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-   -   Great Planes 81" Yak 54 E power system? (https://www.wattflyer.com/forums/showthread.php?t=59786)

grhm 01-16-2011 07:30 AM

Great Planes 81" Yak 54 E power system?
 
I just got a Great Planes 81" Yak 54 from a friend. It calls for a 1.60 glow or a 32-43CC gas motor. I was going to put a G38 gas engine on it, but before I do I thought about an electric setup for it. The specs on it says RTF is about 12.5lb -15.25lb weight. I don't really know much about electrics. I do know that I WONT be doing hard 3D, just mild aerobatics.
What would be a good setup for this? And I will want to use good quality components.

constantCrash 01-16-2011 01:51 PM

Hobby King Turnigy Power 160; http://hobbyking.com/hobbyking/store...dProduct=14408

Turnigy 120A HV speed controller: http://hobbyking.com/hobbyking/store...idProduct=8921

should be s good place to start

kyleservicetech 01-16-2011 03:23 PM


Originally Posted by grhm (Post 778045)
I just got a Great Planes 81" Yak 54 from a friend. It calls for a 1.60 glow or a 32-43CC gas motor. I was going to put a G38 gas engine on it, but before I do I thought about an electric setup for it. The specs on it says RTF is about 12.5lb -15.25lb weight. I don't really know much about electrics. I do know that I WONT be doing hard 3D, just mild aerobatics.
What would be a good setup for this? And I will want to use good quality components.

I've finished a 78 inch wingspan, 1200 square inch wing for a Goldberg Extra 330 ARF. Power is a Hacker A60-16M motor, Castle Creations 80 Amp ICE HV ESC, Castle Creations uBEC, 12S2P (12 series, 2 parallel) 2300 Mah (milliampere hour) A123 cells.

This setup turns the prop at 6700 RPM, for about 65 Amps and 2400 Watts. The total model weight is 16.9 pounds, for a power ratio of 2400 watts divided by 16.9 pounds = 142 watts per pound. This Hacker motor has slightly more horsepower than a 30 cc gasoline model airplane engine.

Perhaps 1 - 1 1/2 pounds could have been saved by going to Lipos, but I can charge these batteries while still in the plane. Those A123 cells have zero fire hazard.

Agreed, Hacker motors are expensive, but I've got 7 of them, ranging from an A30, A40, A50 and this A60 class motors. Every one of them performed exactly per specifications. And after three years and several hundred flights each, all have been flawless.

To help in your decision, check out www.motocalc.com a software program for electric models, free for 30 days, then its $39.00 and worth every penny.

Check out my thread on medium size electric models to get a little idea of what's what's involved with them.

Thread on 70 size glow engine conversion to electric
http://www.wattflyer.com/forums/showthread.php?t=45222

Good Luck!

grhm 01-16-2011 06:15 PM

I would rather stay away from the King Hobby stuff. I would rather pay more now than buy over and over again.


Originally Posted by kyleservicetech (Post 778086)
I've finished a 78 inch wingspan, 1200 square inch wing for a Goldberg Extra 330 ARF. Power is a Hacker A60-16M motor, Castle Creations 80 Amp ICE HV ESC, Castle Creations uBEC, 12S2P (12 series, 2 parallel) 2300 Mah (milliampere hour) A123 cells.

This setup turns the prop at 6700 RPM, for about 65 Amps and 2400 Watts. The total model weight is 16.9 pounds, for a power ratio of 2400 watts divided by 16.9 pounds = 142 watts per pound. This Hacker motor has slightly more horsepower than a 30 cc gasoline model airplane engine.

But I think I need something that would be about the same a say a 40cc gas motor. Although, I am hoping to get my total weight to about 15lbs.

Graham

kyleservicetech 01-16-2011 09:27 PM


Originally Posted by grhm (Post 778114)
I would rather stay away from the King Hobby stuff. I would rather pay more now than buy over and over again.



But I think I need something that would be about the same a say a 40cc gas motor. Although, I am hoping to get my total weight to about 15lbs.

Graham

Check out the Hacker A60-16L motor on 12S Lipos. That will exceed a 40 cc gasser. Hacker indicates this motor will turn a 22X10 APC-E prop at about 6200 RPM, pulling some 2500 watts. Unfortunately, trying to hit a total weight of 15 pounds will not be easy, unless your model is really light.

