**The Tuffy** Pusher type Primary Trainer by Tony65x55 - Page 11 - RC Groups
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Mar 19, 2009, 02:44 PM
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I printed out my wing plans yesterday but have been too busy to cut foam!

Hopefully tonight I can wrap things up - will post pics when I'm done!

Really looking forward to tossing this in the air!

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Mar 19, 2009, 02:59 PM
jackerbes's Avatar

My Tuffy Build, Part 5...

53 - The servo tray with DuBro #847 (20") or #852 (30") Micro Pushrods in place. As seen here, they come with all the hardware needed (except the control horns) to put the mechanical adjustments out on the tail assembly where it is quick and easy to get at for adjustments:


The 20" ones are just long enough I think, I had a set of the 30" and used those. It is easier to buy the long ones and cut them down if in doubt. The Leftover pieces of sheath and wire are always handy to have around. The sheath is flexible and is perfect for fishing antenna wires through foam passages.

54 - The receiver bay. The servo leads are seen. I'll route the aileron leads down either through or around the wing. The receiver is all that will be in there, I'm going to use Velcro and mount the ESC (Phoenix 25) on the side of the fuselage below the wing. The motor I'm using here can pull the 20-25A continuous (although I'm not likely to ever do it) and the ESC runs pretty hot with it so I'm going to put the ESC on the outside for better cooling.

55 - Servo tray in position. The push rod sheaths need to be moved back a little to allow for the servo arm throw. I tested the servos before and after installing them. There is little or no difference in the amperage the receiver and servos draw (0.08A idle, 0.016-0.018A with both traveling) as installed. That is another good use for a watt meter, watching for excessive linkage loads on servos. A wonderful tool!

56 - Close up of push rods and linkage. Barely seen up by the servo leads is the antenna wire. That goes down and into the same passage as is used by the pushrods.

57 - Pushrods and antenna exiting fuselage just above the boom. They will be brought down to the boom for prop clearance and fastened with a cable tie.

58 - Motor mount with "X" mount in place. That is 1/8" birch plywood, 2" wide and 3-1/2" tall.

59 - Back of motor mount, 4-40 tee nuts in place. Theaded holes are blocked with screws and a dab of wax so that they do not get plugged up when the motor mount is glued in place.

60 - I made a two-layer foam block and glued it on top of the fuselage to raise the fuselage until it was even with the block that is on top of the trailing edge of the wing. The block gave me a little more gluing surface so I could raise the motor mount up a little bit to get clearance for 10" props

61 - Motor mount being glued in place with 5 minute epoxy.

To be continued...

Mar 19, 2009, 03:15 PM
jackerbes's Avatar
My Tuffy Build, Part 6...

62 - Vertical stabilizer ready to be covered with colored package sealing tape. The edges have been very slightly rounded with the 80 grit side of the sanding shingle, then smoothed a little with the 100 grit side. This is just enough to break the sharp corners, I don't sand the bottom edge which will be on the boom.

63 - Lay tape on with slight over lap. I use bottom to top or back to front so that overlaps will not face the air flow.

64 - The scissor collection and snap blade knife. Putting the tape on will make you crazy if you are not using the sharpest blade in the house. And if there are any traces of glue on the edges of the scissors it will snag and rip the tape. I usually have to clean glue build up off the scissors and knife blade with alcohol several times in an evening of taping.

65 - Taped rudder is turned over, tape is trimmed to about 1/2" around. The top and left have been folded, the leading edge is ready for folding. To do that I leave the leading edge in full contact on the bench and raise the left side to pick up the tape with full contact. Go 30 or 40 degrees past vertical and stop. Bring the tape down in the center with a finger tip, then gently work to each side. If you see any wrinkles developing, slit the center of the wrinkle with the scissors and let the cut overlap at the wrinkle.

Getting tape on and down without any wrinkles is an acquired skill. I hope to attain it in another two or three years of practice. :>) Remember, we are foamies. This is about flying, the "five foot rule" is applied to all standards of appearance.

