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Old Apr 07, 2010, 05:19 PM
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northenden, manchester, england
Joined May 2009
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thanks for the heads up about epoxy, and dont even mention inverted, it is like an alien concept to me my brain doesnt work on opposites, i have tried it and totally confused myself , but i will master that dark art one day, and yeah most of that flight was 1/2 throttle, i did WOT a couple of times, and a couple of verticals, which were fun, i always like to do basic flying on my maidens, just so i get the feel for it, then after a couple of flights, i then try some rolls ect, i have ordered that mount, and took the broke one off, and will cut a plywood plate for the bottom to act as an anchor
carl
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Old Apr 07, 2010, 06:02 PM
nickeast
Stuart,FL
Joined Mar 2009
557 Posts
Jack,

Congrats you now an official international designer....

Carl,

Proper job mate..... I think that you handled the engine loss very well... wish your camera hadn't lost the landing! That is one serious motor.... could you use the aluminum
mount and brace it with a triangular corner piece of thin aluminum attached to the base and to the back of the face where the motor is mounted?

Nick
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Old Apr 07, 2010, 06:17 PM
nickeast
Stuart,FL
Joined Mar 2009
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Jack,

How do you feel about this motor?

http://www.headsuprc.com/servlet/the...lectric/Detail

Nick
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Old Apr 07, 2010, 09:33 PM
Jack
USA, ME, Ellsworth
Joined May 2008
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Quote:
Originally Posted by nickeast View Post
Jack,

How do you feel about this motor?

http://www.headsuprc.com/servlet/the...lectric/Detail
I think I'd like a little more power than that but I'm not sure you would need it. That is about a 90-140 Watt motor and I'd like something up around 175-200 or so. But 100 to 150 Watts per pound should fly the SpaFFFnutz well.

As far as the Kv, compare the 3S battery prop testing data on the 2830-11 (1150 Kv) and 2830-09 (850 Kv). Those are the same motor wound for two different Kv ratings. It gives you a great example of the difference in the versatility and range of prop choices you have between the two motors.

The 2830-09 might fly the SpaFFFnutz OK with the 10" and 11" props (both regular and slow fly) while the 2830-11 is best with the 8" to 9" regular props and I never tried those.

I haven't tried to fly the SpaFFFnutz with any props smaller than 10" because of the 750 Kv motor I had. I tried both regular and slow fly props, like 1050 and 1060 regular and 10 x 4.7 SF, and really liked the SF props better.

After flying the GWS 10 x 4.7 SF I tried the Great Planes 10 x 4.5 and haven't used any other prop since. That prop is stiffer and stronger than the GWS SF prop and it simply works better.

But don't let me talk you into or out of anything because this is one of those deals where there is still a lot to be tried and learned from.

Jack
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Old Apr 08, 2010, 01:39 PM
nickeast
Stuart,FL
Joined Mar 2009
557 Posts
Jack,

Thaks for the info.... Have a good weekend.... lots of new vids!!

Nick
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Old Apr 17, 2010, 05:55 AM
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Chalmette, Louisiana. Mostly warm, sometimes 14-feet underwater!!
Joined Jan 2010
120 Posts
Everything is cut out and roughed up. Ready to be glued.

My prop-slot does not appear to be as deep as the ones in the "build" photos, There was only 4 spaces for me to insert skewer stiffeners.

My template was not aligned with the corrugations correctly. The top cut of the prop-slot crosses over a corrugation. I shoved a couple of skewers above the slot and, hope it holds. Next time.....

Should I be looking for 3/8" spruce, basswood or what for the motor mount?

The guy at the LHS sold me Hyperion 6.0mm Short Gold wire connectors. They seem sorta heavy to me. Is this about right and, do you use them on the motor, battery, and charger? They sure seem like they'll work better than the junk that came on my Super Cub.

Jack, on one of your post you give a great description of how to make the tape hinges for a foam-to-foam set-up. Will the tape work just as well on coro-to-FFF elevon hinges?
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Old Apr 17, 2010, 07:59 AM
Jack
USA, ME, Ellsworth
Joined May 2008
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Quote:
Originally Posted by bigoledude View Post
Everything is cut out and roughed up. Ready to be glued.

My prop-slot does not appear to be as deep as the ones in the "build" photos, There was only 4 spaces for me to insert skewer stiffeners.
I cut the wing and ailerons in one piece and had not cut the ailerons off yet in the photos. So the back edge of the wing does look a little long. I'll get some more progress today I hope on the build photos.

