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Author Topic: E-36 "Puzzle"  (Read 14302 times)
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Tapio Linkosalo
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« on: June 16, 2016, 09:39:09 AM »


Meet "Puzzle", my new E-36 ship. The name comes from design where the wing saddle and stub nose for motor are removable (screw on the center front fuselage). I first tried the model with shoulder wing layout, but it turned out that it did not roll left on the climb, so spiral climb was not possible. Had to switch to conventional pylon setup. Another advantage from removable wing saddle is that the the wing can be moved a little forward and aft, which enables fine-tuning the CoG.

I planned to have short stub noses to attach and change motors. Turned out that to get the CG right, I needed quite a short nose. So currently I have two plywood plates to attach the motor. One is screwed to the fuselage, the other to the motor, and padding the attachment screws between these two I can adjust the motor thrust line.

The front of the fuselage is of laser-cut 1.5mm plywood, with bulhheads of 3mm lite-ply. Pylon is of balsa and carbon. I first had the pylon cut of lite-ply, but it turned heavy and easily warped. Tailboom is home-made carbon-glassfibre tube, tapering from 12 to 6mm in diameter.

The wing is a stretched version of my LDA-P-30 -wing. Midic 309 airfoil, main spar is a carbon/glass tube, covering Oracover Air Indoor. Tailboom tube 3.5mm made by Burdov.

The motor is MultiStar V-Spec 2205 - 2350KV from HobbyKing. Current prop 7*5 APC, maybe I'll try to find a similar-sized folder later. Speed controller is Afro 20A flashed with BlHeli-software (version 1.14.6). For battery I find Turnigy 2S 300mAh 45-90C work satisfactory. This setup has 11,500RPM drawing around 12 amps, 90 watts.

Flying weight with this setup is around 140 grams.

Attached files Thumbnail(s):
E-36 "Puzzle"
E-36 "Puzzle"
E-36 "Puzzle"
E-36 "Puzzle"
E-36 "Puzzle"
E-36 "Puzzle"
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Tapio Linkosalo
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« Reply #1 on: June 16, 2016, 09:44:44 AM »

My tailplane platform was a bit tilted for left tail tilt, and a bit too low. So to fix I added another carbon plate on top of the original. This is bolted in with two bolts, so I can now add some padding between the plates and use that to adjust tail tilt.
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Re: E-36 "Puzzle"
Re: E-36 "Puzzle"
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PeeTee
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« Reply #2 on: June 16, 2016, 10:33:44 AM »

Interesting model Tapio, and a good weight. Have you tried a right glide to improve the transition?

Peter
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Tapio Linkosalo
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« Reply #3 on: June 16, 2016, 10:44:46 AM »


Not yet, the weather here in Finland has not been especially co-operative. But I hope to have one decent evening to sort the model out before the Swedish contest at the end of June.
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DerekMc
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« Reply #4 on: June 16, 2016, 11:26:49 AM »

Looks good. I look forward to the flight report.
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Tapio Linkosalo
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« Reply #5 on: June 16, 2016, 12:09:50 PM »


Initial results here. Will adjust the tilt for right glide next, also the new pylon moves the wing 5 to 10mm forward so that will reduce the decalage and hopefully improve the climb pattern.
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« Reply #6 on: June 16, 2016, 12:21:05 PM »

Tapio

Moving the pylon forward is obviously going to move the CofG back, but unless you have reduced incidence on the wing, isn't going to make an appreciable difference to the decalage. If the model is still that loopy, you may need to shim up the TE of the wing. As an embryo power flyer I've found it best to sort out the climb first, and then if the glide isn't that good add a bit of weight to the tail. A gram or so of lead, smeared with epoxy and let into the fin/boom joint is normally good enough. Minor adjustments such as that don't usually affect the climb pattern.
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Tapio Linkosalo
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« Reply #7 on: June 16, 2016, 03:34:16 PM »

Yep, sorry I did not make myself clear. I intended that while moving the CG back I would also need to retain glide stability by reducing decalage.
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airplay
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« Reply #8 on: June 16, 2016, 03:46:43 PM »

Where about have you placed CoG with this profile? Like your flex design! See you in Sweden...