66 - On the curves, cut a series of slits in the tape keeping them at a right angle to the curve. Then fold the slits down one at a time, from front to back, and letting them overlap. The long straight cuts can be done by lifting one side of the foam and rolling it up on the tape. The point is to develop full contact slowly and full width as much as possible. Slits and cuts will minimize wrinkles.

Bubbles of air under the tape will be seen, wait a day or so and then touch the tip of the snap blade knife to any remaining bubbles and you can iron them out with a finger tip. Same for wrinkles.

67 - With first side taped and wrapped, lay strips across the other side and then turn it sticky side down. Hold the side of the blade against the straight edges, lean the knife back from vertical as far as possible, and cut the tape close to the side of the already taped edge. Restraining the tape with a finger tip as cutting helps. Make multiple passes if needed to get a full cut. That Fiskars cutting mat is a good thing. Trim around the curved edges with the scissors and press the tape down and smooth it along all edges and seams. Add bits and pieces of tape there and there as needed to patch holes and cover bare spots. Look at it from five feet away for the final inspection...

68 - Cut the rudder control surface with a vertical cut at 1-1/2" from back edge. Poke the knife tip down in to get started through the tape but lean the knife handle back and make multiple light passes against a metal straight edge to get a clean cut.

69 - Bevel from the same side on the cut edges. About 30-40 degrees is enough as that will give you plenty of surface movement. This is a good cut to practice on scrap. It will need the sharpest blade you have in the house. Get the cut started, cut slow, and keep the width of the piece that is coming off even as you cut. Use a little sawing motion on the blade to restart a cut.

If tape snags and balls up or foam balls up, your tools are not sharp enough and/or the angle of the blade is too vertical, get the blade down at a narrow angle.

70 - Now cover the beveled cut edges with tape. The cut pieces were laid, bevel up, on sticky side up pieces of tape. The tape was cut at a slight angle on the ends. Lift the back edge and slowly roll over and onto the bevel cut with gentle pressure on the cut. Slide it around on the banch to get the tape in even contact with the beveled cut. Then let it go over and flat on the bench. When you turn it back over, press the tape down in the center and several spots in each direction. Again wrinkles can slit first to minimize them. Repeat for the other part of the vstab.

To be continued...

Mar 19, 2009, 03:27 PM
jackerbes's Avatar

My Tuffy Build, Part 7...

71 - Make a full length tape hinge. With both bevels taped you'll have a tape covered "V" if you look down from the top. Lay a piece of light cardboard on top of the vstab and fold the "V" back flat on top of it. That cardboard is about the thickness of the material in a cereal box, no more than that. But it is key to the hinge working right, it gives you a slight gap between the two surfaces for when you apply the next piece of tape.

72 - Cut a piece of tape to slightly less than the full length (height actually) of the rudder. Lay the vstab on it centering on the tape. With the cardboard shim on top of the vstab, lay the rudder on the the cardboard, and bring the edges into vertical alignment. Hold that in place with one hand, lift the tape in the center with a finger tip, bring it up and over, and let it stick to the two edges. Run a finger tip across it lightly and now lay the rudder back down flat on the bench.

73 - Press the rudder gently against the vstab at the now taped beveled cuts. You will see a very narrow strip of tape visible there. It is sort of forced up and then back down into a "U" as you pressed the part together. The cardboard shim is what controls the gap and the width of the tape seen there.

In photo 73 the surfaces have not been pressed into contact yet (notice the gap at the bottom). But as soon as that is done the gap will close the tape will come up just flush with the tops of the surfaces, and you it ready for the second piece of tape that will give you a very good full length hinge.

74 - Cut another length of tape a little less than the full height of the rudder, hold both the vstab and rudder down flat against the bench, make sure the exposed strip in the gap is even, and apply the tape and the hinge is done. Check for movement, do not be concerned if there is a "stop" at about 30-40 degrees of so when deflected to the side where the bevels meet. That will be "*plenty* of travel.

