Author Topic: 1/2 A Electric--first try (Read 10818 times)

Alan Hahn · « **on:** February 12, 2008, 08:20:08 PM »

Here is a photo of something I have been playing around with. The plane is a Brodak Baby Clown ARF which has been pressed into service. The total system is being developed to fly in Jim Renkar's "It's Only a Hobby" 1/2 A contest. Jim said I could fly electric as long as the prop was 6 inches in diameter or less.

This is one of three small motors I have wound myself. The other two I just finished up and can swap out if the tiny little one is too weak. I am trying to use a Thunderpower Lite 2s1p 730mAHr battery which weighs just over an ounce. The ESC is a CC Thunderbird 9A. Timer is a JMP-2. Weight of the power components (including battery) is basically the same weight as a Cox Black Widow (2.1oz) with tank and prop, but no fuel.

Alan Hahn · « **Reply #1 on:** February 12, 2008, 08:38:02 PM »

Here are a couple of other picts of the 2 other backup motors. These are larger (22mm stator size) and based on a DVD motor. Also shown up in left corner is my Brodak Super Clown motor, now being modified!

Also shown here is some of my test stuff, an Astro Servo tester to provide throttle, an AstroWhattmeter to measure (static) currents and battery voltages, and also the Thunderbird 9A ESC and an EVO 2s1p 2500mAHr Lipo to provide power. I use this, along with a tach to see how my particular winding is working. Current draws are in the 5A to 7A range with these props. Of the three motors, the small one on the Baby Clown is wound 16 turns of 26 gauge wire, the one in the lower photo not hooked up to the ESC is wound 14 turns of 24 gauge wire, and the 3rd is 11 turns of 22 gauge wire. The last is the hottest wind (rpm/volt) and is my best guess as the most adequate to replace the COx Blackwidow.

We will see!

bfrog · « **Reply #2 on:** February 12, 2008, 10:17:35 PM »

Alan,

Looks very interesting. Please post when you have some flight data. I would be very interested to see how this setup works.

I have been flying some 1/2A sized planes but use a bit more power. 8 to 9 amps on 3 cells. I also use much large props, 8 or 9" diameter. I am curious how you plane and motor combo work.

Bob

Alan Hahn · « **Reply #3 on:** February 13, 2008, 08:18:30 AM »

Bob,
Waiting for this to go away!

As I mentioned, the challenge from Jim is to use a 6 inch prop.

Mike Spiess · « **Reply #4 on:** February 13, 2008, 11:13:11 AM »

Looks like a pefect flying day with all that smooth white "sand". When I was a kid I use to fly off alot snow just had a hard time finding willing stoges.

Alan Hahn · « **Reply #5 on:** February 13, 2008, 12:20:21 PM »

Well I don't mind the snow as much as the 14^oF temps! As proof check out this link
http://stunthanger.com/smf/index.php?topic=4289.0

But you are basically correct about one point, my stooge isn't here this week! (Right Fred?)

Mike Anderson · « **Reply #6 on:** February 17, 2008, 10:37:28 AM »

Quote from: bfrog on February 12, 2008, 10:17:35 PM

Alan,

Looks very interesting. Please post when you have some flight data. I would be very interested to see how this setup works.

I have been flying some 1/2A sized planes but use a bit more power. 8 to 9 amps on 3 cells. I also use much large props, 8 or 9" diameter. I am curious how you plane and motor combo work.

Bob

Bob and Alan:

Here is something that I "threw together" the last couple of nights - triggered by
discussions on 3 different groups.

It is my "1/2E" Skyray in it's newest version. The thing about this particular
setup is it won't meet the 6 inch prop rule. Both of the motors that I have are
too low a Kv, but there are others available in the same "cheap" brand which
should work with smaller props.

The flight programmer (I'm not calling them "timers" anymore - they do much more
than that) is from Will Hubin (See other posts in this forum) and I like it a lot.
Will has reprogrammed mine a couple of times, based on my particular equipment
and is very interested in getting an easy to use and versatile programmer into
circulation. The motor(s) will run on 2-cell, 900 mah packs that I got from
dealextreme.com for <$7 each, free shipping. Well, that I ordered, but am still
waiting for. The motor that is mounted and the 18Amp ESC cost $16, as a
combo. All up weight, with the 900's should be right at 8 oz.

Mike@

Alan Hahn · « **Reply #7 on:** February 17, 2008, 06:28:08 PM »

That's a neat looking SkyRay.

I ordered a Thunder Tiger Prolite 2s730 but still am waiting for arrival too. Up to now I can just make static runs.

I was also thinking about Will's timers, but first thought I'd see where I am with this project before ordering a couple.

bfrog · « **Reply #8 on:** February 17, 2008, 10:03:20 PM »

Mike,

Nice looking. Have you flown it yet? I like the battery compartment.

What kind of motor are you using? What's the source? I was just about to order a couple of the combo's at United Hobbies in Hong Kong. I have been playing with a couple of 1/2E (I like that tag you used) the last two weekends. I'll take some pics this week and post them. They are both depron foamies but one has a built up semi-symetrical airfoil. I had a couple of guys that are better flyers than me have a turn and they all said they flew very well. I want to see if I can improve them and get a reasonably price package. I have been using Thunder Power batteries but want to try some cheaper ones.

Bob

Mike Anderson · « **Reply #9 on:** February 17, 2008, 11:27:34 PM »

Quote from: bfrog on February 17, 2008, 10:03:20 PM

Mike,

Nice looking. Have you flown it yet? I like the battery compartment.

What kind of motor are you using? What's the source? I was just about to order a couple of the combo's at United Hobbies in Hong Kong. I have been playing with a couple of 1/2E (I like that tag you used) the last two weekends. I'll take some pics this week and post them. They are both depron foamies but one has a built up semi-symetrical airfoil. I had a couple of guys that are better flyers than me have a turn and they all said they flew very well. I want to see if I can improve them and get a reasonably price package. I have been using Thunder Power batteries but want to try some cheaper ones.

Bob

Thanks - no haven't yet flown it (see the picture that Alan posted -- the one of the snow? That is also my world, at this time. With more predicted on the way.) So it hangs it the basement, for now. I do have it sketched up, so if it flies OK, I can e-mail .dxf or .dwg plans.

