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Author Topic: What Did You Do Airplane Wise Today?  (Read 101829 times)
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OZPAF
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« Reply #1300 on: February 16, 2019, 05:22:48 PM »

Sounds good Jim. Smiley

John
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p40qmilj
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« Reply #1301 on: February 17, 2019, 11:44:08 AM »

 Grin watched AIR STRIKE its a direct tio video movie made in china.  covers late 30's air war in china lots of cgi  I 16s, nells, zeroes and claudes. a single p40 makes a gust appearance at the end.  corny but air action scenes are fun and reasonably realistic.\

jim Grin Grin Grin Grin Grin Grin Grin
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MKelly
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« Reply #1302 on: February 18, 2019, 08:49:42 PM »

Spent some quality time on the Wicko.  It's starting to look like an airplane!

Mike
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« Reply #1303 on: February 19, 2019, 01:03:17 AM »

Wow!  Lovely job on the Wicko, Mike!

Scot Dobberfuhl
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dputt7
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« Reply #1304 on: February 19, 2019, 04:32:41 AM »

Spent some quality time on the Wicko.  It's starting to look like an airplane!

Mike

   I don't think I will ever build another model  Cool
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Pete Fardell
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« Reply #1305 on: February 19, 2019, 05:28:25 AM »

Wonderful work! I’ve no idea how you build and finish a model so neatly.
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OZPAF
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« Reply #1306 on: February 19, 2019, 07:57:40 PM »

Another fine effort Mike - hard to fault anywhere. Discouraging for normal modellers Smiley The canopy framing looks very sharp(so does the Wicko emblem). Separate sections in between the frames on the side?

John
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DerekMc
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« Reply #1307 on: February 20, 2019, 03:41:31 AM »

I spent most of the last two days driving home from Lost Hills. A picture I took while waiting for the Max Men F1B flyoff:

https://i.imgur.com/8xxX83W.jpg
What Did You Do Airplane Wise Today?
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They fly better when you smile!
Derek
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« Reply #1308 on: February 20, 2019, 04:05:52 AM »

A very good photo Derek - from all points of view.  Would it be possible for you to let me have a better quality image purely for my private "collection" please?

I could seriously consider sending a snatch team to capture Mr Kelly and "persuade" him to divulge his secret ability to cover and finish models to such a high standard to us lesser mortals. But then I reflect on the fact that had i done so similarly with a great artist of say a concert pianist whilst they might happily tell me how, it would ultimately lie in my ability to employ such knowledge.  So a bodger I must remain!   
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OZPAF
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« Reply #1309 on: February 20, 2019, 05:00:43 AM »

Outstanding photo Derek.

John
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MKelly
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« Reply #1310 on: February 20, 2019, 10:54:24 AM »

Fantastic photo Derek - love the double rainbow with color-matching airplanes on the grass.

I could seriously consider sending a snatch team to capture Mr Kelly and "persuade" him to divulge his secret ability to cover and finish models

Thanks for all the compliments on the Wicko, but you're being much too kind.  The front end came out pretty clean, but there are wrinkles on the stab, marks on the LE from teasing out wrinkles there, and the tops of the wheel pants show some incipient varicose veins where I tried to stretch the tissue too far.  The sharp edges and graphics of the printed tissue draw your eyes away from the flaws...

John, the side windows were done by tacking a single piece of clear giftwrap across both windows on each side of the fuselage before covering.  I printed the tissue for the fuselage sides, cut out the window openings, then applied the tissue over the glazing and sealed the edges down with thinned canopy glue.  The side tissue is a single piece from the aft end of the cowl to the back - easy because the sides are flat.  There were a few wrinkles on the diagonal at the bottom of the rear windows, but between a water/alcohol mist and some nitrate they're just about gone.

Mike
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DerekMc
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« Reply #1311 on: February 20, 2019, 01:44:51 PM »



A very good photo Derek - from all points of view.  Would it be possible for you to let me have a better quality image purely for my private "collection" please?


Sure. How big of a file can you handle? The original is 13mb. It's a panorama picture.

