** SpaFFFnutz - 48" Coroplast/FFF Hybrid Flying Wing ** - RC Groups
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Mar 27, 2010, 06:22 AM
jackerbes's Avatar

** SpaFFFnutz - 48" Coroplast/FFF Hybrid Flying Wing **

This thread is about a spin-off design that evolved from tony65x55's Zagnutz flying wing which is detailed in his ** Kline-Fogleman Airfoiled Flying Wing ** thread:


To avoid any further confusion as to where the SpaFFFnutz thread is and to prevent any further contamination of Tony's fine design by my tamperings, I'll hereby move SpaFFFnutz here.

That said, welcome to SpaFFFnutz land!

Last edited by jackerbes; Mar 27, 2010 at 06:58 AM.
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Mar 27, 2010, 06:38 AM
jackerbes's Avatar
In the beginning...

There is a KFm1 flying wing named Zagnutz. It is arguably one of the first Kline-Fogelman foamies to appear on rcgroups.com. It first used the KFm1 airfoil and evolved to KFm3, then KFm4. Then I made one using a piece of Corolast (corrugated plastic, think of the "Vote for..." and "For Sale by..." signs you see everywhere).

The first details about SpaFFFnutz were posted here:


That post is quoted herewith:

14 November 2009

With my full apologies to tony65x55, let me introduce you to the latest variant on the Zagnutz. I even gave it a name that is derived from it's roots:

SPAD = Simple Plastic Airplane Design, the popular Coroplast planes

FFF = Well, we all know what that is.

and I transliterated and mutated that to "SpaFFFnutz" and if the plane flies maybe I'll give it a thread of it's own.

Here are the build details for now though.

Wing span: 48"
Weight: 770 grams/27 oz.
Wing area: 377 sq. in.
Wing loading: 10.3 oz/sq. ft.

Battery: 4S A123 1100 mAh (180 grams, 13.2V nominal)

Motor: Turnigy DAT-750 brushless outrunner, 750 Kv, 80 grams, 180 Watts

Prop: Great Planes Powerflow 10x4.5 Slow Fly

ESC: Atlas Black 20A

Servos: two generic 9 gram micros

Material: Coroplast 4mm center panel sandwiched between Dow PB III FFF to make KFm4 strips. Factory folded edge of two FFF sheets was used for the leading edge of wing, no spars or other stiffening was added to the wing.

This is a fast build because the Coroplast center panel does not have any spar on it or in it.

The five sided center filler panels were added to the center of the wing, top and bottom. These extend back to the prop slot cutout. The filler panels are also PU glued to the coro for a little additional stiffening in the wing center.

With the FFF KFm strips on the top and bottom of the wing wrapping the coro back to the 50% mark, the filler panels in the center, and all of the FFF being glued to the coro for it's full contact area, the wing stiffens up nicely while still retaining some gentle spanwise flexibility. I think this wing will flex a little under load in flight but that might turn out to be a good thing.

The wing is .670" thick at the KFm strips and the wing thickness and step height is constant across the wing span. The KFm steps are about .230 high (a single layer of FFF).

The elevons were made from FFF and clear package sealing tape was used to make full length hinges. The elevons were later covered with a second layer of colored package sealing tape for additional strenghening and stiffening.

Motor was mounted with a 3/8"/9mm square stick. The square stick rests on the top of the coro center panel and is held in place by two screws from the bottom. The screws go through doubler was made from a paint stirring stick.

Coro is quite a bit heavier than FFF, it weighs 70 grams per sq. ft compared to FFF's 20 grams sq. ft. The change to coro center panel probably increased the weight of this build by 3 or 4 oz. over an all FFF build with spars. But I'll bet this build has made the center section pretty much indestructible too.

The wing is 378 sq. in., the loading is about 10.3 oz/sq. ft, and the plane will be flying at about 106 Watts per pound at full throttle.


Note added 22 March 2010 - I have added a working drawing of the SpaFFFnutz to this post, it should help with construction.


Note: Updated drawing files as of 27 March 2010 - Let me know if these are what you need or aren't working for you.


Note: Added drawing with imperial (inch) dimensions 28 March 2010.


Note: Added dimensions for center panel to drawing on 07 April 2010

Last edited by jackerbes; Aug 03, 2015 at 07:07 AM.
Mar 27, 2010, 06:39 AM
jackerbes's Avatar
One of the first flights of the SpaFFFnuzt is seen here. It is very capable of slow stable flight at low throttle. Like nearly all of the KFm4 flying wings, I think it can be easily flown by a pilot that has mastered a RET trainer. Put some power on it, and it will warm the heart of more advanced fliers too as the maneuverability improves with speed.

SpaFFFnutz 48" KFm4 Flying Wing (3 min 37 sec)

SpaFFFnutz is strong! As I acquired a gum pack camera and started flying that mounted to the wing of SpaFFFnutz, it became a major player in my first used of AP video. Lot's of fun as can be seen here:

SpaFFFnutz Demo - Air Camera View (4 min 17 sec)

Click on the More Videos From... link on those videos and you can find a number of other videos shot from SpaFFFnutz with the gum pack camera.