I've been dealing with lightflightrc.com - he carries the same line of cheap outrunners that BP (and others) carry, with excellent prices. (I think he is near you, Bob. Belmont, CA?) These motors are mediocre in consistency and quality, and according to Dave at Lightflight they are prone to have one batch be good, then the next batch will have things like wrong screws. But for the prices, it is something to play with. But, frankly, I like the ESC's that he lists as "Suppo" brand - they have enough features for control line - and they are bringing out some with governors. In fact, he lists a 30Amp helicopter version for $19 - but it's out of stock at present. I'm still in the mode of "Let's see what we can fly" so absolute Contest Performance is nowhere near the top of the list. If I like what this does, I can always get a Scorpion to put on it.

For motors, I got one of his "Cheap combo's" - listed as a 2208-14 w/ an 18Amp ESC- $16. How can you NOT buy something like that? I also got a 2208-12 (the gold motor in one photo) which weighs the same and fits the same mounting holes - has a higher Kv than the "cheap" -14. But both, when running with props that are reasonable for their Kv are obviously going to fly the plane. Beyond that, I just don't know yet. The -12 turns a 7-6 Taipan, cut to 6-6 at 11000 RPM, drawing about 8 amps (IIRC). The -14 seems to like an 8-3 Master Airscrew, turns it about 8500 @ 8 amp. For a motor that would work with the "6 inch rule", look at the 2208-6 or the 2212-10 on 3 cells.

If you order from United, watch the "in stock quantity numbers" - right now they are out of almost everything that I considered buying. I broke down and ordered some LiPos, Props and hardware from Hobbycity/United Hobby - that was just before all of Hong Kong shut down for the Chinese New Year - latest word is that my stuff has left the Hong Kong post office, so that is encouraging. The 2-cell packs I ordered from dealextreme.com - also a Hong Kong mail order house - that were under $7 each in qty's of 3 and have free shipping. Then THEY also went on vacation, and I've had a couple of "in process" notifications from them, but no batteries yet. No hurry though, based on the weather forecasts. If they aren't absolute garbage (and they have pretty fair reviews if the reviews are real), I'd consider getting half a dozen or so, and making up 2s2p and/or 3s1p packs with them. I may make up some charging harnesses so that I can fool the FMA CellPro into charging more than one at a time, too. Well, that about covers the trailing edge of technology here in the frozen Midwest.

bfrog · « **Reply #10 on:** February 18, 2008, 10:20:49 PM »

Mike,

Thanks for the input. I did place an order today at United Hobbies. We'll see how they work. I know about the back order problems so I made sure they had stock. I plane to build a new airplane to test these inexpensive combos and see how they work.

Bob

Archie Adamisin · « **Reply #11 on:** February 19, 2008, 07:49:19 AM »

I have ordered a bunch of stuff from Hobby-City and you will not be disappointed. I have been following this thread with interest and was wondering if anyone has considered an in-runner? I have a hextronik#2040 (380L) 2080 Kv in-runner from Hobby-city and it turns a 5.5 x 4.5 @ 14,000 rpm @ 10.5 amps on (3) 1000's LiPoly's. If you fly on 42' lines with a model around 200 square inches, you should have a winner with that and maintain the 1/2 A 6" prop rule and fly just like a Cox powered 1/2 A without the hassle. Hobby city has this size motor in (3) different Kv's. I use the Tower-pro 18 amp controller or the Turnigy 18 amp controller with governor that can be programmed using the available programming card. The in-runner will also run more efficient than the out-runner @ that higher rpms required.

Just my 2 cents.

Archie Adamisin

Muncie, Indiana

Mike Anderson · « **Reply #12 on:** February 19, 2008, 08:21:14 AM »

Quote from: Archie Adamisin on February 19, 2008, 07:49:19 AM

.... I use the Tower-pro 18 amp controller or the Turnigy 18 amp controller with governor that can be programmed using the available programming card. The in-runner will also run more efficient than the out-runner @ that higher rpms required.
....

Archie Adamisin

Muncie, Indiana

I've been trying to find out which ESC's on that site have "governor" mode and which
do not. Are you saying that only the Turnigy has it? One thing that I've found out
is that sometimes they list "helicopter" mode, and that only means that it has a
"super soft start" option. The programming card says "Governor mode on-off" but it
looks as though not all of the ESC's that will work with that card have it.

As to the inrunner possibly being a better choice, you are probably correct ... if one
is going to take 1/2E stunt very seriously and is limited to the small props.

Mike@

Archie Adamisin · « **Reply #13 on:** February 19, 2008, 09:12:56 AM »

Mike,

I have (2) Turnigy controllers and am testing the governor. I haven't got to fly them yet (DARN WINTER WEATHER

), but bench testing looks promicing. The programming card is very easy to use and the throttle response and brake are very smooth. The motors also react to timing advance changes unlike some other controllers. I am happy so far, but we'll see what happens when they get in the air. I plan to test the 60 amp Sentry controller in the Oriental and I have a 10 amp that I'll test on my indoor flat foam stunter. Can't beat the price on these things. Most desirable is the ability to arm the brake and governor at the same time.

Archie Adamisin

Muncie, Indiana

bfrog · « **Reply #14 on:** February 19, 2008, 09:33:09 AM »

Mike,

On your 1/2E plane, what props are you using? How are you attaching them to the shaft? I am afraid with the small diameter shafts that on landing it will be very easy to bend the prop shaft.

I also notice in your pictures that the motor mounted in the plane on the top photo is different than the one you show laying next to the plane in a later photo. The seem to have different mounting schemes. Are you trying both out? If so how do you mount the different patterns?

Bob

Mike Anderson · « **Reply #15 on:** February 19, 2008, 10:38:55 AM »

Quote from: bfrog on February 19, 2008, 09:33:09 AM

Mike,

On your 1/2E plane, what props are you using? How are you attaching them to the shaft? I am afraid with the small diameter shafts that on landing it will be very easy to bend the prop shaft.

I also notice in your pictures that the motor mounted in the plane on the top photo is different than the one you show laying next to the plane in a later photo. The seem to have different mounting schemes. Are you trying both out? If so how do you mount the different patterns?

