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  1. #1

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    Hobbico Twin Star conversion


    I'm expecting a pair of Hobbico Twin Star ARF's in the mail any day now and am going to convert one to electric.
    Looking for recommendations for power. Factory recommends 25 to 40 glow engines.

  2. #2

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    RE: Hobbico Twin Star conversion

    I'm waiting on mine also. Power will be two Jeti Phasor 30/3 running on 3s power. The small prop size seemed to me to dictate a DD setup. I'm looking for speed and not max thrust.

    John

  3. #3
    guapoman2000's Avatar
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    RE: Hobbico Twin Star conversion

    Ops///[&o]

  4. #4
    Moderator Greg Covey's Avatar
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    RE: Hobbico Twin Star conversion

    Carlos,

    I think John's approach of using a direct drive brushless motor is a good one. There are many to choose from and shape or size can be a determining factor in your decision as well as cost.

    Let's look at the Hobbico Twinstar ARF specs:
    [ul][*] Wingspan: 56" (1420mm)[*] Wing Area: 560 sq in (36.1 sq dm)[*] Weight: 5 - 5.5 lb (2270g - 2490g)[*] Wing Loading: 21-23 oz/sq ft (64-70g/sq dm)[*] Length: 50" (1270mm)
    [/ul]

    The key spec. here is the flying weight of 5lbs and the fact that it is a twin motor design. For great performance, we'll want 75-100 watts per pound or about 400-500 watts combined input power. This means that each motor should provide 200-250 watts.

    The AXI 2820/10 is more than we need on a 10-cell NiCd or 3-cell Lithium pack with a 10x6 prop as it provides about 300 watts input power. A single 3-cell Kokam 3.2AH (20C) pack or 10-cell GP3300 NiMH pack could power the entire plane.

    Keep in mind that this is just one example of many solutions.

    Good luck!
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    Visit my Web Hangar at www.gregcovey.com/rc.htm

  5. #5

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    RE: Hobbico Twin Star conversion


    Thanks Greg, good info.
    Chuck

  6. #6

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    RE: Hobbico Twin Star conversion

    I plan to electrify a Hobbico Twin Star. Using brushless motors with 2 ESC's I understand that you must disable the BEC and install A ubec. I need some info on the wiring setup. I will be using Li-Po batteries, a Thunder Power 3S3P, 6000 mah.

  7. #7

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    RE: Hobbico Twin Star conversion

    Greg Covey,
    Which ESC or ESC's would I use with the Axi 2820/10 motors and a 3S3P 6000 batt.?
    Chuck

  8. #8
    weskel's Avatar
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    RE: Hobbico Twin Star conversion

    I also have atwin star awaiting build, I am completely dumb to electrics, I need all the info i can get.


    Weskel
    I can crash any plane out there, Guaranteed!!!

  9. #9
    weskel's Avatar
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    RE: Hobbico Twin Star conversion

    Greg,

    I just checked out your recomendation on the motors from hobbly lobby, is a "cheaper" alternative to the brushless motor you suggested, it looks to me like it would cost $188.00 for the motor and the ESC. That would be a little rich for my blood.

    Weskel
    I can crash any plane out there, Guaranteed!!!

  10. #10
    Moderator Matt Kirsch's Avatar
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    RE: Hobbico Twin Star conversion

    When you get up into the larger electrics, good power doesn't come inexpensively. The AXi combos from Hobby Lobby are actually some of the least expensive brushless options at that particular size, and you still haven't priced batteries yet...

    You could go with a pair of geared Kyosho Endoplasma brushed motors at $20x2 (motor) + $15x2 (gearbox) + $60 (50A ESC), plus a 10-cell 3700mAh NiMH pack ($70) but performance won't be much more than acceptable, and flights will run 6-7 minutes.

  11. #11
    weskel's Avatar
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    RE: Hobbico Twin Star conversion

    Thanks for the info, I am completelyt stupid when it comes to electrics, I will just slap some glow engine on it and hang on.....


