WheatStateHobbies

My Feedback: (1)

Hello all,

I just purchased a Northstar kit and am anxiously awaiting for its arrival via UPS. Anyway I am wanting to make it electric. But before I even begin I was wanting input from the vast amount of Northstar builders/pilots out there. I will appreciate your design/mod thoughts pro's/con's of going electric. If any body has already done this please share with me your experience and do's and don't(s) you may have. Thanks. Bill

Part 2: (May 22, 2010)
I got in the kit yesterday, but have not had the chance to look at the blueprints yet. What I'm thinking about doing is modifying the engine mount and fuel "box". Making the box big enough to hold the Li-Poly battery pack I'll need and if the box needs to be longer, push the motor forward which will help with balancing the plane. I of course will mount the ESC in this assembly and design in plenty of cooling vents. I will probably use a seperate battery to power the reciever as this will help with the balancing the aircraft and reduce the amount of "dead" weight that I will probably need to add! Any thoughts by anybody? Thanks. Bill

Himat

If you check out the Arrow thread in this forum there are examples of electrictrified Arrows. Even more info in the old, first, Arrow thread, but beware, it is a long thread to read. The Arrow is very much a tail less Northstar with the same power requirement and the set up from an Arrow could be adapted. As far as I remember, all electric Arrows did have the battery (and the ESC?)in the hull and long wires to the motor.

If I where to make a modified electric Northstar Iwould delete the motor pod in the tail to build a lighter tail and build a pod on the CG with the motor pusher style. (No problemto getpusher propellors for electric, just reverse the rotation of the motor and use an ordinary prop.) The battery could then go in the hull in front of/under the new motor pod.

LADDIE

Bill. If you let me, I like to suggest to you to install the motor batteries inside the radio compartment. The weight of batteries will be enough to balance the model. On top of that, you will end up with the model that is et least pound lighter then glow powered N/S.
I am enclosing the pictures of my electric N/S I built three years ago. As you can see I mounted elevator servo inside the nacelle. I had my speed controller inside the nacelle as well. I had no problem with that set up but some manufactures of speed controllers are against long battery wires.
Since then I have been mounting the speed controller close to the batteries and run long motor leads.
Good luck.
LADDIE

WheatStateHobbies

My Feedback: (1)

Thanks! Any problems with the wires or ESC getting hot? What is your power plant configuration? How well does it perform compared to a glow version and what is your runtime? Iknow that's a lot of questions, but thank you for your input. Iknew Icould not have been the first person to think about doing this. Thanks again. Bill

LADDIE

Bill
I am using AXI 4120/18 motor and 6S 3000mA or 5000mA batteries and 60A Castle Creation or Jeti 60A ESC. I am drawing 40 to 45A at full power. Usually, when flying the part of the flight is at full power and part at cruising. This gives me approximately 10 minutes flight. As far as comparison between glow and my electric NS goes, I can keep up with some glow powered but not with most of them. My aim was to have fast enough NS not the fastest one.

alasdair

My Lochstar model is (obviously) Northstar based, but with many changes (aerodynamic structural and cosmetic).

My motor is Chinese, Tower Pro 3520, 44.7 mm dia, 58 mm long, 237 g weight, Kv 1000, rated 600 watts
Turns APCE 10x5 at 13500 rpm on a freshly charged Kokam 3200 mAh 5S taking 55 amps (static) and that's just under 900 watts. It will unload in the air and as the battery loses its charge peak.
All the radio gear/servos are up front, the 60 Amp ESC is beside the battery aft of the cockpit and forward of the step, to achieve balance. The ESC has a little ex-computer cooling fan that takes a few mA from the separate radio battery, and I extended the 3 motor wires up through the fin leading edge.

Performance is like that of a good 40, rather than a howling 53. Adequate but not startling.
I expected to save weight but it has tuned out at 3250 g (7.15 lb), about the same as the IC version.

I built mine such that I could convert to an Irvine 53 with mini pipe later, but I will leave it electric for now, until something burns out.

P.S. I have just moved the Rx battery to the aft end of the nacelle/tank bay to help with balance. Now I can fit a 5000 mAh battery.

Strykaas

Laddie,

Do you think a more powerful setup could make your e-NS faster than the glow ones ? The e-NS is sleeker, and theoretically faster then, as there is no engine cylinder sticking out the fuselage lines... What do you think ? I see no real reason why a e-NS would be slower.

