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Author Topic: Golden Age electric  (Read 659 times)
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RandyW
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« on: March 31, 2019, 03:51:36 AM »

Construction of my 1/2 A electric Cee Bird is well along however a photo I found on line keeps haunting me. A 9 foot Cee Bird would have over 10 square feet of wing area. The original flew with a McCoy .60 two stroke, a pretty hot mill back in the day. Any suggestions on what size electric propulsion system to use? Thanks
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Scottl0413
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« Reply #1 on: March 31, 2019, 09:23:11 AM »

Randy, in response to your request for a pwr. source, it would be helpful if you could let us know the wing area? If it's around 250 sq's than I'd recommend an RCX H2205 (2950 kv) or you could drop down to the 2300kv version depending on how hot you want it to  be, on a 3 cell lipo battery, spinning a 5x3 APCE prop, and you'll probably need an 18 amp speed controller! you could probably use the same motor with the smaller version but I'll look at a lesser kv rating.

Scott
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RandyW
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« Reply #2 on: March 31, 2019, 03:03:53 PM »

Scott
The 1/2A Cee Bird has 392 square inches and the rules allow only a 2-cell battery pack.
I was hoping for suggestions for the larger bird which has a bit over 10 square feet of wing area
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lincoln
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« Reply #3 on: March 31, 2019, 08:34:16 PM »

Judging by my RC experience, if you can estimate the finished weight, 100 watts per lb will give you a STRONG climb, maybe hard to trim. I'd guess 1,000 fpm (!) at that power level, with a good, efficient prop.  50 watts per lb would give you an adequate climb, maybe more than adequate if the wing loading is light. If it was mine, I wouldn't go anywhere near 100 watts/lb unless it was RC and for competition purposes, with a time limit on the climb. I have a model with comparable power to weight that gets to 200 meters in less than 30 seconds!

Not sure how hot that old McCoy was. If it put out 1 hp, then 700 or 800 watts into a good brushless ought to be more than enough. Maybe overpowered, since the right electric would probably have a bigger prop and lower rpm, making it more efficient.
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prisms2
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« Reply #4 on: April 02, 2019, 10:31:50 AM »

Randy, My fathers 9 foot canard was 108"x12" giving it a 9:1 aspect ratio wing and 1300 square inches of area. The 392 model was deigned in the late fifties to a different set of rules than we have now. If you look at some of the designs of the day it was common to see 1/2a models that had around 400 square inches of area. In the mid sixties I scaled down my dads original design to 252 square inches with a 7:1 aspect ratio(42"x6") with a Holland Hornet 049 for power. About that time my father built two models with a wing area of 216 square inches (36"x6") at a 6:1 aspect ratio. One of them was powered by a Wen Mac Hot Shot and the other was powererd by a Cox TD 049. they were very fast in the climb. This size would lend itself nicely to either a E-36 model or a Golden Age model. As you know the 1300 square inch model does not qualify for the Golden Age event but if you build and fly one it is one of the most amazing models to see in the sky.I still have my father's 1300 Cee Bird in my garage and it brings back a lot of great memories. Keep us posted on your progress. All the best,Jim Taylor
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RandyW
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« Reply #5 on: April 07, 2019, 06:32:06 AM »

Thanks so much for the info Jim! I had assumed the 9 footer was a direct 192% enlargement of the 1/2A model. Would have had a bunch more wing area. Just finished the the wing structure today, just needs sanding and  polyhedral. Lots of little pieces but sure is pretty.
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flydean1
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« Reply #6 on: April 07, 2019, 03:51:46 PM »

Jim,  I would really like to know more about the 216 sq in model.  Any photos or plans anywhere?

I once timed one of Doug Joyce's FAI Power (I prefer names to F1-whatever) models. 
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RandyW
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« Reply #7 on: April 09, 2019, 05:31:04 PM »

Cee Bird structure is complete! 152 grams with motor. On to covering
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Scottl0413
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« Reply #8 on: April 10, 2019, 07:26:33 AM »

Randy, beautiful build!!! What motor do you have on it? Are you planning on flying it in E36?

Scott
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prisms2
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« Reply #9 on: April 10, 2019, 10:12:25 AM »

Dean, somewhere I have some photos of the 216 model but it may take some time to find them. My father passed away a year ago February and my family members and I boxed up a lot of his model stuff and I brought it to my home in Oregon. When I find the pics I will bee glad to post them. The 216 model was 36"x6" in the wing and the stab was 35% I believe. Many of his plans were lost in a shop fire right after we came back from the 1968 Nats at Olathe. I'll keep looking.
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prisms2
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« Reply #10 on: April 10, 2019, 10:14:14 AM »

Randy, Great lob on the Cee Bird. Please keep us updated on your progress.Jim
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RandyW
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« Reply #11 on: April 10, 2019, 07:42:43 PM »

Scott, I'm using a hexTtronk 1700kv 24 gram outrunner from Hobbyking. It swings an 8x3.8 slow flyer prop. Thrust claimed is 400+ grams on a 2C lipo pack. With a wingspan of 58 inches its too large for E36 but qualifies for golden age
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