Bob

I'm not sure yet about props. There are two different motors - the "Cheap Combo" is a 2208-14 (Kv = 1450) -
I'm going to start with the black MA 8-3 that is in the pix.
The other motor is the 2208-12, and yes it does look a bit different - frankly it doesn't look as cheap. But it weighs
the same and when both are mounted on X-style mounts, they are the same length.
The cheap combo one has a 3 mm threaded shaft and a couple of nylon lock nuts - I had to jury rig a little prop
driver (from a 6-32 blind nut).
The "not quite as cheap" motor has a regular collet type of adapter and a 4 mm shaft.

Frankly, if using them as they are now set up, they may bend the shaft. Or they may tear the whole firewall out.
I'll probably put some type of skid under it, when the flying season gets a little closer. Then experiment with a
"prop saver" like Alan shows at the top of this thread.

I'll attach some pix of the motors from the web site.

Mike Anderson · « **Reply #16 on:** February 19, 2008, 10:44:49 AM »

Quote from: Archie Adamisin on February 19, 2008, 09:12:56 AM

Mike,

I have (2) Turnigy controllers and am testing the governor. I haven't got to fly them yet (DARN WINTER WEATHER ), but bench testing looks promicing. The programming card is very easy to use and the throttle response and brake are very smooth. The motors also react to timing advance changes unlike some other controllers. I am happy so far, but we'll see what happens when they get in the air. I plan to test the 60 amp Sentry controller in the Oriental and I have a 10 amp that I'll test on my indoor flat foam stunter. Can't beat the price on these things. Most desirable is the ability to arm the brake and governor at the same time.

Archie Adamisin

Muncie, Indiana

Thanks for the info -- So the Sentry model definitely has the governor (and brake? cool ....) .

That means I'll be doing another Hobbycity order soon - I also want to play with one of the larger motors. I should probably get some kind of plane built for them ...

Alan Hahn · « **Reply #17 on:** February 19, 2008, 11:42:05 AM »

Archie,
I am curious about your inrunner---when you say 14krpm with 3s, is that full throttle or partial. Just curious.

On my GBx1 with an APC E 5.5x4.5 prop (the one hooked up to the ESC in the photo above), I'm turning about 13krpm with a 2s2500 battery (7.4V indicated @ 9.3A)---at full throttle. I haven't actually calculated kV yet with that one. As I think I mentioned somewhere, I am still waiting on the arrival of my ThunderPower Lite 2s730 battery (1.1 oz). As soon as I get it, I'll drag Fred K. out to the field for a flight.

I am aware of Hobby City, however I feel very strongly about BOM (Builder of the Motor)! And it's just so darn fun to wind these little guys.

Archie Adamisin · « **Reply #18 on:** February 19, 2008, 06:19:16 PM »

Alan,

The Hextronik (Turnigy) #2040 (380L) 2080 Kv turns the 5.5 x 4.5 APC E @ 14,800 @ 10.9 amps static full throttle on a 3s 1000 Loong Maxx 15C pack. It has the same front mount pattern as a Graupner speed 400 or Astro brushless 01/02/05. It has a 2.3 mm output shaft like a speed 400. It weighs 65 grams with a Graupner CAM speed spinner & prop. I bought this motor to fly in a speed 400 racer and see how fast I could go with 115 watts. Hobby City has (3) different Kv's in this size. (2080, 3500, & 4700)

I wish I had the time to wind my own motors. I have to trust that these motor manufactures know what they are doing and I'll stick with airframe design.

Archie Adamisin

Muncie, Indiana

Alan Hahn · « **Reply #19 on:** February 19, 2008, 06:45:08 PM »

Archie,
I did some more careful measurements on my 38.5g motor and posted it here.
http://forum.gobrushless.com/showthread.php?t=4683

My kV is ~2250.

One comment about motor quality, the one thing I can do is to cram in most amount of copper to gain efficiency.

But I guess I do enjoy this more than airplane design, so I guess it is different strokes for different folks!

Mike Anderson · « **Reply #20 on:** February 25, 2008, 09:00:54 AM »

Quote from: Archie Adamisin on February 19, 2008, 09:12:56 AM

Mike,

I have (2) Turnigy controllers and am testing the governor. I haven't got to fly them yet (DARN WINTER WEATHER ), but bench testing looks promicing. The programming card is very easy to use and the throttle response and brake are very smooth. The motors also react to timing advance changes unlike some other controllers. I am happy so far, but we'll see what happens when they get in the air. I plan to test the 60 amp Sentry controller in the Oriental and I have a 10 amp that I'll test on my indoor flat foam stunter. Can't beat the price on these things. Most desirable is the ability to arm the brake and governor at the same time.

Archie Adamisin

Muncie, Indiana

Archie-

I'm still trying to figure out this Governor stuff - I got a "HQControl" ESC - 40 Amp - from the want-ads
at RCGroups - it comes with a little blue box programming unit. Down the list of options are -
Governor - and you can choose Off, Lo or Hi. But I'm not able to see any results of the Governor setting
when I run a motor - RPM still drops off as the battery voltage sags, Loading the motor a bit while its
running by adding some drag with my thumb on the bell housing (trying to simulate going into a maneuver)
doesn't seem to do anything.

My question is, have you got the Turnigy ESC Governor function to work the way you want it to - or
at least the way you think it should work - and how do you test it ? What should a person be seeing?

Mike A

Mike Anderson · « **Reply #21 on:** February 25, 2008, 09:07:50 AM »

Oh - what changes are you seeing with "timing advance" also? I've never seen
that really change much either --

@

Alan Hahn · « **Reply #22 on:** February 25, 2008, 01:18:39 PM »

Mike,
About the governor mode
If you are running on the bench, then I would not expect to see anything unless you try to increase the load---like you mention bt putting some drag on the spinner.Then the rpm should try and stay the same. The catch of course is that your rpm set has to be less than what the motor can turn with that prop on the bench at wide open throttle. Are you sure it is setup that way? If not, then as the battery drops, then since the governor is already maxed out, all it can do is slow down.

You might need to play with the high and low aspect of the governor. At least with the Castle Creation Phoenix, I need to use high with a 12 magnet motor (like the Scorpion or AXI), while with a 10 magnet motor like the stock Brodak Super Clown, I had to use low mode to get the rpm in the 9k range.