75 - Cut the elevator, bevel cut it (bevels on the bottom), tape the beveled cuts, and make the full length tape hinge the same way as was described for rudder.

To be continued...

Mar 19, 2009, 03:58 PM
jackerbes's Avatar

My Tuffy Build, Part 8...

Note! The pre-taped, hot glued together, tail assembly described below came apart in flight (the hot glue lost it's grip on the tape and just popped off) on a cold day (40F or so). I'm not going to use that technique any more!

76 - I'm making an assembly out of the vstab and hstab that will slide over the boom in one piece. The two pieces of foam seen here will be hot glued vertically to the top of the hstab to form the sides of the "box" that the boom will slide into. Those pieces are about 7/8" high, 4-1/4" long, and have an angle on one end that matches the leading edge of the rudder. The one is wrapped with tape and the other is ready to be taped.

77 - Scraps from making the boom are held in place with a rubber band, centered and aligned. That will be used to make sure the two vertical side of the box are positioned right.

78 - Verticals hot glued in place. Glue bead was not "stingy" and is only along the outside edges. I have had good luck with the survivability of assemblies made from tape covered foam that are hot glued together. I have generally had to destroy the shape and character of the foam to break the weld.

I've had a couple of pieces that "popped" the hot glued joint cleanly and came off when they were hit hard in sub freezing weather. Those were glued a little on the "skimpy" side as far as the size of the bead and the contact on the tape. I've had good luck with hot gluing tape covered foam on several other planes, I'm going to continue to consider that hot gluing those is a good technique until I learn otherwise.

79 - The vstab is only about 0.235" thick and mounts in a slot (a top the boom) that is 3/8" (.375") wide so I made foam shim to fill the gap. That will displace the vstab to one side of the centerline a little but I'm OK with that (it was easier than making two thinner shims).

80 - I cut a piece of foam in half the thin way and sanded it thinner and flat on 80 grit sandpaper until it just filled the gap between the vstab and the side of the box as seen in the photo. I trimmed it to match the angle and height of the box. The vstab and box are not in their right position as seen there, the vstab will have to slide forward some to clear the elevator's travel.

81 - The shim will be placed here. It was taped to the side of the vstab in the position seen there with the colored tape. Then it was hot glued to the top of the vertical box side as seen there.

82 - The vstab and vertical box side were hot glued on the opposite side also and that completed the slide on tail assembly.

83 - The moment of truth produced a nice snug sliding fit, I think it's going to work. My latest invention for the heavy thumbed flier. The Frangible, Easily Replaced, Tail Assembly.

To be continued...

Last edited by jackerbes; Mar 29, 2009 at 04:20 PM. Reason: Point out construction flaw (in red)
Mar 19, 2009, 04:04 PM
jackerbes's Avatar

Here's a look at the Tuffy...

Here it is as of today...

Next I'll cover the fuselage with tape, then find the CG with the motor and battery mounted.

Mar 19, 2009, 04:38 PM
Geaux Saints
Hopalong X's Avatar


The tail assembly makes a lot more sense now. LOL
You need TWO pieces to make the box. Pic #78.

With that motor you have we will have to call yours: SST


Part 5-8 added to sticky.
Last edited by Hopalong X; Mar 19, 2009 at 04:47 PM.
Mar 19, 2009, 08:31 PM
jackerbes's Avatar

Thanks for your prompt and efficient service Sir!

"..You need TWO pieces to make the box. Pic #78.

You're right, I should have called it a "U shaped channel", right?

Another nice thing about that kind of tail assembly is that you can have a spare waiting in the wings.

As for the motor, I'm going to get a bad reputation here if I'm not careful. The 24 gram BW lovers will have me run out of town for being a hot rodder.

My motor choices came down to a 100 gram Atlas 2909/20 or a 63 gram 2409-12 and I decided the Atlas would balance the 4S A123 pack I intend to use a little better.