Thanks for the compliments on the photo. Incredible sight on the field. And thankful that big cloud was over there and not straight up!
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Derek
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« Reply #1312 on: February 20, 2019, 02:09:28 PM »

Spectacular photo Derek - quite remarkable.

I'm rushing up a model to test my new 0820 coreless electric motors that arrived from China yesterday. My interest is in using these little motors for ducted fans but I think I'd better take some baby steps first. The supplied props are much better than I'd expected - and much bigger. Specs on various websites state "max prop size 65mm" for the 0820 motor. It turns out that they're referring to radius. These motors came with > 65mm radius props. . .5 1/2" diameter in fact. The vendor also bundled in a neat gearing system, about 5 to 1 reduction. It looks to me as if the energy lost in the gears might well be in the same order as the efficiency gain of a bigger slower prop. Lots of playing round to be done. I'm lucky in possessing a laser rpm meter so I shall be making lots of measurements. I jammed a motor into one end of a plank of balsa and ran the  motor on 1 1/2 volts. Finding the point along the plank where the motor could hover gave me a very crude idea of static thrust. It seemed to be about 6 grams. I think it should fly the 16" span model I'm nailing together, given that the capacitor will deliver 2.7 volts initially. Holding the plank as it 'hovered' also alerted me to what seems like very high torque, and fierce (relatively speaking) gyroscopic forces from attitude changes. I hope this won't be problematic.

The pic shows a motor with prop and a 10 Farad capacitor with the plastic sheathing stripped off to save ≈ 0.1g weight. BTW the seller on Amazon wasn't lying about the weight of these motors: 4.9g each including wires. The 'supercap' weighs 3g in the nude with its wires clipped short.

Stephen.
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OZPAF
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« Reply #1313 on: February 20, 2019, 11:52:47 PM »

Thanks for that Mike. Using such thin plastic would be a large part of the neat appearance - no lumps.

Stephen - I think from what I have seen that you could expect a lot more than 6gms thrust with that motor/capacitor/prop combination.

My friend's effort in India indicates an initial thrust of around 16 gms on a 10F suopercap with a 65mm dia(not radius) prop. This quickly drops though but from analysing the flight video I would estimate that it ran at around 10g for another 10 secs or so.

Interesting idea as they are very high reving - you would have a good chance of making an edf work.

John
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« Reply #1314 on: February 21, 2019, 02:50:35 AM »

Aha, thanks for the info John. The ≈ 6g thrust was on 1.5 volts only. I have no idea about electronics so I don't know how linear the curve of volts against revs would be. The high revving is indeed why I thought of EDF suitability, but as yet the whole area is a mystery to me - quoted unloaded  rpms are 40,000 or more for this motor, and yet it happily spins a 140mm prop at 'real world' rates. I believe (perhaps wrongly) that obtaining best efficiency from electric motors is a matter of not overloading them, i.e. having them spin fast, but I don't even want a caged fan spinning at 30,000 rpm Shocked. Anyway I have a battery for my rpm meter arriving today along with batteries to charge the capacitor so I should start finding things out soon.

Stephen.
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« Reply #1315 on: February 21, 2019, 05:00:38 AM »

Hi Stephen, are you using the gearbox? If not that's an enormous prop for direct drive  Shocked

The 8.5mm coreless motors (depending on quality) will give you 35-42g of thrust on a 65mm King Kong direct drive prop revving at something like 25,000-32,000 rpm on 1 cell ie about 4 volts. This sounds fast but is perfectly normal for electric and exactly where they are most efficient at approx 75% of the no load speed.

Would you be able to share your motor source? I've tried the Banggood geared ones similar to the Voodoo style but they aren't great on thrust (the prop is rubbish.) Fine for a fun model though.

6 grams of thrust really does sound low for an 8.5mm even at 1.5V  Undecided a 6mm motor should easily do 10-12g on 1S these days. This would be with a 32mm prop so could be used in a ducted set up.


