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Electric Conversion for Kyosho Gee Bee Z

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Old 03-24-2004, 12:59 PM
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Default Electric Conversion for Kyosho Gee Bee Z

Hello folks...

This is my first inquiry here on RCU and as a relative newcomer to electric R/C I hope not to embarrass myself too much! I have been reading the posts here for a year or so now and am very impressed with the willingness of others to help those who are just getting hooked!

I would like to consider an electric conversion for Kyosho's 40 size Gee Bee Z. I already have the ARF and am planning on installing a Williams Brothers scale Wasp radial engine in the cowl as the only embellishment.

Anyway, I sure would appreciate your thoughts on how to go about this conversion. I would like to use Lithium Polymer batteries but other than that, I have no preferences. Also, I am pretty much a sport flyer so I'm not worried about pylon racing just yet!

The model's (glow) specs are:
Wingspan: 56.4 in (1430mm)
Wing Area: 511.6 sq in (33dm2)
Weight: 6.4 lb (2900g)
Wing Loading: 28.5 oz/sq ft (87g/dm2)
Length: 36 in (915mm)

I am wondering whether a direct drive or geared drive would be the way to go?

Any thoughts from the experts is greatly appreciated!

Many thanks in advance for your thoughts. This is a terrific way to learn!

Curt Hughes
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Old 03-24-2004, 01:34 PM
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Greg Covey
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Default RE: Electric Conversion for Kyosho Gee Bee Z

Hi Curt,

The Kyosho GeeBee Z 40-size ARF is a scale beauty! Tower Hobbies sells it [link=http://www2.towerhobbies.com/cgi-bin/wti0001p?&I=LXWW23&P=7]here[/link].

Today, there are many ways to convert your GeeBee Z to electric power. Some favor performance, some service, while others favor cost or simplicity. It is up to you to decide your order of priorities and then determine which one is the best choice for you.

Hopefully, your thread will produce many suggestions for you to choose from. Additionally, on your own, you can compare any of the exiting conversions for equivalent application to your plane. For example, look for a conversion/review on another .40-size ARF. Is it a similar type of plane? Weight? Wingarea? Airfoil? Is the performance what you expect? What is the cost? and so on.

I'll start the suggestions...
[ul][*] Hacker B50-13S, 6.7:1 geared, on 16cells CP2400 and a 15x10 APC e-prop[*] MaxCim 13D motor geared 4.3:1, on 16cells CP2400 and a 15x10 APC e-prop[*] AXI 4120/14 direct drive on 16cells CP2400 and a 14x7 APC e-prop
[/ul]
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Old 03-24-2004, 04:27 PM
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Default RE: Electric Conversion for Kyosho Gee Bee Z

Curt,

For more examples, check out my own [link=http://www.gregcovey.com/electric_conversions.htm]Electric Conversions[/link] page.

Good luck and welcome to RCU's Electric Aircraft Universe!
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Old 03-25-2004, 09:43 AM
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Default RE: Electric Conversion for Kyosho Gee Bee Z

Greg...

Thanks very much for your suggestions. I emailed Zb at Esprit and he suggested the following setup:

Mega 22/45/3E, 12x6 prop, TP6000 5S4P battery

I was thinking AXI or a Hacker motor myself. I definitely want to go with lithium power.

I just finished converting a World Models Rambler 30 to elecric with the help of Zb at Esprit and I am going to try and make the maiden flight today sometime, here at the Air Force Academy. It is spring break here and I have three huge fields to fly off of with a road between them that I can use for a runway if I want a hard surface.

Also, I wanted to mention how very helpful your posts and reviews on RCU are, especially for the newcomer. Your reviews are nicely done and the photos and textual descriptions you provide are enough that anyone interested in getting started on a similar project can just "follow along" with whatever it is you're building and feel a sense of accomplishment. Let's face it, converting conventional glow or gas powered models to electric power systems can be very challenging for the newcomer as there is so much to learn and so many decisions to make, all of which can be costly if made incorrectly!

Please keep up the terrific work and keep those reviews and photos coming!

Curt
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Old 03-25-2004, 03:08 PM
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Default RE: Electric Conversion for Kyosho Gee Bee Z

Curt,

Thanks for the kind words. We try to publish our results here for exactly the reason that you conveyed...to help people make the right choice for themselves without being dictated too. It isn't always easy and we don't always please everyone with the results.

There are so many choices available now that I can't try them all, even if it was affordable, there wouldn't be enough time to do it. Hopefully, by pooling our experiences, a general consensus emerges.

I don't have any experience with the Mega 22/45/3 series so I can't help you there. The power output level and the prop size looks a bit shy for real performance on your Gee Bee.

Good luck with the Rambler test flight!
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Old 03-25-2004, 04:11 PM
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Default RE: Electric Conversion for Kyosho Gee Bee Z

Hi Greg and all...

I suppose I should have posted this under a new thread but it is in reference to my maiden flight of my Rambler 30 which I did about an hour ago and is mentioned in my earlier post. My apologies if I am outside the posting rules. Please let me know.

