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Yak 52
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« Reply #825 on: August 31, 2019, 03:18:24 PM »

Thanks John  Cool

Good news Ricky! The Flying Aces was winnndy but there were enough lulls and some decent air for me to get the new model (sort of) trimmed with an old wing. Pleased with the dead stop timer and the prop brake works in flight. A really lovely day in spite of the blustery conditions and nice to catch up with people as well as meet some new faces.

I've attached a picture of Andy Sephton's prototype build of Kevin Wallace's SAMS E20 design. It has options for both the original Ferry 500 motor and gear (heavy but powerful) and also using the SAMS Electroflite geared 8mm motor. Both were flying really nicely and I think the kit would be competitive under the US rules with a Parkzone DD motor.

SAMS are also now selling Ferry 500 timers for the Aeromodeller plan/PMFC competition as well as a lightweight FET version I've made them for Open models.
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Yak 52
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« Reply #826 on: September 29, 2019, 04:49:59 AM »

I've attached a picture of Andy Sephton's prototype build of Kevin Wallace's SAMS E20 design. It has options for both the original Ferry 500 motor and gear (heavy but powerful) and also using the SAMS Electroflite geared 8mm motor. Both were flying really nicely and I think the kit would be competitive under the US rules with a Parkzone DD motor.

SAMS are also now selling Ferry 500 timers for the Aeromodeller plan/PMFC competition as well as a lightweight FET version I've made them for Open models.

Ferry 500 Timers are now available to buy from SAMS:
http://www.samsmodels.com/ferry-500-fet-timer

As is the E20 Kit: http://www.samsmodels.com/sams-e20
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DHnut
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« Reply #827 on: October 27, 2019, 05:19:21 AM »

Jon,
       I am well into a SAM E20 and starting to cover. The questions I have are, is there a preferred mounting for the timer and battery? I have a viscous timer that I am looking for a home for, any suggestions. The kit flew together with no problems and looks fine for our small field providing I have a DT. Also what is the normal prop used?
I have almost completed 3 Hangar Rats as well as part of the replacement of one lost at our recent Morrinsville meeting. Stuck behind a basketball score board. This gives abreak from scale modelling.
Ricky
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Yak 52
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« Reply #828 on: October 27, 2019, 06:12:39 AM »

Hi Ricky,

Did you go for the SAMS geared motor set up or the Ferry 500 direct drive can version?
The geared motor uses a GWS 5x3 and soft rubber hub mount (fairly easy to source but Kevin also sells them) but the direct drive CN12 or N60 can motors take a GWS style 3x2 prop (becoming a little harder to find.)

The timer can be mounted on a blob of hot glue. The batteries can be velcroed, taped or wired on but it helps to have a suitable cut out in the pylon. On my Ferry 500 with a 2S 180mah this is tight enough for a push fit - no further securing required.

Jon
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DHnut
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« Reply #829 on: October 27, 2019, 03:31:13 PM »

Jon,
      I have the geared SAM motor and I have a bunch of the props so that one is solved. The timer mount is clearly not complex and I will find a home for it. I need to get batteries. I will also have another read of your Ferry 500 article in aeromodeller.
Just need to lighten one of the imers for a DT.
   Ricky
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Yak 52
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« Reply #830 on: October 28, 2019, 04:55:31 AM »

Ricky, for the viscous dampers I cut off the lugs and roughen the back with sandpaper before CAing them on the pylon.

For the geared coreless motors you need 1S lipo of around 160mAh (although 200mah can actually give better power to weight ratio.)

Jon
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DHnut
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« Reply #831 on: October 28, 2019, 06:10:34 AM »

Jon,
      Thanks for the info. I think I have a 1S cell on the required capacity and the timer is ready to modify. The wings and tail are covered and I will work on the fuselage tomorrow.I have been playing witha neighbours 1931 Austin Seven today. Never though I would drive one of those again. As an apprentice I ran one for 3 years and it taught me a lot.
Ricky
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Tapio Linkosalo
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« Reply #832 on: January 24, 2020, 06:16:04 AM »

How much current does the E-20 motor draw? Just wondering, what size of FET would be needed in the timer to control the motor?


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Yak 52
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« Reply #833 on: January 24, 2020, 11:36:18 AM »

How much current does the E-20 motor draw? Just wondering, what size of FET would be needed in the timer to control the motor?

Hi Tapio,

Well... it very much depends on the motor Smiley and the rules you fly E20 to...

