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Old Jan 05, 2013, 11:05 PM
Just flitting about!!
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Jim,
that is good work but still concerns me how it adds up.

I've done this work myself for several planes, also did it for the 70" extra and found that the sum of the parts seems to always combine to a higher AUW once the airplane is assembled ready to fly.

For instance, glue for hinges, control arms etc?

Screws for mounting the five servos?

Plugs for the esc and battery connections?

Also, I don't see any of the connector bolts that come with the 70" kit on that spreadsheet.

Anyway, mine on 8s 4000 comes in at 10.33lbs and with a cc100A esc and no sfg's, wheel pants or spinner I should be able to get to 10lb neat.

I'l see.
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Old Jan 05, 2013, 11:06 PM
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Thx
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Old Jan 06, 2013, 10:23 AM
Not as Good as The Kid
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Quote:
Originally Posted by bigroger View Post
Jim,
that is good work but still concerns me how it adds up.

I've done this work myself for several planes, also did it for the 70" extra and found that the sum of the parts seems to always combine to a higher AUW once the airplane is assembled ready to fly.

For instance, glue for hinges, control arms etc?

Screws for mounting the five servos?

Plugs for the esc and battery connections?

Also, I don't see any of the connector bolts that come with the 70" kit on that spreadsheet.

Anyway, mine on 8s 4000 comes in at 10.33lbs and with a cc100A esc and no sfg's, wheel pants or spinner I should be able to get to 10lb neat.

I'l see.
Which cc 100A are you using? I think the Ice2 HV needed for 8S go from 80 to 120.

Her is what I did to get my weight 'projections', which is only the paper weight, of course.

My castle HV120, with everything soldered and ready to go, weighs 177g, which is 34g more than the published "weight with wires".

I included the 111g that is the sum of my Rx, my switch, and my Rx battery.

I also included the 398g that makes up the weight of the servos, servo screws, extensions, and SWB arms with their hardware.

I also included the 86g from the spinner and Xoar prop.

I also added the 33.4g that I seems to have to add to the motor weight. Maybe my soldering is so consistent that both my ESC and motor increase by the same weight, but this is the typical scenario with published weight and reality when solder and bullets need to be attached.

I know the 70 needs a few inches of standoffs and I did not add any of these, and I agree that adhesives are not considered.

If you can let me know the weight of the ESC, I think I can reverse engineer the weight because Ken's motor weights are accurate, but I'll add my 34g anyway. I think that should do it unless you have something else in there, or something less, than what I mentioned.

Thanks, Roger.
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Old Jan 06, 2013, 10:45 AM
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The regular ice 100 handles 8s.
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Old Jan 06, 2013, 11:25 AM
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Didn't know that. Thanks. I think 87-90 Amps are possible with the 8S on a 282Kv and 20x10 prop, and maybe more. Since I like to have the 20% headroom, I may have to add the 21g of insurance.

Do you know if the regular Ice has the logger?
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Old Jan 06, 2013, 12:08 PM
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All ice controllers have the logger. Guys were reporting higher numbers with the 120hv over the regular 100 on the same motor prop combo.
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Old Jan 06, 2013, 01:32 PM
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Good info... I own four CC ESCs and they are all Ice2 HV. I may have to get another 120 since the 100 would limit me to 8S on this plane and I still may go with a 10 or 12 cell setup if I'm disappointed, or if I have a problem with heat when it warms up. I'd hate to have to buy another motor and ESC if that's the case.

I guess the only thing left to do is try to find out if the assembled empty weight is 2334g or 2538g. 7.22 oz seems like a lot of glue and motor mount weight, plus some club members get upset when I fly without pants. There's enough jealousy to go around about my flying prowess.
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Old Jan 06, 2013, 02:46 PM
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I just took a few minutes to review Chris J's data on the first page of the 70 thread. I used his 8S setup with the 2x 4S Flightmax batteries, the Ice 100, the BEC, TP Rx battery, and servos, to reverse engineer the empty weight from his AUW that is virtually the same as Roger's reported weight. I came up with 2368, which is 35g more than Matt's individual component weight, less than my original estimate.

