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Jan 15, 2004, 06:29 PM
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Thomas Nelson's Avatar

How to Make a Fanfold Flanker

F3 Sukhoi Su-27 Flanker

CAD/pdf plans as well as a pictorial guide are now available from Click the Jets page. 2004-05-29 ... tn
end Edit<

First – let me share my interest in this subject. I have a tough time moving ahead aggressively on projects that don’t get under my skin. However, with the F3 Su-27, several key factors kept me motivated, and I’d like to pay my respects:

Nigel Hawes free “Hawker Hunter 400” design (ezone) provided inspiration:
  • Proof that a 20-ounce AUW yields reasonable performance on a single Speed 400 system.
  • 9-cells on a Speed 400 work well. And consider the option of upgrading to a brushless system on 8, or even 7 cells. Meaning 2 – 3 ounce AUW reduction over a brushed system, with FAR superior thrust/weight ratio!
  • Flat plate wing, sanded to THIN ‘generic’ profile – light & easy to make & repair, yet provides sufficient lift for a 20 oz AUW airframe.

Flat Plate Techtonics article in the August 2001 Flying Models magazine by Brian Steele, in collaboration with Keith Shaw:
  • Light, simple and repairable Flat Plate wing (no airfoil at all) flies well so long as A of A is kept under control. In other words, non “jet- like” maneuvers need not apply.
  • 17oz all up weight for excellent Speed 400 performance. These planes were based on 7 cells, but I used 9 cells yielding a 19 oz AUW.
  • 1100 mAh for reasonable flight times with throttle management.

Fiddlers Green paper airplanes. Their paper designs kick started the shapes I eventually settled on. While my templates differ significantly from theirs, there is little likelihood I'd have thought to even try the approach they do with paper. Chip Fyn of Fiddlers Green was kind enough to allow me to reprint the modified templates - in case anyone wonders - provided no money changes hands.

Can't forget about all the peeps here on ezone that answered my questions on ... everything. A great many questions were addressed via search; many here have no idea how much inspiratation their posts provided 'cause they were answering somebody else while I lurked. It's great to have a place to go to have virtually any question answered in minutes. Motivational indeed!

Finally, the REAL Sukhoi Su-27 Flanker:
  • Absolutely Intriguing airplane to look at – from any angle. Complex blending of fuse to wing to engines results in an unmistakable shape in the air. Love that dropped nose and hunched back.
  • Generous lifting area includes fuselage – easier to make a small model with low wing loading, especially with the limited lifting capability of flat plate wing construction.
  • Tail boom suitable for hiding a single pusher motor – the prop is well back of the engines, meaning the airflow to the prop is superior to mounting the motor in an engine nacelle.

So I bought the Multiplex TwinJet and confirmed for myself the potential of electrics. What an awesome way to be introduced to the world of e-powered RC aircraft! Who hasn’t been inspired by this amazing model?
  • Durable: easily repairable airframe bends rather than breaks
  • Performance: good performance per dollar. Brushless motors are not required for an exciting flight envelope.
  • Looks: the TJ has a nice shape in the air. While I was initially turned off by the “toy airplane” appearance - what with all the polystyrene beads visible up close – I soon forgave this weakness. There were just too many mitigating factors with Elapor. Just don’t stand too close when it’s on the ground!
  • Ease of Assembly: components attached with glue or tape – easy to make, upgrade and repair.
  • Size: small enough for easy transport & no pre-flight assembly required. Yet large enough to handle the wind, and it doesn’t require exotic building techniques & materials to keep light.
  • Wing Loading & Power: suitable for hand-launch – No need for the extra time, the ‘real estate’ and risks associated with a bungee launcher.
  • Relatively Draggy Airframe: eases the landing task. Easy to slow down, and likes to land nose-high.
  • Pusher Design: protects the motors(s) and maintains the appearance of the nose.
  • Well sorted-out Propulsion System: Gunther props are cheap, durable and work WELL with a Speed 400. Same with the Irvine 5x5 Carbon props. Trial & Error not required.
  • All adds up to a plane that gets FLOWN. Who’s afraid to fly their TJ even when conditions are less than perfect? Lots of flying time; very little shop time.