Note: 28 March 2010 - What the heck was I thinking! I had linked to the Zagnutz videos not the SpaFFFnutz videos. Now I have them right!
Last edited by jackerbes; Mar 28, 2010 at 07:20 PM.
Mar 27, 2010, 01:55 PM
Registered User
I need another equipment list for the SpaFFFnutz please!

Jack's list

The equipment you listed for the SpaFFFnutz is

Battery: 4S A123 1100 mAh (180 grams, 13.2V nominal)

Motor: Turnigy DAT-750 brushless outrunner, 750 Kv, 80 grams, 180 Watts

Prop: Great Planes Powerflow 10x4.5 Slow Fly

ESC: Atlas Black 20A

Servos: two generic 9 gram micros

I cannot find a Turnigy DAT_750. I think you have a "Turborix" DAT-750 and, R2Hobbies is out of stock. Can you recommend another motor?

Are you building your "A123" battery? If so, what LiPo battery would work with the new motor you're recommending?

In order to buy the correct esc, I just determinewhether the motor is brushless or not and, get a little more amperage than is listed for that particular motor, right?

As far as servos go, I only need to look to see if it is weighs 9 grams? Is there no other criteria such as length of stroke or anything.

I feel like an idiot but, I am lost as what to buy and I'd like to fly this thing soon.
Mar 27, 2010, 02:19 PM
jackerbes's Avatar
Hi Ray,

To your questions:

It is the Turborix DAT-750, I got my "T" brands mixed up. And to further the confusion, Hobby King has renamed that motor to be the Hextronik DT750, you can see it here:


Or the DT700 will work too:


Both are out of stock right now so it you order them from HK it will delay your entire order until when/if the item is ever in stock again.

If you want a recommendation for a similar motor and are going to order from Hobby King let me know and I'll recommend one that will work.

The A123 batteries I used on that have the 1100 mAh cells and the pack weighs about 175 grams. Those cells came to me cheap ($3.75 a cell) when Wal-Mart was closing out B&D VPX packs. They will cost you about three to four times that now so you'll probably want to use a 3S LiPO pack instead. Something like this in a 1800 to 2200 or so size:


It will be about the same weight as the A123 pack and that will make the CG work out about right.

The DAT-750 is rated for 18A, mine pulls up to 25A for short periods without self destructing. So for an ESC you would want one rated a little higher than 25A, like a 30 or 40 or so to give yourself a little "cushion" there. I like the Castle Creations ESCs and would use a Thunderbird 36 there.

I buy those on eBay and usually get them below retail, like about $30-40 or so. They are U.S. made and more expensive than the cheap imports.

For an HK ESC the Turnigy Plush 30 would work:


The HXT900 servo is always a good choice for servos, use them til they don't work, then throw them away and don't look back or feel bad. They are good and reliable though:


Mar 27, 2010, 05:50 PM
Registered User
doggit's Avatar
hey jack, glad you have put this on its own thread, and i have now decided to give my keselcoro a new lease of life, but was wondering what motor to use, the last time it was in the air i was using a 2600Kv himodel, but seeing your video has made me want a lower Kv motor so i can slow it down but still got loads of grunt, i am going to use my 3s 1500 mAh lipos, just got 4 more so have 8 now, also will use a 30 amp Esc and my 9 grm servos, as you said use em and bin em when they die, so was wondering what your motor recommendation is for this 32" keselcoro, as i am in the UK i will see what you recommend then see if it is available here, if not i will try to get the same spec
Mar 27, 2010, 09:23 PM
jackerbes's Avatar
I really like that DAT-750 motor but it seems to be getting hard to find. Hobby King has it in 700 and 750 Kv and is back ordered on both.

I think what makes the DAT-750 work so well is the large 40mm bell and 750 Kv. It is like it has more torque or inertia in that big bell or something. Maybe it is the Harley-Davidson of brushless motors?

It is rated at 18A max and I been pumping that much and more (in bursts) through mine for a long time and it is handling it fine. But throttle back and slowed down with the stronger slow fly props like the Great Planes Power Flow Slow Fly props, it has the low RPM power.

If you use about any 80 gram or so low Kv (750-1200 or so) motor that will run at about 20A continuous on a 3S LiPO, producing about 200 Watts of power, it should produce all the fun that most of us can handle.

I just spent 30 minutes cruising the motor listing at HK and don't see a motor that seems like a good replacement. I'll study that a little more...

The ultimate demise of the frist one was from a combination of minor cracks and cold weather brittleness in the coro. The first cracks were in the corners of the prop cutout and were from prop strikes when I didn't get off the power quick enough when it hit trees and stuff. The cracks grew over time and a large number of hard nose first impacts didn't help either. Eventually it started to break in half in flight. It was actually flapping it's wings in flight!

I'm going to slide some bamboo skewers in the corrugations around the prop slot to strengthen that area against blade strikes a little on the build I just started.

