much like a circular saw
Last edited by davereap; Jul 15, 2009 at 04:43 PM.
Jul 16, 2009, 05:58 AM
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Nice day today with more bad weather tomorrow so Ive just run two batteries through the beast...
results... the bigger motor gives more go..the low middle to top end flying is smooth, rolls are axial loops tight. At this end of the speed range I think the heavier setup is slightly better
Increasing the elevator has tightened the loops but not helped the very slow end flight at all. If anything the increased elevator will let you over control..I went up from 80% to 120% movement ..Neither has the altered shape of the wing tips made a difference to the slow flight.
Now is that because ive gone with a heavier motor and tips at 2..25oz heavier, I am not sure so I will return to the original motor for the next trial..

COG issues... I felt that the on this setup motor and or tips..I was too far back at 22% and in the end 18-20 felt nicer for the flying, although the glide was better at 22.
Very slow flight.. It will go very slow but doesnt harier well, it does a quick nodding movement as it looses height but unlike the previous nice parachute this one had the nod in it.. so I think the extra weight or the extra elevator movement is making a difference.
Normal slow flight..just pottering around... again it was ok, but again I felt the additional weight has made it a fraction poorer at these speeds compared to the first setup
Wingtip shape... the different tips havnt helped the ultra slow flight at this flying weight.. But they do make a difference to the way the plane tracks through the air at speed... its not a problem it just feels different when you fly it..

conclusion... the first setup is the prefered one so far

now to change the motor back and try again..
going back to the original motor shows the different tips have added 1.5 oz to the build..so they might have to be cut down or changed back
Last edited by davereap; Jul 16, 2009 at 06:24 AM.
Jul 16, 2009, 07:03 AM
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Another flight with the lighter motor, back at 22%......its getting windier out there and I think the larger tip fins are weathercocking or something.. so out comes the knife chop chop and I now have an all up weight of 16.25, still 1 oz over the original and the fins are reshaped...more of a slope at the front and the bottom half cut down all the way along.

To be honest the first original shape is ok, but I would mount the fin a bit more centrally..perhaps 1/4 area below the wing acting as a fence.

Ok next flight wind now up a fair old bit.. This felt better so it was the large tips causing some weathercocking... A bit more taken off and it will be perfect again...

This little wing sure does wizz about, I was doing some high speed runs when this solid square metal football goal post just jumped out from nowhere and hammered the wing to a stop

Here is the damage shown on the LE of the wing. the battery had come off and unpluged itself, all to the good... so I restarted and carried on flying.. no problem.. As ive said before using the tape makes a very strong wing.. If this had been a balsa model I would be rebuilding, as it is its battle damaged but otherwise fine

I will now try some boiling water to see if any of the damage will come out.. No that didnt completely work..oh well its a bit better but still there
Last edited by davereap; Feb 20, 2011 at 04:34 PM.
Jul 16, 2009, 08:06 AM
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I think after going around in a circle..sort of, with setups... the first setup is the nicest..
All I would do is to position the tips with increased area below the wing to act as more of a fence, and if you are into heavy collisions a CF rod down the LE will make it even stronger, spreading any impact loads...
mind you hitting that metal goal post might well have shattered the rod
Jul 18, 2009, 05:15 AM
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Ive been chopping the fins down some more.. there is now 2" height above the back of the wing and 1" below..thats measured where the wing is just one layer behind the step..the top front slope starts fron the step position, going down to the LE..the bottom slope is at the same angle, but meets the bottom edge about half way back to the step
The AUW with the double thick tips is 16.25 oz this includes the 4oz battery....for a wing loading of 4.6ozsqft..
My preference is this setup for its all round performance...however for speed freaks a bigger and higher kv motor, and a heavier auw will make a rocket out of the wing , but the very slow speed will be poorer

present setup...32" span at 16.25oz... 1250 3 cell rhino..9x5 gws prop... this motor http://www.overlander.co.uk/product....id=93&pid=2581
.. 9gm servos ...max draw 15A... nice 1/2 power cruise or full power wizz... this motor has 24oz thrust at max power
Last edited by davereap; Jul 18, 2009 at 05:27 AM.
Jul 18, 2009, 06:18 AM
Registered User
Finished our build of the Nifty 32" yesterday. Followed your instructions, but added some counterbalance to the elevons to ease the work of our 5g servos. Used a slightly underpowered and light setup, but with it the glide was absolutely amazing, the thing just wouldn't loose height with the slightest amount of throttle applied.

360mAh Rhino 2S
Turnigy 2730 1500kv
GWS 8x4 prop
TowerPro 9g w12A ESC
HXT500 5g servos

Our COG was way back due to the light equipment hence it turned out to be rather sensitive with crazy manouverability. It flew great still and we just might build a couple more. Thanks for the making this simple, but solid plan.

Will try with a 1000mAh 2S today for better COG. Might also try with a gyro attached.
Jul 18, 2009, 07:26 AM
“There’s no place like Foam”
gpw's Avatar
Dave , years ago we had a plank with HUGE square tip fins ,and it was Crazy stable ... any turn , and you had to hold the stick in or it would automatically right itself... somewhat unnerving.. till you got accustomed to it... Odd how fin size makes such a difference...
Jul 18, 2009, 09:10 AM
Registered User
davereap's Avatar
I am pleased you enjoyed it.. a few questions on your setup...what size did you build, what material did you use, and what was your flying weight and COG locaton when you flew....all info that will help others to choose their setup.....and please post pics of your decoration...
The tips make a lot of difference, like how it tracks when its banked well over etc.. but I didnt notice any self righting on mine.. With the COG correct it just goes where you point it, which is nice. It also rolls axialy when that COG is correct..

Another thing I am liking is the wing seems to fly at a fairly steady top speed that is most dependant on the motor power/revs.. If you go down in a dive it doesnt get away from you, not gaining much extra speed.. It lets you fly powered up right through the loops which you can make as big as you like..
Last edited by davereap; Jul 18, 2009 at 09:19 AM.
Jul 18, 2009, 09:17 AM
John 3:16
Daddy-O's Avatar
It would be interesting if someone would build this with 1" to 2" dihedral. It would be interesting see how different the flying characteristics would be. More stable...self righting...easier for newer pilots?
Jul 18, 2009, 09:21 AM
“There’s no place like Foam”
gpw's Avatar
Dave try fixing some Large temporary fins to it(cellophane tape ) , and mostly above the wing to experience the self righting tendency ... easily removed for normal flying ..

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