Jens
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« Reply #9 on: June 16, 2016, 04:18:35 PM »

Tapio

Thanks for the explanation. Good luck in Sweden, one of these days i'll try and make the comp there.
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Tapio Linkosalo
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« Reply #10 on: June 17, 2016, 01:59:34 AM »


Current CG is 90mm back from the leading edge. The root rib is 140mm wide, so that would be 65%. However, the tips are a bit raked back, so that moves the CG forward a bit (in reference to the total wing area). The current CG is maybe a bit too forward, I would like to reduce the loopiness of the climb a bit. Glide stability seems to be sufficient, as last Saturday the tail tilt was still (falsely) for left glide, and after a deep stall at the end of the climb it only took 2 oscillations for the model to settle down to glide. So I think moving the wing 5 to 10mm forward, switching the tilt for right glide turn and re-trimming the decalage would improve model trims. It will be interesting to see if the tilt also has some impact on climb trim, maybe I need to add a little left thrust? On the other hand, my experience of trimming the "Pimenoff #18" showed that too much decalage had to be compensated with extra left thrust, so hopefully that will compensate.
 
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« Reply #11 on: June 17, 2016, 02:33:28 AM »

Tapio

The advice given to me by my power guru is that the greater the decalage the more the model is inclined to turn to the right. Also if you launch too flat, the model initially hooks to the right. All of my electric power models have a little left thrust on the motor mount (circa 1mm under the stbd mounting screws), tail tilt parallel to the inner wing panel and a small wash-in wedge on the right (starboard) inner panel. CofG with a 30-35% tailplane is normally between 70-80%. I may have a small gurney strip on one side of the tail (or t'other) depending on how the model trims out.
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john thompson
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« Reply #12 on: June 17, 2016, 04:48:55 AM »

Tapio . if you get the climb correct, but have difficulty with the glide turn , instead of using tail tilt (which may mess up the climb ) try using a drag flap on the right wing . Size about 40 x 20 mm , use blue tack as the weight, which is easily adjusted . This is an old idea , but one that I use successfully from time to time . But just because it is an old idea does not mean it is no good , just look at Peter and myself to see that old does not meaning non working !?
Hey , Peter I do cut the grass once a week ,all other matters are outside my domain and competence .
Good Luck. John
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Tapio Linkosalo
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« Reply #13 on: July 08, 2016, 09:39:31 AM »

Here is a port side image of the front fuselage. Note simple DT arrangement, there is a spring at the end of the DT line, and a large wire loop in the end goes around a shortened servo lever. This rotates anticlockwise and releases the loop at DT. Also note the motor mount, made of 1mm carbon sheet, and with three M2 bolts and nylon nuts to adjust the clearance between the plates (and thus thrust angle). I originally had two 1.5mm plywood plates to hold the motor, but these broke on a landing onto an asphalt runway. Carbon is stronger...

The front fuz is made of laser-cut 1.5mm (Finnish birch) plywood, and the three bulkheads are 3mm liteply. Tailboom attaches to a hole in the aft bulkhead, and there is a 3mm carbon cross member to attach it to fuselage sides. My first pylon was also of 3mm liteply, but it was heavy and warped. Thus the current one has two 0.5*10mm unidirectional carbon sheets to attach wing joiner to the front (2mm balsa inbetween), a 0.5*6mm carbon to support the rear wing joiner, the rest of the pylon built of balsa, and covered in 50 g/m2 glass cloth.

