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Old Nov 03, 2010, 07:46 PM
Flying = Falling (Slowly)
dharban's Avatar
Tulsa, OK
Joined May 2004
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eSupra Build Log

I just received my eSupra Ultralight which I intend to fly and test for Altitude Limited Electric Soaring events. I did not select this plane because I necessarily believed that it was an optimum plane for these events, but to compare it with other types of planes that I have which might also be suitable including a Radian, an Electron F5J and an E-AVA. I also selected it because I fly and am familiar with the Supra TD glider. I fly a regular Supra and Supra Carbon Light. I enjoy flying the plane and it has many properties that might make it suited for ALES events.

My selection of a plane for ALES competition included the following criteria:

1. ALES competition right now is defined by its launch being limited to the lesser of 200 meters and/or 30 seconds motor run time. The intent is to equalize launch heights and to have competitions decided by gliding/soaring time and landing skill. My first criterion was a plane that would retain the gliding/soaring/landing abilities of existing TD competition planes. To me, this requires that for any particular design, a minimum weight penalty from the chosen power system. In this case, my objective is to build an electric Supra with a flying weight somewhere between that of my standard Supra and of my Carbon Light Supra.

2. While ALES competitions will emulate our TD flying for the most part, there will be at least one important difference. While it can be argued that TD launch altitudes can be more or less equal among similarly skilled competitors, the point at which gliding/soaring begins is much more limited in lateral extent in current TD flying than ALES flying will allow. Even relatively modestly powered planes will be able to fly a quarter of a mile or more away from the launch point while climbing the 200 meter altitude cut-off point. I have selected a power system that, I hope, will allow this plane to fly 1200 lateral feet or more into a 20 mph wind while climbing to cut-off altitude with the equivalent of about 12 oz. of ballast.

3. I want a plane that is easy and fun to fly. One of the things that I have experienced with other electric planes is the pleasure of having the “right” amount of power when the plane leaves my hands. None of my planes is difficult to handle on launch. None has so much power that it is the least bit iffy when I release it. On the other hand they all have enough power to launch simply. I hold the plane overhead, turn on the motor and let go. It flies straight away without any fuss – no worry about a stall.

So, after a bit of thought, I have chosen to do everything (or almost everything) I could do to keep the weight of the plane down. I fudged a little on the motor selection simply because I liked the robust design of the motor I chose. The power system I am using consists of an MVVS 690 Glider motor, two Hyperion 1900 mah 2S packs in series, a Castle Creations ICE 75 amp ESC/BEC, one of Vladimir’s spinners and a 17 x 8 Aeronaut propeller. On the bench, this combination runs at 700 watts of input (50 amps), 6900 RPM and 125 oz. of thrust. The battery pack is rated at 45C for continuous operation (85.5 amps).

The radio and control system consists of an Airtronics 92104 receiver, and Hyperion servos all around (DS095FMD for elevator, DS09AMD for rudder, DS11AMB’s for flaps and ailerons. Radio system power will come from the ICE 75 ESC/BEC. While I am may be living on the edge here, I am sort of going one step at a time in this direction. I have tested the servos and they can each draw about 0.6 amps when stalled (3.6 amps total). Before it hits the air, I intend to bench test the setup and then to test it in a more disposable plane. In the course of testing the motor/battery/ESC/prop combination I have selected, the 4S 45C battery pack could not be drawn down to anywhere near the 4.8 V. minimum receiver voltage. And in normal operation, the maximum battery load is substantially below its continuous rating. In addition, I use a battery care regimen that substantially reduces the possibility of a sudden and unexpected failure – I log individual cell voltage and pack resistance for every charge. I am approaching this carefully, but am ultimately interested in seeing if this equipment will do what it is supposed to do. This is a test of the ability to keep AUW to a minimum (even if I did select a motor that is a little heavier than some other similarly powerful motors).

So I got the package yesterday and have weighed the various components to see how close I can come to my objective of more or less matching the weights of my TD gliders. The results of all of that weighing will be reported in the next blog.

More details on the build can be found on the ALES group on Yahoo (RCALES).