With regards to motor timing, I "think" it means when exactly the ESC does it commutation "thing". So hard timing means (again I think) that the ESC waits later to switch to a new armature leg. By later I mean as the energized tooth of the armature approaches one of the permanent magnets, the torque actually drops (since it goes as the sine of the angle) and at the same time the back EMF is also dropping (also as the sine of the angle). This means the current from your battery is really peaking for "not much" torque. However if you want power and can afford the bill (lower efficiency), you may want to go this way. Otherwise if you prefer to give up a little power to have a higher efficiency, then I think you should choose a softer timing. This will switch the energized tooth off a little earlier and go to one of the other two legs (more or less), where the tooth is at a larger angle to the magnet. Basically I think I just choose "default which is somewhere between the two.

Dean Pappas · « **Reply #23 on:** February 25, 2008, 01:24:09 PM »

Quote from: Mike Anderson on February 25, 2008, 09:00:54 AM

Archie-

I'm still trying to figure out this Governor stuff - I got a "HQControl" ESC - 40 Amp - from the want-ads
at RCGroups - it comes with a little blue box programming unit. Down the list of options are -
Governor - and you can choose Off, Lo or Hi. But I'm not able to see any results of the Governor setting
when I run a motor - RPM still drops off as the battery voltage sags, Loading the motor a bit while its
running by adding some drag with my thumb on the bell housing (trying to simulate going into a maneuver)
doesn't seem to do anything.

My question is, have you got the Turnigy ESC Governor function to work the way you want it to - or
at least the way you think it should work - and how do you test it ? What should a person be seeing?

Mike A

Hi Mike,
Heli or governor mode (two names generally used for the same thing) hold a constyant RPM, based on the control pulse width that would normally come from an RC receiver. Where 1000 micro-seconds is stopped and close to 2000 micro-seconds is wide open throttle in normal mode, the governor mode will be stopped at 1000 uS, and will start up at something like 1100 or 1200, and immediately go to some low RPM (really pole passing frequency) and further pulse width increases will lead to increases in the commanded RPM.

How do you test it?
1) Start with a prop that is about the size you want, and with the ESC in regular throttle mode, find the WOT RPM. Never expect more than this.
2) Put the ESC in governor mode, and strat up with low throttle /pulse widths. Use a servo controller or a radio for this step.
Set the RPM to maybe 80-% of that found in step #1.
3) Shut down, and put a small prop on the motor. Restart, and go back to the same throttle or pulse width setting and check to see if the same RPM results. It should.

With the small prop, you can graph out the RPM versus pulse width for your motor (number of poles) and as long as you do not put too much prop on the motor, that will be the RPM you get. It will compensate for changes in battery voltage and maneuvering load, as long as the prop could turn faster on the existing voltage.

I hope that helps.
Dean Pappas

P.S. Hard timing is more advanced, and soft timing is more retarded. The advance is there to make up for the time it takes for the current to ramp-up in the inductive windings. Inrunners and higher Kv outrunners typically have less inductance, and do well with soft timing.

Mike Anderson · « **Reply #24 on:** February 25, 2008, 02:02:21 PM »

Thanks for the replies, Archie and Dean --

I'll try that method of testing when I get back into the shop.

I understand what timing advance is -- going back 10-12 years and rewinding/reworking brushed
motors for sailplanes. You could change the timing of the commutation or switching points
by rotating the brush-holders.

But my experience (limited) is that none of the ESC settings for timing advance SEEM to have
any influence on actual RPM or Current draw for any particular prop. Again, though, this is all
from running motors on a bench, not an actual airplane at the flying field. And what flying I
have done has been with throttled motors (Navy Carrier event) not stunt motors running
at more or less constant RPM. So, when Archie said that the controllers actually exhibited
some results with respect to the "Timing Advance" setting, I'm wondering if he actually saw
an RPM increase/decrease as a result of that setting change?

Thanks again --

Mike A

Dean Pappas · « **Reply #25 on:** February 25, 2008, 08:35:36 PM »

Hi Mike,
My Castles sure seem to increase in current, and a few RPM when I use more advance!
This has been true at 400W and at 2800. 10S and 85 amps ... you've got to love it.

later,
Dean

Mike Anderson · « **Reply #26 on:** February 26, 2008, 08:16:55 AM »

I guess I just have to break down and get a real ESC - and quit trying to get
the cheapo ones to do what they can't --

You can't make a silk purse out of a sow's ear (hey, I'm from Iowa. I only
KNOW farm sayings.)

I did try the test sequence you outlined -- I set up the motor with an 11-4.5
and a 3 cell battery - checked for max RPM, set the timer for 1.8 msec and read
5700 RPM. Changed to a smaller prop (8-4 APC E) - In "Gov-H" it read about
6300 RPM and didn't seem to regulate. In "Gov-L" it read about 6000 RPM and
also didn't seem to regulate. I have the distinct impression that the only thing
this ESC can do is store the name of a setting, not actually do what the setting
says. I will try once more tonight, with a different motor/battery and higher
power levels, but I don't expect much more success.

That is really OK, as I'm not ready for any kind of high precision control anyway-
I'm just trying to see what the equipment I have will do, so when I am ready
for more features, I'll know what to obtain. I'll still be very interested to know
if Archies "Turnigy" ESC's do work in the outlined fashion.

Mike A

Archie Adamisin · « **Reply #27 on:** February 27, 2008, 05:51:17 AM »

Mike,

I have (3) different controllers of which the Phoenix is the best for it's governor reactivity. The Kontronik 3SL70-6-18 is very reactive, yet is not as quick. The Turnigy seems to be reactive, but it doesn't work like either of the other(2). The (2) biggest advantages of the Turnigy over the Kontronik and Phoenix is the ability to arm the brake while in governor mode & the price. I have about 25 flights in using electric power. It is a pain to land an airplane with a freewheeling propeller to say the least especially in the wind.

Even with the great reactive time of the Phoenix controller, I have found that your aircraft's performance is more dependent on prop choice. Though others will disagree, more than 5.5" pitch really makes the any type of governing lethargic. I have used the 10 x 5 APC E prop with the greatest amount of success of all the props out there. I plan to use the 11 x 5.5 on my full blown stunter and want to experiment with 3 & more blades to give more effective disc area. The goal is to be less dependent on the governor and more dependant on the prop. No matter how much power the motor develops, the prop is the medium which power is delivered & braking applied.

I expect to find that there is very little difference in the feel at the handle between the (3) controllers I have. I have flown (3) completely different motor/controller setups in the same airframe and when set to the same lap speed, there is little to no difference between them. The biggest bonus would be that no broken props on landings with the Turnigy!!