In Sweden, I settled for right climb-left glide -trim. It worked in a similar fashion as for a CLG - with sufficient power to keep the model banked in climb, it rolled into straight glide and then the left turned bit. But I have parts to build another Puzzle (just need to mold the tubes), so my plan is to make another one to see if also that would insist to glide to the left, and to see what trim changes would be needed for right-right pattern. I may even try to shoulder-wing setup again, to see how much down thrust would be needed to achieve the climb without looping.
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Re: E-36 "Puzzle"
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john thompson
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« Reply #14 on: July 09, 2016, 04:46:51 AM »

Tapio . I am intrigued that utilising ply for the fuselage and pylon that you got the weight down to 140 g . Could you give us a breakdown of the weights of the various components . I am always interested in different construction methods and their merits . In my experience fatter pylons are lighter and more rigid and also give more area for fixing the wing mount , this latter can flex on thinner pylons . As to extra drag well who knows . The fatter pylon on E36 's also allows the battery etc to be placed inside , thus pushing the CG higher , rather than the pendulum effect with it installed in the fuselage . Now the question is , is an higher CG better than a lower one  ? My only experience of all of this was in the late 50's when F1C weights went from 500 g to 750 g , virtually all modeller's placed the extra weight up in the pylon , rather than in the fuselage ,as the models appeared to fly better, than with the so called pendulum effect . This also raise the question of thrust lines going through , above or below the CG which does have an effect on climb stability . Mr Barker , (Well he is a bit older than me ! ) I would appreciate your comments , please . john
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Tapio Linkosalo
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« Reply #15 on: July 09, 2016, 08:45:14 AM »

Traveling today so i get to weight the components tomorrow.  But i have one set if laser cut ply parts so can get to details. My aim was to get the draggy bits to fuselage so pylon cross section would be minimal.
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« Reply #16 on: July 11, 2016, 02:13:09 PM »

Thanks for your detailed talks on your new design. Besides weights of components I hope for some hints on your homemade booms and spars. Your methods and dimensions....
Personally I feel that better wings is next step for my models.
But I also feel that the F1S/ E-36 class might benefit from some new ruling. Like German 2m RES where carbon are no do, except for tailbooms and spars .
I fear we soon buy our models from the east european suppliers... And that would kill this beginner friendly and booming class.

Jens 
 
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Tapio Linkosalo
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« Reply #17 on: July 12, 2016, 05:17:45 AM »


Breakdown of the model weights is:

- Wing 32.3g
    + wing spar tubes 4.5g each
- Wing joiners 1.0g   (3mm front, 1.5mm rear, both pultruded carbon)
- Tailplane 6.1g
- Fuselage 86.6g
   + pylon ~8g
   + motor 29.3g
   + prop 4.8g
   + speed controller 7.2g
   + timer ~3g
   + DT serv ~2g
   + ply parts for fuselage (excl. pylon) 12.9g
   + tailboom 4.5g

The battery I used was 300mAh Nanotech, 18g, so overall flying weight is 144g.

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Re: E-36 "Puzzle"
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« Reply #18 on: July 12, 2016, 06:28:42 AM »

Tapio

Thanks for the information. The ESC is surprisingly light for a 20A rating, as with cables but less bullet connectors, they are normally 18-20g & most  of this is in the cabling, Mosfets & smoothing capacitor. I'll have to order one to try out.

Peter
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Tapio Linkosalo
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« Reply #19 on: July 12, 2016, 07:26:36 AM »

It is also small footprint, but works ok for at least 12 amps of current. I measured the weight after changing the control lead to a lighter and shorter one, and soldering off the cables to the motor, as I cut off the bullets from the motor end and soldered those leads directly to the controller. The battery leads with their 2mm bullets were as original.

I do not know how the original software works, as I re-programmed this with the BlHeli "main rotor" software v.14.6. It features the governor, but is the first version with brake function also (ordinary you do not need the brake on a heli controller!) :-)
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Tapio Linkosalo
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« Reply #20 on: July 12, 2016, 08:05:29 AM »

Besides weights of components I hope for some hints on your homemade booms and spars. Your methods and dimensions....

The method is the same that I have used for 30 years now (originally developed in Savonlinna by mr. Kilpeläinen and his colleagues, and then adapted and modified by many other modelers. FWIW, Excel used to make ski poles and surf board mast with the same procedure).