Happy Landings,

Don
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Old Nov 03, 2010, 09:48 PM
Registered User
Blenheim, NZ
Joined Dec 2007
1,164 Posts
Looks great

It is hard to imagine a better machine for what you are planning to do Don. The Supra is simply outstanding in TD as you know. Having an electric one at the same loading should assure it will still turn tight and thermal on HLG air. I fly a Perfect myself but do recognise the Supra's outstanding performance.
I also like the altitude limiting idea to return the emphasise to thermalling. The gentle launch method must save a heap of wing structure weight which probably means it will handle even better than the TD version. I look forward to seeing your coments as you get this one flying.

Allan Knox in NZ
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Old Nov 04, 2010, 08:01 AM
You looking at me?
Ed Franz's Avatar
USA, KY, Burlington
Joined Sep 2001
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I personally would not use a BEC on a six servo plane. A separate battery pack would be safer option. But, that is just my opinion.

Ed
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Old Nov 04, 2010, 08:39 AM
Flying = Falling (Slowly)
dharban's Avatar
Tulsa, OK
Joined May 2004
2,645 Posts
Quote:
Originally Posted by Ed Franz View Post
I personally would not use a BEC on a six servo plane. A separate battery pack would be safer option. But, that is just my opinion.

Ed
Ed,

I have my concerns too. I have used separate batteries in the past. Right now I mostly use a separate switching BEC. In this application I am interested in using the Castle Creations ICE because it has a built-n switching BEC (previous CC ESCs used linear BEC's which become less functional as battery pack voltages go up.

I would not consider using this configuration with the servo line-up that I use in my regular TD planes, but all of the servos in this plane will be Micro-Servos. I have tested all of them for current drain at stall and if they were all fully loaded, the total load could not approach even the rated load for the built-in BEC. Inasmuch as I am looking for simplicity, I have sized everything so that I will never be operating near the rated limits of the electrical components. By going with a 4S system, my max amps are around 50 where the ESC is rated at 75 amps and the battery load never exceeds the Continuous Duty rating for the battery. The other thing about the 4S system is that even when the pack is instantly loaded, the measured voltage drop for the initial surge keeps the voltage to the ESC well in excess of the voltage necessary to keep the receiver from dropping out. So far, on the bench none of the components gets past "warm" to the touch when simulating ALES flying (30 seconds of "on" every 5 minutes). (One of the added beauties of ALES over "hotliner" flying.)

One of the differences between this ALES flying and TD flying is that the flying loads are substantially diminished -- especially on launch. Planes are being built which are lighter than their TD counterparts. The Supra Ultralight actually has a "molded-in reminder" that says "careful, electric thermalling only."

I have a pretty extensive bench test setup where I can subject the system to artificial loads higher than the expected electrical loads I can get while flying. And the plane will be ground tested extensively.

Finally, since I switched to the Hyperion charger, every time I charge, discharge for storage or cycle a battery on the bench (which is before and after every flying session) I get a plot of individual cell performance during charge and discharge and a plot of pack Internal Resistance. I have gotten into the habit of tossing batteries that I suspect most people would fly for another season -- even on my TD planes. I got into this habit a couple of years ago when I started experimenting with plotting battery charge/discharge cycles and learned that relying on a single beep or flashing light or even the single number of Amps in or out will not always show you a failing battery.

I would not quarrel with people who have experienced catastrophic failures with any particular set-up. And I suspect using a separate receiver battery is somewhat safer, but it is worth noting that the separate battery is not "redundant" -- it is just a different component subject to fail and whose reliability is ultimately a function of one's willingness to be as paranoid about it as you would be to the rest of the systems in the plane.

Basically, this is an experiment to see how this stuff works.

Happy Landings,

Don
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Old Nov 04, 2010, 10:05 AM
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Interesting thread, with underlying discussion, internal ESC BEC versus external BEC/separate battery pack.