For 1/2 A's, I would worry less about governors and more about getting the power required to fly. I have flown some of Todd Lee's 1/2 A stunters and with the TD 049 screeming on a 5.7 x 3 prop turning in 4-4.5 sec laps was the best. 1/2 A sized airframes will need quicker lap times to give the speed required to perform a stunt pattern. This is why I suggested using the in-runner because they are better suited for this task. You could buy a complete setup including battery from Hobby City cheaper than it would cost you to get a Cox TD 049 these days.

I wouldn't break down and get the expensive ESC yet. I have one and right now am not sold on it. We'll see how it goes once I get the Turnigy in the air and see how much better or worse it is or if there is even any difference. I expect it to be slightly different, but not to the degree that it would be a show stopper.

Archie Adamisin
Muncie, Indiana

Mike Anderson · « **Reply #28 on:** February 27, 2008, 07:48:36 AM »

Hi Archie-

Hey, great info and write-up. I'd pretty much decided to worry more about
getting some of the hardware that I already have into the air than getting
more hardware, just yet.

I have a tendency to buy things to try, rather than try and see what to
buy (wow, how poetic).

So, will you be at the Jim Renkar's 1/2A bash, or at Sig? Or perhaps even
at the Des Moines contest [ which I CD ..

] We have a couple of guys
who come from Indiana, usually.

Thanks to all who answered in this thread, too. Learned a lot.

Mike A

Archie Adamisin · « **Reply #29 on:** February 27, 2008, 08:13:20 AM »

Mike,

I will have a very limited contest schedule this year, but am planning on going to Brodak and also FCM. I'll probably take a day off and go to the nats to visit with old friends if I can since it's so close.

When is Jim Renkar's 1/2 A bash? I'd enjoy that.

Archie Adamisin
Muncie, Indiana

Mike Anderson · « **Reply #30 on:** February 27, 2008, 08:33:24 AM »

Sometime in September -- Alan may chime in here, as he is the
one who brought it up originally.

Dean Pappas · « **Reply #31 on:** February 27, 2008, 09:38:49 AM »

Hi Guys,

Archie,
the tighter governor will really matter in runway wind. Whip-up in the wind is the big difference between loose and tight governors.
For Sport, sure: anything will do for just keeping the lap times relatively constant.

Mike,
You probably have to teduce the pulse width to something much shorter than 1.8 mS to get regulation.
Try maybe 1.3 or so. You may even need this combined with the low range. You need to see less than the 5700 RPM you got at WOT with the 11 X 4.5, otherwise the governor is set for faster than the motor can achieve. On an AXI 28XX motor, 1.3 mS equals ~9300 RPM on the GOV-HI range. GOV-LO range tops out at 9,000 RPM, even with 1.9 mS from the timer. Your motor's pole count will change this, possibly.

Dean

Archie Adamisin · « **Reply #32 on:** February 27, 2008, 09:54:18 AM »

Dean,

I completely agree to a point about wind whip up. The governor reactivity does make a difference, but I believe that is very dependant on the pitch of the prop. Even if you govern say the targeted +/- 200 rpm, 5 pitch has a less effect on rpm change than 7 pitch. I have flown both and believe me that even though the 7 pitch used significantly less power, it whipped up terribly. Please see the attached Eagle tree plot. According to the Eagle tree, all was very good. At the handle, it wasn't!!!

I am not one to say that a governor is useless, but I will say it's a combination of prop choice and governor that will control speed. No matter how effective the governor is, pitch will determine the flight speed. The more effective you can use the prop to control speed, the less effective the governor has to be.

Speaking of which, has there been any news from the Castle camp on the addition of brake parameters while in governor mode? I have gotten no answers but after the new year and well, we are almost to March now.

Archie Adamisin
Muncie, Indiana

Dean Pappas · « **Reply #33 on:** February 27, 2008, 10:50:52 AM »

Hi Arch,
It's really the pitch versus diameter ratio. If you could change motors to one with a Kv one-half of the original and run twice the pitch, in inches, and enough additional diameter to absorb the same wattage, then the braking would actually get better.

But ... As long as we are talking about keeping the diameter constant, or very close to it, and the same motor Kv, then less pitch offers better braking. That was the case you were talking about, right?

There: I added complexity. I feel better!

take care,
Dean

Dean Pappas · « **Reply #34 on:** February 27, 2008, 10:59:53 AM »

Hey archie,
Let me guess ... the airplane shown in the data-logger file weighs between 40 and 42 ounces.
Huh? Based on 0.71 Watt-Houirs per ounce to fly the schedule.
I'm looking for more data points to confirm this 0.71 figure.
Dean

Kim Doherty · « **Reply #35 on:** February 27, 2008, 12:02:57 PM »

Quote from: Archie Adamisin on February 27, 2008, 09:54:18 AM

Dean,

I completely agree to a point about wind whip up. The governor reactivity does make a difference, but I believe that is very dependant on the pitch of the prop. Even if you govern say the targeted +/- 200 rpm, 5 pitch has a less effect on rpm change than 7 pitch. I have flown both and believe me that even though the 7 pitch used significantly less power, it whipped up terribly. Please see the attached Eagle tree plot. According to the Eagle tree, all was very good. At the handle, it wasn't!!!

I am not one to say that a governor is useless, but I will say it's a combination of prop choice and governor that will control speed. No matter how effective the governor is, pitch will determine the flight speed. The more effective you can use the prop to control speed, the less effective the governor has to be.

Speaking of which, has there been any news from the Castle camp on the addition of brake parameters while in governor mode? I have gotten no answers but after the new year and well, we are almost to March now.

Archie Adamisin
Muncie, Indiana

Hi Archie,

While I fully appreciate that cost is very much a factor in any decision to use one piece of equipment over another, it needs to be understood that inexpensive motors, esc's and batteries do not perform the same as higher end equipment. Not just a little bit of difference. A lot!!

As I have mentioned before, you need to determine what your goal is prior to putting a setup together. If you want something that is inexpensive and disposable then it is likely that you will have to give something up in return for the lowered cost. Picking cheaper components and then saying that they do not perform the way you thought they should is like going to McDonalds and being miffed that the burger was not cooked to your specification.