In spite of all this inspiration, however, numerous OTHER issues were still unresolved, even as I started building. So, the original project was to be a test-bed of new (for me) construction materials, techniques & skills. Although I’ve been flying since 1988, the only planes I flew were either thermal or slope sailplanes. Many of these were my own design. Several were scratch-built. But I realized that many of my design/building skills/techniques would not apply to fanfold. Further, I’ve only been flying electrics since June of 2002, and only the TwinJet. Some of the issues that would need to get resolved as I worked my way through the Flanker were …
  • Is Fanfold up to the task of conforming to the complex shapes of the Su-27? Would I have to slice it into half-thicknesses? How big would the plane need to be before I could reliably bend it around (say) the radius of the engine nacelles? What role does heat play? Hot water in a bathtub? Hold over a boiling kettle? Hold in an open oven?
  • Are the Fiddler’s Green paper airplane “plans” suitable for a construction medium as thick as Fanfold, and a model as complex as the Flanker?
  • Strength to weight issues of Fanfold. Once bent, folded and formed, are bulkheads, formers and stringers even needed? Is the hollow unibody-type of construction (monocoque) that comes from marrying Fanfold to FG plans suitable for this project?
  • Where to get Fanfold? No easy task in Canada!
  • What airframe size to keep within the targeted 20 oz maximum AUW? Would be nice to have around 144 square inches of wing to keep the loading under control (20 oz/sq ft).
  • What adhesives to use? I already had some 10 different types, but if the airframe ended up ‘bendy’ should I be using the heavier “Goop” types? I had never heard of Probond prior to researching the monumental Fanfold thread on Ezone; “Bought some Fanfold, now what to build?” This thread, by the way, was supremely inspirational. In fact, it’s what drove me to write this synopsis – with the thought that I might contribute in small way to someone else’s search for inspiration on their project.
  • Are humble 1100 mAh MiMH Hecells REALLY capable of providing the volts and amps needed?

Among the cool things about building with F3 is that you “see” the plane take shape almost immediately. This, too, inspires one to keep moving – even if there are upcoming stages of the project that one doesn’t yet know how to resolve.

So that’s a little bit about me, my interest in the Su-27, and what I was trying to accomplish with this design. As you can see, I have borrowed heavily from the efforts of others.

A n y w a y, my intentions for this thread are to outline how I built this, my third fanfold Flanker - and hopefully assist others to build one too!
Last edited by Thomas Nelson; May 29, 2004 at 11:58 PM.
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Jan 15, 2004, 06:46 PM
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You have MY attention! Very nice effort indeed! Let's see some more of the plane and let us know how you used your talents to get this bird together.
Jan 15, 2004, 06:47 PM
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Thomas Nelson's Avatar

Details, details

Here are the specs on my latest '27:

Scale: 1:22
Area: just over 200 square inches
WS: 24"
AUW: 18.5 ounces
Motor: Mega 16-15-5
ESC: Castle Creations Phoenix 45 (with BEC)
Cells: 4S1P ThunderPower 2100
Controls: 2 servos (HS-55) driving Tailerons (elevons subroutine on the Tx)

Prop: The Graupner CAM 5.5 x 4.3 keeps the amps happy. But these ThunderPowers cells don't deliver the watts like the last LiPoly cells I used (185 versus 210 on the CAM). SO, I expect I'll be flying a Aeronaut Carbon 6.5 x 4, which gives an estimated 1.3:1 thrust to weight (static). Amps are higer than recommended, but the plane wants to hit the ceiling at half throttle, so that's the ticket.

BLUE Fanfold construction with an EPP nose cone.
Edited 2004-02-02 ... tn (Pink is too brittle to form into the shapes needed. Be sure you use Blue fanfold for this project. Suggested thickness is 3/8", and it's looking like 1/4 should be considered a minimum, unless you wish to deviate from my approach. My foam was just under 3/8" thick).

What's it fly like?

Here's a link to the maiden flight. And here's a link to it's predecessor, which I retired this fall with 82 flights on it. The second video is not a 'new' video, so some will have already seen it. I get up to 15 minutes airtime with the thrust to weight ratio exceeding 1 at all times.

Further, those who have the free FMS (Flying Model Simulator) can download a simulator of my Flanker, which I've tweaked to mimick the flight envelope. (Many thanks to Gary Gunners for creating the simulation of the '27). The diehards out there checking into the .par file will notice that the parameters I've chosen are not "real world" ... I settled upon these parameters only because they best emulated the flight characteristics I observed. So, it's as close to "fly before you build" as you can get!

BTW, I've flown this plane/motor combo on an APC E 7 x 5 and 9 1100 Hecells as well as with the 7x5 with 9 950 KANS. Still get better than 1:1 thrust to weight, but LiPoly is the way to go. For the budget minded, however, this plane will also fly on 9 cells and a speed 400 with the Gunther prop ... that was the original combo I used as a proof of concept. Not exciting, but it gets you airborne at about 20 ounces.

One last comment about the power plant. I doubt my Next '27 will use a 5-turn Mega. Perhaps a 3 turn (maybe 4) and 3S1P cells. Tanic and iRate cells are now capable of over 20 amps each, so a 3S1P pack at 20 amps would yield 200+ watts. I'd pick an appropriate prop to fine tune the current consumption. REASON for all this:
  • 3S chargers are cheaper and easier to come by.
  • 3S1P cell pack is cheaper.
  • A lighter, cheaper Phoenix 25 would suffice and would easily handle the BEC option. As it stands with the P45, I am on the ragged edge with the BEC. I definitely do NOT have the option to add another servo for (say) flaps.
  • I'd also drop the cell capacity down to 1300 or 1500 mah, which are presently capable of some 20 amps in bursts. Besides, I find that 15 minutes of 'airshow" flight time is really too much for my nerves.