LADDIE

Yes, I think it would. Personally, I did not explored what motor is on market that could give NS more speed.
Laddie.

Bob93447

I have been doing some research for my own Northstar which has been waiting some 20+ years to be built. Recently Hyperion came out with a line of high power, high KV, lightweight motors. Of particular interest if you are after pure speed is the Zs3026-06. Its a 1100 KV motor rated at 1500 watts. With a high pitch 10" prop you should be able to get a pitchspeed of >100mph using a 4s setup. Optimally the motor mount should be redesigned to provide optimal cooling and less drag. The downside would be short duration and high prop noise but you should be able to give the .50's a run for their money. Scorpion make a similiar motor and you can propably get a Heli motor from HK to do the same thing.

Bob

Strykaas

Thanks a lot Bob for your input. I'm looking into it [8D]

Fidelity101

My Feedback: (13)

I went with an eflite 60A esc, turnigy match .46 670kv motor, 6S 5800mah pack and apc 10x10 prop. I get 52A at WOT but now im having premature engine cutoffs after 1-2 minutes of flight. Might be wire length issues or low voltage cutoff

Strykaas

Maybe your esc is fried ? Thanks for your input.

lupy

My Feedback: (3)

sounds like a heat issue, the eflight is a nice esc, but that's pretty close to the limits. I use one in my neptune with a eflight .32 and 4s at 40A max. there is only a little airflow, and after a 4500mah flight, it comes back pretty warm, but has never cut out. With 6s, and 52A, unless it's right out in the wind, I think it will cut out. In extreme cases, some of these will cut power to the RX too, so be carefull. I had a Plush 60 catch fire using the rated 6s at only about 20A.

I have been kicking around bulding an electric NS myself. They look like a lot of fun. I don't need blistering speed, so electric should work fine.
Keep us posted.
Ken

Fidelity101

My Feedback: (13)

The esc is barried inside the rear box with zero airflow...so I'm guessing you're right. I was thinking of carving some air inlets on top and the sides in order to improve flow. Also, the 10x10 apce prop is barely enough thrust on a 670kv motor. It takes off from dry grass with a little push and my model weights just over six pounds with the lip and 5 pounds 2 ounces without. I have a 10x7x3 prop I want to try as I don't like the idea of staying 75% throttle to maintain flight. If I had to do this again, I'd move the engine box up a half inch and use an 11x7x3 prop with this beauty.

Also purchased a built and painted north star for $20 at the last swap meet. Its beat up and weights a ton with the paint, but I might try for a spare gas north star to compare flight performance. Using a evolution. 52 engine that also cost me $20 bucks!

alasdair

The ESC problem sounds like overheating.
In my Lochstar (above) the ESC was in the fuselage near the lipo (as I was advised to do). I had a cooling fan on the ESC.

If the ESC is in the tail there is probably not enough air volume to make a fan viable so I'd suggest mounting it on a finned heatsink whose fins extend outside the model to dissipate heat.

lupy

My Feedback: (3)

There are a lot of reports from MFG's warning not to add length to the battery side of the esc, A number of people have also reported heat, fires and explosions from doing this. Others have done it without issue. I know it's a pain to add wires to a Northstar, but that might be part of the solution. I also think the 10X10 prop is stalling at low speeds. On my Neptune and Mariner (I know, not as fast) I used to run a 12X10, but went to a faster motor with a 12X6, and had lower amps, better thrust, same top end. Given how cheap mid line outrunners are these days, you could try several to see what works best. For almost 1100watts you should have plenty of thrust and shouldn't need 75% throttle to stay in the air. You may be saturating your magnets which will burn a lot of power and not give much back. Do you have an RPM reading?

Laddie, curious what prop you were using, that Axi is a pretty slow KVA motor, but a very nice one.

Fidelity101

My Feedback: (13)

If the wires are too long between the speed controller in the motor, you will have timing issues. ,If the wires are too long between the speed controller and the battery, you'll have some really high ripple voltage which can cause all of the items you mentioned. Since I do not want to put the speak controller in the middle and run more wires , I'll have to take my chances as is. From what I've read it's better to extend the battery wires than it is to extend the wires between the speed controller and the motor.

