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Old Jan 07, 2012, 07:52 PM
Bypass Ratio = Infinity
scatsob's Avatar
United States, NC, Jacksonville
Joined Apr 2006
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Hey Walter, say hi to the guys at the field for me. I actually called them last week and the person on the phone I talked to said that the GEN 2's would be the same as upgrading the GEN 1's...about $200. (GEN 1's plus the board is $200) I will probably just wait until summer when all this is sorted out and make a decision then. The only problem then will be I can either spend $200 on the retracts or $200 on the new PC-21 they have coming out.

On a building note, I got the servos in that I plan on burrying in the elevators so when I start that I will start posting build pictures again.
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Old Jan 08, 2012, 07:51 PM
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TripleW's Avatar
Prescott, Arizona
Joined Feb 2010
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Huh, That's not what the youtube video said. I'll see if I can find it tomorrow.
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Old Jan 08, 2012, 10:00 PM
Bypass Ratio = Infinity
scatsob's Avatar
United States, NC, Jacksonville
Joined Apr 2006
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If you are talking about the video they did comparing the v1 and v1 with board I have seen it on TBM's website, I just didn't pay attention to what he was saying at the end.
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Old Jan 10, 2012, 08:11 PM
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United States, NC, Jacksonville
Joined Apr 2006
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I made some headway with the power system. I finally got the rear rotor to stop rubbing against the stators but it took some persuasion. Weíll see how it runs in the next day or two, and I plan on taking it up to WOT to see that I get. I also got both spinner back plates drilled and mounted. I was going to try to find someone with a lathe to do it properly but that was getting nowhere and I figure Iíll have the time and money to do things properly when I am older. So I just picked the drill bit that was just oversized for the hole in the back plate and stepped up one bit at a time until I got to 12.7mm. Then I used the 12.7mm but to ream out the hole to the 13.2 mm it needed to be. I did the same for the front back plate to get it to 8mm. Here is a picture of todayís efforts. Tomorrow I will cut the blade holes in the front spinner and get that mounted up. Then Iíll put it on the plane and see how she runs ....and looks.
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Old Jan 11, 2012, 10:03 AM
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scatsob's Avatar
United States, NC, Jacksonville
Joined Apr 2006
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I got everything buttoned up this morning. There is no discernible wobble in the front spinner so well see how it runs. I have it ready to run right now I am just topping off some batteries. I took some pictures with the cowl on to see what the final product will look like and one with the front spinner off for reference. Looks pretty good .

I am a little anxious for the testing. I want the amp draw to be in the 60-70 range but I am worried it is going to be more. I am also worried about the differential between the front and rear motors. I guess if it is substantial then I guess flight time will be driven by the motor that draws the most current.
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Old Jan 11, 2012, 11:25 AM
Scale Builder
United States, AZ, Litchfield Park
Joined Jul 2002
2,577 Posts
Really exciting and interesting project scatsob. Hope the testing goes the way you want it to.
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Old Jan 11, 2012, 12:54 PM
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United States, FL, High Springs
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so freakin cool!

just love the looks of this bird, can't wait to see and hear it fly
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Old Jan 11, 2012, 05:06 PM
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scatsob's Avatar
United States, NC, Jacksonville
Joined Apr 2006
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Here is a short video of the full throttle test.

23 volts
65 amps
~3kW total power

CR50 brushless contra-rotating full-throttle trst on 6s (1 min 7 sec)
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Old Jan 11, 2012, 05:36 PM
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TripleW's Avatar
Prescott, Arizona
Joined Feb 2010
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Cool Scott!
Was the brake on or do those motors stop quick?
You could parallel the batteries so the voltage stays equal.
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Old Jan 11, 2012, 05:41 PM
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Leduc, AB, Canada
Joined Oct 2008
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Holy Hanna!! THAT WAS AWESOME!!

Cheers,
Peter
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Old Jan 11, 2012, 05:53 PM
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United States, GA, Newnan
Joined Mar 2008
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Cool!!

You know you have plenty of power when eveything in the room starts flying around
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Old Jan 11, 2012, 06:11 PM
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Prescott, Arizona
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Including the Transmitter!!
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Old Jan 11, 2012, 06:50 PM
http://roys-rc-tv.webs.com/
Basingstoke Roy's Avatar
United Kingdom, England, Basingstoke
Joined Oct 2005
455 Posts
No lack of grunt there, looks like your good to go
I do love the sound of a contra, sweet
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Old Jan 11, 2012, 09:51 PM
Bypass Ratio = Infinity
scatsob's Avatar
United States, NC, Jacksonville
Joined Apr 2006
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Quote:
Originally Posted by TripleW View Post
Cool Scott!
Was the brake on or do those motors stop quick?
You could parallel the batteries so the voltage stays equal.
I'm actually not sure. The magnets do have a lot of bite. I was thinking about paralleling the batteries for that reason, and the possibility of it being easier on the batteries. Even with the systems being completely separate there did not seem to be much variation in RPM, both optically and harmonically. The sound was truly unique.

I didn't explain much in the last post. The differential in current between the two motors was right around 1 amp, definitely not enough to concern me. When the plane is closer to completion I plan on getting thrust numbers with each prop spinning alone and then both together to see what is going on.

This weekend hopefully I will have time to start the stabs. I marked the location of the CG on the fuselage and the motor and props are so heavy that I should have absolutely no problem getting the CG where it needs to be.
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Old Jan 12, 2012, 08:07 AM
http://roys-rc-tv.webs.com/
Basingstoke Roy's Avatar
United Kingdom, England, Basingstoke
Joined Oct 2005
455 Posts
Unless your out to get every last usable Watt out of your set-up, I don't think it matters that much if they are bit out. The important thing is have you enough power / thrust to fly the model the way you want. looking at the video I'd say yes!!

As for the battery pack I always connected mine getter, not only dose it make life easer for the pack, It also helps with keeping both motor together, not having one cut long before the other. Not that I expect you would run the pack down that far.

One big pack driving both motors is the "KISS" approach to my way of thinking. Less to go wrong, with charging & operating.
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