Jon
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« Reply #1316 on: February 21, 2019, 11:04:35 AM »

Hullo Jon, I looked on Amazon and can't re-find the exact line I ordered - that's the problem with generic stuff from China. I can tell you that the vendor was/is called Ascot City and the name 'Sourcingmap' came into it. The offer was 2x CCW 0820 motors with the extras mentioned above. Less than a fiver each inc delivery IIRC. I bought two pairs, knowing that it was a bit of a punt. The supplied props are handed to spin directly - gearing them would have them spinning backwards. This added to my confusion as to what I was dealing with - I was expecting tiny propellers and to chuck 'em straight in the bin. I couldn't really believe that even tiny props could spin at 10s of thousands rpm. Perhaps the motor simply can't perform with such big props. I just tested the static rpm: 6,500. I may cut down one of these props but it seems a shame since they're actually quite nice and might be useful some day somewhere.

Stephen.
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« Reply #1317 on: February 21, 2019, 12:16:45 PM »

0820 motors with the extras mentioned above. Less than a fiver each inc delivery IIRC.

I bought 5 of these with gearbox and the same size prop.  Using the gearbox the 5.25" prop just did not work with a 1S lipo (nom 3.8v).
The models weighing between 20 - 30g would just about maintain height from a hand launch.  I cut the props down to 4" and 4.25" dia and they climbed well and would maintain height on half throttle (radio controlled of course).  I have made a FF model with same motor and battery but haven't wrung it out yet.  Don't forget to oil the bearings on the gearbox.  Be careful when assembling the bits and pieces - it is easy to push the shaft through the rear plastic cover.  Support the wires with UHU Por or similar - the wires can fall off very easily.  Other than that they work well.  I understand from a clubmate that for direct drive there are small drone motors that can be used in this way.  Regarding ducted fans - there is a keen group flying these (radio controlled) in the St.Helens area.  The prime mover makes and sells very light 3D printed duct/motor mounts complete with motors and small commercial 3 blade props. 

Ralph
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« Reply #1318 on: February 21, 2019, 02:09:38 PM »

"She flies, Orv!"

"I told ya she would, Wilb."

Well, after a fashion anyway. This is with the plastic prop driven directly. It's windy today but too lovely and Spring-like a day to waste so I had to give the model a chuck even tho' it's not finished. With a couple of AA batteries in a pocket and the charging lead sticking out, fuelling up these things is a doddle. I was charging for 6, then 10 seconds per launch. The wind made trimming decisions difficult. After a few flights it decided to do the right thing and fly into a tree after about fourteen seconds of circling. Getting it down was a pain, involving a stepladder and loppers. I made the model strong though, to imitate the weight of scale models. I look forward to experimenting with different props - maybe the key to this business. I guess the question is what's the duration going to be like?

Pictures, 1) checking the no-load rpm. The motor runs a long time under no load, this is well through the run but even at the start I think it was reading less than 30,000. The motor is rated for 3.7v so 2.7 is tame, but perhaps lets the motor last longer. The battery box is visible behind the stbd wing and the end of the improvised charging lead pokes into the picture centre-left.

3) and 4) The model is nose-heavy so I fixed the capacitor against a cabin bulkhead. There is a slot below the pins through which to insert the charging lead. The improvised circuit breaker is probably mis-named: the balsa case indicated contains two brass strips sprung against each other - pushing a strip of thin plastic into the slot (right-hand pic 4) separates the brass and breaks the circuit. Probably the plastic strip is the circuit-breaker. The tangle of wires can be tamed when I have a clue what the best final arrangement might be.

The model needs a windscreen and chin cowling and landing gear to finish, but adding up the various sessions I reckon it took less than two days to get to this stage. Weight as seen 20.2g; wingloading 0.084g/cm2 [0.54g/sq in]. A 30 second charge gives a static run over a minute with the prop fitted but I would guess only 40sec of this - perhaps less - is powerful enough to keep the model aloft.

Thanks for the info Ralph. I was confused but I'm even confuseder now. The motor leads on these motors look secure - they're supported by a plastic plug and I gave them a waggle on first inspection. These are drone motors, according to the comments on Amazon.

Stephen.
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OZPAF
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« Reply #1319 on: February 21, 2019, 08:09:27 PM »

You are on the way Stephen!. Wilbur is right Smiley
Check out Utube site sonex413 if you haven't already - a mine of information there.
As a comparison my friend in India is flying a 20g model on a 720(7dia) motor on a 10F capacitor with a direct drive 65dia prop. He has only charged it to around 3.0v.
Not sure of it's thrust output but by rough estimates from the climb angle on the video it is close to 16g at launch dropping quickly to stabilise near 10g for around another 15 - 20secs? Average flight times are 30-40 secs with a longest flight of 1minute(no doubt with a bit of thermal; assistance).