    Weskel
    I can crash any plane out there, Guaranteed!!!

  12. #12

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    RE: Hobbico Twin Star conversion

    See my thread in "General Discussion" titled "Counter Rotating Props" (right now on page 2) for pictures and descriptions of my T-Star electric conversion.
    Thanks for looking.

  13. #13
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    RE: Hobbico Twin Star conversion

    Hi guys

    Sorry to wake up this thread from the death but I found it vary useful.

    Well, I am flying my TwinStar for 3 years or so,
    After all the original poor covering film melted I decided to re cover it with Oracover and a new scheme from my own as you can see from the photos.
    (don’t worry, the cowl is painted already)


    The next change I would like to do is convert it to electric.
    Well I dond want to get crazy with the costs. Just have some fun.

    If you will not recommend me another way, I will buy 2 motors (turnigyTR 35-42D 1000kv and plush 40A ESC) from hobby king.
    The recommended battery pack is 2-4s lipo.

    How do you guys set up your models? One big pack for both motor, or one smaller pack for each motor? What capacity? How many cells?

    Thanks in advance

    Ram
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  14. #14

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    RE: Hobbico Twin Star conversion

    I'm going to re-reawaken this thread.

    I purchased one of these at an auction this weekend. It was glow powered.

    I am contemplating a pair of Rimfire 42-50-800, each with a 3S (around 2200-2500 mAh) battery pack, and CC 60 (or 45) ESC.

    I haven't decided on a prop yet, I'm leaning towards a 10x5 3-blade. I think I'd have ground clearance problem with anything bigger than a 10" prop.

    I will probably end up gutting the nacelles. Then moving the firewall forward, reducing the standoffs, and providing more room for battery/ESC.

    Comments?

    I am definitely going to put this motor on a test stand and watt-meter it to see what I get.
    β€œIt is possible to fly without motors, but not without knowledge and skill.\" - Wilbur Wright

  15. #15

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    RE: Hobbico Twin Star conversion


    I had Axi 2820-10 motors with EPKokam 14.8 volt 2000 mah batteries and a Jeti Advance 70 Plus ESC. on my third T-star, flew great.

    Had the same stuff in my Urovtich OV-10 Bronco, also flew great.

  16. #16

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    RE: Hobbico Twin Star conversion

    I've revised my motor selection..

    I am now considering the Rimfire 42-40-1000s.

    I thought about going with AXI 2820/10 motors, but the only online place I know of (I won't mention names) is out of stock.. as usual... and having purchased things from them in the past, it could be a day, a week, or a year, before they get the motors in stock again.

    The new rimfires more closely match the AXI motor.

    I think when I rebuild the nacalles I'll keep the firewall back a little and put a stand-off between it and the motor, I'm thinking about 3/4".
    If I have to swap in a longer can motor, I won't have to move the firewall a second time.

    Oh.. does anybody know the covering of a twinstar? Is is Ultracote? Monokote? Or something unique?
    β€œIt is possible to fly without motors, but not without knowledge and skill.\" - Wilbur Wright

  17. #17

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    RE: Hobbico Twin Star conversion


    Can't remember what the covering is, the first generation T-star's were covered with "shelf paper", real junk.

    Do a search for the Twin Star and you should be able to come up with something.

  18. #18
    Mustang Fever's Avatar
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    RE: Hobbico Twin Star conversion

    Carlos:

    The twinstar would be a hotrod with a pair of Rimfire 10s, a 4000 3S pack, and 10x6 MAS G/F counter rotating props. (45A ESCs)

    You save so much weight by going to electric on a twin, that I'll bet you could get it down to 5 pounds or less RTF.

    I have this same power setup on a 3 pound converted sloper (P-51) and it honks and will fly around for almost 20 minutes at reduced power settings. (I have a 2200 3S pack)
    Bob Hunt

    \"Progress is marked by great smoking holes in the ground.\"
    -Gen. Chuck Yeager


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