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Author Topic: Ellipse 16in.  (Read 2896 times)
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Sailaway
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« Reply #50 on: July 21, 2020, 01:46:16 PM »

Tapio, this is terrific.
You are truly very innovative and great engineering.
Can you share more info asto how you made these timers or will you make it commercially?
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Tapio Linkosalo
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« Reply #51 on: July 22, 2020, 01:21:42 PM »

That is a complicated question.

In principle the timer is quite a straightforward piece of electronics. One micro-controller, two FET transistors as switches for the rubber band burner and the buzzer. A switch. However as for CLG the aim is also to make the device as small and light as possible, I use surface-mount components, which are a bit harder to solder. So some expertise is required for soldering the device. Therefore even if I published the design, maybe not too many modelers could solder one together.

When it comes to making them for sale, the question is the limited amount of my hobby time and the time required to put one unit together. Thus far I prefer to do my own projects, as making timers for sale would be out of my hobby time. Making such small timers takes quite a lot of tinkering, so I would not be able to produce too many in my limited hobby time.
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Sailaway
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« Reply #52 on: July 22, 2020, 04:43:02 PM »

Thanks Tapio. I understand.

Still, looks great. Are these rubber band burning timer?
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Tapio Linkosalo
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« Reply #53 on: July 23, 2020, 02:03:05 AM »

Still, looks great. Are these rubber band burning timer?

Yes, a band burner. As in the video in the link on msg #40 https://www.hippocketaeronautics.com/hpa_forum/index.php?topic=24385.msg261933#msg261933
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Tapio Linkosalo
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« Reply #54 on: July 23, 2020, 03:04:57 AM »

All set up and ready to go. Just waiting for the calm weather to do the trimming. The yellow one is the 16", the other two are 18".

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Re: Ellipse 16in.
Re: Ellipse 16in.
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che
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« Reply #55 on: July 23, 2020, 12:10:02 PM »

That floor looks interesting.............

CHE
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Tapio Linkosalo
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« Reply #56 on: July 23, 2020, 12:31:25 PM »

... next pic will show the ceiling!
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Tapio Linkosalo
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« Reply #57 on: August 01, 2020, 04:53:19 AM »

So I made hinged rudders to the planes...

I cut a groove on one side through the carbon skin and foam, leaving the other skin as hinge. The rudder will be slightly offset and the air stream will press it against the adjustment, so no spring is needed.
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Re: Ellipse 16in.
Re: Ellipse 16in.
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Tapio Linkosalo
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« Reply #58 on: August 01, 2020, 05:09:31 AM »

I eventually had the chance to trim the new models. Two (16in and the other 18") had an interesting trim, not pithcing up much but rolling 90 degrees out of the launch bank, which results in rather nice transition to glide. The third one kept banking and required lots of rudder to counter that. Seems like that one had the wing ever so slightly rotated (launch turn side tip aft) causing an aileron effect (due to dihedral) maintaining the bank. I'll try reset that next to see if wing alignment has such strong impact on launch trim...
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Tapio Linkosalo
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« Reply #59 on: August 06, 2020, 02:42:20 AM »


During the previous trimming session I had to add some ballast to the nose of the new gliders to stop them from stalling. To avoid this, the next evolution version of the wing saddle. I replaces the two holes with M2 thread that accept the bolts attaching the wing to the wing saddle with oval holes, and add some square "nuts" underneath to lock the bolts onto. This way I can loosen the bolts, slide the wing forward or aft and re-tighten, to fine-tune the CoG location of the model. Without adding any ballast. The third hole in the saddle is for the decalage adjustment screw that will stay in the same position.

The same idea of adjusting the glide trim by sliding the wing is in use in my "Puzzle" E-36 model.
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Re: Ellipse 16in.
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OZPAF
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« Reply #60 on: August 06, 2020, 09:15:26 PM »

That 3d printer is being well used Tapio Smiley Neat.

John
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Tapio Linkosalo
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« Reply #61 on: September 16, 2020, 03:06:51 AM »

I went trimming my cats again yesterday. The 16-incher works like charm, but the 18-inchers give me grey hair. One of them seems pretty close to good launch, but tends to glide straight, despite considerable amount of tail tilt. If forced to open glide turn with rudder, it still tends to stall the _outboard_ tip slightly, further opening the glide turn. Also enough rudder to make glide turn results in a barrel roll (out of the launch turn direction and into the glide turn) on launch.

I wonder if this is an issue with wing warps? Maybe I should take out the wingtip inboard on launch, outboard on glide and re-glue it again with slight washout? I have build the wing with celluloid glue, so taking the panels out is possible with acetone.

I do not think it is an issue of tailplane warps. My tails are of carbon/foam construction, and they should not warp due to moisture....