Mar 27, 2010, 09:27 PM
jackerbes's Avatar
I just posted updated drawings for the SpaFFFnutz. The parts drawing is full sized parts and I have a version of it tiled to 8 x 10 paper also for making templates.

Let me know if someone wants or needs something different on the drawings, maybe I can provide. it.

Mar 28, 2010, 02:10 AM
Registered User
SupraGo's Avatar
Check out rctimer.com. They have a couple of 750 KV motors that some people are trying as a replacement for the DT750s (supposed to be back in stock middle of next month). I'm trying 3 of them on a Tricopter if I can get the build off the ground.
Mar 28, 2010, 02:49 AM
Registered User
This is what I am about to order 3 sets of from HobbyPartz.com. This stuff can be used on my Super Cub upgrade and, hopefully for my SpaFFFnutZ.

EXI S1123 9G Micro Servo $2.88

Blue LiPo 3-Cell 2200mAh 3S1P 11.1v 30C LiPo Battery $19.70

30A Brushless ESC Speed Controller [Volcano Series] With ESC Programming Card (+$7.95) Both $18.95

Alpha 480 (1020kv) OutRunner Brushless Motor $16.70

Dynam Supermate DC6 DC Multi Function Balance Charger/Discharger 1-6 cell Lilo/LiPo/LiFe, 1 to 15 cells NiCd NiMH $34.95

We are in the process of cutting the templates for an OshKosh Special for my granddaughter. I would be glad if these same components could be used on the OshKosh also.

It just seems smart to choose builds that can all use the same components right now. Each plane will have it's own components. They will just have them in common.

I would like to know what prop to use with this motor on my SpaFFFnutZ?

The little Dynam charger above is a 12-volt machine. My Hobby Zone Super Cub also came with a 12-volt charger. But, it included an AC adapter. Can I use this AC adapter to provide me with the needed 12-volt-DC at home? I mean, 12-volt-DC is the same, whether it comes from a battery or a transformer, right?
Mar 28, 2010, 03:09 AM
Registered User
I just printed 32 pages of your tiled plans for 8X10 paper. Is this gonna work on my regular-sized 81/2 X 11 paper? This is not gonna cause me to wind up with another odd-sized plane again, is it?

I do see that each page has the 8x10 square inside the page. If this is normal, do y'all cut the 1/2-inch and 1/4-inch edges off before putting the pages together?
Mar 28, 2010, 06:42 AM
jackerbes's Avatar
The Alfa 480 will work find on the SpaFFFnutz but is too big for the OKS. I think the Alfa 300 is a good choice for the BB 33 at 35 grams, 1380 Kv, and 7A continuous. With a smaller 3S (900 or so) that will give you 70 Watts at full throttle and also make for a good throttled back slow flyer for the little lady. I'd go with the 25 gram Alfa 250 except that the Kv is a little high at 2200 Kv.


On the paper size, the 8 x 10 is so that just about any printer margin imaginable will not cut off any parts. So as long as you are not seeing any missing border lines you are OK. If you line up the sheets it should measure righ (24" half span, 5-1/2" wing tip, etc.).

I cut the top and right edge of sheet each sheet off so I can lay them with overlap and tape them into position with clear package sealing tape. Then I run pack sealing tape over each overlap on the front and back and the perimeter of each part. Then I cut those out and they are keepers, heavy enough for many uses.

I can put up a drawing with dimensions if someone wants it, I didn't think about that...

Mar 28, 2010, 07:58 AM
Hey, watch this!
Raymond-leflyr's Avatar
Originally Posted by jackerbes
I can put up a drawing with dimensions if someone wants it, I didn't think about that...


Rather than printing out the tiled pages, I think a drawing with a few dimensions would ge me started. I have tons of Coroplast left over from my SPAD days and I've been building almost exclusively with FFF for the past three years. So your design that combines the two would scratch my nostalgic itch (at one time our club had eleven Zagis).

Mar 28, 2010, 09:44 AM
jackerbes's Avatar

I'll get those up sometime today, I have the drawing done I just need to clean it up a little I think.

If you liked Zagis you'll love SpaFFFnutz. It is like a Zagi that almost anyone can fly and then when you turn up the wick a little bit it will entertain the experienced guys too.

Mar 28, 2010, 04:59 PM
Registered User
doggit's Avatar
well i finished work tonight at 7pm, and stuck and cut the plan together, then found a big bit of scrap coro, and cut out the main body, the only thing was i had a slight shortfall on the coro, so had to add about a couple of small pieces onto the wing, but as the KFM steps will go over it, it should be ok, and now i have all the bits cut out, but i will start to build on tuesday, its my last day of my shift at work tomorrow, and off for 3 days, and as the UK weather is so windy at the mo i cannot get out and maiden my 26" bluecor/depron wing and my 3rd divinity 42", so will use the time to build, and i have seen these 2 motors, do you think they will be suitable, http://www.giantcod.co.uk/keda-thumr...-p-403682.html
i have added a couple of pics of my cut out pieces, and a picture of the 2 added bits

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