Check out my thread on this subject:
http://www.wattflyer.com/forums/showthread.php?t=58035

The info on the Hacker in this thread is a little out of date. I checked my Hacker A60-16M motor, it turns a 19x12 APC-E wide blade prop at 6700 RPM on those 12S2P A123 cells.

Or, if you really want sticker shock, checkout the A80-8 motor, plus its required batteries and ESC. That motor will turn an 26 inch prop at some 6000 RPM, pulling some 6000 watts.

grhm 01-16-2011 10:38 PM

No can do on a 22" prop. I don't have the clearance with a safe margin. Biggest I probably could go and feel safe is a 20". I really wanted to Limit it to 10S setup.

grhm 01-16-2011 10:43 PM

One other thing. Batteries. What kind of C rating should I be looking for? 30C, 40C ect.
Thanks

kyleservicetech 01-17-2011 03:20 AM


Originally Posted by grhm (Post 778161)
One other thing. Batteries. What kind of C rating should I be looking for? 30C, 40C ect.
Thanks

Usually, (again, usually!) the higher the C rating, the better quality the battery. Unless the mfg is lying about their batteries performance. Many wattflyer readers have found that actually running their battery at its maximum "C" rating results in shorter battery life. Sometimes much shorter. A local electric flyer found that his three batteries lasted five flights each at their maximum rating!

Something else on that "C" rating. Take 60 minutes, divide 60 by the "C" rating you are using, that is the flight time. Example, 60 minutes divided by 40C equals 1.5 minutes at full power. That is true, regardless of the ampere hour capacity of that battery. Worst of it is, at 1.5 minutes discharge time, the batteries internal heat has a problem getting to the outside of the battery quickly, so the batteries internal temperature can be higher than what the batteries exterior shows. And, various threads have indicated that the maximum safe internal temperature of these lithium based batteries is about 140 degrees F.

I don't run my A123 cells much over 10-15 degrees above ambient temperature, and never past about 60 or 70% of battery ampere hours on a typical flight. And after three years and 200 flights on each of my 6S2P A123 packs, they have the same performance as when they were brand new.

Larry3215 01-17-2011 06:45 AM

You might consider the hacker A60-16M if your going to run on 10S. You should see around 2000 watts with a 20x10 prop and good packs.

Id suggest 5000 mahr packs from Hyperion, The CX packs would do fine. They are 25C rated packs so you will be fine. The quality is excellent and they actually get better with use. You should easily get a few hundred cycles from the packs if you dont abuse them.

They should give you nice long flights if your just doing sport flying and probably in the 8-10 minute range even if your pushing them hard now and then.

Id also highly recommend a Castle ICE HV controller. An ICE HV 60 or 80 would do fine with the above setup.

grhm 01-17-2011 07:18 AM


Originally Posted by Larry3215 (Post 778247)
You might consider the hacker A60-16M if your going to run on 10S. You should see around 2000 watts with a 20x10 prop and good packs.

That is the exact system I am looking to get.
Would there be any benefits running a 12S with the added weight?

Larry3215 01-17-2011 08:04 AM

Im a big fan of building as 'lite' as possible. If you add in that you only want to do mild aerobatics, then I see no reason to add the weight.

You could probably even get by with smaller cells than the 5000's and still get reasonable flight times.

However, I would wait to order any packs until you have the model mostly built and the motor mounted. Then you will see what you need in terms of weight in the packs to get a good CG.

No point in adding lead when you could use battery instead.

On the other hand - on all my large models I go with the highest voltage I can and choose motors, gear boxes etc to maximize power and minimize weight.
Higher voltage allows you to get higher power levels at lower amp levels.

For example, to get 2000 watts on 10S means you have to draw in the 57 amp range. To get the same 2000 watts on 12S means your max amp draw goes down to 47 amps.

That means you can either pull more amps on a 12S setup for the same flight time - or have the same power and fly longer and have all your components run cooler.

Heating is a function of I^2*R so heating losses go up (or down) as the square of the current. So yopu can generally get a slightly more efficient system by going with higher voltage.

On my 86" Yak I used a Neu 1515 motor and ran it on 12S with a 22" prop at about 3200 watts peak. My model weighed right at 18 pounds all up.

I used the same power system on a GP Ultimate that also ended up about 16 pounds.

By the way, dont be surprised if your model ends up a few pounds heavier than advertised.

flyer88 06-14-2011 12:50 AM

Curious about your weight ??
 