Quote:
My template was not aligned with the corrugations correctly. The top cut of the prop-slot crosses over a corrugation. I shoved a couple of skewers above the slot and, hope it holds. Next time.....
It is painful when you miss a cut, ain't it? But the plane will fly, and like you say you'll get it right the next time.

Quote:
Should I be looking for 3/8" spruce, basswood or what for the motor mount?
Basswood or spruce is good if you have a LHS, you can use the 3/8" square carpentry trim wood from Lowes or Home Depot too. Clear pine, birch, even oak for the small piece you need, a few inches long.

Quote:
The guy at the LHS sold me Hyperion 6.0mm Short Gold wire connectors. They seem sorta heavy to me.
No way! Those are way too big. I use 3.5mm for almost everything and even some 2mm ones on smaller planes. But 3.5mm is a good all around size.

Quote:
Is this about right and, do you use them on the motor, battery, and charger? They sure seem like they'll work better than the junk that came on my Super Cub.
I'd get some smaller ones. You need a female connector on the battery and a male on the ESC's battery leads. I use Dean's Ultra but EC3 or XT60 or any similar (but not too small and light) connector will work. Pick one and stay with it for all batteries and ESCs. You can see some of the choices here:

http://www.rcdude.com/servlet/the-Co...ors/Categories

For the ESC to motor connectors, use male 3.5mm bullet on the ESC and female 3.5mm sockets on the motor.

http://www.rcdude.com/servlet/the-Co...ors/Categories

Quote:
Jack, on one of your post you give a great description of how to make the tape hinges for a foam-to-foam set-up. Will the tape work just as well on coro-to-FFF elevon hinges?
Yes, that is what I used and they stayed together throughout it all as the plane was slowly destroyed. I have never had one fail.

Because the coro is sort of open along that edge I would wrap a "U" of tape around the edge first to give me a closed, smooth, back edge. Then use the process in that figure.

Make a test hinge on some scraps first and you'll figure it out quickly. That narrow strip of exposed tape that sticks up a tiny bit and meets and adheres to the tape on the flat side is the hinge line and the secret to it all

If you cannot cut a bevel on the coro (it ain't easy to do) leave the wing edge square and cut a good 45 degree or so bevel just on the elevon so it is like this (the x's are open areas)

--------+x\
--------+xx\

The slight gap (spanned by tape from both sides and stuck together) where the single x is will be the hinge point and the down travel will be adequate. In flight you'll only use a fraction of the of travel so if you get 30 degrees down or so (up will be unlimited of course) that is plenty.

I used FFF for the elevons on the first one, I'll use either FFF or 5/32" balsa for the elevons on the build I'm doing now. Either of those will work better that coro I think but the coro may work OK too.

Jack
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Last edited by jackerbes; Apr 17, 2010 at 12:10 PM. Reason: change balsa to 5/32" from 3/32"
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Old Apr 17, 2010, 01:15 PM
Jack
USA, ME, Ellsworth
Joined May 2008
17,141 Posts
SpaFFFnutz Build Part 5 - Gluing Center Filler Panels

SpaFFFnutz Build Part 5 - Gluing Center Filler Panels

31_skewers2.jpg

We finished up putting the skewers in place as seen in this photo, those were later pushed in flush with the coro and small amount of CA was put on the exposed ends to lock them into place.

32_CFilll_cut.jpg

Two center filler panels were cut from FFF. Be careful with my drawings and dimensions on those. I have to check something there as I had to cut these twice to get them to fill the area there and come back flush with the edge of the prop slot.

33_CFilll_prep.jpg

Trace the edges of a filler, then use alcohol and 80 grit sandpaper to prep the area for gluing. Again you want good prep and full contact gluing here as these panels are a key component of the center of the wing structure.

34_CFilll_GGPU.jpg

Wipe the area clean after sanding, put the thin streams of PU on the back of the center filller at 1/2" or so spacing. Spread the PU lightly and evenly with a flexible spreader. Spritz the coro lightly with a mist of water, then spritz the glue lightly too and position it up against the KFm strips.

35_CFilll_weight.jpg

Put the other filler beneath the coro so it will not sag or bend and weight the filler that is being glued down with something.

36_CFilll_done.jpg

With Gorilla Quick PU you can unweight it in about 30 minutes and you pick any glue that oozed out along the edges off easily at that time.

Then repeat the process for the center filler on the other side.

Jack

To be continued...
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Old Apr 17, 2010, 01:28 PM
Jack
USA, ME, Ellsworth
Joined May 2008
17,141 Posts
SpaFFFnutz Build Part 6 - Cutting Elevons, Preparing for Hinging

SpaFFFnutz Build Part 6 - Cutting Elevons, Preparing for Hinging

40_elev_trim.jpg

When I cut the wing panel the elevons were cut along with it. Make a mark 1-1/4" up from the corner of the prop slot, another on the back edge at the wing tip, and draw the cutting line. I draw both lines and eyeball and measure the results before I cut to make sure they look the same.