The Atlas is capable of about 250 watts continuous but I doubt I will ever use it there. And I'll set a throttle travel limit to make *sure* that it does not when certain people in my life fly it. :>)

I have this love for bigger props turning slower, it just makes me feel good. :>) I'm thinking with a nominal 10-11V from the 4S A123, this thing will fly very nicely at around 5A or 60 watts.

But we'll see how it goes...

Last edited by jackerbes; Mar 19, 2009 at 08:36 PM.
Mar 20, 2009, 06:29 AM
Registered User
Jack, I'm normally build and fly park jets but this bird of yours is is a very nice build. I have been looking for a nice trainer for the guys at work who want to learn to fly. They watch me at lunch but of course the aren't gunna start with a Mig 29 and to tell the truth sometimes its nice just to putt around for a while! Great craftsmanship.....I'll just follow along ifin ya don't mind

Mar 20, 2009, 08:14 AM
jackerbes's Avatar
You're more than welcome to do that Paul. I've learned so much here in the last year and just want to give something back.

I'm just hoping it flies well, something like the plane you want. My son and grandson would both enjoy some stick time on a stable flier like that. And is about right for my thumbs and eyes.

I started flying last spring and am just about "barely adept" at it. I've started flying a Sky Fly RTF and then moved on to a couple of Blu-Baby 33 RET trainers. I think I'm ready for a aileron trainer and hope that is what the Tuffy works out to be.

The 1" dihedral will take some of the aileron response out but it should work well enough to get me through the learning curve.

I had to order a pair of bearings for the motor and won't have those until early next week so hope to be able to maiden it next weekend maybe. I left that motor in a pond for an overnight soaking last summer and, although I was able to save the motor and electronics, I think a little water seeped into one of the sealed bearings as it was getting noisy.

Mar 21, 2009, 01:17 AM
jackerbes's Avatar

My Tuffy Build, Part 9...

84 - Taping the fuselage. Take a wrap of tape around the fuselage with about 3/4" of it sticking up beyond the side. Make scissor slits at the corners and along the side and fold the tape down. At the curves, more and narrower slits are cut. Work from back to front and as you pull each piece of tape down just let it over lap the last piece.

I didn't mention it but I sprayed a light coat of 3M 77 aerosol contact adhesive on the exterior of the fuselage and boom before they were covered with tape. I let that set overnight and then did the taping. That really improves the bond between the colored tape and the bare foam of the fuselage

Do the other side the same way, that will have the full width of the fuselage tape covered all the way around. I left the plywood motor mount uncovered.

85 - Make long vertical runs to cover the sides, each with a little overlap. With the fuselage laying flat, trim the tape flush to the fuselage all the way around. I open the 1/4" holes for the wing hold down dowels and the servo box with an eXacto knive. In the servo box I cut flaps and fold them in. I'll put tape over the servo opening when I'm ready to fly it.

I drilled the holes for the wing hold down dowels with a 1/4" tube drill. I located them directly below the leading and trailing edges and 1-1/4" down.

86 - Rudder and elevator linkages. The DuBro Micro Push Rods and Mini EZ connectors were used. The Mini EZ connectors are seen here.

87 - The 2-56 screws that lock the rods in the connectors get a dab of non-hardening Permatex gasket adhesive on them and are put in place. That will keep the screws from falling out when loosened or if they come loose. I never loosen those locking screws more than two turns and the Permatex keeps them in place. I hate messing around with screws that small in the field.

88 - I used DuBro #107 1/2A Control Horns. They come with screws and backing plates and are the right size for this plane. I put a wrap of double sided tape around the horn and get it located on the rudder (seen laying horizontally here). Get the holes in the horn directly above the hinge line with the rudder centered. The double sided tape will let you temporarily mount both horns to check for clearance and travel. Angle the rudder horn down just a little so the push rod meets it at a right angle.