The motor is only 670 k v. Since I can only use a 10 inch prop , I used the largest pitch possible in order to get the amperage up . I know this is probably a bad idea so I'm going to try my 10 by 7 by 3 blade. I also plan on adding some air scoops to both sides in order to get some air over the speed controller. Currently, the speed controller seas 0 air flow.

jollyroger

My Feedback: (6)

I've seen a couple electric North Stars and both flew quite well. One was powered by a Scorpion 3026-710 and 5S Hyperion G3 pack. Went like scat. I would not hesitate to mount the motor where it is supposed to go. In fact you may still have to move the battery pack back a little as the Scorpion motors weigh nowhere near as much as a glow motor of equal power.
There are great planes to fly as I was very surprised to hear how well they handled, but then again It is a Laddie Mikulasko design and he don't design no trash.
BTW: ModelAero makes a foam version of the same plane with permission from Mr. Mikulasko and is called the Polaris XL. slightly smaller than the North Star and powered by a 200 watt motor. Flies exceptionally well.
It's going to be a difficult decision to choose between the two. Guess I'll wait until Toledo Show and make a choice.....buy both?

Mustang Fever

My Feedback: (2)

I'm about finished with my "e" Arrow, and I think the issues with it are about the same as the Northstar.

Power: I'll be using a Rimfire 32 on a 5S pack. Should turn a 10x5 MAS 3 blade at 13,000 RPM or so. (65mph and 5.7# thrust) This uses about 40A, so the wattage is about 750 on a six pound airplane.

I built a 50% electric Arrow some years ago, and found out the hard way that putting a light electric motor in the back means the battery pack must be WAY to the rear of where it would go in a glow bird. The pic shows the battery box for the big E Arrow:

cajun1

WOW, am I glad I found this thread.

I have a 15 yeart old NS kit I am starting to build and power with electric. So, any help I can get I will appreciate.

Mine will be strictly float use, and I plan on redcucing weight as much as possible while keeping structural integrity.

I use mostly HK power systems and would appreciate anyones proven suggestions for HK motors/Esc.

I'll be lurking about.

Thanks.

WheatStateHobbies

My Feedback: (1)

Thanks for the input, the bad thing is Ihaven't had time to work on that project, other than to buy the kit! *Maybe* I'll be able to get to it this year......

Bob93447

I also have an older BUSA Northstar kit that I am planning to electrifly. I'll start work this fall, after I'm done building a Polaris XL and a 100% Polaris. Looking at the NS kit, it seems like it should be possible to substantially lighten the motor mount as well as provide room for both rudder and elevator servos. Has anyone developed a design for a new motor mount? I have a Hyperion 970 KV, 200 gm motor that should provide enough power and its substantially lighter than any of the glo engines that were used to power this plane.

WheatStateHobbies

My Feedback: (1)

Cajun,
When I first started this thread, Igot a response from Laddie (the designer of the NS). He had already done and he sent me a modified rudder plan. He basically made the rudder an inch or two taller, re-enforced it. The taller rudder/vertical stabilizer gave it the prop clearance needed for the electric motor/prop. I'll look through my email archive and forward that on to you. If I also remember correctly he kept the LIPO's up front. Good Luck, Bill

Mustang Fever

My Feedback: (2)

I'd forgotten I posted on this thread. The following comment is now inoperative, as they say:

"Power: I'll be using a Rimfire 32 on a 5S pack. Should turn a 10x5 MAS 3 blade at 13,000 RPM or so. (65mph and 5.7# thrust) This uses about 40A, so the wattage is about 750 on a six pound airplane."

If you try to get out of a Rimfire 32 what the Tower website says it will do, it will melt. I melted two of them, and ended up with a Turnigy G46-670. This, with an 11x7 3 blade MAS on a 5 cell gives the E Arrow sparkling performance. 38A, 11,000RPM (72mph, 7# thrust) Only wish I'd made my battery box a little bigger. Can only get a 3000 pack in there. However, anything bigger would weigh more, so the longer flight time would be offset by lower performance.

This combination should work well on a Northstar. If you really want it to wail, you could use one of the Turnigy G60 motors on 6S.

cajun1

Thanks all for the info.

I have been looking at using a 50/60 size Hk motor and a 5S/6S Nano pack. This design, when powered with some punch, really goes and the 60 looks promising, if it doesn't add too much weight. It probably would take a 6S 5000 Mah battery to do the job.

I like the idea of making the fin taller to utilize a larger prop with the 60 motor. No use having the power if it's limited by a too small prop.