Fanfold Su-27 Flanker - RC Groups
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Mar 07, 2003, 06:22 PM
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Thomas Nelson's Avatar

Fanfold Su-27 Flanker


AUW: 18.2 ounces
WS: 24"
Materials: Fanfold airframe, Hollow EPP nosecone, Posterboard canopy.
Mega 16/15/5 brushless motor
Prop: 7x5E APC
ESC: Castle Creations Phoenix 25
9 950 KAN NiMH cells
Loosely based on a Fiddlers Green paper airplane plan

Flight Envelope ranges from about 20 mph high-alpha to 50 mph on the level - this is an eyeballed estimate. I have up to 5 minutes of unlimited vertical on this combination, and over 7 minutes of total airtime.

Here's a video of this setup in action over the Okanogan Lake:

Here's another from my favorite site in Calgary:

Follow this thread to see more video of this plane on super duper Lithium Polymer power.

This is the third Flanker I've built. The first was a Power Scale Soarer (PSS) with a 44" wingspan; balsa and blue foam. The second was a fanfold Speed 480 prototype, which was a testbed for this brushless bird.

To the casual observer, the brushed and brushless might seem to be the 'same'. But I went to some trouble to make this latest '27 much more scale. I'll add pictures as I get them, and add some video shortly.

Guess where I took this picture? I wanted to give an idea of the relative size of the plane.
Last edited by Thomas Nelson; Jan 12, 2004 at 08:34 PM.
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Mar 07, 2003, 06:32 PM
smug in granny panties
monkamarm2000's Avatar


Let's see, do we get a courtesy flush? LOL Plane looks nice, I dig it. And I still love the 5T bigger prop idea. Can't wait to get my 6T Zero going.

Mar 07, 2003, 06:33 PM
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Thomas Nelson's Avatar

Motor Mount

The motor mount is obviously unfinished. It's very close to the final thrustline, but I want a couple more flights before I commit - only two so far. Once I've decided there's no more need for testing, I'll trim the balsa rails to a more scale profile, and paint them.

As it stands, there is zero left/right thrust, and a "bit" of downthrust (pushing the tail down - am I using the term correctly??)
Last edited by Thomas Nelson; Mar 07, 2003 at 06:35 PM.
Mar 07, 2003, 06:47 PM
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Canopy Hold Down Method

The canopy is made from poster board with the paper peeled off, of course. It can be rolled very easily in one direction. The trick, though, is trying to figure out the two dimensional shape that will result in an appropriate three-dee shape. I shamelessly stole the 'gist' of the shape from a rubber-powered design by Howard Metcalf. It was a free plan some two years ago. This canopy shape is MUCH more realistic than the Fiddlers Green attempt. Not to knock Fiddlers Green, though ... they never intended their designs to be blown up a gazillion percent and scrutinized by the RC community.

The hold down method uses a carbon push-rod, glued to a balsa block which is, in turn, glued to the inside of the canopy. The rod is nearly flush with the front and back of the canopy. This ensures that the canopy is held DOWN at the front and back.

To install, slide the rear carbon piece under the rear of the hatch. Slide the canopy all the way back until the front carbon piece clears the front of the hatch. Then slide forward.

Light, simple, spring-loaded and leaves the interior of the hatch uncluttered with rubber bands or mechanisms. I've used this method on two planes now. First saw it on my Multiplex Lucky Slope Soarer.
Last edited by Thomas Nelson; Mar 07, 2003 at 07:41 PM.
Mar 07, 2003, 06:59 PM
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Handlaunching, the antenna and the ESC

This was an important goal of mine - I wanted an EASY to launch plane. Choosing a pusher helps (over an EDF, that is), but the Flanker has such wide nacelles, that grasping it is difficult. The interim solution is a balsa block directly under the CG. Index finger gives the fling needed.

Not that it needs much. The large prop generates nearly 22 ounces (poor mans measurement) of static thrust, and the plane weighs 18 ounces, so just a mild toss gets 'er going. It needs zero time to 'get on step'. It's funny, but I really expected that I'd need more static thrust before I would get vertical performance. Actually I was saving my 8x3.8 prop for that, since it generates some 28 ounces of static. So imagine my surprise when I pulled vertical 'just to see', and watched the Flanker just keep on climbing!

Also visible is the CC 25 speed controller. I faired it in the lower 'spine blister'. The scale enthusiasts will notice that I've lengthened this blister so as to also enclose the wiring before it enters the fuse from below. I wanted the ESC to be 'in the breeze' because I anticipated lots of part throttle and, therefore, lots of heat.

Finally, the antenna is visible as it runs along the CF reinforcement of the right wing.
Last edited by Thomas Nelson; Mar 11, 2003 at 07:50 PM.
Mar 07, 2003, 07:12 PM
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The stabilators are actuated by one servo each. Both pitch and roll are exclusively controlled by the stabs - no ailerons or flaps.

They pivot on concentric aluminum tubes that run completely through the each nacelle. Easy. The ducted fan guys can eat their heart out.

I chose a (nearly) aerodynamically balanced pivot location on the prototype and was not satisfied with the roll authority. So on this bird I went with Sukhoi's pivot location, which leaves tons more of the rear of the stab in the airflow than the front. But this works MUCH better. Lots of roll and pitch control now - even at the relatively slow speeds this flies at. Visible in other pictures is the CF reinforcement between the front and rear portions of each stab ... NO chance they'll break from flight loads.