Ferry 500's (in the UK) use a CN12 drawing about 1.7A on the standard 2s Lipo and 3x2 prop.

Open E20's where I use 1S and a 8.5mm or 10mm Coreless would be 2-3A but some 'hot wound' ones can draw 5A.

Some of the Open E20 brushless motors I've tested are around 5-6A but obviously they require an ESC.

The Parkzone 8.5mm motor specified for the American competition is not too hot so probably under 2A. I think they are looking for an alternative motor now as the official one is hard to find, but I've not heard anything for a while.

Are you planning a Peterborough style FET timer or something more sophisticated? We use a 12A FET in the standard PMFC but I use a 6A in a smaller version. It's not just about the amp rating though - the 'power dissipation' is a factor ie how much heat it produces and can lose through the case (particularly as it shuts the motor down.)

Jon
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Tapio Linkosalo
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« Reply #834 on: January 25, 2020, 01:15:13 AM »


We are just about to start flying E-20 here in Finland, so no established rules. And the diversity of rules around the world makes it harder to settle to some set. I think I would be leaning towards (max) 8520 -sized motors (no specific brand named as any type seems to become obsolete in the long run), I just wonder if we should define the max allowed kV value too.

I have been making my own timers for other classes, based on a micro-controller, so I was planning of following that route. I have been using small (sot-23) FETs to switch features on and off, and I was wondering if they could manage the DC motor switching too, but most likely not. So a bigger FET would be needed. I have been wondering also if the timer should incorporate a brake, and how that should be wired - can I use a single IO pin of the microcontroller to turn off motor and turn on brake fet, or should I have a short delay between the functions (to avoid short circuit) and thus use two pins.There are some H-bridge chips that would have both run and brake functions driven from a single IO pin, but they are rated to 1 to 1.5 amps max.

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Yak 52
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« Reply #835 on: January 25, 2020, 05:22:20 AM »

We are just about to start flying E-20 here in Finland, so no established rules. And the diversity of rules around the world makes it harder to settle to some set. I think I would be leaning towards (max) 8520 -sized motors (no specific brand named as any type seems to become obsolete in the long run), I just wonder if we should define the max allowed kV value too.

Yes, when we started flying E20 here in the PMFC we were influenced by windy conditions and our small field. So the Ferry 500 rules favoured heavier/robust/simple models on a short motor run. Motor obsolescence was then the motive to try an 'anything goes' Open rule. The hope was that the freedom to innovate would allow the class to evolve and improve. The sample size is small  Cool with only a few participants and it's an ongoing process. My own developments are pointing towards using a 10mm coreless on 1S. The 8.5mm motors are more available and you can get some good ones but the 10mm's have that bit extra thrust/weight which is important for our short motor run time.

We also didn't want to get too technical with the rules by limiting power like F1Q  Shocked

I have been making my own timers for other classes, based on a micro-controller, so I was planning of following that route. I have been using small (sot-23) FETs to switch features on and off, and I was wondering if they could manage the DC motor switching too, but most likely not. So a bigger FET would be needed. I have been wondering also if the timer should incorporate a brake, and how that should be wired - can I use a single IO pin of the microcontroller to turn off motor and turn on brake fet, or should I have a short delay between the functions (to avoid short circuit) and thus use two pins.There are some H-bridge chips that would have both run and brake functions driven from a single IO pin, but they are rated to 1 to 1.5 amps max.

SOT 23 should be fine - I have used some that are rated for 5 or 6A. (On a short run though) I generally use TO252 or SOT223 for the simple Peterborough timer as they are easier to solder and the design doesn't use a circuit board.

I have a more sophisticated analog circuit that has a fast cut off and prop brake - a brake will be needed for coreless motors because they freewheel easily and spoil the glide.

I'd be interested to see what you come up with Tapio, I have been working towards an etched PCB design incorporating a DT but have stalled a little with indoor projects taking precedence. It would be good to collaborate Smiley


Jon
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DHnut
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« Reply #836 on: January 25, 2020, 06:58:02 AM »

Hi Jon,
          I was interested in your comment about not allowing the prop to freewheel. Is this because it is small and the cone of disturbed air is small?
I am in the UK at the moment and plan to be at Bushfield on the 8 February, just spectating and taking photos as well as catching up with you all.
Also I am looking at taking batteries home as cabin luggage for the E20's, that will solve that supply issue. Your rules look very practical and have the benefit of having been in use for a while. We will pick them up for our small field events and see if there is any need to change that I see as unlikely. One Ferry 500 has already vanished upwards so the glide is not to shabby.
Ricky
   
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Tapio Linkosalo
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« Reply #837 on: January 25, 2020, 07:30:46 AM »

I was interested in your comment about not allowing the prop to freewheel. Is this because it is small and the cone of disturbed air is small?