Cutting the coro diagonally across the corrugations is a little challenging as the knife seems want to curve away as you cross the flutes diagonally.

Working in short light cuts against a straight edge works best for me. And I always try to put the straight edge on the wing (not on the elevon) in case the knife gets away on me.

41_elev_balsa_cut.jpg

The cut ailerons are seen here. You can use the coro elevons or make those out of FFF as I did on the first build. I had a piece of 5/32" x 3" x 36" balsa I wanted to use up so I'm going to try that out. I cut the balsa to length, split it, and cut two balsa elevons. If they don't work for any reason they can be easily replaced later.

42_balsa_elevon.jpg

One of the balsa elevons seen in position. They will be covered with colored package sealing tape, I don't do paint...

43_bottom_bevel.jpg

I cut a 45 degree bevel on the bottom side of the back edge of the wing to give the elevon some clearance to swing down. I'll also sand a slight angle on the matching elevon edge. I drew a cutting line and used the expensive bevel cutter seen there and it works OK. Again it is a job that can be done as well by using a utility knife carefully against a straight edge.

Again cutting on a diagonal across the flutes can be a little challenging. A practice cut on some scrap might help but if you can follow the cutting line it will be fine.

44_bevel_tape.jpg

I taped the back edge of the wing to close the open flutes or corrugations. I used white package sealing tape and a strip of it is taped down sticky side up here.

45_bevel_taping.jpg

Lay the wing centered on the tape. Pull it up and over in the center and do that in several places to each side along the length getting the slack out of the tape. Smooth the down tape forward (not side to side) and ignore any minor wrinkles. If you get a big wrinkle slit the tape and lay it flat overlapping itself. It may look bad to you up close but it won't be noticed later.

46_bevel_taped.jpg

Trim the tape even at the end, you'll notice one of those unnoticeable wrinkles there if you look close. But smooth and snug across the beveled edge is the key thing here.

OK, I'll move on to getting the elevons covered next and then we'll tackle the hinging.

We are at 295 grams/10.4 oz. on the build at this point.

I'm going to move on faster on the build now, I have not flown a SpaFFFnutz in about six weeks or more and I am starting to get the urge to get this done and in the air.

Jack

To be continued...
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Last edited by jackerbes; Apr 18, 2010 at 11:11 AM. Reason: Add the weight...
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Old Apr 18, 2010, 11:19 AM
Jack
USA, ME, Ellsworth
Joined May 2008
17,141 Posts
SpaFFFnutz Build Part 7 - Covering Elevons with Tape

SpaFFFnutz Build Part 7 - Covering Elevons with Tape

The elevons were sanded just enough to break the sharp corners and a slight (15 degree or so) angle was sanded on the edge that will meet the beveled coro edge of the wing.

If you're using FFF for the elevons the process here will be the same and I would use the contact adhesive on those too.

50_elevons_3m77.jpg

I'm going to cover the elevons with colored package sealing tape. I spray a light coat of 3M 77 on the balsa first to improve the adhesion of the tape and let that set for 30 minutes or more.

51_elev_tape_up.jpg

Put a strip of colored package sealing tape sticky side up and lay the elevon centered on it.

52_elev_tape_on.jpg

If the elevon is too wide to let you fold up the tape along the edges of the elevon, use two overlapping strips of tape.

53_tape_trim.jpg

Fold the tape over the edges and smooth it onto the balsa, trim the tape and fold in back onto the elevons using a utility knife and small scissors.

54_tape_2.jpg

With the first side taped and trimmed lay elevon that on top of another piece of tape.

55_tape_2_trim.jpg

Keep the knife down at a shallow angle and it will cut fine. Clean any glue residue from the scissors and knife occasionally to keep it from snagging the tape. Here I've trimmed the end and will fold the sides up by rolling the elevon up onto that edge.

56_elevon_taped.jpg

Finished elevon. The dark areas are where there are two or more layers of tape overlapping. It is much less noticeable in direct daylight.

Next will be to get the elevons hinged and mounted.

Jack

To be continued...
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Old Apr 18, 2010, 11:29 AM
Jack
USA, ME, Ellsworth
Joined May 2008
17,141 Posts
SpaFFFnutz Build Part 8 - Hinging the Elevons

The elevons will be hinged with full length hinges made with package sealing tape. This is the World's Best Hinging Method for foamies, I've never found a better way to do it and never had a hinge fail in service.