Is money the solution to all of the issues affecting electric flyers? Clearly not but you will save yourself a world of pain in purchasing and using the better components.

On the subject of GOVERNOR MODE, there is more to this than meets the eye. Although it would seem a simple enough task to regulate the rpm, how it is achieved and to what degree of accuracy is a whole other matter. The algorithms for rpm control are as secret as the recipe for Coca Cola. There is a BIG difference between the governing abilities of a Schulze 18.46k - F2B esc and an inexpensive knock off from China. Therefore ascribing the governing characteristics of a cheap esc in governor mode to all esc's is not correct. Just for comparison, EVERY aspect of the governor mode algorithm in the Schulze has been optimized for control line. The esc has <20 rpm resolution. (try that on a cheapie esc!) The changes implemented in this esc go far beyond what you can achieve even by tweaking all of the tunable parameters in the CC esc. You get what you pay for.

The only reason people use lower pitch props is because the engines they are running make their power at a higher rpm. Larger diameter, higher pitch props are simply more efficient (including braking). Since it takes more torque to turn a larger prop and since electric outrunner motors make LOTS of torque, I think you will find the best solution in that direction.

If your plane is winding up in the wind or if you are experiencing +-200 rpm swings during flight your motor is not being governed adequately.

In no way am I beating up on your choices of equipment. There is a place for all types and quality of components. I think it is important though to compare apples to apples and esc's to esc's.

Kim.

Archie Adamisin · « **Reply #36 on:** February 27, 2008, 12:32:48 PM »

Kim,

Great to hear from you. Perhaps my posts have been misunderstood. In no way am I suggesting that cheaper equipment would outperform better equipment. I am saying that the governor is a tool, not the saving grace. The Castle is not optimized for CL flying in it's current program beta. It is best if used to fly rc airplanes & heli's in it's current configuration. The governor works great to maintain whatever throttle setting I have chosen, but even in the instruction manual it suggests to heli users that if you don't like the head speed, change motor Kv or gear ratio which implies that the governor works best at full throttle. I have not had the opportunity to try the Jeti or Schulze controllers but have heard great things about them.

My intentions here are to draw on and share my experiences with the ECL and what I learned when flying F5D for the past several years. I am glad to see so many people in this forum that also share what they have learned. My experience so far has shown that high pitch regardless of (pitch to diameter ratio) isn't the way to go no matter how well your governor works. I also present that if propped correctly, the governor's ability to control speed can be greatly increased.

On price point, my 3SL70-6-18's cost me $300 a piece in 2000. I own (4). I have Kontronik motors, Hacker motors, Astroflight motors, Rim-Fire motors, Tower Pro motors, and now Turnigy motors. The price difference in all these motors is significant, however the quality of the cheaper turnigy motors is very close to these more expensive motors. I think there is a direct apples to apples comparison to show perhaps a performance per dollar. When reading the Amped up column, I feel many who would want to try ECL, would be turned away from the cost of it when they see $250 battery packs, $150 ESC's, and $100 motors. It has been my goal to make it more feasible for the average modeler and even those who wish to compete.

Archie Adamisin
Muncie, Indiana

Archie Adamisin · « **Reply #37 on:** February 27, 2008, 12:34:32 PM »

Dean,

The 10 x 7 was flown on the same 48 oz Oriental with the 35-36-1200 and 3s 4000's.

Archie Adamisin
Muncie, Indiana

Archie Adamisin · « **Reply #38 on:** February 27, 2008, 12:42:05 PM »

Quote from: Dean Pappas on February 27, 2008, 10:50:52 AM

Hi Arch,
It's really the pitch versus diameter ratio. If you could change motors to one with a Kv one-half of the original and run twice the pitch, in inches, and enough additional diameter to absorb the same wattage, then the braking would actually get better.

But ... As long as we are talking about keeping the diameter constant, or very close to it, and the same motor Kv, then less pitch offers better braking. That was the case you were talking about, right?

There: I added complexity. I feel better!

take care,
Dean

Dean,

Well, what I would like to try is to make a prop that had say 6.5 pitch at the hub/spinner and 4 pitch at the tip. The lap speed would then be determined using the average pitch and the wattage needed would be reduced to maintain proper lap speed. The diameter would be increased if added thrust was needed to overcome the drag of the airframe. Thrust gets you there, and pitch determine speed. If you don't have the thrust, you can't get there.

Having the governor is a great tool, but in my experience it can't be oversold that no matter what prop you use the governor will control the airspeed. Some of the comments I have seen heard when talking about governor mode is that it will maintain constant speed and thats not the case. The combination of prop and governor response is the ticket. Throw in another factor, airframe drag too.

Archie Adamisin
Muncie, Indiana

Mike Anderson · « **Reply #39 on:** February 27, 2008, 12:57:42 PM »

Wow - talk about a thread that has shifted direction. I guess I'm partly
to blame for bringing up governor mode in a what started out as trying
to get a 6 inch prop up to speed for a 1/2A stunt event.

In any case, thanks again to all who have chimed in. I've learned much
in the course of it. To expand on Dean's point about the ESC governor
that doesn't, so I may need to get a motor with a higher Kv if I'm only
running 3 cells ? I'll try an AXI 2826-8 since I have one currently
unmounted on anything else. The motor I've been trying to use is
probably in the low to mid 700's for Kv (I don't know for sure because
I rewound it last fall and did not try to duplicate the wind it had on it).

Then at least we should be up in a more realistic RPM range on 3 cells.

Thanks again.

Mike@

Archie Adamisin · « **Reply #40 on:** February 27, 2008, 02:45:29 PM »

Alan,

Boy have we blown away the point of your trials with 1/2 A electrics. I look forward to your findings with your hand wound motors. I have some projects to complete before, but I would really like to put together a 1/2 A electric stunter with the in-runner we discussed and see how it goes. Think of all the fun with 1/2 A's without all the noise, hard starting, blown glow plugs, and the mess after.

Let us know when you get a chance to get in the air.

Archie Adamisin

Muncie, Indiana

bfrog · « **Reply #41 on:** March 02, 2008, 11:25:38 PM »

Back to the basic 1/2 A idea.