I have the ICE LITE ESCs , both ICE 100 and ICE 50 flying on various airframes, all with micro servos powered by the ESC BEC. As Don points out, the BEC in these ESCs are 5 amp switching BECs, so they are not feeding heat into the ESC like the previous linear ones, as they step down the voltage.
The ICE series of speed controllers also allow one to monitor voltage drop, ESC temperature, ripple voltage and other factors as they occur during a series of flight in real time. This helps one to study voltage, discharge rate, of a LiPo after a flight in great detail. I also check individual cell voltages after a flight, with my TP 1010 charger, looking for trouble, before I start charging a LiPo.
Finally you have a very large (in my case 6.5mm plugs) connectors from LiPo to ESC, just one set of connectors and one battery to worry about. I too replace my Lipos often, and replace them at the start of every season, for the expensive/complex ships. I have been very pleased with the new Thunder Power 45C packs, though I still charge them at the conservative, 1C rate. As a last resort, in flight (if you run the motor occasionally) the LVC will warn you if pack voltage has fallen below say 10 volts for a 3S pack. The motor will surge, or cut out in this case

my 2c worth
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Old Nov 04, 2010, 10:51 AM
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Terre Haute, Indiana, USA
Joined Aug 2004
959 Posts
Don,

Can you fit your 4-cell pack through the hatch? From the photo, the hatch seems pretty small, but maybe it is actually bigger than it looks.

That E-Supra is a very desirable plane indeed. I Look forward to more details. Could you provide a link to the Yahoo site that you mentioned earlier?

Thanks,

FF
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Old Nov 04, 2010, 11:20 AM
Flying = Falling (Slowly)
dharban's Avatar
Tulsa, OK
Joined May 2004
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Quote:
Originally Posted by Forest Flyer View Post
Don,

Can you fit your 4-cell pack through the hatch? From the photo, the hatch seems pretty small, but maybe it is actually bigger than it looks.

That E-Supra is a very desirable plane indeed. I Look forward to more details. Could you provide a link to the Yahoo site that you mentioned earlier?

Thanks,

FF
Actually, I am using two 2S packs in series. I have had good luck with Hyperion batteries and 1900 mah 45C packs were not available in the 4S configuration.

Happy Landings,

Don
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Old Nov 05, 2010, 10:21 AM
Flying = Falling (Slowly)
dharban's Avatar
Tulsa, OK
Joined May 2004
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Well, as I mentioned in the last post, my first objective with this plane was to come up with a plane which would come out somewhere between the weight of my Supra and of my Supra Carbon Light using the MVVS 690 Glider motor. While I did not immediately achieve that objective, I came close and discovered some interesting things about putting together a competitive plane.

As I mentioned, I decided early on to go with a power system which consisted of an MVVS 690 Glider motor, a Castle Creations ICELite 75 ESC, a battery system consisting of two 2S-1900 mah Hyperion battery packs and a 17x8 Aeronaut prop and 30mm Vladimir Spinner. I decided to go with a Hyperion 095 servo for the elevator and a Hyperion 09 servo for the rudder (both in the tail).

I started the construction process by mounting all of this up in the plane and fabricating the wiring harness so I could accurately balance the plane (95mm behind the L.E.). I had selected the 1900 mah battery pack as a compromise between the smallest pack which might work and one which would give me a couple or three launches. I had hoped that I could achieve a balance by shifting the battery. But it was not to be. The power system, combined with the shape of the Supra fuselage resulted in a nose heavy plane which required a 45 gram weight in the tail to balance it. Fortunately, I was able to fabricate a brass weight which will also facilitate fastening the rudder to the boom while maintaining its removability. (see photo). Unfortunately, the plane now projected to come out a little heavier than I would have liked.

Stock Supra Weight 1787 gms 63 oz
Carbon Light Supra Weight 1845 gms 65 oz
eSupra w/MVVS 1940 gms 69 oz

While this is a little disappointing, it more or less corresponds to the weight at which I fly my stock Supra with ballast for 13-14 mph wind.

Nonetheless, I have not abandoned my desire to have a lighter weight competitive plane. So I scrounged around my boxes of unused stuff and found a Neu 1105-2Y-3800 that I had used in a hotliner which I really hated. I determined that I could replace the 4.4 Maxon gearbox with a 6.7 gearbox, go with an 1100 mah 4S pack, a CC IceLite 50 ESC and a bit smaller prop and reduce the plane weight by 278 gms (9.8 oz) and come up with a 1662 gm (59.2 oz) plane.