With low pitch (or actually P/D ratio) the freewheeling prop brakes more thana stopped one. The prop blade airfoil is actually lifting, but backwads. Thus it would be beneficial to stop the ptop. For high P/D and wide blades (as in rubber props) things are different, freewheeling is better.
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Tapio Linkosalo
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« Reply #838 on: January 25, 2020, 07:34:34 AM »

Yes, when we started flying E20 here in the PMFC we were influenced by windy conditions and our small field. So the Ferry 500 rules favoured heavier/robust/simple models on a short motor run. Motor obsolescence was then the motive to try an 'anything goes' Open rule. The hope was that the freedom to innovate would allow the class to evolve and improve. The sample size is small  Cool with only a few participants and it's an ongoing process. My own developments are pointing towards using a 10mm coreless on 1S. The 8.5mm motors are more available and you can get some good ones but the 10mm's have that bit extra thrust/weight which is important for our short motor run time.

We also didn't want to get too technical with the rules by limiting power like F1Q  Shocked

But I think E-36 also shows a warning sign how performance goes way too high, if the power is not sufficiently limited.

For the moment I think that defining motor dimensions (8520 max), kV (50000 max) and prop max diameter, together with battery max voltage (4.2V to avoid HV lipos) and maybe max capacity might be a sufficient and easily checked means to be the power restricted. I think that would be the rules set that I will be suggesting for our local rules in Finland.
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Tapio Linkosalo
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« Reply #839 on: January 25, 2020, 07:44:20 AM »

SOT 23 should be fine - I have used some that are rated for 5 or 6A. (On a short run though) I generally use TO252 or SOT223 for the simple Peterborough timer as they are easier to solder and the design doesn't use a circuit board.

I have a more sophisticated analog circuit that has a fast cut off and prop brake - a brake will be needed for coreless motors because they freewheel easily and spoil the glide.

I'd be interested to see what you come up with Tapio, I have been working towards an etched PCB design incorporating a DT but have stalled a little with indoor projects taking precedence. It would be good to collaborate Smiley

I attached a picture of my E-36 timer. It uses a 8-legged soic-case PIC for microcontroller, drives the ESC and one servo, has input for RDT (actually coupled with the switch so you can stop the motor and program by the start button too), and uses a small buzzer to notify the set flight time, model armed status, and is used a locating beeper once the model has landed. Something similar, maybe even a tad smaller should work for E20, and use an onboard FET for driving the motor (and another FET for brake). My timer uses a Palm handheld for setting the times, as I use that also for my bigger (glider, wakefield, and F1Q to come) timers. Not very handy if you do not have one already, but for me it uses the same sofware on Palm for all the timers. Yes I have plans to migrate the software to Android, once I have the extra time... Smiley

The buzzer is really useful for small models to locate it after landing!
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« Reply #840 on: January 25, 2020, 08:00:16 AM »

How about using the E36 timer interfaced to a driver / brake pcb added to the rear of the coreless motor or as an in-line device in the motor lead. I would recommend adding a time delay so both FETs are not on together or at least some small value resistive component in the brake FET circuit.

A little more weight perhaps but this 2 part concept may have other merits or convenience to you.
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Tapio Linkosalo
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« Reply #841 on: January 25, 2020, 08:34:39 AM »

How about using the E36 timer interfaced to a driver / brake pcb added to the rear of the coreless motor or as an in-line device in the motor lead. I would recommend adding a time delay so both FETs are not on together or at least some small value resistive component in the brake FET circuit.

A little more weight perhaps but this 2 part concept may have other merits or convenience to you.

Definitely a plan to start with. If the setup works OK and there is an urge to go even smaller footprint, then maybe design a PCB just for the E20.

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Yak 52
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« Reply #842 on: January 25, 2020, 09:29:57 AM »

But I think E-36 also shows a warning sign how performance goes way too high, if the power is not sufficiently limited.