60_hinge_setup.jpg

The best setup is to have the wing and elevon top side up and work on the corner of a bench as seen here. That has the coro laying flat on the bench and the FFF overhanging. A small weight keeps it in place.

61_hinge_spacers.jpg

The secret to the hinging process is the spacers seen here. I use a strip of light cereal box cardboard and a metal straight edge. Those come to a total thickness of 1/16" (1.6 mm) and that thickness is what controls the gap along the hinge line.

Lay the cardboard just back from the edge and parallel with it, lay the straight edge on the cardboard to hold it in place.

62_hinge_tape1.jpg

Fold the elevon back on top of the straight edge and align it with the back edge of the wing. The wing was been slid back a little here and a strip of Duck brand standard weight package sealing tape is laid out sticky side up.

63_hinge_tape2.jpg

Bring the wing forward and down onto the tape covering a little less than half of the width. Cut the tape free on the ends and position the wing against the edge of the bench. Make sure the elevon is positioned even on the ends and in perfect vertical alignment with the back edge of the wing.

Lift the tape to vertical at the center, gently pulling the slack out, and bring it into contact with the elevon. Do that in several places along the length, then smooth those areas forward towards the leading edge with your fingers. Smooth the tape into full contact on the elevon ignoring any small wrinkles.

64_hinge_tape3.jpg

Turn the wing over (top down), unfold the elevon, and lay it flat. Use a tongue depressor with a smooth sanded edge to press the tape into contact with the elevon and wing edges and bottom of the "U" that results. The tape will adhere lightly to the bench top in the bottom of the "U" that is formed, that is OK.

65_hinge_top_tape.jpg

Turn the wing bottom down again and press the elevon lightly against the back edge of the wing. The slight gap will be the exposed sticky side of the tape that was at the bottom of the "U" in the last step. Get the gap even all the way across and use a board or something to hold the elevon in place.

Take another piece of the clear tape, align it, bring one end down onto the wing centered on the hinge line. Press it down lightly with a finger to get full contact all the way across and cut the tape.

Gently smooth the tape info full contact, work both sides of the wing and chase the tape into the "U" groove on the bottom again. any bubbles can be vented with a pin or knife tip, small wrinkles chased with a fingernail, etc.

66_hinge_deflection.jpg

As you can see there is plenty of down deflection and unlimited up deflection.

67_perfect_hinge.jpg

Held to the light you see the perfect hinge! About a 1/16" or less gap, no give or play in any direction, and 100 percent airtight and turbulence free on the top of the wing.

The wing with the elevons fitted is now at 321 grams/11.3 oz.

Jack

To be continued...
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Old Apr 21, 2010, 10:30 AM
Jack
USA, ME, Ellsworth
Joined May 2008
17,141 Posts
SpaFFFnutz Build Part 9 - Motor Mounting and Tape Covering

I'm using the Turborix DAT-750 motor from the first SpaFFFnutz again. That is an 80 gram, 750 Kv motor rated for 19A. I'm using it on 4S A123 which would be equivalent to 3S LiPO as far as voltage. With a Great Planes 10 x 4.5 slow fly prop it produced 6,600 RPM at 11V and 190 Watts at 17.3A. SpaFFFnutz very well flies at half throttle and less.

70_momo_riser.jpg

A new 4" long 3/8" square motor mount stick was used. To use the EFlite EFLM-1915 stick mount a piece of 1/16" or so tongue depressor was glued to the bottom of the motor mount to raise it up so the mount would clear the wing and slide on.

I am attaching the motor with screws because I don't think epoxy or any other glue is suitable for use on coro for this. The non-porous and flexible surface of coro is just not a good place for a glued on motor mount. I also like that the mount and motor is easily removed.

71_momo_inlet.jpg

The 4" long stick and mount was located on the center line and the outline of the stick and mount traced. I used a Dremel tool to remove the FFF down to the top of the coro (the coro was not cut) and the mount fitted. I elected to mount the motor forward as close to the trailing edge as I could.

72_momo_drilled.jpg

Two holes were drilled vertically down through the motor mount stick and through the coro. The holes were sized to work with #6 x 1" sheet metal screws.

73_momo_doubler.jpg

I made a doubler to go on the bottom from a piece of a paint stirrer (paint stores are another of the great sources for free RC building materials). The doubler spreads the clamping forces of the screws out so the FFF will not crush. The doubler will be covered with tape to match the bottom of the wing.

Next we'll cover the wing with tape...