Anyway, I converted a Rambler 30 ARF to electric and asked Zb from Esprit to recommend a power system for it. I bought an AXI 2820-12 motor, a Hacker Master 40-3P ESC, a Thunder Power 4S3P 6000 mah battery, a UBEC, APC 11X7 prop, and aluminum motor mount. Zb wired the system all up for me. Terrific service!

I went out to fly its maiden flight and it flew great for about 4 minutes. I was flying with about half throttle for most of this time and I had just pulled out of a loop and was at low throttle and went to power up at the finish of the maneuver. I heard a strange “squawking” sound and then the motor just quit. I landed dead stick and when I picked up the model I could smell something strange… like something had burned. I moved the throttle stick and the prop just sort of wiggled back and forth about a half inch or so but wouldn’t rotate. I took the wing off immediately and nothing appeared to be hot. In fact, the battery was barely warm. But, I couldn’t get to the motor or ESC as I didn’t have the tools handy to remove the cowling.

I was at work at the time and brought the model to my office to disassemble the nose. When I put my nose to the motor and sniffed, I noticed that “burned” smell that I mentioned before. Could the motor have burned out? ESC? Well, I called Esprit awhile ago and asked if I could send the system back for inspection. It will go out tomorrow and I'm sure the guys at Esprit can help me.

Also, I had to add 6 oz of weight to the nose to get the model to balance and I noticed that the next size AXI (4130 series) weighs almost exactly the weight of the 2120 plus the 6 oz. of weight. It seems to me I would be better off having a larger motor in the nose than useless weight. Do you think that's a good idea? Of course, I'll have to buy a larger ESC but... it's always something!

I might add that this was my first conversion to electric flight with any model and I can't believe how much fun I had in just those four minutes. Now I'm grounded until the system is returned.

Frustrated...

Curt
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Old 03-25-2004, 04:55 PM
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Default RE: Electric Conversion for Kyosho Gee Bee Z

Curt,

The likely possibilities are that the motor failed, the motor and ESC are not very compatible, or there was a problem re-sensing the motor position after you went to low throttle and the ESC interpreted a momentary off position.

When you throttle up, the sensorless ESC senses the motor position by waggling the rotor back and forth. It then starts turning the motor in the proper direction after it is satisfied.

I have seen this problem once before and it burned out my motor controller. Ask to see if there are any programming modes for timing in your ESC. Perhaps a different ESC vendor will make a difference. People have been happy with the Jeti Advance and Castle Creations ESCs. Generally, most people use Hacker Master ESCs on Hacker motors that are not outrunners.

One final note, for a 4s Lithium pack, your 11x7 prop is too big. You should be closer to a 9x6 prop. It is possible that the motor magnets got too hot and the came loose from the glue.
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Old 04-02-2004, 11:18 PM
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Default RE: Electric Conversion for Kyosho Gee Bee Z

I am almost finished with this very conversion. I am using an AXI 4120 /18 with a 14X9 or 14 X10 prop. I am using 6s4p thunderpower packs. I'll post after first flight. It will take me a few more days, I just got the motor in the mail today.
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Old 04-07-2004, 11:26 AM
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Default RE: Electric Conversion for Kyosho Gee Bee Z

Mookie

Sounds great! I'm looking forward to your posts!

Curt
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Old 04-10-2004, 01:25 PM
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Default RE: Electric Conversion for Kyosho Gee Bee Z

Funny, this plane sat on the market for a while with no one converting them, now there will be three as I am a couple days away from finishing mine, if I can ever get to work on it.

I am using a 4120/14 planning on 14 cells at first as I dont know how it will balance on lipos.

I am curious how you are planning on mounting lipos and other batts?
Kirby
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Old 04-20-2004, 08:30 PM
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Default RE: Electric Conversion for Kyosho Gee Bee Z

Ok guys I finished the GEE BEE. That's the good news; the bad news is it flew for 9 seconds then dove into the dirt. I think the cg was off. I checked it and it was close but it flew like a wild horse. It was a crazy ride and I will post the video so all can enjoy the fury. Turned out one of my wheels was binding which pulled me towards the BIG crowd. I pulled up too fast to avoid killing anyone and stalled but saved it only to have it spin later after I had some good speed. Only the front of the plane is damaged. I can rebuild it stronger, faster.....I'll post the video ASAP.
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Old 04-20-2004, 09:28 PM
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Default RE: Electric Conversion for Kyosho Gee Bee Z

Sorrry to hear that. I understood this plane to be very CG sensitive, and I can understand why. Out of curiocity, exactly where is was the CG set?

I am almost done with mine and hope to maiden it this weekend, but weather is not looking promising at the moment.

Also where did the batts end up?

I ended up putting 7 cells inside the fuse and 7 cells under the motor mount. I am still trying to get it to balance. I dont want to cut the fuse for cooling, but it looks as though I will have to now.

Thanks for the info;
Kirby
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Old 04-21-2004, 03:28 AM
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Default RE: Electric Conversion for Kyosho Gee Bee Z

http://www.rcgroups.com/forums/showt...79#post2080179

Here is a link to the Building thread I jsut put up over there.

Kirby
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