Take a Tee pin and push it through the double sided tape and one of the holes on the horn to mark a screw location. Poke it through the tape covering and all the way through the foam. Remove the horn and use a 1/16" drill to open the hole up a little. Take the double sided tape off of the horn now.

89 - Put the horn back and push one screw into the pin hole turning it with a screwdriver as you do that. It will screw itself through and come out a couple of turns on the back as seen here. Push a Tee pin through the other hole, open it up with the drill, and put the screw in as before.

Hold the backing plates against the screw ends and turn the screws to engage the backing plate. Screw the screws in until the screw is just short of flush with plate. The length of the screws on those is perfect for one layer of FFF covered with 2.2 mil colored tape.

90 - The elevator horn fitted and push rod laying next to it. The push rod sheath is too long as seen there. The tail assembly is hot glued to the boom, then the push rod sheaths were evened up at the servos and pulled back enough to allow the servo arms to make full travel without hitting the sheath.

91 - Both horns mounted. The rudder horn has a slight downward angle to meet the push rod in a straight line as it comes aft and curves up. The sheaths need to be shortened at the horns to allow full travel there too. You can shorten them with the wire in them by holding a razor blade on the sheath and rotating it. Then slide the cut piece off (keep the scrap piece).

The Mini EZ connectors need to be assembled once off of the plane to "break in" that little black hard rubber retainer. It is tough to get on and off the first time. Assemble it, disassemble it, and then put it in the horn. When you mount it you can squeeze the retainer on enough with your fingers to get it to stay in place but will have to squeeze it with a pliers to get it all the way on. They don't come off by accident and are very positive and free of play. This is a very good push rod system in my opinion.

92 - The elevator horn with the sheath shortened and the Mini EZ connector fitted. I wanted the push rod between the horn and vstab so the screw is on the back side as it is seen there. I shortened the bottom of the rudder (quick cut with a razor knife) so I can get at the Mini EZ locking screw OK with a screwdriver in the field. The sheath is taped to the side of the tail assembly to immobilize the sheath for testing.

93 - I also taped the sheath a the location where I'll put a cable tie eventually. The cable tie will be just snug enough to immobilize the sheaths and hold the antenna there.

94 - The rudder sheath was also shortened and taped in place for testing. Notice the slight downward angle on the rudder horn to meet the push rod.

To be continued...

Last edited by jackerbes; Mar 22, 2009 at 07:21 PM. Reason: add a comment (in blue)
Mar 21, 2009, 01:32 AM
jackerbes's Avatar

My Tuffy Build, Part 10...

95 - Watt's Up used for testing. The receiver and servos drew 0.08A idle, that momentarily went as high as 0.33A when I moved both servos to max travel and held them there (full rudder and elevator simultaneously). It peaked and then fell back to the 0.08A so the servos are working fine and there is no excessive loads from stalls or binding.

Full travel on both surfaces looked great. I have the push rods in the servos on the last (5th) hole away. The 6th hole was snipped off of both arms for clearance between the two arms. I am using the 3rd hole out on the control horns so I can move the Mini EZ connector in one or two holes to increase the rudder and elevator throw if I need it. But it is unlikely to be necessary.

The DuBro Micro rods worked out great, the 20" length is the one to get is just needs a little trimmed off. And they are absolutely free of any play, very nice.

I cut the ends of the push rods off about 1/2" beyond the horns with the diagonal cutters. Hold the cutoff piece as you snip that or it will become a *dangerous* missile. I used a cutting disc on the Dremel too to blunt the end of the cut wire to a full flat face (that is .031" or 1/32" wire and will pierce people and things easily). The next time I have the push rods out of their sheaths I'll use a small India stone to smooth the sharp edges on the ends of the wire before I put them back in the sheaths. If you don't do that, and if the wire has a sharp edge, it will snag on the inside of the sheath as it is being replaced and goes through a curve.