Jack

To be continued...
////
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Old Apr 21, 2010, 08:34 PM
Jack
USA, ME, Ellsworth
Joined May 2008
17,141 Posts
SpaFFFnutz Build Part 10 - Tape Covering

SpaFFFnutz Build Part 10 - Tape Covering

Something went wrong with the photos I took while I taped the top and bottom of the wing. I lost them all.

There was not a lot of them and not a lot to be learned there. It is a case of laying on strips of tape and trimming them. I was shooting for some sky contrast and also a pattern that made the top and bottom look different. So this is what I ended up with:

76_taped_top1.jpg
76_taped_top2.jpg
77_taped_bott1.jpg

Closeup of motor mount area. Secret to trimming the tape is to use a sharp top on a snap off tip utility knife and keep it clean of glue residue. Fold the tape back on itself to make the straight trim cuts on the end. It is hard to get foam to stick to the foam at the back of the step so I trim the tape even with the wing surface at the steps.

78_taped_momo.jpg

I wrapped the red tape from the top down around onto the bottom so that the leading edge would appear as a dark color against the sky. The toughest angle for finding the SpaFFFnutz in flight is when it it flying right straight at you, it is very thin head on.

Next we'll get the electronics on and that should finish it up.

Jack

To be continued...
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Old Apr 21, 2010, 09:55 PM
Jack
USA, ME, Ellsworth
Joined May 2008
17,141 Posts
SpaFFFnutz Build Part 11 - Mounting the Hardware and Electronics

SpaFFFnutz Build Part 11 - Mounting the Hardware and Electronics

80_ESC_recvr.jpg

The ESC and receiver (Thunderbird 18 and Berg 4L) are quick and easy to mount. Both have adhesive backed Velcro loop material on their back sides, I put a couple of pieces of adhesive backed velcro loop material on the wing and stick them on.

I also drilled a small hole across the motor mount stick and put a small cable tie there to hold the motor leads down and in position.

The receiver has an Azarr mini antenna on it and that is laid out and taped down with a few pieces of clear package sealing tape. That antenna works very well, I have flown the SpaFFFnutz to heights that put it at the limits of visibility and did not have any glitches or control issues.

81_servo_cutout.jpg

I chose a servo location a little less than half the elevon length, that will be fine with the balsa elevons I am using. If you are using coro for the elevons, mount the servo so the horn is in the center of the elevon's length. If you put it close to the inboard end it will probably flutter at higher speeds.

Trace the servo shape, cut the lines in the tape, and router the FFF down just to the top of the coro (don't cut the coro). I leave the FFF and glue residue there as the hot glue will stick to it better. I get Arrow brand High Strength & Slow Setting from Lowes and use that exclusively. It is the only hot glue that I have found that sticks well to coro. If you use some of the cheap generic hot glue it will probably pop loose, if you fly in subfreezing weather it *will* pop loose.

Put a small pad of hot glue down on the coro and press the servos into it. They will be very difficult to remove. Like you may have to rip the coro or destroy the servo to get it off.

82_servo_mounted.jpg

I use DuBro 1/2-A control horns and either DuBro Micro EZ connectors or the connectors from LazerToyz on the elevons. Make sure to center the holes in the horns are directly over the hinge line. I set the linkage for a moderate elevon throw (1/2" up and down) but that will be really twitchy until you get used to it. Set 50% or so low rates and 20% or so exponential to make this a little less sensitive to control inputs until you get used to it.

Set the elevons flat for the maiden flight, no reflex is normally needed. Having moderate elevon throw is essential to being able to bring the nose up a little and fly real slow and also for doing things like the elevator maneuver. If you find it too responsive, reduce the throw at the linkage or limit servo travel on your TX. Eventually you'll want to put the the elevon deflection back though.

83_batt_strap_loc.jpg

The battery hold down strap is made from 3/4" wide sew on Velcro from the local fabric store. Cut a 6" piece and PU glue it end to end with 1" or so overlap to make a 11" or so strap that will fold back on itself and latch.

I use the Dremel tool and the long dental burr to drill holes at the ends of the slots. The I cut back and forth between the holes to make narrow slots all the way through the wing.

84_batt_strap_bott.jpg

Push the ends of the Velcro strap through from the bottom of the wing. I lay the battery on a piece of 1/4" RC foam to keep it from sliding or shifting around in flight.

86_electronics.jpg

The foam and battery in place and it's ready to fly. Oh, I forgot to put the wing tip plates on yet.

87_almost_ready.jpg

Jack
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Old Apr 23, 2010, 07:52 AM
nickeast
Stuart,FL
Joined Mar 2009
557 Posts
jackerbes,

once again an outstanding job on the build.... I think that your build logs are the best and as far as I am concerned the last word in Dow FFF construction.

Nick
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