I received some motors/ESC's, a battery and a cheap charger from United Hobbies. I want to see if some of the less expensive gear would work for small planes. I was just going to hook them up and run them on the bench but I wanted to get better data than a simple test. So I built up this test set-up that should work for any number of motors. I use a watt meter and a tach besides reading the thrust off of the scale. The servo driver is a small pulse generator that I got from Will Hubin, it works great. The wood setup is not perfect, no ball bearings in the arm and with some motors it will be a little off balance (adjusted out with tare weight on the scale). It should at least provide consistent data for the motors I put on it. I tried to make it so I could put different mounting heads on it for different styled motors. Just got it up and running and have only one data point.

TowerPro (United Hobbies) BM2408-21T / 18A BEC / GWS 9X5 prop (the motor, ESC and a prop are $14.49 plus shipping)

3 cells with the 9X5 prop throttled to 13.5 Amps gives about 130 watts, 7500 RPM, roughly 20 oz of thrust

The motor seemed pretty warm, almost hot at this setting. Good thrust though.

In the coming week or so I plan to run other props and get a range of data. I'll post more data as I get it.

Mike Anderson · « **Reply #42 on:** March 03, 2008, 07:53:21 AM »

Quote from: bfrog on March 02, 2008, 11:25:38 PM

Back to the basic 1/2 A idea.
........

TowerPro (United Hobbies) BM2408-21T / 18A BEC / GWS 9X5 prop (the motor, ESC and a prop are $14.49 plus shipping)

3 cells with the 9X5 prop throttled to 13.5 Amps gives about 130 watts, 7500 RPM, roughly 20 oz of thrust

The motor seemed pretty warm, almost hot at this setting. Good thrust though.

In the coming week or so I plan to run other props and get a range of data. I'll post more data as I get it.

Oohh - that's a bit of a heavy load for that little guy. It's quoted spec's are similar enough to the Suppo that I showed in the 1/2E Skyray pix that I believe they are probably the same motor. In any case, there is an on-line set of points and runs for mine (B2408-14) at LightFlightRC.com.

(Oops - there is no complete review of this motor on their site - there is only this info:
Here's our quick results so you can get an idea:
Recommended:
APC 8 X 3.8 SF draws about 11A on a 3S pack
APC 10 X 4.7 draws about 9.5A on a 2S pack
APC 11 X 4.7 draws about 10.5A on a 2S pack )

You can see that your 9-5 @13A+ would probably fit right on this table.

The specs say max of 13.0 amps for 30 sec. I plan on two cells with an 8-3 or 7-6 prop and the amp draw should be about 10 amps on the ground. Your 3-cell setup will probably be OK in the air.

(My batteries are still "In transit" .... maybe someday.)

Mike@

bfrog · « **Reply #43 on:** March 03, 2008, 09:07:09 AM »

Mike,

Yes, I thought that was a little high. When I first turned it on with the 10X4.7 it ran up to over 20 amps!!!! I had to adjust the throttle to keep it at 13. (by the way the pulse driver I got from Will works really well, would be nice to have the one that displays pulse width, he's working on that too) The specs that United Hobbies shows at 10 V, 13 amps with a 10X4.7. I am going to try some smaller props and also a 2 cell setup. I have a 3 cell pack that has one bad cell so I'll have to do some surgery and make it a 2. Haven't taken apart lipo packs before. Is there anything I need to watch out for?

I'm a little confused here though. Shouldn't the lower voltage require higher current? Why should the 2 cell pack draw less? Does the lower voltage just limit total power? I would be very happy with about 10 amps at 7.4 volts. 70 to 80 watts is about perfect for 1/2A sized planes.

United has 2 cell 1000 mah batteries rated 15C for $9. That would make the whole package of motor, ESC, battery cost about $25. Still need a timer, use one of Will's for $16 and your off and running. Throw in one of their cheap balancing chargers like the one I just got from them for $25 and you have all you need for about $66. This puts it at or lower cost than a glow 1/2A power package and you have "fuel" for a lot of flights already in the batteries. At that price electric has a lot of advantages.

One last thing, the "cheap" charger can charge 2,3 or 4 cells. I charges off the balancing plug so it charges each cell seperately. It has 1/2, 1, 1.5, and 2 A charge current settings. There are led's to show status of each cell, charging or fully charged. For the price it seems to work very well. Should be perfect for a starter setup.

Bob

Mike Anderson · « **Reply #44 on:** March 03, 2008, 10:17:54 AM »

Quote from: bfrog on March 03, 2008, 09:07:09 AM

Mike,

Yes, I thought that was a little high. When I first turned it on with the 10X4.7 it ran up to over 20 amps!!!! I had to adjust the throttle to keep it at 13. (by the way the pulse driver I got from Will works really well, would be nice to have the one that displays pulse width, he's working on that too) The specs that United Hobbies shows at 10 V, 13 amps with a 10X4.7. I am going to try some smaller props and also a 2 cell setup. I have a 3 cell pack that has one bad cell so I'll have to do some surgery and make it a 2. Haven't taken apart lipo packs before. Is there anything I need to watch out for?

I'm a little confused here though. Shouldn't the lower voltage require higher current? Why should the 2 cell pack draw less? Does the lower voltage just limit total power? I would be very happy with about 10 amps at 7.4 volts. 70 to 80 watts is about perfect for 1/2A sized planes.

United has 2 cell 1000 mah batteries rated 15C for $9. That would make the whole package of motor, ESC, battery cost about $25. Still need a timer, use one of Will's for $16 and your off and running. Throw in one of their cheap balancing chargers like the one I just got from them for $25 and you have all you need for about $66. This puts it at or lower cost than a glow 1/2A power package and you have "fuel" for a lot of flights already in the batteries. At that price electric has a lot of advantages.

One last thing, the "cheap" charger can charge 2,3 or 4 cells. I charges off the balancing plug so it charges each cell seperately. It has 1/2, 1, 1.5, and 2 A charge current settings. There are led's to show status of each cell, charging or fully charged. For the price it seems to work very well. Should be perfect for a starter setup.