All this would drop at least 2 ounces from the AUW. Lighter means slower landings with less frequent damage. And I can then add weight in the form of finish, paint, ordinance etc without a performance penalty. About the only caveat is that the battery weight would still need to balance the plane; dropping weight up front may very well mean dropping to a lighter (Razor 2500/Hacker B20) higher kv motor at the back.
Last edited by Thomas Nelson; Feb 09, 2004 at 08:45 PM.
Jan 15, 2004, 06:48 PM
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bipeflyer's Avatar
Beautiful Thomas-glad to see you are using the RK scheme!

Jan 15, 2004, 06:52 PM
* iStar & PinkStar *
MartinChou's Avatar


Keep it up. Although I probably don't build anything like that soon (lack of skill ), I am watching. Keep us posted.

Jan 15, 2004, 06:57 PM
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bipeflyer's Avatar
OK,now we want detailed building notes/pictures please Tom,it's about time you made a full revelation..I want to build one myself!

I agree with your opinion on aesthetics, that is one beautiful looking bird from any angle..the Russki's got this one totally right!

Jan 15, 2004, 07:05 PM
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Thomas Nelson's Avatar
Originally posted by bipeflyer
Beautiful Thomas-glad to see you are using the RK scheme!

Thanks, Matt. I have a new appreciation for how much effort went into the RK paint job on your own '27. Took way longer than I figured. Really appreciated your help with the 'paint' BTW.

All will note from this pic that I haven't completely finished the landing gear blisters. Hopefully tonight.

And you'll see that I wasn't too anal about the finish on the bottom of the plane. After about 5 landings, the effort involved in a really fine paint job underneath is lost anyway. Hence I left the undersides bare fanfold. Not too far off the RK color scheme.
Last edited by Thomas Nelson; Jan 16, 2004 at 11:28 PM.
Jan 15, 2004, 07:09 PM
My cat up close
bipeflyer's Avatar
No problem! Just give me a set of those plans!
I have a giant stack of blue foam waiting for the hot wire,your model looks very cool!

Good luck with flights (though I know you don't need it!)
All the work with the paint job sure is worth it eh?
Jan 15, 2004, 07:16 PM
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Thomas Nelson's Avatar
Originally posted by bipeflyer
No problem! Just give me a set of those plans!
I have a giant stack of blue foam waiting for the hot wire,your model looks very cool!

Good luck with flights (though I know you don't need it!)
All the work with the paint job sure is worth it eh?
You got it, Matt. And I agree. They also found a striking scheme for their bird.

You can see here I have yet to make the blister at the back of the spine. Actually it's done, I just want to confirm the motor thrust angle before I glue it on.

Also, since this picture was taken, I've painted over the carbon. While still visible, it's not nearly so.
Jan 15, 2004, 07:20 PM
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Thomas Nelson's Avatar

Re: Good

Originally posted by MartinChou
Keep it up. Although I probably don't build anything like that soon (lack of skill ), I am watching. Keep us posted.

Thanks, Martin.

Given your familiarity with bending/folding sheets of foam, you'll have no trouble with the techniques. Fanfold is thicker than the posterboard you've been using, so you need to heat it some, but other than that you're already aware of what is involved.
Last edited by Thomas Nelson; Jan 15, 2004 at 11:13 PM.
Jan 15, 2004, 07:24 PM
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Thomas Nelson's Avatar
Well, it's 6:30 PM locally. So I'm off to get some supper and finish the landing gear blisters.

I'll add construction details (including video of some of the hard parts), pictures and ... wait for it ... TEMPLATES over the next few days. Maybe the first installment later tonight. In all honesty, I'm not QUITE done redrawing the templates of the two hardest parts to make. But all the rest of the templates are done.

Stay tuned.

Update 2004-01-19
There are scaling issues with the drawings and templates posted here. For that reason, you will need to enlarge or reduce your copies to the dimensions I've posted.
Last edited by Thomas Nelson; Jan 20, 2004 at 08:35 AM.
Jan 15, 2004, 07:34 PM
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very very cool plane and awsome skill,plans is what i need.
Jan 15, 2004, 08:13 PM
G G Ghost Pirates !!!
Vyceroy's Avatar
i await this one Anxiously Thomas..
Jan 15, 2004, 08:22 PM
Will work for planes
omega blood's Avatar
That looks F'ing HOT!
Jan 16, 2004, 07:20 AM
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bipeflyer's Avatar
I'm still tuned Tom! Looking forward to the templates!


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