If I use this 2368g weight, and add my components, I come up with and AUW of 4503 or 9.95 lbs with the Ice 100 and 10.00 lbs with the HV120. This gives me about 68g leeway on the setup before the Reynolds number moves out of my preferred range. I doubt I would ever notice this slight increase either way. I also think I was conservative on the power estimate so this should all be good.

I don't think there is any reason to further thread the needle unless I'm leaving out something that will change the weight by more than 5 oz. If I run into problems, I rewind the motor, add the extra 200g in battery weight, drop 22g in ESC weight, add 400W to the power, and go with the 12S setup.
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Old Jan 06, 2013, 05:39 PM
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With a 8s setup you buying new batteries? If so, 6s 2650 are the same weight as 4s 4000
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Old Jan 06, 2013, 06:32 PM
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Yes I will, and I was thinking about two options.... I would really like to go with the 2x Sky 4S 4400 40C pack which is 856g and the 2x Glacier 4S 4000 30C is 824g. The 1 oz difference is about 36 second of flight time with the higher C rating, so I may take the flight time. Not sure yet and I may wait to see where it comes in.

I hear ya about the 12S option.
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Old Jan 06, 2013, 09:58 PM
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Jim,
Chris's set up was on the original electric version of the 70" that is discontinued.

The wood motor box for electric I believe works out lighter then 3"+ standoffs you need to convert the current gas setup of the 70" extra that is available.

I think the only option for me is to go across to the 8s compatible cc ice 100A esc, remove spinner and wheel pants or change over to a Hacker A60-6xs and run 6s setup.

Seems to run pretty good for young Joe Smith on the 3dhs 72" extra he video'd recently and he ran an 21x10 wood prop.
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Old Jan 06, 2013, 10:38 PM
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Originally Posted by bigroger View Post
Jim,
Chris's set up was on the original electric version of the 70" that is discontinued.

The wood motor box for electric I believe works out lighter then 3"+ standoffs you need to convert the current gas setup of the 70" extra that is available.

I think the only option for me is to go across to the 8s compatible cc ice 100A esc, remove spinner and wheel pants or change over to a Hacker A60-6xs and run 6s setup.

Seems to run pretty good for young Joe Smith on the 3dhs 72" extra he video'd recently and he ran an 21x10 wood prop.
Roger, I quoted this before but it's something to consider
Quote:
Originally Posted by joesmith285 View Post
The A60 requires a 21" prop to make good power. This works great on the 74, but I would be afraid that the torque effects wouldn't play well with the 71.
Post found here:
http://www.rcgroups.com/forums/showp...ostcount=26926

I like big props but not to big... Biggest I would go on my 71 is 20".
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Old Jan 06, 2013, 10:53 PM
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I like 27 to 29 percent of the wingspan. 21 on the 74 is fine but I'd not want to push it on a 70.

I was not aware of the e-version and gas version on these planes too. A club buddy has the 72 Extra 330SC on the A60 with the 20x10 on 10S. He also has the 70 EXP, but with a DLE30. I may have to spend a day with Carl to make this decision now. I think he has the 71 Slick too. The 6S is going to be just too hot with the 20 prop... it could go as high as 110A. I'm not a fan of hot, or short flight times.
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Old Jan 06, 2013, 11:08 PM
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With 20% overhead that's 132amps. I know Ken recommends a 120amp or better ESC on the 4330 on 6s. The convenience of 6s is nice but I don't prefer it on planes this size. We need good quality affordable 8,10, and 12s packs already... Maybe in a few years we may see more.
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Old Jan 06, 2013, 11:31 PM
Just flitting about!!
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In my opinion, and I'm running the Dm5320-300 on good 30C gens ace 4s4000 packs that are still measuring IR numbers of 1-2mOhm per cell.

I have tried all sorts of prop sizes, 19x8, 19x10, 20x8 and 20x10 in Xoar and also an Mej 20x8e prop but I still come back to the Xoar 19x10 on this setup.

I found it has plenty of disc size for stable hovers and such and the punch out and flight speed is great. really accelerates the 70" very well and doesn't effect the temperature at all.

I found I actually got longer flight times out of the 19x10 than I did out of either the 19x8 or the 20x8 props on this motor/ cell count combo.

Jim,
there isn't an electric version of this plane anymore. EF phased it out after they had issues with fire walls cracking under stress I believe.
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