Of course, my concern all along was overloading the servo. No indication so far ... we'll see!

Also visible is a little scale detail that my PSS bird also has: the full scale stab actuator faring is reproduced in Fanfold. Kind of ridiculous on a mere foamie, but it wasn't hard to do.
Last edited by Thomas Nelson; Jul 25, 2003 at 01:15 PM.
Mar 07, 2003, 07:17 PM
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Landing Gear blisters

I spent some time planning the rudder-to-ventral-to-landing gear blister transition pieces. Spent too long on this, actually. But the next one (Russain Knights scheme) will be much faster as a result.
Last edited by Thomas Nelson; Mar 07, 2003 at 07:46 PM.
Mar 07, 2003, 07:21 PM
Tim H.'s Avatar
Wow, Wow, Wow! I've been hoping you would begin posting pics. I think it's time to get the Fan Fold out again!

Outstanding job! Get some video soon...

Tim H.
Mar 07, 2003, 07:24 PM
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Ralph A. D'Amelio's Avatar
Absolutly fantastic Bravo Thonas. The flight envelope is exactly what I want and I am sure others as well.

Now where are the plans and construction article. Ralph
Mar 07, 2003, 07:26 PM
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Front Three Quarter view

The wing is a single thickness of fanfold. My brushed prototype used fiber reinforced tape for strength, but I wanted something better for the brushless bird.

This plane used a 0.007" carbon fiber shear web, layed into the wing at the high point. Works very nicely; strong with some give. Toughness and CF don't often go hand in hand, but using carbon in a shear only application comes close.

The "airfoul" is simply eyeballed. I sanded a flat bottomed shape at the tip and simply carried the shape inward toward the rudders. This worked surprisingly well on the brushed version, and I saw no reason to complicate things for the Mega powered '27. It keeps the wing thickness nearer the scale thickness, since any "real" airfoil will be much, much thicker, draggier and difficult to disguise at the root/fuse area.

I've flown RC sailplanes for 12 years, so this airfoil approach really did cause me some physical pain. But it works, it's light and easy to repair, and maintains the scale lines so I opted to live with it.
Last edited by Thomas Nelson; Mar 08, 2003 at 12:57 AM.
Mar 07, 2003, 07:35 PM
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Last one ...

One more pic to round out the Flanker. Good enough for now!

As soon as the weather, cameraman and camera-availability all permit, I'll link a video.
Last edited by Thomas Nelson; Mar 10, 2003 at 06:36 PM.
Mar 10, 2003, 02:20 PM
Dude, where's My Plane?
JasonJ's Avatar
I really want to do a smaller one that can had lauch with ease, the Whole Bungee thing is a nightmare this time of year, by the time you get the steaks hammered into the ground deep enough, the bungee is cold and flacid . My next project will be a single micro fan that hopfully hand launches. I like the detail on your and the chuck blick, I cut a hole in mine in about the same spot that let me get my finger on the carbon rod that runs trhough the wings for a good hand chuck, but its jut not enough to get it in the air . Next try will eiter be with bungee or the new lipoly cells and a dolly.
Mar 10, 2003, 06:09 PM
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Thomas Nelson's Avatar

I appreciate the positive comments!

In all honesty, Ralph, I can't say that I see myself as having enough time to take the templates I've made up and make plans per se. I'll probably just post the templates at some point. I would also have to get some kind of "go-ahead" from Fiddlers Green, since the upper fuse/turtledeck borrows heavily from their paper plane design. Not likely to happen soon, I'm afraid.

And any contstruction article would really be a 'how to' for fanfold. Once the pieces are cut and formed, do what comes naturally! One thing I'll do next time is pre-tint the spackle "fanfold-blue". Just recently read where others are doing this very thing. The only place I needed any was along the fuse-lex seam, and I wasn't satisfied with how the water color paint concealed this.

Weather is supposed to peak above freezing later this week, so (hopefully) some digital video will be available by the weekend, Tim ... stay tuned!

And I hear you, Jason. My thermal sailplanes use an electric winch to get up to 'thermal chasing' height. It's a pain to set up and tear down, and requires a lot of real estate - I'm sure that an EDF bungee is the same. My favorite flying site is overlooking a valley, and allows me to toss into winds from ENE, E, SE, S, SW, W, WNW. Very scenic and close to home, BUT no room for a bungee (or winch, for that matter). So a handlaunch-capable plane was a given.

Jason - are you saying you've had your two-holer up already??
Last edited by Thomas Nelson; Mar 30, 2003 at 06:47 PM.
Mar 11, 2003, 02:36 PM
Dude, where's My Plane?
JasonJ's Avatar
yeah, I had it up, and down. I could not get enough pull on the bungee, I need new Latex,,, I did a good hand launch into the wind but I aborted because of the way I had to thow it was twoards the tee line. Knocked off the nose cone. Its a though plane. I think a good bungee launch will have it up in short order. It will be a while before the field is clear of snow and not to muddy. I think Ill try the dolly ROG. I am starting work on the single S-55 with a Vasa 55 and Hacker B-20.
Mar 11, 2003, 06:06 PM
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Ralph A. D'Amelio's Avatar
Thomas could you post picture of your servo stabilator connection and where the servos are located? Heres how I mounted them in my prototype f-15

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