Just finished my GP 81" Yak 54 and the all up weight with 12s/5000 packs is 17.75 lbs. Had to add a 3/8 plate steel motor mount for proper cg. Scary !

Is this weight in the ball park for such a large electric ?

Thanks
Flyer88

kyleservicetech 06-14-2011 01:31 AM


Originally Posted by flyer88 (Post 815784)
Just finished my GP 81" Yak 54 and the all up weight with 12s/5000 packs is 17.75 lbs. Had to add a 3/8 plate steel motor mount for proper cg. Scary !

Is this weight in the ball park for such a large electric ?

Thanks
Flyer88

I'm flying a mid 2000's Carl Goldburg Extra 330 with a 12S2P A123 pack (four pounds), Hacker A60-16M motor, APC-E 19x12 prop. Power is 78 Amps at 33 Volts DC with an absolute max power of 3000 watts. It's getting about 6 1/2 minutes flight time, using about 60% of the batteries ampere hours. (Always save extra battery power in case of a go-around, or what ever. Those A123 cells can go right to left across the field, turn around and be dead stick. They quit that fast.)

This model is very close to yours, 78 inch wingspan, 1150 square inch wing surface.

General power during a take off is about 2500 Watts. (According to the Castle Creations 80 Amp HV ICE ESC data recording system) That Hacker turns the prop on the ground at about 6600 RPM, with a peak in flight RPM of 7100 RPM. Electric motors are different from gasser powered models. Make a steep climb out with a gasser, its engine will slow down. Do the same with a high powered electric, and its motor will just drop a few hundred RPM, and really crank out the horses.

This thing weighs in at 18 Lbs, 15 Ounces :oops:. That, after trying to fly its maiden flight on a 35 degree day, and forgetting to change the CC ESC to reduce power on a low battery, rather than shutting the motor off. First flight landed in a plowed field, requiring about 3/4 pound of repair work.

No, this model will in no way hover, but take off is less than 30 feet on grass, and climbout is at 60 degrees, and keep on going til you can't see the model.

So, if you've got a decent motor, and don't want to do hovering and 3D, that weight will be just fine. :D

FYI, the weights of our models pretty much increases with the cube of the model size. Double the wingspan, eight times the weight, and along with this, something like 8 times more horses required at the propeller. Problem with the larger electrics is the cost of the batteries. My A123's cost $180, direct from China. Now you can buy them through Ebay in Ohio for about $10 per cell. I'm charging mine with a Cellpro Powerlab 8, at 6S4P and 20 Amps charge rate. That takes two parallel connected 12 Volt 120 Ampere Hour deep cycle batteries.

I just bought six of these, they worked out very well: (Specify solder tabs!)
http://cgi.ebay.com/NEW-A123-BATTERY...item5ad8c47a6e

Larry3215 06-14-2011 02:56 AM


Originally Posted by flyer88 (Post 815784)
Just finished my GP 81" Yak 54 and the all up weight with 12s/5000 packs is 17.75 lbs. Had to add a 3/8 plate steel motor mount for proper cg. Scary !

Is this weight in the ball park for such a large electric ?

Thanks
Flyer88

Your weight is a little heavy but in the ball park. My 84" KMP Yak was right at 18 pounds with similar battery pack.

Whats the wing area on that bird?

Wing loading and cube loading will tell you a lot more than just a simple gross weight.

What motor and prop are you running? Have you done a bench run for peak power yet?

flyer88 06-27-2011 04:43 AM

The system ran on 12s 5000 packs and produced 3700 watts at about 74 amps. Prop is a 21 x 10

Wingspan: 81 in (2055 mm)
Wing Area: 1138 sq in (1138 sq in)
Weight: 12.5-15.3 lb (5.7-6.4 kg)
Wing Loading: 25-30 oz/sq ft (78-84 g/dm2)

Larry3215 06-27-2011 04:58 AM

Nicely done!

Generally speaking, its considered better to report the peak current/watts/etc at least 30 seconds into a motor run. That gives the packs a chance to settle down to their under load voltage.

If you were showing 3700 watts at 74 amps on 12S packs, that works out to 4.17 volts per cell under load.

No way your packs could hold that voltage under that load for more that a 1/1000 of a second so. Not a very realistic look at how it will really perform in the air.