Bob

OK - one at a time:

LiPo surgery - Be VERY careful that any battery terminal can not touch any other battery terminal except the one you are soldering it to or un-soldering it from. The main thing to watch here is terminals that have wires on them - the wires tend to flail about while you are maneuvering the pack and your iron - etc. Put tape over any bare wires as soon as you unsolder them. If a bare end touches a terminal of another cell, you may get sparks and you COULD get welding, which is real bad because lots of current flows while you are trying to figure out how to disconnect the wire. Also, remember that you probably need to change the balancing connector - either to a different one altogether or rewire it -- depends on your charger. If you are changing it, it's probably easiest to just splice the new one in one wire at a time. Don't forget the heat shrink over the joint. Just remember that even on the balancing plug, if you have a bare wire end, the other end goes to a battery terminal. Also, just a personal observation, is wear eye-protection especially when soldering large joints with large irons. Somewhere I've got a pair of safety glasses with a big SPLAT of solder right in the middle of one lens from trying to solder a big wire into a big pin with a big iron. If you have any specific questions, e-mail me. I'm happy to help, but don't want to drag this thread off in a new direction.

On the voltage question - Current is a result of voltage (among other things). So if you lower the voltage, but change nothing else, you lower the current. Current is also a function of load (diameter and pitch, primarily). If your current is too high, you can decrease the load, and keep the same battery. Heat is a function of current (squared, actually). Your question was "Shouldn't the lower voltage require higher current?" -- the answer is "Depends". If you want to keep the power level the same, then yes it requires higher current. But in your case, the motor was hot so the power was already too high. You can lower the input power by decreasing the voltage and/or the load. You also have to factor in the weight of the additional cells or the additional capacity (1000 mah cells weigh more than 800's, etc.) Lot's of numbers to play with . .

On the "United Hobby" (remember - it's HobbyCity now

) battery prices - just keep in mind that with shipping, just about any battery will add about $5.00 to the total - so 3 $13.00 batteries ended up costing me ~$18.00 @ - still not bad, but you have to also know what is available elsewhere. My "DealExtreme.Com" batteries are 900 mah, 15C (2-cell). They are under $8 per battery and shipping is free. So if only half of them are any good, it's still cheaper than the same battery from HobbyCity. Problem is, they only have that one size (up to now). Also, they are prone to be unable to keep them in stock also.

Mike

Dean Pappas · « **Reply #45 on:** March 03, 2008, 01:54:44 PM »

Hello All,
Hi Kim, Boy am I glad you weighed in!

You're absolutely right about the differences in governors.
As you know, I've been pushing the Castle because it had the fastest and tightest loop of the ESCs we tested, as it was: without any further mods from the factory. Of course it does not allow the brake to work in governor mode ... some excuse about breaking heli main shafts if the brake ever engages. By the way, I don't buy that logic, because autorotations would still require an overrunning clutch. Maybe the small cheap helis don't have auto-clutches. I'll go check that.

Anyway, just a few days ago at the WRAMs show in New York, I asked the marketting guy from Castle yet again, when we could expect to see the Stunt governor plus brake. It isn't coming anytime soon. I don't like being shined-on. I had a face to face with Mr Castle himself, and I expected it by sometime close to now. Now I have to get a Schultze to test.

Erik Janssen, that is Bruno from Holland's buddy, did a beautiful test that involved applying a step change in load (both rising and falling) by partially stalling and unstalling a test prop with a hinged board and carefully placed stops. After trying to see whether could help Erik get this published, I think I shall just urge him to post it here in a separate thread called "governor characteristics" or something similar. It was a beautiful piece of work, and if it can be widened by testing some loaner ESCs, then so be it.

take care, Friends
Dean Pappas

Alan Hahn · « **Reply #46 on:** March 03, 2008, 02:35:06 PM »

Yea, I go away a week to Switzerland (to CERN, http://public.web.cern.ch/Public/Welcome.html, where the Internet was born

no less!) and look what happens!

I wasn't even planning to run no stinkin' governor on my 1/2A.

About governors---I have no big problem with my CC, they seem to do a pretty good job as indicated by my Eagle Tree data logger under actual flying conditions. I can believe there are some manufacturer's whose governors don't work. In any case, loss of airspeed is a lot more gradual than anything I see in the rpm data. I think the issue is getting a good prop which will increase thrust fast as airspeed begins to drop as the climb commences (or vice versa during a dive). I do agree that a brake would be nice since the windmilling prop really slows the plane down in a hurry when the motor times out.

And about good equipment---I think in the long run it pays off. The fine line is between "good enuf" and overkill. As one who does High Energy Physics Experiments, the key thing to remember is that "better is the enemy of good!"

ps, the weather in Geneva Switzerland was fantastic, however after on nice day on Sunday here in Chicago (didn't get out

), we are back to winter.

Dean Pappas · « **Reply #47 on:** March 04, 2008, 09:32:25 PM »

Hi Archie,
I apologize, as I never responded to your thoughts on prop pitch.
The short answer is: try it and tell me!
The book (and the danger with the book analysis is that simplifying assumptions must be made) is this:
You want a prop that, at a constant RPM, increases load torque as rapidly as possible with a single MPH of decreased airspeed.
This is also the same thing as saying that it requires more Watts to increase a given number of RPM, assuming the plane is flying at a constant airspeed.
That will force more Watts to be summoned by the governor loop when the airspeed starts to drop in a corner.

This is not the same as desired in an IC system!

Does non-helical pitch flatten the torque versus airspeed curve? I think so. Go prove me wrong: I love a good experiment. The best propo Hunt has put on his Genesis is an APC 12-6 E prop. It haswide blades, helical pitch, and thin airfoils.

When it warms up, I'll try too!
Let's experiment together (virtually that is!) when it warms up.

Dean

Igor Burger · « **Reply #48 on:** March 04, 2008, 11:47:10 PM »

>>>The best propo Hunt has put on his Genesis is an APC 12-6 E prop.<<<

and what about 3bl prop like this (11x5.5):

Archie Adamisin · « **Reply #49 on:** March 05, 2008, 10:26:41 AM »

Wow, it's awful risky to run a 9 x 5 on a Tower-pro 2408-21T with 3 cells. Try a 6 x 3 or a 6 x 4 on 3 1000's and you will get a bunch of RPM similar to what I got on the Hextronic 2080 Kv inrunner. This Tower pro motor I use in our clubs WW2 R/C foamy combat with (2) cells and 9 x 7 props. It is a stout little motor!!

Archie Adamisin

Muncie, Indiana

Author Topic: 1/2 A Electric--first try (Read 10818 times)

Alan Hahn

Alan Hahn

Alan Hahn

Alan Hahn

Alan Hahn

Alan Hahn

Alan Hahn

Alan Hahn

Kim Doherty

Alan Hahn