First and foremost you need a tapering steel mandrel. I have heard that people have used also aluminium (golf club shaft), but the main thing is that is is constantly tapering, and smooth surface. Some scratches may be ok, if they are longitudinal. But there must be no "coca-cola bottle" shape anywhere, the tapering is a must. For these tubes I se an old mandrel, turned in the late 1970's by my clubmates, but more recently I have turned some mandrels for P-30 and F1B fuselage. After turning the shape, I have used an angle grinder with sandpaper disk and sanded lengthwise while the mandrel has been turning on the lathe, going to finer and finer paper for smoother finish.

before molding, the mandrel is waxed several layers of cardauba wax. Mold waxes are such, but I use Simoniz yellow. My can must be 20 years old. It lasts... polishing between the layers, the wax makes layers of release film to release the tubes off the mold.

I typically lay my composites between two layers of polyethylene film. Thicker than grocery bag, this can be bough at  plastic material suppliers. Onto a clear film you can use felt pens to draw the size of the composite, and cut them to final dimension before applying to the mold. For E-36 fuselage I have one layer of 100g/m2 uni-directional carbon (old russian stuff, definitely not any HD version) and some lengths of 12k carbon rowing (4 full length, plus 2 for 50% plus 2 for 25%, so at te root there are 8 rovings). The top layer of the tube is 50g/m2 glass cloth, at 45 degrees for torsional stiffness (carbon would be lighter and stiffer, but here glass will do). In the pictures you can see the glass edged with tape. It helps to keep the cloth at 45 degrees in shape, until it is wetted against the PE sheet, and then the excess plus the tape is cut away.

So I lay the carbon on the plastic, wet it with laminating epoxy, then apply glass cloth, wet some more, apply another sheet of PE. I use some dull edge of razor blade or old credit card to squeeze of excess epoxy, then cut the cloth to shape (measure the diameter of the mandrel both thin and thick end, multiply by pi and add a few mm extra). The carbon is to the precise dimension of the final tube, but glass cloth has some 6 to 10 mm extra. This will help to wrap the composite around the mandrel.

I have a slow-turning electric motor to rotate the mandrel (used to ask wife for help, but the motor makes me more independent!). I start my rotating the mandrel and applying a thin layer of epoxy. I then take away one PE sheet from the composite sandwich (leaving the other to support the packet), and apply one egde of the sandwich onto the mandrel. Working from one end to the other, I push the composite firmly onto the mandrel while lifting the remaining PE film (on top of the parcel) off the laminate. When the edge is lifted all along the tube, it is easy to use the PE sheet to wrap the composite around the mandrel and at the same remove the PE sheet. Finally the excess glass at the end of the laminate roll turns over the carbon-glass laminate, and can be smoothed over the end to make a laminate that packs tightly against the mandrel.

I next take some tape, maybe 15mm wide. This is purpose made, just plastic film, no glue. But ordinary packing tape could be used (and we used to use), with glue side out! Starting from the thin end, I attach the end of the tape to the mandrel outside the laminate, then using the electric turning motor to turn the mandrel, wrap the laminate with the tape, overlapping so that the next layer goes 2/3 or 3/4 over the old tape, and only 3 to 5 mm of the tape presses onto laminate each rotation. Wrapping this way all the laminate squeezes the laminate tightly against the mandrel and pushes all excess epoxy out. You can see how the epoxy makes pearls onto the tube at this stage. Finally I laminate a thicker lump to the thick end of the tube, wipe off excess epoxy from the tube, and let the laminate cure (overnight or so, some elevated temperature is good so I took it to the technical room of my house, where it is maybe 30 to 40C over the top of the central heating unit).

Once the epoxy is cured, I first remove the tape from the mandrel. I then insert the mold against a vise so that the lump at the thicker end rests against the jaws, but these do not clamp the mandrel itself. I tap the thin end lightly with a hammer. This sends the force/impact to the lump and from the lump to the root of the tube, forcing the laminate tube along the tapering towards the thin end of the mandrel. Several taps release the tube little by little (on thin P-30 tubes you can actually see how the "release" moves along the tube tap-by-tap), until the tube pops off. Then all that remains is to cut the tube to final length, and wax the mandrel for the next tube.