« Last Edit: September 16, 2020, 04:34:36 AM by Tapio Linkosalo » Logged
Mike Thomas
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« Reply #62 on: September 16, 2020, 06:40:00 AM »

Could it be a wing balance issue? A bit of weight on the port wing tip may help.
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Tapio Linkosalo
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« Reply #63 on: September 16, 2020, 06:56:56 AM »

Could it be a wing balance issue? A bit of weight on the port wing tip may help.

Good point, I'll have to check (and test) that. Will add the weight onto the starboard wing though, as I fly my CLG models left-right pattern!  Grin
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Mike Thomas
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« Reply #64 on: September 16, 2020, 07:37:44 AM »

Will add the weight onto the starboard wing though, as I fly my CLG models left-right pattern!  Grin
[/quote]

Of course, I should have remembered that they fly clockwise in the Northern Hemisphere. Cheesy
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« Reply #65 on: September 16, 2020, 09:01:32 PM »

It may also be possible that the wing is skewed very slightly on the fuselage giving too much wash in on the inside glide turn wing panel. I have had this happen and nothing but a complete removal and replacement of the wing would solve the problem.

If this the case - it should show up in the climb as a  reluctance to transition to the glide.

John
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Tmat
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« Reply #66 on: September 16, 2020, 10:01:38 PM »

Possible wing skew, warps or differential weight. Is there a wash-in tab on the right center panel for the glide?

Tmat
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F1B guy...
But don't hold that against me!
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« Reply #67 on: September 16, 2020, 10:15:20 PM »

It may also be possible that the wing is skewed very slightly on the fuselage giving too much wash in on the inside glide turn wing panel. I have had this happen and nothing but a complete removal and replacement of the wing would solve the problem.

If this the case - it should show up in the climb as a  reluctance to transition to the glide.

John

I had a similar issue ... I made a mistake in construction and one of the wings had a bit of extra material (in a wedge shape) that resulted in a fatal left-hand spiral dive. Complete removal, disassembly, and inspection identified the problem. I won't make that mistake again. I paid extra attention to the possibility of skew when I re-mounted it to the fuselage stick.

-Dave
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Tapio Linkosalo
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« Reply #68 on: September 18, 2020, 01:37:49 AM »


I did not measure the lateral balance, but the wood from which I routed the wing seemed quite uniform, so I suppose the wings weight about the same. My wing is attached to the saddle with two bolts, so adjusting the skew is easy, just sand the attachment bolt holes slightly oval and tighten the wing to a new position. However, visually checking the wing does not seem to be skewed. Looking at possible warps, I noticed that the starboard wing tip (outer on launch, inner on glide) was attached with ever so slight washout to the center panel. Maybe this is the cause? I removed the port wing tip and re-attached it with slight wash-out, too. Now the weather would just co-operate could I go to the field and test. Seems however to go solidly until next week before the winds calm down a bit...
 
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« Reply #69 on: September 18, 2020, 02:12:51 PM »

it would be interesting to establish contests with this new design parameter... Smiley Smiley
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Tapio Linkosalo
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« Reply #70 on: September 24, 2020, 08:12:16 AM »

Yesterday was first chance to test the model with re-glued wing tip. There was indeed improvement! Unfortunately I did not manage to sort the model totally out, as after a couple of launches I realized that the finger-hold is missing, cracked clean off at fuselage bottom. The nose part is printed flat/inverted, and 3D prints are weakest along the layers, so that is an obvious weak spot in the nose pod. However, the 16" model has had way more launches and still seems to be solid, so it may have been just an error in the printing. Too little plastic feed (the filaments tend to vary) or too low temperature. I'll try another nose, and if the problem persists, then re-design the nose with a carbon rod insert to support the finger hold.

As far as I got, the launch pattern was pretty close to good. A little bit too little roll, so the model tended to stop inverted, not banked to slip into glide. The glide turn also was not too strong, but rather wide open, so I need to add some more rudder for glide and then see how it impacts the climb pattern.

Changing the nose will be an interesting experiment also. The tailboom is glued on, but has an clear groove on the nose to sit into, so that should go in the same place and position. Wing is with one bolt only, and the key for wind incidence adjustment part is glued to the boom. So I'd expect the model should retain trims after the pod change. We will see!  Cheesy
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Tapio Linkosalo
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« Reply #71 on: September 25, 2020, 02:39:25 AM »


Well well, seems like it was a matter of under-extrusion. I had set my printer for 1.75mm filament thickness, and the yellow filament, that I have used in the 16" glider, that has a large number of launches and where the finger tab holds just well, measures 1.78mm. The pink, from which the broken tab was printed, measures 1.72mm. Mind you, the printer measures the filament amount by length, so the filament diameter is a critical measure for the mass of the material. I re-adjusted my printer for filament thickness of 1.70mm (seems to like a slight over-extrusion) and increased the print temperature from 200 to 210C (should also produce stronger prints), and now a newly printed pod seems stronger. We will see! Cheesy
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