Now, this comes with a price – less thrust. The MVVS system is about a 700 watt system which will pull a static thrust of around 3600 gms. I expect the Neu system would be closer to 500 watts and 2700 gms thrust (the wattage may not tell the entire story though, because the Neu motor will be operating in a more efficient range and the prop will also be operating in a more efficient range). So I decided to solve my dilemma by accepting both solutions. I have ordered a second nosecone and will set-up both systems – one for windy conditions and one for light conditions. We will see how it works out.

Lest someone cry foul that this is an excessively expensive add-on to an already expensive plane, I would suggest that there are some very good outrunners which could deliver 500 or so watts for a similar weight and which are substantially less costly than the geared inrunners. I have been running a Hyperion 3250 in my AVA for some time now and these motors are powerful and reliable. They also have tapered nose pieces which facilitate installation in smaller nosecones. They do, however require that the motor wires be run outside the nosecone and then back in to allow the rotating part of the motor to clear the wires. Anyway, that’s where we stand today.

Happy Landings,

Don
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Old Nov 06, 2010, 02:58 PM
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Manchester, UK
Joined Feb 2009
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Hi Don

Thanks for starting an e-Supra build thread - great timing as I'm just getting to grips with mine at the moment. Last season I flew its 2m little brother Sprite in our UK Height Limited comps and was very impressed with the performance of the e-Supra in the Open class. (Height limited comps are becoming really popular over this side of the pond so I'm pleased to see that you guys are trying them out too).

I've used one of those beautiful MVVS 5.6 (690kv) Glider motors before in an Ava. They're superb motors but a tad on the heavy side as you've found out. For the Supra I've put together a HET 2W 25 (2660kv) inrunner with a 6.7:1 gbox to be run on 4S. This combination offers a decent efficient range of 16" to 18" props to pull between 450 - 700W if the simulation calcs are to be believed. The motor and gbox combination works out at around £100/$160 so it's not in Neu financial territory! Again like you I may need to resort to making up a 1500 - 1800 mAh 4S unit from a couple of 2S cells as there's not a wide choice of small capacity 4S lipos is there?

However, this is rather getting ahead of myself as I've only just finished fixing in the tail servos so far. Looking at them I wonder if I've made an error of judgement as I've used my favourite Hyperion DS09AMD 2kg.cm digital servos for both rudder and elevator to keep the weight low where it counts. Now I'm wondering if I should have used a more powerful DS095 4kg.cm item for the elevator and just lived with the extra weight. Granted it's intended for TD work not aerobatics, but there's still this nagging doubt! So any comments from out there in RC-land on the wisdom of my choice would be welcome!

Enjoy flying

Skip
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Old Nov 06, 2010, 07:42 PM
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Old Nov 07, 2010, 12:50 PM
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Originally Posted by SkipT35 View Post
Looking at them I wonder if I've made an error of judgement as I've used my favourite Hyperion DS09AMD 2kg.cm digital servos for both rudder and elevator to keep the weight low where it counts. Now I'm wondering if I should have used a more powerful DS095 4kg.cm item for the elevator and just lived with the extra weight.
Don't worry Brett/Skip, the DS09AMD will be totally fine for the elevator. I have flown my Supra-e with them very happily. OTOH as Don has found out, it is hard to make a powertrain so light that tail weight isn't required, so it could be argued that the few grams extra weight of the DS095 makes more sense than carrying ballast.

BTW Don I would recommend smaller capacity batteries, when I was flying my last Supra-e on a 4S setup I used a 1.3ah battery, and I now use a 1.8ah 3S setup. With the latest high discharge cells I would go to an even lower capacity, as (from memory) a low angle/ranging climb to 200m only uses about 250mAh (on 3S).

Neil.
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Old Nov 07, 2010, 01:01 PM
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Manchester, UK
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Hi Neil

Thanks for the reassurance. I thought I remembered you saying you'd used a DS09 on the elevator on your model. However, I hadn't realised when making the decision that the extra weight of a DS095 might not be such a penalty after all. C'est la vie! Maybe it's time to try my hand at micro-surgery again!