For E-36, the body tube is as described, 600mm long, 1 layer 100g/m2 carbon with some extra rowings for extra stiffness. And 50g/m2 glass for torsional stiffness. The wing tubes are 500mm long, one layer of the same carbon, no rowings as wing tubes do not need to be so stiff, but the glass is 100g/m2 for more torsional stiffness.
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Re: E-36 "Puzzle"
Re: E-36 "Puzzle"
Re: E-36 "Puzzle"
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Tapio Linkosalo
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« Reply #21 on: July 12, 2016, 08:20:36 AM »

But I also feel that the F1S/ E-36 class might benefit from some new ruling. Like German 2m RES where carbon are no do, except for tailbooms and spars .
I fear we soon buy our models from the east european suppliers... And that would kill this beginner friendly and booming class.

I do not see it likely that East European model makers would start producing E-36 models shortly. For one thing they seem to mainly focus on "large" FAI classes (F1ABC plus F1Q), even in F1H there are fewer manufacturers, and almost none for P-30. In E-36 the model layout and trims are very much dictated by the parts (motor and battery), so it would not be easy to provide "ready to fly" models unless you even provide all the electronics. I suspect E-36 will remain more like "tinkering" class like P-30 is, where you have the kits and short kits, but build the models yourself. Also I do not think the banning carbon would make so much difference, I think I could build "Puzzle" all wood, with balsa box fuselage, pine spars and lots of diagonals to make the wing stiff enough. Using carbon tubes is just easier and makes a model that is possibly more stable against warps.

But, I am afraid that sooner or later the rules will need to be touched. I first was impressed but the lateral thinking, aiming to limit the power with fixed layout instead of battery weight or electronics as in F1Q. But I see that the power of E-36 is going too far out, and that is something that will make the class less beginner friendly.
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Tapio Linkosalo
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« Reply #22 on: July 13, 2016, 03:03:32 AM »


Breakdown of the model weights is:
....
   + tailboom 4.5g

Correction: tailboom weight 6 grams (at almost 10 cm longer than the final length, but enough extra boom length to accommodate a rear fin if needed).

I just released a new boom from the mandrel, so was able to weight it separately.
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« Reply #23 on: July 13, 2016, 04:39:23 AM »

Well Tapio . I am very glad I asked the question about the weight of the fuselage . Your breakdown is very useful information . In my articles on power models in the SAM1066 New Clarion online magazine . I always give the breakdown of weight as folk told me that this type of information is very useful . It gives people an idea of what to aim for and what is possible , that is if people even build power models anymore . A dying if not dead class here in the UK.
I noticed that your work bench is as tidy as mine, just enough space to work on what ever project is under way .
I shall be seeing Peter tomorrow and no doubt there will be much discussion on the power train etc that you use , as this does seem to be lighter than that which I use . The weights of my models all built of balsa and mylar and tissue covered are very close to the frame weights of your model . I can not comment on any relative stiffness with your models, mine appear to be adequate . I believe as the class develops , and runs get shorter, weights could become more important to ensure best performance . This could be countered very easily to maintain the "sporty " element of this class by having a minimum weight requirement.
Once again thank you for your very informative write up of making the carbon tubes . john
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Tapio Linkosalo
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« Reply #24 on: July 13, 2016, 07:17:15 AM »

I noticed that your work bench is as tidy as mine, just enough space to work on what ever project is under way .

Yeah. It is about time for my annual workshop clean-up. After that there is more room to work on for a while, but as months go on, I will always be too busy to built and not have time to clean the shop, until things end up like you see in the pictures....

I shall be seeing Peter tomorrow and no doubt there will be much discussion on the power train etc that you use , as this does seem to be lighter than that which I use .

I got myself also one of those 2208 / 2600kV motors, but it is 10 grams heavier,and hence would move my CG too much forward. Well, maybe a pylon leaning more forward would help. But anyway, even the current motor makes the 300mAh battery fail from 8 seconds on, so a hotter motor would need also a bigger battery. So for the time being I think I'll settle with this power train.
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