97 - The tail skid. I cut one of these and it was 0 (zero) grams so I cut another one and made a two layer skid. That was laminated with Quick PU and wrapped with tape. It was only 1 gram after taping. I hot glued that in place, then I hot glued a piece of heavy duty weed wacker line to the skid to take the wear. It will look better after I drag it around in the dirt a little. :>) I also taped a piece of the push rod sheath scrap to the side of the skid and ran the antenna through that. It is just the right size for that.

98 - Got the motor and wing on, and moved the battery around on the nose, holding it on with masking tape, to get the CG right. Then I masked off the top of the fuselage and laid out the cut for the battery.

99 - I cut the masking tape and fuselage covering with a Exacto knife, then made a series of over lapping 5/8" tube drill cuts to a little less than the needed depth. Some of the big chunks came out with the drill, the rest were picked off with a needle nosed pliers to leave a rough opening.

100 - Then I went at it with the Dremel tool and a coarse, ball ended, wood routing cutter. The foam cuts easy with light cuts and you just have to work carefully to keep the side and bottom pretty flat as you work.

101 - When the battery was about fitted, I used the 5/8" tube drill to bore a hole at the aft end of the battery box so that the balancing lead on the battery could go into that recess when the battery was fitted. It is done as seen here and the battery is just below flush with the top of the fuselage and has just enough end play to be tipped in and out.

I think I am going to put a Velcro strap around the fuselage and over the battery to keep the battery in place. That is kind of an eyesore but this foam is so crumbly that I can't think of a better way to do it.

102 - Tube drilled a 5/8" hole in the side of the fuselage and into the receiver box for the BEC lead. Mounted the Thunderbird 18 ESC to the side of the fuselage (will replace that with the Thunderbird 25). I'm not real crazy about the external electronics and wiring but the wiring will be neatened up and taped down a little before I fly it. Don't want it to snag on a tree branch...

103 - The receiver box with the Y-cable for the aileron servos hanging out. Tony and Foamanator really had this one well thought out, everything is in the right place. I am going to make a small passage straight up through the wing on the center line and the servo leads will drop down in and meet the Y cable without any need for more extensions.

That's a wrap for now. All I have to do now is get the aileron servos and linkages mounted on the wing and I'll be ready for the maiden. I'm still waiting for the replacement bearings for the motor so I have some time.

I got a chance to weigh it today, it is 500 grams/17.6 oz. without the batter in and 700 grams/24.7 oz. with it in. That should be pretty close to the finished weight. Just about 1-1/2 pounds with a 4S A123, the LiPO flyers should be able to get in a few ounces lighter.

I'm not putting a landing gear on it for now.

To be continued...

Last edited by jackerbes; Mar 21, 2009 at 08:40 AM.
Mar 21, 2009, 03:12 AM
Registered User
Lowflyer52's Avatar
I used 30 min epoxy to glue the stab and rudder directly onto my square CF tube. I lightly sanded and then cleaned the CF before hand. Will that be sufficient to keep them from coming loose in flight? Also, there is a significant amount of twisting motion in the tail boom section. It is straight but I am afraid the air pressure might tweak it back in forth while in the air. Has anyone had that problem? I will post some pictures tomorrow.
Mar 21, 2009, 07:51 AM
jackerbes's Avatar
I'm glad you reported that. I have a square balsa/CF laminated boom and it twists pretty easily too. I've noticed that as I've been working on the plane.

I had thought that maybe I would consider a square CF boom if I do another build but now I won't. I maybe a round, hollow, CF boom will work though. Something like 9 mm to 12 mm or so? As I visualize it now, without testing it, a round tube would resist twisting forces.

I think a little flexing in flight it will probably be OK but if it starts fluttering it will have to be fixed.

Mar 21, 2009, 10:04 AM
In Rc for a LONG TIME FFAA#1
laserman's Avatar
jack move your antenna lead to your rudder or your horizontal stab with it close to the CF tube you can get glitches as the cf tube will block the rf signals from your tx, just a noticed thi ng before i go to bed after working nights DO not run it alo ng the cf tube


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