Location is a little different to yours Stephen Smiley

https://youtu.be/2nIcKaoqUmM

John

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« Reply #1320 on: February 22, 2019, 03:23:02 AM »

That does look very much like the banggood one: https://m.banggood.com/Coreless-Reducer-CW-Motor-Propeller-Combo-Set-For-RC-Models-DIY-p-998786.html

I bought it to use the gearbox as a motor mount but did a quick thrust test. I got around 15g on one cell - not great at all. The motor wires were the same, I needed to swap positive and negative to get the correct rotation.  I will test the BG motor on DD too at some point.

Without the gear box it will be massively overpropped and to be honest I'm surprised you're getting any thrust at all  Cheesy if you PM me your address Stephen, I will pop a couple of 65mm props in the post to you (I have loads spare for E20) you should get a lot more thrust with them.

As John suggests by getting the efficiency right a much lighter set up is possible with a 6 or 7mm motor.

Jon
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« Reply #1321 on: February 22, 2019, 01:27:37 PM »

Jon, that's a very kind offer, and I might take you up on it down the line - but for now I'm keen to see what can be done with balsa props (see below). Yes, the motor you link to could be the identical item - that's why I call 'em 'generic' - but it looks as if the wires may enter at a different spacing on the backplate. I bet there are whole factories in China churning out these babies. When looking into these motors I read the drone enthusiasts writing that if you run them backwards they don't last long - I'd have thought they'd be entirely symmetrical and would run as well one way as t'other. The 'droners' also say they should be run-in by running at 1.5v only for some initial period. When one breaks I look forward to breaking into it to see what's what.  Do you think a 6 or 7mm motor could fly a chubby model like this with 0.56g/sq in wingloading? I think I may have underestimated the potential of these little things.

John, thanks for the link. I seem to recall from a different thread that you're the instigator or designer of the model in the video. It's a charmer.

Thismorning I made a card windscreen and a balsa lower cowling and reworked a couple of 'pre-owned' prop blades and an old hub into a prop, all for my supercap test model. I haven't measured the prop pitch but it's not quite as fine as the black plastic prop that came with the motor. I guess the area is about the same but the diameter's less: an arbitrary 116mm (just over 4 1/2"). The prop weighs 0.6g against 1.1g for the plastic. Model weight up to 21 grams, 0.088g/cm2 [0.56g/sq in].

After the fog lifted I managed to fly the model into several trees at lunchtime and was getting tetchy, but the wind died later and I got some better flights. This flight has 15 seconds of charge (sonex413 says 30 sec = a full charge and he's got the necessary meters to measure it so that's good by me). It's a bit stally because I'd moved the port aileron down a touch to open up the turn. If there's a flat calm I might try a full charge but I'm tired of it hitting trees. . .yesterday stepladder and loppers; today ladder, bowsaw, loppers and hook. I notice the battery voltage of the two AAs I'm using for charging is down to 2.8v so they're holding out well given the number of charges they've already provided.

Stephen.
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« Reply #1322 on: February 22, 2019, 02:34:44 PM »

Stephen, The brushes in these motors are very fine wires, to reduce friction and they are arranged to be "trailing". If they are run the wrong way then the free end of the wire can easily catch and that is the end!!!
Ron
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« Reply #1323 on: February 22, 2019, 03:36:31 PM »

Thanks for the gen, Ron - d'you have any insight to the 'running-in' idea?

Cheers,
Stephen.
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« Reply #1324 on: February 22, 2019, 04:00:41 PM »

Stephen, the running-in helps to obtain a better fit between the brush and the collector. Using the brushed motors as we modellers do, with higher currents than what the motors are designed for, the contact area between brush and collector has to be as big as possible to transmit the current without generating to much heat. The run-in is done leaving the motor running for some time without load and at lower tension than the designed one. You could use one (1) NiMh cell for the run-in.

Urs
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