Enjoy flying

Skip
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Old Nov 07, 2010, 06:15 PM
Flying = Falling (Slowly)
dharban's Avatar
Tulsa, OK
Joined May 2004
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Quote:
Originally Posted by Neil Stainton View Post
Don't worry Brett/Skip, the DS09AMD will be totally fine for the elevator. I have flown my Supra-e with them very happily. OTOH as Don has found out, it is hard to make a powertrain so light that tail weight isn't required, so it could be argued that the few grams extra weight of the DS095 makes more sense than carrying ballast.

BTW Don I would recommend smaller capacity batteries, when I was flying my last Supra-e on a 4S setup I used a 1.3ah battery, and I now use a 1.8ah 3S setup. With the latest high discharge cells I would go to an even lower capacity, as (from memory) a low angle/ranging climb to 200m only uses about 250mAh (on 3S).

Neil.
Neil,
You are correct concerning my reasoning behind using the DS095 for the elevator. While I AM trying to get to some kind of minimum weight, the difference offered by the single 095 in combination with the 09 just wasn't worth fighting. I reasoned that using a servo with which I was not familiar for the rudder might not result in a fatal outcome since I would still have ailerons to get me home. I guess we will see.

I agree that, for competition, the smaller packs are great. The base, and apparently heavy motor combination I selected (MVVS) has an input wattage of around 700 watts. I decided to give myself a little slack to allow multiple relights for sport and practice flying. And given my bench test results this will facilitate brisk enough performance to fly into the high winds that we often have here.

That being said, I will be testing a minimum weight 500 watt system which will use a minimum size battery (maybe less than 1100 4S for single competition launches. If my calculations are correct this will result in an all up flying weight which is less than a stock Supra glider. We'll see.

Happy Landings,

Don
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Old Jul 25, 2011, 12:25 PM
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Madrid, Spain
Joined Feb 2005
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Hello Don, how are you going with the Supra? What about motors used? Which is the current weight?

Looks like it's great bird and I'm thinking about all components for a new one. I already have flown a Pulsar 3200 for a whole year and preparing a new one. But one esupra is a big step for me ...

Thanks, Javier.
Quote:
Originally Posted by dharban View Post
Neil,
You are correct concerning my reasoning behind using the DS095 for the elevator. While I AM trying to get to some kind of minimum weight, the difference offered by the single 095 in combination with the 09 just wasn't worth fighting. I reasoned that using a servo with which I was not familiar for the rudder might not result in a fatal outcome since I would still have ailerons to get me home. I guess we will see.

I agree that, for competition, the smaller packs are great. The base, and apparently heavy motor combination I selected (MVVS) has an input wattage of around 700 watts. I decided to give myself a little slack to allow multiple relights for sport and practice flying. And given my bench test results this will facilitate brisk enough performance to fly into the high winds that we often have here.

That being said, I will be testing a minimum weight 500 watt system which will use a minimum size battery (maybe less than 1100 4S for single competition launches. If my calculations are correct this will result in an all up flying weight which is less than a stock Supra glider. We'll see.

Happy Landings,

Don
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Old Jul 26, 2011, 06:40 AM
Flying = Falling (Slowly)
dharban's Avatar
Tulsa, OK
Joined May 2004
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Quote:
Originally Posted by jawarejj View Post
Hello Don, how are you going with the Supra? What about motors used? Which is the current weight?

Looks like it's great bird and I'm thinking about all components for a new one. I already have flown a Pulsar 3200 for a whole year and preparing a new one. But one esupra is a big step for me ...

Thanks, Javier.
Javier,

I am currently using an MVVS 5.6 690 glider motor and a Thunderpower 1300 4S 65C battery. The plane weighs 71 ounces all up. It flies nicely, but I would like more power and less weight. I have ordered a Neu 1110 with a gearbox. This will allow me to take an ounce out of the tail, to reduce the all up weight to about 67 oz. and to increase the power by 30 percent or so.

The MVVS is a beautiful glider motor -- it is just too heavy for a long nosed plane. I strongly recommend using a motor that weighs 6.5 oz. or less and the 1300 4S 65C battery to get the plane to minimum weight. An efficient motor with 900 or so watts of input will result in a very nice launching and gliding plane.

Happy Landings,

Don
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