If you let it run for 30 seconds to a max of 1 minute you will see the voltage rapidly drop and then after a bit the drop will slow down as the voltage starts to stabilize.

Thats the best number to use as far a in the air predictions and also for comparisons to other plans and setups.

For the most part, thats the way everyone else is doing it anyway :)

flyer88 06-27-2011 05:30 AM

Yes I agree .......those measure were after running the system for about 2- 3 min. I hope It gets some good runtime ?

I put about 1200 Mah back in after the test.

Flyer88

Larry3215 06-27-2011 06:35 AM

There is something wrong with your measuring gear or the way you are doing it.

Its simply not possible to get those voltage readings that far into a run. Like I said, there is no way your packs can hold that kind of voltage under load for more than a millisecond or so.

If you were pulling 70 + amps for 2-3 minutes from 5000 mahr packs, that would run them down at least 50%. Resting voltage would be down to the 3.8 volt per cell range.

The numbers you show above work out to 4.17 volts per cell or essentially fully charged.

Something isnt adding up :)

flyer88 06-27-2011 02:16 PM

No that was not a constant full out run-up for 3 min. I was checking the esc timing doing some throttle accelerations and then did some wide open runs for about 20 -30 seconds to get the max reading.

Larry3215 06-27-2011 03:16 PM

That explains the 1200 mahr number, but your original measurements are still impossible :)

They would be impossible no matter how long you ran - or didnt run - the motor.

Your batteries will only show 4.17 volts per cell when fully charged. Even running them at very low levels for 2 minutes would pull them down well below that point. You ran almost 25% of the pack out. Voltage would have been down closer to 4.0 volts per cell.

Becides that, no battery in the world is capable of holding at 4.17 volts while pulling 74 amps.

I only brought this up because either your measuring tools are wrong or your technique is wrong. If your using a WattMeter of some type, then its broken and Id suggest you get a new one.

If you are measuring the battery voltage while the motor is not running, and then measuring the current while it is running, then that your error. You cannot use a resting battery voltage and an under load current.

You must measure them at the same exact time under load or the values will not work out and you will get an incorrect watt number when you multiply them together.

A more realistic watt number for your model would be in the range of 3000 to 3300 watts. Thats roughly 3.4 to 3.7 volts per cell under load measured after about 30 seconds at full throttle.

flyer88 07-12-2011 05:30 AM

Well after a maiden flight on a 21 x 10 prop at about 3700 watts, the plane flew well with good power but was very nose heavy.

After adjusting the weight in the plane and propping up to a 22 x 10 carbon electric prop I have got the weight down to 16.50 lbs. Which I think is a very respectable weight for a plane on 12s 5000 packs. Hoping to get a few extra watts from the bigger prop too.........over 4Kw would be nice.

Have not flown it yet with the weight savings but can only expect good things to come from it !!

Happy Landings

Flyer88

http://i356.photobucket.com/albums/o...er888/yak4.jpg

http://i356.photobucket.com/albums/o...er888/yak3.jpg

http://i356.photobucket.com/albums/o...er888/yak1.jpg

http://i356.photobucket.com/albums/o...er888/yak2.jpg

Larry3215 07-12-2011 05:51 AM

Congrats!

Very neat install. I like the braided rudder/elevator leads :)

flyer88 07-17-2011 04:16 AM

8 Flight then this happens !!
 
After 8 some what decent flights , I thought the timing was out due to the odd knock while flying.

After an hammerhead I heard a knock and turned it around to bring it down for another adjustment and it burst into flames on approach.

Landed it in one piece but she got a little messy under the cowl.....damn !!

http://i356.photobucket.com/albums/o...888/YakESC.jpg

Happy Landings

Flyer88

kyleservicetech 07-17-2011 05:36 AM


Originally Posted by flyer88 (Post 823422)
After 8 some what decent flights , I thought the timing was out due to the odd knock while flying.

After an hammerhead I heard a knock and turned it around to bring it down for another adjustment and it burst into flames on approach.

Landed it in one piece but she got a little messy under the cowl.....damn !!



Happy Landings

Flyer88

Wow, that's real serious damage

What brand and model ESC was it??? (Did you have a separate receiver battery, or switching power supply BEC?)

Larry3215 07-17-2011 05:51 AM

Looks like you got lucky. That could have easily cost you the entire model.

Its a Turnigy controller.

Its interesting to me that the HV versions of the knock-off controllers seem to fail at much higher rates.


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