Yes, I agree. It's not hard to achieve excessive power. I have a build going which uses a Racerstar BR1104 on 2S that in theory will give me 95g static thrust for a 50g (ish) model. The question is will it be possible to trim  Roll Eyes The idea in the Open class is that any excesses will weed themselves out - build too powerful or too light and it will bite you. One of our members used an AP03 (I think) but found he couldn't trim it without restricting the power. Surprisingly after a summer of Open flying the Ferry 500 class models are still very competitive in the Open class even though they are somewhat 'agriculural' Smiley but it's still early days.

kV (50000 max)

Do you mean 50000 RPM max? Usually 8.5mm coreless are around 17,000-19,000 Kv at best. I've tested some of these (Micro Motor Warehouse CL-0820-18 Dark Edition) and you only get a gram or two more static thrust for considerable extra amp draw. This means greater demands on the battery capacity and C-rating so I'm not sure they make much improvement on balance. I think a minimum weight limit as per the American rules is probably effective too.


Look forward to seeing you Ricky Smiley
As Tapio said - with a low pitch, small blade area prop such as found on electric models it's less drag to stop it windmilling. The brushed 12mm motors for Ferry 500 have enough resistance to stop naturally so no brake is required. The coreless ones freewheel much more easily.

My head is in scale mode at the moment but I will be preparing for the summer flying E20 soon.
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DHnut
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« Reply #843 on: January 25, 2020, 09:31:39 AM »

Thanks for the explanation Tapio. I am trying to promote small field classes because inspite of being a small population flying sites are difficult to find within a reasonable distance of urban areas. At least we do not have to deal with a river and lakes being nearby. Also it provides an entry level into electric.
Ricky
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Tapio Linkosalo
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« Reply #844 on: January 26, 2020, 02:52:46 AM »

kV (50000 max)

Do you mean 50000 RPM max? Usually 8.5mm coreless are around 17,000-19,000 Kv at best. I've tested some of these (Micro Motor Warehouse CL-0820-18 Dark Edition) and you only get a gram or two more static thrust for considerable extra amp draw. This means greater demands on the battery capacity and C-rating so I'm not sure they make much improvement on balance. I think a minimum weight limit as per the American rules is probably effective too.


Yep, the advertisers caught me here. Seeing a figure I thought it was kV, but it is indeed rpm.

 
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Tapio Linkosalo
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« Reply #845 on: January 27, 2020, 11:26:15 PM »


Some thoughts on the E-20 timer. First, there are IC:s intended for motor control that could provide both switching the motor on and off, AND a short-circuit brake to stop the prop from spinning, and both controlled by 1 pin. Such as TI DRV8870 (which could tolerate 3.6 amps, but is rated for 6.5 volts up. So it would need to be tested if it works with a single-cell lipo). Second, I was thinking about the user interface to adjust times. Instead of an external programming device, maybe two dip switches would suffice. One would choose between normal (20s motor run, 90sec DT) and fly-off (10s motor run and 120sec max) flight settings, the other would set either normal flights (as before) or DT 5 sec after motor stop for trimming.

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« Reply #846 on: January 28, 2020, 10:33:32 AM »

Liav Hershkoviz might be helpful to bounce ideas back and forth.  He has a line of "Tiny Timers".  Liav Hershkoviz <[email protected]> Not intended as a promo.  Wink
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Tapio Linkosalo
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« Reply #847 on: May 31, 2020, 03:32:01 AM »


Here is my first attempt on E-20 prop. I had no previous idea of how much pitch or blade width, so the blades are just constant chord (6mm) and the pitch is 45mm (1.8"). Will have to test fly this to see if it works, and the refine design.

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Tapio Linkosalo
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« Reply #848 on: June 08, 2020, 03:42:48 AM »

Finished my first E-20. Fuselage dimensions as in Puzzle E-36 with wing and tail stretched from Ellipse CLG, but routed out of Depron. I'll try the model without any carbon reinforcements as it seems the wings might be stiff enough as they are.

The model timer is based on my P-30 timer. But instead of driving a servo it controls a sort-of home-made "ESC" (that is as described before, two FETs that either drive the motor or short-circuit it for brake). The P-30 timer has another FET to turn on and off the servo power, and this FET is then taken to new use to trigger a band-burner for DT (on another separate piece of PCB). If all these three work together, then the next step is to integrate the three to one PCB.

Also I have to figure out what size of battery to use and where to install it. Maybe underneath the fuselage.

The current prop is a GWS 3020 (I need to shorten it a bit for 2.6"), but eventually I'll need to 3D print a folder.

Weight as presented is 30.5 grams. Nice!
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Yak 52
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« Reply #849 on: June 08, 2020, 06:06:43 AM »

Very cool Tapio  Cool

Your timer/ESC sound similars in concept to my own (unfinished) developments.

I like the motor/boom mount. Did you print it?


Jon
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